Russian: correct the plural of degrees of freedom and make two notes match English

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

.coderabbit.yaml

@@ -0,0 +1,20 @@
+# yaml-language-server: $schema=https://coderabbit.ai/integrations/schema.v2.json
+reviews:
+  auto_review:
+    # Dependabot bumps are checked by CI; skip CodeRabbit reviews on them.
+    ignore_usernames:
+      - "dependabot[bot]"
+  path_instructions:
+    - path: "**"
+      instructions: |
+        Project rule: don't change anyone's existing defaults unless the change is purely additive and belongs in the application.
+        Flag any change to something a user already relies on: a default setting or preference value, what a command or tool does when used the usual way, the UI's default layout or behaviour, a keyboard or mouse shortcut, or the result an existing saved design rebuilds to.
+        Don't flag purely additive changes: a new command, a new setting whose default keeps today's behaviour, or a new option that appears only when someone chooses it. Don't flag bug fixes that only turn a crash or an error into the result the feature always promised.
+        When you flag one, start the comment with "Changes a default:", say what a user sees before and after, whether a setting keeps the old behaviour, and whether the PR description's `Changes a default:` line says so.
+  pre_merge_checks:
+    custom_checks:
+      - name: "Existing defaults unchanged"
+        mode: "warning"
+        instructions: |
+          Pass if the pull request changes no default a user already relies on (default setting or preference values, what a command or tool does when used the usual way, the UI's default layout or behaviour, shortcuts, or the result an existing saved design rebuilds to), or if its changes are purely additive.
+          Fail otherwise, naming each changed default and what a user sees before and after. Also fail if the description says `Changes a default: no` while the code changes one.

ATTRIBUTION.md

@@ -784,6 +784,8 @@ Original SolidCraft drawings, Open for owner review; no runtime assignments.
 | `assets/locales/pending/sketch-offset-instances.json` | SolidCraft contributors | Original offset instance-count label and translations | MIT OR Apache-2.0 |
 | assets/icons/ui/design/svg/flat/settings_profile.svg | SolidCraft contributors | single-colour application/navigation icon master (64 grid), original analytic head and shoulder geometry for settings profiles | MIT OR Apache-2.0 |
 | tests/kernel-cases/import/4561-convert-box-mesh-with-a-zero-area-triangle/box-degenerate.stl | SolidCraft contributors | synthetic ASCII STL written by hand: a box with one zero-area triangle, for the kernel regression case of tangency-labs/solidcraft#4561 | MIT OR Apache-2.0 |
+| assets/locales/pending/theme-blur-ui.json | SolidCraft contributors | Original blur controls, notices and translations | MIT OR Apache-2.0 |
+| crates/ui-egui/tests/fixtures/theme-blur.json | SolidCraft contributors | Original theme for blur option scenarios and manager review | MIT OR Apache-2.0 |
 
 ## Code adapted from sibling projects
 

Cargo.lock

@@ -4102,6 +4102,7 @@ dependencies = [
  "ureq",
  "windows-sys 0.61.2",
  "winit",
+ "winreg",
  "x11rb",
  "zbus 5.19.0",
 ]

apps/solidcraft-web/src/main.rs

@@ -171,6 +171,7 @@ mod web {
 
     use solidcraft_engine::Session;
     use solidcraft_engine::io::vfs;
+    use solidcraft_ui_egui::ui_kit::BackingTooltipExt as _;
     use solidcraft_ui_egui::{Services, SolveApp, ui_kit};
     use wasm_bindgen::JsCast as _;
 
@@ -500,7 +501,7 @@ mod web {
                             files::pick_from_disk(&self.files, Intent::Open);
                         }
                         if ui_kit::button(ui, "Insert from computer…", ui_kit::Button::Normal)
-                            .on_hover_text(solidcraft_ui_egui::i18n::tr("web.files.insert_drawings_hint"))
+                            .backing_on_hover_text(solidcraft_ui_egui::i18n::tr("web.files.insert_drawings_hint"))
                             .clicked()
                         {
                             files::pick_from_disk(&self.files, Intent::Insert);
@@ -554,7 +555,7 @@ mod web {
                                         let design = solidcraft_engine::io::is_design_path(&e.name);
                                         if !design
                                             && ui_kit::button(ui, "Insert", ui_kit::Button::Small)
-                                                .on_hover_text(solidcraft_ui_egui::i18n::tr("web.files.insert_stored_drawings_hint"))
+                                                .backing_on_hover_text(solidcraft_ui_egui::i18n::tr("web.files.insert_stored_drawings_hint"))
                                                 .clicked()
                                         {
                                             act = Some(("insert", e.name.clone()));
@@ -564,7 +565,7 @@ mod web {
                                             self.rename_focus = true;
                                         }
                                         if ui_kit::button(ui, "Save to computer…", ui_kit::Button::Small)
-                                            .on_hover_text("A copy in a file you choose; the stored design stays here")
+                                            .backing_on_hover_text("A copy in a file you choose; the stored design stays here")
                                             .clicked()
                                         {
                                             act = Some(("save_copy", e.name.clone()));

apps/solidcraft/Cargo.toml

@@ -81,6 +81,7 @@ windows-sys = { version = "0.61", features = [
     "Win32_UI_HiDpi",
     "Win32_UI_WindowsAndMessaging",
 ] }
+winreg = "0.56"
 
 [target.'cfg(target_os = "macos")'.dependencies]
 muda = { version = "0.21.2", default-features = false }
@@ -92,7 +93,7 @@ hidapi = { version = "2.6.7", default-features = false, features = ["macos-share
 # Files opened from Finder and the Dock (src/open_documents.rs), and the fullscreen title-bar
 # inset (src/main.rs); all already come with eframe and rfd.
 objc2 = "0.6"
-objc2-app-kit = { version = "0.3", default-features = false, features = ["std", "NSApplication", "NSResponder", "NSWindow"] }
+objc2-app-kit = { version = "0.3", default-features = false, features = ["std", "NSAccessibility", "NSApplication", "NSResponder", "NSWindow", "NSWorkspace"] }
 objc2-foundation = { version = "0.3", default-features = false, features = ["std", "block2", "NSArray", "NSNotification", "NSOperation", "NSProcessInfo", "NSString", "NSURL"] }
 block2 = "0.6"
 # Native crash capture (src/native_crash_macos.rs): the signal handler, the faulting module

apps/solidcraft/src/desktop_transparency.rs

@@ -0,0 +1,63 @@
+//! Cached accessibility signal, observed only while a theme offers blur. No UI-thread IO.
+use std::sync::{
+    Arc,
+    atomic::{AtomicBool, AtomicU8, Ordering},
+};
+
+#[derive(Default)]
+struct Reading {
+    needed: AtomicBool,
+    started: AtomicBool,
+    value: AtomicU8,
+}
+
+pub fn cached(ctx: &egui::Context) -> Box<dyn Fn(bool) -> Option<bool>> {
+    let state = Arc::new(Reading::default());
+    let ctx = ctx.clone();
+    Box::new(move |needed| {
+        state.needed.store(needed, Ordering::Relaxed);
+        if needed && !state.started.swap(true, Ordering::Relaxed) {
+            let weak = Arc::downgrade(&state);
+            let ctx = ctx.clone();
+            if let Err(error) = std::thread::Builder::new().name("desktop-transparency".into()).spawn(move || {
+                while let Some(state) = weak.upgrade() {
+                    if state.needed.load(Ordering::Relaxed) {
+                        let code = match read() {
+                            Some(true) => 1,
+                            Some(false) => 2,
+                            None => 0,
+                        };
+                        if state.value.swap(code, Ordering::Relaxed) != code {
+                            ctx.request_repaint();
+                        }
+                    }
+                    drop(state);
+                    std::thread::sleep(std::time::Duration::from_secs(5));
+                }
+            }) {
+                log::warn!("desktop transparency: could not observe accessibility setting: {error}");
+            }
+        }
+        match state.value.load(Ordering::Relaxed) {
+            1 => Some(true),
+            2 => Some(false),
+            _ => None,
+        }
+    })
+}
+
+#[cfg(target_os = "windows")]
+fn read() -> Option<bool> {
+    let key =
+        winreg::RegKey::predef(winreg::enums::HKEY_CURRENT_USER).open_subkey(r"Software\Microsoft\Windows\CurrentVersion\Themes\Personalize").ok()?;
+    match key.get_value::<u32, _>("EnableTransparency").ok()? {
+        0 => Some(true),
+        1 => Some(false),
+        _ => None,
+    }
+}
+
+#[cfg(target_os = "macos")]
+fn read() -> Option<bool> {
+    objc2::rc::autoreleasepool(|_| Some(objc2_app_kit::NSWorkspace::sharedWorkspace().accessibilityDisplayShouldReduceTransparency()))
+}

apps/solidcraft/src/main.rs

@@ -24,6 +24,8 @@ mod come_forward;
 mod control_server;
 #[cfg(target_os = "linux")]
 mod desktop_theme;
+#[cfg(any(target_os = "windows", target_os = "macos"))]
+mod desktop_transparency;
 mod device_lost;
 #[cfg(target_os = "windows")]
 mod native_crash;
@@ -539,6 +541,10 @@ fn services(cc: &eframe::CreationContext<'_>, folder: &DialogFolder) -> Services
         desktop_dark: Some(desktop_theme::start(&cc.egui_ctx)),
         #[cfg(not(target_os = "linux"))]
         desktop_dark: None,
+        #[cfg(any(target_os = "windows", target_os = "macos"))]
+        reduce_transparency: Some(desktop_transparency::cached(&cc.egui_ctx)),
+        #[cfg(not(any(target_os = "windows", target_os = "macos")))]
+        reduce_transparency: None,
         http_get: Some(std::sync::Arc::new(http_get)),
         http_download: Some(std::sync::Arc::new(http_download)),
         // Already an installed app: only the browser build offers to install.

assets/locales/ar.json

@@ -744,22 +744,22 @@
   "ai.prefs.availability": "التوفر",
   "ai.prefs.background_commands": "تشغيل الأوامر البطيئة في الخلفية",
   "ai.prefs.connect_apps": "إضافة SolidCraft إلى تطبيقات الذكاء الاصطناعي",
-  "ai.prefs.connect_apps_note": "إيقافه يزيل الإدخالات مجدداً.\n\nعند بدء تشغيل SolidCraft، يُضاف كخادم MCP إلى تطبيقات الذكاء الاصطناعي الموجودة على هذا الحاسوب (OpenCode وClaude Desktop وClaude Code وCursor وCodex وGemini CLI وCopilot CLI وWindsurf وZed وVS Code)، ليتمكن الوكيل من استخدامه دون أي إعداد. لا يُضاف إلا مُدخل solidcraft أو يُحدَّث مساره؛ ويُترك المُدخل الذي غيّرته كما هو، ويُنسخ الملف احتياطيًا أولًا. عند الإيقاف تُزال المُدخلات التي أضافها. الأمر «المساعدة > ربط مساعدي الذكاء الاصطناعي…» يفعل ذلك يدويًا.",
+  "ai.prefs.connect_apps_note": "إيقافه يزيل الإدخالات مجددًا.\n\nعند بدء تشغيل SolidCraft، يُضاف كخادم MCP إلى تطبيقات الذكاء الاصطناعي الموجودة على هذا الحاسوب (OpenCode وClaude Desktop وClaude Code وCursor وCodex وGemini CLI وCopilot CLI وWindsurf وZed وVS Code)، ليتمكن الوكيل من استخدامه دون أي إعداد. لا يُضاف إلا مُدخل solidcraft أو يُحدَّث مساره؛ ويُترك المُدخل الذي غيّرته كما هو، ويُنسخ الملف احتياطيًا أولًا. عند الإيقاف تُزال المُدخلات التي أضافها. الأمر «المساعدة > ربط مساعدي الذكاء الاصطناعي…» يفعل ذلك يدويًا.",
   "ai.prefs.connect_at_start": "توصيل آخر وكيل عند البدء",
   "ai.prefs.connect_at_start_note": "يبدأ في الخلفية الوكيل الذي اتصلت به آخر مرة (أو الوكيل الافتراضي) في كل مرة يبدأ فيها SolidCraft، ليكون جاهزًا للمحادثة. لا يحدث ذلك عند بدء SolidCraft مع --control. إذا تعذّر الاتصال، يعرض المساعد «فشل الاتصال» وزر «إعادة المحاولة».",
-  "ai.prefs.follow_camera": "اتباع الكاميرا",
+  "ai.prefs.follow_camera": "تتبّع الكاميرا",
   "ai.prefs.follow_camera_off": "تتبّع الكاميرا التلقائي متوقف.",
   "ai.prefs.follow_camera_on": "تتجه الكاميرا نحو الرسومات التي ينشئها الوكيل.",
   "ai.prefs.intro": "وكلاء الذكاء الاصطناعي في SolidCraft.",
-  "ai.prefs.make_default": "تعيين كافتراضي",
+  "ai.prefs.make_default": "تعيين افتراضيًا",
   "ai.prefs.no_agents": "لا يوجد وكلاء بعد. أضف وكيلًا أو حدّث القائمة للعثور على الوكلاء المثبّتين.",
   "ai.prefs.no_saved_approvals": "لا توجد موافقات محفوظة.",
   "ai.prefs.open_at_start": "فتح المحادثة عند البدء",
   "ai.prefs.open_at_start_note": "يعرض لوحة المساعد (أو نافذتها المستقلة) في كل مرة يبدأ فيها SolidCraft. لا يحدث ذلك عند بدء SolidCraft مع --control.",
   "ai.prefs.override_all_warning": "قد يحفظ هذا الوكيل التصميم أو يكتب فوقه أو يصدّره أو يستبدله دون أن يسأل.",
-  "ai.prefs.permission_all": "فعل كل شيء",
-  "ai.prefs.permission_all_summary": "لا يسأل أبداً",
-  "ai.prefs.permission_ask": "السؤال أولاً",
+  "ai.prefs.permission_all": "تنفيذ كل شيء",
+  "ai.prefs.permission_all_summary": "لا يسأل أبدًا",
+  "ai.prefs.permission_ask": "السؤال أولًا",
   "ai.prefs.permission_ask_summary": "يسأل عن كل تغيير",
   "ai.prefs.permission_edits": "إجراء تعديلات",
   "ai.prefs.permission_edits_summary": "يعدّل بحرية ويسأل عن الباقي",
@@ -1918,7 +1918,7 @@
   "joint.limit_loop": "{side} {value}: لا يمكن لحلقة مغلقة أن تنغلق بعده",
   "joint.limit_range": "{side}: لا تلامس ضمن {range}، تُرك كما كان",
   "joint.limit_turn": "{side} {value}: لا تلامس ضمن دورة واحدة",
-  "joint.limits_overlapping": "متداخلة بالفعل هنا: {pairs}. لا توقف البحث إلا إذا تداخلت أعمق.",
+  "joint.limits_overlapping": "متداخلة بالفعل هنا: {pairs}. لا توقف البحث إلا إذا ازداد تداخلها.",
   "joint.one_body": "كلا الاختيارين على {body}. اختر الثاني على قطعة أخرى.",
   "joint.one_component": "هذه القطع أجسام لمكوّن واحد: {bodies}. المفصل يحرّك مكوّنًا مقابل آخر، لذا تحتاج كل قطعة إلى مكوّن خاص بها.",
   "joint.rigid_group_one_component": "هذه الأجسام وعددها {count} كلها في مكوّن واحد (أو في التصميم نفسه): استخدم {command} أولًا.",
@@ -1933,7 +1933,7 @@
   "joint_move.fine": "الخطوة بعيدًا عن المحور",
   "joint_move.fixed": "لا يملك هذا الجزء محور مفصل قابلًا للحركة.",
   "joint_move.help": "تحريك — اسحب سهمًا أو قوسًا. يلغى السحب الحالي بمفتاح Esc.",
-  "joint_move.legacy_hint": "إيقاف: لوحة التحريك السابقة.",
+  "joint_move.legacy_hint": "عند الإيقاف: لوحة التحريك السابقة.",
   "joint_move.precision": "اسحب خارج الدليل المتقطع للخطوة الدقيقة.",
   "joint_move.rotation": "الدوران من نقطة البداية",
   "joint_move.select": "اختر وجهًا أو جزءًا واحدًا من التجميع، ثم اختر تحريك.",
@@ -2240,7 +2240,7 @@
   "prefs.anti_aliasing_amd_dx12": "يستخدم تنعيم الحواف 1× لأن فحص بدء التشغيل لم يرسم شيئًا مع أخذ العينات المتعددة ونجح عند 1×. يمكنك اختيار إعداد آخر أعلاه؛ أعد التشغيل لتطبيقه إن نجح الفحص.",
   "prefs.anti_aliasing_note": "ينعّم الحواف المسننة.",
   "prefs.appearance.colour_vision_help": "يغيّر الألوان ذات الدلالة: حالات الرسم والمحاور والثنيات والتحليلات والأيقونات.",
-  "prefs.appearance.desktop_only": "لسطح المكتب فقط",
+  "prefs.appearance.desktop_only": "لتطبيق سطح المكتب فقط",
   "prefs.appearance.follow_help": "يعيد التحميل عندما تعيد أداة أخرى كتابة الملف.",
   "prefs.appearance.interface_scale": "مقياس الواجهة",
   "prefs.appearance.next_themes": "السمات التالية",
@@ -2250,11 +2250,11 @@
   "prefs.appearance.theme_count": "{count} سمات",
   "prefs.appearance.theme_own": "ألوان السمة",
   "prefs.appearance.viewport_colours": "ألوان العرض ثلاثي الأبعاد",
-  "prefs.appearance.viewport_logo": "منفذ العرض والشعار",
+  "prefs.appearance.viewport_logo": "منطقة العرض والشعار",
   "prefs.applies_on_restart": "يُطبَّق عند إعادة التشغيل",
   "prefs.assistant": "المساعد",
   "prefs.assistant_connecting": "الاتصال",
-  "prefs.assistant_follow_help": "تحرّك عروض Look At للرسم المنظور مع المؤشر.",
+  "prefs.assistant_follow_help": "النظر إلى الرسومات يحرّك العرض مع المؤشر.",
   "prefs.assistant_limit": "الحد",
   "prefs.assistant_limited": "محدود",
   "prefs.assistant_pointer_speed": "سرعة المؤشر",
@@ -2262,13 +2262,21 @@
   "prefs.assistant_seconds_aria": "الثواني",
   "prefs.assistant_use_care": "استخدم بحذر",
   "prefs.auto_operation": "اختيار العملية تلقائيًا",
-  "prefs.auto_operation_note": "ضم أو جسم جديد أو قطع، حسب ما تلامسه المادة.",
+  "prefs.auto_operation_note": "ضم أو جسم جديد أو قص، حسب ما تلامسه المادة.",
   "prefs.axes": "المحاور",
   "prefs.axis": "المحور",
+  "prefs.blur_cost": "تكلفة العرض النسبية. زيادة الأشرطة تعني عادةً مزيدًا من العمل.",
+  "prefs.blur_device": "غير متاح على جهاز الرسوميات أو مسار العرض هذا",
+  "prefs.blur_guard": "خُفّضت جودة التمويه للحفاظ على استجابة الإطارات. لم يتغير نصف القطر.",
+  "prefs.blur_off": "إيقاف",
+  "prefs.blur_reduce_transparency": "معطّل بسبب إعداد تقليل الشفافية في النظام",
+  "prefs.blur_software": "غير متاح مع الرسوميات البرمجية (gpu-software)",
+  "prefs.blur_source": "غير متاح في عرض مساحة العمل هذا",
+  "prefs.blur_web": "غير متاح في مسار عرض الويب هذا",
   "prefs.bodies_folders": "مجلدات الأجسام",
   "prefs.bodies_folders_always": "دائمًا",
   "prefs.bodies_folders_never": "أبدًا",
-  "prefs.bodies_folders_several": "عدة",
+  "prefs.bodies_folders_several": "عند التعدد",
   "prefs.bottom": "أسفل",
   "prefs.bottom_centre": "أسفل الوسط",
   "prefs.bottom_right": "أسفل اليمين",
@@ -2360,7 +2368,7 @@
   "prefs.graphics_note": "وازن بين السرعة والنعومة. كل خيار يعرض أثره على عيّنة.",
   "prefs.graphics_page.current_view": "العرض الحالي",
   "prefs.graphics_page.fastest": "الأسرع",
-  "prefs.graphics_page.fold_items": "طي العناصر",
+  "prefs.graphics_page.fold_items": "تلخيص العناصر",
   "prefs.graphics_page.in_view": "داخل العرض",
   "prefs.graphics_page.live_details": "تفاصيل مباشرة",
   "prefs.graphics_page.own_mix": "مزيجك الخاص",
@@ -2369,7 +2377,7 @@
   "prefs.graphics_page.restart": "تلزم إعادة التشغيل",
   "prefs.graphics_page.sharpest": "الأكثر وضوحًا",
   "prefs.graphics_page.single_surface_analysis": "تحليل سطح واحد",
-  "prefs.graphics_page.status_chips": "شرائح الحالة",
+  "prefs.graphics_page.status_chips": "شارات الحالة",
   "prefs.graphics_page.subtitle": "وازن بين السرعة والنعومة.",
   "prefs.graphics_page.supersampling": "التنعيم الفائق",
   "prefs.graphics_page.supersampling_adaptive": "فقط أثناء سكون العرض",
@@ -2416,7 +2424,7 @@
   "prefs.layout_page.icons_labels": "الأيقونات + التسميات",
   "prefs.layout_page.ok_cancel": "موافق وإلغاء",
   "prefs.layout_page.on_hover": "عند مرور المؤشر",
-  "prefs.layout_page.open": "فتح",
+  "prefs.layout_page.open": "تُفتح",
   "prefs.layout_page.origin_bodies": "الأصل والأجسام في الأعلى",
   "prefs.layout_page.panels": "اللوحات",
   "prefs.layout_page.pinned_menus": "استبعاد الأوامر المثبتة من القوائم",
@@ -2456,8 +2464,8 @@
   "prefs.navigation.cube_compact": "المكعب",
   "prefs.navigation.device": "الجهاز",
   "prefs.navigation.free": "حر",
-  "prefs.navigation.orbit_style": "نمط الدوران",
-  "prefs.navigation.radial_help": "اضغط مطولاً أو انقر سريعاً بالزر الأيمن لعرض حلقة من الأدوات.",
+  "prefs.navigation.orbit_style": "نمط التدوير",
+  "prefs.navigation.radial_help": "اضغط مطولًا أو انقر سريعًا بالزر الأيمن لعرض حلقة من الأدوات.",
   "prefs.navigation.turntable": "طاولة دوارة",
   "prefs.navigation_note": "كيف تحرك الفأرة ولوحة اللمس والفأرة ثلاثية الأبعاد العرض.",
   "prefs.navigator_fit": "ملاءمة النموذج بعد تغيير العرض من متصفح العرض",
@@ -2475,7 +2483,7 @@
   "prefs.origin_plane_names_note": "الأسماء المعروضة في المستعرض والحوارات والقوائم. {top} هو XY و{front} هو XZ و{right} هو YZ، والمحور Z للأعلى. تحتفظ الأوامر والسكربتات والتصاميم المحفوظة بـ XY وXZ وYZ.",
   "prefs.overall_speed": "السرعة العامة",
   "prefs.parameter_list_rows": "صفوف قائمة المعاملات",
-  "prefs.parameter_list_rows_tip": "الحد الأقصى للمعلمات التي يسردها السهم لأسفل في مربع تعبير فارغ.",
+  "prefs.parameter_list_rows_tip": "الحد الأقصى للمعاملات التي يسردها السهم لأسفل في مربع تعبير فارغ.",
   "prefs.persistent_ribbon_pressed": "تمييز أوامر الشريط النشطة",
   "prefs.persistent_ribbon_pressed_help": "تمييز أوامر الشريط أثناء تفعيل تأثيراتها. أوقف هذا الخيار للاحتفاظ بالمظهر المحايد السابق ومساعدة الأوامر.",
   "prefs.perspective_fov": "مجال الرؤية",
@@ -2544,16 +2552,16 @@
   "prefs.shortcuts_import": "استيراد",
   "prefs.shortcuts_intro": "مفاتيح كل أمر.",
   "prefs.shortcuts_not_assigned": "غير معيّن",
-  "prefs.shortcuts_press": "اضغط مفتاحاً...",
+  "prefs.shortcuts_press": "اضغط مفتاحًا...",
   "prefs.single_surface_analysis": "استخدام تحليل سطح واحد",
   "prefs.single_surface_analysis_help": "عند إيقاف هذا الخيار، يمكن إبقاء تظليل السطح وتحليل الاستمرارية مفعّلين معًا. عند تشغيله، يبقى آخر تحليل تم بدؤه أو تغييره فقط.",
   "prefs.sketch.align_points": "المحاذاة مع نقاط الرسم الأخرى",
   "prefs.sketch.align_points_note": "تتحاذى الخطوط أثناء الرسم مع النقاط على المحورين معًا.",
   "prefs.sketch.auto_dimensions": "إضافة كل الأبعاد للأشكال الجديدة",
   "prefs.sketch.auto_dimensions_note": "القيم المدخلة وكل بُعد يثبّت الشكل.",
-  "prefs.sketch.auto_locate": "التحديد انطلاقًا من أصل الرسم",
+  "prefs.sketch.auto_locate": "تحديد الموضع من أصل الرسم",
   "prefs.sketch.auto_locate_note": "مع إضافة كل الأبعاد.",
-  "prefs.sketch.center_arc": "قوس المركز يتبع المؤشر",
+  "prefs.sketch.center_arc": "القوس بنقطة مركز يتبع المؤشر",
   "prefs.sketch.click_selects": "النقر يحدد",
   "prefs.sketch.conflict_colour": "لون التعارض",
   "prefs.sketch.drawing": "الرسم",
@@ -2568,7 +2576,7 @@
   "prefs.sketch.prefer_free_points": "تفضيل النقاط القابلة للتحريك عند تداخلها",
   "prefs.sketch.project_options": "السؤال عن خيارات الإسقاط أولًا",
   "prefs.sketch.recent_snap": "الالتقاط عند تقاطع دليلين",
-  "prefs.sketch.select_other_hidden": "اختيار آخر يشمل الهندسة المخفية",
+  "prefs.sketch.select_other_hidden": "تحديد آخر يشمل الهندسة المخفية",
   "prefs.sketch.shortcut_cycles_modes": "الاختصار مجددًا يبدّل الوضع",
   "prefs.sketch.shortcut_cycles_modes_tip": "عند الإيقاف: تبدأ الأداة مجددًا.",
   "prefs.sketch.snapping_guides": "الالتقاط والأدلة",
@@ -2650,6 +2658,10 @@
   "prefs.theme_follow_off": "إيقاف",
   "prefs.theme_follow_stop": "إيقاف الاتباع",
   "prefs.theme_import_hint": "انقر لاختيار ملف سمة، أو أفلت ملفًا هنا، أو اضغط Ctrl+V (Cmd+V على Mac) بعد نسخ سمة",
+  "prefs.theme_notice_dismiss": "إخفاء",
+  "prefs.theme_option_blur": "تمويه خلف اللوحات",
+  "prefs.theme_option_blur_help": "تمويه خلف اللوحات شبه الشفافة، بالبكسل الفعلي. الصفر يوقف التمويه.",
+  "prefs.theme_option_invalid": "القيمة المحفوظة للخيار {option} غير صالحة؛ تُستخدم القيمة الافتراضية للسمة. تبقى القيمة المحفوظة كما هي.",
   "prefs.theme_option_opacity": "العتامة",
   "prefs.theme_option_opacity_help": "اضبط عتامة اللوحات العائمة. يُطبّق حد أدنى للعتامة للحفاظ على وضوح النص فوق ألوان منطقة العرض.",
   "prefs.theme_option_tab_colours": "ألوان علامات التبويب",
@@ -2658,6 +2670,7 @@
   "prefs.theme_option_tab_fade_ms_help": "تتغيّر ألوان اللوحات ومنطقة العرض تدريجيًا عند تبديل علامات التبويب. القيمة صفر تبدّلها فورًا.",
   "prefs.theme_options_badge": "الخيارات",
   "prefs.theme_options_more": "المزيد · {count}",
+  "prefs.theme_options_newer": "تتطلب هذه السمة إصدارًا أحدث من SolidCraft. بعد الترقية، أعد استيراد السمة الأصلية لاستعادة تعريفات خياراتها.",
   "prefs.theme_options_reset": "إعادة تعيين",
   "prefs.theme_options_unavailable": "غير متاح على هذا الجهاز",
   "prefs.theme_paste": "لصق السمة",
@@ -2686,7 +2699,7 @@
   "prefs.validation.each_step": "بعد كل خطوة",
   "prefs.validation.label": "فحص النواة الكامل",
   "prefs.validation.off": "متوقف (تجريبي)",
-  "prefs.validation_note": "بعد كل خطوة: يفحص كل عملية سحب ودمج وتقويس.\nمرة لكل ميزة: يفحص ناتج كل ميزة مرة واحدة.\nمتوقف (تجريبي): لا فحص.",
+  "prefs.validation_note": "بعد كل خطوة: يفحص كل عملية كنس وعملية منطقية وتقويس.\nمرة لكل ميزة: يفحص ناتج كل ميزة مرة واحدة.\nمتوقف (تجريبي): لا فحص.",
   "prefs.value_boxes_in_view": "إظهار القيم بجانب مقابضها",
   "prefs.value_boxes_in_view_tip": "مسافة البثق ونصف قطر التدوير... في مربع داخل العرض.",
   "prefs.view": "سلوك العرض",
@@ -4201,13 +4214,13 @@
   "thread.automatic_size": "حجم تلقائي",
   "thread.chamfer_depth_needed": "مطلوب لهذا الشكل",
   "thread.designation": "التسمية",
-  "thread.drill_range": "مثقاب صانع اللقمة {drill} مم. القطر الأصغر القياسي للسن الداخلي {minor} مم. يُقبل مثقاب من {low} إلى {high} مم.",
+  "thread.drill_range": "مثقاب التسنين الذي يوصي به صانعو ذكور التسنين {drill} مم. القطر الأصغر القياسي للسن الداخلي {minor} مم. يُقبل مثقاب من {low} إلى {high} مم.",
   "thread.drill_range_custom": "المثقاب هو القطر الأكبر ناقص الخطوة، {drill} مم. القطر الأصغر القياسي للسن الداخلي {minor} مم. يُقبل مثقاب من {low} إلى {high} مم.",
-  "thread.drill_range_taper": "مثقاب صانع اللقمة {drill} مم. القطر الأصغر القياسي عند نهاية السن {minor} مم. يُقبل مثقاب من {low} إلى {high} مم.",
+  "thread.drill_range_taper": "مثقاب التسنين الذي يوصي به صانعو ذكور التسنين {drill} مم. القطر الأصغر القياسي عند نهاية السن {minor} مم. يُقبل مثقاب من {low} إلى {high} مم.",
   "thread.end_square": "قائمة",
   "thread.fade_short": "1.25 P (ISO 3508)",
   "thread.fade_standard": "2.5 P (ISO 3508)",
-  "thread.fits_the_face": "يناسب الوجه، مثلاً {example}",
+  "thread.fits_the_face": "يناسب الوجه، مثلًا {example}",
   "thread.form_bspp": "سن أنابيب G (ISO 228-1)",
   "thread.form_bspt": "سن أنابيب مخروطي R، Rc (ISO 7-1)",
   "thread.form_npt": "سن أنابيب مخروطي NPT (ASME B1.20.1)",
@@ -4464,7 +4477,7 @@
   "ui.agent_chat_no_images": "هذا الوكيل لا يقبل الصور",
   "ui.agent_chat_no_picture": "لا توجد صورة في الحافظة",
   "ui.agent_chat_no_tool_call": "لم يستخدم النموذج أدوات SolidCraft، لذا لم يتغيّر التصميم. اختر نموذجًا يدعم استدعاء الأدوات؛ راجع «النماذج المحلية» في دليل محادثة الوكيل.",
-  "ui.agent_chat_node_too_old": "إصدار Node.js ‏{version} قديم جدًا لهذا الوكيل. ثبّت Node.js 20.10 أو أحدث، ثم اضغط على تحديث.",
+  "ui.agent_chat_node_too_old": "إصدار Node.js {version} قديم جدًا لهذا الوكيل. ثبّت Node.js 20.10 أو أحدث، ثم اضغط تحديث.",
   "ui.agent_chat_none_found": "لم يُعثر على وكيل برمجي. ثبّت أحد هذه ثم اضغط تحديث:",
   "ui.agent_chat_none_found_short": "لم يُعثر على وكيل",
   "ui.agent_chat_not_installed": "غير مثبت",
@@ -4505,7 +4518,7 @@
   "ui.agent_chat_send_now_tip": "إيقاف خطوة الوكيل الحالية وإرسال هذه بعدها (Ctrl+Enter)",
   "ui.agent_chat_setup_body": "يتواصل SolidCraft مع وكيل برمجة مثبّت على هذا الحاسوب. اختر واحدًا من التفضيلات › الوكيل.",
   "ui.agent_chat_setup_title": "إعداد مساعد",
-  "ui.agent_chat_side": "إرساء المحادثة",
+  "ui.agent_chat_side": "تثبيت المحادثة",
   "ui.agent_chat_signed_in": "سجّل الدخول",
   "ui.agent_chat_state_auth": "يلزم تسجيل الدخول",
   "ui.agent_chat_state_busy": "جارٍ العمل…",
@@ -4570,10 +4583,10 @@
   "ui.ai_key_note": "يُخزّن في سلسلة مفاتيح النظام، وليس في إعدادات SolidCraft أبدًا. اتركه فارغًا لخادم محلي.",
   "ui.ai_keychain_error": "رفضت سلسلة مفاتيح النظام: {error}",
   "ui.ai_kind": "النوع",
-  "ui.ai_mode_all": "فعل كل شيء",
+  "ui.ai_mode_all": "تنفيذ كل شيء",
   "ui.ai_mode_all_note": "لا شيء يسأل أولًا. تبقى تقارير الأعطال محظورة وتظل حدود المجلدات سارية.",
   "ui.ai_mode_all_warning": "يمكن للوكيل حفظ تصميمك والكتابة فوقه وتصديره واستبداله دون سؤال. استخدم هذا فقط مع وكيل تثق به، وعلى تصاميم حفظتها.",
-  "ui.ai_mode_ask": "السؤال أولاً",
+  "ui.ai_mode_ask": "السؤال أولًا",
   "ui.ai_mode_ask_note": "كل تغيير في التصميم وكل إجراء على الملفات ينتظر سماحك.",
   "ui.ai_mode_edits": "إجراء تعديلات",
   "ui.ai_mode_edits_note": "أوامر النمذجة تعمل دون سؤال؛ أما الحفظ والفتح والتصدير وإجراءات الملفات أو الإجراءات الهدّامة الأخرى فتسأل.",
@@ -4744,21 +4757,21 @@
   "ui.construction.ribbon_label": "خطوط مساعدة",
   "ui.construction.side_hint": "خط إنشائي: انقر الجهة التي يمتد نحوها الخط؛ انقر بزر الفأرة الأيمن للبدء من جديد",
   "ui.context_menu": "القائمة السياقية",
-  "ui.continuity_crease": "تجعّد",
+  "ui.continuity_crease": "ثنية",
   "ui.continuity_curvature": "الانحناء",
   "ui.continuity_curvature_change": "تغيّر الانحناء",
   "ui.continuity_curvature_change_tip": "تغيّر الانحناء (G3): يتغير الانحناء أيضًا بسلاسة عبر خط الالتقاء.",
   "ui.continuity_curvature_tip": "متصل الانحناء (G2): تمر الانعكاسات دون انكسار.",
-  "ui.continuity_g0": "G0 تجعّد",
+  "ui.continuity_g0": "G0 ثنية",
   "ui.continuity_g1": "G1 مماس",
   "ui.continuity_g2": "G2 انحناء",
   "ui.continuity_gap": "فجوة",
   "ui.continuity_position": "الموضع",
-  "ui.continuity_position_tip": "الموضع (G0): تلتقي الأسطح، مع تجعّد عند التقائها.",
+  "ui.continuity_position_tip": "الموضع (G0): تلتقي الأسطح، مع ثنية عند التقائها.",
   "ui.continuity_smooth_curvature_change": "تغيّر انحناء سلس",
   "ui.continuity_smooth_curvature_change_tip": "تغيّر انحناء سلس (G4): حتى طريقة تغيّر الانحناء تستمر بسلاسة عبر خط الالتقاء.",
   "ui.continuity_tangent": "مماس",
-  "ui.continuity_tangent_tip": "مماس (G1): لا تجعّد، لكن الانحناء يقفز عبر خط الالتقاء.",
+  "ui.continuity_tangent_tip": "مماس (G1): لا ثنية، لكن الانحناء يقفز عبر خط الالتقاء.",
   "ui.copy": "نسخ",
   "ui.copy_details": "نسخ التفاصيل",
   "ui.copy_details_tip": "انسخ الرسالة كاملة للبحث عنها أو للإبلاغ عنها.",
@@ -4909,7 +4922,7 @@
   "ui.extract_done": "أصبح المكوّن تصميمًا مستقلًا، مرتبطًا هنا.",
   "ui.extrude": "بثق",
   "ui.extrude_auto_to_object": "البثق إلى هدف مختار",
-  "ui.extrude_auto_to_object_tip": "وجه أو رأس أو مستوى موازٍ يغيّر المدى إلى «إلى كائن».",
+  "ui.extrude_auto_to_object_tip": "وجه أو رأس أو مستوى موازٍ يغيّر الامتداد إلى «إلى كائن».",
   "ui.factor": "المعامل",
   "ui.fade": "تلاشٍ",
   "ui.fade_length": "طول التلاشي",
@@ -4939,9 +4952,13 @@
   "ui.fillet_setback": "مسافة الإرجاع",
   "ui.fillet_setback_hint": "{factor} × نصف القطر",
   "ui.fillet_setback_least": "أكثر من {least}",
-  "ui.fillet_setback_tip": "حيث تبدأ رقعة الزاوية الناعمة: المسافة على طول كل حافة من الزاوية. الافتراضي {factor} ضعف نصف القطر. يجب أن تكون أكبر من أقل مسافة إرجاع، حيث تلتقي الاستدارات بدونها: نصف القطر حيث تكون الأوجه متعامدة.",
+  "ui.fillet_setback_tip": "حيث تبدأ رقعة الزاوية الناعمة: المسافة على طول كل حافة من الزاوية. الافتراضي {factor} ضعف نصف القطر. يجب أن تكون أكبر من أقل مسافة إرجاع، وهي التي تلتقي عندها التقويسات دون إرجاع: نصف القطر حين تكون الأوجه متعامدة.",
   "ui.fillet_smooth_radius": "تغيّر ناعم لنصف القطر",
-  "ui.fillet_type_choices_tip": "نصف قطر ثابت: نصف قطر واحد على طول الحافة.\nطول الوتر: يبقى عرض التقويس نفسه مهما كانت الزاوية بين الوجوه.\nنصف قطر متغيّر: نصف قطر عند كل طرف، ومزيد على طول الحافة إن أضفته.\nمتصل الانحناء: مقطع بلا انكسار في الانعكاسات حيث يلتقي بالوجوه المستوية (G2).\nمنحنى: يتبع نصف القطر على طول الحافة أنصاف أقطار تحكّم تحدّدها.",
+  "ui.fillet_turn": "الالتفاف",
+  "ui.fillet_turn_mitre": "وصلة مائلة",
+  "ui.fillet_turn_swept": "ملتف",
+  "ui.fillet_turn_tip": "حيث يلتف تقويسان حول حافة ركن حادة بينهما، مثل التقويسات على قاعدة نتوء عند حوافه القائمة.\nوصلة مائلة: يمتد التقويسان حتى يلتقيا في وصلة مائلة.\nملتف: يتوقف التقويسان عند حافة الركن ويلتفان حولها، والركن طارة مماسة لكليهما. فقط لتقويسين بنصف قطر واحد حول حافة ركن مستقيمة ومحدبة.",
+  "ui.fillet_type_choices_tip": "نصف قطر ثابت: نصف قطر واحد على طول الحافة.\nطول الوتر: يبقى عرض التقويس نفسه مهما كانت الزاوية بين الوجوه.\nنصف قطر متغيّر: نصف قطر عند كل طرف، ومزيد على طول الحافة إن أضفته.\nمتصل الانحناء: مقطع بلا انكسار في الانعكاسات حيث يلتقي بالوجوه المستوية (G2).\nمنحنى شريحي: يتبع نصف القطر على طول الحافة أنصاف أقطار تحكّم تحدّدها.",
   "ui.fillet_type_curvature": "متصل الانحناء",
   "ui.fillet_type_tip": "المقطع عبر الحافة. متصل الانحناء: مقطع متصل الانحناء (G2) بين وجوه مستوية، فتمر الانعكاسات من الوجوه إلى التقويس دون انكسار.",
   "ui.filter_commands_or_keys": "تصفية الأوامر أو المفاتيح",
@@ -5053,7 +5070,7 @@
   "ui.hidePlanes": "إخفاء المستويات",
   "ui.hideProfile": "إخفاء المقطع",
   "ui.hide_component_history": "إخفاء سجله",
-  "ui.hide_origin_by_default": "إخفاء مجلد الأصل في التصاميم الجديدة",
+  "ui.hide_origin_by_default": "إخفاء مجلد نقطة الأصل في التصاميم الجديدة",
   "ui.hide_origin_note": "تبدأ التصاميم الجديدة ومجلد نقطة الأصل مخفي. يحتفظ كل تصميم بإعداد نقطة الأصل الخاص به بمجرد إظهارها أو إخفائها.",
   "ui.history_back": "الرجوع خطوة",
   "ui.history_below_browser": "أسفل المستعرض",

assets/locales/de.json

@@ -2248,6 +2248,14 @@
   "prefs.auto_operation_note": "Vereinigung, Neuer Körper oder Schnitt, je nachdem, was das Material berührt.",
   "prefs.axes": "Achsen",
   "prefs.axis": "Achse",
+  "prefs.blur_cost": "Relativer Renderaufwand. Mehr Balken bedeuten meist mehr Arbeit.",
+  "prefs.blur_device": "Auf diesem Grafikgerät oder Renderpfad nicht verfügbar",
+  "prefs.blur_guard": "Die Unschärfequalität wurde für flüssigere Bilder verringert. Der Radius bleibt unverändert.",
+  "prefs.blur_off": "Aus",
+  "prefs.blur_reduce_transparency": "Durch die Systemeinstellung zur Transparenzreduzierung deaktiviert",
+  "prefs.blur_software": "Mit Softwaregrafik nicht verfügbar (gpu-software)",
+  "prefs.blur_source": "In dieser Arbeitsbereichsansicht nicht verfügbar",
+  "prefs.blur_web": "Auf diesem Web-Renderpfad nicht verfügbar",
   "prefs.bodies_folders": "Körperordner",
   "prefs.bodies_folders_always": "Immer",
   "prefs.bodies_folders_never": "Nie",
@@ -2628,6 +2636,10 @@
   "prefs.theme_follow_off": "Aus",
   "prefs.theme_follow_stop": "Nicht mehr folgen",
   "prefs.theme_import_hint": "Klicken, um eine Designdatei zu wählen, eine hierher ziehen oder mit kopiertem Design Strg+V (Cmd+V auf dem Mac) drücken",
+  "prefs.theme_notice_dismiss": "Ausblenden",
+  "prefs.theme_option_blur": "Unschärfe hinter Panels",
+  "prefs.theme_option_blur_help": "Unschärfe hinter durchscheinenden Panels in physischen Pixeln. Null bedeutet aus.",
+  "prefs.theme_option_invalid": "Der gespeicherte Wert für {option} ist ungültig; der Designstandard wird verwendet. Der gespeicherte Wert bleibt erhalten.",
   "prefs.theme_option_opacity": "Deckkraft",
   "prefs.theme_option_opacity_help": "Deckkraft schwebender Bedienfelder anpassen. Eine Mindestdeckkraft schützt die Lesbarkeit über den Ansichtsfarben.",
   "prefs.theme_option_tab_colours": "Tabfarben",
@@ -2636,6 +2648,7 @@
   "prefs.theme_option_tab_fade_ms_help": "Panel- und Ansichtsfarben beim Tabwechsel überblenden. Null wechselt sofort.",
   "prefs.theme_options_badge": "Optionen",
   "prefs.theme_options_more": "Mehr · {count}",
+  "prefs.theme_options_newer": "Dieses Design benötigt eine neuere Version von SolidCraft. Nach dem Upgrade das Originaldesign erneut importieren, um seine Optionsdefinitionen wiederherzustellen.",
   "prefs.theme_options_reset": "Zurücksetzen",
   "prefs.theme_options_unavailable": "Auf diesem Gerät nicht verfügbar",
   "prefs.theme_paste": "Design einfügen",
@@ -4914,6 +4927,10 @@
   "ui.fillet_setback_least": "Mehr als {least}",
   "ui.fillet_setback_tip": "Wo das glatte Eckflächenstück beginnt: wie weit von der Ecke entlang jeder Kante. Standard ist {factor} × der Radius. Er muss größer sein als der kleinste Rücksprung, wo sich die Rundungen ohne ihn treffen: der Radius, wo die Flächen rechtwinklig zueinander stehen.",
   "ui.fillet_smooth_radius": "Radius glatt ändern",
+  "ui.fillet_turn": "Wendungen",
+  "ui.fillet_turn_mitre": "Gehrung",
+  "ui.fillet_turn_swept": "Geschwenkt",
+  "ui.fillet_turn_tip": "Wo zwei Rundungen um eine scharfe Eckkante zwischen ihnen herumlaufen, etwa die Rundungen am Fuß eines Zapfens an seinen senkrechten Kanten.\nGehrung: Die Rundungen laufen weiter, bis sie sich in einer Gehrung treffen.\nGeschwenkt: Die Rundungen enden an der Eckkante und schwenken um sie herum; die Ecke ist ein Torus, tangential zu beiden. Nur für Rundungen mit einem Radius um eine gerade, konvexe Eckkante.",
   "ui.fillet_type_choices_tip": "Konstanter Radius: ein Radius entlang der ganzen Kante.\nSehnenlänge: die Breite der Rundung bleibt gleich, in welchem Winkel die Flächen auch aufeinandertreffen.\nVariabler Radius: ein Radius an jedem Ende und weitere entlang der Kante, wenn Sie sie hinzufügen.\nKrümmungsstetig: ein Querschnitt ohne Knick in den Spiegelungen, wo er auf ebene Flächen trifft (G2).\nSpline: der Radius entlang der Kante folgt Steuerradien, die Sie festlegen.",
   "ui.fillet_type_curvature": "Krümmungsstetig",
   "ui.fillet_type_tip": "Der Querschnitt über die Kante. Krümmungsstetig: ein krümmungsstetiger Querschnitt (G2) zwischen ebenen Flächen, sodass Spiegelungen ohne Knick von den Flächen in die Rundung laufen.",

assets/locales/en.json

@@ -1600,7 +1600,7 @@
   "help.parts.resize": "Changes the size or length of an inserted standard part and rebuilds it; its joints keep it seated. Use it when a screw turns out too long or a hole needs another size.",
   "help.plastic.assign_rule": "Assigns a plastic rule to bodies, so their plastic features take its draft and clearance as defaults. Use it to set up a moulded part once for all its features.",
   "help.plastic.boss": "Adds a screw boss on a face: a post with an optional hole, draft, root fillet and supporting ribs. Use it for screw points in moulded or printed housings.",
-  "help.plastic.lip": "Adds a lip or a matching groove along the rim of a shelled body. Use it so that two housing halves locate on each other and close tightly.",
+  "help.plastic.lip": "Adds a lip or a matching groove along the rim of a shelled body (Shell a face open first, then pick the rim around that opening). Use it so that two housing halves locate on each other and close tightly.",
   "help.plastic.manage_rules": "Creates and edits plastic rules: material, wall thickness, radii, clearance and draft. Use them to keep the features of a moulded part consistent.",
   "help.plastic.rest": "Adds a rest on a face: a round or rectangular pad, solid or hollow, with draft. Use it as a support or standoff in a moulded housing.",
   "help.plastic.snap_fit": "Adds a snap-fit hook on a face, with its length, thickness and catch. Use it to clip parts together without screws.",
@@ -2265,6 +2265,14 @@
   "prefs.auto_operation_note": "Join, New Body or Cut, from what the material touches.",
   "prefs.axes": "Axes",
   "prefs.axis": "Axis",
+  "prefs.blur_cost": "Relative rendering cost. More bars usually mean more work.",
+  "prefs.blur_device": "Unavailable on this graphics device or rendering path",
+  "prefs.blur_guard": "Blur quality was reduced to keep frames responsive. The radius is unchanged.",
+  "prefs.blur_off": "Off",
+  "prefs.blur_reduce_transparency": "Disabled by the system's Reduce transparency setting",
+  "prefs.blur_software": "Unavailable with software graphics (gpu-software)",
+  "prefs.blur_source": "Unavailable in this workspace view",
+  "prefs.blur_web": "Unavailable on this web rendering path",
   "prefs.bodies_folders": "Bodies folders",
   "prefs.bodies_folders_always": "Always",
   "prefs.bodies_folders_never": "Never",
@@ -2650,6 +2658,10 @@
   "prefs.theme_follow_off": "Off",
   "prefs.theme_follow_stop": "Stop following",
   "prefs.theme_import_hint": "Click to choose a theme file, drop one here, or press Ctrl+V (Cmd+V on a Mac) with a theme copied",
+  "prefs.theme_notice_dismiss": "Dismiss",
+  "prefs.theme_option_blur": "Blur behind panels",
+  "prefs.theme_option_blur_help": "Blur behind translucent panels, in physical pixels. Zero is off.",
+  "prefs.theme_option_invalid": "Saved value for {option} is invalid; using the theme default. The saved value is kept.",
   "prefs.theme_option_opacity": "Opacity",
   "prefs.theme_option_opacity_help": "Adjust floating panel opacity. A readability floor protects text over viewport colors.",
   "prefs.theme_option_tab_colours": "Tab colors",
@@ -2658,6 +2670,7 @@
   "prefs.theme_option_tab_fade_ms_help": "Fade panel and viewport colors when switching tabs. Zero switches instantly.",
   "prefs.theme_options_badge": "Options",
   "prefs.theme_options_more": "More · {count}",
+  "prefs.theme_options_newer": "This theme requires a newer SolidCraft. Upgrade, then reimport the original theme to recover its option definitions.",
   "prefs.theme_options_reset": "Reset",
   "prefs.theme_options_unavailable": "Unavailable on this device",
   "prefs.theme_paste": "Paste theme",
@@ -4941,6 +4954,10 @@
   "ui.fillet_setback_least": "More than {least}",
   "ui.fillet_setback_tip": "Where the smooth corner patch starts: how far along each edge from the corner. The default is {factor} × the radius. It must be more than the least setback, where the rounds meet without one: the radius where the faces are square to each other.",
   "ui.fillet_smooth_radius": "Smooth radius change",
+  "ui.fillet_turn": "Turns",
+  "ui.fillet_turn_mitre": "Mitre",
+  "ui.fillet_turn_swept": "Swept",
+  "ui.fillet_turn_tip": "Where two rounds turn round a sharp corner edge between them, such as the rounds along a boss's base at its upright edges.\nMitre: the rounds run on until they meet in a mitre.\nSwept: the rounds stop at the corner edge and turn round it, the corner a torus tangent to both. Only for rounds of one radius round a straight, convex corner edge.",
   "ui.fillet_type_choices_tip": "Constant radius: one radius all along the edge.\nChord length: the width across the round stays the same, whatever angle the faces meet at.\nVariable radius: a radius at each end, and more along the edge if you add them.\nCurvature continuous: a section without a kink in reflections where it meets flat faces (G2).\nSpline: the radius along the edge follows control radii you set.",
   "ui.fillet_type_curvature": "Curvature continuous",
   "ui.fillet_type_tip": "The section across the edge. Curvature continuous: a curvature-continuous (G2) section between planar faces, so reflections run from the faces into the round without a kink.",

assets/locales/he.json

@@ -2265,6 +2265,14 @@
   "prefs.auto_operation_note": "איחוד, גוף חדש או חיתוך, לפי מה שהחומר נוגע בו.",
   "prefs.axes": "צירים",
   "prefs.axis": "ציר",
+  "prefs.blur_cost": "עלות עיבוד יחסית. יותר פסים מציינים בדרך כלל יותר עבודה.",
+  "prefs.blur_device": "לא זמין בהתקן הגרפי או בנתיב העיבוד הזה",
+  "prefs.blur_guard": "איכות הטשטוש הופחתה כדי לשמור על תגובתיות הפריימים. הרדיוס לא השתנה.",
+  "prefs.blur_off": "כבוי",
+  "prefs.blur_reduce_transparency": "מושבת עקב הגדרת הפחתת השקיפות של המערכת",
+  "prefs.blur_software": "לא זמין עם עיבוד גרפי בתוכנה (gpu-software)",
+  "prefs.blur_source": "לא זמין בתצוגת סביבת העבודה הזו",
+  "prefs.blur_web": "לא זמין בנתיב העיבוד הזה בדפדפן",
   "prefs.bodies_folders": "תיקיות גופים",
   "prefs.bodies_folders_always": "תמיד",
   "prefs.bodies_folders_never": "אף פעם",
@@ -2650,6 +2658,10 @@
   "prefs.theme_follow_off": "כבוי",
   "prefs.theme_follow_stop": "הפסקת המעקב",
   "prefs.theme_import_hint": "לחצו כדי לבחור קובץ ערכת נושא, שחררו קובץ כאן, או הקישו Ctrl+V ‏(Cmd+V ב-Mac) אחרי שהעתקתם ערכת נושא",
+  "prefs.theme_notice_dismiss": "הסתרה",
+  "prefs.theme_option_blur": "טשטוש מאחורי לוחות",
+  "prefs.theme_option_blur_help": "טשטוש מאחורי לוחות שקופים למחצה, בפיקסלים פיזיים. אפס מכבה את הטשטוש.",
+  "prefs.theme_option_invalid": "הערך השמור עבור {option} אינו תקין; נעשה שימוש בברירת המחדל של ערכת הנושא. הערך השמור נשמר ללא שינוי.",
   "prefs.theme_option_opacity": "אטימות",
   "prefs.theme_option_opacity_help": "כוונון אטימות הלוחות הצפים. רמת אטימות מינימלית שומרת על קריאות הטקסט על רקע צבעי חלון התצוגה.",
   "prefs.theme_option_tab_colours": "צבעי כרטיסיות",
@@ -2658,6 +2670,7 @@
   "prefs.theme_option_tab_fade_ms_help": "שנה בהדרגה את צבעי הלוח ואזור התצוגה בעת מעבר בין כרטיסיות. ערך אפס מבצע את המעבר מיד.",
   "prefs.theme_options_badge": "אפשרויות",
   "prefs.theme_options_more": "עוד · {count}",
+  "prefs.theme_options_newer": "ערכת נושא זו דורשת גרסה חדשה יותר של SolidCraft. לאחר השדרוג יש לייבא שוב את ערכת הנושא המקורית כדי לשחזר את הגדרות האפשרויות שלה.",
   "prefs.theme_options_reset": "איפוס",
   "prefs.theme_options_unavailable": "לא זמין במכשיר זה",
   "prefs.theme_paste": "הדבקת ערכת נושא",
@@ -4941,6 +4954,10 @@
   "ui.fillet_setback_least": "יותר מ-{least}",
   "ui.fillet_setback_tip": "היכן מתחיל טלאי הפינה החלק: המרחק לאורך כל קצה מהפינה. ברירת המחדל היא פי {factor} מהרדיוס. עליה להיות גדולה מהנסיגה המזערית, שבה העיגולים נפגשים בלעדיה: הרדיוס כשהפאות ניצבות זו לזו.",
   "ui.fillet_smooth_radius": "שינוי רדיוס חלק",
+  "ui.fillet_turn": "פניות",
+  "ui.fillet_turn_mitre": "מיטר",
+  "ui.fillet_turn_swept": "מסובב",
+  "ui.fillet_turn_tip": "היכן ששני עיגולים מסתובבים סביב קצה פינה חד ביניהם, כמו העיגולים בבסיס בליטה ליד הקצוות הזקופים שלה.\nמיטר: העיגולים נמשכים עד שהם נפגשים במיטר.\nמסובב: העיגולים נעצרים בקצה הפינה ומסתובבים סביבו, והפינה היא טורוס המשיק לשניהם. רק לעיגולים ברדיוס אחד סביב קצה פינה ישר וקמור.",
   "ui.fillet_type_choices_tip": "רדיוס קבוע: רדיוס אחד לכל אורך הקצה.\nאורך מיתר: רוחב העיגול נשאר זהה, בכל זווית שבה הפאות נפגשות.\nרדיוס משתנה: רדיוס בכל קצה, ועוד לאורך הקצה אם מוסיפים.\nרציף בעקמומיות: חתך בלי שבר בהשתקפויות היכן שהוא פוגש פאות מישוריות (G2).\nספליין: הרדיוס לאורך הקצה עוקב אחרי רדיוסי בקרה שאתם קובעים.",
   "ui.fillet_type_curvature": "רציף בעקמומיות",
   "ui.fillet_type_tip": "החתך לרוחב הקצה. רציף בעקמומיות: חתך רציף בעקמומיות (G2) בין פאות מישוריות, כך שההשתקפויות עוברות מהפאות אל העיגול בלי שבר.",

assets/locales/ja.json

@@ -2265,6 +2265,14 @@
   "prefs.auto_operation_note": "材料が接触する対象に応じて結合、新規ボディ、切り取りを選びます。",
   "prefs.axes": "軸",
   "prefs.axis": "軸",
+  "prefs.blur_cost": "相対的な描画負荷です。バーが多いほど、通常は処理量が増えます。",
+  "prefs.blur_device": "このグラフィックスデバイスまたは描画経路では利用できません",
+  "prefs.blur_guard": "画面の応答性を保つため、ぼかしの品質を下げました。半径は変更されていません。",
+  "prefs.blur_off": "オフ",
+  "prefs.blur_reduce_transparency": "システムの透明度を下げる設定により無効です",
+  "prefs.blur_software": "ソフトウェア描画では利用できません (gpu-software)",
+  "prefs.blur_source": "このワークスペース表示では利用できません",
+  "prefs.blur_web": "このウェブ描画経路では利用できません",
   "prefs.bodies_folders": "ボディフォルダー",
   "prefs.bodies_folders_always": "常に表示",
   "prefs.bodies_folders_never": "表示しない",
@@ -2650,6 +2658,10 @@
   "prefs.theme_follow_off": "オフ",
   "prefs.theme_follow_stop": "追従を停止",
   "prefs.theme_import_hint": "クリックしてテーマファイルを選ぶか、ここにドロップするか、テーマをコピーした状態で Ctrl+V（Mac では Cmd+V）を押します",
+  "prefs.theme_notice_dismiss": "非表示",
+  "prefs.theme_option_blur": "パネル背面のぼかし",
+  "prefs.theme_option_blur_help": "半透明パネルの背面のぼかしを物理ピクセル単位で指定します。0でオフになります。",
+  "prefs.theme_option_invalid": "{option} の保存値が無効なため、テーマの既定値を使用します。保存値は保持されます。",
   "prefs.theme_option_opacity": "不透明度",
   "prefs.theme_option_opacity_help": "フローティングパネルの不透明度を調整します。ビューポートの色に重なっても文字が読めるように下限が適用されます。",
   "prefs.theme_option_tab_colours": "タブの色",
@@ -2658,6 +2670,7 @@
   "prefs.theme_option_tab_fade_ms_help": "タブの切り替え時にパネルとビューポートの色を徐々に変えます。0で即座に切り替えます。",
   "prefs.theme_options_badge": "オプション",
   "prefs.theme_options_more": "その他 · {count}",
+  "prefs.theme_options_newer": "このテーマには新しいバージョンの SolidCraft が必要です。更新後、元のテーマを再インポートしてオプション定義を復元してください。",
   "prefs.theme_options_reset": "リセット",
   "prefs.theme_options_unavailable": "このデバイスでは利用できません",
   "prefs.theme_paste": "テーマを貼り付け",
@@ -4941,6 +4954,10 @@
   "ui.fillet_setback_least": "{least} より大きく",
   "ui.fillet_setback_tip": "なめらかなコーナーパッチが始まる位置: コーナーから各エッジに沿った距離。既定値は半径の {factor} 倍。最小セットバック (セットバックなしでラウンド同士が交わる位置。面どうしが直角なら半径) より大きくする必要があります。",
   "ui.fillet_smooth_radius": "半径をなめらかに変化",
+  "ui.fillet_turn": "曲がり角",
+  "ui.fillet_turn_mitre": "留め継ぎ",
+  "ui.fillet_turn_swept": "回転",
+  "ui.fillet_turn_tip": "2 つのフィレットが間にある鋭いコーナーエッジを回り込む所（ボスの根元のフィレットが立ち上がりエッジを回る所など）。\n留め継ぎ: フィレットは延びて留め継ぎで出会います。\n回転: フィレットはコーナーエッジで止まり、その周りを回ります。コーナーは両方に接するトーラスです。同じ半径のフィレットが、まっすぐな凸のコーナーエッジを回る場合のみ。",
   "ui.fillet_type_choices_tip": "一定の半径: エッジ全体で一つの半径。\n弦長: 面がどんな角度で交わっても、フィレットの幅が同じ。\n可変半径: 両端の半径と、追加すればエッジ沿いの半径。\n曲率連続: 平面と接する所で映り込みが折れない断面 (G2)。\nスプライン: エッジ沿いの半径が、設定した制御半径に従います。",
   "ui.fillet_type_curvature": "曲率連続",
   "ui.fillet_type_tip": "エッジを横切る断面。曲率連続: 平面の間の曲率連続 (G2) 断面で、映り込みが面からフィレットへ折れずにつながります。",

assets/locales/ko.json

@@ -1657,6 +1657,14 @@
   "prefs.auto_operation_note": "재료가 닿는 대상에 따라 결합, 새 바디 또는 자르기를 선택합니다.",
   "prefs.axes": "축",
   "prefs.axis": "축",
+  "prefs.blur_cost": "상대적인 렌더링 비용입니다. 막대가 많을수록 일반적으로 더 많은 작업이 필요합니다.",
+  "prefs.blur_device": "이 그래픽 장치 또는 렌더링 경로에서는 사용할 수 없습니다",
+  "prefs.blur_guard": "화면의 원활한 응답을 위해 흐림 품질을 낮췄습니다. 반경은 변경되지 않습니다.",
+  "prefs.blur_off": "끄기",
+  "prefs.blur_reduce_transparency": "시스템의 투명도 줄이기 설정에 의해 비활성화됨",
+  "prefs.blur_software": "소프트웨어 그래픽에서는 사용할 수 없습니다 (gpu-software)",
+  "prefs.blur_source": "이 작업 공간 보기에서는 사용할 수 없습니다",
+  "prefs.blur_web": "이 웹 렌더링 경로에서는 사용할 수 없습니다",
   "prefs.bodies_folders": "바디 폴더",
   "prefs.bodies_folders_always": "항상 표시",
   "prefs.bodies_folders_never": "표시 안 함",
@@ -1975,6 +1983,10 @@
   "prefs.theme_follow_note": "다른 도구가 파일을 다시 쓸 때마다 다시 불러옵니다. 테마를 선택하면 따르기를 중지합니다.",
   "prefs.theme_follow_off": "끄기",
   "prefs.theme_follow_stop": "따르기 중지",
+  "prefs.theme_notice_dismiss": "닫기",
+  "prefs.theme_option_blur": "패널 뒤 흐림",
+  "prefs.theme_option_blur_help": "반투명 패널 뒤의 흐림을 물리적 픽셀 단위로 설정합니다. 0이면 꺼집니다.",
+  "prefs.theme_option_invalid": "{option}의 저장된 값이 유효하지 않아 테마 기본값을 사용합니다. 저장된 값은 유지됩니다.",
   "prefs.theme_option_opacity": "불투명도",
   "prefs.theme_option_opacity_help": "플로팅 패널의 불투명도를 조정합니다. 뷰포트 색상 위에서도 텍스트를 읽을 수 있도록 최솟값이 적용됩니다.",
   "prefs.theme_option_tab_colours": "탭 색상",
@@ -1983,6 +1995,7 @@
   "prefs.theme_option_tab_fade_ms_help": "탭을 전환할 때 패널 및 뷰포트 색상을 서서히 변경합니다. 0이면 즉시 전환합니다.",
   "prefs.theme_options_badge": "옵션",
   "prefs.theme_options_more": "더 보기 · {count}",
+  "prefs.theme_options_newer": "이 테마에는 더 최신 버전의 SolidCraft가 필요합니다. 업그레이드 후 원본 테마를 다시 가져와 옵션 정의를 복구하세요.",
   "prefs.theme_options_reset": "초기화",
   "prefs.theme_options_unavailable": "이 기기에서는 사용할 수 없음",
   "prefs.timeline_half_hour": "−30분",
@@ -3712,6 +3725,10 @@
   "ui.fillet_setback_least": "{least}보다 크게",
   "ui.fillet_setback_tip": "부드러운 코너 패치가 시작되는 위치: 코너에서 각 모서리를 따른 거리. 기본값은 반지름의 {factor}배. 최소 셋백(셋백 없이 라운드가 만나는 곳, 면이 서로 직각이면 반지름)보다 커야 합니다.",
   "ui.fillet_smooth_radius": "반지름 부드럽게 변화",
+  "ui.fillet_turn": "꺾임",
+  "ui.fillet_turn_mitre": "마이터",
+  "ui.fillet_turn_swept": "회전",
+  "ui.fillet_turn_tip": "두 라운드가 사이의 날카로운 코너 모서리를 돌아가는 곳(보스 밑동의 라운드가 세로 모서리를 도는 곳 등).\n마이터: 라운드가 계속 이어져 마이터로 만납니다.\n회전: 라운드가 코너 모서리에서 멈추고 그 둘레를 돕니다. 코너는 둘 모두에 접하는 토러스입니다. 반지름이 같은 라운드가 곧고 볼록한 코너 모서리를 돌 때만.",
   "ui.fillet_type_choices_tip": "일정한 반지름: 모서리 전체에 하나의 반지름.\n현 길이: 면이 어떤 각도로 만나든 라운드의 폭이 같습니다.\n가변 반지름: 양 끝의 반지름과, 추가하면 모서리를 따라 더.\n곡률 연속: 평면과 만나는 곳에서 반사가 꺾이지 않는 단면(G2).\n스플라인: 모서리를 따라 반지름이 설정한 제어 반지름을 따릅니다.",
   "ui.fillet_type_curvature": "곡률 연속",
   "ui.fillet_type_tip": "모서리를 가로지르는 단면. 곡률 연속: 평면 사이의 곡률 연속(G2) 단면으로, 반사가 면에서 라운드로 꺾임 없이 이어집니다.",

assets/locales/pending/sketch-dimension-window.json

@@ -0,0 +1,110 @@
+{
+  "en": {
+    "dialog.dimension_step_down": "Down by {step}",
+    "dialog.dimension_step_expression": "Only a number steps; an expression stays as typed",
+    "dialog.dimension_step_up": "Up by {step}",
+    "prefs.dimension_step_angle": "What the window's arrows, Up/Down and the wheel add to an angle",
+    "prefs.dimension_step_length": "What the window's arrows, Up/Down and the wheel add to a length",
+    "prefs.dimension_steps": "Window steps",
+    "prefs.dimension_values": "Dimension values",
+    "prefs.dimension_values_note": "Where you type a dimension's value. A window has arrows that step it; the Dimension tool places the text first.",
+    "prefs.dimension_values_view": "In the view",
+    "prefs.dimension_values_window": "In a window"
+  },
+  "ja": {
+    "dialog.dimension_step_down": "{step} 減らす",
+    "dialog.dimension_step_expression": "増減できるのは数値だけです。式はそのまま残ります",
+    "dialog.dimension_step_up": "{step} 増やす",
+    "prefs.dimension_step_angle": "ウィンドウの矢印、上下キー、ホイールで角度に加える量",
+    "prefs.dimension_step_length": "ウィンドウの矢印、上下キー、ホイールで長さに加える量",
+    "prefs.dimension_steps": "ウィンドウの増減量",
+    "prefs.dimension_values": "寸法値の入力",
+    "prefs.dimension_values_note": "寸法値を入力する場所です。ウィンドウでは矢印で値を増減でき、寸法ツールは先に文字を配置します。",
+    "prefs.dimension_values_view": "ビュー内",
+    "prefs.dimension_values_window": "ウィンドウ"
+  },
+  "zh": {
+    "dialog.dimension_step_down": "减少 {step}",
+    "dialog.dimension_step_expression": "只有数字可以增减；表达式保持不变",
+    "dialog.dimension_step_up": "增加 {step}",
+    "prefs.dimension_step_angle": "窗口的箭头、上下方向键和滚轮给角度增减的量",
+    "prefs.dimension_step_length": "窗口的箭头、上下方向键和滚轮给长度增减的量",
+    "prefs.dimension_steps": "窗口步长",
+    "prefs.dimension_values": "尺寸值",
+    "prefs.dimension_values_note": "输入尺寸值的位置。窗口带有可增减数值的箭头；尺寸工具会先放置文字。",
+    "prefs.dimension_values_view": "在视图中",
+    "prefs.dimension_values_window": "在窗口中"
+  },
+  "de": {
+    "dialog.dimension_step_down": "Um {step} verringern",
+    "dialog.dimension_step_expression": "Nur eine Zahl lässt sich schrittweise ändern; ein Ausdruck bleibt, wie er eingegeben ist",
+    "dialog.dimension_step_up": "Um {step} erhöhen",
+    "prefs.dimension_step_angle": "Was die Pfeile des Fensters, Auf/Ab und das Mausrad zu einem Winkel addieren",
+    "prefs.dimension_step_length": "Was die Pfeile des Fensters, Auf/Ab und das Mausrad zu einer Länge addieren",
+    "prefs.dimension_steps": "Schritte im Fenster",
+    "prefs.dimension_values": "Bemaßungswerte",
+    "prefs.dimension_values_note": "Wo der Wert einer Bemaßung eingegeben wird. Ein Fenster hat Pfeile, die ihn schrittweise ändern; das Bemaßungswerkzeug platziert zuerst den Text.",
+    "prefs.dimension_values_view": "In der Ansicht",
+    "prefs.dimension_values_window": "In einem Fenster"
+  },
+  "ko": {
+    "dialog.dimension_step_down": "{step} 줄이기",
+    "dialog.dimension_step_expression": "숫자만 증감할 수 있으며 수식은 입력한 그대로 유지됩니다",
+    "dialog.dimension_step_up": "{step} 늘리기",
+    "prefs.dimension_step_angle": "창의 화살표, 위/아래 키와 휠이 각도에 더하는 값",
+    "prefs.dimension_step_length": "창의 화살표, 위/아래 키와 휠이 길이에 더하는 값",
+    "prefs.dimension_steps": "창의 증감 단위",
+    "prefs.dimension_values": "치수 값",
+    "prefs.dimension_values_note": "치수 값을 입력하는 위치입니다. 창에는 값을 증감하는 화살표가 있으며, 치수 도구는 텍스트를 먼저 배치합니다.",
+    "prefs.dimension_values_view": "뷰에서",
+    "prefs.dimension_values_window": "창에서"
+  },
+  "nl": {
+    "dialog.dimension_step_down": "{step} omlaag",
+    "dialog.dimension_step_expression": "Alleen een getal verspringt; een uitdrukking blijft zoals ingevoerd",
+    "dialog.dimension_step_up": "{step} omhoog",
+    "prefs.dimension_step_angle": "Wat de pijlen van het venster, Omhoog/Omlaag en het wieltje bij een hoek optellen",
+    "prefs.dimension_step_length": "Wat de pijlen van het venster, Omhoog/Omlaag en het wieltje bij een lengte optellen",
+    "prefs.dimension_steps": "Stappen in het venster",
+    "prefs.dimension_values": "Maatwaarden",
+    "prefs.dimension_values_note": "Waar de waarde van een maat wordt ingevoerd. Een venster heeft pijlen die de waarde laten verspringen; het maatgereedschap plaatst eerst de tekst.",
+    "prefs.dimension_values_view": "In de weergave",
+    "prefs.dimension_values_window": "In een venster"
+  },
+  "ar": {
+    "dialog.dimension_step_down": "إنقاص بمقدار {step}",
+    "dialog.dimension_step_expression": "يتغير الرقم فقط بالخطوات؛ يبقى التعبير كما كُتب",
+    "dialog.dimension_step_up": "زيادة بمقدار {step}",
+    "prefs.dimension_step_angle": "ما تضيفه أسهم النافذة وأعلى/أسفل والعجلة إلى الزاوية",
+    "prefs.dimension_step_length": "ما تضيفه أسهم النافذة وأعلى/أسفل والعجلة إلى الطول",
+    "prefs.dimension_steps": "خطوات النافذة",
+    "prefs.dimension_values": "قيم الأبعاد",
+    "prefs.dimension_values_note": "مكان كتابة قيمة البعد. للنافذة أسهم تغيّرها بخطوات؛ تضع أداة البعد النص أولًا.",
+    "prefs.dimension_values_view": "في العرض",
+    "prefs.dimension_values_window": "في نافذة"
+  },
+  "he": {
+    "dialog.dimension_step_down": "הפחתה ב־{step}",
+    "dialog.dimension_step_expression": "רק מספר משתנה בצעדים; ביטוי נשאר כפי שנכתב",
+    "dialog.dimension_step_up": "הוספה של {step}",
+    "prefs.dimension_step_angle": "מה שהחצים בחלון, למעלה/למטה והגלגלת מוסיפים לזווית",
+    "prefs.dimension_step_length": "מה שהחצים בחלון, למעלה/למטה והגלגלת מוסיפים לאורך",
+    "prefs.dimension_steps": "צעדי החלון",
+    "prefs.dimension_values": "ערכי מידות",
+    "prefs.dimension_values_note": "היכן מקלידים את ערך המידה. לחלון יש חצים שמשנים אותו בצעדים; כלי המידה מציב קודם את הטקסט.",
+    "prefs.dimension_values_view": "בתצוגה",
+    "prefs.dimension_values_window": "בחלון"
+  },
+  "vi": {
+    "dialog.dimension_step_down": "Giảm {step}",
+    "dialog.dimension_step_expression": "Chỉ số mới thay đổi theo bước; biểu thức giữ nguyên như đã nhập",
+    "dialog.dimension_step_up": "Tăng {step}",
+    "prefs.dimension_step_angle": "Lượng mà mũi tên của cửa sổ, Lên/Xuống và con lăn cộng vào một góc",
+    "prefs.dimension_step_length": "Lượng mà mũi tên của cửa sổ, Lên/Xuống và con lăn cộng vào một độ dài",
+    "prefs.dimension_steps": "Bước của cửa sổ",
+    "prefs.dimension_values": "Giá trị kích thước",
+    "prefs.dimension_values_note": "Nơi bạn nhập giá trị kích thước. Cửa sổ có mũi tên để thay đổi theo bước; công cụ Kích thước đặt văn bản trước.",
+    "prefs.dimension_values_view": "Trong khung nhìn",
+    "prefs.dimension_values_window": "Trong một cửa sổ"
+  }
+}

assets/locales/ru.json

@@ -182,6 +182,8 @@
   "Designs you open or save appear here.": "Здесь появляются открытые и сохранённые дизайны.",
   "Determined by To Object. Choose Angle to edit the angular extent.": "Определяется параметром «До объекта». Выберите «Угол», чтобы задать угловой предел.",
   "Diameter": "Диаметр",
+  "Did this assembly open the wrong way up?": "Эта сборка открылась не той стороной вверх?",
+  "Did this part open the wrong way up?": "Эта деталь открылась не той стороной вверх?",
   "Dimension new shapes": "Проставлять размеры новых фигур",
   "Direction": "Направление",
   "Discard": "Отменить",
@@ -606,6 +608,7 @@
   "Square": "Квадрат",
   "Stand it up": "Поставить вертикально",
   "Stand it up: a quarter turn about X, as one Move feature you can undo.": "Поставить вертикально: четверть оборота вокруг X одной операцией «Переместить», которую можно отменить.",
+  "Stand this assembly up?": "Поставить эту сборку вертикально?",
   "Stand this part up?": "Поставить эту деталь вертикально?",
   "Start angle": "Начальный угол",
   "Start bulge": "Выпуклость в начале",
@@ -1356,6 +1359,7 @@
   "dialog.dimension_insert_hint": "Дважды щёлкните другой управляющий размер, чтобы вставить его имя",
   "dialog.dimension_name": "Размер: {name}",
   "dialog.edit_title": "ИЗМЕНИТЬ: {title}",
+  "dialog.no_shown_body": "Нет отображаемого тела для изменения: покажите тело или выберите «Новое тело»",
   "dialog.pattern_sketch_not_object": "Выберите тела или операции: эскиз — ни то, ни другое. Повторите его кривые собственным инструментом «Массив» или «Зеркало» в эскизе либо сначала выдавите его.",
   "dialog.select": "↖ Выбрать",
   "dialog.selected_count": "↖ Выбрано: {count}",
@@ -1717,6 +1721,8 @@
   "help.view.spin": "Непрерывно вращает вид вокруг модели до следующего щелчка или нажатия клавиши. Используйте, чтобы показать модель со всех сторон.",
   "help.view.tool": "Закрепляет инструмент камеры (орбиту, панорамирование или масштаб), так что перетаскивание левой кнопкой мыши двигает вид, пока вы его не отключите. Используйте на трекпаде или без средней кнопки мыши.",
   "help.view.visual_style": "Переключает способ отрисовки модели: тонированная с рёбрами или без них, каркас или со скрытыми рёбрами. Используйте каркас, чтобы заглянуть внутрь, а тонированный вид — для чистого вида.",
+  "history.sketch_under_constrained": "Недоопределён (степеней свободы: {count})",
+  "history.sketch_under_constrained_one": "Недоопределён ({count} степень свободы)",
   "hole_presets.confirm_delete": "Подтвердить удаление",
   "hole_presets.delete": "Удалить",
   "hole_presets.delete_prompt": "Удалить этот личный пресет? Существующие отверстия не изменятся.",
@@ -2128,6 +2134,8 @@
   "prefs.anti_aliasing_note": "Сглаживает неровные края.",
   "prefs.applies_on_restart": "Применяется после перезапуска",
   "prefs.assistant": "Ассистент",
+  "prefs.auto_operation": "Выбирать операцию автоматически",
+  "prefs.auto_operation_note": "Выбор «Объединить», «Новое тело» или «Вырезать» по тому, чего касается материал.",
   "prefs.axes": "Оси",
   "prefs.axis": "Ось",
   "prefs.bodies_folders": "Папки тел",
@@ -2349,6 +2357,8 @@
   "prefs.sketch_selection": "Эскиз и выделение",
   "prefs.sketch_selection_heading": "Эскиз и выделение",
   "prefs.sketch_selection_note": "Как работает привязка в эскизах и как щелчки выделяют объекты.",
+  "prefs.sketch_state_icons": "Значки эскизов в цвете их состояния",
+  "prefs.sketch_state_icons_note": "В истории и браузере значок эскиза принимает цвет его состояния (недоопределён, полностью определён или с конфликтом), а подсказка называет это состояние. Выкл.: у всех эскизов одинаковый значок.",
   "prefs.sketch_tab_always": "Всегда показывать вкладку «Эскиз»",
   "prefs.sketch_tab_always_note": "Вкладка «Эскиз» остаётся на ленте сразу после «Модель», пока не открыт ни один эскиз. Её инструменты рисования создают эскиз на выбранной плоскости или грани либо на плоскости, которую вы выберете следом, и сразу включают нужный инструмент.",
   "prefs.sketch_tracking_guides": "Направляющие выравнивания по центру и середине",
@@ -2360,6 +2370,11 @@
   "prefs.source": "Источник",
   "prefs.speed": "Скорость",
   "prefs.stand_up_note": "После открытия файла STEP или IGES с осью Z вверх предлагать повернуть его на четверть оборота вокруг X.",
+  "prefs.stand_up_unknown": "Для файлов из неизвестных программ",
+  "prefs.stand_up_unknown.ask": "Спрашивать в диалоговом окне",
+  "prefs.stand_up_unknown.note": "Показывать уведомление",
+  "prefs.stand_up_unknown.off": "Не предлагать",
+  "prefs.stand_up_unknown_note": "Как делается предложение, когда в файле не указана известная программа.",
   "prefs.status_bar": "Строка состояния",
   "prefs.status_bar_note": "Тонкая полоса вдоль нижнего края окна показывает, что изменяется, состояние открытого эскиза его цветом и единицы дизайна; щелчок по единицам изменяет их. Состояние эскиза при этом больше не показывается в углу вида.",
   "prefs.status_done": "Готово",
@@ -3863,7 +3878,7 @@
   "status.navigation": "Назначение кнопок мыши: {mapping}",
   "status.navigation_tip": "Как мышь двигает вид. Щёлкните, чтобы выбрать другое назначение",
   "status.under_constrained": "Недоопределён (степеней свободы: {count})",
-  "status.under_constrained_one": "Недоопределён (степеней свободы: {count})",
+  "status.under_constrained_one": "Недоопределён ({count} степень свободы)",
   "status.units_tip": "Единицы дизайна. Щёлкните, чтобы изменить",
   "the angle must be a number": "угол должен быть числом",
   "the curves must be in one sketch": "кривые должны быть в одном эскизе",
@@ -3902,8 +3917,10 @@
   "timeline.move_to_group": "Переместить операции в папку",
   "timeline.rename_group": "Переименовать папку операций",
   "timeline.reorder_many": "Изменить порядок операций",
+  "timeline.suppress_features": "Подавить операции",
   "timeline.suppress_folders_tip": "Подавить или снять подавление со всех операций в папках и вложенных папках",
   "timeline.ungroup": "Убрать папки операций",
+  "timeline.unsuppress_features": "Снять подавление с операций",
   "to the face": "до грани",
   "to the next face": "до следующей грани",
   "toolbar.customize_note": "Вкладка {tab}. Отметьте команду, чтобы добавить её кнопку на панель инструментов. Можно также перетащить строку из выпадающего меню панели на панель инструментов, перетащить кнопку за пределы панели для удаления или использовать значок закрепления в строке выпадающего меню.",
@@ -4349,6 +4366,8 @@
   "ui.cancel": "Отмена",
   "ui.canvases": "Подложки",
   "ui.center": "Центр",
+  "ui.center_arc_follows_cursor": "Дуга из центра следует направлению курсора",
+  "ui.center_arc_follows_cursor_tip": "Дуга из центра идёт по часовой стрелке или против неё — в ту сторону, в которую курсор обходит её центр. Выкл.: всегда против часовой стрелки от начальной точки.",
   "ui.centerline": "Осевая линия",
   "ui.chain": "Цепочка",
   "ui.chamfer": "Фаска",
@@ -5160,11 +5179,13 @@
   "update.installed": "SolidCraft {version} установлен. Перезапустите, чтобы использовать его.",
   "update.installer_started": "Установщик запустится после закрытия SolidCraft.",
   "update.later": "Напомнить позже",
+  "update.managed": "Доступно обновление: обновите SolidCraft в {manager}",
   "update.no_notes": "У этого выпуска нет примечаний.",
   "update.package_hint": "Эта копия установлена из {kind}. Скачайте новый пакет, затем установите его командой:",
   "update.prefs_dev": "Это сборка для разработки ({version}): она не проверяет обновления.",
   "update.prefs_flatpak": "Эту копию ({version}) обновляет Flatpak: выполните {command} или воспользуйтесь центром приложений. SolidCraft не проверяет обновления.",
   "update.prefs_label": "Обновления",
+  "update.prefs_managed": "Это SolidCraft {version}, которым управляет {manager}. Проверка запрашивает у GitHub последний релиз и больше ничего не отправляет; обновляйте SolidCraft в {manager}.",
   "update.prefs_note": "Это SolidCraft {version} ({kind}). При проверке у GitHub запрашивается последний выпуск, больше ничего не отправляется.",
   "update.prefs_web": "Перезагрузите страницу, чтобы получить последнюю версию веб-приложения. Если сеть недоступна или обновление не успевает загрузиться, открывается сохранённая версия; незавершённая загрузка продолжится до следующей перезагрузки.",
   "update.refresh_checking": "Проверка наличия новейшего выпуска…",

assets/locales/vi.json

@@ -2265,6 +2265,14 @@
   "prefs.auto_operation_note": "Nối, Vật thể mới hoặc Cắt, tùy vào phần vật liệu tiếp xúc.",
   "prefs.axes": "Các trục tọa độ",
   "prefs.axis": "Trục tọa độ",
+  "prefs.blur_cost": "Chi phí kết xuất tương đối. Nhiều thanh hơn thường có nghĩa là cần xử lý nhiều hơn.",
+  "prefs.blur_device": "Không khả dụng trên thiết bị đồ họa hoặc đường kết xuất này",
+  "prefs.blur_guard": "Chất lượng làm mờ đã giảm để duy trì độ phản hồi của khung hình. Bán kính không thay đổi.",
+  "prefs.blur_off": "Tắt",
+  "prefs.blur_reduce_transparency": "Bị tắt bởi cài đặt Giảm độ trong suốt của hệ thống",
+  "prefs.blur_software": "Không khả dụng với đồ họa phần mềm (gpu-software)",
+  "prefs.blur_source": "Không khả dụng trong chế độ xem không gian làm việc này",
+  "prefs.blur_web": "Không khả dụng trên đường kết xuất web này",
   "prefs.bodies_folders": "Thư mục thân khối",
   "prefs.bodies_folders_always": "Luôn luôn",
   "prefs.bodies_folders_never": "Không bao giờ",
@@ -2650,6 +2658,10 @@
   "prefs.theme_follow_off": "Tắt",
   "prefs.theme_follow_stop": "Dừng theo dõi",
   "prefs.theme_import_hint": "Nhấp để chọn tệp giao diện, thả tệp vào đây, hoặc nhấn Ctrl+V (Cmd+V trên Mac) khi đã sao chép một giao diện",
+  "prefs.theme_notice_dismiss": "Ẩn",
+  "prefs.theme_option_blur": "Làm mờ phía sau bảng",
+  "prefs.theme_option_blur_help": "Làm mờ phía sau các bảng bán trong suốt, tính bằng pixel vật lý. Giá trị 0 là tắt.",
+  "prefs.theme_option_invalid": "Giá trị đã lưu cho {option} không hợp lệ; đang dùng giá trị mặc định của giao diện. Giá trị đã lưu vẫn được giữ lại.",
   "prefs.theme_option_opacity": "Độ đục",
   "prefs.theme_option_opacity_help": "Điều chỉnh độ đục của các bảng nổi. Giới hạn độ đục tối thiểu giúp văn bản luôn dễ đọc trên nền màu của khung nhìn.",
   "prefs.theme_option_tab_colours": "Màu thẻ",
@@ -2658,6 +2670,7 @@
   "prefs.theme_option_tab_fade_ms_help": "Chuyển dần màu của bảng điều khiển và khung nhìn khi đổi thẻ. Đặt thành 0 để chuyển ngay lập tức.",
   "prefs.theme_options_badge": "Tùy chọn",
   "prefs.theme_options_more": "Thêm · {count}",
+  "prefs.theme_options_newer": "Giao diện này yêu cầu phiên bản SolidCraft mới hơn. Sau khi nâng cấp, hãy nhập lại giao diện gốc để khôi phục các định nghĩa tùy chọn.",
   "prefs.theme_options_reset": "Đặt lại",
   "prefs.theme_options_unavailable": "Không khả dụng trên thiết bị này",
   "prefs.theme_paste": "Dán giao diện",
@@ -4941,6 +4954,10 @@
   "ui.fillet_setback_least": "Lớn hơn {least}",
   "ui.fillet_setback_tip": "Nơi mảng góc trơn bắt đầu: khoảng cách dọc theo mỗi cạnh tính từ góc. Mặc định là {factor} × bán kính. Giá trị phải lớn hơn khoảng lùi nhỏ nhất, tại đó các đường bo gặp nhau mà không cần lùi: bằng bán kính khi các mặt vuông góc với nhau.",
   "ui.fillet_smooth_radius": "Thay đổi bán kính trơn",
+  "ui.fillet_turn": "Chỗ rẽ",
+  "ui.fillet_turn_mitre": "Vát góc",
+  "ui.fillet_turn_swept": "Quét vòng",
+  "ui.fillet_turn_tip": "Nơi hai góc lượn rẽ quanh một cạnh góc sắc nằm giữa chúng, ví dụ các góc lượn ở chân một khối lồi tại các cạnh đứng của nó.\nVát góc: các góc lượn kéo dài cho đến khi gặp nhau theo đường vát.\nQuét vòng: các góc lượn dừng ở cạnh góc và quay quanh nó, góc là một mặt xuyến tiếp xúc với cả hai. Chỉ cho các góc lượn cùng bán kính quanh một cạnh góc thẳng và lồi.",
   "ui.fillet_type_choices_tip": "Bán kính không đổi: một bán kính dọc suốt cạnh.\nĐộ dài dây cung: độ rộng ngang đường bo giữ nguyên, bất kể góc gặp nhau của các mặt.\nBán kính thay đổi: một bán kính ở mỗi đầu, và thêm dọc cạnh nếu bạn thêm vào.\nLiên tục độ cong: mặt cắt không làm gãy phản chiếu tại nơi gặp các mặt phẳng (G2).\nSpline: bán kính dọc cạnh theo các bán kính điều khiển bạn đặt.",
   "ui.fillet_type_curvature": "Liên tục độ cong",
   "ui.fillet_type_tip": "Mặt cắt ngang qua cạnh. Liên tục độ cong: mặt cắt liên tục độ cong (G2) giữa các mặt phẳng, nên phản chiếu đi từ các mặt vào đường bo mà không bị gãy.",

assets/locales/zh.json

@@ -2265,6 +2265,14 @@
   "prefs.auto_operation_note": "根据材料接触的对象选择合并、新建实体或切割。",
   "prefs.axes": "坐标轴",
   "prefs.axis": "轴",
+  "prefs.blur_cost": "相对渲染开销。条形越多，通常意味着处理工作越多。",
+  "prefs.blur_device": "此图形设备或渲染路径不支持此功能",
+  "prefs.blur_guard": "已降低模糊质量，以保持画面响应。模糊半径未改变。",
+  "prefs.blur_off": "关闭",
+  "prefs.blur_reduce_transparency": "已被系统的降低透明度设置禁用",
+  "prefs.blur_software": "软件图形渲染不支持此功能 (gpu-software)",
+  "prefs.blur_source": "此工作区视图不支持此功能",
+  "prefs.blur_web": "此网页渲染路径不支持此功能",
   "prefs.bodies_folders": "实体文件夹",
   "prefs.bodies_folders_always": "始终显示",
   "prefs.bodies_folders_never": "不显示",
@@ -2650,6 +2658,10 @@
   "prefs.theme_follow_off": "关闭",
   "prefs.theme_follow_stop": "停止跟随",
   "prefs.theme_import_hint": "单击选择主题文件，拖放到此处，或复制主题后按 Ctrl+V（Mac 上为 Cmd+V）",
+  "prefs.theme_notice_dismiss": "忽略",
+  "prefs.theme_option_blur": "面板背后模糊",
+  "prefs.theme_option_blur_help": "半透明面板背后的模糊程度，以物理像素为单位。0 表示关闭。",
+  "prefs.theme_option_invalid": "{option} 的已保存值无效；正在使用主题默认值。已保存值将予以保留。",
   "prefs.theme_option_opacity": "不透明度",
   "prefs.theme_option_opacity_help": "调整浮动面板的不透明度。最低不透明度限制可确保文字在视口颜色上清晰可读。",
   "prefs.theme_option_tab_colours": "选项卡颜色",
@@ -2658,6 +2670,7 @@
   "prefs.theme_option_tab_fade_ms_help": "切换选项卡时渐变面板和视口颜色。设为零可立即切换。",
   "prefs.theme_options_badge": "选项",
   "prefs.theme_options_more": "更多 · {count}",
+  "prefs.theme_options_newer": "此主题需要更新版本的 SolidCraft。升级后，请重新导入原始主题以恢复其选项定义。",
   "prefs.theme_options_reset": "重置",
   "prefs.theme_options_unavailable": "此设备不支持",
   "prefs.theme_paste": "粘贴主题",
@@ -4941,6 +4954,10 @@
   "ui.fillet_setback_least": "须大于 {least}",
   "ui.fillet_setback_tip": "平滑角点曲面片开始的位置：从角点沿每条边的距离。默认值为半径的 {factor} 倍。必须大于最小后退距离（不后退时圆角相交之处；面相互垂直时即半径）。",
   "ui.fillet_smooth_radius": "半径平滑变化",
+  "ui.fillet_turn": "转角",
+  "ui.fillet_turn_mitre": "斜接",
+  "ui.fillet_turn_swept": "旋转",
+  "ui.fillet_turn_tip": "两个圆角绕过它们之间尖锐的角边处，例如凸台根部的圆角绕过其竖直边。\n斜接：圆角继续延伸，直到以斜接相遇。\n旋转：圆角止于角边并绕它旋转，转角是与两者相切的圆环面。仅用于同一半径的圆角绕过笔直的凸角边时。",
   "ui.fillet_type_choices_tip": "恒定半径：整条边一个半径。\n弦长：无论面以什么角度相交，圆角宽度都相同。\n可变半径：两端各一个半径，添加后沿边还有更多。\n曲率连续：与平面相接处反射没有折痕的截面 (G2)。\n样条：沿边的半径跟随您设置的控制半径。",
   "ui.fillet_type_curvature": "曲率连续",
   "ui.fillet_type_tip": "横跨边的截面。曲率连续：平面之间的曲率连续 (G2) 截面，反射从面平滑过渡到圆角，没有折痕。",

crates/doc/src/config_certificates.rs

@@ -393,6 +393,8 @@ pub(crate) struct ExactSketchCurves<'a> {
     /// Each analytic curve's id, whether it is projected (linked) reference geometry, and its
     /// segments.
     segments: Vec<(&'a str, bool, Vec<Seg2>)>,
+    /// Each free-form curve's id (ellipses, conics, splines) and its exact segments.
+    free_form: Vec<(&'a str, Vec<Seg2>)>,
 }
 
 impl<'a> ExactSketchCurves<'a> {
@@ -400,10 +402,17 @@ impl<'a> ExactSketchCurves<'a> {
     /// and segment allocation must not be repeated for every generated face.
     pub(crate) fn new(sketch: &'a SolvedSketch) -> Self {
         let mut segments = Vec::new();
+        let mut free_form = Vec::new();
         if sketch.sketch.curves.len() > 2000 {
-            return Self { segments };
+            return Self { segments, free_form };
         }
         for (index, curve) in sketch.sketch.curves.iter().enumerate() {
+            if !curve.construction
+                && let Some(exact) = sketch.sketch.exact_segs(index)
+            {
+                free_form.push((curve.id.as_str(), exact));
+                continue;
+            }
             if curve.construction
                 || !matches!(
                     curve.kind,
@@ -425,7 +434,21 @@ impl<'a> ExactSketchCurves<'a> {
             };
             segments.push((curve.id.as_str(), curve.link.is_some(), originals));
         }
-        Self { segments }
+        Self { segments, free_form }
+    }
+
+    /// The one free-form sketch curve (an ellipse, conic or spline) a generated segment is a
+    /// whole piece of, either way round: one of the exact segments the curve is made of. A
+    /// segment two curves share stays ambiguous.
+    pub(crate) fn find_free_form(&self, generated: &Seg2) -> Option<String> {
+        let reversed = generated.reversed();
+        let mut found: Option<Option<&str>> = None;
+        for (id, originals) in &self.free_form {
+            if originals.iter().any(|original| *original == *generated || *original == reversed) {
+                found = Some(if found.is_some() { None } else { Some(*id) });
+            }
+        }
+        found.flatten().map(str::to_owned)
     }
 
     /// The one sketch curve a generated segment lies on. A curve drawn over projected

crates/doc/src/document.rs

@@ -734,6 +734,10 @@ pub enum FeatureKind {
         /// from the vertex instead of where the rounds meet (a constant-radius fillet only).
         #[serde(default, skip_serializing_if = "Vec::is_empty")]
         setbacks: Vec<CornerSetback>,
+        /// How two rounds turn where they meet at a sharp side edge: in a mitre (the default) or
+        /// swept round it (a constant-radius, exact, rolling-corner fillet without setbacks only).
+        #[serde(default, skip_serializing_if = "FilletTurn::is_mitre")]
+        turn: FilletTurn,
         /// Round each picked edge's tangent chain with it (the default: edges continuing it
         /// smoothly at its ends, as far as they go), or only the picked edges.
         #[serde(default = "yes", skip_serializing_if = "is_yes")]
@@ -1971,6 +1975,38 @@ impl FilletCorner {
     }
 }
 
+/// How two constant rounds of one radius turn round a sharp, straight, convex side edge square to
+/// both on a plane, such as the rounds along a boss's base at its upright edges.
+#[derive(Clone, Copy, Debug, Default, PartialEq, Eq, Serialize, Deserialize)]
+#[serde(rename_all = "snake_case")]
+pub enum FilletTurn {
+    /// The rounds run on to where they cross and meet in a mitre.
+    #[default]
+    Mitre,
+    /// The rounds end at the side edge and the corner is their section revolved about it, a
+    /// torus tangent to both (`solidcraft_kernel::FilletTurn::Swept`).
+    Swept,
+}
+
+/// Why a swept turn is refused with a fillet's other options: the kernel sweeps the turn of two
+/// constant rounds of one radius, at its own corners only.
+pub const SWEPT_TAKES: &str = "a swept corner turns two constant rounds of one radius: `turn: swept` takes `type: constant`, \
+`corner: rolling`, no `setbacks` and `fit: exact` or `reduce`";
+
+impl FilletTurn {
+    pub fn is_mitre(&self) -> bool {
+        *self == FilletTurn::Mitre
+    }
+
+    /// The kernel's turn.
+    pub fn kernel(self) -> solidcraft_kernel::FilletTurn {
+        match self {
+            FilletTurn::Mitre => solidcraft_kernel::FilletTurn::Mitre,
+            FilletTurn::Swept => solidcraft_kernel::FilletTurn::Swept,
+        }
+    }
+}
+
 /// How Extend continues a surface past its edges.
 #[derive(Clone, Copy, Debug, Default, PartialEq, Eq, Serialize, Deserialize)]
 #[serde(rename_all = "snake_case")]

crates/doc/src/eval.rs

@@ -409,13 +409,14 @@ fn fillet_fitted(
     edges: &[Vec3],
     r: f64,
     fit: crate::FilletFit,
+    turn: kernel::FilletTurn,
 ) -> std::result::Result<(kernel::Body, Option<Vec<f64>>, Vec<Vec3>), kernel::KernelError> {
-    match kernel::fillet_removing(body, edges, r) {
+    match kernel::fillet_removing(body, edges, r, turn) {
         Ok((b, gone)) => Ok((b, None, gone)),
         Err(kernel::KernelError::TooLarge(why)) if fit == crate::FilletFit::Exact => {
-            Err(with_largest_fit(why, "radius", || kernel::fillet_max(body, edges, r)))
+            Err(with_largest_fit(why, "radius", || kernel::fillet_max(body, edges, r, turn)))
         }
-        Err(kernel::KernelError::TooLarge(why)) if fit == crate::FilletFit::Reduce => match kernel::fillet_max_each(body, edges, r)? {
+        Err(kernel::KernelError::TooLarge(why)) if fit == crate::FilletFit::Reduce => match kernel::fillet_max_each(body, edges, r, turn)? {
             // Built at the radius asked for after all (the groups apart): nothing reduced.
             Some((used, b)) => Ok((b, used.iter().any(|u| *u < r).then_some(used), Vec::new())),
             None => Err(kernel::KernelError::TooLarge(why)),
@@ -4014,6 +4015,11 @@ fn blend_body(
 ) -> Result<(Traced, Option<Vec<f64>>, Tapered)> {
     let input = mb.traced();
     let (mut used, mut tapered) = (None, Vec::new());
+    if let FeatureKind::Fillet { turn: crate::FilletTurn::Swept, style, fit, corner, setbacks, .. } = &f.kind
+        && (!style.is_constant() || *fit == crate::FilletFit::Taper || !corner.is_rolling() || !setbacks.is_empty())
+    {
+        return Err(DocError::Invalid(crate::SWEPT_TAKES.into()));
+    }
     // The blended body, and the lineage of what the last blend started from.
     let (nb, from) = match &f.kind {
         // A curvature-continuous fillet's corners are G2 patches, whatever `corner` says: SMLib's
@@ -4061,8 +4067,8 @@ fn blend_body(
             tapered = edges.iter().copied().zip(tapers).filter_map(|(p, t)| Some((p, t?))).collect();
             (b, input)
         }
-        FeatureKind::Fillet { fit, .. } => {
-            let (b, u, gone) = fillet_fitted(&mb.body, edges, r, *fit)?;
+        FeatureKind::Fillet { fit, turn, .. } => {
+            let (b, u, gone) = fillet_fitted(&mb.body, edges, r, *fit, turn.kernel())?;
             if let Some(u) = &u {
                 append_warning(warning, reduced_note(u, r));
             }
@@ -4820,8 +4826,13 @@ fn centered_extrude(
     };
     // Fit cap surfaces in their own coordinates. Fitting a distant world-space
     // wire can tilt an otherwise exact planar cap through numeric cancellation.
-    // A side drawn in collinear pieces is one face (#1788).
-    let bodies = kernel::extrude_whole_sides(&Plane::XY, std::slice::from_ref(region), start, end)?;
+    // A side drawn in collinear pieces is one face (#1788), and so is a side along one ellipse
+    // or spline, whatever pieces the profile holds it in.
+    let curves = sketch.map(crate::config::ExactSketchCurves::new);
+    let one_curve = |s: &solidcore_record::Seg2, t: &solidcore_record::Seg2| {
+        curves.as_ref().is_some_and(|c| c.find_free_form(s).is_some_and(|id| c.find_free_form(t).is_some_and(|other| other == id)))
+    };
+    let bodies = kernel::extrude_whole_sides(&Plane::XY, std::slice::from_ref(region), start, end, &one_curve)?;
     if *plane == Plane::XY {
         return Ok(bodies.into_iter().map(|body| roles.tool(body, None)).collect());
     }
@@ -6318,12 +6329,12 @@ fn replay(
                     let nb = match &src.kind {
                         FeatureKind::Chamfer { distance2, angle, flip, .. } => chamfer_with(vals, &mb.body, &moved, r, distance2, angle, *flip)?,
                         // A copy is congruent to the original: the radius it was reduced to first.
-                        FeatureKind::Fillet { fit, .. } => match st.fitted.get(&src.id) {
+                        FeatureKind::Fillet { fit, turn, .. } => match st.fitted.get(&src.id) {
                             Some(used) => {
                                 let used: Vec<f64> = idx.iter().map(|i| used.get(*i).copied().unwrap_or(r)).collect();
-                                kernel::fillet_each(&mb.body, &moved, &used)?
+                                kernel::fillet_each(&mb.body, &moved, &used, turn.kernel())?
                             }
-                            None => fillet_fitted(&mb.body, &moved, r, *fit)?.0,
+                            None => fillet_fitted(&mb.body, &moved, r, *fit, turn.kernel())?.0,
                         },
                         _ => kernel::fillet(&mb.body, &moved, r)?,
                     };
@@ -8545,6 +8556,7 @@ mod chain_tests {
                 fit: Default::default(),
                 corner: Default::default(),
                 setbacks: Vec::new(),
+                turn: Default::default(),
                 tangent_chain: true,
             },
             None,
@@ -8573,6 +8585,7 @@ mod chain_tests {
             fit: Default::default(),
             corner: Default::default(),
             setbacks: Vec::new(),
+            turn: Default::default(),
             tangent_chain,
         }
     }

crates/doc/src/eval_more.rs

@@ -2318,11 +2318,16 @@ pub(super) fn plastic_eval(doc: &Document, vals: &BTreeMap<String, Value>, f: &F
                 _ => false,
             };
             let (Some(_), Some(_), false) = (outer, openings.first(), alike) else {
+                // A solid box top has no opening: Shell that face first, then pick the rim
+                // around the cavity (#10437).
                 let what = match (loops.len(), openings.len()) {
-                    (0 | 1, _) => "pick the rim face of a shelled body (a face with an inner and an outer edge)".to_string(),
-                    (_, 0) => "pick the rim face of a shelled body: this face's inner edges are where other features stand on it, not an opening"
+                    (0 | 1, _) => "Lip needs the rim of a shelled body: Shell a face open first, then pick the rim around that opening (a face with an outer edge and an inner hole)"
                         .to_string(),
-                    (_, k) => format!("pick the rim face of a shelled body (round one opening): this face has {k} openings alike in size"),
+                    (_, 0) => "Lip needs a rim around an opening: this face's inner edges are where other features stand on it, not a shell cavity. Shell a face open, then pick that rim"
+                        .to_string(),
+                    (_, k) => format!(
+                        "Lip needs one clear opening as the rim: this face has {k} openings alike in size (for example a plate of holes). Shell one cavity, or pick a rim that rings a single opening"
+                    ),
                 };
                 return Err(DocError::Invalid(what));
             };

crates/doc/src/eval_thread.rs

@@ -103,6 +103,11 @@ enum End {
     /// At (or within half a pitch of) an end of the face where material goes on past it, a
     /// shoulder, a head, a blind hole's bottom: the groove stops short, clear of it.
     Closed,
+    /// At an end of an external thread's face where a shoulder starts and stays beyond the face's
+    /// end: the groove runs on through the plane of that end and is trimmed there, so the root
+    /// reaches the shoulder at every angle, a nut bottoms out on it, and nothing past the plane
+    /// is cut.
+    Shoulder,
     /// Inside the face: the groove stops square there.
     Inside,
 }
@@ -121,6 +126,9 @@ pub(super) struct ThreadOn {
     /// A modelled internal thread in a hole wider than it needs: the radius the bore is narrowed
     /// to (the thread's minor radius) before the groove is cut, with the hole's own radius.
     narrow: Option<f64>,
+    /// A shoulder keeps the square stop because the kernel couldn't check whether it stays beyond
+    /// the face's end.
+    shoulder_unchecked: bool,
 }
 
 /// The free-end test of a face's two ends (`side` 0 at its start, 1 at its end), each made
@@ -160,6 +168,22 @@ impl FaceEnds<'_> {
         }
         Ok(free)
     }
+
+    /// Does the shoulder at this closed end stay beyond the plane of the face's end? Not where it
+    /// rises back along the face (a slanted plate, a boss on a round body), which a groove
+    /// running to that plane would cut into: there is material outside the face just inside it.
+    /// The caller keeps the square stop, and says so, when the kernel can't make the check.
+    fn clear_of_end_plane(&self, side: usize) -> Result<bool> {
+        #[cfg(test)]
+        if tests::FAIL_CLEARANCE.get() {
+            return Err(kernel::KernelError::Failed("clearance refused for the test".into()).into());
+        }
+        let (p, e) = (self.pitch, self.pitch * 1e-3);
+        let inside = if side == 0 { (self.cyl.start + e, self.cyl.start + p) } else { (self.cyl.end - p, self.cyl.end - e) };
+        // All the radii the groove cuts beyond the face; only touching their rims is not in its
+        // way, as in `free`.
+        kernel::material_in_ring(self.body, self.cyl, self.beyond.0 + e, self.beyond.1 - e, inside).map(|hit| !hit).map_err(DocError::from)
+    }
 }
 
 /// A thread on the cylindrical face at `p`: its size, and the part of the face it runs over.
@@ -333,11 +357,23 @@ pub(super) fn thread_on(st: &ModelState, feature: u64, p: Vec3, ask: &ThreadAsk)
     // How each end of the thread meets the face: at a face end, or within half a pitch (and its
     // runout) of one, where the groove would reach past it, that end's free-end test decides.
     let near = |at: f64, side: usize| if side == 0 { at - lo } else { hi - at } < pitch / 2.0 + ease.get(side).copied().unwrap_or(0.0);
+    // A shoulder whose check the kernel couldn't make keeps the square stop, and the feature says so.
+    let mut unchecked = false;
     let mut kind = |at: f64, side: usize| -> Result<End> {
         Ok(if !ask.modeled || !near(at, side) {
             End::Inside
         } else if !ends.free(side)? {
-            End::Closed
+            let at_end = (if side == 0 { at - lo } else { hi - at }) < pitch * 1e-3;
+            let square = ease.get(side).copied().unwrap_or(0.0) == 0.0;
+            let clear = at_end && square && !cyl.internal && !form.is_taper() && {
+                let check = ends.clear_of_end_plane(side);
+                unchecked |= matches!(check, Err(DocError::Kernel(_)));
+                match check {
+                    Err(DocError::Kernel(_)) => false,
+                    other => other?,
+                }
+            };
+            if clear { End::Shoulder } else { End::Closed }
         } else if (if side == 0 { at - lo } else { hi - at }) < pitch * 1e-3 {
             End::Free
         } else {
@@ -373,7 +409,7 @@ pub(super) fn thread_on(st: &ModelState, feature: u64, p: Vec3, ask: &ThreadAsk)
         .then(|| form.groove(major, pitch, true))
         .filter(|g| !(g.root_r - cyl.radius >= g.basic_depth / 4.0))
         .map(|g| g.crest_r);
-    Ok(ThreadOn { info, cyl, ends, steep: ask.steep, ease, from: side, narrow })
+    Ok(ThreadOn { info, cyl, ends, steep: ask.steep, ease, from: side, narrow, shoulder_unchecked: unchecked })
 }
 
 /// The end of the face (0: its start, 1: its end) a thread of limited length starts at: the end
@@ -536,7 +572,9 @@ fn thread_grooves(
     // Past a free end of the face the groove runs out into the air, a pitch beyond it. Before
     // a closed one it stops with its section clear of the face's end (its centre as far inside
     // as the section reaches that way), so it never cuts into the shoulder there; inside the
-    // face it stops square at the threaded length's end.
+    // face it stops square at the threaded length's end. At a shoulder it can be trimmed against
+    // ([`End::Shoulder`]) its whole section runs past the plane of the face's end, so every angle
+    // of the last turn is cut down to that plane ([`trim_at_shoulders`] takes off the rest).
     //
     // A runout `e` at an end (ISO 3508) fades the groove out over `e`: its section moves out of
     // the material (an external thread's away from the axis, past the surface; an internal
@@ -548,12 +586,14 @@ fn thread_grooves(
         (End::Free, false) => t.start - p,
         (End::Free, true) => t.start,
         (End::Closed, _) => (t.start - ease[0]).max(face.0 + w_lo),
+        (End::Shoulder, _) => face.0 - w_hi - 0.1 * p,
         (End::Inside, _) => t.start - ease[0],
     };
     let s1 = match (ends[1], ease[1] > 0.0) {
         (End::Free, false) => t.end + p,
         (End::Free, true) => t.end,
         (End::Closed, _) => (t.end + ease[1]).min(face.1 - w_hi),
+        (End::Shoulder, _) => face.1 + w_lo + 0.1 * p,
         (End::Inside, _) => t.end + ease[1],
     };
     if !(s1 - s0 > p * 1e-3) {
@@ -698,6 +738,24 @@ fn taper_envelope(t: &ThreadInfo, radius: f64, ends: [End; 2], (d0, from): (f64,
     Ok(ring.pop())
 }
 
+/// The groove with what runs past a shoulder's plane taken off ([`End::Shoulder`]), so cutting it
+/// leaves the shoulder whole.
+fn trim_at_shoulders(mut tool: Body, axis: Vec3, ends: [End; 2], face: (f64, f64), k: UnitVec3) -> Result<Body> {
+    for (end, at, keep_positive) in [(ends[0], face.0, true), (ends[1], face.1, false)] {
+        if end != End::Shoulder {
+            continue;
+        }
+        let plane = Plane::from_normal(axis + k * at, *k).ok_or_else(|| DocError::Invalid("thread axis".into()))?;
+        // An error of the cut, like the kernel's own: `cut` then falls back to the square stop.
+        let missed = || kernel::KernelError::Failed("the thread's groove misses its face".into());
+        let kept = kernel::half_space(&tool, &plane, keep_positive)?.0;
+        #[cfg(test)]
+        let kept = kept.filter(|_| !tests::EMPTY_TRIM.get());
+        tool = kept.ok_or_else(missed)?;
+    }
+    Ok(tool)
+}
+
 /// Evaluate a thread feature: a cosmetic thread is listed in the model's threads, a modelled
 /// one cut into its body.
 pub(super) fn eval(doc: &Document, vals: &BTreeMap<String, Value>, f: &Feature, st: &mut ModelState, warning: &mut Option<String>) -> Result<()> {
@@ -768,7 +826,13 @@ pub(super) fn eval(doc: &Document, vals: &BTreeMap<String, Value>, f: &Feature,
             None => note,
         });
     }
-    cut(st, on, (*tip, angle, depth))
+    if let Some(note) = cut(st, on, (*tip, angle, depth))? {
+        *warning = Some(match warning.take() {
+            Some(w) => format!("{w}; {note}"),
+            None => note,
+        });
+    }
+    Ok(())
 }
 
 /// A runout as (mm, pitches): ISO 3508's standard 2.5 P and short 1.25 P, or a length.
@@ -783,9 +847,10 @@ pub(super) fn runout(vals: &BTreeMap<String, Value>, e: &Option<crate::ThreadRun
 
 /// Cut a modelled thread resolved on its face into its body: the grooves (SMLib's exact screw
 /// sweeps, a taper's crests by its envelope) by one B-rep boolean, then the chamfered tip
-/// (`tip`, with its angle and depth when given).
-pub(super) fn cut(st: &mut ModelState, on: ThreadOn, (tip, angle, depth): (ThreadTip, Option<f64>, Option<f64>)) -> Result<()> {
-    let ThreadOn { info: t, cyl, ends, steep, ease, from: from_side, narrow } = on;
+/// (`tip`, with its angle and depth when given). What the user should be told about the result, if
+/// anything, is returned.
+pub(super) fn cut(st: &mut ModelState, on: ThreadOn, (tip, angle, depth): (ThreadTip, Option<f64>, Option<f64>)) -> Result<Option<String>> {
+    let ThreadOn { info: t, cyl, ends, steep, ease, from: from_side, narrow, shoulder_unchecked } = on;
     let i = st.bodies.iter().position(|b| b.name == t.body).ok_or_else(|| DocError::Invalid("threaded body".into()))?;
     let Some(mb) = st.bodies.get(i).cloned() else { return Err(DocError::Invalid("body".into())) };
     let (mut input, radius) = (mb.traced(), cyl.radius);
@@ -822,21 +887,46 @@ pub(super) fn cut(st: &mut ModelState, on: ThreadOn, (tip, angle, depth): (Threa
         }
         false => None,
     };
-    let mut grooves = Vec::new();
-    for g in thread_grooves(&t, groove_radius, (cyl.start, cyl.end), ends, steep, ease, taper)? {
-        let section = Region2 { outer: solidcore_record::Loop2::polygon(&g.section), holes: Vec::new() };
-        grooves.push(kernel::sweep_helix_radial(&g.plane, &section, g.base, g.axis, g.pitch, g.turns, &g.law)?);
-    }
-    if let Some(taper) = taper
-        && let Some(envelope) = taper_envelope(&t, radius, ends, taper)?
-    {
-        grooves.push(envelope);
-    }
-    let tool = match grooves.as_slice() {
-        [one] => one.clone(),
-        many => kernel::union_all(&many.iter().collect::<Vec<_>>())?,
+    let cut_grooves = |ends: [End; 2]| -> Result<(Option<Body>, usize)> {
+        let mut grooves = Vec::new();
+        for g in thread_grooves(&t, groove_radius, (cyl.start, cyl.end), ends, steep, ease, taper)? {
+            let section = Region2 { outer: solidcore_record::Loop2::polygon(&g.section), holes: Vec::new() };
+            grooves.push(kernel::sweep_helix_radial(&g.plane, &section, g.base, g.axis, g.pitch, g.turns, &g.law)?);
+        }
+        if let Some(taper) = taper
+            && let Some(envelope) = taper_envelope(&t, radius, ends, taper)?
+        {
+            grooves.push(envelope);
+        }
+        let tool = match grooves.as_slice() {
+            [one] => one.clone(),
+            many => kernel::union_all(&many.iter().collect::<Vec<_>>())?,
+        };
+        let tool = trim_at_shoulders(tool, t.axis_point, ends, (cyl.start, cyl.end), t.axis)?;
+        let cut = kernel::boolean(&input.body, &tool, BoolOp::Cut)?;
+        // Now rather than at the feature's end, where it could only fail the feature.
+        if ends.contains(&End::Shoulder)
+            && let Some(body) = &cut
+        {
+            kernel::check_kept(body)?;
+        }
+        Ok((cut, tool.face_count()))
     };
-    let (nb, groove_faces) = (kernel::boolean(&input.body, &tool, BoolOp::Cut)?, tool.face_count());
+    // A design that built with the square stop keeps building: where the kernel can't make the
+    // trimmed cut, the groove stops clear of the shoulder as it did, and the feature says so.
+    let mut made = cut_grooves(ends);
+    let mut square_stop = shoulder_unchecked;
+    if matches!(made, Err(DocError::Kernel(_))) && ends.contains(&End::Shoulder) {
+        made = cut_grooves(ends.map(|e| if e == End::Shoulder { End::Closed } else { e }));
+        square_stop = true;
+    }
+    let note = (square_stop && made.is_ok()).then(|| {
+        format!(
+            "the {} thread's groove could not be run down to the shoulder here, so it stops clear of it and its last turn is left uncut",
+            t.designation
+        )
+    });
+    let (nb, groove_faces) = made?;
     let nb = nb.ok_or_else(|| DocError::Invalid("the thread removed everything".into()))?;
     // The groove's faces have no role to name them by.
     let groove = crate::lineage::Lineage::unnamed_faces(groove_faces);
@@ -854,7 +944,7 @@ pub(super) fn cut(st: &mut ModelState, on: ThreadOn, (tip, angle, depth): (Threa
     if let Some(slot) = st.bodies.get_mut(i) {
         *slot = ModelBody::traced_new(mb.name, nb, mb.feature);
     }
-    Ok(())
+    Ok(note)
 }
 
 /// The chamfered tip of an external thread (ISO 4753, chamfered end CH) at the free ends `tip`
@@ -937,3 +1027,99 @@ fn tip_cones(
     }
     Ok(out)
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use std::cell::Cell;
+
+    thread_local! {
+        /// Make [`trim_at_shoulders`] find nothing of the groove left.
+        pub(super) static EMPTY_TRIM: Cell<bool> = const { Cell::new(false) };
+        /// Make the rising-shoulder check fail as the kernel would.
+        pub(super) static FAIL_CLEARANCE: Cell<bool> = const { Cell::new(false) };
+    }
+
+    fn ask() -> ThreadAsk<'static> {
+        ThreadAsk {
+            form: None,
+            designation: Some("M10"),
+            hand: ThreadHand::Right,
+            starts: 1,
+            steep: SteepFlank::default(),
+            extent: Extent::Full,
+            from: None,
+            modeled: true,
+            ease_out: (0.0, 0.0),
+            tapped: false,
+            old_auto_size: false,
+        }
+    }
+
+    /// How a thread's ends meet the face at (5, 0, z) of `body`.
+    fn ends_of(body: Body, z: f64) -> [End; 2] {
+        let mut st = ModelState::default();
+        st.bodies.push(ModelBody::new("Part".into(), body, 1));
+        thread_on(&st, 1, Vec3::new(5.0, 0.0, z), &ask()).unwrap().ends
+    }
+
+    /// A shoulder that stays beyond the face's end takes the trim. One rising back along the face
+    /// (a slanted plate, a boss on a round body) keeps the square stop.
+    #[test]
+    fn only_a_shoulder_that_stays_beyond_the_faces_end_takes_the_trim() {
+        let z = Vec3::new(0.0, 0.0, 1.0);
+        let join = |a: &Body, b: &Body| kernel::boolean(a, b, BoolOp::Union).unwrap().unwrap();
+        let boss = kernel::cylinder(Vec3::new(0.0, 0.0, 2.0), z, 5.0, 26.0).unwrap();
+        let plate = kernel::box_solid(Vec3::new(-20.0, -20.0, -6.0), Vec3::new(20.0, 20.0, 2.0)).unwrap();
+        let flat = ends_of(join(&plate, &boss), 20.0);
+        assert!(flat.contains(&End::Shoulder), "{flat:?}");
+        let tilted = kernel::cylinder(Vec3::new(0.0, 0.0, 0.0), Vec3::new(0.2, 0.0, 1.0), 20.0, 6.0).unwrap();
+        let slanted = ends_of(join(&tilted, &boss), 20.0);
+        assert!(slanted.contains(&End::Closed) && !slanted.contains(&End::Shoulder), "{slanted:?}");
+        let round = kernel::cylinder(Vec3::new(0.0, -20.0, 0.0), Vec3::new(0.0, 1.0, 0.0), 10.0, 40.0).unwrap();
+        let on_round = ends_of(join(&round, &boss), 20.0);
+        assert!(on_round.contains(&End::Closed) && !on_round.contains(&End::Shoulder), "{on_round:?}");
+    }
+
+    /// Where the kernel can't check the shoulder, the thread still builds with the square stop, and
+    /// the feature says its last turn is left uncut.
+    #[test]
+    fn a_shoulder_the_kernel_cannot_check_keeps_the_square_stop_and_says_so() {
+        let plate = kernel::box_solid(Vec3::new(-20.0, -20.0, 0.0), Vec3::new(20.0, 20.0, 6.0)).unwrap();
+        let boss = kernel::cylinder(Vec3::new(0.0, 0.0, 6.0), Vec3::new(0.0, 0.0, 1.0), 5.0, 16.0).unwrap();
+        let body = kernel::boolean(&plate, &boss, BoolOp::Union).unwrap().unwrap();
+        let mut st = ModelState::default();
+        st.bodies.push(ModelBody::new("Part".into(), body, 1));
+        FAIL_CLEARANCE.set(true);
+        let on = thread_on(&st, 1, Vec3::new(5.0, 0.0, 14.0), &ask());
+        FAIL_CLEARANCE.set(false);
+        let on = on.unwrap();
+        assert!(on.ends.contains(&End::Closed) && !on.ends.contains(&End::Shoulder), "{:?}", on.ends);
+        let note = cut(&mut st, on, (ThreadTip::None, None, None)).unwrap();
+        assert!(note.is_some_and(|n| n.contains("M10") && n.contains("left uncut")));
+    }
+
+    /// Where the trim leaves nothing of the groove, a thread at a shoulder that built with the
+    /// square stop still builds with it, and the feature says its last turn is left uncut.
+    #[test]
+    fn a_shoulder_cut_the_kernel_refuses_falls_back_to_the_square_stop_and_says_so() {
+        let plate = kernel::box_solid(Vec3::new(-20.0, -20.0, 0.0), Vec3::new(20.0, 20.0, 6.0)).unwrap();
+        let boss = kernel::cylinder(Vec3::new(0.0, 0.0, 6.0), Vec3::new(0.0, 0.0, 1.0), 5.0, 16.0).unwrap();
+        let body = kernel::boolean(&plate, &boss, BoolOp::Union).unwrap().unwrap();
+        let build = |fail: bool| {
+            let mut st = ModelState::default();
+            st.bodies.push(ModelBody::new("Part".into(), body.clone(), 1));
+            let on = thread_on(&st, 1, Vec3::new(5.0, 0.0, 14.0), &ask()).unwrap();
+            EMPTY_TRIM.set(fail);
+            let note = cut(&mut st, on, (ThreadTip::None, None, None));
+            EMPTY_TRIM.set(false);
+            (note.unwrap(), kernel::measure(&st.bodies[0].body).unwrap().volume)
+        };
+        let (none, trimmed) = build(false);
+        assert_eq!(none, None);
+        let (note, square) = build(true);
+        assert!(note.is_some_and(|n| n.contains("M10") && n.contains("left uncut")));
+        // The square stop leaves about half a pitch's worth of groove uncut: well over a mm³.
+        assert!(square > trimmed + 1.0, "{square} vs {trimmed}");
+    }
+}

crates/doc/src/format/pending/fillet-turn.rs

@@ -0,0 +1,5 @@
+//! A fillet saves `turn: "swept"` when two of its rounds that turn round a sharp side edge (the
+//! rounds along a boss's base, at its upright edges) are swept round that edge, their corner an
+//! exact torus; absent, the default `mitre`, they meet in a mitre, as designs before this change were
+//! built. An older design has none and keeps its mitres. The last release refuses a design with
+//! this change (the newer format number).

crates/doc/src/lineage.rs

@@ -239,7 +239,10 @@ impl<'a> ProfileRoles<'a> {
         // Every curve the segment is drawn on (one, or several coincident or collinear ones).
         let curve = |segment: usize| -> Vec<String> {
             let (Some(curves), Some(segment)) = (curves.as_ref(), segments.get(segment)) else { return Vec::new() };
-            let drawn: Vec<String> = curves.find_all_along(segment).into_iter().map(|id| format!("side:{id}")).collect();
+            let mut drawn: Vec<String> = curves.find_all_along(segment).into_iter().map(|id| format!("side:{id}")).collect();
+            if drawn.is_empty() {
+                drawn.extend(curves.find_free_form(segment).map(|id| format!("side:{id}")));
+            }
             match self.thin {
                 // A thin wall's side beside its curve (the other side may lie on it).
                 Some(thin) if drawn.is_empty() => curves.find_offset(segment, &thin.curves, thin.distances),

crates/doc/src/tests.rs

@@ -295,6 +295,7 @@ fn box_fillet_cut_timeline() {
             fit: Default::default(),
             corner: Default::default(),
             setbacks: Vec::new(),
+            turn: Default::default(),
             tangent_chain: true,
         },
         None,
@@ -370,6 +371,7 @@ fn errors_are_reported_not_fatal() {
             fit: Default::default(),
             corner: Default::default(),
             setbacks: Vec::new(),
+            turn: Default::default(),
             tangent_chain: true,
         },
         None,
@@ -867,12 +869,39 @@ fn fillet_setbacks_default_to_none_and_round_trip() {
         fit: Default::default(),
         corner: Default::default(),
         setbacks: vec![CornerSetback { vertex: Position(Vec3::new(60.0, 40.0, 20.0)), distance: "8 mm".into() }],
+        turn: Default::default(),
         tangent_chain: true,
     };
     let back: FeatureKind = serde_json::from_value(serde_json::to_value(&set).unwrap()).unwrap();
     assert_eq!(back, set);
 }
 
+/// A fillet saved before turns reads as mitred and writes no `turn`; a swept one saves
+/// `turn: "swept"` and keeps it through a save and an open; a turn of another name is refused.
+#[test]
+fn fillet_turn_defaults_to_mitre_round_trips_and_refuses_unknown_turns() {
+    let old = serde_json::json!({"type": "fillet", "edges": [[15.0, 0.0, 10.0]], "radius": "2"});
+    let kind: FeatureKind = serde_json::from_value(old.clone()).unwrap();
+    let FeatureKind::Fillet { turn, .. } = &kind else { panic!("{kind:?}") };
+    assert_eq!(*turn, crate::FilletTurn::Mitre);
+    assert!(serde_json::to_value(&kind).unwrap().get("turn").is_none());
+    let mut swept = old.clone();
+    swept["turn"] = serde_json::json!("swept");
+    let kind: FeatureKind = serde_json::from_value(swept).unwrap();
+    assert!(matches!(kind, FeatureKind::Fillet { turn: crate::FilletTurn::Swept, .. }), "{kind:?}");
+    assert_eq!(serde_json::to_value(&kind).unwrap()["turn"], "swept");
+    let mut doc = Document::new("turn");
+    doc.add_feature(kind.clone(), None).unwrap();
+    let saved = doc.to_json();
+    let opened = Document::from_json(&saved).unwrap();
+    assert_eq!(opened.features.last().map(|f| &f.kind), Some(&kind));
+    assert_eq!(opened.to_json(), saved);
+    let mut unknown = old;
+    unknown["turn"] = serde_json::json!("round");
+    let e = serde_json::from_value::<FeatureKind>(unknown).unwrap_err().to_string();
+    assert!(e.contains("unknown variant `round`") && e.contains("mitre") && e.contains("swept"), "{e}");
+}
+
 #[test]
 fn timeline_group_legacy_json_omits_empty_joint_membership() {
     let old = serde_json::json!({"id":100, "name":"Folder", "parent":null, "features":[]});
@@ -1056,3 +1085,68 @@ fn feature_kind_key_and_type_name_mappings() {
     assert_eq!(FeatureKind::type_name_to_kind_key("MeshFeature"), Some("mesh_import"));
     assert_eq!(FeatureKind::type_name_to_kind_key("NonExistent"), None);
 }
+
+/// An extruded ellipse has one side face, and a spline in a profile one wall, each named by its
+/// sketch curve alone (no piece number): the same names on a second build and after reopening.
+#[test]
+fn an_extruded_ellipse_or_spline_is_one_wall_named_by_its_curve() {
+    let extrude = |sketch: u64| FeatureKind::Extrude {
+        thin: None,
+        sketch: crate::SketchId(sketch),
+        profiles: ProfileSel::All,
+        extent: Extent {
+            convention: crate::ExtrudeConvention::LegacyPerSide,
+            distance: "20".into(),
+            direction: Direction::Positive,
+            distance2: None,
+            start_offset: None,
+            through_all: false,
+            taper: None,
+            corner: Default::default(),
+            to: None,
+            to_offset: None,
+            from: None,
+            to_body_apart: false,
+        },
+        operation: Operation::NewBody,
+        targets: vec![],
+    };
+    for spline in [false, true] {
+        let mut sk = Sketch::new();
+        let curve = if spline {
+            let pts: Vec<usize> =
+                [(0., 0.), (10., -3.), (20., 4.), (30., 0.)].iter().map(|&(x, y)| sk.add_point(Vec2::new(x, y), None).unwrap()).collect();
+            let (a, b) = (sk.add_point(Vec2::new(30., 20.), None).unwrap(), sk.add_point(Vec2::new(0., 20.), None).unwrap());
+            let curve = sk
+                .add_curve(solidcraft_sketch::CurveKind::Spline { pts: pts.clone(), control: false, degree: 3, periodic: false, nurbs: None }, None)
+                .unwrap();
+            sk.add_line_pts(pts[3], a, None).unwrap();
+            sk.add_line_pts(a, b, None).unwrap();
+            sk.add_line_pts(b, pts[0], None).unwrap();
+            curve
+        } else {
+            let m = sk.add_point(Vec2::new(10., 0.), None).unwrap();
+            sk.add_curve(solidcraft_sketch::CurveKind::Ellipse { c: 0, m, r: 5. }, None).unwrap()
+        };
+        let id = sk.curves[curve].id.clone();
+        let mut doc = Document::new("one wall");
+        let s = doc.add_feature(FeatureKind::Sketch { plane: PlaneRef::Origin { name: "XY".into() }, sketch: sk }, None).unwrap();
+        let f = doc.add_feature(extrude(s), None).unwrap();
+        let names = |doc: &Document| {
+            let mut m = Model::new();
+            m.evaluate(doc);
+            assert!(m.results.iter().all(|r| r.error.is_none()), "{:?}", m.results);
+            let st = m.state();
+            let mut names = crate::naming::face_names(&st.bodies[0]).as_ref().clone();
+            names.sort();
+            names
+        };
+        let first = names(&doc);
+        let wall = format!("F{f}:side:{id}");
+        assert_eq!(first.iter().filter(|n| **n == wall).count(), 1, "{first:?}");
+        assert_eq!(first.len(), if spline { 6 } else { 3 }, "{first:?}");
+        assert!(first.iter().all(|n| !n.contains('#')), "no piece names: {first:?}");
+        assert_eq!(names(&doc), first, "a second build");
+        assert_eq!(names(&Document::from_json(&doc.to_json()).unwrap()), first, "reopened");
+    }
+}

crates/doc/src/walk.rs

@@ -54,6 +54,7 @@ impl Walk for solidcraft_kernel::DraftCorner {}
 impl Walk for crate::document::Direction {}
 impl Walk for crate::document::FilletFit {}
 impl Walk for crate::document::FilletCorner {}
+impl Walk for crate::document::FilletTurn {}
 impl Walk for crate::document::MeshData {}
 impl Walk for crate::document::RevolveConvention {}
 impl Walk for crate::document::RailFit {}

crates/engine/src/cmd/clearance.rs

@@ -9,7 +9,7 @@
 use std::collections::{BTreeMap, HashMap};
 use std::sync::Arc;
 
-use serde_json::{Value, json};
+use serde_json::Value;
 use solidcraft_geom::mesh_distance::box_gap;
 use solidcraft_geom::prelude::*;
 use solidcraft_geom::{Aabb3, Mesh};
@@ -17,9 +17,20 @@ use solidcraft_kernel::{BodyDistance, DistanceShape};
 
 use super::CommandSpec;
 use crate::params::{bad, num, str_, string_list};
+use crate::schema::clearance::{
+    Clearance as ClearanceReply, ClearanceParams, MAX_CLEARANCE, MAX_NEAREST, NearPair, Neighbour, Overlap, OverlapBounds, Unchecked,
+};
+use crate::schema::{TypedContract, output_schema_for};
 use crate::{Result, Session};
 
-pub static COMMANDS: &[CommandSpec] = &[CommandSpec::new("inspect.clearance", "Clearance", clearance).icon("interference").noundo().params(
+const CONTRACT: TypedContract<ClearanceParams> = TypedContract::new();
+
+pub static COMMANDS: &[CommandSpec] = &[CommandSpec::new("inspect.clearance", "Clearance", crate::checked!("inspect.clearance", clearance))
+    .icon("interference")
+    .noundo()
+    .contract(&CONTRACT)
+    .output(output_schema_for::<ClearanceReply>)
+    .params(
     "bodies?: [names] (default: every solid body, in world placement, but those in `against`; mesh bodies are not measured); against?: [names] (only pairs with one body in `bodies` and the other here); \
      min_volume?: mm³ (default 0.01: smaller overlaps count as contact); clearance?: mm (default 0: report pairs closer than this); \
      nearest?: n (each body of `bodies` gets its n nearest others); skip_within?: \"occurrence\" (pairs of bodies of one occurrence) | \
@@ -34,10 +45,6 @@ pub static COMMANDS: &[CommandSpec] = &[CommandSpec::new("inspect.clearance", "C
 const MAX_BODIES: usize = 20_000;
 /// Most pairs whose grown boxes meet that one call measures.
 const MAX_PAIRS: usize = 200_000;
-/// Most neighbours a body's `nearest` list holds.
-const MAX_NEAREST: usize = 1000;
-/// Largest clearance (mm).
-const MAX_CLEARANCE: f64 = 1e6;
 
 #[derive(Clone, Copy, PartialEq, Eq)]
 enum SkipWithin {
@@ -261,48 +268,56 @@ fn clearance(s: &mut Session, p: &Value) -> Result<Value> {
     for k in ["bodies", "against"] {
         asked.extend(string_list(cmd, p, k)?);
     }
-    let mut unchecked: Vec<Value> = mesh_bodies
+    let mut unchecked: Vec<Unchecked> = mesh_bodies
         .iter()
         .filter(|b| p.get("bodies").is_none_or(Value::is_null) || asked.contains(&b.name))
-        .map(|b| json!({"a": b.name, "b": null, "reason": super::interference::MESH_NOT_CHECKED}))
+        .map(|b| Unchecked { a: b.name.clone(), b: None, reason: super::interference::MESH_NOT_CHECKED.to_string() })
         .collect();
     let name = |i: usize| solid.get(i).map_or("", |b| b.name.as_str());
+    let pair = |i: usize, j: usize, reason: String| Unchecked { a: name(i).to_string(), b: Some(name(j).to_string()), reason };
     for (&(i, j), r) in close.iter().zip(results) {
         let r = match r {
             Ok(r) => r,
             Err(e) => {
-                unchecked.push(json!({"a": name(i), "b": name(j), "reason": e.to_string()}));
+                unchecked.push(pair(i, j, e.to_string()));
                 continue;
             }
         };
         if let Some(reason) = r.unchecked {
-            unchecked.push(json!({"a": name(i), "b": name(j), "reason": reason}));
+            unchecked.push(pair(i, j, reason));
             continue;
         }
         if let Some((volume, area, bbox, center)) = r.overlap
             && volume >= min_volume
         {
-            overlaps.push(json!({"a": name(i), "b": name(j), "volume_mm3": volume, "area_mm2": area,
-                "bbox": {"min": bbox.min, "max": bbox.max}, "center": center}));
+            overlaps.push(Overlap {
+                a: name(i).to_string(),
+                b: name(j).to_string(),
+                volume_mm3: volume,
+                area_mm2: area,
+                bbox: OverlapBounds { min: bbox.min.into(), max: bbox.max.into() },
+                center: center.into(),
+            });
             known.insert((i, j), 0.0);
             continue;
         }
         let Some(d) = r.distance else { continue };
         known.insert((i, j), d.distance);
         if d.distance < gap {
-            let mut e = json!({"a": name(i), "b": name(j), "distance_mm": d.distance, "from": d.from, "to": d.to});
-            if let Some((v, ..)) = r.overlap.filter(|o| o.0 > 0.0) {
-                e["overlap_mm3"] = json!(v);
-            }
-            if !d.exact {
-                e["exact"] = json!(false);
-            }
-            near.push(e);
+            near.push(NearPair {
+                a: name(i).to_string(),
+                b: name(j).to_string(),
+                distance_mm: d.distance,
+                from: d.from.into(),
+                to: d.to.into(),
+                overlap_mm3: r.overlap.filter(|o| o.0 > 0.0).map(|o| o.0),
+                exact: (!d.exact).then_some(false),
+            });
         }
     }
-    near.sort_by(|x, y| x["distance_mm"].as_f64().unwrap_or(0.0).total_cmp(&y["distance_mm"].as_f64().unwrap_or(0.0)));
+    near.sort_by(|x, y| x.distance_mm.total_cmp(&y.distance_mm));
 
-    let mut nearest_out = serde_json::Map::new();
+    let mut nearest_out = BTreeMap::new();
     if nearest > 0 {
         let lists = nearest_lists(&subjects, n, nearest, &boxes, &allowed, &mut known, |pairs| {
             solidcraft_kernel::map_with_local_pools(pairs, usize::MAX, |&(i, j)| {
@@ -311,23 +326,25 @@ fn clearance(s: &mut Session, p: &Value) -> Result<Value> {
             })
         });
         for (i, list) in lists {
-            let rows: Vec<Value> = list.iter().map(|&(j, d)| json!({"body": name(j), "distance_mm": d})).collect();
-            nearest_out.insert(name(i).to_string(), Value::Array(rows));
+            let rows = list.iter().map(|&(j, d)| Neighbour { body: name(j).to_string(), distance_mm: d }).collect();
+            nearest_out.insert(name(i).to_string(), rows);
         }
     }
 
-    Ok(json!({
-        "overlaps": overlaps,
-        "near": near,
-        "nearest": nearest_out,
-        "unchecked": unchecked,
-        "bodies": subjects.len(),
-        "pairs_checked": close.len(),
-        "pairs_reused": reused,
-        "pairs_pruned": total.saturating_sub(close.len()),
-        "truncated": truncated > 0,
-        "ms": started.elapsed().as_secs_f64() * 1000.0,
-    }))
+    let reply = ClearanceReply {
+        overlaps,
+        near,
+        nearest: nearest_out,
+        unchecked,
+        bodies: subjects.len(),
+        pairs_checked: close.len(),
+        pairs_reused: reused,
+        pairs_pruned: total.saturating_sub(close.len()),
+        truncated: truncated > 0,
+        ms: started.elapsed().as_secs_f64() * 1000.0,
+        param_warnings: Vec::new(),
+    };
+    serde_json::to_value(reply).map_err(|e| bad(cmd, e.to_string()))
 }
 
 /// One pair: its overlap when the meshes meet or one holds the other, otherwise its distance

crates/engine/src/cmd/features.rs

@@ -13,8 +13,8 @@ use solidcraft_geom::prelude::*;
 use super::{CommandSpec, not_in_sketch};
 use crate::params::{UNKNOWN_COMMAND, bad, bool_, expr, expr_problem, req_expr, str_, string_list, string_list_or_default, vec2, vec3};
 use crate::schema::features::{
-    BoundingSolidParams, BoxParams, ConeParams, CylinderParams, ExtrudeParams, FeatureNotice, FeatureResult, NoticeAction, OffsetPlaneParams,
-    PipeParams, PlaneAtAngleParams, ScaleParams, SphereParams, TorusParams,
+    AppliedRadius, BoundingSolidParams, BoxParams, ConeParams, CylinderParams, ExtrudeParams, FeatureNotice, FeatureResult, FilletParams,
+    FilletResult, NoticeAction, OffsetPlaneParams, PipeParams, PlaneAtAngleParams, ScaleParams, SphereParams, TorusParams,
 };
 use crate::schema::{TypedContract, output_schema_for};
 use crate::{EngineError, Result, Session};
@@ -30,6 +30,7 @@ const BOUNDING_SOLID_CONTRACT: TypedContract<BoundingSolidParams> = TypedContrac
 const SCALE_CONTRACT: TypedContract<ScaleParams> = TypedContract::new();
 const OFFSET_PLANE_CONTRACT: TypedContract<OffsetPlaneParams> = TypedContract::new();
 const PLANE_AT_ANGLE_CONTRACT: TypedContract<PlaneAtAngleParams> = TypedContract::new();
+const FILLET_CONTRACT: TypedContract<FilletParams> = TypedContract::new();
 
 pub static COMMANDS: &[CommandSpec] = &[
     CommandSpec::new("solid.extrude", "Extrude", crate::checked!("solid.extrude", extrude))
@@ -78,11 +79,13 @@ pub static COMMANDS: &[CommandSpec] = &[
         .contract(&CONE_CONTRACT)
         .output(output_schema_for::<FeatureResult>)
         .params("radius | diameter, height: expr (the base circle, and the top's distance along the axis; a negative height goes the other way); top_radius? | top_diameter?: expr (the top circle; default 0: a full cone ending in an apex); base?: [x,y,z] (centre of the base circle: numbers in mm or length expressions; default: the origin); axis?: X|Y|Z|[x,y,z] (default Z); operation?, touching?, targets?: [body], name?, body_name?"),
-    CommandSpec::new("solid.fillet", "Fillet", fillet)
+    CommandSpec::new("solid.fillet", "Fillet", crate::checked!("solid.fillet", fillet))
         .at("SOLID", "MODIFY")
         .icon("fillet")
         .key("F")
-        .params("edges: [[x,y,z] point on edge | {body, index}] ; radius: expr; tangent_chain?: bool (default true: each picked edge's tangent chain is rounded with it; false: exactly the picked edges); body?; type?: constant|curvature (alias g2: curvature-continuous quintic between planar faces along straight edges, one planar end face at each end (including sloped ends); radius sets the equivalent circular setback, not constant curvature; exact fit only)|chord (radius is the width across)|variable (radius at the end nearest start, radius2 at the other; one end may be 0, where the round closes to the corner)|spline (the radius along the edge is a clamped B-spline from the end nearest start: radius is its first control radius, radii the rest, knots its knot vector from 0 to 1; one end may be 0); radius2?; start?: [x,y,z]; radii?: [expr, …]; knots?: [number, …]; mid?: [[position 0…1 from start, radius expr], …] (variable radii between the ends); smooth?: bool (smooth instead of straight between the radii); corner?: rolling|g2 (rolling, the default: the corners where three blended edges meet are pieces of the rolling ball's sphere, tangent to each blend; a curvature round's corners are always g2 patches, between its own sections; g2: each corner where three or more rounded edges meet, and every edge there is rounded, is set back (1.5 × the radius along each edge unless `setbacks` names it) and filled with a patch meeting the rounds and the faces round it to the second order (curvature-continuous seams, clear of the points where a round's section ends on a face), constant-radius exact fillets only, refused where it cannot be built); setbacks?: [{vertex: [x,y,z], distance: expr}, …] (corner setbacks: the corner at the vertex nearest `vertex`, where every edge meeting it is rounded, starts its patch `distance` along each of those edges from the vertex, past where the rounds would meet (past the radius at a square corner), so the rounds blend through a larger patch; one distance for all of a corner's edges; constant-radius exact fillets only; with `corner: g2`, the G2 patch's corners); fit?: exact|reduce|taper (exact, the default: a radius too large for the geometry around the edges is refused, naming the largest that fits; reduce: where it doesn't fit it is reduced to the largest that does, one radius for edges sharing a face; the smallest used is returned as `radius_applied`, each edge's as `radii_applied: [{edge: [x,y,z], radius}]`, and noted in the feature's warning; taper: along each straight edge between planar faces where it doesn't fit, the radius follows the room there as a smooth spline, down to 0 where a face closes to a point, noted in the feature's warning)"),
+        .contract(&FILLET_CONTRACT)
+        .output(output_schema_for::<FilletResult>)
+        .params("edges: [[x,y,z] point on edge | {body, index}] ; radius: expr; tangent_chain?: bool (default true: each picked edge's tangent chain is rounded with it; false: exactly the picked edges); body?; type?: constant|curvature (alias g2: curvature-continuous quintic between planar faces along straight edges, one planar end face at each end (including sloped ends); radius sets the equivalent circular setback, not constant curvature; exact fit only)|chord (radius is the width across)|variable (radius at the end nearest start, radius2 at the other; one end may be 0, where the round closes to the corner)|spline (the radius along the edge is a clamped B-spline from the end nearest start: radius is its first control radius, radii the rest, knots its knot vector from 0 to 1; one end may be 0); radius2?; start?: [x,y,z]; radii?: [expr, …]; knots?: [number, …]; mid?: [[position 0…1 from start, radius expr], …] (variable radii between the ends); smooth?: bool (smooth instead of straight between the radii); corner?: rolling|g2 (rolling, the default: the corners where three blended edges meet are pieces of the rolling ball's sphere, tangent to each blend; a curvature round's corners are always g2 patches, between its own sections; g2: each corner where three or more rounded edges meet, and every edge there is rounded, is set back (1.5 × the radius along each edge unless `setbacks` names it) and filled with a patch meeting the rounds and the faces round it to the second order (curvature-continuous seams, clear of the points where a round's section ends on a face), constant-radius exact fillets only, refused where it cannot be built); setbacks?: [{vertex: [x,y,z], distance: expr}, …] (corner setbacks: the corner at the vertex nearest `vertex`, where every edge meeting it is rounded, starts its patch `distance` along each of those edges from the vertex, past where the rounds would meet (past the radius at a square corner), so the rounds blend through a larger patch; one distance for all of a corner's edges; constant-radius exact fillets only; with `corner: g2`, the G2 patch's corners); turn?: mitre|swept (where two rounds turn round a sharp, straight, convex side edge square to both on a plane, such as the rounds along a boss's base at its upright edges: mitre, the default, runs them on to meet in a mitre; swept ends them at the side edge and fills the corner with their section revolved about it, a torus; swept takes type: constant, corner: rolling, no setbacks and fit: exact or reduce, and is refused with the reason where the rounds are unequal or the side edge is concave, curved or tangent); fit?: exact|reduce|taper (exact, the default: a radius too large for the geometry around the edges is refused, naming the largest that fits; reduce: where it doesn't fit it is reduced to the largest that does, one radius for edges sharing a face; the smallest used is returned as `radius_applied`, each edge's as `radii_applied: [{edge: [x,y,z], radius}]`, and noted in the feature's warning; taper: along each straight edge between planar faces where it doesn't fit, the radius follows the room there as a smooth spline, down to 0 where a face closes to a point, noted in the feature's warning)"),
     CommandSpec::new("solid.chamfer", "Chamfer", chamfer).at("SOLID", "MODIFY").icon("chamfer").params("edges: [[x,y,z] | {body, index}] ; distance: expr; tangent_chain?: bool (default true: each picked edge's tangent chain is cut with it; false: exactly the picked edges); distance2?: expr (along the second face) | angle?: expr (from the first face); flip?: bool (which face is first: by default the one facing up most); body?"),
     CommandSpec::new("solid.combine", "Combine", combine).at("SOLID", "MODIFY").icon("combine").params("target: body; tools: [body]; operation?: join|cut|intersect; touching?: separate|one_body (what a join makes of pieces that share no face: separate, the default, makes each piece that touches another only along an edge or at a point a body of its own and keeps pieces that touch nothing in one body; one_body keeps every piece in one body); keep_tools?: bool; new_component?: bool (the result goes into a new component; component_name?)"),
     CommandSpec::new("solid.pattern.rectangular", "Rectangular Pattern", pattern_rect)
@@ -1788,6 +1791,15 @@ fn fillet(s: &mut Session, p: &Value) -> Result<Value> {
             return Err(bad(cmd, "`setbacks` are built for a constant-radius fillet (`type: constant`, `fit: exact`) only"));
         }
     }
+    // How two rounds turn at a sharp side edge.
+    let turn = match str_(p, "turn").map(str::to_ascii_lowercase).as_deref() {
+        None | Some("mitre") => solidcraft_doc::FilletTurn::Mitre,
+        Some("swept") => solidcraft_doc::FilletTurn::Swept,
+        Some(o) => return Err(bad(cmd, format!("unknown turn `{o}` (mitre or swept)"))),
+    };
+    if !turn.is_mitre() && (!style.is_constant() || fit == solidcraft_doc::FilletFit::Taper || !corner.is_rolling() || !setbacks.is_empty()) {
+        return Err(bad(cmd, solidcraft_doc::SWEPT_TAKES));
+    }
     let mut out = add_feature(
         s,
         p,
@@ -1799,6 +1811,7 @@ fn fillet(s: &mut Session, p: &Value) -> Result<Value> {
             fit,
             corner,
             setbacks,
+            turn,
             tangent_chain: bool_(p, "tangent_chain").unwrap_or(true),
         },
     )?;
@@ -1808,9 +1821,9 @@ fn fillet(s: &mut Session, p: &Value) -> Result<Value> {
         && let Some(r) = state.fitted_radius(id)
     {
         out["radius_applied"] = serde_json::json!(r);
-        let each: Vec<Value> =
-            state.fitted_edges(id).unwrap_or_default().into_iter().map(|(p, r)| serde_json::json!({"edge": [p.x, p.y, p.z], "radius": r})).collect();
-        out["radii_applied"] = Value::Array(each);
+        let each: Vec<AppliedRadius> =
+            state.fitted_edges(id).unwrap_or_default().into_iter().map(|(p, radius)| AppliedRadius { edge: [p.x, p.y, p.z], radius }).collect();
+        out["radii_applied"] = serde_json::to_value(each).map_err(|e| EngineError::Internal(cmd.into(), e.to_string()))?;
     }
     Ok(out)
 }
@@ -3567,6 +3580,87 @@ mod corner_tests {
         eprintln!("mixed corner g2: {err}");
         assert!(err.contains("not supported yet") && err.contains("(40.000, 20.000, 20.000)") && err.contains("all convex or all concave"), "{err}");
     }
+
+    /// `solid.fillet turn?: mitre|swept` on the four base edges of a 10 x 10 x 5 boss on a
+    /// 40 x 30 x 10 plate, r 1: at each upright boss edge the two rounds turn round it. Each base
+    /// edge gains the spandrel A = (1 - π/4) r² along its 10, and the corners the rounds' part
+    /// beyond both walls, whose section's first moment about the upright edge is
+    /// M = (5/6 - π/4) r³: mitred (the default), 8 M; swept, that section revolved a quarter turn at
+    /// each corner, 2π M, the corner's face the horn torus of radii r, r about the upright edge,
+    /// centred r above the plate. The turn is saved; an unknown turn and a swept chord round are
+    /// refused as parameters, and swept rounds along a pocket's floor (its upright edges concave)
+    /// with the kernel's reason.
+    #[test]
+    fn rounds_turning_round_a_boss_edge_are_mitred_or_swept() {
+        use std::f64::consts::PI;
+        const BASE: [[f64; 3]; 4] = [[20.0, 10.0, 10.0], [25.0, 15.0, 10.0], [20.0, 20.0, 10.0], [15.0, 15.0, 10.0]];
+        let boss = || {
+            let mut s = Session::default();
+            run(&mut s, "solid.box", &json!({"length": 40, "width": 30, "height": 10, "body_name": "B"}));
+            run(&mut s, "solid.box", &json!({"corner": [15, 10, 10], "length": 10, "width": 10, "height": 5, "operation": "join"}));
+            s
+        };
+        let turned = |turn: Option<&str>| {
+            let mut s = boss();
+            let mut p = json!({"edges": BASE, "radius": 1});
+            if let Some(t) = turn {
+                p["turn"] = json!(t);
+            }
+            let reply = run(&mut s, "solid.fillet", &p);
+            assert_eq!(reply["warning"], json!(null), "{reply}");
+            let body = s.world_state().unwrap().body("B").unwrap().body.clone();
+            assert!(body.validity().is_empty(), "{:?}", body.validity());
+            (s, solidcraft_kernel::measure(&body).unwrap(), body)
+        };
+        let (mitred, mitre, _) = turned(None);
+        let (_, named, _) = turned(Some("mitre"));
+        let (swept_session, swept, body) = turned(Some("swept"));
+        eprintln!("mitre: {} faces, {:.9}; swept: {} faces, {:.9}", mitre.faces, mitre.volume, swept.faces, swept.volume);
+        let r: f64 = 1.0;
+        let (a, m) = ((1.0 - PI / 4.0) * r * r, (5.0 / 6.0 - PI / 4.0) * r * r * r);
+        let near = |v: f64, want: f64| (v - want).abs() < 1e-9 * want;
+        assert!(near(mitre.volume, 12500.0 + 40.0 * a + 8.0 * m), "{}", mitre.volume);
+        assert!(near(swept.volume, 12500.0 + 40.0 * a + 2.0 * PI * m), "{}", swept.volume);
+        assert_eq!(named.volume.to_bits(), mitre.volume.to_bits(), "mitre is the default");
+        assert_eq!((mitre.faces, swept.faces), (15, 19));
+        // The four corner faces (the record's torus is a ring torus, so a horn torus is its exact
+        // rational form): every point on the horn torus about its upright edge.
+        let mut corners = 0;
+        for f in &body.record().faces {
+            if !matches!(f.surface, solidcore_record::brep::Surface::RationalSpline { .. }) {
+                continue;
+            }
+            corners += 1;
+            let eval = solidcraft_geom::brep::eval::SurfaceEval::new(&f.surface).unwrap();
+            let [[u0, u1], [v0, v1]] = f.domain;
+            for i in 0..=4 {
+                for j in 0..=4 {
+                    let p = eval.point([u0 + (u1 - u0) * f64::from(i) / 4.0, v0 + (v1 - v0) * f64::from(j) / 4.0]).unwrap();
+                    let (cx, cy) = (if p.x < 20.0 { 15.0 } else { 25.0 }, if p.y < 15.0 { 10.0 } else { 20.0 });
+                    let rho = (p.x - cx).hypot(p.y - cy);
+                    let off = ((rho - r).powi(2) + (p.z - 10.0 - r).powi(2)).sqrt() - r;
+                    assert!(off.abs() < 1e-9, "{p:?} is {off} off the horn torus");
+                }
+            }
+        }
+        assert_eq!(corners, 4);
+        assert!(!mitred.doc.to_json().contains("\"turn\""));
+        assert!(swept_session.doc.to_json().contains("\"turn\": \"swept\""));
+        let mut s = boss();
+        let e = s.execute("solid.fillet", &json!({"edges": BASE, "radius": 1, "turn": "round"})).unwrap_err().to_string();
+        assert!(e.contains("unknown turn `round` (mitre or swept)"), "{e}");
+        let e = s.execute("solid.fillet", &json!({"edges": BASE, "radius": 1, "turn": "swept", "type": "chord"})).unwrap_err().to_string();
+        assert!(e.contains(solidcraft_doc::SWEPT_TAKES), "{e}");
+        // A pocket 5 deep in the plate, its floor's edges rounded: the rounds meet at its concave
+        // upright edges.
+        let mut s = Session::default();
+        run(&mut s, "solid.box", &json!({"length": 40, "width": 30, "height": 10, "body_name": "P"}));
+        run(&mut s, "solid.box", &json!({"corner": [10, 10, 5], "length": 20, "width": 10, "height": 6, "operation": "cut"}));
+        let rim = json!([[20, 10, 5], [30, 15, 5], [20, 20, 5], [10, 15, 5]]);
+        let e = s.execute("solid.fillet", &json!({"edges": rim, "radius": 1, "turn": "swept"})).unwrap_err().to_string();
+        eprintln!("swept along a pocket's rim: {e}");
+        assert!(e.contains("swept corner at (") && e.contains("round that edge at a radius of at least 1 first"), "{e}");
+    }
 }
 #[cfg(test)]
 #[path = "fillet_connected_rounds_tests.rs"]

crates/engine/src/cmd/joints_coupling_tests.rs

@@ -408,3 +408,24 @@ fn a_motion_link_takes_its_driven_joints_freedom_with_nothing_grounded() {
         }
     }
 }
+
+/// Rolling the marker back works a gear's ratio out from the faces as they were then, so the
+/// editor's pinned model and its source differ in the link's ratio, and the edit still goes
+/// through.
+#[test]
+fn an_editor_accepts_the_ratios_rolling_the_marker_works_out() {
+    let mut s = gear_train();
+    let before = s.doc.features.len();
+    // G1's wall moves out to a radius of 12, so the link's ratio goes from -0.5 to -0.6.
+    run(&mut s, "solid.offset_face", json!({"faces": [[10, 0, 2.5]], "distance": 2}));
+    let ratio = |s: &Session| s.doc.assembly.links.first().map(|l| l.ratio).unwrap_or(f64::NAN);
+    assert!(close_to(ratio(&s), -0.6), "{}", ratio(&s));
+    let original = s.scratch();
+    run(&mut s, "timeline.roll_to", json!({"position": before}));
+    let source = s.scratch();
+    assert!(close_to(ratio(&source), -0.5), "before the offset, the pitch radius is 10: {}", ratio(&source));
+    let prepared = s.scratch().compute_editor_commands(&[], &source, original).unwrap();
+    s.accept_commands(prepared).unwrap();
+    assert_eq!(s.doc.marker, None);
+    assert!(close_to(ratio(&s), -0.6), "{}", ratio(&s));
+}

crates/engine/src/cmd/material_properties.rs

@@ -1,15 +1,24 @@
 //! Read-only validation of candidate engineering data; no assignment or simulation.
 use super::CommandSpec;
 use crate::params::bad;
+use crate::schema::material_properties::{CardModulus, CardValidated, DirectionalModulusParams, ValidateCardParams};
+use crate::schema::{TypedContract, output_schema_for};
 use crate::{Result, Session};
-use serde_json::{Value, json};
+use serde_json::Value;
 
-pub static COMMANDS: &[CommandSpec] = &[CommandSpec::new("material.properties.validate", "Validate Physical Material Data", validate)
+const VALIDATE_CONTRACT: TypedContract<ValidateCardParams> = TypedContract::new();
+const DIRECTIONAL_CONTRACT: TypedContract<DirectionalModulusParams> = TypedContract::new();
+
+pub static COMMANDS: &[CommandSpec] = &[CommandSpec::new("material.properties.validate", "Validate Physical Material Data", crate::checked!("material.properties.validate", validate))
     .icon("material")
     .noundo()
     .doc_only()
+    .contract(&VALIDATE_CONTRACT)
+    .output(output_schema_for::<CardValidated>)
     .params("card: schema_version 1 engineering material card in SI units. Returns numerical consistency, derived isotropic moduli, missing conditions and sources needing review. Read-only; does not assign/save properties or provide an analysis solver. See docs/physical-material-cards.md"),
-    CommandSpec::new("material.properties.directional", "Directional Elastic Modulus", directional).icon("material").noundo().doc_only()
+    CommandSpec::new("material.properties.directional", "Directional Elastic Modulus", crate::checked!("material.properties.directional", directional)).icon("material").noundo().doc_only()
+        .contract(&DIRECTIONAL_CONTRACT)
+        .output(output_schema_for::<CardModulus>)
         .params("card: schema_version 1 engineering material card; direction: three finite nonzero-vector components in the card's material-local axes. Returns normalized direction, Young modulus in Pa and source/condition review. Read-only constitutive query; no structural solver, persistence or body-axis assignment. See docs/physical-material-cards.md")];
 
 fn directional(_: &mut Session, params: &Value) -> Result<Value> {
@@ -28,7 +37,7 @@ fn directional(_: &mut Session, params: &Value) -> Result<Value> {
     let direction = [component(0)?, component(1)?, component(2)?];
     let card = solidcraft_doc::physical_material::admit_card(value).map_err(|e| bad(cmd, e.to_string()))?;
     let response = card.directional_modulus(direction).map_err(|e| bad(cmd, e.to_string()))?;
-    serde_json::to_value(response).map_err(|e| bad(cmd, e.to_string()))
+    serde_json::to_value(CardModulus::from(response)).map_err(|e| bad(cmd, e.to_string()))
 }
 
 fn validate(_: &mut Session, params: &Value) -> Result<Value> {
@@ -38,13 +47,15 @@ fn validate(_: &mut Session, params: &Value) -> Result<Value> {
         .ok_or_else(|| bad("material.properties.validate", "expected {card: ...}"))?;
     let card = object.get("card").ok_or_else(|| bad("material.properties.validate", "missing card"))?;
     let result = solidcraft_doc::physical_material::validate_card(card).map_err(|e| bad("material.properties.validate", e.to_string()))?;
-    Ok(json!({"valid":true,"validation":result}))
+    let reply = CardValidated { valid: true, validation: result.into(), param_warnings: Vec::new() };
+    serde_json::to_value(reply).map_err(|e| bad("material.properties.validate", e.to_string()))
 }
 
 #[cfg(test)]
 mod tests {
     use super::*;
     use crate::doc::Document;
+    use serde_json::json;
     use std::sync::Arc;
 
     fn card() -> Value {

crates/engine/src/cmd/plastic.rs

@@ -404,7 +404,7 @@ mod tests {
         s.run_script(&crate::sample::script()).unwrap();
         let lip = json!({"body": "Plate", "face": [51.89, 45.2, 8.0], "width": "1.5 mm", "height": "3.5 mm", "side": "inside", "type": "lip"});
         let e = s.execute("plastic.lip", &lip).unwrap_err().to_string();
-        assert!(e.contains("rim face") && e.contains("2 openings alike"), "{e}");
+        assert!(e.contains("one clear opening") && e.contains("2 openings alike"), "{e}");
         // The boss alone, no holes: its foot is not an opening either.
         let mut b = Session::default();
         run(&mut b, "solid.box", json!({"length": 80, "width": 50, "height": 8, "body_name": "Plate"}));

crates/engine/src/cmd/sheet_face_names_tests.rs

@@ -98,8 +98,53 @@ fn a_trays_faces_have_readable_sheet_names_that_follow_its_size() {
     assert_eq!(again, names);
     let right = point(&s, &format!("sheet:Body1:F{sd}.1:top"));
     assert!((right.x - 399.0).abs() < 1e-3, "{right:?}");
-    let far = point(&s, &format!("sheet:Body1:F{fb}.1:rim.far"));
-    assert!((199.0 - 1e-3..=200.0 + 1e-3).contains(&far.y) && (0.0..=400.0).contains(&far.x) && (far.z - 30.0).abs() < 1e-3, "{far:?}");
+    let rim = format!("sheet:Body1:F{fb}.1:rim.far");
+    let far = point(&s, &rim);
+    let st = s.model.state();
+    let hit = solidcraft_doc::naming::locate_one(&st, None, &rim).unwrap();
+    on_planar_face(&st.bodies[hit.body].body, hit.face, far);
+    assert!((far.z - 30.0).abs() < 1e-9 && (199.0..=200.0).contains(&far.y), "the back flange's far rim: {far:?}");
+}
+
+/// `p` lies on face `face` of `body`, on its exact geometry: within rounding at the part's scale
+/// of the plane the face lies on, and inside the boundary its edges trace there (each a line,
+/// counted by crossings).
+fn on_planar_face(body: &solidcraft_kernel::Body, face: usize, p: Vec3) {
+    use solidcore_record::brep::{Curve, Loop};
+    let rounding = 1e-12 * body.size().max(1.0);
+    let surface = solidcraft_kernel::face_surface(body, face).unwrap();
+    let on = surface.nearest(p).unwrap();
+    assert!(on.dist(p) <= rounding, "{p:?} is {} off face {face}'s surface", on.dist(p));
+    let solidcraft_kernel::FaceSurface::Plane { normal, .. } = surface else { panic!("face {face} is not planar: {surface:?}") };
+    // Coordinates in the plane: along `x` and `y`, square to its normal.
+    let x = if normal.cross(Vec3::X).len() > 0.5 { normal.cross(Vec3::X).normalized().unwrap() } else { normal.cross(Vec3::Y).normalized().unwrap() };
+    let y = normal.cross(x);
+    let local = |q: Vec3| ((q - p).dot(x), (q - p).dot(y));
+    let record = body.record();
+    let point = |v: u32| {
+        let q = record.vertices[v as usize].point;
+        Vec3::new(q[0], q[1], q[2])
+    };
+    // Crossings of the ray from `p` along +x with the face's boundary.
+    let mut crossings = 0;
+    for l in &record.faces[face].loops {
+        let Loop::Edges { edges } = l else { continue };
+        for e in edges {
+            let edge = &record.edges[e.edge as usize];
+            assert!(matches!(edge.parameters(), Curve::Line { .. }), "an edge of face {face} is not a line: {:?}", edge.parameters());
+            let [a, b] = edge.vertices.map(|v| local(point(v)));
+            let distance = {
+                let (dx, dy) = (b.0 - a.0, b.1 - a.1);
+                let t = (-(a.0 * dx + a.1 * dy) / (dx * dx + dy * dy)).clamp(0.0, 1.0);
+                (a.0 + t * dx).hypot(a.1 + t * dy)
+            };
+            assert!(distance > rounding, "{p:?} is on the boundary of face {face}");
+            if (a.1 > 0.0) != (b.1 > 0.0) && a.0 + (b.0 - a.0) * (0.0 - a.1) / (b.1 - a.1) > 0.0 {
+                crossings += 1;
+            }
+        }
+    }
+    assert_eq!(crossings % 2, 1, "{p:?} is outside face {face}'s boundary");
 }
 
 #[test]

crates/engine/src/cmd/surface_match.rs

@@ -10,12 +10,19 @@ use solidcraft_kernel::{Construction, Continuity};
 use super::CommandSpec;
 use super::features::add_feature;
 use crate::params::{bad, str_, vec3};
+use crate::schema::features::FeatureResult;
+use crate::schema::surface_match::MatchSurfaceParams;
+use crate::schema::{TypedContract, output_schema_for};
 use crate::{Result, Session};
 
+const CONTRACT: TypedContract<MatchSurfaceParams> = TypedContract::new();
+
 pub static COMMANDS: &[CommandSpec] = &[
-    CommandSpec::new("surface.match", "Match Surface", match_surface)
+    CommandSpec::new("surface.match", "Match Surface", crate::checked!("surface.match", match_surface))
         .at("SURFACE", "MODIFY")
         .icon("continuity")
+        .contract(&CONTRACT)
+        .output(output_schema_for::<FeatureResult>)
         .params(
             "body: surface name (the body whose face is rebuilt); faces?: [[x,y,z]] (points on that face, default: the body's first); target: body name (the body the seam must meet); edges: [[x,y,z]] (points on one edge chain of the target: the rebuilt boundary takes its place); order?: g1|g2|g3 (default g2: position and tangent plane, the curvature too, or how that curvature changes along the seam). The far boundary stays where it was and the body keeps its name",
         ),

crates/engine/src/computed_commands_tests.rs

@@ -280,3 +280,41 @@ fn cancelling_an_editor_with_visibility_changes_restores_an_existing_history_mar
     assert_eq!(session.doc.marker, Some(1));
     assert!(session.visibility.hidden_origin.is_empty());
 }
+
+/// Rolling the marker back before a move of the body a joint seats on solves the joints again,
+/// which puts the seated occurrence back where the body was: the editor's pinned model differs
+/// from its source there, and only there, and the edit still goes through.
+#[test]
+fn an_editor_accepts_the_placements_rolling_the_marker_solves() {
+    let mut session = Session::default();
+    for (name, x) in [("A", 0), ("B", 20)] {
+        session.execute("component.activate", &json!({"component": "root"})).unwrap();
+        session.execute("component.create", &json!({"name": name})).unwrap();
+        session.execute("solid.box", &json!({"length": 10, "width": 10, "height": 10, "corner": [x, 0, 0]})).unwrap();
+    }
+    let component = |s: &Session, name: &str| s.doc.components.iter().find(|c| c.name == name).map(|c| c.id).unwrap();
+    let occurrence = |s: &Session, name: &str| {
+        let component = component(s, name);
+        s.doc.occurrences.iter().find(|o| o.component == component).cloned().unwrap()
+    };
+    session.execute("occurrence.ground", &json!({"occurrence": occurrence(&session, "A").id, "grounded": true})).unwrap();
+    session
+        .execute("joint.create", &json!({"type": "rigid", "a": {"face": [5, 5, 10]}, "b": {"face": [25, 5, 0]}, "offset": 5, "name": "Seat"}))
+        .unwrap();
+    let seated = occurrence(&session, "B").transform;
+    // A's box moves along, and B, seated on it, with it.
+    session.execute("component.activate", &json!({"component": "A"})).unwrap();
+    let a = component(&session, "A");
+    let body = session.model.state().bodies.iter().find(|b| b.component == a).map(|b| b.name.clone()).unwrap();
+    session.execute("solid.move", &json!({"bodies": [body], "translate": [30, 0, 0]})).unwrap();
+    let moved = occurrence(&session, "B").transform;
+    assert_ne!(moved, seated, "B follows the box it is seated on");
+    let original = session.scratch();
+    session.execute("timeline.roll_to", &json!({"position": 2})).unwrap();
+    let source = session.scratch();
+    assert_eq!(occurrence(&session, "B").transform, seated, "before the move, B sits where the box was");
+    let prepared = session.scratch().compute_editor_commands(&[], &source, original).unwrap();
+    session.accept_commands(prepared).unwrap();
+    assert_eq!(session.doc.marker, None);
+    assert_eq!(occurrence(&session, "B").transform, moved);
+}

crates/engine/src/lib.rs

@@ -349,20 +349,16 @@ impl Ahead {
     /// [`Ahead::evaluate`], setting `step` to the number of the command running (from 1), so a
     /// front end can say how far a batch has got.
     pub fn evaluate_counting(self, commands: &[(String, Value)], step: &std::sync::atomic::AtomicUsize) -> Result<Evaluated> {
-        let stop = self.0.stop.clone();
-        stop.within(|| {
-            let (after, _) = self.0.preview_in_place(commands, Some(step))?;
-            after.world_state()?.warm_display();
-            Ok(Evaluated(after.model))
-        })
+        let (after, _) = self.0.preview_in_place(commands, Some(step))?;
+        after.world_state()?.warm_display();
+        Ok(Evaluated(after.model))
     }
 
     /// Run `commands` one after another, each reply or error in turn (what they evaluate stays
     /// in the shared evaluation cache): the checks a front end makes before a command, such as
     /// what a delete takes with it (#2678), computed off its window thread.
     pub fn replies(mut self, commands: &[(String, Value)]) -> Vec<Result<Value>> {
-        let stop = self.0.stop.clone();
-        stop.within(|| commands.iter().map(|(id, params)| self.0.execute(id, params)).collect())
+        commands.iter().map(|(id, params)| self.0.execute(id, params)).collect()
     }
 }
 
@@ -538,10 +534,6 @@ pub struct Session {
     /// not a move of the design's, so the placements the design reports and Capture Position
     /// keeps leave it out ([`Session::uncaptured_moves`]).
     pub exploded: std::collections::BTreeMap<u64, solidcraft_doc::Mat>,
-    /// Stops the work computing off the window thread for this design, shared with its copies.
-    stop: solidcraft_kernel::Stop,
-    /// A copy of a design ([`Session::scratch`]), sharing its token.
-    is_copy: bool,
     world_cache: std::sync::Mutex<Option<WorldCache>>,
     /// The design the joints were last solved for, as the solve left it, and the model it read
     /// (see [`Session::solve_joints`]).
@@ -802,8 +794,6 @@ impl Session {
     /// A session on `doc` evaluated as `model`, with what it hides.
     pub(crate) fn with_model(doc: Arc<Document>, visibility: Visibility, model: Model) -> Self {
         Session {
-            stop: Default::default(),
-            is_copy: false,
             saved: doc.clone(),
             doc,
             model,
@@ -884,11 +874,6 @@ impl Session {
     /// design before the batch, which is what the batch promised (#3242). The design is what a
     /// checkpoint keeps, not the replaced session's file path (docs/mcp.md).
     pub fn replace_design(&mut self, fresh: Session) {
-        // Nothing still computing for the design that leaves has anywhere to go. A copy leaves
-        // the design it came from going, and its token with it.
-        if !self.is_copy {
-            self.stop_computing();
-        }
         let auto_project = self.auto_project;
         let validation = self.validation();
         let single_surface_analysis = self.single_surface_analysis;
@@ -920,19 +905,6 @@ impl Session {
         self.replacements = replacements;
     }
 
-    /// The token over the work running off the window thread for this design, on any of its
-    /// copies: a job started from a copy runs [`solidcraft_kernel::Stop::within`] it.
-    pub fn stop_token(&self) -> solidcraft_kernel::Stop {
-        self.stop.clone()
-    }
-
-    /// This design is going away: the work still computing for it stops at the kernel's next
-    /// check, and its results go nowhere (they are only ever for this design's evaluation cache).
-    /// A kernel call that doesn't check runs to its end, on a kernel of its own, holding up nothing.
-    pub fn stop_computing(&self) {
-        self.stop.stop();
-    }
-
     /// Install (or with `None` remove) the check [`Session::execute`] runs before every command,
     /// for an app that embeds the engine and decides which commands may run. A refusal comes back
     /// as [`EngineError::Refused`] and leaves the session as it was.
@@ -1899,8 +1871,6 @@ impl Session {
     /// commands on without touching this one.
     pub fn scratch(&self) -> Session {
         Session {
-            stop: self.stop.clone(),
-            is_copy: true,
             doc: self.doc.clone(),
             model: self.model.clone(),
             undo: Vec::new(),
@@ -1991,6 +1961,23 @@ impl Session {
         }
         let mut expected = (*original.doc).clone();
         expected.marker = source.doc.marker;
+        // Rolling the marker solves the joints again and stores where that puts each occurrence.
+        if expected.occurrences.len() == source.doc.occurrences.len() {
+            for (e, s) in expected.occurrences.iter_mut().zip(&source.doc.occurrences) {
+                if e.id == s.id {
+                    e.transform = s.transform;
+                }
+            }
+        }
+        // ...and works out each coupled joint's ratio and lift from the faces at that marker.
+        if expected.assembly.links.len() == source.doc.assembly.links.len() {
+            for (e, s) in expected.assembly.links.iter_mut().zip(&source.doc.assembly.links) {
+                if (e.a, e.ia, e.b, e.ib) == (s.a, s.ia, s.b, s.ib) {
+                    e.ratio = s.ratio;
+                    e.lift = s.lift.clone();
+                }
+            }
+        }
         if expected != *source.doc {
             return Err(EngineError::Other("the original editor model does not match its source design".into()));
         }
@@ -2002,16 +1989,6 @@ impl Session {
         commands: &[(String, Value)],
         marker: Option<Option<usize>>,
         original: Option<Session>,
-    ) -> Result<ComputedCommands> {
-        let stop = self.stop.clone();
-        stop.within(|| self.compute_commands_under(commands, marker, original))
-    }
-
-    fn compute_commands_under(
-        self,
-        commands: &[(String, Value)],
-        marker: Option<Option<usize>>,
-        original: Option<Session>,
     ) -> Result<ComputedCommands> {
         let editor_original = original.as_ref().map(|session| session.doc.clone());
         let mut computed = self.scratch();

crates/engine/src/measure_centre_tests.rs

@@ -517,6 +517,7 @@ fn open_surface_measurements_have_no_volume_properties() {
     assert_eq!(props["total"]["open_bodies_skipped"], 1);
     assert!(props["bodies"][0]["mass_g"].is_null());
     assert!(props["total"]["center_of_mass"].is_null());
+    assert!(s.execute("inspect.center_of_mass", &json!({"bodies": ["OpenTube"]})).is_err(), "an open surface has no centre of mass");
 }
 
 #[test]
@@ -545,6 +546,43 @@ fn volume_totals_skip_open_surfaces_and_keep_closed_box_properties() {
     for key in ["volume_mm3", "mass_g", "center_of_mass"] {
         assert_eq!(props_before["total"][key], props_after["total"][key]);
     }
+    let com = run(&mut s, "inspect.center_of_mass", json!({}));
+    assert_eq!(com["skipped"].as_array().map(Vec::len), Some(1), "{com}");
+    assert_eq!(com["bodies"].as_array().map(Vec::len), Some(1), "{com}");
+    assert!(close(&com["volume"], 6000.0, 1e-9), "{com}");
+    for (axis, expected) in [5.0, 10.0, 15.0].into_iter().enumerate() {
+        assert!(close(&com["center"][axis], expected, 1e-9), "{com}");
+    }
+}
+
+/// #6173: Center of Mass reports the volume and centre Measure does. It measured the display
+/// mesh, whose flat facets cut curved faces short: a sphere of radius 10 came out 0.13 % small.
+#[test]
+fn center_of_mass_reports_the_same_volume_and_centre_as_measure() {
+    let mut s = Session::default();
+    run(&mut s, "solid.sphere", json!({"radius": 10, "center": [0, 0, 0], "body_name": "Ball"}));
+    run(&mut s, "solid.cylinder", json!({"base": [50, 0, 0], "radius": 10, "height": 20, "body_name": "Cup"}));
+    run(&mut s, "solid.shell", json!({"faces": [[50, 0, 20]], "thickness": 2}));
+    let measured = run(&mut s, "inspect.measure", json!({}));
+    let com = run(&mut s, "inspect.center_of_mass", json!({}));
+    let entry = |list: &Value, key: &str, name: &str| -> Value {
+        list.as_array().and_then(|l| l.iter().find(|b| b[key] == name)).cloned().unwrap_or_else(|| panic!("{name} in {list}"))
+    };
+    for name in ["Ball", "Cup"] {
+        let (m, c) = (entry(&measured["bodies"], "name", name), entry(&com["bodies"], "body", name));
+        assert!(close(&c["volume"], m["volume_mm3"].as_f64().unwrap(), 1e-9), "{name}: {c} vs {m}");
+        for axis in 0..3 {
+            assert!(close(&c["center"][axis], m["center_of_mass"][axis].as_f64().unwrap(), 1e-9), "{name}: {c} vs {m}");
+        }
+    }
+    assert!(close(&com["volume"], measured["total"]["volume_mm3"].as_f64().unwrap(), 1e-6), "{com} vs {measured}");
+    assert_eq!(com["skipped"].as_array().map(Vec::len), Some(0), "{com}");
+    // Worked out by hand: the sphere is 4/3 pi r^3, the cup a cylinder less its 8 x 18 bore.
+    let ball = 4.0 / 3.0 * PI * 1000.0;
+    let cup = PI * (100.0 * 20.0 - 64.0 * 18.0);
+    let (b, c) = (entry(&com["bodies"], "body", "Ball"), entry(&com["bodies"], "body", "Cup"));
+    assert!(close(&b["volume"], ball, ball * 2e-4), "{b}: want {ball}");
+    assert!(close(&c["volume"], cup, cup * 2e-4), "{c}: want {cup}");
 }
 
 /// An ASCII STL of the tetrahedron (0,0,0), (10,0,0), (0,10,0), (0,0,10), outward facing; `open`

crates/engine/src/schema/clearance.rs

@@ -0,0 +1,197 @@
+//! Contract and result types for `inspect.clearance` in `cmd/clearance.rs` (#11051).
+
+use std::borrow::Cow;
+use std::collections::BTreeMap;
+
+use schemars::{JsonSchema, Schema, SchemaGenerator, json_schema};
+use serde::de::Error as _;
+use serde::{Deserialize, Deserializer, Serialize};
+use serde_json::Value;
+
+use super::check::whole;
+use super::types::StringList;
+use crate::params;
+
+/// Most neighbours a body's `nearest` list holds.
+pub const MAX_NEAREST: usize = 1000;
+/// Largest clearance (mm).
+pub const MAX_CLEARANCE: f64 = 1e6;
+
+/// Find the solid bodies that overlap, and those closer than `clearance`, in world placement.
+/// Distances are measured on the exact faces and edges; the meshes only rule pairs out. Mesh
+/// bodies aren't measured: each is listed in `unchecked`.
+#[derive(Debug, Deserialize, JsonSchema)]
+#[schemars(deny_unknown_fields)]
+pub struct ClearanceParams {
+    /// The bodies to check (default: every solid body but those in `against`).
+    #[serde(default)]
+    pub bodies: Option<StringList>,
+    /// Only pairs with one body in `bodies` and the other here.
+    #[serde(default)]
+    pub against: Option<StringList>,
+    /// Smaller overlaps count as contact, in mm³ (default 0.01).
+    #[serde(default, deserialize_with = "min_volume")]
+    #[schemars(schema_with = "min_volume_schema")]
+    pub min_volume: Option<f64>,
+    /// Report pairs closer than this, in mm: 0 to 1 000 000 (default 0).
+    #[serde(default, deserialize_with = "clearance")]
+    #[schemars(schema_with = "clearance_schema")]
+    pub clearance: Option<f64>,
+    /// A gap below this is contact, 0, in mm: 0 to 1 (default 1e-6).
+    #[serde(default, deserialize_with = "tolerance")]
+    #[schemars(schema_with = "tolerance_schema")]
+    pub tolerance: Option<f64>,
+    /// Each body of `bodies` gets its this many nearest others, 0 to 1000 (default 0); a
+    /// fraction is rounded down.
+    #[serde(default, deserialize_with = "nearest")]
+    #[schemars(schema_with = "nearest_schema")]
+    pub nearest: Option<f64>,
+    #[serde(default)]
+    pub skip_within: Option<SkipWithin>,
+}
+
+/// A number from 0 to `max`, read as the handler reads it (`params::num`: finite, under 1e9 in
+/// size), with its message; `null` is the default.
+macro_rules! up_to {
+    ($read:ident, $schema:ident, $key:literal, $max:expr) => {
+        fn $read<'de, D: Deserializer<'de>>(d: D) -> Result<Option<f64>, D::Error> {
+            match Value::deserialize(d)? {
+                Value::Null => Ok(None),
+                v => v
+                    .as_f64()
+                    .and_then(params::finite)
+                    .filter(|x| (0.0..=$max).contains(x))
+                    .map(Some)
+                    .ok_or_else(|| D::Error::custom(whole(format!("`{}` must be a number from 0 to {}", $key, $max)))),
+            }
+        }
+
+        fn $schema(_: &mut SchemaGenerator) -> Schema {
+            json_schema!({"type": ["number", "null"], "minimum": 0, "maximum": f64::min($max, 1e9), "exclusiveMaximum": 1e9})
+        }
+    };
+}
+
+up_to!(min_volume, min_volume_schema, "min_volume", f64::MAX);
+up_to!(clearance, clearance_schema, "clearance", MAX_CLEARANCE);
+up_to!(tolerance, tolerance_schema, "tolerance", 1.0);
+up_to!(nearest, nearest_schema, "nearest", MAX_NEAREST as f64);
+
+/// Pairs not to check: of bodies of one occurrence (`occurrence`), or inside one placed
+/// component, its subcomponents included (`component`). `null` checks every pair.
+#[derive(Clone, Copy, Debug, PartialEq, Eq)]
+pub enum SkipWithin {
+    Occurrence,
+    Component,
+}
+
+impl<'de> Deserialize<'de> for SkipWithin {
+    fn deserialize<D: Deserializer<'de>>(d: D) -> Result<Self, D::Error> {
+        match Value::deserialize(d)?.as_str() {
+            Some("occurrence") => Ok(SkipWithin::Occurrence),
+            Some("component") => Ok(SkipWithin::Component),
+            _ => Err(D::Error::custom(whole("`skip_within` must be \"occurrence\", \"component\" or null"))),
+        }
+    }
+}
+
+impl JsonSchema for SkipWithin {
+    fn schema_name() -> Cow<'static, str> {
+        "SkipWithin".into()
+    }
+    fn inline_schema() -> bool {
+        true
+    }
+    fn json_schema(_: &mut SchemaGenerator) -> Schema {
+        json_schema!({
+            "description": "Pairs not to check: of bodies of one occurrence (`occurrence`), or inside one placed component, its subcomponents included (`component`). null checks every pair.",
+            "enum": ["occurrence", "component", null]
+        })
+    }
+}
+
+/// What `inspect.clearance` returns.
+#[derive(Debug, Serialize, JsonSchema)]
+pub struct Clearance {
+    /// Pairs that share at least `min_volume`.
+    pub overlaps: Vec<Overlap>,
+    /// Pairs closer than `clearance`, nearest first; a pair in contact is at 0.
+    pub near: Vec<NearPair>,
+    /// With `nearest`: each body of `bodies`, with its nearest others.
+    pub nearest: BTreeMap<String, Vec<Neighbour>>,
+    /// Pairs whose overlap couldn't be worked out, and each mesh body, which isn't measured
+    /// (`b` is then `null`).
+    pub unchecked: Vec<Unchecked>,
+    /// How many solid bodies were checked.
+    pub bodies: usize,
+    pub pairs_checked: usize,
+    /// Of those, the pairs measured by an earlier call: neither body changed or moved since.
+    pub pairs_reused: usize,
+    /// Pairs ruled out by their boxes.
+    pub pairs_pruned: usize,
+    /// Whether there were more pairs than one call measures.
+    pub truncated: bool,
+    /// How long it took (ms).
+    pub ms: f64,
+    /// In the warn parameter-check mode: what the call's parameters got wrong.
+    #[serde(default, skip_serializing_if = "Vec::is_empty")]
+    pub param_warnings: Vec<String>,
+}
+
+/// Two bodies that overlap.
+#[derive(Debug, Serialize, JsonSchema)]
+pub struct Overlap {
+    pub a: String,
+    pub b: String,
+    /// The volume they share (mm³).
+    pub volume_mm3: f64,
+    /// The area of the shared volume's surface (mm²).
+    pub area_mm2: f64,
+    pub bbox: OverlapBounds,
+    pub center: [f64; 3],
+}
+
+/// A box, by its corners.
+#[derive(Debug, Serialize, JsonSchema)]
+pub struct OverlapBounds {
+    pub min: [f64; 3],
+    pub max: [f64; 3],
+}
+
+/// Two bodies closer than `clearance`.
+#[derive(Debug, Serialize, JsonSchema)]
+pub struct NearPair {
+    pub a: String,
+    pub b: String,
+    pub distance_mm: f64,
+    /// The nearest point on `a`.
+    pub from: [f64; 3],
+    /// The nearest point on `b`.
+    pub to: [f64; 3],
+    /// For a contact: the volume they share, below `min_volume` (mm³).
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub overlap_mm3: Option<f64>,
+    /// `false` when measured on the meshes; absent when measured on the exact faces and edges.
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub exact: Option<bool>,
+}
+
+/// One of a body's nearest others.
+#[derive(Debug, Serialize, JsonSchema)]
+pub struct Neighbour {
+    pub body: String,
+    pub distance_mm: f64,
+}
+
+/// A pair, or a mesh body, that wasn't measured.
+#[derive(Debug, Serialize, JsonSchema)]
+pub struct Unchecked {
+    pub a: String,
+    /// The other body; `null` for a mesh body.
+    pub b: Option<String>,
+    pub reason: String,
+}
+
+#[cfg(test)]
+#[path = "clearance_tests.rs"]
+mod tests;

crates/engine/src/schema/clearance_tests.rs

@@ -0,0 +1,62 @@
+use serde_json::{Value, json};
+
+use super::{Clearance, ClearanceParams};
+use crate::Session;
+use crate::schema::tests::{assert_keys, assert_strict_keeps_todays_errors, conforms};
+use crate::schema::{ParamCheck, input_schema_for, output_schema_for};
+
+fn run(s: &mut Session, id: &str, p: Value) -> Value {
+    s.execute(id, &p).unwrap_or_else(|e| panic!("{id} {p}: {e}"))
+}
+
+#[test]
+fn schemas_and_the_key_check_agree() {
+    assert_keys(input_schema_for::<ClearanceParams>(), &["against", "bodies", "clearance", "min_volume", "nearest", "skip_within", "tolerance"]);
+}
+
+/// The handler reads the numbers and `skip_within` before the bodies, so each of these fails
+/// the same way on a design with no bodies.
+#[test]
+fn strict_keeps_todays_errors() {
+    assert_strict_keeps_todays_errors(&[
+        ("inspect.clearance", json!({"min_volume": -1})),
+        ("inspect.clearance", json!({"min_volume": "x"})),
+        ("inspect.clearance", json!({"min_volume": 2e9})),
+        ("inspect.clearance", json!({"clearance": 2e6})),
+        ("inspect.clearance", json!({"tolerance": 2})),
+        ("inspect.clearance", json!({"nearest": 1001})),
+        ("inspect.clearance", json!({"skip_within": "x"})),
+        ("inspect.clearance", json!({"skip_within": 5})),
+        ("inspect.clearance", json!({"bodies": ["Nope"]})),
+        ("inspect.clearance", json!({"against": "Nope"})),
+    ]);
+}
+
+/// #11051: a clearance check replies as its output schema says, in Warn without warnings for
+/// good calls and with them for a misspelt key: two overlapping boxes and a third 2 mm away,
+/// checked with every key, and with `against` alone.
+#[test]
+fn a_clearance_check_replies_with_its_schema() {
+    let schema = output_schema_for::<Clearance>();
+    let matches = |r: &Value, warned: bool| {
+        let schema = schema.as_value();
+        assert!(conforms(schema, schema, r), "{r} doesn't match {schema}");
+        assert_eq!(r.get("param_warnings").is_some(), warned, "{r}");
+    };
+    let mut s = Session { param_check: ParamCheck::Warn, ..Session::default() };
+    run(&mut s, "solid.box", json!({"length": 10, "width": 10, "height": 10, "body_name": "A"}));
+    run(&mut s, "solid.box", json!({"length": 10, "width": 10, "height": 10, "corner": [5, 5, 5], "body_name": "B", "operation": "new"}));
+    run(&mut s, "solid.box", json!({"length": 10, "width": 10, "height": 10, "corner": [12, -20, 0], "body_name": "C", "operation": "new"}));
+    let r = run(&mut s, "inspect.clearance", json!({}));
+    matches(&r, false);
+    assert_eq!(r["overlaps"].as_array().map(Vec::len), Some(1), "{r}");
+    let r = run(
+        &mut s,
+        "inspect.clearance",
+        json!({"bodies": ["A", "B"], "against": "C", "min_volume": 0.01, "clearance": 30, "tolerance": 1e-6, "nearest": 2, "skip_within": "occurrence"}),
+    );
+    matches(&r, false);
+    assert!(r["near"].as_array().is_some_and(|n| !n.is_empty()) && r["nearest"]["A"].is_array(), "{r}");
+    matches(&run(&mut s, "inspect.clearance", json!({"against": ["A"], "skip_within": null})), false);
+    matches(&run(&mut s, "inspect.clearance", json!({"clearence": 3})), true);
+}

crates/engine/src/schema/features.rs

@@ -10,9 +10,10 @@ use serde::{Deserialize, Serialize};
 use serde_json::Value;
 
 use super::types::{
-    AngleExpr, AxisDir, AxisLine, ConventionParam, DirectionParam, ExtentKeyword, ExtrudeOperation, FacesParam, FeatureCommon, FromPoint,
-    GeoRefParam, IdOrName, LengthExpr, NumberExpr, OperationParam, PlaneCommon, PlaneOrFace, Point3, PointExpr3, ProfilesParam, ScaleFactors,
-    SketchRef, StringList, ThinSideParam, ToPoint, TouchingParam, feature_common, present,
+    AngleExpr, AxisDir, AxisLine, ConventionParam, DirectionParam, EdgeRefs, ExtentKeyword, ExtrudeOperation, FacesParam, FeatureCommon,
+    FilletCornerParam, FilletFitParam, FilletTurnParam, FilletTypeParam, FromPoint, GeoRefParam, IdOrName, LengthExpr, NumberExpr, OperationParam,
+    PlaneCommon, PlaneOrFace, Point3, PointExpr3, ProfilesParam, ScaleFactors, SketchRef, StringList, ThinSideParam, ToPoint, TouchingParam,
+    feature_common, present,
 };
 
 /// Add a box primitive.
@@ -432,6 +433,92 @@ pub struct PlaneAtAngleParams {
     pub common: PlaneCommon,
 }
 
+/// Round edges of a body: a constant radius by default, or a chord, a curvature-continuous
+/// section or a radius varying along each edge (`type`).
+#[derive(Debug, Deserialize, JsonSchema)]
+#[schemars(deny_unknown_fields)]
+pub struct FilletParams {
+    /// The edges to round: a point on each, or `{body, index}`.
+    pub edges: EdgeRefs,
+    /// The radius; the chord's width with `type: chord`, the equivalent circular setback with
+    /// `type: curvature`, the start radius with `type: variable` or `spline`.
+    pub radius: LengthExpr,
+    /// The body whose edges the points pick. Default: whichever body has an edge there.
+    #[serde(default)]
+    pub body: Option<String>,
+    /// Round each picked edge's tangent chain with it. Default: true; false rounds exactly the
+    /// picked edges.
+    #[serde(default)]
+    pub tangent_chain: Option<bool>,
+    #[serde(default, rename = "type")]
+    pub kind: Option<FilletTypeParam>,
+    /// `type: variable`: the radius at the end away from `start`; it or `radius` may be 0, where
+    /// the round closes to the corner.
+    #[serde(default)]
+    pub radius2: Option<LengthExpr>,
+    /// `type: variable` or `spline`: a point near the end the radius starts from.
+    #[serde(default)]
+    pub start: Option<Point3>,
+    /// `type: variable`: radii between the ends, each `[position, radius]`, the position between 0
+    /// and 1 from the start end. At most 100 are read.
+    #[serde(default)]
+    pub mid: Option<Vec<(f64, LengthExpr)>>,
+    /// `type: variable`: smooth instead of straight between the radii. Default: false.
+    #[serde(default)]
+    pub smooth: Option<bool>,
+    /// `type: spline`: the control radii after `radius`. At most 100 are read.
+    #[serde(default)]
+    pub radii: Option<Vec<LengthExpr>>,
+    /// `type: spline`: the knot vector from 0 to 1, as many knots as all control radii, the
+    /// degree (1 to 3) and one more.
+    #[serde(default)]
+    pub knots: Option<Vec<f64>>,
+    #[serde(default)]
+    pub fit: Option<FilletFitParam>,
+    #[serde(default)]
+    pub corner: Option<FilletCornerParam>,
+    /// Corner setbacks: the corner at the vertex nearest each `vertex`, where every edge meeting it
+    /// is rounded, starts its patch `distance` along each of those edges from the vertex, past
+    /// where the rounds would meet. Constant-radius exact fillets only.
+    #[serde(default)]
+    pub setbacks: Option<Vec<SetbackParam>>,
+    #[serde(default)]
+    pub turn: Option<FilletTurnParam>,
+    #[serde(flatten, deserialize_with = "feature_common")]
+    pub common: FeatureCommon,
+}
+
+/// A fillet corner set back.
+#[derive(Debug, Deserialize, JsonSchema)]
+pub struct SetbackParam {
+    /// A point at the corner's vertex.
+    pub vertex: Point3,
+    /// How far along each edge there the corner's patch starts.
+    pub distance: LengthExpr,
+}
+
+/// The radius `fit: reduce` gave one edge.
+#[derive(Debug, Serialize, JsonSchema)]
+pub struct AppliedRadius {
+    /// A point on the edge.
+    pub edge: [f64; 3],
+    /// The radius it was rounded at.
+    pub radius: f64,
+}
+
+/// What `solid.fillet` returns: a feature command's reply, with the radii `fit: reduce` used.
+#[derive(Debug, Serialize, JsonSchema)]
+pub struct FilletResult {
+    #[serde(flatten)]
+    pub feature: FeatureResult,
+    /// With `fit: reduce` where it reduced the radius: the smallest radius used.
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub radius_applied: Option<f64>,
+    /// With `fit: reduce` where it reduced the radius: each edge's radius.
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub radii_applied: Option<Vec<AppliedRadius>>,
+}
+
 /// What a feature command returns.
 #[derive(Debug, Serialize, JsonSchema)]
 pub struct FeatureResult {

crates/engine/src/schema/features_tests.rs

@@ -1,8 +1,8 @@
 use serde_json::{Value, json};
 
 use super::{
-    BoundingSolidParams, BoxParams, ConeParams, CylinderParams, ExtrudeParams, FeatureResult, OffsetPlaneParams, PipeParams, PlaneAtAngleParams,
-    ScaleParams, SphereParams, TorusParams,
+    BoundingSolidParams, BoxParams, ConeParams, CylinderParams, ExtrudeParams, FeatureResult, FilletParams, FilletResult, OffsetPlaneParams,
+    PipeParams, PlaneAtAngleParams, ScaleParams, SphereParams, TorusParams,
 };
 use crate::Session;
 use crate::schema::tests::{assert_keys, assert_strict_keeps_todays_errors, conforms, sketch_rectangle};
@@ -87,6 +87,30 @@ fn schemas_and_the_key_check_agree() {
     assert_keys(input_schema_for::<ScaleParams>(), &["bodies", "factor", "factors", "name", "origin", "participants"]);
     assert_keys(input_schema_for::<OffsetPlaneParams>(), &["base", "name", "offset", "participants", "through"]);
     assert_keys(input_schema_for::<PlaneAtAngleParams>(), &["angle", "axis", "base", "name", "participants"]);
+    assert_keys(
+        input_schema_for::<FilletParams>(),
+        &[
+            "body",
+            "body_name",
+            "body_names",
+            "corner",
+            "edges",
+            "fit",
+            "knots",
+            "mid",
+            "name",
+            "participants",
+            "radii",
+            "radius",
+            "radius2",
+            "setbacks",
+            "smooth",
+            "start",
+            "tangent_chain",
+            "turn",
+            "type",
+        ],
+    );
 }
 
 #[test]
@@ -157,6 +181,13 @@ fn strict_keeps_todays_errors() {
         ("construct.plane.at_angle", json!({"base": "XY", "axis": {"face": "x", "point": [0, 0, 0]}, "angle": 30})),
         ("construct.plane.at_angle", json!({"base": "XY", "axis": {"face": "x"}, "angle": 30})),
         ("construct.plane.at_angle", json!({"base": "XY", "axis": "X", "angle": true})),
+        ("solid.fillet", json!({"edges": [[0, 0, 0]], "radius": 1, "turn": "round"})),
+        ("solid.fillet", json!({"edges": [[0, 0, 0]], "radius": 1, "turn": "ROUND"})),
+        ("solid.fillet", json!({"edges": [[0, 0, 0]], "radius": 1, "type": "bogus"})),
+        ("solid.fillet", json!({"edges": [[0, 0, 0]], "radius": 1, "fit": "bogus"})),
+        ("solid.fillet", json!({"edges": [[0, 0, 0]], "radius": 1, "corner": "round"})),
+        ("solid.fillet", json!({"edges": [], "radius": 1})),
+        ("solid.fillet", json!({"edges": 5, "radius": 1})),
     ]);
 }
 
@@ -213,6 +244,47 @@ fn replies_match_the_output_schema() {
     assert!(!conforms(schema, schema, &bad), "{bad}");
 }
 
+/// `solid.fillet` replies with `FilletResult` in each of its forms, its contract taking each: a
+/// boss's base rounded with each turn and its options spelled out, a reduced round (with the radii
+/// it used), chord and curvature rounds, a smooth-patch corner with setbacks, and the variable and
+/// spline forms.
+#[test]
+fn fillet_replies_match_its_output_schema() {
+    let schema = output_schema_for::<FilletResult>();
+    let schema = schema.as_value();
+    // A 40 x 30 x 10 plate with a 10 x 10 x 5 boss on it, whose base edges `boss` are.
+    let run = |p: Value| {
+        let mut s = Session { param_check: ParamCheck::Warn, ..Session::default() };
+        s.execute("solid.box", &json!({"length": 40, "width": 30, "height": 10, "body_name": "B"})).unwrap_or_else(|e| panic!("{e}"));
+        s.execute("solid.box", &json!({"corner": [15, 10, 10], "length": 10, "width": 10, "height": 5, "operation": "join"}))
+            .unwrap_or_else(|e| panic!("{e}"));
+        let r = s.execute("solid.fillet", &p).unwrap_or_else(|e| panic!("{p}: {e}"));
+        assert!(conforms(schema, schema, &r), "{r} doesn't match {schema}");
+        assert!(r.get("param_warnings").is_none(), "{p}: {r}");
+        r
+    };
+    let boss = json!([[20, 10, 10], [25, 15, 10], [20, 20, 10], [15, 15, 10]]);
+    run(
+        json!({"edges": boss, "radius": 1, "turn": "mitre", "type": "constant", "fit": "exact", "corner": "rolling", "tangent_chain": true, "body": "B", "name": "Round"}),
+    );
+    run(json!({"edges": boss, "radius": "1 mm", "turn": "Swept"}));
+    run(json!({"edges": boss, "radius": 1, "turn": "swept", "fit": "reduce"}));
+    let reduced = run(json!({"edges": [[20, 0, 10]], "radius": 15, "fit": "reduce"}));
+    assert!(reduced.get("radius_applied").is_some_and(Value::is_number) && reduced.get("radii_applied").is_some_and(Value::is_array), "{reduced}");
+    run(json!({"edges": [[20, 0, 10]], "radius": 1, "type": "chord"}));
+    run(json!({"edges": [{"body": "B", "index": 0}], "radius": 0.5, "tangent_chain": false}));
+    run(json!({"edges": [[20, 0, 10]], "radius": 1, "type": "curvature"}));
+    // Variable and spline radii: solidcore fails a variable round on a box edge at this pin (status
+    // 1001, as `variable_radius_on_a_box_edge`), so their forms are checked against the contract.
+    for p in [
+        json!({"edges": [[20, 0, 10]], "radius": 1, "type": "variable", "radius2": 2, "start": [0, 0, 10], "mid": [[0.5, "1.5 mm"]], "smooth": true}),
+        json!({"edges": [[20, 0, 10]], "radius": 1, "type": "spline", "start": [0, 0, 10], "radii": [2], "knots": [0, 0, 1, 1]}),
+    ] {
+        assert!(crate::schema::Contract::check(&crate::schema::TypedContract::<FilletParams>::new(), &p).is_empty(), "{p}");
+    }
+    run(json!({"edges": [[20, 0, 10], [40, 15, 10], [40, 0, 5]], "radius": 2, "corner": "g2", "setbacks": [{"vertex": [40, 0, 10], "distance": 4}]}));
+}
+
 /// The feature commands converted after box and extrude answer with `FeatureResult` too, and
 /// their contracts take every form these calls use: in Warn, a contract that refused one would
 /// still run the command, so the replies are checked for warnings too.

crates/engine/src/schema/material_properties.rs

@@ -0,0 +1,184 @@
+//! Contracts and result types for the commands in `cmd/material_properties.rs`: checking an
+//! engineering material card, and its elastic modulus in a direction (#11036).
+
+use std::borrow::Cow;
+use std::collections::BTreeMap;
+
+use schemars::{JsonSchema, Schema, SchemaGenerator, json_schema};
+use serde::de::Error as _;
+use serde::{Deserialize, Deserializer, Serialize};
+use serde_json::Value;
+use solidcraft_doc::physical_material::{DirectionalModulus, IsotropicModuli, MaterialAxes, Validation};
+
+use super::check::whole;
+
+/// Check an engineering material card: its numbers' consistency, the isotropic moduli they
+/// imply, and the conditions and sources still to review. Read-only: nothing is assigned or
+/// saved, and there is no analysis solver.
+#[derive(Debug, Deserialize, JsonSchema)]
+#[schemars(deny_unknown_fields)]
+pub struct ValidateCardParams {
+    #[schemars(schema_with = "card_schema")]
+    pub card: Value,
+}
+
+/// The Young modulus of an engineering material card in one direction, in the card's own
+/// material axes. Read-only: no load case or structural solver.
+#[derive(Debug, Deserialize, JsonSchema)]
+#[schemars(deny_unknown_fields)]
+pub struct DirectionalModulusParams {
+    #[schemars(schema_with = "card_schema")]
+    pub card: Value,
+    pub direction: CardDirection,
+}
+
+/// The card, checked by the handler (`admit_card`), with its messages.
+fn card_schema(_: &mut SchemaGenerator) -> Schema {
+    json_schema!({
+        "description": "A schema_version 1 engineering material card in SI units (see docs/physical-material-cards.md).",
+        "type": "object"
+    })
+}
+
+/// A direction in the card's material axes: three numbers, not all zero, with the handler's
+/// messages.
+#[derive(Clone, Copy, Debug, PartialEq)]
+pub struct CardDirection(pub [f64; 3]);
+
+impl<'de> Deserialize<'de> for CardDirection {
+    fn deserialize<D: Deserializer<'de>>(d: D) -> Result<Self, D::Error> {
+        let v = Value::deserialize(d)?;
+        let a =
+            v.as_array().filter(|a| a.len() == 3).ok_or_else(|| D::Error::custom(whole("direction: expected exactly three numeric components")))?;
+        let c = |i: usize| a.get(i).and_then(Value::as_f64).ok_or_else(|| D::Error::custom(whole("direction: expected numeric components")));
+        Ok(CardDirection([c(0)?, c(1)?, c(2)?]))
+    }
+}
+
+impl JsonSchema for CardDirection {
+    fn schema_name() -> Cow<'static, str> {
+        "CardDirection".into()
+    }
+    fn inline_schema() -> bool {
+        true
+    }
+    fn json_schema(_: &mut SchemaGenerator) -> Schema {
+        json_schema!({
+            "description": "A direction in the card's material axes: three numbers, not all zero.",
+            "type": "array",
+            "items": {"type": "number"},
+            "minItems": 3,
+            "maxItems": 3
+        })
+    }
+}
+
+/// What `material.properties.validate` returns.
+#[derive(Debug, Serialize, JsonSchema)]
+pub struct CardValidated {
+    /// Always true: a card that isn't valid is refused.
+    pub valid: bool,
+    pub validation: CardValidation,
+    /// In the warn parameter-check mode: what the call's parameters got wrong.
+    #[serde(default, skip_serializing_if = "Vec::is_empty")]
+    pub param_warnings: Vec<String>,
+}
+
+/// What `material.properties.directional` returns.
+#[derive(Debug, Serialize, JsonSchema)]
+pub struct CardModulus {
+    /// The direction, made a unit vector.
+    pub direction: [f64; 3],
+    /// The card's material axes, when it has directional properties.
+    pub axes: Option<CardAxes>,
+    /// The Young modulus in that direction (Pa).
+    pub young_modulus_pa: f64,
+    pub validation: CardValidation,
+    /// In the warn parameter-check mode: what the call's parameters got wrong.
+    #[serde(default, skip_serializing_if = "Vec::is_empty")]
+    pub param_warnings: Vec<String>,
+}
+
+impl From<DirectionalModulus> for CardModulus {
+    fn from(m: DirectionalModulus) -> Self {
+        let DirectionalModulus { direction, axes, young_modulus_pa, validation } = m;
+        CardModulus { direction, axes: axes.map(CardAxes::from), young_modulus_pa, validation: validation.into(), param_warnings: Vec::new() }
+    }
+}
+
+/// A card's material axes.
+#[derive(Clone, Copy, Debug, Serialize, JsonSchema)]
+#[serde(rename_all = "snake_case")]
+pub enum CardAxes {
+    /// The material's own axes 1, 2 and 3.
+    Material123,
+    /// Wood's longitudinal, radial and tangential axes.
+    WoodLrt,
+}
+
+impl From<MaterialAxes> for CardAxes {
+    fn from(a: MaterialAxes) -> Self {
+        match a {
+            MaterialAxes::Material123 => CardAxes::Material123,
+            MaterialAxes::WoodLrt => CardAxes::WoodLrt,
+        }
+    }
+}
+
+/// What checking a card found.
+#[derive(Debug, Serialize, JsonSchema)]
+pub struct CardValidation {
+    pub schema_version: u32,
+    /// The kinds of property the card gives.
+    pub property_kinds: Vec<String>,
+    /// The shear and bulk moduli an isotropic card's numbers imply.
+    pub isotropic_moduli: Option<CardModuli>,
+    /// The property kinds given without every condition they hold at (temperature, state, and
+    /// moisture for wood or strain rate for polymers).
+    pub unspecified_conditions: Vec<String>,
+    /// Per property kind: the condition fields it lacks.
+    pub missing_condition_fields: BTreeMap<String, Vec<String>>,
+    /// The sources the card's properties cite, which still need review.
+    pub source_review_required: Vec<String>,
+    /// Always false: there is no analysis solver.
+    pub analysis_solver_available: bool,
+    /// Always false: a card holds no rendering properties.
+    pub rendering_properties_available: bool,
+}
+
+impl From<Validation> for CardValidation {
+    fn from(v: Validation) -> Self {
+        // In full, so a field added to `Validation` fails here rather than going missing.
+        let Validation {
+            schema_version,
+            property_kinds,
+            isotropic_moduli,
+            unspecified_conditions,
+            missing_condition_fields,
+            source_review_required,
+            analysis_solver_available,
+            rendering_properties_available,
+        } = v;
+        CardValidation {
+            schema_version,
+            property_kinds,
+            isotropic_moduli: isotropic_moduli.map(|IsotropicModuli { shear_pa, bulk_pa }| CardModuli { shear_pa, bulk_pa }),
+            unspecified_conditions,
+            missing_condition_fields,
+            source_review_required,
+            analysis_solver_available,
+            rendering_properties_available,
+        }
+    }
+}
+
+/// The isotropic moduli a card's numbers imply.
+#[derive(Debug, Serialize, JsonSchema)]
+pub struct CardModuli {
+    pub shear_pa: f64,
+    pub bulk_pa: f64,
+}
+
+#[cfg(test)]
+#[path = "material_properties_tests.rs"]
+mod tests;

crates/engine/src/schema/material_properties_tests.rs

@@ -0,0 +1,58 @@
+use serde_json::{Value, json};
+
+use super::{CardModulus, CardValidated, DirectionalModulusParams, ValidateCardParams};
+use crate::Session;
+use crate::schema::tests::{assert_keys, assert_strict_keeps_todays_errors, conforms};
+use crate::schema::{ParamCheck, input_schema_for, output_schema_for};
+
+/// An isotropic card, as the command's own tests write one.
+fn card() -> Value {
+    json!({"schema_version":1,"designation":"Original synthetic card, not design data","family":"other",
+        "sources":[{"id":"fixture","title":"Original analytic constants","kind":"illustrative","license":"MIT OR Apache-2.0"}],
+        "properties":[{"source_id":"fixture","conditions":{"temperature_k":293.15,"state":"synthetic"},
+            "data":{"kind":"density","kg_m3":700.0}},
+            {"source_id":"fixture","data":{"kind":"elasticity","model":{
+                "symmetry":"isotropic","young_modulus_pa":12.25e9,"poisson_ratio":0.25}}}]})
+}
+
+#[test]
+fn schemas_and_the_key_check_agree() {
+    assert_keys(input_schema_for::<ValidateCardParams>(), &["card"]);
+    assert_keys(input_schema_for::<DirectionalModulusParams>(), &["card", "direction"]);
+}
+
+#[test]
+fn strict_keeps_todays_errors() {
+    assert_strict_keeps_todays_errors(&[
+        ("material.properties.validate", json!({"card": {}})),
+        ("material.properties.validate", json!({"card": null})),
+        ("material.properties.directional", json!({"card": {}, "direction": [1, 0, 0]})),
+        ("material.properties.directional", json!({"card": card(), "direction": [1, 0]})),
+        ("material.properties.directional", json!({"card": card(), "direction": "x"})),
+        ("material.properties.directional", json!({"card": card(), "direction": [1, "a", 0]})),
+        ("material.properties.directional", json!({"card": card(), "direction": [0, 0, 0]})),
+    ]);
+}
+
+/// #11036: both commands reply as their output schemas say, in Warn without warnings. Like the
+/// handlers, warn and strict refuse a key they don't take, so no reply carries a warning.
+#[test]
+fn card_commands_reply_with_their_schemas() {
+    let (validated, modulus) = (output_schema_for::<CardValidated>(), output_schema_for::<CardModulus>());
+    let matches = |schema: &schemars::Schema, r: &Value| {
+        let schema = schema.as_value();
+        assert!(conforms(schema, schema, r), "{r} doesn't match {schema}");
+        assert!(r.get("param_warnings").is_none(), "{r}");
+    };
+    let mut s = Session { param_check: ParamCheck::Warn, ..Session::default() };
+    let r = s.execute("material.properties.validate", &json!({"card": card()})).unwrap_or_else(|e| panic!("{e}"));
+    matches(&validated, &r);
+    assert!(r["valid"] == true && r["validation"]["isotropic_moduli"]["shear_pa"].is_number(), "{r}");
+    let r = s.execute("material.properties.directional", &json!({"card": card(), "direction": [1, 1, 0]})).unwrap_or_else(|e| panic!("{e}"));
+    matches(&modulus, &r);
+    assert!(r["axes"].is_null() && (r["young_modulus_pa"].as_f64().unwrap_or(0.0) - 12.25e9).abs() < 1.0, "{r}");
+    for level in [ParamCheck::Warn, ParamCheck::Strict] {
+        let mut s = Session { param_check: level, ..Session::default() };
+        assert!(s.execute("material.properties.validate", &json!({"card": card(), "crd": 1})).is_err(), "{level:?}");
+    }
+}

crates/engine/src/schema/mod.rs

@@ -57,6 +57,7 @@ mod tests;
 pub mod appearance;
 pub mod bom;
 pub mod browser;
+pub mod clearance;
 pub mod component;
 pub mod config;
 pub mod construct;
@@ -68,6 +69,7 @@ pub mod inspect;
 pub mod joints;
 pub mod libraries;
 pub mod mass_properties;
+pub mod material_properties;
 pub mod motion;
 pub mod panels;
 pub mod print_face;
@@ -84,6 +86,7 @@ pub mod sketch_equation;
 pub mod sketch_inspect;
 pub mod surface_analysis;
 pub mod surface_boundary;
+pub mod surface_match;
 pub mod ui_prefs;
 pub mod view_navigation;
 

crates/engine/src/schema/surface_match.rs

@@ -0,0 +1,165 @@
+//! Contract for `surface.match` in `cmd/surface_match.rs` (#10981). It returns `add_feature`'s
+//! reply, a [`super::features::FeatureResult`].
+
+use std::borrow::Cow;
+
+use schemars::{JsonSchema, Schema, SchemaGenerator, json_schema};
+use serde::de::Error as _;
+use serde::{Deserialize, Deserializer};
+use serde_json::Value;
+use solidcore_record::Vec3;
+use solidcraft_kernel::{Construction, Continuity};
+
+use super::check::whole;
+use super::types::{Point3, StringList, present};
+use crate::params;
+
+/// Rebuild one face of a surface body so that its boundary nearest a picked edge chain of another
+/// body lies on that chain and repeats that body's shape there up to `order`, while the opposite
+/// boundary keeps its place. The body keeps its name: a match changes it rather than making one.
+#[derive(Debug, Deserialize, JsonSchema)]
+#[schemars(deny_unknown_fields)]
+pub struct MatchSurfaceParams {
+    /// The surface body whose face is rebuilt, by name.
+    #[serde(deserialize_with = "body")]
+    pub body: String,
+    #[serde(default)]
+    pub faces: Option<MatchFaces>,
+    /// The body the seam must meet, by name.
+    #[serde(deserialize_with = "target")]
+    pub target: String,
+    pub edges: MatchEdges,
+    /// How closely the seam follows the target: `g1` (tangent), `g2` (curvature, the default) or
+    /// `g3`, in any case.
+    #[serde(default, deserialize_with = "present")]
+    #[schemars(with = "MatchOrder")]
+    pub order: Option<MatchOrder>,
+    // Not `FeatureCommon`: a match makes no body, so `body_name` and `body_names` would do
+    // nothing. `participants` stays because `timeline.redefine` passes a feature's own back.
+    /// The feature's name in the timeline.
+    #[serde(default)]
+    pub name: Option<String>,
+    /// The bodies taking part, which every feature records; each an existing body or `*`. A match
+    /// changes only `body`, whatever this lists.
+    #[serde(default)]
+    pub participants: Option<StringList>,
+}
+
+/// A body name, with the handler's message for anything that isn't text.
+fn body<'de, D: Deserializer<'de>>(d: D) -> Result<String, D::Error> {
+    match Value::deserialize(d)? {
+        Value::String(s) => Ok(s),
+        _ => Err(D::Error::custom(whole("`body` is required"))),
+    }
+}
+
+/// The target's name, with the handler's message for anything that isn't text.
+fn target<'de, D: Deserializer<'de>>(d: D) -> Result<String, D::Error> {
+    match Value::deserialize(d)? {
+        Value::String(s) => Ok(s),
+        _ => Err(D::Error::custom(whole("`target` is required"))),
+    }
+}
+
+/// Points `params::vec3` reads, or none if any isn't one.
+fn points(v: &[Value]) -> Option<Vec<Vec3>> {
+    v.iter().map(params::vec3).collect()
+}
+
+/// Points on the face to rebuild, at most 64 (default: the body's first face).
+#[derive(Clone, Debug, PartialEq)]
+pub struct MatchFaces(pub Vec<Vec3>);
+
+impl<'de> Deserialize<'de> for MatchFaces {
+    fn deserialize<D: Deserializer<'de>>(d: D) -> Result<Self, D::Error> {
+        let faces =
+            Value::deserialize(d)?.as_array().and_then(|a| points(a)).ok_or_else(|| D::Error::custom("must be a list of points [x, y, z]"))?;
+        if faces.len() > 64 {
+            return Err(D::Error::custom(whole("too many points on the face to rebuild")));
+        }
+        Ok(MatchFaces(faces))
+    }
+}
+
+impl JsonSchema for MatchFaces {
+    fn schema_name() -> Cow<'static, str> {
+        "MatchFaces".into()
+    }
+    fn inline_schema() -> bool {
+        true
+    }
+    fn json_schema(generator: &mut SchemaGenerator) -> Schema {
+        let point = generator.subschema_for::<Point3>();
+        json_schema!({
+            "description": "Points on the face to rebuild, at most 64 (default: the body's first face).",
+            "type": "array",
+            "items": point,
+            "maxItems": 64
+        })
+    }
+}
+
+/// Points on one edge chain of the target: the rebuilt boundary takes its place. 1 to 10 000,
+/// with the handler's message for anything else.
+#[derive(Clone, Debug, PartialEq)]
+pub struct MatchEdges(pub Vec<Vec3>);
+
+impl<'de> Deserialize<'de> for MatchEdges {
+    fn deserialize<D: Deserializer<'de>>(d: D) -> Result<Self, D::Error> {
+        Value::deserialize(d)?
+            .as_array()
+            .and_then(|a| points(a))
+            .filter(|edges| !edges.is_empty() && edges.len() <= 10_000)
+            .map(MatchEdges)
+            .ok_or_else(|| D::Error::custom(whole("`edges` must list 1 to 10000 points on the target's edge chain")))
+    }
+}
+
+impl JsonSchema for MatchEdges {
+    fn schema_name() -> Cow<'static, str> {
+        "MatchEdges".into()
+    }
+    fn inline_schema() -> bool {
+        true
+    }
+    fn json_schema(generator: &mut SchemaGenerator) -> Schema {
+        let point = generator.subschema_for::<Point3>();
+        json_schema!({
+            "description": "Points on one edge chain of the target: the rebuilt boundary takes its place.",
+            "type": "array",
+            "items": point,
+            "minItems": 1,
+            "maxItems": 10000
+        })
+    }
+}
+
+/// A match's continuity, as `params::continuity` reads it for a match (g1 to g3), with its messages.
+#[derive(Clone, Copy, Debug, PartialEq)]
+pub struct MatchOrder(pub Continuity);
+
+impl<'de> Deserialize<'de> for MatchOrder {
+    fn deserialize<D: Deserializer<'de>>(d: D) -> Result<Self, D::Error> {
+        let v = Value::deserialize(d)?;
+        params::continuity("surface.match", Some(&v), "`order`", Construction::Match).map(MatchOrder).map_err(|e| match e {
+            crate::EngineError::BadParams { msg, .. } => D::Error::custom(whole(msg)),
+            other => D::Error::custom(whole(other.to_string())),
+        })
+    }
+}
+
+impl JsonSchema for MatchOrder {
+    fn schema_name() -> Cow<'static, str> {
+        "MatchOrder".into()
+    }
+    fn inline_schema() -> bool {
+        true
+    }
+    fn json_schema(_: &mut SchemaGenerator) -> Schema {
+        json_schema!({"type": "string", "pattern": "^[gG][123]$"})
+    }
+}
+
+#[cfg(test)]
+#[path = "surface_match_tests.rs"]
+mod tests;

crates/engine/src/schema/surface_match_tests.rs

@@ -0,0 +1,121 @@
+use serde_json::{Value, json};
+use solidcore_record::Vec3;
+
+use super::MatchSurfaceParams;
+use crate::Session;
+use crate::schema::features::FeatureResult;
+use crate::schema::tests::{assert_keys, conforms};
+use crate::schema::{ParamCheck, input_schema_for, output_schema_for};
+
+fn run(s: &mut Session, id: &str, p: Value) -> Value {
+    s.execute(id, &p).unwrap_or_else(|e| panic!("{id} {p}: {e}"))
+}
+
+/// Two points on the cylinder's straight vertical wall seam, as the command's own tests pick it.
+fn picks(s: &Session) -> Vec<Vec3> {
+    let boss = s.world_state().ok().and_then(|st| st.body("Boss").map(|b| b.body.clone())).unwrap_or_else(|| panic!("no Boss"));
+    let e = boss
+        .edges(boss.size() * 1e-2)
+        .unwrap_or_default()
+        .into_iter()
+        .find(|e| e.length > 25.0 && (e.mid.x.hypot(e.mid.y) - 10.0).abs() < 0.05 && e.mid.z > 5.0 && e.mid.z < 25.0)
+        .unwrap_or_else(|| panic!("the cylinder has a straight vertical wall seam"));
+    let (a, b) = (e.points.first().copied().unwrap_or(e.mid), e.points.last().copied().unwrap_or(e.mid));
+    vec![a + (b - a) * 0.25, a + (b - a) * 0.75]
+}
+
+/// A cylinder `Boss` of radius 10, 30 high, and a cylindrical surface `Skirt` of radius 11 from
+/// the cylinder's wall seam round 60 degrees, as in the command's own tests: a point on the skirt.
+fn boss_and_skirt(s: &mut Session) -> [f64; 3] {
+    run(s, "sketch.create", json!({"plane": "XY", "name": "Round"}));
+    run(s, "sketch.circle.center", json!({"center": [0, 0], "radius": 10}));
+    run(s, "sketch.finish", json!({}));
+    run(s, "solid.extrude", json!({"sketch": "Round", "distance": 30, "body_name": "Boss"}));
+    let seam = picks(s)[0];
+    let a = seam.y.atan2(seam.x);
+    let at = |t: f64| json!([11.0 * t.cos(), 11.0 * t.sin()]);
+    run(s, "sketch.create", json!({"plane": "XY", "name": "Skirt sketch"}));
+    let arc = run(s, "sketch.arc.three_point", json!({"start": at(a), "end": at(a + 60f64.to_radians()), "through": at(a + 30f64.to_radians())}))
+        ["created"]["curves"][0]
+        .clone();
+    run(s, "sketch.finish", json!({}));
+    run(s, "surface.extrude", json!({"sketch": "Skirt sketch", "curves": [arc], "distance": 30, "body_name": "Skirt"}));
+    let mid = a + 30f64.to_radians();
+    [11.0 * mid.cos(), 11.0 * mid.sin(), 15.0]
+}
+
+#[test]
+fn schemas_and_the_key_check_agree() {
+    assert_keys(input_schema_for::<MatchSurfaceParams>(), &["body", "edges", "faces", "name", "order", "participants", "target"]);
+}
+
+/// A call that fails today gets the same message in strict. The handler looks both bodies up
+/// before it reads the picks, so each call runs on a design with two (a missing `edges` is left
+/// out: strict says it is required, the handler what it must list).
+#[test]
+fn strict_keeps_todays_errors() {
+    let many = vec![[0, 0, 0]; 10_001];
+    let faces = vec![[0, 0, 0]; 65];
+    let e = json!([[0, 0, 0]]);
+    for p in [
+        json!({"target": "T", "edges": e}),
+        json!({"body": 5, "target": "T", "edges": e}),
+        json!({"body": "Nope", "target": "T", "edges": e}),
+        json!({"body": "B", "edges": e}),
+        json!({"body": "B", "target": [], "edges": e}),
+        json!({"body": "B", "target": "Nope", "edges": e}),
+        json!({"body": "B", "target": "T", "faces": faces, "edges": e}),
+        json!({"body": "B", "target": "T", "edges": []}),
+        json!({"body": "B", "target": "T", "edges": null}),
+        json!({"body": "B", "target": "T", "edges": 5}),
+        json!({"body": "B", "target": "T", "edges": [[1, 2]]}),
+        json!({"body": "B", "target": "T", "edges": many}),
+        json!({"body": "B", "target": "T", "edges": e, "order": "g5"}),
+        json!({"body": "B", "target": "T", "edges": e, "order": "g0"}),
+        json!({"body": "B", "target": "T", "edges": e, "order": null}),
+        json!({"body": "B", "target": "T", "edges": e, "order": 2}),
+        json!({"body": "B", "target": "T", "edges": e}),
+    ] {
+        let error = |level: ParamCheck| {
+            let mut s = Session::default();
+            run(&mut s, "solid.box", json!({"length": 4, "width": 4, "height": 4, "body_name": "B"}));
+            run(&mut s, "solid.box", json!({"length": 4, "width": 4, "height": 4, "corner": [10, 0, 0], "body_name": "T"}));
+            s.param_check = level;
+            s.execute("surface.match", &p).err().map(|e| e.to_string())
+        };
+        let off = error(ParamCheck::Off);
+        assert!(off.is_some(), "{p} should fail today");
+        assert_eq!(error(ParamCheck::Strict), off, "{p}");
+    }
+}
+
+/// #10981: a match replies with `FeatureResult`, in Warn without warnings for good calls (the
+/// body's first face, and a picked face with every other key) and with them for a misspelt key;
+/// strict refuses a face point the handler would drop.
+#[test]
+fn a_match_replies_with_the_feature_result() {
+    let schema = output_schema_for::<FeatureResult>();
+    let matches = |r: &Value, warned: bool| {
+        let schema = schema.as_value();
+        assert!(conforms(schema, schema, r), "{r} doesn't match {schema}");
+        assert_eq!(r.get("param_warnings").is_some(), warned, "{r}");
+    };
+    let mut s = Session { param_check: ParamCheck::Warn, ..Session::default() };
+    let on_skirt = boss_and_skirt(&mut s);
+    let chain = picks(&s);
+    let r = run(&mut s, "surface.match", json!({"body": "Skirt", "target": "Boss", "edges": chain, "order": "G2"}));
+    matches(&r, false);
+    assert_eq!(r["changed_bodies"], json!(["Skirt"]), "{r}");
+    let r = run(
+        &mut s,
+        "surface.match",
+        json!({"body": "Skirt", "faces": [on_skirt], "target": "Boss", "edges": chain, "order": "g1", "name": "Seam", "participants": ["*"]}),
+    );
+    matches(&r, false);
+    assert_eq!(r["name"], "Seam", "{r}");
+    matches(&run(&mut s, "surface.match", json!({"body": "Skirt", "target": "Boss", "edges": chain, "ordr": "g3"})), true);
+    s.param_check = ParamCheck::Strict;
+    let error = s.execute("surface.match", &json!({"body": "Skirt", "faces": [on_skirt, [1, 2]], "target": "Boss", "edges": chain}));
+    let error = error.err().map(|e| e.to_string());
+    assert!(error.as_deref().is_some_and(|e| e.contains("`faces` must be a list of points")), "{error:?}");
+}

crates/engine/src/schema/tests.rs

@@ -367,7 +367,7 @@ fn issues_are_read_from_the_commands_own_contract() {
     assert_eq!(messages(&issues), ["unknown key `operaton`; did you mean `operation`?"]);
     assert_eq!(issues, box_contract().check(&json!({"length": 1, "width": 1, "height": 1, "operaton": "cut"})));
     // No contract, or no such command: nothing to say.
-    assert!(super::issues("solid.fillet", &json!({"nonsense": 1})).is_empty());
+    assert!(super::issues("solid.chamfer", &json!({"nonsense": 1})).is_empty());
     assert!(super::issues("no.such", &json!({"nonsense": 1})).is_empty());
 }
 

crates/engine/src/schema/types.rs

@@ -464,6 +464,66 @@ fn enum_schema(values: &[&str], description: &str) -> Schema {
     json_schema!({"description": description, "type": "string", "enum": values})
 }
 
+/// A keyword a handler reads with `str_` and lowercases, refusing any other word with `unknown
+/// <what> `<word>` (<expected>)`; the lowercased word is kept for the handler.
+macro_rules! keyword_param {
+    ($(#[$doc:meta])* $name:ident, $what:literal, $values:expr, $expected:literal, $description:literal) => {
+        $(#[$doc])*
+        #[derive(Clone, Debug, PartialEq)]
+        pub struct $name(pub String);
+
+        impl<'de> Deserialize<'de> for $name {
+            fn deserialize<D: Deserializer<'de>>(d: D) -> Result<Self, D::Error> {
+                let ok = |s: &str| $values.contains(&s.to_ascii_lowercase().as_str());
+                let unknown = |s: &str| whole(format!(concat!("unknown ", $what, " `{}` (", $expected, ")"), s.to_ascii_lowercase()));
+                string_matching(d, ok, $expected, unknown).map(|s| $name(s.to_ascii_lowercase()))
+            }
+        }
+
+        impl JsonSchema for $name {
+            fn schema_name() -> Cow<'static, str> {
+                stringify!($name).into()
+            }
+            fn json_schema(_: &mut SchemaGenerator) -> Schema {
+                enum_schema($values, $description)
+            }
+        }
+    };
+}
+
+keyword_param!(
+    /// `solid.fillet`'s `type`.
+    FilletTypeParam,
+    "fillet type",
+    &["constant", "rolling_ball", "chord", "chord_length", "curvature", "g2", "variable", "spline"],
+    "constant, chord, variable, spline or curvature",
+    "The round's section: constant (the default; rolling_ball is an alias), chord (`radius` is the width across; alias chord_length), curvature (alias g2: curvature-continuous between planar faces along straight edges, `radius` the equivalent circular setback), variable (`radius` at the end nearest `start`, `radius2` at the other) or spline (the radius a clamped B-spline from `start`: `radius`, then `radii`, over `knots`). Matching ignores case."
+);
+keyword_param!(
+    /// `solid.fillet`'s `fit`.
+    FilletFitParam,
+    "fit",
+    &["exact", "reduce", "taper"],
+    "exact, reduce or taper",
+    "What a radius too large for the geometry around the edges does: exact (the default) refuses it naming the largest that fits, reduce reduces it where it doesn't fit, taper follows the room along straight edges between planar faces. reduce and taper take type: constant. Matching ignores case."
+);
+keyword_param!(
+    /// `solid.fillet`'s `corner`.
+    FilletCornerParam,
+    "corner",
+    &["rolling", "g2"],
+    "rolling or g2",
+    "What fills a corner where three rounded edges meet: rolling (the default), the rolling ball's sphere, or g2, a set-back patch meeting the rounds to the second order (type: constant, fit: exact only). Matching ignores case."
+);
+keyword_param!(
+    /// `solid.fillet`'s `turn`.
+    FilletTurnParam,
+    "turn",
+    &["mitre", "swept"],
+    "mitre or swept",
+    "How two rounds turn round a sharp, straight, convex side edge square to both on a plane (the rounds along a boss's base, at its upright edges): mitre (the default) runs them on to meet in a mitre; swept ends them at the side edge and fills the corner with their section revolved about it, a torus. swept takes type: constant, corner: rolling, no setbacks and fit: exact or reduce, and is refused with the reason where the rounds are unequal or the side edge is concave, curved or tangent. Matching ignores case."
+);
+
 /// How a feature combines with existing bodies, as `features::operation` reads it.
 #[derive(Clone, Debug, PartialEq)]
 pub struct OperationParam(pub Operation);

crates/engine/src/schema/unconverted.txt

@@ -78,7 +78,6 @@ frame.member
 frame.profile.insert
 frame.profile.list
 frame.profile.properties
-inspect.clearance
 inspect.compare
 inspect.interference
 inspect.measure
@@ -107,8 +106,6 @@ material.delete
 material.edit
 material.inspect
 material.list
-material.properties.directional
-material.properties.validate
 mesh.convert
 motion.delete
 motion.export
@@ -308,7 +305,6 @@ solid.coil
 solid.combine
 solid.draft
 solid.emboss
-solid.fillet
 solid.hole
 solid.loft
 solid.mirror
@@ -333,7 +329,6 @@ surface.extend
 surface.extrude
 surface.fair
 surface.loft
-surface.match
 surface.offset
 surface.patch
 surface.reverse_normal

crates/engine/src/tests.rs

@@ -410,7 +410,6 @@ mod curved_seam_round;
 mod flush_join_loft;
 mod gltf_import;
 mod import_component;
-mod kernel_pool;
 mod large_step_import;
 mod loft_ring;
 mod loft_spacing;
@@ -3292,6 +3291,16 @@ fn unequal_chamfers_on_circular_rims() {
     assert!(rel(full - volume(&mut s), flipped) < 5e-3, "{} vs {flipped}", full - volume(&mut s));
 }
 
+/// A solid box top is not a rim: Lip says to Shell first (#10437).
+#[test]
+fn lip_on_a_solid_box_says_to_shell_first() {
+    let mut s = Session::default();
+    run(&mut s, "solid.box", json!({"length": 40, "width": 30, "height": 10}));
+    let err = s.execute("plastic.lip", &json!({"face": [20, 15, 10], "width": 1, "height": 2})).unwrap_err().to_string();
+    assert!(err.contains("Shell"), "{err}");
+    assert!(err.contains("rim") || err.contains("opening"), "{err}");
+}
+
 /// An enclosure built in the usual order: shell, bosses, then the lip on the rim.
 #[test]
 fn lip_after_boss() {

crates/engine/src/tests/kernel_pool.rs

@@ -1,181 +0,0 @@
-//! A design's bodies are made and used on whichever kernel of the pool is free
-//! (`solidcraft_smlib`'s `core::Pool`). What it builds must not depend on which: to the last
-//! number, on a new kernel or one that has done much, while another is busy, with bodies made on
-//! one kernel going into operations on another, through the evaluation cache, undo and redo.
-
-use super::*;
-
-/// A hole, a round and a chamfer, each building on the last.
-fn features() -> Vec<(&'static str, Value)> {
-    vec![
-        ("solid.box", json!({"length": 40, "width": 30, "height": 20})),
-        ("solid.cylinder", json!({"base": [12, 15, -1], "axis": [0, 0, 1], "radius": 3.4, "height": 30, "operation": "cut"})),
-        ("solid.fillet", json!({"edges": [[0, 0, 10]], "radius": 2})),
-        ("solid.chamfer", json!({"edges": [[20, 0, 20]], "distance": 1})),
-    ]
-}
-
-fn join() -> (&'static str, Value) {
-    ("solid.box", json!({"corner": [25, 10, 20], "length": 10, "width": 10, "height": 5, "operation": "join"}))
-}
-
-/// Everything a design built, exactly: each body's name, whole B-rep record and triangle count.
-fn built(s: &Session) -> Vec<String> {
-    let st = s.model.state();
-    st.bodies
-        .iter()
-        .map(|b| {
-            let record = serde_json::to_string(b.body.record()).unwrap();
-            format!("{} {} {record}", b.name, b.mesh().triangles.len())
-        })
-        .collect()
-}
-
-fn design(features: &[(&'static str, Value)]) -> Session {
-    let mut s = Session::default();
-    for (id, p) in features {
-        run(&mut s, id, p.clone());
-    }
-    s
-}
-
-fn assert_same(what: &str, a: &[String], b: &[String]) {
-    assert_eq!(a.len(), b.len(), "{what}: how many bodies");
-    assert!(a == b, "{what}: the design built differently");
-}
-
-#[test]
-fn a_design_rebuilds_the_same_on_any_kernel() {
-    let f = features();
-    let first = built(&design(&f));
-    assert!(!first.is_empty());
-    // On a new kernel, the one that built it above busy elsewhere.
-    let held = solidcraft_kernel::hold_a_kernel();
-    assert_same("a new kernel", &first, &built(&design(&f)));
-    // And another new one, with both of those out of use.
-    let held_too = solidcraft_kernel::hold_a_kernel();
-    assert_same("another new kernel", &first, &built(&design(&f)));
-    drop((held, held_too));
-    // On one that has built plenty since.
-    for _ in 0..3 {
-        design(&f);
-    }
-    assert_same("a kernel that did much before", &first, &built(&design(&f)));
-}
-
-/// A curvature round, whose procedural blends take their serials from the kernel: one body made
-/// on each of two kernels, the serials of neither mistaken for the other's in the kernel that
-/// solves stations for both.
-#[test]
-fn a_procedural_blend_builds_the_same_on_any_kernel() {
-    let f = vec![
-        ("solid.box", json!({"length": 40, "width": 30, "height": 20})),
-        ("solid.fillet", json!({"edges": [[20, 0, 20]], "radius": 3, "type": "curvature"})),
-    ];
-    let first = design(&f);
-    let held = solidcraft_kernel::hold_a_kernel();
-    let second = design(&f);
-    let b = built(&second);
-    assert_same("a new kernel", &built(&first), &b);
-    let v = |s: &mut Session| run(s, "inspect.measure", json!({}))["total"]["volume_mm3"].as_f64().unwrap();
-    let (mut first, mut second) = (first, second);
-    let beside = v(&mut second);
-    drop(held);
-    assert_eq!(v(&mut first).to_bits(), beside.to_bits(), "one measured right after the other on one kernel");
-}
-
-/// A modeled thread, a screw sweep and its boolean, on a short hole.
-#[test]
-fn a_thread_builds_the_same_on_any_kernel() {
-    let f = vec![
-        ("solid.box", json!({"length": 20, "width": 20, "height": 4})),
-        ("solid.cylinder", json!({"base": [10, 10, -1], "axis": [0, 0, 1], "radius": 3.4, "height": 10, "operation": "cut"})),
-        ("solid.thread", json!({"face": [13.4, 10, 2], "modeled": true})),
-    ];
-    let first = built(&design(&f));
-    let held = solidcraft_kernel::hold_a_kernel();
-    assert_same("a new kernel", &first, &built(&design(&f)));
-    drop(held);
-}
-
-/// Bodies from the evaluation cache and the undo stack go on into operations on another kernel:
-/// the join's boolean takes a body the held kernel made, undo restores it, redo brings back the
-/// join's, and each is what the whole design built in one go on a single kernel gives.
-#[test]
-fn bodies_from_another_kernel_go_on_through_the_cache_undo_and_redo() {
-    let f = features();
-    let mut all = f.clone();
-    all.push(join());
-    let (before, after) = (built(&design(&f)), built(&design(&all)));
-
-    let mut s = design(&f);
-    let held = solidcraft_kernel::hold_a_kernel();
-    let (id, p) = join();
-    run(&mut s, id, p);
-    assert_same("joined on another kernel", &after, &built(&s));
-    run(&mut s, "edit.undo", json!({}));
-    assert_same("undone", &before, &built(&s));
-    drop(held);
-    let held = solidcraft_kernel::hold_a_kernel();
-    run(&mut s, "edit.redo", json!({}));
-    assert_same("redone", &after, &built(&s));
-    // Rebuilt without the cache, every feature again, while that kernel stays out of use.
-    s.model.no_cache = true;
-    *s.model.cache.lock().unwrap() = Default::default();
-    run(&mut s, "timeline.roll_to", json!({"position": 0}));
-    run(&mut s, "timeline.roll_to", json!({}));
-    assert_same("rebuilt from the start", &after, &built(&s));
-    drop(held);
-    // And the body goes on from there, back on the first kernel.
-    run(&mut s, "solid.box", json!({"corner": [-5, 0, 0], "length": 5, "width": 5, "height": 5, "operation": "join"}));
-    let mut more = all.clone();
-    more.push(("solid.box", json!({"corner": [-5, 0, 0], "length": 5, "width": 5, "height": 5, "operation": "join"})));
-    assert_same("a further join", &built(&design(&more)), &built(&s));
-}
-
-/// A design rebuilt while other work keeps kernels of the pool busy on other threads builds what
-/// it builds alone, whichever kernels its calls happen to get.
-#[test]
-fn a_design_rebuilt_beside_other_work_builds_the_same() {
-    let f = features();
-    let alone = built(&design(&f));
-    let done = std::sync::Arc::new(std::sync::atomic::AtomicBool::new(false));
-    let busy: Vec<_> = (0..3)
-        .map(|_| {
-            let (done, f) = (done.clone(), f.clone());
-            std::thread::spawn(move || {
-                while !done.load(std::sync::atomic::Ordering::Relaxed) {
-                    design(&f);
-                }
-            })
-        })
-        .collect();
-    for _ in 0..3 {
-        assert_same("beside other work", &alone, &built(&design(&f)));
-    }
-    done.store(true, std::sync::atomic::Ordering::Relaxed);
-    for b in busy {
-        b.join().unwrap();
-    }
-}
-
-/// A copy that replaces its own design leaves the design it was copied from going: the token over
-/// that design's work is stopped only when that design itself closes or is replaced.
-#[test]
-fn a_copy_replacing_its_design_does_not_stop_the_design_it_came_from() {
-    let mut s = Session::default();
-    run(&mut s, "solid.box", json!({"length": 10, "width": 10, "height": 10}));
-    let token = s.stop_token();
-    let new = [("file.new".to_string(), json!({}))];
-    assert!(s.ahead().replies(&new).iter().all(Result::is_ok));
-    assert!(!token.is_stopped(), "a copy evaluating ahead");
-    let _ = s.scratch().compute_commands(&new, None);
-    assert!(!token.is_stopped(), "a copy computing a dialog's commands");
-    assert!(s.preview(&new).is_ok());
-    assert!(!token.is_stopped(), "a preview");
-    // It still works, and the design's own replacement does stop it.
-    run(&mut s, "solid.box", json!({"corner": [20, 0, 0], "length": 10, "width": 10, "height": 10}));
-    run(&mut s, "file.new", json!({}));
-    assert!(token.is_stopped(), "the design itself replaced");
-    assert!(!s.stop_token().is_stopped());
-}

crates/engine/src/thread_tests.rs

@@ -512,15 +512,127 @@ fn shaft_on_collar() -> Session {
 }
 
 /// Rig 602, ladder 06/004: a thread on a shaft ran a pitch past both ends of its face, into the
-/// collar below as into the air above. At a shoulder it stops with its widest part clear of it:
-/// the collar keeps its whole π 8² 10, and the groove takes (25 - w)/P turns, w its half width
-/// (a square stop inside material takes exactly its length over P, the section being symmetric).
+/// collar below as into the air above. It runs down to the shoulder and is trimmed at its plane
+/// (#11610): the collar keeps its whole π 8² 10, and the groove takes 25/P turns, each slice of
+/// the shaft along the axis losing the same.
 #[test]
-fn a_thread_stops_clear_of_a_shoulder() {
+fn a_thread_runs_down_to_a_shoulder_and_leaves_it_whole() {
     let mut s = shaft_on_collar();
     run(&mut s, "solid.thread", json!({"face": [5, 0, 25], "designation": "M10", "modeled": true}));
+    let want = PI * 64.0 * 10.0 + PI * 25.0 * 25.0 - 25.0 / 1.5 * ext_turn(10.0, 1.5, 5.0);
+    let got = exact_volume(&s, "Part");
+    assert!((got - want).abs() < want * 2e-4, "{got} vs {want}");
+}
+
+/// The volume of a body's part between two heights along Z, within a quadrant of X and Y when
+/// given (their signs).
+fn volume_between(s: &Session, b: &str, (z0, z1): (f64, f64), quadrant: Option<(bool, bool)>) -> f64 {
+    let st = s.model.state();
+    let mut part = st.body(b).unwrap().body.clone();
+    let on = |origin: Vec3, normal: Vec3| solidcore_record::Plane::from_normal(origin, normal.normalized().unwrap()).unwrap();
+    let z = Vec3::new(0.0, 0.0, 1.0);
+    let mut cuts = vec![(on(Vec3::new(0.0, 0.0, z0), z), true), (on(Vec3::new(0.0, 0.0, z1), z), false)];
+    if let Some((x, y)) = quadrant {
+        cuts.push((on(Vec3::ZERO, Vec3::new(1.0, 0.0, 0.0)), x));
+        cuts.push((on(Vec3::ZERO, Vec3::new(0.0, 1.0, 0.0)), y));
+    }
+    for (plane, positive) in cuts {
+        part = solidcraft_kernel::half_space(&part, &plane, positive).unwrap().0.unwrap();
+    }
+    solidcraft_kernel::measure(&part).unwrap().volume
+}
+
+/// #11610: a boss standing on a flat plate. The groove reaches the plate at every angle of the
+/// last turn, wherever the helix lands on it (each height a different gap under a pitch): a thin
+/// slice on the plate has lost as much as any slice of the thread, a pitch's slice as much in each
+/// quadrant (the uncut block of the old stop sat in some of them), and the plate is whole. Before,
+/// the last pitch kept up to a whole turn's groove uncut.
+#[test]
+fn a_thread_reaches_a_flat_shoulder_at_every_angle_and_leaves_it_whole() {
+    let (p, t, turn) = (1.5, 6.0, ext_turn(10.0, 1.5, 5.0));
+    let per_mm = PI * 25.0 - turn / p;
+    for (h, extra) in [
+        (16.0, json!({})),
+        (16.45, json!({})),
+        (16.6, json!({})),
+        (16.9, json!({})),
+        (17.4, json!({})),
+        (16.0, json!({"hand": "left"})),
+        (16.6, json!({"tip": "both"})),
+    ] {
+        let mut s = Session::default();
+        run(&mut s, "solid.box", json!({"corner": [-20, -20, 0], "length": 40, "width": 40, "height": t, "body_name": "Part"}));
+        run(&mut s, "solid.cylinder", json!({"base": [0, 0, t], "radius": 5, "height": h, "operation": "join", "targets": ["Part"]}));
+        let mut ask = json!({"face": [5, 0, t + h / 2.0], "designation": "M10", "modeled": true});
+        if let (Some(a), Value::Object(e)) = (ask.as_object_mut(), &extra) {
+            a.extend(e.clone());
+        }
+        run(&mut s, "solid.thread", ask);
+        let name = format!("h {h} {extra}");
+        assert!(s.model.state().body("Part").unwrap().body.validity().is_empty(), "{name}");
+        let plate = volume_between(&s, "Part", (-1.0, t), None);
+        assert!((plate - 1600.0 * t).abs() < 1e-6 * 1600.0 * t, "{name}: the plate lost {} mm³", 1600.0 * t - plate);
+        let thin = volume_between(&s, "Part", (t, t + 0.1 * p), None);
+        let want = per_mm * 0.1 * p;
+        assert!((thin - want).abs() < want * 2e-3, "{name}: the slice on the plate is {thin}, not {want}");
+        for quadrant in [(true, true), (true, false), (false, true), (false, false)] {
+            let got = volume_between(&s, "Part", (t, t + p), Some(quadrant));
+            let want = per_mm * p / 4.0;
+            assert!((got - want).abs() < want * 2e-3, "{name}: {quadrant:?} of the last pitch is {got}, not {want}");
+        }
+    }
+}
+
+/// #11610: where a shoulder is not flat. A fillet or a chamfer at the shaft's base stays whole, the
+/// groove trimmed where the face ends above it. A shoulder that rises back along the face (a
+/// slanted plate, a boss on a round body) would be cut by a groove running to the plane of the
+/// face's lowest point, so the groove keeps its square stop there. Nothing here fails.
+#[test]
+fn a_thread_at_a_shoulder_that_is_not_flat_still_builds() {
+    let (p, turn) = (1.5, ext_turn(10.0, 1.5, 5.0));
+    let plate = |s: &mut Session| {
+        run(s, "solid.box", json!({"corner": [-20, -20, 0], "length": 40, "width": 40, "height": 6, "body_name": "Part"}));
+        run(s, "solid.cylinder", json!({"base": [0, 0, 6], "radius": 5, "height": 16, "operation": "join", "targets": ["Part"]}));
+    };
+    for finish in [("solid.fillet", json!({"edges": [[5, 0, 6]], "radius": 1})), ("solid.chamfer", json!({"edges": [[5, 0, 6]], "distance": 1}))] {
+        let mut s = Session::default();
+        plate(&mut s);
+        run(&mut s, finish.0, finish.1);
+        let (base, shaft) = (volume_between(&s, "Part", (-1.0, 7.0), None), exact_volume(&s, "Part"));
+        run(&mut s, "solid.thread", json!({"face": [5, 0, 15], "designation": "M10", "modeled": true}));
+        assert!(s.model.state().body("Part").unwrap().body.validity().is_empty(), "{}", finish.0);
+        let left = volume_between(&s, "Part", (-1.0, 7.0), None);
+        assert!((left - base).abs() < 1e-6 * base, "{}: the base lost {} mm³", finish.0, base - left);
+        let (got, want) = (exact_volume(&s, "Part"), shaft - 15.0 / p * turn);
+        assert!((got - want).abs() < want * 2e-4, "{}: {got} vs {want}", finish.0);
+    }
+    let rising = [
+        vec![("solid.cylinder", json!({"base": [0, 0, 0], "axis": [0.2, 0, 1], "radius": 20, "height": 6, "body_name": "Part"}))],
+        vec![("solid.cylinder", json!({"base": [0, -20, 0], "axis": [0, 1, 0], "radius": 10, "height": 40, "body_name": "Part"}))],
+    ];
+    for cmds in rising {
+        let mut s = Session::default();
+        for (c, ask) in cmds {
+            run(&mut s, c, ask);
+        }
+        run(&mut s, "solid.cylinder", json!({"base": [0, 0, 2], "radius": 5, "height": 26, "operation": "join", "targets": ["Part"]}));
+        let before = exact_volume(&s, "Part");
+        run(&mut s, "solid.thread", json!({"face": [5, 0, 20], "designation": "M10", "modeled": true}));
+        assert!(s.model.state().body("Part").unwrap().body.validity().is_empty());
+        assert!(exact_volume(&s, "Part") < before);
+    }
+}
+
+/// #11610: the trim is for a thread that runs the whole face. A length stopping short of the
+/// shoulder still stops there, however near.
+#[test]
+fn a_thread_of_some_length_stops_where_it_is_told_short_of_a_shoulder() {
     let (p, w) = (1.5, ext_half_width(10.0, 1.5));
-    let want = PI * 64.0 * 10.0 + PI * 25.0 * 25.0 - (25.0 - w) / p * ext_turn(10.0, p, 5.0);
+    let mut s = shaft_on_collar();
+    let before = exact_volume(&s, "Part");
+    run(&mut s, "solid.thread", json!({"face": [5, 0, 25], "designation": "M10", "length": 24.6, "modeled": true}));
+    // Its end is within half a pitch of the shoulder: the stop stays clear of it.
+    let want = before - (24.6f64).min(25.0 - w) / p * ext_turn(10.0, p, 5.0);
     let got = exact_volume(&s, "Part");
     assert!((got - want).abs() < want * 2e-4, "{got} vs {want}");
 }
@@ -528,7 +640,7 @@ fn a_thread_stops_clear_of_a_shoulder() {
 /// A d10 boss (z t..t+16) on a plate t thick, threaded M10: the plate's top is the shoulder.
 /// The groove, with or without its runout, stays on the boss: the plate keeps all of itself
 /// (what lies below z = t after the boss is cut away), and without a runout the boss loses
-/// (16 - w)/P turns, as at a collar. The owner's bug: built as the app builds it (a rounded
+/// 16/P turns, as at a collar. The owner's bug: built as the app builds it (a rounded
 /// plate, a circle sketched on its top face and extruded with Join), a plate thinner than 1.5 P
 /// had no material where the free-end test looked (1 to 1.5 pitches past the face), so its top
 /// was taken for a free end and the overrun cut a pitch into it.
@@ -562,10 +674,10 @@ fn a_thread_on_a_boss_never_cuts_into_the_plate_below() {
         exact_volume(&s, "Body1")
     };
     let plate = |t: f64| (40.0 * 40.0 - (4.0 - PI) * 25.0) * t;
-    let (p, w) = (1.5, ext_half_width(10.0, 1.5));
+    let p = 1.5;
     for t in [6.0, 1.0] {
         let s = boss(t, json!({}));
-        let want = plate(t) + PI * 25.0 * 16.0 - (16.0 - w) / p * ext_turn(10.0, p, 5.0);
+        let want = plate(t) + PI * 25.0 * 16.0 - 16.0 / p * ext_turn(10.0, p, 5.0);
         let got = exact_volume(&s, "Body1");
         assert!((got - want).abs() < want * 2e-4, "plate {t}: {got} vs {want}");
         let left = plate_left(s, t);
@@ -915,10 +1027,9 @@ fn a_chamfered_tip_tapers_the_last_teeth() {
         "solid.thread",
         json!({"face": [5, 0, 25], "designation": "M10", "tip": "both", "chamfer_angle": "30 deg", "chamfer_depth": 0.5, "modeled": true}),
     );
-    let w = ext_half_width(10.0, 1.5);
     let rf = 4.5;
     let slope = 30f64.to_radians().tan();
-    let want = PI * 64.0 * 10.0 + PI * 25.0 * w + m10_stock(10.0 + w, 35.0, |z| 5f64.min(rf + (35.0 - z) * slope));
+    let want = PI * 64.0 * 10.0 + m10_stock(10.0, 35.0, |z| 5f64.min(rf + (35.0 - z) * slope));
     let got = exact_volume(&s, "Part");
     assert!((got - want).abs() < want * 1e-4, "{got} vs {want}");
     // Internal threads take a countersink instead.
@@ -1004,7 +1115,8 @@ fn a_runout_fades_the_groove_out_before_the_shoulder() {
     let (p, w) = (1.5, ext_half_width(10.0, 1.5));
     let root = 5.0 - 5.0 * p * 3f64.sqrt() / 16.0;
     let h = 5.0 - root + 0.05 * p;
-    let turns = (35.0 - 10.0 - 2.0 * w) / p;
+    // Trimmed at the bottom collar's plane, stopped clear of the top one for its runout.
+    let turns = (35.0 - 10.0 - w) / p;
     for (ease, r_out) in [(json!("short"), 1.25), (json!("standard"), 2.5), (json!("1 mm"), 1.0 / 1.5)] {
         let mut s = shaft_on_collar();
         run(&mut s, "solid.cylinder", json!({"base": [0, 0, 35], "radius": 8, "height": 10, "operation": "join", "targets": ["Part"]}));

crates/io/src/lib.rs

@@ -1296,6 +1296,7 @@ mod tests {
                 fit: Default::default(),
                 corner: Default::default(),
                 setbacks: Vec::new(),
+                turn: Default::default(),
                 tangent_chain: true,
             },
             None,
@@ -1418,6 +1419,7 @@ mod tests {
                 fit: Default::default(),
                 corner: Default::default(),
                 setbacks: Vec::new(),
+                turn: Default::default(),
                 tangent_chain: true,
             },
             None,

crates/kernel/src/blend.rs

@@ -234,22 +234,40 @@ fn closed(input: &Body, b: Body) -> Result<Body> {
     }
 }
 
+/// How two constant rounds of one radius turn round a sharp, straight, convex side edge square to
+/// both on a plane, such as the rounds along a boss's base at its upright edges.
+#[derive(Clone, Copy, Debug, Default, PartialEq, Eq)]
+pub enum FilletTurn {
+    /// The rounds run on to where they cross and meet in a mitre.
+    #[default]
+    Mitre,
+    /// The rounds end at the side edge and the corner is their section revolved about it, a
+    /// torus tangent to both. Refused where it is not built (unequal or variable rounds, a
+    /// concave, curved or tangent side edge, a corner of four edges), with the reason.
+    Swept,
+}
+
 /// Constant-radius fillet of the edges nearest to the given points. A radius too large for the
 /// faces around the edges is refused with [`KernelError::TooLarge`] ([`fillet_max`] finds the
 /// largest that works).
 pub fn fillet(body: &Body, edges: &[Vec3], radius: f64) -> Result<Body> {
-    let _span = solidcraft_profile::span("kernel", "fillet");
-    body.require_brep("fillet")?;
-    crate::blend_smlib::fillet(body, edges, radius).and_then(|b| closed(body, b))
+    fillet_turning(body, edges, radius, FilletTurn::Mitre)
 }
 
-/// [`fillet`], with the picks whose edges are gone: where some of the rounds overflow their
-/// faces, those are built first, and a picked edge one of them removes whole is not rounded (the
-/// others round what is left of their edges).
-pub fn fillet_removing(body: &Body, edges: &[Vec3], radius: f64) -> Result<(Body, Vec<Vec3>)> {
+/// [`fillet`], its rounds turning at side edges as `turn` says.
+fn fillet_turning(body: &Body, edges: &[Vec3], radius: f64, turn: FilletTurn) -> Result<Body> {
     let _span = solidcraft_profile::span("kernel", "fillet");
     body.require_brep("fillet")?;
-    let (b, gone) = crate::blend_smlib::fillet_removing(body, edges, radius)?;
+    crate::blend_smlib::fillet(body, edges, radius, turn).and_then(|b| closed(body, b))
+}
+
+/// [`fillet`], its rounds turning at side edges as `turn` says, with the picks whose edges are
+/// gone: where some of the rounds overflow their faces, those are built first, and a picked edge
+/// one of them removes whole is not rounded (the others round what is left of their edges).
+pub fn fillet_removing(body: &Body, edges: &[Vec3], radius: f64, turn: FilletTurn) -> Result<(Body, Vec<Vec3>)> {
+    let _span = solidcraft_profile::span("kernel", "fillet");
+    body.require_brep("fillet")?;
+    let (b, gone) = crate::blend_smlib::fillet_removing(body, edges, radius, turn)?;
     Ok((closed(body, b)?, gone))
 }
 
@@ -515,10 +533,11 @@ fn radius_step(radius: f64) -> f64 {
 /// them (a refusal of a fillet feature's exact fit runs it to name the largest that fits, and
 /// so does `fit: reduce`). Only a refusal as too large
 /// ([`KernelError::TooLarge`]) narrows the search: any other failure of a candidate is the
-/// search's error, since a smaller radius would not be the largest that fits.
-pub fn fillet_max(body: &Body, edges: &[Vec3], radius: f64) -> Result<Option<(f64, Body)>> {
+/// search's error, since a smaller radius would not be the largest that fits. The rounds turn at
+/// side edges as `turn` says.
+pub fn fillet_max(body: &Body, edges: &[Vec3], radius: f64, turn: FilletTurn) -> Result<Option<(f64, Body)>> {
     let _span = solidcraft_profile::span("kernel", "fillet_max");
-    largest_that_fits(radius, |r| fillet(body, edges, r))
+    largest_that_fits(radius, |r| fillet_turning(body, edges, r, turn))
 }
 
 /// [`fillet_max`] for an equal-distance chamfer of these edges: the largest distance below
@@ -566,21 +585,21 @@ fn largest_that_fits(size: f64, blend: impl Fn(f64) -> Result<Body>) -> Result<O
 /// each reduced to fit, are too large together, or there are too many to search (each search is
 /// up to 16 fillets, and this runs in the live preview). Any failure other than a refusal as too
 /// large is the error.
-pub fn fillet_max_each(body: &Body, edges: &[Vec3], radius: f64) -> Result<Option<(Vec<f64>, Body)>> {
+pub fn fillet_max_each(body: &Body, edges: &[Vec3], radius: f64, turn: FilletTurn) -> Result<Option<(Vec<f64>, Body)>> {
     let _span = solidcraft_profile::span("kernel", "fillet_max_each");
     const MAX_GROUPS: usize = 8;
     const MAX_SEARCHES: usize = 2;
-    let one = || -> Result<Option<(Vec<f64>, Body)>> { Ok(fillet_max(body, edges, radius)?.map(|(r, b)| (vec![r; edges.len()], b))) };
+    let one = || -> Result<Option<(Vec<f64>, Body)>> { Ok(fillet_max(body, edges, radius, turn)?.map(|(r, b)| (vec![r; edges.len()], b))) };
     let Some(groups) = interacting_groups(body, edges).filter(|g| g.len() > 1 && g.len() <= MAX_GROUPS) else { return one() };
     let mut radii = vec![radius; edges.len()];
     let mut searches = 0;
     for g in &groups {
         let pts: Vec<Vec3> = g.iter().filter_map(|i| edges.get(*i).copied()).collect();
-        let r = match fillet(body, &pts, radius) {
+        let r = match fillet_turning(body, &pts, radius, turn) {
             Ok(_) => continue,
             Err(KernelError::TooLarge(_)) if searches < MAX_SEARCHES => {
                 searches += 1;
-                match fillet_max(body, &pts, radius)? {
+                match fillet_max(body, &pts, radius, turn)? {
                     Some((r, _)) => r,
                     None => return one(),
                 }
@@ -594,7 +613,7 @@ pub fn fillet_max_each(body: &Body, edges: &[Vec3], radius: f64) -> Result<Optio
             }
         }
     }
-    match fillet_each(body, edges, &radii) {
+    match fillet_each(body, edges, &radii, turn) {
         Ok(b) => Ok(Some((radii, b))),
         Err(KernelError::TooLarge(_)) => one(),
         Err(e) => Err(e),
@@ -603,16 +622,16 @@ pub fn fillet_max_each(body: &Body, edges: &[Vec3], radius: f64) -> Result<Optio
 
 /// The fillet of each edge at its own radius (`radii` in `edges`' order), all in one SMLib
 /// blend.
-pub fn fillet_each(body: &Body, edges: &[Vec3], radii: &[f64]) -> Result<Body> {
+pub fn fillet_each(body: &Body, edges: &[Vec3], radii: &[f64], turn: FilletTurn) -> Result<Body> {
     let _span = solidcraft_profile::span("kernel", "fillet_each");
     if radii.len() != edges.len() {
         return Err(KernelError::Invalid("one radius per edge".into()));
     }
     if let Some(r) = radii.first().filter(|r| radii.iter().all(|x| x.to_bits() == r.to_bits())) {
-        return fillet(body, edges, *r);
+        return fillet_turning(body, edges, *r, turn);
     }
     body.require_brep("fillet")?;
-    crate::blend_smlib::fillet_each(body, edges, radii).and_then(|b| closed(body, b))
+    crate::blend_smlib::fillet_each(body, edges, radii, turn).and_then(|b| closed(body, b))
 }
 
 /// The points' edges (each the edge a blend's pick there takes) grouped where they share a face
@@ -1599,7 +1618,7 @@ mod tests {
         assert!(matches!(e, KernelError::TooLarge(_)), "{e}");
         let e = e.to_string();
         assert!(e.contains("into the hollow at (0.000, 30.000, 40.000) and open the part"), "{e}");
-        let (largest, _) = fillet_max(&case, &[top], 7.0).unwrap().unwrap();
+        let (largest, _) = fillet_max(&case, &[top], 7.0, FilletTurn::Mitre).unwrap().unwrap();
         assert!((largest - 6.828).abs() < 1e-9, "{largest}");
 
         // Just short of the corner it rounds, its whole section along the 104.
@@ -1613,8 +1632,8 @@ mod tests {
         // inner R7's arc (centre (23, 33)) only at sqrt2 (r - 9) + 7 = r, r = 13.83.
         let inside = Vec3::new(0.0, 30.0, 40.0);
         assert!(fillet(&case, &[top, inside], 7.0).is_ok());
-        assert!(fillet_each(&case, &[top, inside], &[13.8, 7.0]).is_ok());
-        let e = fillet_each(&case, &[top, inside], &[13.9, 7.0]).unwrap_err().to_string();
+        assert!(fillet_each(&case, &[top, inside], &[13.8, 7.0], FilletTurn::Mitre).is_ok());
+        let e = fillet_each(&case, &[top, inside], &[13.9, 7.0], FilletTurn::Mitre).unwrap_err().to_string();
         assert!(e.contains("into the hollow at"), "{e}");
     }
 

crates/kernel/src/blend_corner.rs

@@ -261,7 +261,7 @@ pub fn fillet_radii(body: &Body, edges: &[(Vec3, f64)]) -> Result<Body> {
         return Err(KernelError::Invalid("fillet size must be positive".into()));
     }
     let (points, radii): (Vec<Vec3>, Vec<f64>) = edges.iter().copied().unzip();
-    crate::blend_smlib::fillet_each(body, &points, &radii)
+    crate::blend_smlib::fillet_each(body, &points, &radii, crate::FilletTurn::Mitre)
 }
 
 #[cfg(test)]

crates/kernel/src/blend_smlib.rs

@@ -17,7 +17,7 @@ use solidcore_record::Vec3;
 
 use crate::blend_variable::RadiusSpline;
 use crate::body::Body;
-use crate::{KernelError, Result};
+use crate::{FilletTurn, KernelError, Result};
 
 /// What SMLib cannot build yet.
 pub(crate) fn unsupported(what: &str) -> KernelError {
@@ -25,22 +25,24 @@ pub(crate) fn unsupported(what: &str) -> KernelError {
 }
 
 /// A constant-radius round of the edges nearest `edges` ([`crate::fillet`]).
-pub(crate) fn fillet(body: &Body, edges: &[Vec3], radius: f64) -> Result<Body> {
-    imp::blend(body, "fillet", Kind::Round, edges, &vec![radius; edges.len()])
+/// The rounds turn at side edges as `turn` says.
+pub(crate) fn fillet(body: &Body, edges: &[Vec3], radius: f64, turn: FilletTurn) -> Result<Body> {
+    imp::blend(body, "fillet", Kind::Round(turn), edges, &vec![radius; edges.len()])
 }
 
 /// [`fillet`], with the picks whose edges a larger, overflowing round removed whole.
-pub(crate) fn fillet_removing(body: &Body, edges: &[Vec3], radius: f64) -> Result<(Body, Vec<Vec3>)> {
-    let (b, dropped) = imp::blend_dropping(body, "fillet", Kind::Round, edges, &vec![radius; edges.len()])?;
+pub(crate) fn fillet_removing(body: &Body, edges: &[Vec3], radius: f64, turn: FilletTurn) -> Result<(Body, Vec<Vec3>)> {
+    let (b, dropped) = imp::blend_dropping(body, "fillet", Kind::Round(turn), edges, &vec![radius; edges.len()])?;
     Ok((b, edges.iter().zip(dropped).filter(|(_, d)| *d).map(|(p, _)| *p).collect()))
 }
 
-/// Each edge rounded at its own radius ([`crate::fillet_each`]).
-pub(crate) fn fillet_each(body: &Body, edges: &[Vec3], radii: &[f64]) -> Result<Body> {
+/// Each edge rounded at its own radius ([`crate::fillet_each`]), turning at side edges as `turn`
+/// says.
+pub(crate) fn fillet_each(body: &Body, edges: &[Vec3], radii: &[f64], turn: FilletTurn) -> Result<Body> {
     if radii.len() != edges.len() {
         return Err(KernelError::Invalid("one radius per edge".into()));
     }
-    imp::blend(body, "fillet", Kind::Round, edges, radii)
+    imp::blend(body, "fillet", Kind::Round(turn), edges, radii)
 }
 
 /// A constant-radius round whose corners at `setbacks` (a point at each corner's vertex, and the
@@ -63,7 +65,7 @@ pub(crate) struct OpenCorners {
 /// that would fill each corner, for the caller to fill.
 /// `curvature`: the rounds' sections are curvature-continuous ([`fillet_g2`]), else circular.
 pub(crate) fn fillet_setback_open(body: &Body, edges: &[Vec3], radius: f64, setbacks: &[(Vec3, f64)], curvature: bool) -> Result<OpenCorners> {
-    let kind = if curvature { Kind::Curvature } else { Kind::Round };
+    let kind = if curvature { Kind::Curvature } else { Kind::Round(FilletTurn::Mitre) };
     imp::blend_setback_open(body, kind, edges, &vec![radius; edges.len()], setbacks)
 }
 
@@ -104,7 +106,8 @@ pub(crate) fn picked_edges(body: &Body, picks: &[Vec3]) -> Result<(Vec<usize>, V
 
 #[derive(Clone, Copy)]
 enum Kind {
-    Round,
+    /// Constant-radius rounds, turning at side edges as the [`FilletTurn`] says.
+    Round(FilletTurn),
     Curvature,
     Chord,
     Chamfer,
@@ -115,7 +118,7 @@ mod imp {
     use std::collections::BTreeSet;
 
     use solidcore_record::Vec3;
-    use solidcraft_smlib::{Blend, Brep, ChamferSecond, CheckLevel, Error as SmError};
+    use solidcraft_smlib::{Blend, Brep, ChamferSecond, CheckLevel, Error as SmError, Turn};
 
     use super::Kind;
     use crate::blend_variable::RadiusSpline;
@@ -225,13 +228,21 @@ mod imp {
     /// SMLib's blend of each kind.
     fn blend_kind(kind: Kind) -> Blend {
         match kind {
-            Kind::Round => Blend::Round,
+            Kind::Round(_) => Blend::Round,
             Kind::Curvature => Blend::Curvature,
             Kind::Chord => Blend::Chord,
             Kind::Chamfer => Blend::Chamfer,
         }
     }
 
+    /// SMLib's turn of each kind of turn.
+    fn smlib_turn(turn: crate::FilletTurn) -> Turn {
+        match turn {
+            crate::FilletTurn::Mitre => Turn::Mitre,
+            crate::FilletTurn::Swept => Turn::Swept,
+        }
+    }
+
     pub(super) fn blend(body: &Body, what: &str, kind: Kind, edges: &[Vec3], sizes: &[f64]) -> Result<Body> {
         blend_dropping(body, what, kind, edges, sizes).map(|(b, _)| b)
     }
@@ -243,21 +254,22 @@ mod imp {
         sizes_ok(what, sizes)?;
         let picked = resolve(body, edges)?;
         let next = crate::blend::unfinished_chain(body, edges, &picked.edges, &picked.hidden)?;
-        if matches!(kind, Kind::Round) {
+        if matches!(kind, Kind::Round(_)) {
             crate::blend::rounds_too_small(body, edges, &picked.edges, sizes)?;
             crate::blend::rounds_into_hollow(body, edges, &picked.edges, sizes)?;
         }
         let tol = pick_tolerance(body);
-        let Kind::Round = kind else {
+        let Kind::Round(turn) = kind else {
             let kind = blend_kind(kind);
-            return run_with(body, what, &picked.edges, &[], |b| b.blend_dropping(kind, &picked.points, sizes, tol))
+            return run_with(body, what, &picked.edges, &[], |b| b.blend_dropping(kind, Turn::Mitre, &picked.points, sizes, tol))
                 .map(|(out, dropped, _)| (out, dropped))
                 .map_err(|e| crate::blend::with_continuation(e, next));
         };
         // Constant-radius rounds: the body keeps what they were made on, and a later round at a
         // corner where they meet blends them again with it (crate::blend_corner).
+        let turn = smlib_turn(turn);
         let out = match crate::blend_corner::later_corners(body, &picked.edges, sizes)? {
-            Some((later, new)) => reblend(body, what, &later).map(|(b, dropped_new)| {
+            Some((later, new)) => reblend(body, what, &later, turn).map(|(b, dropped_new)| {
                 // A picked seam has no round of its own: only the new edges can be removed.
                 let dropped = picked
                     .edges
@@ -266,7 +278,7 @@ mod imp {
                     .collect();
                 (b.with_rounds(body, new), dropped)
             }),
-            None => run_with(body, what, &picked.edges, &[], |b| b.blend_dropping(Blend::Round, &picked.points, sizes, tol))
+            None => run_with(body, what, &picked.edges, &[], |b| b.blend_dropping(Blend::Round, turn, &picked.points, sizes, tol))
                 .map(|(out, dropped, _)| (out.with_rounds(body, picked.edges.iter().copied().zip(sizes.iter().copied()).collect()), dropped)),
         };
         out.map_err(|e| crate::blend::with_continuation(e, next))
@@ -275,8 +287,9 @@ mod imp {
     /// The blend `later` makes of its base, every round from the earliest meeting the new edges'
     /// corners on and the new edges in one, with its history over `body`, the body the later
     /// round was given ([`crate::blend_corner::rebase`]), and whether each new edge (in
-    /// `later`'s order) was removed whole by a larger, overflowing round.
-    fn reblend(body: &Body, what: &str, later: &crate::blend_corner::Later) -> Result<(Body, Vec<bool>)> {
+    /// `later`'s order) was removed whole by a larger, overflowing round. The rounds turn at side
+    /// edges as `turn` says.
+    fn reblend(body: &Body, what: &str, later: &crate::blend_corner::Later, turn: Turn) -> Result<(Body, Vec<bool>)> {
         let base = &later.base;
         let mesh = base.mesh(&crate::MeshTolerance::chord((base.size() * 2e-3).max(1e-3)))?;
         let mut indices = Vec::with_capacity(later.edges.len());
@@ -291,7 +304,7 @@ mod imp {
         }
         sizes_ok(what, &radii)?;
         let tol = pick_tolerance(base);
-        let (out, dropped, _) = run_with(base, what, &indices, &[], |b| b.blend_dropping(Blend::Round, &points, &radii, tol))?;
+        let (out, dropped, _) = run_with(base, what, &indices, &[], |b| b.blend_dropping(Blend::Round, turn, &points, &radii, tol))?;
         // The new edges are the last of `later.edges`.
         let dropped_new = dropped.get(dropped.len().saturating_sub(later.new_count())..).map(<[bool]>::to_vec).unwrap_or_default();
         let history = out.history().and_then(|h| crate::blend_corner::rebase(h, later, body));
@@ -446,6 +459,11 @@ mod imp {
                      run on tangentially into each other, or meet in a way no blend corner builds)"
                 )),
                 SmError::NoRoom => KernelError::TooLarge(format!("the {what} is larger than the faces beside its edges allow")),
+                // Not a size a smaller radius fixes: solidcore builds no swept turn there.
+                SmError::TurnRefused { why, at, .. } => {
+                    let at = at.map(|[x, y, z]| format!(" at ({x:.3}, {y:.3}, {z:.3})")).unwrap_or_default();
+                    KernelError::Invalid(format!("the {what}'s swept corner{at} is not built: {why}"))
+                }
                 SmError::TooLarge { size, kind, at, why } => {
                     let mut beside = match at {
                         Some([x, y, z]) => format!(", at the edge at ({x:.3}, {y:.3}, {z:.3})"),
@@ -594,7 +612,7 @@ mod tests {
     fn a_round_loses_its_corner_and_its_face_comes_from_the_edge() {
         let b = cube();
         let at = Vec3::new(10.0, 20.0, 20.0);
-        let r = imp::blend(&b, "fillet", Kind::Round, &[at], &[2.0]).unwrap();
+        let r = imp::blend(&b, "fillet", Kind::Round(FilletTurn::Mitre), &[at], &[2.0]).unwrap();
         assert!(near(volume(&r), 8000.0 - QUARTER * 4.0 * 20.0), "{}", volume(&r));
         assert_eq!(r.face_count(), 7);
         let h = r.history().expect("a history");
@@ -608,8 +626,8 @@ mod tests {
         // (20, 20, 10) is on the vertical edge only; (20, 20, 20) is a corner of three edges, which
         // the body's own order resolves, never left to SMLib.
         let b = cube();
-        assert!(imp::blend(&b, "fillet", Kind::Round, &[Vec3::new(20.0, 20.0, 20.0)], &[1.0]).is_ok());
-        assert!(imp::blend(&b, "fillet", Kind::Round, &[Vec3::new(60.0, 60.0, 60.0)], &[1.0]).is_err());
+        assert!(imp::blend(&b, "fillet", Kind::Round(FilletTurn::Mitre), &[Vec3::new(20.0, 20.0, 20.0)], &[1.0]).is_ok());
+        assert!(imp::blend(&b, "fillet", Kind::Round(FilletTurn::Mitre), &[Vec3::new(60.0, 60.0, 60.0)], &[1.0]).is_err());
     }
 
     /// A ball's rim on a block's back face, tangent to the back face's bottom edge at (2.5, 22.5, 0).
@@ -677,7 +695,7 @@ mod tests {
     fn each_edge_takes_its_own_size() {
         let b = cube();
         let picks = [Vec3::new(10.0, 20.0, 20.0), Vec3::new(10.0, 0.0, 20.0)];
-        let r = imp::blend(&b, "fillet", Kind::Round, &picks, &[2.0, 3.0]).unwrap();
+        let r = imp::blend(&b, "fillet", Kind::Round(FilletTurn::Mitre), &picks, &[2.0, 3.0]).unwrap();
         assert!(near(volume(&r), 8000.0 - QUARTER * 13.0 * 20.0), "{}", volume(&r));
         let c = imp::blend(&b, "chamfer", Kind::Chamfer, &picks, &[2.0, 3.0]).unwrap();
         assert!(near(volume(&c), 8000.0 - 0.5 * 13.0 * 20.0), "{}", volume(&c));
@@ -750,9 +768,9 @@ mod tests {
         // A radius law down to zero inside the edge would pinch the round to a point.
         let pinch = RadiusSpline { degree: 1, knots: vec![0.0, 0.0, 0.5, 1.0, 1.0], radii: vec![4.0, 0.0, 4.0] };
         assert!(imp::variable(&b, Vec3::new(10.0, 20.0, 20.0), Vec3::new(0.0, 20.0, 20.0), &pinch).is_err());
-        assert!(imp::blend(&b, "fillet", Kind::Round, &[Vec3::new(10.0, 20.0, 20.0)], &[f64::NAN]).is_err());
-        assert!(imp::blend(&b, "fillet", Kind::Round, &[Vec3::new(f64::NAN, 20.0, 20.0)], &[1.0]).is_err());
-        assert!(imp::blend(&b, "fillet", Kind::Round, &[], &[]).is_err());
+        assert!(imp::blend(&b, "fillet", Kind::Round(FilletTurn::Mitre), &[Vec3::new(10.0, 20.0, 20.0)], &[f64::NAN]).is_err());
+        assert!(imp::blend(&b, "fillet", Kind::Round(FilletTurn::Mitre), &[Vec3::new(f64::NAN, 20.0, 20.0)], &[1.0]).is_err());
+        assert!(imp::blend(&b, "fillet", Kind::Round(FilletTurn::Mitre), &[], &[]).is_err());
     }
 
     /// A smooth edge (a round's seam with the face it runs into) has nothing to round: refused
@@ -764,30 +782,30 @@ mod tests {
     #[test]
     fn smooth_edges_and_unfinished_tangent_chains_are_refused_saying_why() {
         let b = cube();
-        let rounded = fillet(&b, &[Vec3::new(10.0, 20.0, 20.0)], 3.0).unwrap();
+        let rounded = fillet(&b, &[Vec3::new(10.0, 20.0, 20.0)], 3.0, FilletTurn::Mitre).unwrap();
         // the seam where the r3 round meets the top, 3 in from the old edge
-        let seam = imp::blend(&rounded, "fillet", Kind::Round, &[Vec3::new(10.0, 17.0, 20.0)], &[1.0]).unwrap_err().to_string();
+        let seam = imp::blend(&rounded, "fillet", Kind::Round(FilletTurn::Mitre), &[Vec3::new(10.0, 17.0, 20.0)], &[1.0]).unwrap_err().to_string();
         assert!(seam.contains("is smooth: its faces meet tangentially, so there is nothing to round"), "{seam}");
         // the end face's top edge runs on tangentially into the round's end arc: its r1 round
         // goes on along y through the r3 round until that drops below it, at y = 17 + sqrt(5)
         // (the rig case's closed form: 8000 - 20 (9 - 9 pi/4) - 17 (1 - pi/4) - 0.218236)
         let top = Vec3::new(0.0, 8.0, 20.0);
-        let alone = fillet(&rounded, &[top], 1.0).unwrap();
+        let alone = fillet(&rounded, &[top], 1.0, FilletTurn::Mitre).unwrap();
         assert!((volume(&alone) - 7957.505202).abs() < 1e-3, "{}", volume(&alone));
         let chain = crate::tangent_chain(&rounded, &[top]).unwrap();
         assert!(chain.len() > 1, "{chain:?}");
-        let whole = fillet(&rounded, &chain, 1.0).unwrap();
+        let whole = fillet(&rounded, &chain, 1.0, FilletTurn::Mitre).unwrap();
         assert!(volume(&whole) < volume(&rounded));
 
         // r5 and r3 on two top edges at a corner, then r2 on the vertical edge under them: it
         // runs on up the r5 round's end arc, and SMLib ends it there
         let b = box_solid(Vec3::new(0.0, 0.0, 0.0), Vec3::new(60.0, 40.0, 20.0)).unwrap();
-        let b = fillet(&b, &[Vec3::new(30.0, 40.0, 20.0)], 5.0).unwrap();
-        let b = fillet(&b, &[Vec3::new(60.0, 20.0, 20.0)], 3.0).unwrap();
+        let b = fillet(&b, &[Vec3::new(30.0, 40.0, 20.0)], 5.0, FilletTurn::Mitre).unwrap();
+        let b = fillet(&b, &[Vec3::new(60.0, 20.0, 20.0)], 3.0, FilletTurn::Mitre).unwrap();
         let vertical = Vec3::new(60.0, 40.0, 8.0);
         let chain = crate::tangent_chain(&b, &[vertical]).unwrap();
         assert!(chain.len() > 1, "{chain:?}");
-        let run_on = fillet(&b, &[vertical], 2.0).unwrap();
+        let run_on = fillet(&b, &[vertical], 2.0, FilletTurn::Mitre).unwrap();
         assert!(volume(&run_on) < volume(&b));
     }
 }

crates/kernel/src/body.rs

@@ -454,18 +454,15 @@ const MAX_REFUSAL_PROBES: usize = 20_000;
 
 impl Refusal {
     /// The refusal of `record` for `error`, with the face SMLib refuses on its own.
-    pub(crate) fn of(record: &Brep, error: &solidcraft_smlib::Error) -> Refusal {
+    fn of(record: &Brep, error: &solidcraft_smlib::Error) -> Refusal {
         if let solidcraft_smlib::Error::Internal(why) = error {
             return Refusal { face: None, surface: None, why: why.clone(), internal: true };
         }
         let _span = solidcraft_profile::span("kernel", "smlib_refusal_face");
-        // It is kept with the body for every later reader: a stopped job's probes must not decide it.
-        let face = solidcraft_smlib::stop::unstoppable(|| {
-            let alone = |f: usize| crate::surfaces::Parts::of(record, &[(f, false)]).and_then(|p| p.canonical()).map(|c| c.brep);
-            (record.faces.len() <= MAX_REFUSAL_PROBES)
-                .then(|| (0..record.faces.len()).find(|&f| alone(f).is_ok_and(|r| solidcraft_smlib::Brep::from_record(&r, true).is_err())))
-                .flatten()
-        });
+        let alone = |f: usize| crate::surfaces::Parts::of(record, &[(f, false)]).and_then(|p| p.canonical()).map(|c| c.brep);
+        let face = (record.faces.len() <= MAX_REFUSAL_PROBES)
+            .then(|| (0..record.faces.len()).find(|&f| alone(f).is_ok_and(|r| solidcraft_smlib::Brep::from_record(&r, true).is_err())))
+            .flatten();
         let surface = face.and_then(|f| record.faces.get(f)).map(|f| SurfaceKind::of(&f.surface));
         Refusal { face, surface, why: error.to_string(), internal: false }
     }
@@ -548,10 +545,7 @@ impl Body {
     pub fn smlib(&self) -> Result<&solidcraft_smlib::Brep> {
         self.require_brep("an SMLib operation")?;
         self.smlib
-            .get_or_init(|| {
-                solidcraft_smlib::stop::unstoppable(|| solidcraft_smlib::Brep::from_record(&self.record, true))
-                    .map_err(|e| Refusal::of(&self.record, &e))
-            })
+            .get_or_init(|| solidcraft_smlib::Brep::from_record(&self.record, true).map_err(|e| Refusal::of(&self.record, &e)))
             .as_ref()
             .map_err(
                 |r| if r.internal { KernelError::Internal(format!("SMLib: {}", r.why)) } else { KernelError::Failed(format!("SMLib: {}", r.why)) },

crates/kernel/src/build.rs

@@ -68,20 +68,32 @@ pub(crate) fn frame_ok(plane: &Plane) -> bool {
 /// Extrude each region from `start` to `end` along the plane normal (offsets in mm, `end > start`).
 pub fn extrude(plane: &Plane, regions: &[Region2], start: f64, end: f64) -> Result<Vec<Body>> {
     let _span = solidcraft_profile::span("kernel", "extrude");
-    extrude_with(plane, regions, start, end, false)
+    extrude_with(plane, regions, start, end, None)
 }
 
 /// [`extrude`] with each run of profile lines that continue one another in a straight line (a side
 /// drawn in two pieces, a mirrored half meeting its mirror image) swept into one side face over
-/// all its pieces, rather than coplanar faces with an edge between them (#1788). The side's
+/// all its pieces, rather than coplanar faces with an edge between them (#1788), and each run of
+/// free-form segments (conics, Béziers) that `one_curve` says are pieces of one curve (an
+/// ellipse's four quarters, a spline's spans) swept as that one curve into one wall. The side's
 /// history lists every piece under it. For the Extrude feature; other builders (sheet metal's
 /// flat pattern, tools) keep a face per segment.
-pub fn extrude_whole_sides(plane: &Plane, regions: &[Region2], start: f64, end: f64) -> Result<Vec<Body>> {
+pub fn extrude_whole_sides(plane: &Plane, regions: &[Region2], start: f64, end: f64, one_curve: &dyn Fn(&Seg2, &Seg2) -> bool) -> Result<Vec<Body>> {
     let _span = solidcraft_profile::span("kernel", "extrude_whole_sides");
-    extrude_with(plane, regions, start, end, true)
+    extrude_with(plane, regions, start, end, Some(one_curve))
 }
 
-fn extrude_with(plane: &Plane, regions: &[Region2], start: f64, end: f64, whole_sides: bool) -> Result<Vec<Body>> {
+/// The degree of a free-form segment (a conic or a Bézier), none for a line or an arc.
+fn free_form_degree(s: &Seg2) -> Option<u8> {
+    match *s {
+        Seg2::Conic { .. } => Some(2),
+        Seg2::Cubic { .. } => Some(3),
+        Seg2::Bezier { n, .. } => Some(n),
+        Seg2::Line { .. } | Seg2::Arc { .. } => None,
+    }
+}
+
+fn extrude_with(plane: &Plane, regions: &[Region2], start: f64, end: f64, one_curve: Option<&dyn Fn(&Seg2, &Seg2) -> bool>) -> Result<Vec<Body>> {
     if !frame_ok(plane) {
         return Err(KernelError::Invalid("extrude frame is not finite and orthonormal".into()));
     }
@@ -98,8 +110,26 @@ fn extrude_with(plane: &Plane, regions: &[Region2], start: f64, end: f64, whole_
         .map(|r| {
             region_ok(r)?;
             let pieces = oriented(r)?;
-            let numbered = if whole_sides { pieces.map_loops(|l| l.merged_lines(continues_straight)) } else { pieces.clone() };
-            crate::smlib_sweeps::extrude(plane, &crate::smlib_sweeps::region_pieces(&numbered, &pieces), Some(r), lo, hi - lo, 1.0, None)
+            let Some(one_curve) = one_curve else {
+                return crate::smlib_sweeps::extrude(plane, &crate::smlib_sweeps::region_pieces(&pieces, &pieces), Some(r), lo, hi - lo, 1.0, None);
+            };
+            // Pieces of one curve: free-form segments of one degree that the caller says are one
+            // curve. Each loop starts where such a run starts, so no run wraps round its end.
+            let joins = |s: &Seg2, t: &Seg2| free_form_degree(s).is_some_and(|d| free_form_degree(t) == Some(d)) && one_curve(s, t);
+            let numbered = pieces.map_loops(|l| l.merged_lines(continues_straight).starting_a_run(joins));
+            let mut swept = crate::smlib_sweeps::region_pieces(&numbered, &pieces);
+            let mut k = 0;
+            for l in numbered.loops() {
+                for i in 1..l.lp.segs.len() {
+                    if let (Some(s), Some(t)) = (l.lp.segs.get(i - 1), l.lp.segs.get(i))
+                        && let Some(x) = swept.get_mut(k + i)
+                    {
+                        x.joins_previous = joins(s, t);
+                    }
+                }
+                k += l.lp.segs.len();
+            }
+            crate::smlib_sweeps::extrude(plane, &swept, Some(r), lo, hi - lo, 1.0, None)
         })
         .collect()
 }

crates/kernel/src/history_tests.rs

@@ -256,7 +256,7 @@ fn collinear_profile_lines_extrude_into_one_side_face() {
     let region = Region2 { outer: Loop2::polygon(&pts), holes: vec![] };
     // Plain `extrude` keeps a face per segment (sheet metal's flat pattern relies on it).
     assert_eq!(crate::extrude(&Plane::XY, std::slice::from_ref(&region), 0.0, 5.0).unwrap()[0].face_count(), 7);
-    let body = crate::extrude_whole_sides(&Plane::XY, &[region], 0.0, 5.0).unwrap().pop().unwrap();
+    let body = crate::extrude_whole_sides(&Plane::XY, &[region], 0.0, 5.0, &|_, _| false).unwrap().pop().unwrap();
     assert_eq!(body.face_count(), 6, "a box has six faces");
     assert!((crate::measure(&body).unwrap().volume - 1000.0).abs() < 1e-9);
     let h = body.history().unwrap();
@@ -276,10 +276,75 @@ fn collinear_profile_lines_extrude_into_one_side_face() {
     );
     // A corner is not a straight run: an L-shaped step keeps its faces.
     let step = [(0.0, 0.0), (10.0, 0.0), (10.0, 5.0), (20.0, 5.0), (20.0, 10.0), (0.0, 10.0)].map(|(x, y)| Vec2::new(x, y));
-    let body = crate::extrude_whole_sides(&Plane::XY, &[Region2 { outer: Loop2::polygon(&step), holes: vec![] }], 0.0, 5.0).unwrap().pop().unwrap();
+    let body = crate::extrude_whole_sides(&Plane::XY, &[Region2 { outer: Loop2::polygon(&step), holes: vec![] }], 0.0, 5.0, &|_, _| false)
+        .unwrap()
+        .pop()
+        .unwrap();
     assert_eq!(body.face_count(), 8);
 }
 
+/// The pieces of one ellipse (four conic quarters) or one spline (its cubic spans) that the
+/// caller calls one curve sweep into one wall generated by all of them, the same solid as a face
+/// per piece: the ellipse's volume is π a b h. Pieces not called one curve keep a face each.
+#[test]
+fn pieces_of_one_curve_extrude_into_one_wall() {
+    use solidcore_record::{Loop2, Plane, Region2, Seg2, Vec2};
+    let v = Vec2::new;
+    let (c, u, w) = (v(1.0, 2.0), v(10.0, 0.0), v(0.0, 5.0));
+    let corners = [c + u, c + w, c - u, c - w];
+    let ellipse: Vec<Seg2> = (0..4)
+        .map(|i| {
+            let (a, b) = (corners[i], corners[(i + 1) % 4]);
+            Seg2::Conic { a, apex: a + b - c, b, w: std::f64::consts::FRAC_1_SQRT_2 }
+        })
+        .collect();
+    // A cubic spline's three spans (C2 at its joints, on unequal knot spans), closed by lines.
+    let spline = vec![
+        Seg2::Cubic {
+            p0: v(0.0, 0.0),
+            p1: v(3.478154619431441, -1.9606112245268097),
+            p2: v(6.956309238862882, -3.921222449053619),
+            p3: v(10.0, -3.0),
+        },
+        Seg2::Cubic {
+            p0: v(10.0, -3.0),
+            p1: v(13.55861013478923, -1.9229288384169465),
+            p2: v(16.52332013301099, 3.0935296384274267),
+            p3: v(20.0, 4.0),
+        },
+        Seg2::Cubic {
+            p0: v(20.0, 4.0),
+            p1: v(23.067612954017893, 4.799814860722723),
+            p2: v(26.533806477008945, 2.3999074303613614),
+            p3: v(30.0, 0.0),
+        },
+        Seg2::Line { a: v(30.0, 0.0), b: v(30.0, 20.0) },
+        Seg2::Line { a: v(30.0, 20.0), b: v(0.0, 20.0) },
+        Seg2::Line { a: v(0.0, 20.0), b: v(0.0, 0.0) },
+    ];
+    for (segs, walls, pieces) in [(ellipse, 1, 4), (spline, 4, 3)] {
+        let region = Region2 { outer: Loop2 { segs }, holes: vec![] };
+        let apart = crate::extrude_whole_sides(&Plane::XY, std::slice::from_ref(&region), 0.0, 7.0, &|_, _| false).unwrap().remove(0);
+        let body = crate::extrude_whole_sides(&Plane::XY, std::slice::from_ref(&region), 0.0, 7.0, &|_, _| true).unwrap().remove(0);
+        assert_eq!(apart.face_count(), 2 + walls - 1 + pieces, "a face per piece when they are not one curve");
+        assert_eq!(body.face_count(), 2 + walls, "one wall over the curve's pieces");
+        let (joined, each) = (crate::measure(&body).unwrap().volume, crate::measure(&apart).unwrap().volume);
+        assert!((joined - each).abs() < 1e-9 * each, "{joined} vs {each}");
+        let h = body.history().unwrap();
+        h.check(&body, &[]).unwrap();
+        let curved: Vec<Vec<FaceOrigin>> = h.faces.iter().map(|f| f.origins.clone()).filter(|o| o.len() > 1).collect();
+        assert_eq!(curved.len(), 1, "{:?}", h.faces);
+        let mut segments: Vec<usize> =
+            curved[0].iter().filter_map(|o| if let FaceOrigin::Profile { segment } = o { Some(*segment) } else { None }).collect();
+        segments.sort();
+        assert_eq!(segments, (0..pieces).collect::<Vec<_>>(), "the wall is generated by every piece of the curve");
+        if walls == 1 {
+            let exact = std::f64::consts::PI * 10.0 * 5.0 * 7.0;
+            assert!((joined - exact).abs() < 1e-6 * exact, "{joined} vs π a b h = {exact}");
+        }
+    }
+}
+
 /// A tapered extrude joins a side drawn in collinear pieces as the straight extrude does
 /// (#1788): one sloped face generated by both pieces, and the same solid as a side in one piece.
 #[test]

crates/kernel/src/issue_1080_tests.rs

@@ -88,7 +88,7 @@ fn chamfers_crossing_each_other_are_refused() {
     too_large(crate::chamfer(&rib, &edges, 3.0));
     too_large(crate::fillet(&rib, &edges, 3.0));
     assert_eq!(crate::chamfer_max(&rib, &edges, 3.0).unwrap().map(|x| x.0), Some(2.0));
-    assert_eq!(crate::fillet_max(&rib, &edges, 3.0).unwrap().map(|x| x.0), Some(2.0));
+    assert_eq!(crate::fillet_max(&rib, &edges, 3.0, crate::FilletTurn::Mitre).unwrap().map(|x| x.0), Some(2.0));
     // Below half the width both build.
     let b = crate::chamfer(&rib, &edges, 1.5).unwrap();
     assert!((b.volume_at(0.01).unwrap() - (3200.0 - 2.0 * 0.5 * 1.5 * 1.5 * 40.0)).abs() < 1e-6);

crates/kernel/src/lib.rs

@@ -156,7 +156,7 @@ mod validity;
 pub mod watch;
 
 pub use blend::{
-    ChamferSide, SETBACK_AT_LEAST, blend_edges, chamfer, chamfer_max, chamfer_sides, fillet, fillet_each, fillet_g2, fillet_g2_corners,
+    ChamferSide, FilletTurn, SETBACK_AT_LEAST, blend_edges, chamfer, chamfer_max, chamfer_sides, fillet, fillet_each, fillet_g2, fillet_g2_corners,
     fillet_g2_with_g2_corners, fillet_least_setback, fillet_max, fillet_max_each, fillet_removing, fillet_setback, largest_fit_note,
     names_largest_fit, tangent_chain, with_fit_note,
 };
@@ -215,8 +215,6 @@ pub use prism_curve::{PlanarPiece, PlanarSpline};
 pub use prism_measure::{PrismSection, certified_prism_equivalent, certified_prism_section};
 pub use repair::{Hole, RebuiltFace, RefusedFace, RepairOptions, RepairReport, SewnGap, repair};
 pub use sew::{EdgeSpec, FaceSpec, SurfSpec, sew, sew_touching};
-pub use solidcraft_smlib::hold_a_kernel;
-pub use solidcraft_smlib::stop::Stop;
 pub use solidcraft_smlib::trace as smlib_trace;
 pub use splitface::{SplitTool, split_body, split_faces, split_faces_with_map};
 pub use step::step_export;

crates/kernel/src/numbered.rs

@@ -152,6 +152,19 @@ impl NumberedLoop {
         out
     }
 
+    /// The same loop started at a segment `joins` does not join to the one before it, so no run of
+    /// joined segments wraps round the loop's end (as it is when every segment joins the next).
+    pub(crate) fn starting_a_run(&self, joins: impl Fn(&Seg2, &Seg2) -> bool) -> NumberedLoop {
+        let segs = &self.lp.segs;
+        let n = segs.len();
+        let joined = |i: usize| matches!((segs.get((i + n - 1) % n), segs.get(i)), (Some(s), Some(t)) if joins(s, t));
+        let mut out = self.clone();
+        if let Some(k) = (0..n).find(|&i| !joined(i)) {
+            out.rotate_left(k);
+        }
+        out
+    }
+
     /// Split segment `k` in half, both halves over what it ran over.
     fn split_half(&mut self, k: usize) {
         if k >= self.lp.segs.len() || k >= self.from.len() {

crates/kernel/src/par.rs

@@ -28,10 +28,9 @@ fn pool() -> Option<&'static rayon::ThreadPool> {
 /// thread. Waking the pool's workers costs tens of microseconds, so callers ask for it only
 /// when the items carry more work than that (decided from the work, not the item count).
 pub(crate) fn map<T: Sync, R: Send>(what: &'static str, items: &[T], parallel: bool, f: impl Fn(&T) -> Result<R> + Sync) -> Vec<Result<R>> {
-    // The workers run under the caller's validation mode (`crate::validation`) and stop token.
+    // The workers run under the caller's validation mode (`crate::validation`).
     let scope = crate::validation::current();
-    let stop = solidcraft_smlib::stop::current();
-    let one = |item: &T| solidcraft_smlib::stop::scoped(stop.clone(), || crate::validation::within(scope.clone(), || guard(what, || f(item))));
+    let one = |item: &T| crate::validation::within(scope.clone(), || guard(what, || f(item)));
     // The browser build has no worker pool: everything runs on the calling thread.
     #[cfg(target_arch = "wasm32")]
     let _ = parallel;
@@ -88,8 +87,7 @@ pub fn map_with_local_pools<T: Sync, R: Send>(items: &[T], max_threads: usize, f
             }
             let pool = cell.get().ok_or_else(|| crate::KernelError::Failed("missing mesh worker".into()))?;
             let scope = crate::validation::current();
-            let stop = solidcraft_smlib::stop::current();
-            pool.install(|| solidcraft_smlib::stop::scoped(stop, || crate::validation::within(scope, || guard("mesh worker", || f(item)))))
+            pool.install(|| crate::validation::within(scope, || guard("mesh worker", || f(item))))
         })
     };
     #[cfg(target_arch = "wasm32")]
@@ -103,12 +101,9 @@ pub fn map_with_local_pools<T: Sync, R: Send>(items: &[T], max_threads: usize, f
 /// `f` over `items` as [`for_each_on_threads`] runs it, results in item order (`None` where an
 /// item panicked).
 pub fn map_on_threads<T: Sync, R: Send>(items: &[T], max_threads: usize, f: impl Fn(&T) -> R + Sync) -> Vec<Option<R>> {
-    // The threads run under the caller's validation mode (`crate::validation`) and stop token.
+    // The threads run under the caller's validation mode (`crate::validation`).
     let scope = crate::validation::current();
-    let stop = solidcraft_smlib::stop::current();
-    let one = |item: &T| {
-        solidcraft_smlib::stop::scoped(stop.clone(), || crate::validation::within(scope.clone(), || guard("parallel item", || Ok(f(item))).ok()))
-    };
+    let one = |item: &T| crate::validation::within(scope.clone(), || guard("parallel item", || Ok(f(item))).ok());
     #[cfg(not(target_arch = "wasm32"))]
     {
         use std::sync::atomic::{AtomicUsize, Ordering};

crates/kernel/src/planar_sources.rs

@@ -172,6 +172,119 @@ pub(super) fn same_support(a: &Plane, b: &Plane, at: Resolution) -> bool {
         && (a.origin - b.origin).dot(nb).abs() <= at.linear
 }
 
+/// A source a face on its plane can take: the plane it names (for a shell's inner role, the
+/// source's plane moved in and turned round), the source, and whether it is that inner role.
+#[derive(Clone, Copy, Debug, PartialEq)]
+struct Candidate<'a> {
+    plane: Plane,
+    source: &'a FaceSource,
+    inner: bool,
+}
+
+/// What a mapping's inputs say of one plane of its result.
+#[derive(Debug, PartialEq)]
+enum Support<'a> {
+    /// A face without a role, or a competing tool face, lies on the plane.
+    Blocked,
+    /// Every candidate on the plane is one source, plane and role: the pieces of one logical face.
+    Source(Candidate<'a>),
+    /// No candidate lies on the plane, or candidates of distinct identities do.
+    Unnamed,
+}
+
+/// Planes partitioned into supports, in their order: a plane starts a group unless it is one
+/// support (`same_support`) with the first plane of an earlier group, which it then joins. Returns
+/// each plane's group and each group's first plane; `looked` counts the planes looked at.
+fn group_supports(planes: &[Plane], at: Resolution, looked: &mut usize) -> (Vec<usize>, Vec<usize>) {
+    let index = PlaneIndex::new(planes.iter(), at);
+    let mut group: Vec<Option<usize>> = vec![None; planes.len()];
+    let mut first = Vec::new();
+    for (i, plane) in planes.iter().enumerate() {
+        if group.get(i).is_some_and(Option::is_some) {
+            continue;
+        }
+        let g = first.len();
+        first.push(i);
+        let near = index.near(plane);
+        *looked += near.len();
+        for j in near {
+            if let Some(slot @ None) = group.get_mut(j)
+                && (j == i || planes.get(j).is_some_and(|other| same_support(plane, other, at)))
+            {
+                *slot = Some(g);
+            }
+        }
+    }
+    (group.into_iter().map(|g| g.unwrap_or(usize::MAX)).collect(), first)
+}
+
+/// The candidates and blocking planes of a mapping grouped by support once, so each result face
+/// looks up its plane's few groups instead of every candidate on that plane: with many coplanar
+/// faces the work grows with the faces plus the candidates, not with their product.
+struct SupportDecisions<'a> {
+    /// Each candidate group's first plane, and its decision: its first candidate, or none when
+    /// the group holds candidates of distinct identities.
+    groups: Vec<(Plane, Option<Candidate<'a>>)>,
+    group_index: PlaneIndex,
+    /// The first plane of each group of the faces without a role and the competing tool faces.
+    blocking: Vec<Plane>,
+    blocking_index: PlaneIndex,
+    at: Resolution,
+    /// The planes looked at, building the groups and deciding faces.
+    looked: usize,
+}
+
+impl<'a> SupportDecisions<'a> {
+    /// `candidates` in the order that decides between them.
+    fn new(candidates: &[Candidate<'a>], unknown: &[Plane], competing: &[Plane], at: Resolution) -> Self {
+        let mut looked = 0;
+        let planes: Vec<Plane> = candidates.iter().map(|c| c.plane).collect();
+        let (group, first) = group_supports(&planes, at, &mut looked);
+        let mut groups: Vec<(Plane, Option<Candidate<'a>>)> = first.iter().filter_map(|&i| candidates.get(i)).map(|c| (c.plane, Some(*c))).collect();
+        for (candidate, g) in candidates.iter().zip(&group) {
+            if let Some((_, decision)) = groups.get_mut(*g)
+                && decision.is_some_and(|d| d != *candidate)
+            {
+                *decision = None;
+            }
+        }
+        let group_index = PlaneIndex::new(groups.iter().map(|g| &g.0), at);
+        let all_blocking: Vec<Plane> = unknown.iter().chain(competing).copied().collect();
+        let (_, first) = group_supports(&all_blocking, at, &mut looked);
+        let blocking: Vec<Plane> = first.iter().filter_map(|&i| all_blocking.get(i).copied()).collect();
+        let blocking_index = PlaneIndex::new(blocking.iter(), at);
+        SupportDecisions { groups, group_index, blocking, blocking_index, at, looked }
+    }
+
+    /// What the inputs say of a face on `actual`.
+    fn at(&mut self, actual: &Plane) -> Support<'a> {
+        let at = self.at;
+        let near = self.blocking_index.near(actual);
+        self.looked += near.len();
+        if near.into_iter().any(|i| self.blocking.get(i).is_some_and(|plane| same_support(plane, actual, at))) {
+            return Support::Blocked;
+        }
+        let mut near = self.group_index.near(actual);
+        self.looked += near.len();
+        // Groups are numbered in the candidates' order, so the first matching group's first
+        // candidate is the first candidate on the plane.
+        near.sort_unstable();
+        let mut chosen: Option<Candidate<'a>> = None;
+        for (plane, decision) in near.into_iter().filter_map(|g| self.groups.get(g)) {
+            if !same_support(plane, actual, at) {
+                continue;
+            }
+            match (chosen, decision) {
+                (_, None) => return Support::Unnamed,
+                (None, Some(d)) => chosen = Some(*d),
+                (Some(c), Some(d)) if c != *d => return Support::Unnamed,
+                _ => {}
+            }
+        }
+        chosen.map_or(Support::Unnamed, Support::Source)
+    }
+}
+
 fn base_plane(source: &FaceSource, actual: &Plane) -> Option<Plane> {
     match source {
         FaceSource::CertifiedExtrudeSide { plane: Some(p), .. }
@@ -339,98 +452,40 @@ impl Body {
                     unknown_supports.push(actual);
                     continue;
                 }
-                let Some(cost) = descriptor_cost(source) else {
+                if descriptor_cost(source).is_none() {
                     unknown_supports.push(actual);
                     continue;
-                };
-                candidates.push((plane, source, false, cost));
+                }
+                candidates.push(Candidate { plane, source, inner: false });
                 if let Some(t) = shell {
                     let inner = Plane::new(plane.origin - plane.normal() * t, plane.x, -plane.y)
                         .ok_or_else(|| KernelError::Invalid("invalid shell inner source plane".into()))?;
-                    candidates.push((inner, source, true, cost));
+                    candidates.push(Candidate { plane: inner, source, inner: true });
                 }
             }
             // The candidates are taken in the order of their normal's x: where several match one
             // face, the first decides which the rest are compared with.
-            candidates.sort_by(|a, b| a.0.normal().x.total_cmp(&b.0.normal().x));
-            let unknown_index = PlaneIndex::new(unknown_supports.iter(), at);
-            let competing_index = PlaneIndex::new(competing.iter(), at);
-            let candidate_index = PlaneIndex::new(candidates.iter().map(|c| &c.0), at);
-            let mut metadata = 2_000_000usize;
-            let mut identity_bytes = 16_000_000usize;
+            candidates.sort_by(|a, b| a.plane.normal().x.total_cmp(&b.plane.normal().x));
+            let mut decide = SupportDecisions::new(&candidates, &unknown_supports, &competing, at);
             let mut result = Vec::new();
             for (index, actual) in actual_planes(&self)?.into_iter().enumerate() {
-                let mut found = None;
-                if let Some(actual) = actual {
-                    let on = |planes: &[Plane], index: &PlaneIndex| {
-                        index.near(&actual).into_iter().any(|i| planes.get(i).is_some_and(|plane| same_support(plane, &actual, at)))
-                    };
-                    let blocked = on(&unknown_supports, &unknown_index) || on(&competing, &competing_index);
-                    if blocked {
-                        let existing = self
-                            .face_sources()
-                            .and_then(|sources| sources.get(index))
-                            .and_then(|s| s.as_ref())
-                            .filter(|s| (boolean || self.face_was_coalesced(index)) && !boolean_source(s, constructed));
-                        let keep = existing.and_then(|s| {
-                            descriptor_cost(s).and_then(|cost| {
-                                metadata.checked_sub(cost).map(|remaining| {
-                                    metadata = remaining;
-                                    s.clone()
-                                })
-                            })
-                        });
-                        result.push(keep);
-                        continue;
-                    }
-                    let mut chosen: Option<(Plane, &FaceSource, bool, usize)> = None;
-                    let mut near = candidate_index.near(&actual);
-                    near.sort_unstable();
-                    for (plane, source, inner, cost) in near.into_iter().filter_map(|i| candidates.get(i)) {
-                        if same_support(plane, &actual, at) {
-                            if let Some((previous_plane, previous_source, previous_inner, _)) = chosen {
-                                let Some(remaining) = identity_bytes.checked_sub(*cost) else {
-                                    chosen = None;
-                                    break;
-                                };
-                                identity_bytes = remaining;
-                                // Several current pieces of one exact source are one
-                                // logical face; distinct source identities remain ambiguous.
-                                if previous_plane != *plane || previous_source != *source || previous_inner != *inner {
-                                    chosen = None;
-                                    break;
-                                }
-                            } else {
-                                chosen = Some((*plane, *source, *inner, *cost));
-                            }
-                        }
-                    }
-                    if let Some((plane, source, inner, cost)) = chosen
-                        && let Some(remaining) = metadata.checked_sub(cost)
-                    {
-                        metadata = remaining;
-                        found = Some(if shell.is_some() {
-                            FaceSource::ShellPlanar { producer: None, source: Box::new(source.clone()), inner, plane }
-                        } else {
-                            source.clone()
-                        });
-                    }
-                }
-                if found.is_none() && (boolean || self.face_was_coalesced(index)) {
-                    found = self
-                        .face_sources()
+                // A face no candidate names keeps what it had, where an operation could have left
+                // it a source no role describes.
+                let existing = || {
+                    self.face_sources()
                         .and_then(|sources| sources.get(index))
                         .and_then(|s| s.as_ref())
-                        .filter(|s| !boolean_source(s, constructed))
-                        .and_then(|s| {
-                            descriptor_cost(s).and_then(|cost| {
-                                metadata.checked_sub(cost).map(|remaining| {
-                                    metadata = remaining;
-                                    s.clone()
-                                })
-                            })
-                        });
-                }
+                        .filter(|s| (boolean || self.face_was_coalesced(index)) && !boolean_source(s, constructed) && descriptor_cost(s).is_some())
+                        .cloned()
+                };
+                let found = match actual.map(|actual| decide.at(&actual)) {
+                    Some(Support::Source(Candidate { plane, source, inner })) => Some(if shell.is_some() {
+                        FaceSource::ShellPlanar { producer: None, source: Box::new(source.clone()), inner, plane }
+                    } else {
+                        source.clone()
+                    }),
+                    Some(Support::Blocked | Support::Unnamed) | None => existing(),
+                };
                 result.push(found);
             }
             Ok(result)
@@ -574,6 +629,90 @@ mod tests {
         assert!(matches > 2 * planes.len(), "the planes meet each other, not only themselves: {matches}");
     }
 
+    /// Many faces on one plane are decided with work that grows with the faces plus the
+    /// candidates: each face looks at its plane's one group, never at every candidate on it.
+    #[test]
+    fn coplanar_faces_are_decided_by_group_in_linear_work() {
+        let body = box_solid(Vec3::ZERO, Vec3::new(1000., 1000., 10.)).unwrap();
+        let at = Resolution::of(&body);
+        let top = Plane::new(Vec3::new(0., 0., 10.), Vec3::X, Vec3::Y).unwrap();
+        let one = FaceSource::Box { producer: Some(1), axis: 2, high: true, plane: top };
+        let other = FaceSource::Box { producer: Some(2), axis: 2, high: true, plane: top };
+        for n in [100usize, 1000] {
+            // `n` pieces of one cap and `n` faces of the result on its plane, each a little moved
+            // along the plane (as a split face's pieces are).
+            let pieces: Vec<Plane> = (0..n).map(|k| Plane::new(Vec3::new(k as f64, 0., 10.), Vec3::X, Vec3::Y).unwrap()).collect();
+            let candidates: Vec<Candidate> = (0..n).map(|_| Candidate { plane: top, source: &one, inner: false }).collect();
+            let mut decide = SupportDecisions::new(&candidates, &[], &[], at);
+            for piece in &pieces {
+                assert_eq!(decide.at(piece), Support::Source(Candidate { plane: top, source: &one, inner: false }));
+            }
+            // One look per candidate to group them, one per face to find its group: a scan of
+            // every candidate per face would look n * n times.
+            assert_eq!(decide.looked, 2 * n);
+            // A second identity among the candidates leaves the plane unnamed; a face without a
+            // role on it blocks it.
+            let mut mixed = candidates.clone();
+            mixed[n / 2] = Candidate { plane: top, source: &other, inner: false };
+            assert_eq!(SupportDecisions::new(&mixed, &[], &[], at).at(&pieces[0]), Support::Unnamed);
+            let unknown = vec![top; n];
+            let mut blocked = SupportDecisions::new(&candidates, &unknown, &[], at);
+            assert!(pieces.iter().all(|piece| blocked.at(piece) == Support::Blocked));
+            assert_eq!(blocked.looked, 3 * n);
+        }
+    }
+
+    /// A plate with 300 holes whose top a comb of grooves cuts into 62 strips: every strip keeps
+    /// the top cap's source, every bottom face the bottom cap's, however many there are.
+    #[test]
+    fn many_coplanar_pieces_of_a_holed_plate_all_keep_their_cap_source() {
+        use solidcore_record::{Loop2, Region2, Vec2};
+        let holes: Vec<Loop2> =
+            (0..60).flat_map(|k| (0..5).map(move |r| Loop2::circle(Vec2::new(10. + 10. * k as f64, 5. + 10. * r as f64), 1.))).collect();
+        let outer = Loop2::polygon(&[Vec2::new(0., 0.), Vec2::new(610., 0.), Vec2::new(610., 50.), Vec2::new(0., 50.)]);
+        let region = Region2 { outer, holes };
+        let raw = crate::extrude(&Plane::XY, std::slice::from_ref(&region), 0., 10.).unwrap().remove(0);
+        let hole_ids: Vec<Vec<String>> = (0..300).map(|k| vec![format!("c{k}")]).collect();
+        let signatures: Vec<_> = raw
+            .face_sources()
+            .unwrap()
+            .iter()
+            .map(|s| matches!(s, Some(FaceSource::ExtrudeCap { .. })).then(|| (vec!["l1".to_string()], hole_ids.clone())))
+            .collect();
+        let plate = raw.with_extrude_cap_certificates(5, 3, &signatures).unwrap();
+        // A comb: 61 teeth 2 wide across the plate between the columns of holes, 2 deep.
+        let mut comb = vec![Vec2::new(-5., 55.), Vec2::new(-5., 60.), Vec2::new(615., 60.), Vec2::new(615., 55.)];
+        for k in (0..=60).rev() {
+            let x = 4. + 10. * k as f64;
+            comb.extend([Vec2::new(x + 2., 55.), Vec2::new(x + 2., -5.), Vec2::new(x, -5.), Vec2::new(x, 55.)]);
+        }
+        let comb = Region2 { outer: Loop2::polygon(&comb), holes: vec![] };
+        let tool = crate::extrude(&Plane::XY, std::slice::from_ref(&comb), 8., 12.).unwrap().remove(0);
+        let cut = crate::boolean(&plate, &tool, crate::BoolOp::Cut).unwrap().unwrap();
+        let sources = cut.face_sources().unwrap();
+        let (mut tops, mut bottoms) = (0, 0);
+        for (i, plane) in actual_planes(&cut).unwrap().into_iter().enumerate() {
+            let Some(plane) = plane else { continue };
+            let high = if plane.normal().dot(Vec3::Z) > 0.999999 && (plane.origin.z - 10.).abs() < 1e-9 {
+                true
+            } else if plane.normal().dot(Vec3::Z) < -0.999999 && plane.origin.z.abs() < 1e-9 {
+                false
+            } else {
+                continue;
+            };
+            let Some(FaceSource::CertifiedExtrudeCap { producer: 5, high: h, holes, .. }) = &sources[i] else {
+                panic!("face {i} on the {} cap lost its source: {:?}", if high { "top" } else { "bottom" }, sources[i]);
+            };
+            assert_eq!((*h, holes.len()), (high, 300));
+            if high {
+                tops += 1;
+            } else {
+                bottoms += 1;
+            }
+        }
+        assert_eq!((tops, bottoms), (62, 1));
+    }
+
     #[test]
     fn rounded_shell_planar_roles_are_exact_distinct_and_transformable() {
         for (width, thickness) in [(80., 2.), (100., 3.)] {

crates/kernel/src/smlib_sweeps.rs

@@ -31,11 +31,17 @@ pub(crate) struct Piece {
     /// The segment as drawn that names it: itself, or for collinear lines joined into one, the
     /// first of them.
     pub drawn: Seg2,
+    /// It carries on the piece before it as one curve (pieces of one ellipse or spline): SMLib
+    /// gets the run as one B-spline and sweeps one wall over it.
+    pub joins_previous: bool,
 }
 
 /// The segments of `loops` as pieces, loop after loop.
 pub(crate) fn pieces<'a>(loops: impl IntoIterator<Item = &'a NumberedLoop>) -> Vec<Piece> {
-    loops.into_iter().flat_map(|l| l.lp.segs.iter().enumerate().map(|(i, s)| Piece { seg: *s, numbers: l.numbers(i).to_vec(), drawn: *s })).collect()
+    loops
+        .into_iter()
+        .flat_map(|l| l.lp.segs.iter().enumerate().map(|(i, s)| Piece { seg: *s, numbers: l.numbers(i).to_vec(), drawn: *s, joins_previous: false }))
+        .collect()
 }
 
 /// The pieces of `joined` (`drawn` with collinear lines joined): outer loop, then holes, each
@@ -145,8 +151,70 @@ mod imp {
         })
     }
 
+    /// The pieces as SMLib's curves: one each, but one B-spline for each run of pieces that join
+    /// the one before them ([`Piece::joins_previous`]).
     fn curves(plane: &Plane, pieces: &[Piece]) -> Result<Vec<Curve>> {
-        pieces.iter().map(|x| curve(plane, &x.seg)).collect()
+        let mut out = Vec::new();
+        let mut run = Vec::new();
+        for x in pieces {
+            if !x.joins_previous && !run.is_empty() {
+                out.push(joined(std::mem::take(&mut run))?);
+            }
+            run.push(curve(plane, &x.seg)?);
+        }
+        if !run.is_empty() {
+            out.push(joined(run)?);
+        }
+        Ok(out)
+    }
+
+    /// Bézier curves of one degree, each starting where the one before ends, as the one B-spline
+    /// they are, exactly: their control points in a row (each joint once) on knots repeated the
+    /// degree times at each joint. A rational piece's weights are scaled (which leaves it the same
+    /// curve) to meet the weight the piece before ends with. Each piece's knot span is as long as
+    /// keeps the speed through the joint the same on both sides, so pieces meeting tangentially
+    /// (the pieces of one ellipse or spline) join with a continuous first derivative: SMLib makes
+    /// one wall over a curve that is, and splits it where the derivative jumps.
+    fn joined(run: Vec<Curve>) -> Result<Curve> {
+        if run.len() == 1 {
+            return run.into_iter().next().ok_or_else(|| KernelError::Invalid("an empty run of curves".into()));
+        }
+        let not_one = || KernelError::Invalid("the pieces of one curve are not Béziers of one degree".into());
+        let xyz = |q: &[f64; 4]| Vec3::new(q[0], q[1], q[2]);
+        let mut degree = None;
+        let mut points: Vec<[f64; 4]> = Vec::new();
+        let mut knots = Vec::new();
+        // The knot at the last joint, and the length of the span before it.
+        let (mut at, mut span) = (0.0, 1.0);
+        for c in &run {
+            let Curve::Nurbs { degree: d, points: ps, .. } = c else { return Err(not_one()) };
+            if degree.is_some_and(|p| p != *d) || ps.len() != d + 1 || *d == 0 {
+                return Err(not_one());
+            }
+            degree = Some(*d);
+            let (Some(first), Some(second)) = (ps.first(), ps.get(1)) else { return Err(not_one()) };
+            let (Some(last), Some(before)) = (points.last(), points.len().checked_sub(2).and_then(|i| points.get(i))) else {
+                points.extend(ps.iter().copied());
+                knots.extend(std::iter::repeat_n(0.0, d + 1));
+                continue;
+            };
+            let scale = last[3] / first[3];
+            if !(scale.is_finite() && scale > 0.0) {
+                return Err(not_one());
+            }
+            // The derivative of a rational Bézier on a span of length h at its end is
+            // d (w[d-1] / w[d]) (P[d] - P[d-1]) / h, at its start d (w[1] / w[0]) (P[1] - P[0]) / h.
+            let ending = (xyz(last) - xyz(before)) * (before[3] / last[3]) * (1.0 / span);
+            let starting = (xyz(second) - xyz(first)) * (second[3] / first[3]);
+            let next = starting.len() / ending.len();
+            at += span;
+            span = if next.is_finite() && next > 0.0 { next } else { 1.0 };
+            points.extend(ps.iter().skip(1).map(|q| [q[0], q[1], q[2], q[3] * scale]));
+            knots.extend(std::iter::repeat_n(at, *d));
+        }
+        let degree = degree.ok_or_else(not_one)?;
+        knots.extend(std::iter::repeat_n(at + span, degree + 1));
+        Ok(Curve::Nurbs { degree, points, knots })
     }
 
     /// A chain of sketch segments on `plane` as SMLib's curves, one each, exactly (lines, arcs,
@@ -564,11 +632,26 @@ mod imp {
                     };
                     crate::FaceSource::ExtrudeSide { segment: x.drawn, plane, coalesced: false }
                 }),
+                // The one wall over a whole run of pieces of one curve: named by its first piece.
+                Role::Wall(set) if run_starts(pieces, set).is_some() => run_starts(pieces, set)
+                    .and_then(|i| pieces.get(i))
+                    .map(|x| crate::FaceSource::ExtrudeSide { segment: x.drawn, plane: None, coalesced: false }),
                 _ => None,
             })
             .collect()
     }
 
+    /// The first piece of the run of joined pieces `set` is exactly (all of it, and nothing else).
+    fn run_starts(pieces: &[Piece], set: &BTreeSet<usize>) -> Option<usize> {
+        let (&first, &last) = (set.first()?, set.last()?);
+        let run = pieces.get(first..=last)?;
+        let whole = last - first + 1 == set.len()
+            && run.first().is_some_and(|x| !x.joins_previous)
+            && run.iter().skip(1).all(|x| x.joins_previous)
+            && pieces.get(last + 1).is_none_or(|x| !x.joins_previous);
+        (set.len() > 1 && whole).then_some(first)
+    }
+
     fn numbered_segments(r: &Region2) -> usize {
         r.outer.segs.len() + r.holes.iter().map(|h| h.segs.len()).sum::<usize>()
     }
@@ -595,7 +678,7 @@ mod imp {
         let walls: Vec<Piece> = pieces
             .iter()
             .filter(|x| [0.0, 0.5, 1.0].iter().any(|t| off_axis(plane.to_world(x.seg.point_at(*t)))))
-            .map(|x| Piece { seg: x.seg, numbers: x.numbers.clone(), drawn: x.drawn })
+            .map(|x| Piece { seg: x.seg, numbers: x.numbers.clone(), drawn: x.drawn, joins_previous: false })
             .collect();
         let about = |q: Vec3, a: f64| origin + turned(q - origin, k, a);
         let full = turn >= std::f64::consts::TAU - 1e-9;
@@ -1535,7 +1618,7 @@ mod imp {
                         all.extend(q.numbers.iter().copied());
                     }
                 }
-                Piece { seg: x.seg, numbers: all.into_iter().collect(), drawn: x.drawn }
+                Piece { seg: x.seg, numbers: all.into_iter().collect(), drawn: x.drawn, joins_previous: false }
             })
             .collect();
         let roles = roles(&body, start, Some(&last.0), &seeds(start, &columns, |q| q), &[], false)?;

crates/kernel/src/tests.rs

@@ -331,14 +331,14 @@ fn fillet_max_finds_the_largest_radius_that_works() {
     let b = box_solid(Vec3::new(14.0, 0.0, 0.0), Vec3::new(28.0, 6.0, 10.0)).unwrap();
     let mids = [Vec3::new(14.0, 0.0, 5.0), Vec3::new(28.0, 0.0, 5.0), Vec3::new(14.0, 6.0, 5.0), Vec3::new(28.0, 6.0, 5.0)];
     assert!(too_large(&b, &mids, 3.5));
-    let (r, body) = fillet_max(&b, &mids, 3.5).unwrap().unwrap();
+    let (r, body) = fillet_max(&b, &mids, 3.5, FilletTurn::Mitre).unwrap().unwrap();
     assert_eq!(r, 3.0);
     assert!(rel(measure(&body).unwrap().volume, 840.0 - (4.0 - PI) * 90.0) < 2e-4);
     // No edge there: the fillet's own error, not a smaller radius (only a refusal as too large
     // narrows the search).
     let e = fillet(&b, &[Vec3::new(500.0, 0.0, 5.0)], 1.0).unwrap_err();
     assert!(!matches!(e, KernelError::TooLarge(_)), "{e}");
-    assert_eq!(fillet_max(&b, &[Vec3::new(500.0, 0.0, 5.0)], 1.0).unwrap_err().to_string(), e.to_string());
+    assert_eq!(fillet_max(&b, &[Vec3::new(500.0, 0.0, 5.0)], 1.0, FilletTurn::Mitre).unwrap_err().to_string(), e.to_string());
 }
 
 /// Edges that share no face get their own largest radius: a 2 mm fin's top edge takes at most
@@ -360,7 +360,7 @@ fn fillet_max_each_reduces_only_where_the_radius_does_not_fit() {
     // at its edge less the quarter disc about (17, 26), inside the fin (x >= 19): 2 x 4 less the
     // disc's part, in closed form; the corner's round (1 − π/4)·16 along 20.
     let both = fillet(&body, &edges, 4.0).unwrap();
-    let (radii, b) = fillet_max_each(&body, &edges, 4.0).unwrap().unwrap();
+    let (radii, b) = fillet_max_each(&body, &edges, 4.0, FilletTurn::Mitre).unwrap().unwrap();
     assert_eq!(radii, vec![4.0, 4.0], "{radii:?}");
     assert!(b.validity().is_empty(), "{:?}", b.validity());
     let disc = |a: f64| 0.5 * (a * (16.0 - a * a).max(0.0).sqrt() + 16.0 * (a / 4.0).asin());
@@ -371,7 +371,7 @@ fn fillet_max_each_reduces_only_where_the_radius_does_not_fit() {
     // The post's four edges limit each other: one radius, as `fillet_max`.
     let post = box_solid(Vec3::new(14.0, 0.0, 0.0), Vec3::new(28.0, 6.0, 10.0)).unwrap();
     let mids = [Vec3::new(14.0, 0.0, 5.0), Vec3::new(28.0, 0.0, 5.0), Vec3::new(14.0, 6.0, 5.0), Vec3::new(28.0, 6.0, 5.0)];
-    assert_eq!(fillet_max_each(&post, &mids, 3.5).unwrap().map(|x| x.0), Some(vec![3.0; 4]));
+    assert_eq!(fillet_max_each(&post, &mids, 3.5, FilletTurn::Mitre).unwrap().map(|x| x.0), Some(vec![3.0; 4]));
 }
 
 /// R21 on an edge of a 20 mm cube overflows on its tangent sides, which a round may, taking all
@@ -2439,17 +2439,3 @@ fn a_box_cut_round_a_small_hole_of_a_long_plate_keeps_the_hole() {
         }
     }
 }
-
-/// A refusal is kept with its body for every later reader: which face it names doesn't depend on
-/// whether the job that found it had been stopped, whose probes would all be refused.
-#[test]
-fn a_stopped_job_does_not_decide_which_face_a_refusal_names() {
-    let body = crate::build::box_solid(Vec3::ZERO, Vec3::new(10.0, 10.0, 10.0)).unwrap();
-    let why = solidcraft_smlib::Error::Argument;
-    let plain = crate::body::Refusal::of(body.record(), &why);
-    assert_eq!(plain.face, None, "every face of a box is taken on its own");
-    let stop = crate::Stop::new();
-    stop.stop();
-    let stopped = stop.within(|| crate::body::Refusal::of(body.record(), &why));
-    assert_eq!(stopped.face, plain.face);
-}

crates/mcp/src/server.rs

@@ -38,7 +38,7 @@ ids, plane axes, worked examples and the known traps of this version; `file: \"S
 Plan: work the numbers out first (the parameters, the expected volume and bounding box after each stage, the world point you \
 will use for each edge or face pick). Then build in a few `batch` calls (all-or-nothing; the reply names the failing step; \
 `save`, `measure` and `set_parameter` can be steps). Use `verbose: false`. Name every feature. `list_commands {\"filter\": word}` \
-gives ids and one-line parameter docs (never unfiltered); `describe_command` gives one command's docs and schemas.\n\n\
+gives ids and one-line parameter docs (never unfiltered: it also takes prefix, panel, compact: true and limit); `describe_command` gives one command's docs and schemas.\n\n\
 Routes: a plate, block, boss, standoff or hole is cheapest as a primitive with expression fields (`solid.box`, `solid.cylinder`, \
 `solid.hole`, `solid.fillet`, `solid.shell`, patterns and mirror), no sketch. Sketch when the profile is not a box or a circle. \
 Fillet outside edges before shelling, build inside features after the shell, then the holes and cuts through walls. Give a blind \

crates/mcp/src/tests.rs

@@ -1741,6 +1741,75 @@ fn list_commands_filter_by_a_command_id_matches_ids() {
     assert!(ids.iter().all(|id| id.contains("sketch.delete")), "{} commands matched: {ids:?}", ids.len());
 }
 
+/// #11726: `list_commands` narrows by id prefix and by panel, shrinks each entry to id and label
+/// or to chosen keys, and pages; with none of these the reply is the whole catalog as before. A
+/// batch step narrows the same way, and a bad argument is a tool error that names it.
+#[test]
+fn list_commands_narrows_by_prefix_panel_fields_and_page() {
+    let mut s = server();
+    let all = tool(&mut s, "list_commands", json!({}));
+    let all = all.as_array().unwrap();
+    assert!(all.len() > 100 && all[0].get("params").is_some(), "the whole catalog, every key");
+    let ids = |v: &Value| v.as_array().unwrap().iter().map(|c| c["id"].as_str().unwrap().to_string()).collect::<Vec<_>>();
+    let sketch = tool(&mut s, "list_commands", json!({"prefix": "SKETCH."}));
+    assert!(!ids(&sketch).is_empty() && ids(&sketch).iter().all(|id| id.starts_with("sketch.")), "{:?}", ids(&sketch));
+    let want = all.iter().filter(|c| c["id"].as_str().unwrap().starts_with("sketch.")).count();
+    assert_eq!(ids(&sketch).len(), want, "every sketch command, not only those on a toolbar");
+    let modify = tool(&mut s, "list_commands", json!({"panel": "modify"}));
+    assert!(!ids(&modify).is_empty(), "{modify}");
+    assert!(
+        modify
+            .as_array()
+            .unwrap()
+            .iter()
+            .all(|c| c["panel"].as_str().unwrap().eq_ignore_ascii_case("modify") || c["tab"].as_str().unwrap().eq_ignore_ascii_case("modify")),
+        "only the whole panel name matches"
+    );
+    let compact = tool(&mut s, "list_commands", json!({"compact": true}));
+    assert_eq!(ids(&compact), ids(&Value::Array(all.clone())), "compact keeps every command");
+    assert!(compact.as_array().unwrap().iter().all(|c| c.as_object().unwrap().keys().eq(["id", "label"].iter())), "{}", compact[0]);
+    assert!(compact.to_string().len() * 5 < Value::Array(all.clone()).to_string().len(), "compact is far smaller");
+    let picked = tool(&mut s, "list_commands", json!({"prefix": "solid.fillet", "fields": ["id", "enabled"], "compact": true}));
+    assert_eq!(picked[0], json!({"id": "solid.fillet", "enabled": picked[0]["enabled"]}), "fields wins over compact");
+    // Pages: together they are the whole match list, in order.
+    let mut paged = Vec::new();
+    let mut offset = json!(0);
+    while let Some(at) = offset.as_u64() {
+        let page = tool(&mut s, "list_commands", json!({"prefix": "sketch.", "compact": true, "limit": 7, "offset": at}));
+        assert_eq!(page["total"], want, "{page}");
+        assert_eq!(page["offset"], at);
+        assert!(page["commands"].as_array().unwrap().len() <= 7);
+        paged.extend(ids(&page["commands"]));
+        offset = page["next_offset"].clone();
+    }
+    assert_eq!(paged, ids(&sketch));
+    let past = tool(&mut s, "list_commands", json!({"limit": 5, "offset": 1_000_000}));
+    assert_eq!((past["commands"].as_array().unwrap().len(), &past["next_offset"]), (0, &Value::Null), "{past}");
+    // A batch step narrows as the tool does.
+    let r = tool(&mut s, "batch", json!({"commands": [{"command": "list_commands", "params": {"prefix": "sketch.", "compact": true, "limit": 3}}]}));
+    let step = r["results"][0].clone();
+    assert_eq!(step["commands"].as_array().map(Vec::len), Some(3), "{r}");
+    assert_eq!(step["total"], want, "{r}");
+    for bad in [
+        json!({"limit": 0}),
+        json!({"limit": -1}),
+        json!({"offset": "x"}),
+        json!({"fields": ["nope"]}),
+        json!({"fields": "id"}),
+        json!({"compact": 1}),
+        json!({"prefix": 3}),
+    ] {
+        // The argument schema refuses a wrong type before the tool runs; the tool refuses the rest.
+        let r = raw_tool(&mut s, "list_commands", bad.clone());
+        let text = r["result"]["content"][0]["text"].as_str().or(r["error"]["message"].as_str()).unwrap_or_default().to_string();
+        assert!(r["result"]["isError"] == json!(true) || r["error"]["code"].is_i64(), "{bad}: {r}");
+        let key = bad.as_object().unwrap().keys().next().unwrap().clone();
+        assert!(text.contains(&format!("`{key}`")), "{bad}: the error names the argument: {text}");
+        let r = raw_tool(&mut s, "batch", json!({"commands": [{"command": "list_commands", "params": bad.clone()}]}));
+        assert!(r["result"]["isError"] == json!(true) || r.to_string().contains(&format!("`{key}`")), "{bad} as a step: {r}");
+    }
+}
+
 /// Compatibility shims (docs/compatibility.md): a design saved before the rename (legacy
 /// extension and format tag) opens through MCP, and the legacy resource URIs still read.
 #[test]
@@ -3480,9 +3549,9 @@ fn a_bridged_server_checks_calls_at_its_param_check_level() {
     assert_eq!(r["result"]["isError"], json!(true), "{r}");
     assert!(text(&r).contains(&format!("invalid parameters for `solid.box`: {warning}")), "{r}");
     assert_eq!(sent("engine.execute solid.box"), 0, "refused unsent");
-    let r = raw_tool(&mut s, "execute", json!({"command": "solid.fillet", "params": {"nonsense": 1}}));
+    let r = raw_tool(&mut s, "execute", json!({"command": "solid.chamfer", "params": {"nonsense": 1}}));
     assert_ne!(r["result"]["isError"], json!(true), "{r}");
-    assert_eq!(sent("engine.execute solid.fillet"), 1, "no contract here: the app decides");
+    assert_eq!(sent("engine.execute solid.chamfer"), 1, "no contract here: the app decides");
     let r = raw_tool(&mut s, "batch", json!({"commands": [good, misspelt]}));
     assert_eq!(r["result"]["isError"], json!(true), "{r}");
     let reply: Value = serde_json::from_str(&text(&r)).unwrap();

crates/mcp/src/tools.rs

@@ -102,8 +102,26 @@ pub fn tool_definitions() -> Vec<Value> {
              enabled right now. Ids are dotted and lower-case (solid.extrude, sketch.create, \
              solid.fillet, sketch.inspect, timeline.rollback). Optional case-insensitive \
              substring `filter` over id, label, tab and panel (not the parameter docs, so a command id \
-             finds that command rather than every command whose docs mention it).",
-            obj(json!({"filter": string("Substring to match, e.g. \"sketch\", \"fillet\", \"pattern\"")}), &[]),
+             finds that command rather than every command whose docs mention it). Narrow it further with `prefix` \
+             (start of the id) and `panel` (a whole panel or tab name); shrink each entry with `compact` (id and label) \
+             or `fields`; page it with `limit` and `offset`, which make the reply {commands, total, offset, next_offset}. \
+             With none of these the reply is the whole catalog, about 350 KB.",
+            obj(
+                json!({
+                    "filter": string("Substring to match, e.g. \"sketch\", \"fillet\", \"pattern\""),
+                    "prefix": string("Case-insensitive start of the command id, e.g. \"sketch.\""),
+                    "panel": string("A whole toolbar panel or tab name, case-insensitive, e.g. \"Modify\" or \"SKETCH\""),
+                    "compact": {"type": "boolean", "description": "Each entry is only {id, label} (default false)"},
+                    "fields": {
+                        "type": "array",
+                        "items": {"type": "string", "enum": COMMAND_FIELDS},
+                        "description": "Keep only these keys of each entry; overrides `compact`",
+                    },
+                    "limit": {"type": "integer", "minimum": 1, "description": "At most this many commands; the reply becomes {commands, total, offset, next_offset}"},
+                    "offset": {"type": "integer", "minimum": 0, "description": "Skip this many matches first (default 0); with it the reply is paged as with `limit`"},
+                }),
+                &[],
+            ),
             Effect::ReadOnly,
         ),
         tool(
@@ -146,7 +164,7 @@ pub fn tool_definitions() -> Vec<Value> {
             "Run commands in order, stopping at the first error. Each step is {command, params}: an engine command id \
              (as list_commands lists them). A step may also name one of these tools with that tool's arguments as params, \
              and runs the engine command it stands for: set_parameter (parameters.change; `value` or `expression`), \
-             list_commands (engine.commands, with `filter`), describe_command (engine.describe), execute ({command, params}), \
+             list_commands (engine.commands, narrowed by its arguments), describe_command (engine.describe), execute ({command, params}), \
              measure (inspect.measure), compare_picture (inspect.compare_picture, numbers only: no overlay PNG), \
              inspect_design (document.inspect), undo, redo, export, save, open, new_design, crash_reports; screenshot, \
              body_topology, batch and pending can't be steps. On an error the steps already run are undone (unless \
@@ -867,8 +885,9 @@ fn measure_summary_wanted(a: &Map<String, Value>) -> bool {
 fn dispatch(b: &mut dyn Backend, name: &str, a: &Map<String, Value>) -> Result<Value, String> {
     match name {
         "list_commands" => {
+            let query = CommandQuery::parse(a)?;
             let all = b.call("engine.commands", json!({}))?;
-            Ok(filter_commands(all, str_arg(a, "filter")))
+            Ok(query.apply(all))
         }
         "describe_command" => {
             let id = str_arg(a, "id").ok_or("`id` is required")?;
@@ -941,11 +960,100 @@ fn dispatch(b: &mut dyn Backend, name: &str, a: &Map<String, Value>) -> Result<V
 
 /// The command catalog filtered by a case-insensitive substring of id, label, panel or tab
 /// (`list_commands`; not the parameter docs, which name other commands, #269).
-fn filter_commands(all: Value, filter: Option<&str>) -> Value {
-    let Some(f) = filter.map(str::to_lowercase).filter(|f| !f.is_empty()) else { return all };
-    let hit =
-        |c: &Value| ["id", "label", "panel", "tab"].iter().any(|k| c.get(*k).and_then(Value::as_str).is_some_and(|s| s.to_lowercase().contains(&f)));
-    Value::Array(all.as_array().map(|v| v.iter().filter(|c| hit(c)).cloned().collect()).unwrap_or_default())
+/// The keys of a `list_commands` entry, which `fields` may keep.
+const COMMAND_FIELDS: &[&str] = &["id", "label", "tab", "panel", "icon", "shortcut", "params", "enabled", "disabled_reason", "planned"];
+
+/// How `list_commands` narrows the catalog (#11726): which commands, which keys of each, and
+/// which page. The default keeps the whole catalog as it is.
+#[derive(Clone, Debug, Default, PartialEq)]
+struct CommandQuery {
+    filter: Option<String>,
+    prefix: Option<String>,
+    panel: Option<String>,
+    fields: Option<Vec<String>>,
+    limit: Option<usize>,
+    offset: Option<usize>,
+}
+
+impl CommandQuery {
+    fn parse(a: &Map<String, Value>) -> Result<Self, String> {
+        let text = |k: &str| -> Result<Option<String>, String> {
+            match a.get(k) {
+                None | Some(Value::Null) => Ok(None),
+                Some(Value::String(s)) => Ok(Some(s.to_lowercase()).filter(|s| !s.is_empty())),
+                Some(_) => Err(format!("`{k}` must be a string")),
+            }
+        };
+        let count = |k: &str, least: u64| -> Result<Option<usize>, String> {
+            match a.get(k) {
+                None | Some(Value::Null) => Ok(None),
+                Some(v) => v
+                    .as_u64()
+                    .filter(|n| *n >= least)
+                    .map(|n| Some(usize::try_from(n).unwrap_or(usize::MAX)))
+                    .ok_or_else(|| format!("`{k}` must be a whole number of at least {least}")),
+            }
+        };
+        let compact = match a.get("compact") {
+            None | Some(Value::Null) => false,
+            Some(v) => v.as_bool().ok_or("`compact` must be true or false")?,
+        };
+        let fields = match a.get("fields") {
+            None | Some(Value::Null) => compact.then(|| vec!["id".to_string(), "label".to_string()]),
+            Some(Value::Array(v)) => {
+                let mut keep = Vec::new();
+                for f in v {
+                    let name = f.as_str().filter(|n| COMMAND_FIELDS.contains(n)).ok_or_else(|| {
+                        let shown: String = f.to_string().chars().take(64).collect();
+                        format!("`fields` takes the entry keys {}; not {shown}", COMMAND_FIELDS.join(", "))
+                    })?;
+                    if !keep.iter().any(|k| k == name) {
+                        keep.push(name.to_string());
+                    }
+                }
+                Some(keep)
+            }
+            Some(_) => return Err("`fields` must be a list of entry keys".into()),
+        };
+        Ok(Self {
+            filter: text("filter")?,
+            prefix: text("prefix")?,
+            panel: text("panel")?,
+            fields,
+            limit: count("limit", 1)?,
+            offset: count("offset", 0)?,
+        })
+    }
+
+    fn matches(&self, c: &Value) -> bool {
+        let field = |k: &str| c.get(k).and_then(Value::as_str).map(str::to_lowercase).unwrap_or_default();
+        self.filter.as_ref().is_none_or(|f| ["id", "label", "panel", "tab"].iter().any(|k| field(k).contains(f.as_str())))
+            && self.prefix.as_ref().is_none_or(|p| field("id").starts_with(p.as_str()))
+            && self.panel.as_ref().is_none_or(|p| field("panel") == *p || field("tab") == *p)
+    }
+
+    /// The catalog narrowed: a list, or `{commands, total, offset, next_offset}` when paged.
+    fn apply(&self, all: Value) -> Value {
+        let Value::Array(all) = all else { return all };
+        let hits: Vec<Value> = all.into_iter().filter(|c| self.matches(c)).collect();
+        let total = hits.len();
+        let offset = self.offset.unwrap_or(0).min(total);
+        let take = self.limit.unwrap_or(usize::MAX);
+        let page: Vec<Value> = hits
+            .into_iter()
+            .skip(offset)
+            .take(take)
+            .map(|c| match (&self.fields, c) {
+                (Some(keep), Value::Object(m)) => Value::Object(m.into_iter().filter(|(k, _)| keep.contains(k)).collect()),
+                (_, c) => c,
+            })
+            .collect();
+        if self.limit.is_none() && self.offset.is_none() {
+            return Value::Array(page);
+        }
+        let end = offset + page.len();
+        json!({"commands": page, "total": total, "offset": offset, "next_offset": (end < total).then_some(end)})
+    }
 }
 
 /// `pending`: the end of a request still running when its call returned (bridged only; a
@@ -975,8 +1083,8 @@ fn pending(b: &mut dyn Backend) -> Result<Value, String> {
 
 /// How a tool step's result is cut down to what the tool itself would reply.
 enum Narrow {
-    /// A `list_commands` step's catalog, filtered as the tool filters it.
-    Commands(String),
+    /// A `list_commands` step's catalog, narrowed as the tool narrows it.
+    Commands(CommandQuery),
     /// A `measure {summary: true}` step's reply, as `measure_summary` shapes it.
     MeasureSummary,
 }
@@ -984,7 +1092,7 @@ enum Narrow {
 impl Narrow {
     fn apply(&self, v: Value) -> Value {
         match self {
-            Narrow::Commands(f) => filter_commands(v, Some(f)),
+            Narrow::Commands(q) => q.apply(v),
             Narrow::MeasureSummary => measure_summary(v),
         }
     }
@@ -1010,7 +1118,10 @@ fn batch_step(step: &Value) -> Result<(String, Value, Option<Narrow>), String> {
     let a = params.as_object().unwrap_or(&empty);
     let mapped = |c: &str, p: Value| Ok((c.to_string(), p, None));
     match command {
-        "list_commands" => Ok(("engine.commands".into(), json!({}), str_arg(a, "filter").map(|f| Narrow::Commands(f.to_string())))),
+        "list_commands" => {
+            let query = CommandQuery::parse(a)?;
+            Ok(("engine.commands".into(), json!({}), (query != CommandQuery::default()).then_some(Narrow::Commands(query))))
+        }
         "set_parameter" => {
             let mut p = pick(a, &["name", "unit", "comment"]);
             p["expression"] = parameter_value(a)?;

crates/smlib/src/core.rs

@@ -11,7 +11,7 @@ use std::sync::{Mutex, PoisonError};
 
 use solidcore::geom::attribute::{AttributeStore, ObjectKey};
 use solidcore::geom::vector3d::Vec3;
-use solidcore::kernel::{CancelToken, Kernel, KernelOptions, Rng, UpstreamFixes};
+use solidcore::kernel::{Kernel, KernelOptions, UpstreamFixes};
 use solidcore::mass::integrator::properties::{PropertyAttributes, brep_volume};
 use solidcore::primitive::api_primitives as primitives;
 
@@ -412,8 +412,7 @@ const HELD_BACK: &[&str] = &["fillet_refuse_rounds_breaking_through"];
 
 /// How far apart two kernels' procedural blend serials start. A body keeps the serials of the
 /// kernel that made it and may be used on any other, whose memo of solved stations is keyed by
-/// serial alone: the ranges keep one definition's stations from answering for another's. A serial
-/// only names a definition, so which range one comes from changes no answer.
+/// serial alone: the ranges keep one definition's stations from answering for another's.
 pub(crate) const BLEND_SERIALS_PER_KERNEL: u64 = 1 << 40;
 
 /// A new kernel. Each takes the next range of blend serials, the first starting at 0.
@@ -425,85 +424,30 @@ fn fresh() -> Kernel {
     k
 }
 
-/// The kernels calls run on. The lock is only held to take or put back a kernel, never during a
-/// call: a call that runs long (or never returns) holds up nothing but its own body, so one
-/// design's long operation never delays another's. Calls one after another all get the same
-/// kernel; one that starts while another runs gets one of its own (solidcore keeps no global
-/// state, and a body's identities are valid only in the kernel that issued them, so any kernel
-/// takes any body).
-///
-/// A call stuck for good keeps its kernel and the thread it runs on, and costs nothing more: at
-/// most `most_idle` kernels wait between calls, however many calls once ran side by side. A job
-/// that starts again and sticks again holds one more each time, so at `most_running` calls a new
-/// call fails, saying so, rather than grow without end or wait for calls that may never return.
-pub(crate) struct Pool<K> {
-    pub(crate) idle: Vec<K>,
-    pub(crate) running: usize,
-    pub(crate) most_idle: usize,
-    pub(crate) most_running: usize,
+/// Most kernels kept for later calls; those over it are dropped when their call ends.
+const MOST_IDLE: usize = 8;
+
+/// The kernels no call is using, the last used on top. The lock is only held to take or put back
+/// a kernel, never during a call: a call that runs long (or never returns) holds up nothing but
+/// its own body, so one design's long operation never delays another's. Calls one after another
+/// all get the same kernel, as a single kernel would serve them; one that starts while another
+/// runs gets one of its own (solidcore keeps no global state, and a body's identities are valid
+/// only in the kernel that issued them, so any kernel takes any body).
+static IDLE: Mutex<Vec<Kernel>> = Mutex::new(Vec::new());
+
+fn take_kernel() -> Kernel {
+    IDLE.lock().unwrap_or_else(PoisonError::into_inner).pop().unwrap_or_else(fresh)
 }
 
-impl<K> Pool<K> {
-    /// A kernel for a call, the last used first; `None` when too many are running.
-    pub(crate) fn take(&mut self, make: impl FnOnce() -> K) -> Option<K> {
-        if self.running >= self.most_running {
-            return None;
-        }
-        self.running += 1;
-        Some(self.idle.pop().unwrap_or_else(make))
+fn put_kernel(k: Kernel) {
+    let mut idle = IDLE.lock().unwrap_or_else(PoisonError::into_inner);
+    if idle.len() < MOST_IDLE {
+        idle.push(k);
     }
-
-    /// A call ended, handing back its kernel if it is fit to use again.
-    pub(crate) fn put(&mut self, kernel: Option<K>) {
-        self.running = self.running.saturating_sub(1);
-        if let Some(kernel) = kernel
-            && self.idle.len() < self.most_idle
-        {
-            self.idle.push(kernel);
-        }
-    }
-}
-
-/// Most calls at once. Far above what any work needs: an operation runs on at most 16 threads.
-const MOST_RUNNING: usize = 256;
-
-static POOL: Mutex<Pool<Kernel>> = Mutex::new(Pool { idle: Vec::new(), running: 0, most_idle: 8, most_running: MOST_RUNNING });
-
-fn take_kernel() -> Option<Kernel> {
-    POOL.lock().unwrap_or_else(PoisonError::into_inner).take(fresh)
-}
-
-fn put_kernel(k: Option<Kernel>) {
-    POOL.lock().unwrap_or_else(PoisonError::into_inner).put(k);
-}
-
-/// What a call must not find from the calls before it: the same operation on the same bodies
-/// answers the same on any kernel, however much that kernel did first. (Its draws of random rays,
-/// the stations it remembers; marks, identities and what is only kept to reuse memory change no
-/// answer. Tolerances and fixes are the same on every kernel.)
-fn start_clean(k: &mut Kernel) {
-    k.rng = Rng::new(KernelOptions::default().seed);
-    *k.blend_station_memo.borrow_mut() = Default::default();
-    k.fillet_point_step.set(None);
-    k.upstream_ub_passed.clear();
-}
-
-/// A kernel kept out of use until dropped ([`crate::hold_a_kernel`]).
-pub struct HeldKernel(Option<Kernel>);
-
-impl Drop for HeldKernel {
-    fn drop(&mut self) {
-        put_kernel(self.0.take());
-    }
-}
-
-pub(crate) fn hold_a_kernel() -> HeldKernel {
-    HeldKernel(take_kernel())
 }
 
 /// Runs `f` on a kernel of its own. A panic in solidcore is caught: the kernel, which it may have
-/// left half-updated, is dropped and the call fails with [`Error::Internal`]. A token over this
-/// thread's work ([`crate::stop`]) stops it.
+/// left half-updated, is replaced by a fresh one and the call fails with [`Error::Internal`].
 pub(crate) fn run<T: dump::Answer>(call: &'static str, f: impl FnOnce(&mut Kernel) -> std::result::Result<T, solidcore::SolidError>) -> Result<T> {
     run_on(call, &[], f)
 }
@@ -526,26 +470,7 @@ pub(crate) fn run_on<T: dump::Answer>(
     inputs: dump::Inputs<'_>,
     f: impl FnOnce(&mut Kernel) -> std::result::Result<T, solidcore::SolidError>,
 ) -> Result<T> {
-    let stop = crate::stop::token();
-    if stop.as_ref().is_some_and(CancelToken::is_cancelled) {
-        return Err(Error::Solidcore(format!("{call}: cancelled")));
-    }
-    call_on(call, inputs, stop, f)
-}
-
-/// [`run_on`], stopped by `stop`.
-fn call_on<T: dump::Answer>(
-    call: &'static str,
-    inputs: dump::Inputs<'_>,
-    stop: Option<CancelToken>,
-    f: impl FnOnce(&mut Kernel) -> std::result::Result<T, solidcore::SolidError>,
-) -> Result<T> {
-    let Some(mut k) = take_kernel() else {
-        log::warn!(target: "smlib", "{call}: refused, {MOST_RUNNING} kernel calls are still running");
-        return Err(Error::Solidcore(format!("{call}: {MOST_RUNNING} kernel calls are still running")));
-    };
-    start_clean(&mut k);
-    k.cancel = stop.clone();
+    let mut k = take_kernel();
     // A profiler span per call: where the kernel's time goes.
     let _span = solidcraft_profile::span("solidcore", call);
     let in_flight = dump::in_flight(call);
@@ -570,11 +495,6 @@ fn call_on<T: dump::Answer>(
         }
     };
     drop(in_flight);
-    // Stopped, it is no failure to look into, and solidcore may have left the kernel part way.
-    if stop.is_some_and(|s| s.is_cancelled()) {
-        put_kernel(None);
-        return r;
-    }
     let why = match &r {
         Ok(v) => v.refusal(),
         Err(e) => Some(e.to_string()),
@@ -583,8 +503,7 @@ fn call_on<T: dump::Answer>(
         // The kernel the call ran on, or the fresh one that replaced it after a panic.
         dump::failed(&k, call, &why, inputs);
     }
-    k.cancel = None;
-    put_kernel(Some(k));
+    put_kernel(k);
     r
 }
 
@@ -611,8 +530,7 @@ pub(crate) fn with_body<T: dump::Answer>(
     if body.0.is_poisoned() {
         return Err(Error::Internal(format!("{call}: the body was left unfinished by an earlier panic")));
     }
-    // No token stops it: stopped part way, solidcore may leave the body it borrows half-changed.
-    call_on(call, &[("brep", body)], None, |k| f(k, &mut body.0.lock().unwrap_or_else(PoisonError::into_inner)))
+    run_on(call, &[("brep", body)], |k| f(k, &mut body.0.lock().unwrap_or_else(PoisonError::into_inner)))
 }
 
 /// An axis-aligned box from its lower corner (`SmApiCreateBox`, as `smlib_make_box` checks it:

crates/smlib/src/core/blend.rs

@@ -53,7 +53,7 @@ use solidcore::topology::topology_traverser::Marks;
 use solidcore::topology::{Brep, EdgeId, EdgeuseId, FaceId, FaceuseId, VertexId, edge, vertex};
 
 use super::{Body, answer};
-use crate::{Blend, ChamferSecond, Error, Hole, HoleEdge, MAX_POINTS, Result};
+use crate::{Blend, ChamferSecond, Error, Hole, HoleEdge, MAX_POINTS, Result, Turn};
 
 /// Why solidcore refuses the 3x2 mixed-convexity corner whose rails cross
 /// (`fixes.fillet_refuse_mixed_corner_crossing_rails`, [`MIXED_CORNER_RAILS_CROSS`]): it builds no
@@ -248,7 +248,9 @@ fn chamfer_radius(k: &Kernel, b: &mut Brep, e: EdgeId, distance: f64) -> solidco
 /// What `round_edges` makes: the capi's kinds less the chamfer, which `chamfer_offsets` makes.
 #[derive(Clone, Copy, PartialEq)]
 enum Section<'a> {
-    Round,
+    /// A circular section of constant radius (or of a variable radius's law), the turns of two
+    /// such rounds at a side edge as the [`Turn`] says (`SetSweptTurns`).
+    Round(Turn),
     /// The curvature-continuous section (`SM_FSG_BLEND_CURVE`): the Gⁿ generator's order 2 at the
     /// equal-area thumbweight (`SMLIB_BLEND_THUMBWEIGHT`, fork 6148773; solidcore#2261 under
     /// `fillet_gn_section_generator`), which takes off what the ball's circle does.
@@ -338,6 +340,23 @@ fn room_reason(r: NoRoomReason) -> Option<crate::RoomReason> {
     })
 }
 
+/// The refusal of a swept turn `CreateFilletCorners` noted at its vertex (`SmBlendCorner::Classify`
+/// with `GetSweptTurns()`): [`Error::TurnRefused`] with solidcore's reason, without its "Fillet
+/// Error: " prefix, and where it is; `None` for a note of another kind.
+fn turn_refusal(info: &ErrorInfo<FilletObject>) -> Option<Error> {
+    let room = match info.code {
+        c if c == FilletErrorType::NoRoom as i32 => true,
+        c if c == FilletErrorType::CornerUnsupported as i32 => false,
+        _ => return None,
+    };
+    let why = info.comment.trim();
+    if why.is_empty() {
+        return None;
+    }
+    let why = why.strip_prefix("Fillet Error:").map_or(why, str::trim_start).to_owned();
+    Some(Error::TurnRefused { room, why, at: info.location.map(|p| [p.x, p.y, p.z]) })
+}
+
 /// [`blend_failure`] where solidcore gives no size.
 fn blend_failure_unsized(info: &ErrorInfo<FilletObject>, e: SolidError, corner: bool) -> Error {
     if e.is_unported() {
@@ -433,13 +452,16 @@ fn blend_edges_stopping(
     let mut fit_edge = None;
     let done = {
         let mut s = FilletSession::new(k, b)?;
+        // `SetSweptTurns`: read as the corners are made (`fixes.fillet_blend_corner`).
+        let swept = section == Section::Round(Turn::Swept);
+        s.set_swept_turns(swept);
         // `SetFilletParameters(b, es, sections, solvers, values, laws, -1, -1, -1, -1,
         // continuity 1, thumbweight 1)`: the session sets the executive's global merge first, as
         // `SmApiFilletEdges` does, and `SetFilletParameters` resets it, as in the capi.
         let prepared = match (section, law) {
-            (Section::Round, None) => s.prepare_per_edge_constant_radius(k, edges, sizes, &[FilletSurfaceGeneratorType::Circular], 1, 1.0),
+            (Section::Round(_), None) => s.prepare_per_edge_constant_radius(k, edges, sizes, &[FilletSurfaceGeneratorType::Circular], 1, 1.0),
             // The size is the start radius (`smlib_fillet_variable`).
-            (Section::Round, Some(law)) => match sizes.first() {
+            (Section::Round(_), Some(law)) => match sizes.first() {
                 Some(&size) => s.prepare_variable_radius_edges(k, edges, size, law, 1, 1),
                 None => return Ok(Err(Err(Error::Argument))),
             },
@@ -459,7 +481,10 @@ fn blend_edges_stopping(
                 s.add_set_back_vertex(sb.vertex);
             }
         }
+        let prepared_ok = prepared.is_ok();
         let mut step = prepared.and_then(|()| s.create_corners(k, None)).map(|()| Ok(Vec::new()));
+        // A swept turn `CreateFilletCorners` refused, with solidcore's reason ([`turn_refusal`]).
+        let refused_turn = if swept && prepared_ok && step.is_err() { turn_refusal(s.error_info()) } else { None };
         // A vertex `CreateFilletCorners` made no corner for, noted before a later step notes its
         // own failure over it ([`blend_failure`]).
         let corner = step.is_ok() && s.error_info().code == FilletErrorType::CornerUnsupported as i32;
@@ -488,11 +513,14 @@ fn blend_edges_stopping(
                 }
             },
             Ok(Err(refusal)) => Ok(Err(refusal)),
-            Err(e) => {
-                let (why, edge) = blend_failure(&s, e, corner);
-                fit_edge = edge;
-                Ok(Err(Err(why)))
-            }
+            Err(e) => match refused_turn {
+                Some(why) => Ok(Err(Err(why))),
+                None => {
+                    let (why, edge) = blend_failure(&s, e, corner);
+                    fit_edge = edge;
+                    Ok(Err(Err(why)))
+                }
+            },
         }
     };
     let done: solidcore::Result<std::result::Result<(Vec<usize>, Vec<(usize, FaceId)>), std::result::Result<usize, Error>>> = done;
@@ -825,9 +853,9 @@ pub(crate) fn blend(
 
 /// `smlib_blend_dropping`: [`blend`] with one size per point, no corners, and per point whether it
 /// picked an edge that a larger round, overflowing its faces, removed whole.
-pub(crate) fn blend_dropping(body: &Body, kind: Blend, points: &[[f64; 3]], sizes: &[f64], tolerance: f64) -> Result<(Body, Vec<bool>)> {
+pub(crate) fn blend_dropping(body: &Body, kind: Blend, turn: Turn, points: &[[f64; 3]], sizes: &[f64], tolerance: f64) -> Result<(Body, Vec<bool>)> {
     let mut dropped = vec![false; points.len()];
-    let (b, _) = blend_call(body, kind, points, sizes, tolerance, &[], &[], Corners::Filled, &mut dropped)?;
+    let (b, _) = blend_call(body, kind, turn, points, sizes, tolerance, &[], &[], Corners::Filled, &mut dropped)?;
     Ok((b, dropped))
 }
 
@@ -846,15 +874,17 @@ pub(crate) fn blend_holes(
     setbacks: &[f64],
     open: Corners,
 ) -> Result<(Body, Vec<Hole>)> {
-    blend_call(body, kind, points, sizes, tolerance, corners, setbacks, open, &mut vec![false; points.len()])
+    blend_call(body, kind, Turn::Mitre, points, sizes, tolerance, corners, setbacks, open, &mut vec![false; points.len()])
 }
 
 /// `blend_call`: [`blend_holes`], with per point in `dropped` whether it picked an edge an
-/// overflowing round removed whole ([`overflow_first`]).
+/// overflowing round removed whole ([`overflow_first`]), and the rounds' turns at side edges as
+/// `turn` says (a swept turn is for [`Blend::Round`] only).
 #[allow(clippy::too_many_arguments)] // the capi's blend_call
 fn blend_call(
     body: &Body,
     kind: Blend,
+    turn: Turn,
     points: &[[f64; 3]],
     sizes: &[f64],
     tolerance: f64,
@@ -869,6 +899,7 @@ fn blend_call(
         || !(one_size || sizes.len() == points.len())
         || !points_ok(corners, true)
         || setbacks.len() != corners.len()
+        || (turn == Turn::Swept && kind != Blend::Round)
     {
         return Err(Error::Argument);
     }
@@ -898,7 +929,7 @@ fn blend_call(
         }
         let solid_in = brep_p2::is_manifold_solid(&w)?;
         let section = match kind {
-            Blend::Round => Section::Round,
+            Blend::Round => Section::Round(turn),
             // Every edge of one call takes the equal-area thumbweight of the first's wedge
             // (solidcore#2250's comment 6563419897): edges of other wedges would take off another
             // area than their own, so they are not built together.
@@ -1380,7 +1411,7 @@ pub(crate) fn fillet_variable(
         // (`NoRoomReason::BallsFold`), [`Error::NoRoom`].
         let solid_in = brep_p2::is_manifold_solid(&w)?;
         let (r0, r1) = (radii.first().copied().unwrap_or(0.0), radii.last().copied().unwrap_or(0.0));
-        Ok(match blend_edges(k, &mut w, &[e], &[r0.max(r1)], Section::Round, Some(law), &[], None)? {
+        Ok(match blend_edges(k, &mut w, &[e], &[r0.max(r1)], Section::Round(Turn::Mitre), Some(law), &[], None)? {
             Ok(()) => finish(w, solid_in)?,
             Err(Ok(_)) => Err(Error::Unsupported),
             Err(Err(e)) => Err(e),

crates/smlib/src/core/blend_tests.rs

@@ -12,7 +12,7 @@ use super::blend::{Corners, blend, blend_dropping, blend_holes, chamfer_sides, f
 use super::boolean::boolean;
 use super::{Body, counts, make_box, make_cylinder, to_arrays, volume};
 use crate::export::native;
-use crate::{Blend, BooleanOp, ChamferSecond, Error};
+use crate::{Blend, BooleanOp, ChamferSecond, Error, Turn};
 
 /// A case longer than this is a hang.
 const TIMEOUT: Duration = Duration::from_secs(300);
@@ -399,7 +399,7 @@ fn overflow_goes_first() {
     ];
     for (points, sizes, dropped, want, bound) in cases {
         let got = timed("overflow_first", move || {
-            let (b, d) = blend_dropping(&Shape::Box([0.0; 3], [20.0; 3]).core(), Blend::Round, points, sizes, 1.0).unwrap();
+            let (b, d) = blend_dropping(&Shape::Box([0.0; 3], [20.0; 3]).core(), Blend::Round, Turn::Mitre, points, sizes, 1.0).unwrap();
             native(&to_arrays(&b).unwrap()).unwrap();
             (volume(&b, 1e-8).unwrap(), d)
         });
@@ -445,6 +445,71 @@ fn rounds_at_a_concave_face_corner_are_mitred() {
     assert!(rel(got, v) < 1e-8, "{got} vs {v}");
 }
 
+/// A 40 x 30 x 10 plate with a 10 x 10 x 5 boss on it (x 15..25, y 10..20), the boss's four base
+/// edges rounded at r 1: at each upright boss edge two concave rounds turn round the sharp convex
+/// edge. Each base edge gains the spandrel A = (1 - π/4) r² along its 10, and each corner the
+/// rounds' part beyond both walls, whose section's first moment about the upright edge is
+/// M = (5/6 - π/4) r³: mitred, 8 M in all; swept, the section revolved a quarter turn at each,
+/// 2π M, the corner a horn torus of radii r, r. Swept with unequal radii, or along a pocket's floor
+/// (its upright edges sharp and concave), is refused with solidcore's reason.
+#[test]
+fn rounds_turning_round_a_boss_edge_mitred_or_swept() {
+    let made = |a: Body, b: Body, op| boolean(&a, &b, op).unwrap().unwrap();
+    let boss =
+        move || made(make_box([0.0; 3], [40.0, 30.0, 10.0]).unwrap(), make_box([15.0, 10.0, 10.0], [10.0, 10.0, 5.0]).unwrap(), BooleanOp::Union);
+    let pocket =
+        move || made(make_box([0.0; 3], [40.0, 30.0, 10.0]).unwrap(), make_box([10.0, 10.0, 5.0], [20.0, 10.0, 6.0]).unwrap(), BooleanOp::Subtract);
+    const BASE: [[f64; 3]; 4] = [[20.0, 10.0, 10.0], [25.0, 15.0, 10.0], [20.0, 20.0, 10.0], [15.0, 15.0, 10.0]];
+    const RIM: [[f64; 3]; 4] = [[20.0, 10.0, 5.0], [30.0, 15.0, 5.0], [20.0, 20.0, 5.0], [10.0, 15.0, 5.0]];
+    let r = 1.0;
+    let rounded =
+        move |body: Body, at: [[f64; 3]; 4], turn, sizes: [f64; 4]| blend_dropping(&body, Blend::Round, turn, &at, &sizes, 0.1).map(|(b, _)| b);
+    // solidcore's tori, and the record's kinds of surface: its torus is a ring torus, so a horn
+    // torus's face there is its exact rational form.
+    let measured = |b: &Body| {
+        use solidcore::surface::surface::p2::SurfaceKind;
+        let (rec, _) = native(&to_arrays(b).unwrap()).unwrap();
+        rec.validate().unwrap();
+        let mut tori = Vec::new();
+        {
+            let g = b.0.lock().unwrap();
+            for f in solidcore::query::api_queries::get_faces(&g).unwrap() {
+                if let Some(s) = solidcore::topology::face::p2::surface(&g, f).unwrap()
+                    && let SurfaceKind::Torus(t) = s.kind()
+                {
+                    tori.push((t.major_radius(), t.minor_radius()));
+                }
+            }
+        }
+        (volume(b, 1e-10).unwrap(), counts(b).unwrap()[0], tori, kinds(&rec))
+    };
+    let (mitre, swept) =
+        timed("turn", move || (rounded(boss(), BASE, Turn::Mitre, [r; 4]).unwrap(), rounded(boss(), BASE, Turn::Swept, [r; 4]).unwrap()));
+    let (vm, fm, tm, km) = measured(&mitre);
+    let (vs, fs, ts, ks) = measured(&swept);
+    println!("mitre: {vm:.9}, {fm} faces {km:?}; swept: {vs:.9}, {fs} faces {ks:?}, tori {ts:?}");
+    let (a, m) = (spandrel(r), (5.0 / 6.0 - PI / 4.0) * r * r * r);
+    let base = 12500.0 + 40.0 * a;
+    assert!(rel(vm, base + 8.0 * m) < 1e-9, "mitre {vm} vs {}", base + 8.0 * m);
+    assert!(rel(vs, base + 2.0 * PI * m) < 1e-9, "swept {vs} vs {}", base + 2.0 * PI * m);
+    assert_eq!((fm, tm.len(), km.get("rational_spline")), (15, 0, None));
+    assert_eq!((fs, ts.len(), ks.get("rational_spline")), (19, 4, Some(&4)));
+    assert!(ts.iter().all(|(major, minor)| (major - r).abs() < 1e-12 && (minor - r).abs() < 1e-12), "{ts:?}");
+    // Swept is for rounds only.
+    assert_eq!(blend_dropping(&boss(), Blend::Chamfer, Turn::Swept, &BASE, &[r; 4], 0.1).err(), Some(Error::Argument));
+    let unequal = timed("turn unequal", move || rounded(boss(), BASE, Turn::Swept, [1.0, 1.5, 1.0, 1.5]).err());
+    let rim = timed("turn rim", move || rounded(pocket(), RIM, Turn::Swept, [r; 4]).err());
+    println!("unequal: {unequal:?}\nrim: {rim:?}");
+    assert!(
+        matches!(&unequal, Some(Error::TurnRefused { room: false, why, at: Some(_) }) if why.starts_with("a swept turn is built between constant rounds of one radius")),
+        "{unequal:?}"
+    );
+    assert!(
+        matches!(&rim, Some(Error::TurnRefused { room: true, why, at: Some(_) }) if why.contains("round that edge at a radius of at least 1 first")),
+        "{rim:?}"
+    );
+}
+
 /// Solidcore alone: edge attributes across a cliff overflow. A 40 x 30 x 10 block notched below its
 /// top at (40, 0), its front and right top edges rounded r8 (their rails run off over the notch).
 /// The back and left top edges are each trimmed 8 by those rounds: (0, 30)-(32, 30) and (0, 8)-(0, 30)

crates/smlib/src/lib.rs

@@ -19,14 +19,13 @@ pub mod pcurves;
 mod sheets;
 mod split;
 pub mod ssi;
-pub mod stop;
 pub mod sweeps;
 pub mod trace;
 pub mod trim;
 
 pub use check::{CheckLevel, CheckReport};
 pub use measure::{MEASURE_ACCURACY, MassProperties, PointClass};
-pub use ops::{Blend, BooleanOp, ChamferSecond, Hole, HoleEdge, MAX_POINTS, MAX_UNION_BREPS};
+pub use ops::{Blend, BooleanOp, ChamferSecond, Hole, HoleEdge, MAX_POINTS, MAX_UNION_BREPS, Turn};
 
 /// Why an SMLib call failed.
 #[derive(Clone, Debug, PartialEq)]
@@ -62,6 +61,11 @@ pub enum Error {
     Unsupported,
     /// A blend's edges meet at a vertex of a kind no SMLib blend corner handles yet.
     CornerUnsupported,
+    /// A swept turn ([`Turn::Swept`]) solidcore does not build at the corner `at`: `room` where
+    /// no radius builds it (a sharp concave side edge between the rounds, solidcore's `NoRoom`),
+    /// else not supported there (`CornerUnsupported`: unequal or variable rounds, a corner of
+    /// four edges, a curved, drafted or tangent side edge); `why` is solidcore's reason.
+    TurnRefused { room: bool, why: String, at: Option<[f64; 3]> },
     /// SMLib does not set back the corner of corner point `corner`: SMLib sets back a corner
     /// only where every edge meeting it is blended and they are all convex or all concave.
     CornerRefused { corner: usize },
@@ -193,6 +197,13 @@ impl std::fmt::Display for Error {
             }
             Error::Unsupported => write!(f, "not supported yet: SMLib cannot build this exactly"),
             Error::CornerUnsupported => write!(f, "not supported yet: a corner of this kind is not supported yet by SMLib's blends"),
+            Error::TurnRefused { why, at, .. } => {
+                write!(f, "the swept corner is not built")?;
+                if let Some([x, y, z]) = at {
+                    write!(f, " at ({x:.3}, {y:.3}, {z:.3})")?;
+                }
+                write!(f, ": {why}")
+            }
             Error::CornerRefused { corner } => write!(
                 f,
                 "not supported yet: SMLib does not set back corner {}: it sets back a corner only where every edge meeting it is blended, all convex or all concave",
@@ -233,13 +244,6 @@ pub fn current_call() -> Option<String> {
     core::dump::current()
 }
 
-/// Keeps one of the kernels calls run on out of use until dropped: the next calls run on another.
-/// For tests of what happens when a design's bodies come from a kernel that is busy elsewhere.
-#[doc(hidden)]
-pub fn hold_a_kernel() -> core::HeldKernel {
-    core::hold_a_kernel()
-}
-
 /// Is this thread inside a solidcore call? A panic there is caught and becomes
 /// [`Error::Internal`]; crash reports mark it recovered.
 pub fn in_call() -> bool {

crates/smlib/src/ops.rs

@@ -58,6 +58,30 @@ impl Blend {
     }
 }
 
+/// How two constant rounds of one radius turn round a sharp, straight, convex side edge square to
+/// both on a plane (the rounds along a boss's base, at its upright edges): the turn of
+/// [`Brep::blend_dropping`]'s rounds ([`Blend::Round`] only).
+#[derive(Clone, Copy, Debug, Default, PartialEq, Eq)]
+pub enum Turn {
+    /// The rounds run on to where they cross and meet in a mitre, the plane section of the two.
+    #[default]
+    Mitre,
+    /// The rounds end on their sections at the side edge, and the corner's face is that section
+    /// revolved about the side edge, an exact torus tangent to both rounds. A corner where this
+    /// is not built is [`Error::TurnRefused`].
+    Swept,
+}
+
+impl Turn {
+    /// The turn's name in a trace ([`crate::trace`]).
+    pub fn word(self) -> &'static str {
+        match self {
+            Turn::Mitre => "mitre",
+            Turn::Swept => "swept",
+        }
+    }
+}
+
 /// The second side of [`Brep::chamfer_sides`].
 #[derive(Clone, Copy, Debug, PartialEq)]
 pub enum ChamferSecond {
@@ -172,18 +196,19 @@ impl Brep {
 
     /// [`Brep::blend`], with whether each point picked an edge that a larger round, overflowing
     /// its faces, removed whole: that edge is gone and not rounded (SMLib rounds the edges whose
-    /// blends overflow first, then what is left of the others).
-    pub fn blend_dropping(&self, kind: Blend, edges: &[[f64; 3]], sizes: &[f64], tolerance: f64) -> Result<(Brep, Vec<bool>)> {
+    /// blends overflow first, then what is left of the others). Two rounds turn at a side edge as
+    /// `turn` says; [`Turn::Swept`] is for [`Blend::Round`] only ([`Error::Argument`] otherwise).
+    pub fn blend_dropping(&self, kind: Blend, turn: Turn, edges: &[[f64; 3]], sizes: &[f64], tolerance: f64) -> Result<(Brep, Vec<bool>)> {
         if edges.len() > MAX_POINTS || edges.is_empty() || sizes.len() != edges.len() {
             return Err(Error::Argument);
         }
-        let r = core::blend::blend_dropping(self.core(), kind, edges, sizes, tolerance).map(|(b, d)| (Brep::made_core(b), d));
+        let r = core::blend::blend_dropping(self.core(), kind, turn, edges, sizes, tolerance).map(|(b, d)| (Brep::made_core(b), d));
         trace::call(
             "blend_dropping",
             &[self],
             &r,
             |(b, _)| vec![b.id],
-            || json!({"kind": kind.word(), "edges": trace::picks(self, PickKind::Edge, edges, tolerance), "sizes": sizes}),
+            || json!({"kind": kind.word(), "turn": turn.word(), "edges": trace::picks(self, PickKind::Edge, edges, tolerance), "sizes": sizes}),
         );
         r
     }

crates/smlib/src/ssi.rs

@@ -129,7 +129,7 @@ impl Spec {
 impl Surface {
     /// solidcore's surface, made the first time it is needed.
     fn core(&self) -> Result<&crate::core::split::Tool> {
-        self.core.get_or_init(|| crate::stop::unstoppable(|| crate::core::ssi::surface(&self.spec))).as_ref().map_err(Clone::clone)
+        self.core.get_or_init(|| crate::core::ssi::surface(&self.spec)).as_ref().map_err(Clone::clone)
     }
 
     pub(crate) fn spec(&self) -> &Spec {

crates/smlib/src/stop.rs

@@ -1,71 +0,0 @@
-//! Stopping the kernel calls of work nobody waits for any more: the jobs of a design that closed.
-//! Work runs [`Stop::within`] its design's token; once the token is stopped, each operation under
-//! it refuses to start, and one running stops when solidcore next checks ([`solidcore::kernel::Kernel::cancel`]).
-//!
-//! A stopped operation is an error like any other, and the caller's bodies are as they were: only
-//! operations that build on copies stop. Calls that answer from a body itself ([`crate::core::with_body`],
-//! measuring, say) always run to their end, since solidcore may leave what a stopped call borrows
-//! half-changed.
-
-use std::cell::RefCell;
-
-use solidcore::kernel::CancelToken;
-
-thread_local! {
-    static CURRENT: RefCell<Option<Stop>> = const { RefCell::new(None) };
-}
-
-/// Stops the kernel work running under it, on every thread it reached.
-#[derive(Clone, Debug, Default)]
-pub struct Stop(CancelToken);
-
-impl Stop {
-    pub fn new() -> Stop {
-        Stop::default()
-    }
-
-    /// Stop the work under this token, now and from now on.
-    pub fn stop(&self) {
-        self.0.cancel();
-    }
-
-    pub fn is_stopped(&self) -> bool {
-        self.0.is_cancelled()
-    }
-
-    /// Run `f` with this token over the kernel work it does on this thread.
-    pub fn within<R>(&self, f: impl FnOnce() -> R) -> R {
-        scoped(Some(self.clone()), f)
-    }
-}
-
-/// The token over this thread's work, to hand to the worker threads it starts.
-pub fn current() -> Option<Stop> {
-    CURRENT.with(|c| c.borrow().clone())
-}
-
-/// Run `f` under `stop` (`None`: under none), as [`current`] was on the thread that started it.
-pub fn scoped<R>(stop: Option<Stop>, f: impl FnOnce() -> R) -> R {
-    let previous = CURRENT.with(|c| c.replace(stop));
-    struct Restore(Option<Option<Stop>>);
-    impl Drop for Restore {
-        fn drop(&mut self) {
-            if let Some(previous) = self.0.take() {
-                CURRENT.with(|c| *c.borrow_mut() = previous);
-            }
-        }
-    }
-    let _restore = Restore(Some(previous));
-    f()
-}
-
-/// Run `f` so that no token stops it: for what fills a cell every later user of a body reads,
-/// which must not keep a stopped job's error.
-pub fn unstoppable<R>(f: impl FnOnce() -> R) -> R {
-    scoped(None, f)
-}
-
-/// solidcore's token of the work on this thread.
-pub(crate) fn token() -> Option<CancelToken> {
-    CURRENT.with(|c| c.borrow().as_ref().map(|s| s.0.clone()))
-}

crates/smlib/src/tests.rs

@@ -78,7 +78,7 @@ fn calls_from_many_threads_are_serialised() {
 static DUMP_DIR_TESTS: std::sync::Mutex<()> = std::sync::Mutex::new(());
 
 /// Entry points that ask no kernel, so have nothing to say here.
-const NO_KERNEL: [&str; 14] = [
+const NO_KERNEL: [&str; 13] = [
     "inertia_tensor",
     "is_valid",
     "failed_tests",
@@ -92,7 +92,6 @@ const NO_KERNEL: [&str; 14] = [
     "word",
     "words",
     "in_call",
-    "hold_a_kernel",
 ];
 
 const ANSWERING: [&str; 63] = [
@@ -192,7 +191,7 @@ fn every_entry_point_is_in_the_guard() {
 fn every_entry_point_answers() {
     use crate::sweeps::{Affine, Curve, DraftCorner, Ends, SweepFrame};
     use crate::trim::{Continuation, Holes};
-    use crate::{Blend, BooleanOp, ChamferSecond, CheckLevel};
+    use crate::{Blend, BooleanOp, ChamferSecond, CheckLevel, Turn};
     fn says<T>(_name: &str, r: Result<T>) -> Option<T> {
         r.ok()
     }
@@ -223,7 +222,7 @@ fn every_entry_point_answers() {
     says("fillet", a.fillet(&edge, 0.1, 1.0));
     says("chamfer", a.chamfer(&edge, 0.1, 1.0));
     says("blend", a.blend(Blend::Round, &edge, &[1.0], 0.1));
-    says("blend_dropping", a.blend_dropping(Blend::Round, &edge, &[1.0], 0.1));
+    says("blend_dropping", a.blend_dropping(Blend::Round, Turn::Mitre, &edge, &[1.0], 0.1));
     let corner = [p(10.0, 10.0, 10.0)];
     let three = [p(5.0, 10.0, 10.0), p(10.0, 5.0, 10.0), p(10.0, 10.0, 5.0)];
     says("blend_setback", a.blend_setback(Blend::Round, &three, &[1.0; 3], &corner, &[2.0], 0.1));
@@ -511,82 +510,3 @@ fn a_panic_beside_a_running_call_costs_only_its_own_kernel() {
     release.send(()).unwrap();
     held.join().unwrap().unwrap();
 }
-
-/// A stuck call keeps its kernel and nothing more: the pool never holds more than its limit of
-/// idle kernels however many calls ran side by side, and once as many calls as it allows are
-/// stuck, a new call is refused rather than growing it or waiting.
-#[test]
-fn the_kernel_pool_stays_bounded_when_calls_stick() {
-    let mut pool = core::Pool { idle: Vec::new(), running: 0, most_idle: 1, most_running: 3 };
-    let mut made = 0;
-    let mut make = || {
-        made += 1;
-        made
-    };
-    let (a, b, c) = (pool.take(&mut make), pool.take(&mut make), pool.take(&mut make));
-    assert_eq!((a, b, c), (Some(1), Some(2), Some(3)), "side by side, each on its own");
-    assert_eq!(pool.take(&mut make), None, "refused, not waiting, not one more");
-    pool.put(a);
-    assert_eq!(pool.take(&mut make), Some(1), "room again, its kernel used again");
-    // The other two never come back here: they still count, and hold no idle slot.
-    pool.put(Some(1));
-    pool.put(b);
-    assert_eq!(pool.idle, [1], "no more idle than allowed");
-    assert_eq!(pool.running, 1, "one still stuck");
-    // A stopped call's kernel is not used again.
-    pool.put(None);
-    assert_eq!(pool.running, 0);
-    assert_eq!(pool.idle, [1]);
-}
-
-/// A stop reaches a running call at solidcore's next check and later calls before they start;
-/// the kernel it ran on is not used again; calls of other work and answers from a body go on.
-#[test]
-fn a_stopped_call_ends_at_its_next_check_and_holds_up_nothing() {
-    let stop = stop::Stop::new();
-    let (started, is_started) = std::sync::mpsc::channel();
-    let running = {
-        let stop = stop.clone();
-        std::thread::spawn(move || {
-            stop.within(|| {
-                let first: Result<()> = core::run("stopped_call", |k| {
-                    let _ = started.send(());
-                    // A long solidcore loop, until it is stopped.
-                    loop {
-                        k.check_cancelled("stopped_call")?;
-                        std::thread::yield_now();
-                    }
-                });
-                let next = Brep::make_box([0.0; 3], [1.0; 3]);
-                (first, next.map(|_| ()))
-            })
-        })
-    };
-    is_started.recv().unwrap();
-    let body = answered(|| Brep::make_box([0.0; 3], [10.0; 3]).unwrap());
-    stop.stop();
-    let (first, next) = answered(move || running.join().unwrap());
-    assert!(first.is_err_and(|e| e.to_string().contains("cancel")));
-    assert!(next.is_err_and(|e| e.to_string().contains("cancelled")), "refused before it starts");
-    // Under a stopped token, a body still answers, and is as it was.
-    let v = stop.within(|| body.volume(1e-7)).unwrap();
-    assert!((v - 1000.0).abs() < 1e-6, "{v}");
-    assert!(stop.within(|| body.boolean(&body, BooleanOp::Union)).is_err(), "an operation is refused");
-    // What fills a shared cell is not stopped.
-    assert!(stop.within(|| stop::unstoppable(|| Brep::make_box([0.0; 3], [1.0; 3]))).is_ok());
-    // And nothing else is affected.
-    let v = body.boolean(&body, BooleanOp::Union).unwrap().unwrap().volume(1e-7).unwrap();
-    assert!((v - 1000.0).abs() < 1e-6, "{v}");
-}
-
-/// Every call starts with the same draws of random rays, whatever its kernel did before: what
-/// depends on them answers the same on any kernel of the pool.
-#[test]
-fn every_call_starts_clean_on_any_kernel() {
-    let draw = |k: &mut solidcore::kernel::Kernel| Ok(k.rng.next_f64());
-    let first = core::run("draw", draw).unwrap();
-    assert_eq!(core::run("draw", draw).unwrap(), first, "the same kernel, later");
-    let held = hold_a_kernel();
-    assert_eq!(core::run("draw", draw).unwrap(), first, "another kernel");
-    drop(held);
-}

crates/ui-egui/src/agent_chat/markdown_view.rs

@@ -6,6 +6,7 @@
 //! changes.
 
 use crate::fonts::RichTextExt as _;
+use crate::ui_kit::BackingTooltipExt as _;
 use std::hash::{Hash, Hasher};
 use std::sync::Arc;
 
@@ -70,7 +71,7 @@ fn spans(ui: &mut egui::Ui, spans: &[Span], size: f32, color: Color32) {
             for (label, url) in links {
                 // The text above already shows the label; the button says where it goes.
                 let to = format!("↗ {}", host(url));
-                ui.hyperlink_to(RichText::new(to).size(size - (t.font_button - t.font_body)), url).on_hover_text(format!("{label}: {url}"));
+                ui.hyperlink_to(RichText::new(to).size(size - (t.font_button - t.font_body)), url).backing_on_hover_text(format!("{label}: {url}"));
             }
         });
     }
@@ -94,17 +95,21 @@ pub fn show(ui: &mut egui::Ui, slot: usize, src: &str) {
                 ui.add(egui::Label::new(RichText::new(markdown::plain(s)).size(size).semibold().color(t.text)).selectable(true).wrap());
             }
             Block::Code { text, .. } => {
-                egui::Frame::NONE.fill(t.field).corner_radius(t.radius_sm).inner_margin(Margin::same(6)).show(ui, |ui| {
-                    ui.set_width(ui.available_width());
-                    ui.add(
-                        egui::Label::new(RichText::new(text).monospace().size(size - (t.font_button - t.font_body)).color(t.text))
-                            .selectable(true)
-                            .wrap(),
-                    );
-                    if crate::ui_kit::button(ui, tr("ui.agent_chat_copy"), crate::ui_kit::Button::Small).clicked() {
-                        ui.ctx().copy_text(text.clone());
-                    }
-                });
+                crate::ui_kit::Container::show_backing(
+                    ui,
+                    egui::Frame::NONE.fill(t.field).corner_radius(t.radius_sm).inner_margin(Margin::same(6)),
+                    |ui| {
+                        ui.set_width(ui.available_width());
+                        ui.add(
+                            egui::Label::new(RichText::new(text).monospace().size(size - (t.font_button - t.font_body)).color(t.text))
+                                .selectable(true)
+                                .wrap(),
+                        );
+                        if crate::ui_kit::button(ui, tr("ui.agent_chat_copy"), crate::ui_kit::Button::Small).clicked() {
+                            ui.ctx().copy_text(text.clone());
+                        }
+                    },
+                );
             }
             Block::List { ordered, start, items } => {
                 for (i, item) in items.iter().enumerate() {

crates/ui-egui/src/agent_chat/panel.rs

@@ -3,6 +3,7 @@
 //! width and fold are preferences, so they come back next time.
 
 use crate::fonts::RichTextExt as _;
+use crate::ui_kit::BackingTooltipExt as _;
 use crate::ui_kit::{Container, Edge, Surface};
 use egui::{Align, Align2, Color32, Id, Layout, Rect, RichText, Sense, Stroke, pos2, vec2};
 
@@ -379,7 +380,7 @@ fn context_chips(ui: &mut egui::Ui, context: &Context, removable: bool) -> Optio
                                 })
                                 .response;
                             if !item.detail.is_empty() {
-                                chip.on_hover_text(&item.detail);
+                                chip.backing_on_hover_text(&item.detail);
                             }
                         }
                     }
@@ -425,7 +426,7 @@ fn picture_strip(ui: &mut egui::Ui, n: usize, pictures: &[Picture]) -> Option<us
             let thumb = ui.add(egui::Image::new((texture.id(), size)).corner_radius(t.radius_sm).sense(Sense::click()));
             crate::scenario::publish_handle(&format!("agent_chat:picture:{n}:{i}"), thumb.rect.center());
             let hover_max = (ui.ctx().content_rect().size() * 0.5).min(vec2(PREVIEW_MAX.0, PREVIEW_MAX.1));
-            let thumb = thumb.on_hover_cursor(egui::CursorIcon::PointingHand).on_hover_ui(|ui| {
+            let thumb = thumb.on_hover_cursor(egui::CursorIcon::PointingHand).backing_on_hover_ui(|ui| {
                 ui.add(egui::Image::new((texture.id(), fit(texture.size_vec2(), hover_max))).corner_radius(t.radius_sm));
                 if !picture.note.is_empty() {
                     ui.label(&picture.note);
@@ -583,7 +584,8 @@ fn window(app: &mut SolveApp, ctx: &egui::Context) {
         }
         let t = Tokens::get();
         let frame = Container::new(ui.ctx(), Surface::Panel).edge_frame(t.dialog_body);
-        let r = Container::new(ui.ctx(), Surface::Viewport).central().frame(frame).show(ui, |ui| ui_kit::scope(ui, |ui| body(app, ui, false)));
+        let panel = Container::new(ui.ctx(), Surface::Viewport).central();
+        let r = Container::show_central(ui, panel, frame, |ui| ui_kit::scope(ui, |ui| body(app, ui, false)));
         // The picture viewer opens over this window, where the click was, not over the main one.
         gallery_window(app, ui.ctx());
         if class == egui::ViewportClass::EmbeddedWindow {
@@ -672,7 +674,7 @@ fn glyph_button(ui: &mut egui::Ui, kind: &str, tip: &str) -> egui::Response {
     }
     crate::scenario::publish_rect(&format!("agent_chat:{kind}"), r);
     crate::scenario::publish_handle(&format!("agent_chat:{kind}"), r.center());
-    resp.on_hover_text(tip)
+    resp.backing_on_hover_text(tip)
 }
 
 fn state_color(state: State) -> Color32 {
@@ -715,7 +717,7 @@ fn strip(app: &mut SolveApp, ui: &mut egui::Ui) {
         t.primary_border(t.border),
     );
     let tip = format!("{} · {}", tip(app), state.label());
-    if resp.on_hover_text(tip).clicked() {
+    if resp.backing_on_hover_text(tip).clicked() {
         app.preferences.agent_chat_minimized = false;
     }
 }
@@ -967,7 +969,7 @@ fn desktop_body(app: &mut SolveApp, ui: &mut egui::Ui) {
                                 )
                             })
                             .inner;
-                        let permissions = permissions.on_hover_text(mode.label());
+                        let permissions = permissions.backing_on_hover_text(mode.label());
                         crate::scenario::publish_rect("agent_chat:permissions", permissions.rect);
                         crate::scenario::publish_handle("agent_chat:permissions", permissions.rect.center());
                         // A message waits for files still being read.
@@ -1004,8 +1006,8 @@ fn desktop_body(app: &mut SolveApp, ui: &mut egui::Ui) {
                         let attach = ui
                             .add_enabled_ui(images, |ui| ui_kit::checkbox(ui, tr("ui.agent_chat_attach_view"), &mut app.agent_chat.attach_view))
                             .inner
-                            .on_hover_text(tr("ui.agent_chat_attach_view_tip"))
-                            .on_disabled_hover_text(tr("ui.agent_chat_no_images"));
+                            .backing_on_hover_text(tr("ui.agent_chat_attach_view_tip"))
+                            .backing_on_disabled_hover_text(tr("ui.agent_chat_no_images"));
                         crate::scenario::publish_handle("agent_chat:attach", attach.rect.center());
                         // What is selected in the model goes with the message: text for the agent,
                         // chips in the conversation.
@@ -1016,11 +1018,11 @@ fn desktop_body(app: &mut SolveApp, ui: &mut egui::Ui) {
                             tr("ui.agent_chat_attach_selection").to_string()
                         };
                         let pick = ui_kit::checkbox(ui, &label, &mut app.agent_chat.attach_selection)
-                            .on_hover_text(tr("ui.agent_chat_attach_selection_tip"));
+                            .backing_on_hover_text(tr("ui.agent_chat_attach_selection_tip"));
                         crate::scenario::publish_handle("agent_chat:attach_selection", pick.rect.center());
                         // Choose faces, edges, features and bodies on purpose, then OK.
                         let picker = ui_kit::button(ui, tr("ui.agent_chat_pick_context"), ui_kit::Button::Enabled(app.dialog.is_none()))
-                            .on_hover_text(tr("ui.agent_chat_pick_context_tip"));
+                            .backing_on_hover_text(tr("ui.agent_chat_pick_context_tip"));
                         crate::scenario::publish_handle("agent_chat:pick_context", picker.rect.center());
                         pick_clicked = picker.clicked();
                         if let Some(turn) = &app.agent_chat.turn {
@@ -1101,7 +1103,7 @@ fn switcher(app: &mut SolveApp, ui: &mut egui::Ui) {
                 ui_kit::dropdown_menu(ui, "sc_agent_switch", &label, |ui| {
                     for e in &all {
                         let sel = current.as_ref().is_some_and(|c| c.id == e.id);
-                        let r = ui_kit::list_picker(ui, &e.id, &e.name, sel).on_hover_text(format!("{} {}", e.detail(), e.login));
+                        let r = ui_kit::list_picker(ui, &e.id, &e.name, sel).backing_on_hover_text(format!("{} {}", e.detail(), e.login));
                         crate::scenario::publish_handle(&format!("agent_chat:agent:{}", e.id), r.rect.center());
                         if r.clicked() {
                             picked = Some(e.id.clone());
@@ -1119,7 +1121,7 @@ fn switcher(app: &mut SolveApp, ui: &mut egui::Ui) {
             .inner;
         crate::scenario::publish_rect("agent_chat:switcher", combo.rect);
         crate::scenario::publish_handle("agent_chat:switcher", combo.rect.center());
-        combo.on_hover_text(tr("ui.ai_switch_tip"));
+        combo.backing_on_hover_text(tr("ui.ai_switch_tip"));
         if add {
             super::settings::open_add(app);
         }
@@ -1148,7 +1150,7 @@ fn switcher(app: &mut SolveApp, ui: &mut egui::Ui) {
                 .inner;
             crate::scenario::publish_rect("agent_chat:mode", r.rect);
             crate::scenario::publish_handle("agent_chat:mode", r.rect.center());
-            r.on_hover_text(tr("ui.ai_agent_mode_tip"));
+            r.backing_on_hover_text(tr("ui.ai_agent_mode_tip"));
             if let Some(m) = pick {
                 set_mode(app, &m);
             }
@@ -1187,7 +1189,7 @@ fn switcher(app: &mut SolveApp, ui: &mut egui::Ui) {
                     )
                 })
                 .inner;
-            picker.response.on_hover_text(tr("ui.agent_chat_model_tip"));
+            picker.response.backing_on_hover_text(tr("ui.agent_chat_model_tip"));
             match picker.inner {
                 Some(ui_kit::Picked::Listed(m)) => set_model(app, &m),
                 Some(ui_kit::Picked::Custom(m)) => {
@@ -1205,7 +1207,7 @@ fn switcher(app: &mut SolveApp, ui: &mut egui::Ui) {
     }
     ui.horizontal(|ui| {
         let b = if app.agent_chat.state().running() {
-            ui_kit::button(ui, tr("ui.agent_chat_stop"), ui_kit::Button::Normal).on_hover_text(tr("ui.agent_chat_stop_tip"))
+            ui_kit::button(ui, tr("ui.agent_chat_stop"), ui_kit::Button::Normal).backing_on_hover_text(tr("ui.agent_chat_stop_tip"))
         } else {
             let label = if app.agent_chat.state() == State::Failed { "ui.agent_chat_retry" } else { "ui.agent_chat_connect" };
             ui_kit::button(ui, tr(label), ui_kit::Button::Normal)
@@ -1372,11 +1374,11 @@ fn config_select(app: &mut SolveApp, ui: &mut egui::Ui, option: &acp::ConfigOpti
                             if let Some(group) = group
                                 && previous_group != Some(group)
                             {
-                                ui.label(RichText::new(compact_text(group, 32)).color(t.text_dim).size(t.font_small)).on_hover_text(group);
+                                ui.label(RichText::new(compact_text(group, 32)).color(t.text_dim).size(t.font_small)).backing_on_hover_text(group);
                             }
                             previous_group = group;
                             let row = ui_kit::list_picker(ui, &choice.value, &compact_text(&choice.name, 32), choice.value == option.current_value);
-                            let row = row.on_hover_text(
+                            let row = row.backing_on_hover_text(
                                 [choice.name.as_str(), choice.description.as_str()]
                                     .into_iter()
                                     .filter(|part| !part.is_empty())
@@ -1400,7 +1402,7 @@ fn config_select(app: &mut SolveApp, ui: &mut egui::Ui, option: &acp::ConfigOpti
         response
     };
     response.widget_info(|| egui::WidgetInfo::labeled(egui::WidgetType::ComboBox, enabled, format!("{name}: {selected}")));
-    response.on_hover_text(tip);
+    response.backing_on_hover_text(tip);
     match picked {
         Some(ui_kit::Picked::Listed(value)) => super::set_config_option(app, &option.id, &value),
         Some(ui_kit::Picked::Custom(value)) => {
@@ -1556,7 +1558,7 @@ fn agent_list(app: &mut SolveApp, ui: &mut egui::Ui) {
     }
     for e in &all {
         let selected = current.as_ref().is_some_and(|c| c.id == e.id);
-        let resp = ui_kit::list_picker(ui, &e.id, &e.name, selected).on_hover_text(format!("{} {}", e.detail(), e.login));
+        let resp = ui_kit::list_picker(ui, &e.id, &e.name, selected).backing_on_hover_text(format!("{} {}", e.detail(), e.login));
         crate::scenario::publish_handle(&format!("agent_chat:pick:{}", e.id), resp.rect.center());
         if resp.clicked() {
             app.agent_chat.agent_id = Some(e.id.clone());
@@ -1575,7 +1577,7 @@ fn agent_list(app: &mut SolveApp, ui: &mut egui::Ui) {
             for m in missing {
                 ui.horizontal(|ui| {
                     ui_kit::text(ui, m.name, ui_kit::Text::Inline);
-                    if ui_kit::button(ui, tr("ui.agent_chat_copy"), ui_kit::Button::Small).on_hover_text(m.install).clicked() {
+                    if ui_kit::button(ui, tr("ui.agent_chat_copy"), ui_kit::Button::Small).backing_on_hover_text(m.install).clicked() {
                         ui.ctx().copy_text(m.install.to_string());
                     }
                 });
@@ -1812,7 +1814,7 @@ fn conversation(app: &mut SolveApp, ui: &mut egui::Ui) {
                             ui_kit::assistant_actions(ui, |ui| {
                                 let allow = ui_kit::primary_button(ui, tr("ui.agent_chat_allow_once"));
                                 let always = ui_kit::button(ui, tr("ui.ai_always_allow"), ui_kit::Button::Normal)
-                                    .on_hover_text(trf("ui.ai_always_allow_tip", &[("tool", tool)]));
+                                    .backing_on_hover_text(trf("ui.ai_always_allow_tip", &[("tool", tool)]));
                                 let deny = ui
                                     .with_layout(Layout::left_to_right(Align::Center), |ui| {
                                         ui_kit::button(ui, tr("ui.agent_chat_deny"), ui_kit::Button::Normal)
@@ -1842,7 +1844,8 @@ fn conversation(app: &mut SolveApp, ui: &mut egui::Ui) {
                     if *undone {
                         ui.label(RichText::new(tr("ui.agent_chat_undone")).color(t.text_dim).size(crate::theme::Tokens::get().font_caption));
                     } else if Arc::ptr_eq(doc, &current_doc) {
-                        let b = ui_kit::button(ui, tr("ui.agent_chat_undo_changes"), ui_kit::Button::Normal).on_hover_text(tr("ui.ai_undo_tip"));
+                        let b =
+                            ui_kit::button(ui, tr("ui.agent_chat_undo_changes"), ui_kit::Button::Normal).backing_on_hover_text(tr("ui.ai_undo_tip"));
                         crate::scenario::publish_handle("agent_chat:undo", b.rect.center());
                         if b.clicked() {
                             undo = Some(n);
@@ -1867,61 +1870,62 @@ fn conversation(app: &mut SolveApp, ui: &mut egui::Ui) {
     let mut edit_buf = editing.as_ref().map(|(_, b)| b.clone());
     for (n, p) in app.agent_chat.pending.iter().enumerate() {
         ui.add_space(6.0);
-        Container::new(ui.ctx(), Surface::Panel)
+        let frame = Container::new(ui.ctx(), Surface::Panel)
             .edge_frame(t.panel)
             .stroke(Stroke::new(1.0, t.accent))
             .corner_radius(t.control_radius)
-            .inner_margin(egui::Margin::same(6))
-            .show(ui, |ui| {
-                ui.set_width(ui.available_width());
-                ui.horizontal(|ui| {
-                    let tag = if stopped && !busy { "ui.agent_chat_queued_stopped" } else { "ui.agent_chat_queued" };
-                    ui.label(RichText::new(tr(tag)).color(t.accent).semibold().size(crate::theme::Tokens::get().font_small));
-                    ui.with_layout(Layout::right_to_left(Align::Center), |ui| {
-                        let x = ui_kit::button(ui, "×", ui_kit::Button::Small).on_hover_text(tr("ui.agent_chat_remove"));
-                        crate::scenario::publish_handle(&format!("agent_chat:pending_remove:{n}"), x.rect.center());
-                        if x.clicked() {
-                            remove = Some(n);
+            .inner_margin(egui::Margin::same(6));
+        Container::show_backing(ui, frame, |ui| {
+            ui.set_width(ui.available_width());
+            ui.horizontal(|ui| {
+                let tag = if stopped && !busy { "ui.agent_chat_queued_stopped" } else { "ui.agent_chat_queued" };
+                ui.label(RichText::new(tr(tag)).color(t.accent).semibold().size(crate::theme::Tokens::get().font_small));
+                ui.with_layout(Layout::right_to_left(Align::Center), |ui| {
+                    let x = ui_kit::button(ui, "×", ui_kit::Button::Small).backing_on_hover_text(tr("ui.agent_chat_remove"));
+                    crate::scenario::publish_handle(&format!("agent_chat:pending_remove:{n}"), x.rect.center());
+                    if x.clicked() {
+                        remove = Some(n);
+                    }
+                    if editing.as_ref().is_none_or(|(i, _)| *i != n) {
+                        let e = ui_kit::button(ui, tr("ui.agent_chat_edit"), ui_kit::Button::Small);
+                        crate::scenario::publish_handle(&format!("agent_chat:pending_edit:{n}"), e.rect.center());
+                        if e.clicked() {
+                            start_edit = Some((n, p.text.clone()));
                         }
-                        if editing.as_ref().is_none_or(|(i, _)| *i != n) {
-                            let e = ui_kit::button(ui, tr("ui.agent_chat_edit"), ui_kit::Button::Small);
-                            crate::scenario::publish_handle(&format!("agent_chat:pending_edit:{n}"), e.rect.center());
-                            if e.clicked() {
-                                start_edit = Some((n, p.text.clone()));
-                            }
+                    }
+                });
+            });
+            match (&editing, edit_buf.as_mut()) {
+                (Some((i, _)), Some(buf)) if *i == n => {
+                    let te = ui_kit::message_field(ui, Id::new(("sc_agent_pending_input", n)), buf, "");
+                    crate::scenario::publish_rect("agent_chat:pending_input", te.rect);
+                    ui.horizontal(|ui| {
+                        if ui_kit::button(ui, tr("ui.agent_chat_save"), ui_kit::Button::Normal).clicked() {
+                            edit_done = Some((n, Some(buf.clone())));
+                        }
+                        if ui_kit::button(ui, tr("ui.agent_chat_cancel"), ui_kit::Button::Normal).clicked() {
+                            edit_done = Some((n, None));
                         }
                     });
-                });
-                match (&editing, edit_buf.as_mut()) {
-                    (Some((i, _)), Some(buf)) if *i == n => {
-                        let te = ui_kit::message_field(ui, Id::new(("sc_agent_pending_input", n)), buf, "");
-                        crate::scenario::publish_rect("agent_chat:pending_input", te.rect);
-                        ui.horizontal(|ui| {
-                            if ui_kit::button(ui, tr("ui.agent_chat_save"), ui_kit::Button::Normal).clicked() {
-                                edit_done = Some((n, Some(buf.clone())));
-                            }
-                            if ui_kit::button(ui, tr("ui.agent_chat_cancel"), ui_kit::Button::Normal).clicked() {
-                                edit_done = Some((n, None));
-                            }
-                        });
-                    }
-                    _ => {
-                        if !p.text.is_empty() {
-                            ui.add(egui::Label::new(RichText::new(&p.text).color(t.text)).selectable(true).wrap());
-                        }
-                        if p.image {
-                            ui.label(RichText::new(tr("ui.agent_chat_view_attached")).color(t.text_dim).size(crate::theme::Tokens::get().font_small));
-                        }
-                        context_chips(ui, &p.context, false);
-                        files_line(ui, p.files.iter().map(|f| f.name.as_str()));
-                    }
                 }
-            });
+                _ => {
+                    if !p.text.is_empty() {
+                        ui.add(egui::Label::new(RichText::new(&p.text).color(t.text)).selectable(true).wrap());
+                    }
+                    if p.image {
+                        ui.label(RichText::new(tr("ui.agent_chat_view_attached")).color(t.text_dim).size(crate::theme::Tokens::get().font_small));
+                    }
+                    context_chips(ui, &p.context, false);
+                    files_line(ui, p.files.iter().map(|f| f.name.as_str()));
+                }
+            }
+        });
     }
     if !app.agent_chat.pending.is_empty() && editing.is_none() {
         ui.horizontal(|ui| {
             if busy {
-                let b = ui_kit::button(ui, tr("ui.agent_chat_send_now"), ui_kit::Button::Normal).on_hover_text(tr("ui.agent_chat_send_now_tip"));
+                let b =
+                    ui_kit::button(ui, tr("ui.agent_chat_send_now"), ui_kit::Button::Normal).backing_on_hover_text(tr("ui.agent_chat_send_now_tip"));
                 crate::scenario::publish_handle("agent_chat:send_now", b.rect.center());
                 send_now_clicked = b.clicked();
             } else {
@@ -2054,34 +2058,38 @@ pub(super) fn remove_tip(f: &attach::Attachment) -> &'static str {
 fn loading_chip(ui: &mut egui::Ui, name: &str, importing: bool, i: usize, w: f32) -> bool {
     let t = Tokens::get();
     let mut clicked = false;
-    let r = egui::Frame::NONE
-        .fill(t.toolbar)
-        .stroke(t.control_border_stroke(t.border))
-        .corner_radius(t.control_radius)
-        .inner_margin(egui::Margin::symmetric(4, 3))
-        .show(ui, |ui| {
+    let r = crate::ui_kit::Container::show_backing(
+        ui,
+        egui::Frame::NONE
+            .fill(t.toolbar)
+            .stroke(t.control_border_stroke(t.border))
+            .corner_radius(t.control_radius)
+            .inner_margin(egui::Margin::symmetric(4, 3)),
+        |ui| {
             let inner = (w - 10.0).max(40.0);
             ui.set_width(inner);
             ui.horizontal(|ui| {
                 ui.spacing_mut().item_spacing.x = 4.0;
                 let doing = tr(if importing { "ui.agent_chat_file_importing" } else { "ui.agent_chat_file_loading" });
-                let mark = ui.add(egui::Spinner::new().size(t.form_icon_size)).on_hover_text(doing).rect.width();
+                let mark = ui.add(egui::Spinner::new().size(t.form_icon_size)).backing_on_hover_text(doing).rect.width();
                 let name_w = (inner - mark - 18.0 - 8.0).max(8.0);
                 ui.allocate_ui(vec2(name_w, 20.0), |ui| {
                     ui.set_width(name_w);
                     ui.add(egui::Label::new(RichText::new(name).size(t.font_small).color(t.text_dim)).truncate())
                 })
                 .inner
-                .on_hover_text(name);
+                .backing_on_hover_text(name);
                 let (r, x) = ui.allocate_exact_size(vec2(18.0, 18.0), Sense::click());
                 let c = r.center();
                 let s = Stroke::new(1.3, if x.hovered() { t.text } else { t.text_dim });
                 ui.painter().line_segment([c + vec2(-3.5, -3.5), c + vec2(3.5, 3.5)], s);
                 ui.painter().line_segment([c + vec2(-3.5, 3.5), c + vec2(3.5, -3.5)], s);
                 crate::scenario::publish_handle(&format!("agent_chat:file_loading_remove:{i}"), c);
-                clicked = x.on_hover_text(tr(if importing { "ui.agent_chat_remove_imported" } else { "ui.agent_chat_remove_file" })).clicked();
+                clicked =
+                    x.backing_on_hover_text(tr(if importing { "ui.agent_chat_remove_imported" } else { "ui.agent_chat_remove_file" })).clicked();
             });
-        });
+        },
+    );
     crate::scenario::publish_handle(&format!("agent_chat:file_loading:{i}"), r.response.rect.center());
     clicked
 }
@@ -2091,12 +2099,14 @@ fn loading_chip(ui: &mut egui::Ui, name: &str, importing: bool, i: usize, w: f32
 fn chip(ui: &mut egui::Ui, thumbs: &mut std::collections::HashMap<u64, egui::TextureHandle>, f: &attach::Attachment, i: usize, w: f32) -> bool {
     let t = Tokens::get();
     let mut clicked = false;
-    let r = egui::Frame::NONE
-        .fill(t.toolbar)
-        .stroke(t.control_border_stroke(t.border))
-        .corner_radius(t.control_radius)
-        .inner_margin(egui::Margin::symmetric(4, 3))
-        .show(ui, |ui| {
+    let r = crate::ui_kit::Container::show_backing(
+        ui,
+        egui::Frame::NONE
+            .fill(t.toolbar)
+            .stroke(t.control_border_stroke(t.border))
+            .corner_radius(t.control_radius)
+            .inner_margin(egui::Margin::symmetric(4, 3)),
+        |ui| {
             let inner = (w - 10.0).max(40.0);
             ui.set_width(inner);
             ui.horizontal(|ui| {
@@ -2130,16 +2140,17 @@ fn chip(ui: &mut egui::Ui, thumbs: &mut std::collections::HashMap<u64, egui::Tex
                     ui.add(egui::Label::new(RichText::new(&f.name).size(t.font_small)).truncate())
                 })
                 .inner
-                .on_hover_text(&f.name);
+                .backing_on_hover_text(&f.name);
                 let (r, x) = ui.allocate_exact_size(vec2(18.0, 18.0), Sense::click());
                 let c = r.center();
                 let s = Stroke::new(1.3, if x.hovered() { t.text } else { t.text_dim });
                 ui.painter().line_segment([c + vec2(-3.5, -3.5), c + vec2(3.5, 3.5)], s);
                 ui.painter().line_segment([c + vec2(-3.5, 3.5), c + vec2(3.5, -3.5)], s);
                 crate::scenario::publish_handle(&format!("agent_chat:file_remove:{i}"), c);
-                clicked = x.on_hover_text(remove_tip(f)).clicked();
+                clicked = x.backing_on_hover_text(remove_tip(f)).clicked();
             });
-        });
+        },
+    );
     crate::scenario::publish_target(&format!("agent_chat:file:{i}"), r.response.rect);
     clicked
 }
@@ -2164,7 +2175,7 @@ fn add_menu(app: &mut SolveApp, ui: &mut egui::Ui) {
         }
     });
     crate::scenario::publish_handle("agent_chat:add", r.response.rect.center());
-    r.response.on_hover_text(tr("ui.agent_chat_add"));
+    r.response.backing_on_hover_text(tr("ui.agent_chat_add"));
     if choose {
         app.pick_file(tr("ui.agent_chat_attachable"), &attach::extensions(), |app, path| {
             if let Some(path) = path
@@ -2232,7 +2243,7 @@ fn tool_card(ui: &mut egui::Ui, n: usize, call: &ToolCall) {
                         Some(words) => RichText::new(words).size(t.font_caption).color(t.text),
                         None => RichText::new(summary::plain_title(call.title)).monospace().size(t.font_caption).color(t.text),
                     };
-                    ui.add(egui::Label::new(text).truncate().selectable(false)).on_hover_text(call.title);
+                    ui.add(egui::Label::new(text).truncate().selectable(false)).backing_on_hover_text(call.title);
                 });
             });
         });
@@ -2242,7 +2253,7 @@ fn tool_card(ui: &mut egui::Ui, n: usize, call: &ToolCall) {
             state_.toggle(ui);
         }
         if details {
-            click.on_hover_text(tr("ui.ai_tool_unfold"));
+            click.backing_on_hover_text(tr("ui.ai_tool_unfold"));
         }
         state_.show_body_unindented(ui, |ui| {
             ui.indent(id.with("detail"), |ui| {

crates/ui-egui/src/agent_chat/settings.rs

@@ -7,6 +7,7 @@ use super::agents::{self, AgentConfig, Kind, Mode, Protocol};
 use super::backend::TestError;
 use super::*;
 use crate::ui_kit;
+use crate::ui_kit::BackingTooltipExt as _;
 
 #[derive(Clone, Copy, Debug, Default, PartialEq, Eq)]
 pub enum AddKind {
@@ -405,7 +406,7 @@ fn start_test(app: &SolveApp, e: &agents::Entry, key: Option<String>) -> Test {
 /// An endpoint's request timeout field: seconds, 30 s to an hour.
 fn timeout_field(ui: &mut egui::Ui, secs: &mut u64, handle: &str) -> bool {
     let r = ui_kit::number_field(ui, secs, agents::MIN_REQUEST_TIMEOUT_S..=agents::MAX_REQUEST_TIMEOUT_S, 5.0, "")
-        .on_hover_text(tr("ui.ai_request_timeout_hint"));
+        .backing_on_hover_text(tr("ui.ai_request_timeout_hint"));
     r.widget_info(|| {
         let mut info = egui::WidgetInfo::drag_value(ui.is_enabled(), *secs as f64);
         info.label = Some(tr("prefs.assistant_seconds_aria").to_owned());
@@ -419,7 +420,7 @@ fn timeout_field(ui: &mut egui::Ui, secs: &mut u64, handle: &str) -> bool {
 /// The free-text reasoning effort field with its hover hint; true when the text changed.
 fn effort_field(ui: &mut egui::Ui, effort: &mut String, handle: &str) -> bool {
     let response = ui_kit::cell_editor(ui, ui.id().with("ai_reasoning_effort"), effort, tr("ui.ai_reasoning_effort_field_hint"), false)
-        .on_hover_text(tr("ui.ai_reasoning_effort_hint"));
+        .backing_on_hover_text(tr("ui.ai_reasoning_effort_hint"));
     crate::scenario::publish_target(handle, response.rect);
     response.changed()
 }
@@ -446,14 +447,14 @@ pub fn page(app: &mut SolveApp, ui: &mut egui::Ui) {
         ui_kit::settings_heading(ui, tr("prefs.assistant"), tr("ai.prefs.intro"));
         ui_kit::settings_section(ui, "assistant_availability", tr("ai.prefs.availability"), |ui| {
             ui.horizontal(|ui| {
-                let response =
-                    ui_kit::checkbox(ui, tr("ui.ai_show_features"), &mut app.preferences.ai_features).on_hover_text(tr("ui.ai_show_features_note"));
+                let response = ui_kit::checkbox(ui, tr("ui.ai_show_features"), &mut app.preferences.ai_features)
+                    .backing_on_hover_text(tr("ui.ai_show_features_note"));
                 crate::scenario::publish_handle("prefs:ai_features", response.rect.center());
                 ui_kit::help_icon(ui, tr("ui.ai_show_features_note"));
             });
             ui.add_enabled_ui(app.preferences.ai_features && !cfg!(target_arch = "wasm32"), |ui| {
                 let response = ui_kit::checkbox(ui, tr("ui.ai_toolbar_button"), &mut app.preferences.ai_toolbar_button)
-                    .on_hover_text(tr("ui.ai_toolbar_button_note"));
+                    .backing_on_hover_text(tr("ui.ai_toolbar_button_note"));
                 crate::scenario::publish_handle("prefs:ai_toolbar_button", response.rect.center());
             });
             if cfg!(target_arch = "wasm32") {
@@ -487,7 +488,7 @@ fn connecting_section(app: &mut SolveApp, ui: &mut egui::Ui) {
             ("ai.prefs.open_at_start", "ai.prefs.open_at_start_note", "agent_chat_open_at_start", &mut app.preferences.agent_chat_open_at_start),
         ] {
             ui.horizontal(|ui| {
-                let response = ui_kit::checkbox(ui, tr(label), value).on_hover_text(tr(help));
+                let response = ui_kit::checkbox(ui, tr(label), value).backing_on_hover_text(tr(help));
                 crate::scenario::publish_handle(&format!("prefs:{handle}"), response.rect.center());
                 ui_kit::help_icon(ui, tr(help));
             });
@@ -540,7 +541,8 @@ fn permissions_section(app: &mut SolveApp, ui: &mut egui::Ui) {
             .collect();
         ui_kit::section_count(ui, "always_allowed", tr("ui.ai_always_allowed"), false, Some(remembered.len()), |ui| {
             if remembered.is_empty() {
-                ui_kit::text(ui, tr("ai.prefs.no_saved_approvals"), ui_kit::Text::Hint("none")).on_hover_text(tr("ui.ai_always_allowed_none"));
+                ui_kit::text(ui, tr("ai.prefs.no_saved_approvals"), ui_kit::Text::Hint("none"))
+                    .backing_on_hover_text(tr("ui.ai_always_allowed_none"));
             }
             let names: std::collections::HashMap<_, _> = agents::entries(app).into_iter().map(|entry| (entry.id, entry.name)).collect();
             for (agent, tools) in remembered {
@@ -605,7 +607,7 @@ fn panel_section(app: &mut SolveApp, ui: &mut egui::Ui) {
                 }
                 if limit != 0 {
                     let response =
-                        ui_kit::settings_number(ui, &mut p.agent_chat_turn_limit, 1..=200, 1.0).on_hover_text(tr("ai.prefs.turn_limit_hint"));
+                        ui_kit::settings_number(ui, &mut p.agent_chat_turn_limit, 1..=200, 1.0).backing_on_hover_text(tr("ai.prefs.turn_limit_hint"));
                     response.widget_info(|| {
                         let mut info = egui::WidgetInfo::drag_value(ui.is_enabled(), f64::from(p.agent_chat_turn_limit));
                         info.label = Some(tr("prefs.assistant_limit").to_owned());
@@ -625,7 +627,7 @@ fn pointer_section(app: &mut SolveApp, ui: &mut egui::Ui) {
             ui,
             |ui| {
                 let response = ui_kit::checkbox(ui, tr("ai.prefs.show_pointer"), &mut app.ui.agent_cursor.show)
-                    .on_hover_text(crate::i18n::tr_label("Show the pointer an AI agent moves (#35)"));
+                    .backing_on_hover_text(crate::i18n::tr_label("Show the pointer an AI agent moves (#35)"));
                 crate::scenario::publish_target("prefs:agent_pointer_show", response.rect);
                 ui.add_enabled_ui(app.ui.agent_cursor.show, |ui| {
                     let speed_label_width = ui_kit::ContentWidth::label(ui, tr("ai.prefs.pointer_speed")) + crate::theme::Tokens::get().space_4;
@@ -653,7 +655,7 @@ fn pointer_section(app: &mut SolveApp, ui: &mut egui::Ui) {
                     });
                     ui.horizontal(|ui| {
                         let response = ui_kit::checkbox(ui, tr("ai.prefs.follow_camera"), &mut app.ui.agent_cursor.follow_camera)
-                            .on_hover_text(tr("prefs.assistant_follow_help"));
+                            .backing_on_hover_text(tr("prefs.assistant_follow_help"));
                         crate::scenario::publish_target("prefs:agent_pointer_follow", response.rect);
                         ui_kit::help_icon(ui, tr("prefs.assistant_follow_help"));
                     });
@@ -719,13 +721,13 @@ fn agents_section(app: &mut SolveApp, ui: &mut egui::Ui) {
                                         Kind::Api => "ui.ai_test_api_tip",
                                         Kind::Anthropic => "ui.ai_test_anthropic_tip",
                                     };
-                                    if test_button.on_hover_text(tr(tip)).clicked() {
+                                    if test_button.backing_on_hover_text(tr(tip)).clicked() {
                                         test = Some(entry.clone());
                                     }
                                     if !entry.found {
                                         let edit_button = ui_kit::button(ui, tr("ui.ai_edit"), ui_kit::Button::Small);
                                         crate::scenario::publish_handle(&format!("prefs:ai_edit:{}", entry.id), edit_button.rect.center());
-                                        if edit_button.on_hover_text(tr("ui.ai_edit_tip")).clicked() {
+                                        if edit_button.backing_on_hover_text(tr("ui.ai_edit_tip")).clicked() {
                                             edit = Some(entry.id.clone());
                                         }
                                     }
@@ -748,7 +750,7 @@ fn agents_section(app: &mut SolveApp, ui: &mut egui::Ui) {
                                     }
                                 },
                             );
-                            ui_kit::settings_short_note(ui, &detail).on_hover_text(&entry.id);
+                            ui_kit::settings_short_note(ui, &detail).backing_on_hover_text(&entry.id);
                             // Wide enough for an endpoint's "Request timeout" or "Reasoning effort" too,
                             // so all rows line up.
                             let label_w = [tr("ui.ai_permissions"), tr("ui.ai_request_timeout"), tr("ui.ai_reasoning_effort")]
@@ -819,7 +821,7 @@ fn agents_section(app: &mut SolveApp, ui: &mut egui::Ui) {
                             }
                             if app.preferences.agent_permissions.get(&entry.id) == Some(&Mode::All) {
                                 ui_kit::text(ui, tr("ai.prefs.override_all_warning"), ui_kit::Text::Report("agent_permissions_warning", true))
-                                    .on_hover_text(tr("ui.ai_mode_all_warning"));
+                                    .backing_on_hover_text(tr("ui.ai_mode_all_warning"));
                             }
                             test_line(ui, &app.agent_chat.settings.tests.get(&entry.id));
                         });

crates/ui-egui/src/agent_cursor.rs

@@ -502,7 +502,8 @@ pub fn paint(app: &SolveApp, ctx: &egui::Context) {
             .interactable(false)
             .fade_in(false)
             .show(ctx, |ui| {
-                Container::popup_frame(ui.style()).fill(t.overlay).show(ui, |ui| {
+                let frame = Container::popup_frame(ui.style()).fill(t.overlay);
+                Container::show_backing(ui, frame, |ui| {
                     ui.label(egui::RichText::new(crate::i18n::tr_label(label)).size(t.font_label).color(t.text));
                 });
             });

crates/ui-egui/src/blur.rs

@@ -40,19 +40,24 @@ impl Counters {
 }
 
 pub fn validate_radius(radius: f32) -> Result<f32, &'static str> {
-    if radius.is_finite() && (0.0..=40.0).contains(&radius) {
+    if radius.is_finite() && (0.0..=60.0).contains(&radius) {
         Ok(radius)
     } else {
-        Err("blur radius must be finite and between 0 and 40 physical pixels")
+        Err("blur radius must be finite and between 0 and 60 physical pixels")
     }
 }
 
 /// Original Kawase schedule. Offsets are in input texels; the first level is half sized.
 pub fn schedule(radius: f32) -> Option<(usize, f32)> {
+    schedule_capped(radius, 5)
+}
+
+/// A transient quality cap changes pass count, retaining the requested physical radius.
+pub fn schedule_capped(radius: f32, cap: usize) -> Option<(usize, f32)> {
     if validate_radius(radius).ok()? == 0.0 {
         return None;
     }
-    let steps = if radius <= 8.0 {
+    let steps = (if radius <= 8.0 {
         2
     } else if radius <= 18.0 {
         3
@@ -60,13 +65,120 @@ pub fn schedule(radius: f32) -> Option<(usize, f32)> {
         4
     } else {
         5
-    };
+    })
+    .min(cap.clamp(2, 5));
     // Per-axis tap variance: down 1/2, up 4/3, scaled by input texel size.
     // Target tap sigma = radius / 2. Resampling adds its own measurable footprint.
     let variance = (35.0 / 18.0) * (4.0_f32.powi(steps as i32) - 1.0);
     Some((steps, radius / (2.0 * variance.sqrt())))
 }
 
+/// Evidence from the native pass owner's actual submission, never UI construction time.
+#[derive(Clone, Copy, Debug)]
+pub struct PaintedFrame {
+    pub frame: u64,
+    pub interval_ms: Option<f64>,
+    pub continuous: bool,
+}
+
+#[derive(Debug)]
+pub(crate) struct Guard {
+    pub cap: usize,
+    pub streak: u8,
+    pub notice: bool,
+    pub opted_out: bool,
+    original: Option<usize>,
+    announced: bool,
+}
+
+impl Default for Guard {
+    fn default() -> Self {
+        Self { cap: 5, streak: 0, notice: false, opted_out: false, original: None, announced: false }
+    }
+}
+
+impl Guard {
+    pub fn reset(&mut self) {
+        self.streak = 0;
+    }
+
+    pub fn observe(&mut self, radius: f32, interval_ms: f64, eligible: bool) {
+        let steps = schedule_capped(radius, self.cap).map_or(0, |s| s.0);
+        if self.opted_out || !eligible || !interval_ms.is_finite() || interval_ms <= 22.0 || steps <= 2 {
+            self.reset();
+            return;
+        }
+        self.streak = self.streak.saturating_add(1);
+        if self.streak == 60 {
+            self.original.get_or_insert(self.cap);
+            self.cap = steps - 1;
+            self.reset();
+            if !self.announced {
+                self.notice = true;
+                self.announced = true;
+            }
+        }
+    }
+
+    pub fn undo(&mut self) {
+        if let Some(original) = self.original.take() {
+            self.cap = original;
+        }
+        self.opted_out = true;
+        self.notice = false;
+        self.reset();
+    }
+}
+
+/// Session-only state. Harness inputs never replace a real GPU capability with success.
+#[derive(Default)]
+pub(crate) struct Session {
+    pub guard: Guard,
+    pub harness_radius: Option<f32>,
+    pub harness_unavailable: Option<&'static str>,
+    pub evidence_fixture: Option<&'static str>,
+    identity: Option<(u64, u32)>,
+    frame: Option<u64>,
+    painted: Option<u64>,
+    dismissed: std::collections::VecDeque<u64>,
+}
+
+impl Session {
+    pub fn sample(&mut self, ctx: &egui::Context, revision: u64, radius: f32, available: bool, paint: Option<PaintedFrame>) {
+        let frame = ctx.cumulative_frame_nr();
+        if self.frame == Some(frame) {
+            return;
+        } // egui layout re-passes do not count twice.
+        self.frame = Some(frame);
+        let identity = (revision, radius.to_bits());
+        if self.identity.as_ref() != Some(&identity) {
+            self.identity = Some(identity);
+            self.painted = paint.map(|p| p.frame);
+            self.guard.reset();
+            return;
+        }
+        let eligible = available
+            && radius > 0.0
+            && ctx.requested_repaint_last_pass()
+            && ctx.input(|i| i.viewport().visible() != Some(false))
+            && paint.is_some_and(|p| p.frame.checked_add(1) == Some(frame) && self.painted != Some(p.frame) && p.continuous);
+        self.painted = paint.map(|p| p.frame);
+        self.guard.observe(radius, paint.and_then(|p| p.interval_ms).unwrap_or(0.0), eligible);
+    }
+
+    pub fn dismissed(&self, key: u64) -> bool {
+        self.dismissed.contains(&key)
+    }
+    pub fn dismiss(&mut self, key: u64) {
+        if !self.dismissed(key) {
+            if self.dismissed.len() == 64 {
+                self.dismissed.pop_front();
+            }
+            self.dismissed.push_back(key);
+        }
+    }
+}
+
 #[cfg(not(target_arch = "wasm32"))]
 #[path = "blur_native.rs"]
 mod implementation;
@@ -100,6 +212,14 @@ mod implementation {
         }
         pub fn begin(&mut self, _: &egui::Context, _: bool) {}
         pub fn set_surface_alpha(&mut self, _: Option<u8>) {}
+        pub fn set_available(&mut self, _: bool) {}
+        pub fn set_tier_cap(&mut self, _: usize) {}
+        pub fn software_adapter(&self) -> bool {
+            false
+        }
+        pub fn painted_frame(&self) -> Option<PaintedFrame> {
+            None
+        }
     }
     pub fn enabled() -> bool {
         false

crates/ui-egui/src/blur.wgsl

@@ -1,4 +1,4 @@
-// Original SolidCraft viewport-only dual-Kawase and rounded panel composition.
+// Original SolidCraft backdrop dual-Kawase and rounded surface composition.
 struct Params { a: vec4<f32>, rect: vec4<f32>, corners: vec4<f32>, top: vec4<f32>, bottom: vec4<f32>, outside: vec4<f32> }
 @group(0) @binding(0) var image: texture_2d<f32>;
 @group(0) @binding(1) var filtering: sampler;
@@ -16,7 +16,7 @@ fn gamma(c: vec3<f32>) -> vec3<f32> {
 }
 fn load_linear(at: vec2<i32>) -> vec4<f32> {
     let c = textureLoad(image, clamp(at, vec2<i32>(0), vec2<i32>(textureDimensions(image)) - vec2<i32>(1)), 0);
-    // Only the source is gamma encoded on unorm targets. It is opaque, so decoding
+    // Only the scene/composition input is gamma encoded on unorm targets. Decoding
     // each texel BEFORE bilinear interpolation avoids filtering encoded colors.
     return vec4<f32>(linear(c.rgb), c.a);
 }
@@ -60,7 +60,7 @@ fn sample_at(uv: vec2<f32>) -> vec4<f32> {
     let alpha = clamp(0.5 - distance, 0.0, 1.0) * p.a.w;
     let c = textureSample(image, filtering, v.position.xy / vec2<f32>(textureDimensions(image)));
     // Match egui: coverage/opacity multiply gamma-premultiplied RGB BEFORE the
-    // framebuffer conversion. B itself remains linear, opaque viewport color.
+    // framebuffer conversion. The sampled backdrop remains linear color.
     let premultiplied_gamma = gamma(c.rgb) * alpha;
     let rgb = select(premultiplied_gamma, linear(premultiplied_gamma), p.a.z > 0.5);
     return vec4<f32>(rgb, alpha);

crates/ui-egui/src/blur_native.rs

@@ -11,8 +11,8 @@ const BUDGET: u64 = 256 * 1024 * 1024;
 const MAX_MARKERS: usize = 256;
 type Params = [f32; 24];
 
-fn capability(adapter: &wgpu::Adapter, format: wgpu::TextureFormat, split: bool, msaa: u32) -> Capability {
-    if solidcraft_gpu::select::tier_of(adapter.get_info().device_type) == solidcraft_gpu::select::Tier::Software {
+fn capability(adapter: &wgpu::Adapter, device_type: wgpu::DeviceType, format: wgpu::TextureFormat, split: bool, msaa: u32) -> Capability {
+    if device_type == wgpu::DeviceType::Cpu {
         return Capability::Unavailable("software adapter (gpu-software)");
     }
     rendering_capability(adapter, format, split, msaa)
@@ -38,6 +38,7 @@ fn rendering_capability(adapter: &wgpu::Adapter, format: wgpu::TextureFormat, sp
 #[derive(Clone)]
 struct Host {
     adapter: wgpu::Adapter,
+    device_type: wgpu::DeviceType,
     device: wgpu::Device,
     queue: wgpu::Queue,
     renderer: std::sync::Weak<egui::epaint::mutex::RwLock<egui_wgpu::Renderer>>,
@@ -49,12 +50,14 @@ struct Host {
 }
 impl Host {
     fn capability(&self) -> Capability {
-        *self.capability.get_or_init(|| capability(&self.adapter, self.format, self.split, self.msaa))
+        *self.capability.get_or_init(|| capability(&self.adapter, self.device_type, self.format, self.split, self.msaa))
     }
 }
 
 pub struct State {
     radius: f32,
+    available: bool,
+    tier_cap: usize,
     host: Option<Host>,
     active: Option<Arc<Shared>>,
     retired: Counters,
@@ -69,6 +72,8 @@ impl Default for State {
     fn default() -> Self {
         Self {
             radius: 0.0,
+            available: true,
+            tier_cap: 5,
             host: None,
             active: None,
             retired: Counters::default(),
@@ -87,6 +92,7 @@ impl State {
         self.failure = None;
         self.host = Some(Host {
             adapter: rs.adapter.clone(),
+            device_type: rs.adapter.get_info().device_type,
             device: rs.device.clone(),
             queue: rs.queue.clone(),
             renderer: Arc::downgrade(&rs.renderer),
@@ -124,6 +130,25 @@ impl State {
     pub fn radius(&self) -> f32 {
         self.radius
     }
+    pub fn software_adapter(&self) -> bool {
+        self.host.as_ref().is_some_and(|h| h.device_type == wgpu::DeviceType::Cpu)
+    }
+    pub fn set_available(&mut self, available: bool) {
+        self.available = available;
+        if !available {
+            self.retire();
+        }
+    }
+    pub fn set_tier_cap(&mut self, cap: usize) {
+        let cap = cap.clamp(2, 5);
+        if self.tier_cap != cap {
+            self.retire();
+            self.tier_cap = cap;
+        }
+    }
+    pub fn painted_frame(&self) -> Option<PaintedFrame> {
+        self.active.as_ref()?.inner.lock().ok()?.painted
+    }
     pub fn capability(&self) -> Capability {
         let base = self.base_capability();
         if base == Capability::Available && self.active.as_ref().is_some_and(|s| s.inner.lock().is_ok_and(|i| i.missing_source)) {
@@ -207,7 +232,7 @@ impl State {
                 self.last_size = Some(size_key);
             }
         }
-        if self.base_capability() != Capability::Available || !size.is_finite() || size.x <= 0.0 || size.y <= 0.0 {
+        if !self.available || self.base_capability() != Capability::Available || !size.is_finite() || size.x <= 0.0 || size.y <= 0.0 {
             self.retire();
             return Scope { previous, alpha };
         }
@@ -216,6 +241,7 @@ impl State {
             Arc::new(Shared {
                 host: host.clone(),
                 radius: self.radius,
+                tier_cap: self.tier_cap,
                 painting_owner: std::sync::atomic::AtomicBool::new(true),
                 inner: Mutex::new(Inner { counts: self.retired, ..Inner::default() }),
             })
@@ -225,6 +251,12 @@ impl State {
             inner.serial = inner.serial.wrapping_add(1);
             inner.source_seen = false;
             inner.source_count = 0;
+            if inner.frame != ctx.cumulative_frame_nr() {
+                inner.frame = ctx.cumulative_frame_nr();
+                inner.continuous = ctx.requested_repaint_last_pass();
+            }
+            inner.rendered = false;
+            inner.drawn_before = inner.counts.markers_drawn;
         }
         if let Some(renderer) = host.renderer.upgrade() {
             renderer.write().frame_compositor = Some(shared.clone());
@@ -253,8 +285,11 @@ pub(crate) fn fixture_state(
 ) -> State {
     State {
         radius: 0.0,
+        available: true,
+        tier_cap: 5,
         host: Some(Host {
             adapter: adapter.clone(),
+            device_type: adapter.get_info().device_type,
             device: device.clone(),
             queue: queue.clone(),
             renderer: Arc::downgrade(renderer),
@@ -317,11 +352,18 @@ pub fn panel_fill(fill: Color32) -> Color32 {
 struct Shared {
     host: Host,
     radius: f32,
+    tier_cap: usize,
     inner: Mutex<Inner>,
     painting_owner: std::sync::atomic::AtomicBool,
 }
 #[derive(Default)]
 struct Inner {
+    frame: u64,
+    continuous: bool,
+    rendered: bool,
+    drawn_before: u64,
+    painted: Option<PaintedFrame>,
+    submitted_at: Option<std::time::Instant>,
     gpu: Option<Gpu>,
     markers: Vec<Marker>,
     counts: Counters,
@@ -340,10 +382,14 @@ struct Marker {
     corners: egui::CornerRadius,
     opacity: f32,
     snap: bool,
+    // Identity only: the paint job owns this callback for the entire frame. Keeping
+    // its Arc here would create a Shared -> callback -> Shared ownership cycle.
+    callback_id: usize,
 }
 
 pub fn decorate(painter: &Painter, frame: Frame, content: Rect, ordinary: Shape) -> Shape {
-    if frame.fill.a() == 255 || frame.fill.a() == 0 || !painter.is_visible() {
+    let opacity = painter.opacity();
+    if frame.fill.a() == 0 || (frame.fill.a() == 255 && opacity >= 1.0) || !opacity.is_finite() || opacity <= 0.0 || !painter.is_visible() {
         return ordinary;
     }
     CURRENT.with(|c| {
@@ -356,7 +402,7 @@ pub fn decorate(painter: &Painter, frame: Frame, content: Rect, ordinary: Shape)
         if !rect.is_finite() || !rect.is_positive() {
             return ordinary;
         }
-        let index = if let Ok(mut inner) = shared.inner.lock() {
+        let callback = if let Ok(mut inner) = shared.inner.lock() {
             if inner.markers.len() >= MAX_MARKERS {
                 inner.failure = Some("blur panel limit exceeded");
                 inner.gpu = None;
@@ -364,18 +410,19 @@ pub fn decorate(painter: &Painter, frame: Frame, content: Rect, ordinary: Shape)
                 return ordinary;
             }
             let index = inner.markers.len();
+            let callback = egui_wgpu::Callback::new_paint_callback(rect, PanelMarker { shared: shared.clone(), index });
             inner.markers.push(Marker {
                 rect,
                 corners: frame.corner_radius,
-                opacity: painter.opacity(),
+                opacity,
                 snap: painter.ctx().tessellation_options(|o| o.round_rects_to_pixels),
+                callback_id: Arc::as_ptr(&callback.callback) as *const () as usize,
             });
             inner.counts.markers_emitted += 1;
-            index
+            callback
         } else {
             return ordinary;
         };
-        let callback = egui_wgpu::Callback::new_paint_callback(rect, PanelMarker { shared: shared.clone(), index });
         Shape::Vec(vec![Shape::Callback(callback), ordinary])
     })
 }
@@ -477,7 +524,7 @@ impl CallbackTrait for Source {
             return Vec::new();
         }
         inner.source_seen = true;
-        let Some((steps, offset)) = schedule(self.shared.radius) else { return Vec::new() };
+        let Some((steps, offset)) = schedule_capped(self.shared.radius, self.shared.tier_cap) else { return Vec::new() };
         let Some(bytes) = target_bytes(screen.size_in_pixels, steps, self.shared.host.device.limits().max_texture_dimension_2d) else {
             inner.failure = Some("blur target is empty, exceeds device limits or memory budget");
             inner.gpu = None;
@@ -539,13 +586,9 @@ impl CallbackTrait for Source {
             }
         }
         counts.source_passes += 1;
-        for step in &gpu.chain {
-            let mut pass = pass(encoder, "blur_kawase", &step.target.view, wgpu::Color::TRANSPARENT);
-            pass.set_pipeline(if step.down { &gpu.down } else { &gpu.up });
-            pass.set_bind_group(0, &step.binding.group, &[]);
-            pass.draw(0..3, 0..1);
-            counts.blur_passes += 1;
-        }
+        // The backdrop pyramid is built at paint-order boundaries in render(),
+        // after the underlying UI has actually been drawn, rather than from this
+        // scene-only texture during preparation.
         gpu.pending = Some(key);
         Vec::new()
     }
@@ -575,6 +618,7 @@ impl Source {
         screen.size_in_pixels.hash(&mut h);
         screen.pixels_per_point.to_bits().hash(&mut h);
         self.shared.radius.to_bits().hash(&mut h);
+        self.shared.tier_cap.hash(&mut h);
         self.shared.host.format.hash(&mut h);
         h.finish()
     }
@@ -672,7 +716,7 @@ impl FrameCompositor for Shared {
         if !self.painting_owner.load(std::sync::atomic::Ordering::Relaxed) {
             return false;
         }
-        let (composition, pipeline, binding) = {
+        let (composition, pipeline, binding, marker_ids) = {
             let Ok(mut inner) = self.inner.lock() else { return false };
             if !inner.source_seen {
                 inner.missing_source = true;
@@ -688,14 +732,51 @@ impl FrameCompositor for Shared {
             if gpu.ready_serial != inner.serial || gpu.size != screen.size_in_pixels {
                 return false;
             }
-            let data = (gpu.composition.view.clone(), gpu.present.clone(), gpu.presentation.group.clone());
+            let mut marker_ids: Vec<_> = inner.markers.iter().map(|marker| marker.callback_id).collect();
+            marker_ids.sort_unstable();
+            let data = (gpu.composition.view.clone(), gpu.present.clone(), gpu.presentation.group.clone(), marker_ids);
             inner.counts.composition_passes += 1;
             data
         };
         {
             let color = wgpu::Color { r: clear[0] as f64, g: clear[1] as f64, b: clear[2] as f64, a: clear[3] as f64 };
-            let mut ui = pass(encoder, "blur_ui_composition", &composition, color);
-            renderer.render(&mut ui, jobs, screen);
+            let _clear = pass(encoder, "blur_ui_composition", &composition, color);
+        }
+        let mut start = 0;
+        let mut mesh_offset = 0;
+        let mut segment_passes = 0;
+        for end in 0..=jobs.len() {
+            let callback_id = jobs.get(end).and_then(|job| {
+                let egui::epaint::Primitive::Callback(callback) = &job.primitive else { return None };
+                Some(Arc::as_ptr(&callback.callback) as *const () as usize)
+            });
+            let marker = callback_id.is_some_and(|identity| marker_ids.binary_search(&identity).is_ok());
+            if !marker && end != jobs.len() {
+                continue;
+            }
+            if start < end {
+                let mut ui = load_pass(encoder, "blur_ui_segment", &composition);
+                renderer.render_with_mesh_offset(&mut ui, &jobs[start..end], screen, mesh_offset);
+                mesh_offset += jobs[start..end].iter().filter(|job| matches!(&job.primitive, egui::epaint::Primitive::Mesh(_))).count();
+                segment_passes += 1;
+            }
+            if marker {
+                // The preceding segment is complete before sampling its color target.
+                // Reuse the pyramid, but include previously painted UI in the backdrop.
+                if let Ok(mut inner) = self.inner.lock() {
+                    let Inner { gpu, counts, .. } = &mut *inner;
+                    if let Some(gpu) = gpu {
+                        for step in &gpu.chain {
+                            let mut blur = pass(encoder, "blur_backdrop", &step.target.view, wgpu::Color::TRANSPARENT);
+                            blur.set_pipeline(if step.down { &gpu.down } else { &gpu.up });
+                            blur.set_bind_group(0, &step.binding.group, &[]);
+                            blur.draw(0..3, 0..1);
+                            counts.blur_passes += 1;
+                        }
+                    }
+                }
+            }
+            start = end;
         }
         {
             let mut present = pass(encoder, "blur_present", target, wgpu::Color::TRANSPARENT);
@@ -704,7 +785,9 @@ impl FrameCompositor for Shared {
             present.draw(0..3, 0..1);
         }
         if let Ok(mut inner) = self.inner.lock() {
+            inner.counts.composition_passes += segment_passes;
             inner.counts.present_passes += 1;
+            inner.rendered = true;
         }
         true
     }
@@ -713,6 +796,19 @@ impl FrameCompositor for Shared {
             return;
         }
         if let Ok(mut inner) = self.inner.lock() {
+            if inner.rendered && inner.counts.markers_drawn > inner.drawn_before && !self.host.lost.is_lost() {
+                let now = std::time::Instant::now();
+                inner.painted = Some(PaintedFrame {
+                    frame: inner.frame,
+                    interval_ms: inner.submitted_at.map(|at| now.duration_since(at).as_secs_f64() * 1000.0),
+                    continuous: inner.continuous,
+                });
+                inner.submitted_at = Some(now);
+                inner.rendered = false;
+            } else {
+                inner.painted = None;
+                inner.submitted_at = None;
+            }
             if self.host.lost.is_lost() {
                 inner.gpu = None;
                 inner.counts.clear_live();
@@ -811,6 +907,19 @@ fn background_params(rect: Rect, clip: Rect, colors: [Color32; 2], outside: Colo
 }
 
 fn pass(encoder: &mut wgpu::CommandEncoder, label: &'static str, view: &wgpu::TextureView, clear: wgpu::Color) -> wgpu::RenderPass<'static> {
+    attachment_pass(encoder, label, view, wgpu::LoadOp::Clear(clear))
+}
+
+fn load_pass(encoder: &mut wgpu::CommandEncoder, label: &'static str, view: &wgpu::TextureView) -> wgpu::RenderPass<'static> {
+    attachment_pass(encoder, label, view, wgpu::LoadOp::Load)
+}
+
+fn attachment_pass(
+    encoder: &mut wgpu::CommandEncoder,
+    label: &'static str,
+    view: &wgpu::TextureView,
+    load: wgpu::LoadOp<wgpu::Color>,
+) -> wgpu::RenderPass<'static> {
     encoder
         .begin_render_pass(&wgpu::RenderPassDescriptor {
             label: Some(label),
@@ -818,7 +927,7 @@ fn pass(encoder: &mut wgpu::CommandEncoder, label: &'static str, view: &wgpu::Te
                 view,
                 resolve_target: None,
                 depth_slice: None,
-                ops: wgpu::Operations { load: wgpu::LoadOp::Clear(clear), store: wgpu::StoreOp::Store },
+                ops: wgpu::Operations { load, store: wgpu::StoreOp::Store },
             })],
             depth_stencil_attachment: None,
             timestamp_writes: None,
@@ -931,7 +1040,7 @@ impl Gpu {
             dimensions.push(last.map(|d| d.div_ceil(2)));
         }
         for (index, dims) in dimensions.iter().skip(1).enumerate() {
-            let input = chain.last().map_or(&source.view, |s| &s.target.view);
+            let input = chain.last().map_or(&composition.view, |s| &s.target.view);
             let mut p = [0.0; 24];
             p[0] = offset;
             p[1] = u8::from(index == 0 && !format.is_srgb()) as f32;
@@ -940,7 +1049,7 @@ impl Gpu {
             chain.push(Step { target, binding, down: true });
         }
         for dims in dimensions.iter().take(steps).rev() {
-            let input = chain.last().map_or(&source.view, |s| &s.target.view);
+            let input = chain.last().map_or(&composition.view, |s| &s.target.view);
             let mut p = [0.0; 24];
             p[0] = offset;
             let binding = Binding::new(device, &layout, &sampler, input, p, counts);

crates/ui-egui/src/browser.rs

@@ -6,6 +6,7 @@
 //! viewport, a double-click on a sketch edits it, and a right-click opens the item's menu
 //! ([`crate::context_menu`]).
 
+use crate::ui_kit::BackingTooltipExt as _;
 use crate::ui_kit::{Container, Surface};
 use solidcraft_engine::geom::prelude::*;
 
@@ -1201,7 +1202,7 @@ fn browser_collapsed_rail(app: &mut SolveApp, ui: &mut egui::Ui) {
     crate::scenario::publish_handle("left-browser-toggle", disclosure.center());
     crate::scenario::publish_target("browser:header", disclosure);
     response.widget_info(|| egui::WidgetInfo::labeled(egui::WidgetType::Button, ui.is_enabled(), crate::i18n::tr("ui.browser_title")));
-    if response.on_hover_text(crate::i18n::tr("ui.browser_expand")).clicked() {
+    if response.backing_on_hover_text(crate::i18n::tr("ui.browser_expand")).clicked() {
         app.preferences.timeline_left_browser_collapsed = false;
     }
     let galley = ui.painter().layout_no_wrap(crate::i18n::tr("ui.browser_title").to_owned(), crate::fonts::semibold(t.font_body), t.text);
@@ -1289,7 +1290,7 @@ fn browser_header(app: &mut SolveApp, ui: &mut egui::Ui, collapsible: bool) {
     ui.painter().galley(pos2(right - galley.size().x, rect.center().y - galley.size().y / 2.0), galley, t.text_dim);
     if collapsible {
         let tip = crate::i18n::tr(if collapsed { "ui.browser_expand" } else { "ui.browser_collapse" });
-        if response.on_hover_cursor(egui::CursorIcon::PointingHand).on_hover_text(tip).clicked() {
+        if response.on_hover_cursor(egui::CursorIcon::PointingHand).backing_on_hover_text(tip).clicked() {
             if stacked {
                 app.preferences.timeline_left_browser_collapsed = !app.preferences.timeline_left_browser_collapsed;
             } else if vertical {
@@ -1716,7 +1717,7 @@ fn occurrence_rows_inner(
     }
     if let Some(resp) = &r.resp {
         let inherited = if own_visible && !visible { "\nHidden by a parent placement. Show the parent to reveal this instance." } else { "" };
-        resp.clone().on_hover_ui(|ui| {
+        resp.clone().backing_on_hover_ui(|ui| {
             ui.label(&placement.tooltip);
             if !inherited.is_empty() {
                 ui.label(inherited.trim_start());

crates/ui-egui/src/browser/features.rs

@@ -351,7 +351,7 @@ fn marker_row(app: &SolveApp, ui: &mut egui::Ui, depth: usize) -> egui::Response
     if response.hovered() || response.dragged() {
         ui.ctx().set_cursor_icon(egui::CursorIcon::Grab);
     }
-    response.on_hover_text(crate::i18n::tr("ui.history_marker_tip"))
+    response.backing_on_hover_text(crate::i18n::tr("ui.history_marker_tip"))
 }
 
 /// Dragging the marker shows where it lands; letting go rolls the history there, through the

crates/ui-egui/src/canvas.rs

@@ -5,6 +5,7 @@
 //! command has its geometry, so typing a number sets the value at once; Enter applies, Tab
 //! moves on, Esc cancels.
 
+use crate::ui_kit::BackingTooltipExt as _;
 use crate::ui_kit::{Container, Surface};
 use egui::{Color32, Pos2, Stroke, vec2};
 use solidcore_record::{Vec2, Vec3};
@@ -927,7 +928,8 @@ fn value_box_full(
     // Background: under Preferences, Report a bug and other system windows (#9016). The box is
     // already kept clear of the command window (#6608), which floats at Middle with Features.
     Container::new(ui.ctx(), Surface::Canvas).area(area).fixed_pos(at).pivot(pivot).order(egui::Order::Background).show(ui.ctx(), |ui| {
-        Container::popup_frame(ui.style()).inner_margin(egui::Margin::symmetric(6, 3)).show(ui, |ui| {
+        let frame = Container::popup_frame(ui.style()).inner_margin(egui::Margin::symmetric(6, 3));
+        Container::show_backing(ui, frame, |ui| {
             ui.horizontal(|ui| {
                 ui.label(egui::RichText::new(crate::i18n::tr_label(label)).color(t.text_dim).size(crate::theme::Tokens::get().font_caption));
                 let r = crate::ui_kit::canvas_value_field(ui, id, value, keep_tab);
@@ -1801,7 +1803,8 @@ fn draw_revolve(
             .order(egui::Order::Background)
             .interactable(false);
         area.show(ui.ctx(), |ui| {
-            Container::popup_frame(ui.style()).inner_margin(egui::Margin::symmetric(6, 3)).show(ui, |ui| {
+            let frame = Container::popup_frame(ui.style()).inner_margin(egui::Margin::symmetric(6, 3));
+            Container::show_backing(ui, frame, |ui| {
                 let text = if extent.curved_to {
                     "To surface".into()
                 } else if extent.sweep.is_finite() {
@@ -1809,7 +1812,7 @@ fn draw_revolve(
                 } else {
                     "Choose target".into()
                 };
-                ui.label(text).on_hover_text(crate::i18n::tr_label("Determined by To Object. Choose Angle to edit the angular extent."));
+                ui.label(text).backing_on_hover_text(crate::i18n::tr_label("Determined by To Object. Choose Angle to edit the angular extent."));
             });
         });
     } else if let Kind::Revolve { angle, .. } = &mut d.kind {

crates/ui-egui/src/command_help.rs

@@ -5,6 +5,7 @@
 //! ships with its help: `every_toolbar_command_has_help` fails otherwise.
 
 use crate::i18n;
+use crate::ui_kit::BackingTooltipExt as _;
 
 /// The commands that have help text. Each one needs a `help.<id>` message in the catalogs.
 pub const DOCUMENTED: &[&str] = &[
@@ -335,7 +336,7 @@ pub fn help(command: &str) -> Option<String> {
 /// with the help of `command` below it when there is one.
 pub fn tooltip(response: egui::Response, command: &str, tip: String) -> egui::Response {
     let help = help(command);
-    response.on_hover_ui(move |ui| {
+    response.backing_on_hover_ui(move |ui| {
         ui.set_max_width(300.0);
         ui.label(tip);
         if let Some(help) = help {

crates/ui-egui/src/configuration_rules_ui.rs

@@ -1,6 +1,7 @@
 //! Structured configuration rule editing and non-mutating row preview.
 use crate::SolveApp;
 use crate::ui_kit;
+use crate::ui_kit::BackingTooltipExt as _;
 use egui::Ui;
 use serde_json::{Value, json};
 use solidcraft_engine::doc::config::{Column, ConfigRule, RuleCondition, RuleEffect, RuleOperator};
@@ -116,13 +117,13 @@ pub(super) fn show(ui: &mut Ui, app: &mut SolveApp, error: &mut Option<String>,
                 if ui_kit::button(ui, crate::i18n::tr_label("Edit"), ui_kit::Button::Normal).clicked() {
                     editor.rule = rule.clone();
                 }
-                let up = ui_kit::button(ui, "↑", ui_kit::Button::Enabled(index > 0)).on_hover_text(crate::i18n::tr_label("Move earlier"));
+                let up = ui_kit::button(ui, "↑", ui_kit::Button::Enabled(index > 0)).backing_on_hover_text(crate::i18n::tr_label("Move earlier"));
                 crate::scenario::publish_handle(&format!("config:rule:{}:up", rule.id), up.rect.center());
                 if up.clicked() {
                     *error = app.run("config.rule", json!({"id":rule.id,"index":index-1})).err();
                 }
                 if ui_kit::button(ui, "↓", ui_kit::Button::Enabled(index + 1 < rules.len()))
-                    .on_hover_text(crate::i18n::tr_label("Move later"))
+                    .backing_on_hover_text(crate::i18n::tr_label("Move later"))
                     .clicked()
                 {
                     *error = app.run("config.rule", json!({"id":rule.id,"index":index+1})).err();

crates/ui-egui/src/control.rs

@@ -653,8 +653,8 @@ fn dispatch(app: &mut SolveApp, ctx: &egui::Context, method: &str, p: &Value) ->
         "ui.blur" => {
             // Internal rendering harness; deliberately no saved preference or product UI.
             let radius = if let Some(radius) = p.get("radius_px") {
-                let Some(radius) = radius.as_f64().filter(|v| v.is_finite() && (0.0..=40.0).contains(v)) else {
-                    return err("radius_px must be finite and between 0 and 40");
+                let Some(radius) = radius.as_f64().filter(|v| v.is_finite() && (0.0..=60.0).contains(v)) else {
+                    return err("radius_px must be finite and between 0 and 60");
                 };
                 Some(radius as f32)
             } else {
@@ -673,18 +673,70 @@ fn dispatch(app: &mut SolveApp, ctx: &egui::Context, method: &str, p: &Value) ->
             } else {
                 None
             };
+            // Explicit, labelled evidence fixtures only. They can force a failure, never fake
+            // real renderer support. All validation precedes mutation, including old fields.
+            let fixture = if let Some(fixture) = p.get("fixture") {
+                let Some(fixture) =
+                    fixture.as_str().filter(|s| matches!(*s, "clear" | "gpu-software" | "reduce-transparency" | "web-unsupported" | "guard-60"))
+                else {
+                    return err("unknown blur evidence fixture");
+                };
+                Some(fixture)
+            } else {
+                None
+            };
             if let Some(radius) = radius {
                 if let Err(error) = app.blur.set_radius(radius) {
                     return err(error);
                 }
+                app.blur_session.harness_radius = Some(radius);
                 ctx.request_repaint();
             }
             if let Some(alpha) = alpha {
                 app.blur.set_surface_alpha(alpha);
                 ctx.request_repaint();
             }
+            if let Some(fixture) = fixture {
+                match fixture {
+                    "clear" => {
+                        app.blur_session.harness_unavailable = None;
+                        app.blur_session.harness_radius = None;
+                        app.blur_session.evidence_fixture = None;
+                    }
+                    "gpu-software" => {
+                        app.blur_session.harness_unavailable = Some("prefs.blur_software");
+                        app.blur_session.evidence_fixture = Some("gpu-software");
+                    }
+                    "reduce-transparency" => {
+                        app.blur_session.harness_unavailable = Some("prefs.blur_reduce_transparency");
+                        app.blur_session.evidence_fixture = Some("reduce-transparency");
+                    }
+                    "web-unsupported" => {
+                        app.blur_session.harness_unavailable = Some("prefs.blur_web");
+                        app.blur_session.evidence_fixture = Some("web-unsupported");
+                    }
+                    "guard-60" => {
+                        let radius = app.blur.radius();
+                        for _ in 0..60 {
+                            app.blur_session.guard.observe(radius, 23.0, true);
+                        }
+                        app.blur_session.evidence_fixture = Some("guard-60");
+                    }
+                    _ => {}
+                }
+                ctx.request_repaint();
+            }
+            let availability = crate::prefs::blur_availability(app);
+            let reason = match availability {
+                crate::theme_options::Availability::Unavailable(reason) => Some(app.tr(reason)),
+                crate::theme_options::Availability::Available => None,
+            };
             ok(
-                json!({"radius_px":app.blur.radius(), "max_radius_px":40, "capability":app.blur.capability_for(ctx.viewport_id()), "counters":app.blur.counters()}),
+                json!({"radius_px":app.blur.radius(), "max_radius_px":60, "capability":app.blur.capability_for(ctx.viewport_id()), "counters":app.blur.counters(),
+                    "available": availability == crate::theme_options::Availability::Available, "reason": reason,
+                    "evidence_fixture": app.blur_session.evidence_fixture,
+                    "guard": {"tier_cap": app.blur_session.guard.cap, "streak": app.blur_session.guard.streak,
+                        "notice": app.blur_session.guard.notice, "opted_out": app.blur_session.guard.opted_out}}),
             )
         }
         "ui.status_fixture" => wrap(crate::viewport_status_fixture::control(app, p)),
@@ -1694,7 +1746,7 @@ mod tests {
     #[test]
     fn blur_control_validates_before_mutation_and_reports_no_gpu() {
         let mut h = crate::scenario::Harness::new();
-        for invalid in [json!(-1), json!(41), json!("18"), json!(null)] {
+        for invalid in [json!(-1), json!(61), json!("18"), json!(null)] {
             let reply = h.call("ui.blur", json!({"radius_px":invalid}));
             assert_eq!(reply["ok"], false, "{reply}");
             assert_eq!(h.app.blur.radius(), 0.0);
@@ -1712,6 +1764,43 @@ mod tests {
         assert_eq!(h.app.blur.radius(), 0.0);
     }
 
+    #[test]
+    fn blur_evidence_fixtures_are_atomic_transient_and_never_fake_support() {
+        let mut h = crate::scenario::Harness::new();
+        let source: Value = serde_json::from_str(include_str!("../tests/fixtures/theme-blur.json")).unwrap();
+        assert_eq!(h.call("ui.prefs", json!({"theme_import":source,"theme_options":{"blur-review":{"blur":40}}}))["ok"], true);
+        h.frames(2);
+        let saved = h.app.preferences.theme_options.clone();
+        let revision = h.app.session.revision;
+        for invalid in [json!(null), json!([]), json!("available"), json!("unknown")] {
+            assert_eq!(h.call("ui.blur", json!({"fixture":invalid,"radius_px":8}))["ok"], false);
+            assert_eq!(h.app.blur.radius(), 40.0);
+            assert_eq!(h.app.blur_session.harness_radius, None);
+        }
+        for fixture in ["gpu-software", "reduce-transparency", "web-unsupported"] {
+            let reply = h.call("ui.blur", json!({"fixture":fixture}));
+            assert_eq!(reply["result"]["evidence_fixture"], fixture);
+            assert_eq!(reply["result"]["available"], false);
+            h.frames(2);
+            assert_eq!(h.app.blur.counters().textures_created, 0);
+            assert_eq!(h.app.blur.counters().markers_emitted, 0);
+            assert_eq!(h.app.preferences.theme_options, saved);
+        }
+        h.call("ui.blur", json!({"fixture":"clear"}));
+        h.call("ui.blur", json!({"fixture":"guard-60"}));
+        assert_eq!((h.app.blur_session.guard.cap, h.app.blur_session.guard.notice), (4, true));
+        assert_eq!(h.app.blur_session.evidence_fixture, Some("guard-60"));
+        h.app.blur_session.guard.undo();
+        assert_eq!((h.app.blur_session.guard.cap, h.app.blur_session.guard.opted_out), (5, true));
+        h.call("ui.blur", json!({"fixture":"guard-60"}));
+        assert_eq!(h.app.blur_session.guard.cap, 5);
+        assert_eq!(h.app.session.revision, revision, "quality actions never enter document undo");
+        assert_eq!(h.app.preferences.theme_options, saved);
+        h.call("ui.blur", json!({"fixture":"clear"}));
+        assert!(h.app.blur_session.evidence_fixture.is_none());
+        assert!(matches!(h.app.blur.capability(), crate::blur::Capability::Unavailable(_)), "clearing a fixture cannot manufacture a GPU");
+    }
+
     use serde_json::json;
     use solidcraft_engine::{Sel, Session};
 

crates/ui-egui/src/design_properties.rs

@@ -133,8 +133,20 @@ pub fn open_object(app: &mut SolveApp, command: &str, params: &Value, fallback:
     // copy beside it, the card shows when done. Headless and in tests (no wait set), here.
     // The worker reports how many bodies it has measured, and stops when the card closes (#8706).
     let progress = Arc::new(Progress::default());
+    // Tests hold the reply until let go (`apply_gate`), so a window thread held up under load
+    // cannot find the measurement already in where the card should still be measuring.
+    #[cfg(test)]
+    let gate = app.apply_gate.clone();
+    let hold = move || {
+        #[cfg(test)]
+        if let Some(gate) = gate
+            && let Ok(gate) = gate.lock()
+        {
+            let _ = gate.recv();
+        }
+    };
     if let Some(wait) = app.apply_off_thread
-        && let Some(rx) = measure_beside(app.session.scratch(), command, params, progress.clone())
+        && let Some(rx) = measure_beside(app.session.scratch(), command, params, progress.clone(), hold)
     {
         match rx.recv_timeout(wait) {
             Ok(reply) => opened(app, reply, fallback),
@@ -190,13 +202,14 @@ fn opened(app: &mut SolveApp, reply: Result<Value, String>, fallback: String) {
 }
 
 /// Run `command` on `copy` on a worker, watched by `progress`; the reply comes on the returned
-/// channel.
+/// channel once `hold` returns (which only tests make wait).
 #[cfg(not(target_arch = "wasm32"))]
 fn measure_beside(
     mut copy: solidcraft_engine::Session,
     command: &str,
     params: &Value,
     progress: Arc<Progress>,
+    hold: impl FnOnce() + Send + 'static,
 ) -> Option<std::sync::mpsc::Receiver<Result<Value, String>>> {
     let (tx, rx) = std::sync::mpsc::channel();
     let (command, params) = (command.to_string(), params.clone());
@@ -204,6 +217,7 @@ fn measure_beside(
         .name("properties".into())
         .spawn(move || {
             let reply = solidcraft_engine::doc::progress::watch(progress, || copy.execute(&command, &params));
+            hold();
             let _ = tx.send(reply.map_err(|e| e.to_string()));
         })
         .ok()?;
@@ -217,6 +231,7 @@ fn measure_beside(
     _command: &str,
     _params: &Value,
     _progress: Arc<Progress>,
+    _hold: impl FnOnce() + Send + 'static,
 ) -> Option<std::sync::mpsc::Receiver<Result<Value, String>>> {
     None
 }
@@ -631,9 +646,14 @@ mod tests {
         h.app.run("solid.box", json!({"length": 10, "width": 20, "height": 30, "body_name": "Block"})).unwrap();
         let here = h.app.session.execute("component.properties", &json!({})).unwrap();
         h.app.apply_off_thread = Some(std::time::Duration::ZERO);
+        // The worker holds its reply until let go, so a window thread held up under load cannot
+        // find it already in.
+        let (finish, gate) = std::sync::mpsc::channel();
+        h.app.apply_gate = Some(std::sync::Arc::new(std::sync::Mutex::new(gate)));
         super::open_object(&mut h.app, "component.properties", &json!({}), String::new());
         assert!(h.app.menu.props.is_none(), "nothing is waited for on the window thread");
         let m = h.app.menu.props_measuring.take().expect("measuring beside the window");
+        finish.send(()).unwrap();
         assert_eq!(m.rx.recv().unwrap().unwrap(), here, "the copy measures what the design here does");
 
         let (tx, rx) = std::sync::mpsc::channel();
@@ -674,11 +694,15 @@ mod tests {
             h.app.run("occurrence.copy", json!({"component": block, "translate": [20 * i, 0, 0]})).unwrap();
         }
         h.app.apply_off_thread = Some(std::time::Duration::ZERO);
+        // Held until checked: under load the worker could otherwise finish before the menu returns.
+        let (finish, gate) = std::sync::mpsc::channel();
+        h.app.apply_gate = Some(std::sync::Arc::new(std::sync::Mutex::new(gate)));
         let items = crate::context_menu::items(&h.app, &crate::context_menu::Target::Component { id: 0 });
         let item = items.iter().find(|i| i.label == "Properties").expect("Properties item");
         crate::context_menu::run_item(&mut h.app, item, egui::pos2(0.0, 0.0));
         assert!(h.app.menu.props_measuring.is_some(), "the menu returns at once, the card measuring");
         assert!(h.app.menu.props.is_none());
+        finish.send(()).unwrap();
         let deadline = std::time::Instant::now() + std::time::Duration::from_secs(300);
         while h.app.menu.props.is_none() {
             assert!(std::time::Instant::now() < deadline, "the measurements never came in");

crates/ui-egui/src/dialogs.rs

@@ -2,6 +2,7 @@
 //! inputs (geometry picked in the viewport, never typed), then runs its command; it never
 //! changes the design itself. Things selected before the command starts become its input.
 
+use crate::ui_kit::BackingTooltipExt as _;
 use crate::ui_kit::choice_row;
 use solidcraft_engine::geom::prelude::*;
 use std::hash::{Hash, Hasher};
@@ -526,6 +527,11 @@ pub struct Dialog {
     pub(crate) chain_applied: bool,
     /// A pattern's objects of the Object Type not shown now, restored when it is chosen again.
     pub(crate) other_objects: Vec<Sel>,
+    /// The multi-pick input whose picked items are listed under it, each removable (#3683).
+    pub(crate) listed: Option<usize>,
+    /// The listed item (and its input) whose row is under the pointer: the view lights it as a
+    /// hover (`viewport::list_hover`).
+    pub(crate) list_hover: Option<(usize, Sel)>,
     /// Shell feedback is derived from the picks, never saved as additional face references.
     shell_chain: std::cell::RefCell<Option<ShellChain>>,
     /// An extrude Press Pull opened with nothing selected: its first pick may be a curved face or
@@ -793,6 +799,8 @@ impl Dialog {
             picked_edges: Vec::new(),
             chain_applied,
             other_objects: Vec::new(),
+            listed: None,
+            list_hover: None,
             shell_chain: Default::default(),
             press_pull: false,
             op_auto: Default::default(),
@@ -1858,6 +1866,80 @@ impl Dialog {
         inp.items = items;
         self.error = None;
     }
+
+    /// What input `i`'s list of picked items shows, one row each (#3683): what its chip counts.
+    /// A rim or a surface split into pieces is one row, as it is one pick; a Shell with Tangent
+    /// Chain lists every face it opens.
+    pub(crate) fn listed_items(&self, s: &Session, i: usize) -> Vec<Sel> {
+        if i == 0
+            && let Some(faces) = self.shell_faces(s)
+        {
+            return faces;
+        }
+        let mut rows: Vec<Sel> = Vec::new();
+        let mut shown: Vec<Sel> = Vec::new();
+        for item in self.inputs.get(i).map(|inp| inp.items.as_slice()).unwrap_or_default() {
+            if shown.iter().any(|x| selection::same_item(x, item)) {
+                continue;
+            }
+            shown.extend(crate::viewport::grouped_selection(s, item));
+            rows.push(item.clone());
+        }
+        rows
+    }
+
+    /// Remove a listed row's item from input `i`, as picking it again toggles it off: the
+    /// pieces of its rim or surface go with it, and the hand-picked edges and the explicit
+    /// profile choice follow. A face a Shell's tangent chain opens goes with the picks whose
+    /// chain holds it.
+    pub(crate) fn remove_listed(&mut self, s: &Session, i: usize, item: &Sel) {
+        let shell_chain = i == 0 && self.shell_faces(s).is_some();
+        // A Fillet or Chamfer row its Tangent Chain brought goes with the picks whose chain holds
+        // it, as picking it again would; else ticking Tangent Chain again brings it back.
+        let fillet_chain = i == 0 && matches!(self.kind, Kind::Fillet { chain: true, .. }) && self.chain_applied;
+        let state = s.world_state().ok();
+        let mut gone = if shell_chain { Vec::new() } else { crate::viewport::grouped_selection(s, item) };
+        gone.push(item.clone());
+        if fillet_chain {
+            let seeds: Vec<Sel> = self
+                .picked_edges
+                .iter()
+                .filter(|seed| fillet_edges(s, seed, true).iter().any(|x| gone.iter().any(|g| selection::same_item(x, g))))
+                .cloned()
+                .collect();
+            for seed in &seeds {
+                gone.extend(fillet_edges(s, seed, true));
+            }
+            gone.extend(seeds);
+        }
+        let Some(inp) = self.inputs.get_mut(i) else { return };
+        match (shell_chain, item, state.as_ref()) {
+            (true, Sel::Face { body, index, .. }, Some(st)) => {
+                let model = st.body(body);
+                inp.items.retain(|pick| {
+                    let Sel::Face { body: b, point, .. } = pick else { return true };
+                    b != body || !model.is_some_and(|m| solidcraft_engine::doc::tangent_face_chain(m, &[*point]).iter().any(|(f, _)| f == index))
+                });
+            }
+            // Without the model to find the chain in, the row goes on its own.
+            _ => {
+                inp.items.retain(|x| !gone.iter().any(|g| selection::same_item(x, g)));
+                if i == 0 {
+                    self.picked_edges.retain(|x| !gone.iter().any(|g| selection::same_item(x, g)));
+                }
+            }
+        }
+        let empty = inp.items.is_empty();
+        if empty && self.listed == Some(i) {
+            self.listed = None;
+        }
+        if i == 0 && matches!(self.kind, Kind::Extrude { .. } | Kind::Revolve { .. } | Kind::Emboss { .. }) {
+            self.profile_selection_changed = true;
+        }
+        self.list_hover = None;
+        self.error = None;
+        self.sync_thread(s);
+    }
 }
 
 /// The edges a Fillet or Chamfer pick stands for: its tangent chain when `chain` is on, else
@@ -2593,7 +2675,7 @@ fn object_type_row(d: &mut Dialog, ui: &mut egui::Ui) {
     let cur = usize::from(inp.accept == selection::FEATURES);
     let mut ty = cur;
     // What the two kinds are, and that a sketch is neither (#10057).
-    choice_row(ui, "Object Type", "pat_obj", &mut ty, &["Bodies", "Features"]).on_hover_text(crate::i18n::tr("ui.pattern_object_type_tip"));
+    choice_row(ui, "Object Type", "pat_obj", &mut ty, &["Bodies", "Features"]).backing_on_hover_text(crate::i18n::tr("ui.pattern_object_type_tip"));
     if ty != cur {
         inp.accept = if ty == 1 { selection::FEATURES } else { BODIES };
         inp.label = objects_label(inp.accept);
@@ -2850,6 +2932,8 @@ pub(crate) fn input_rows_range(d: &mut Dialog, ui: &mut egui::Ui, s: &Session, n
     // Only one field may look active at a time (#10066): while a text editor holds the keyboard,
     // no pick field draws its accent ring, and clicking a pick field takes the keyboard back.
     let text_focus = crate::ui_kit::editor_has_focus(ui.ctx());
+    let mut toggle_list: Option<usize> = None;
+    let mut hovered: Option<(usize, Sel)> = None;
     let shell_count = d.shell_faces(s).map(|faces| faces.len());
     for (i, inp) in d.inputs.iter().enumerate().skip(range.start).take(range.end.saturating_sub(range.start)) {
         let stored_reference = stored_input_reference_key(d, i).and_then(|key| d.extra.get(key)).filter(|_| inp.items.is_empty());
@@ -2904,7 +2988,7 @@ pub(crate) fn input_rows_range(d: &mut Dialog, ui: &mut egui::Ui, s: &Session, n
                 } else {
                     format!("{} (click to pick into this input)", hint(inp))
                 };
-                if chip.on_hover_text(tooltip).clicked() {
+                if chip.backing_on_hover_text(tooltip).clicked() {
                     activate = Some(i);
                     surrender_keyboard_focus(ui);
                 }
@@ -2919,22 +3003,51 @@ pub(crate) fn input_rows_range(d: &mut Dialog, ui: &mut egui::Ui, s: &Session, n
                         clear = Some(i);
                         surrender_keyboard_focus(ui);
                     }
+                    // Several picks: an arrow beside the clear button lists them, each with its
+                    // own remove button (#3683). Drawn straight into the row, which is this field's
+                    // own: a scope around it would take room and widen the dialog.
+                    if inp.multi {
+                        let open = d.listed == Some(i);
+                        let at = rect.translate(vec2(-t.space_24, 0.0));
+                        let label = crate::i18n::tr_label(if open { "Hide the picked items" } else { "Show the picked items" });
+                        let arrow = crate::ui_kit::disclosure_button_at(ui, at, open, label);
+                        crate::scenario::publish_handle(&format!("dialog:list_toggle:{}", inp.label), arrow.rect.center());
+                        if arrow.clicked() {
+                            toggle_list = Some(i);
+                        }
+                    }
                 }
             });
         });
-        if matches!(d.kind, Kind::SketchModify(_)) && inp.multi {
-            for (index, item) in inp.items.iter().enumerate() {
-                if crate::ui_kit::list_row(ui, &format!("{}:{index}", inp.label), &selection_label(s, names, d, inp, item)).clicked() {
-                    remove = Some((i, index));
+        if inp.multi && d.listed == Some(i) && !inp.items.is_empty() {
+            let rows = d.listed_items(s, i);
+            egui::ScrollArea::vertical().id_salt(("picked_items", i)).max_height(t.control_height * 6.5).show(ui, |ui| {
+                for (index, item) in rows.into_iter().enumerate() {
+                    let row = crate::ui_kit::list_row(ui, &format!("{}:{index}", inp.label), &selection_label(s, names, d, inp, &item));
+                    if row.hovered() {
+                        hovered = Some((i, item.clone()));
+                    }
+                    if row.clicked() {
+                        remove = Some((i, item));
+                    }
                 }
-            }
+            });
         }
     }
-    if let Some((input, index)) = remove
-        && let Some(input) = d.inputs.get_mut(input)
-        && index < input.items.len()
-    {
-        input.items.remove(index);
+    // The row under the pointer lights its item in the view; rows of inputs drawn elsewhere
+    // keep theirs.
+    let ours = |h: &Option<(usize, Sel)>| h.as_ref().is_some_and(|(i, _)| range.contains(i));
+    if hovered.is_some() || ours(&d.list_hover) {
+        if d.list_hover != hovered {
+            ui.ctx().request_repaint();
+        }
+        d.list_hover = hovered;
+    }
+    if let Some(i) = toggle_list {
+        d.listed = if d.listed == Some(i) { None } else { Some(i) };
+    }
+    if let Some((input, item)) = remove {
+        d.remove_listed(s, input, &item);
     }
     if let Some(i) = activate {
         d.active = i;
@@ -2947,6 +3060,10 @@ pub(crate) fn input_rows_range(d: &mut Dialog, ui: &mut egui::Ui, s: &Session, n
         if let Some(key) = stored_input_reference_key(d, i) {
             d.extra.remove(key);
         }
+        if d.listed == Some(i) {
+            d.listed = None;
+            d.list_hover = None;
+        }
         let Some(inp) = d.inputs.get_mut(i) else { return };
         inp.items.clear();
         if i == 0 {
@@ -3071,7 +3188,7 @@ fn error_rows(app: &mut SolveApp, ctx: &egui::Context, d: &mut Dialog, ui: &mut
             ui.vertical(|ui| {
                 match &plain {
                     Some(FilletRefusal::Plain(plain)) => {
-                        crate::ui_kit::text(ui, plain, crate::ui_kit::Text::Report("error", true)).on_hover_text(shown_error(&error));
+                        crate::ui_kit::text(ui, plain, crate::ui_kit::Text::Report("error", true)).backing_on_hover_text(shown_error(&error));
                     }
                     Some(FilletRefusal::InField) => {}
                     None => {
@@ -3082,7 +3199,7 @@ fn error_rows(app: &mut SolveApp, ctx: &egui::Context, d: &mut Dialog, ui: &mut
                     if plain.is_some() {
                         let copy = crate::ui_kit::button(ui, tr("ui.copy_details"), crate::ui_kit::Button::Normal);
                         crate::scenario::publish_handle("dialog:copy_details", copy.rect.center());
-                        if copy.on_hover_text(tr("ui.copy_details_tip")).clicked() {
+                        if copy.backing_on_hover_text(tr("ui.copy_details_tip")).clicked() {
                             ui.ctx().copy_text(error.clone());
                         }
                     }
@@ -6199,6 +6316,11 @@ pub fn for_feature(app: &SolveApp, id: u64, marker: Option<usize>) -> Option<Dia
             {
                 d.extra.insert("corner".into(), json!("g2"));
             }
+            if let FeatureKind::Fillet { turn, .. } = &f.kind
+                && !turn.is_mitre()
+            {
+                d.extra.insert("turn".into(), json!("swept"));
+            }
             // A fillet that reduces or tapers a radius too large for its edges.
             if let FeatureKind::Fillet { fit, .. } = &f.kind {
                 use solidcraft_engine::doc::FilletFit;

crates/ui-egui/src/dialogs_all_tests.rs

@@ -1468,6 +1468,12 @@ fn dialog_profile_labels_name_the_sketch_in_coil_and_mirror() {
         h.app.start(command);
         h.app.dialog.as_mut().unwrap().preview_enabled = false;
         h.frames(3);
+        // A field that takes several picks lists them, labels and all, behind its arrow (#3683).
+        let (multi, label) = h.app.dialog.as_ref().map(|d| (d.inputs[0].multi, d.inputs[0].label)).unwrap();
+        if multi {
+            h.step(&json!({"click": {"handle": format!("dialog:list_toggle:{label}")}})).unwrap();
+            h.frames(2);
+        }
         let d = h.app.dialog.as_ref().unwrap();
         let input = &d.inputs[0];
         assert_eq!(input.items, vec![Sel::Profile { sketch, index: 0 }]);

crates/ui-egui/src/dialogs_appearance.rs

@@ -3,6 +3,7 @@
 //! body or face in the viewport, or onto a body's row in the Browser, applies at once; Apply
 //! (and OK) gives the picked objects the current look.
 
+use crate::ui_kit::BackingTooltipExt as _;
 use egui::Color32;
 use serde_json::{Value, json};
 use solidcraft_engine::Sel;
@@ -415,7 +416,7 @@ pub fn rows(app: &mut SolveApp, ui: &mut egui::Ui, k: &mut Ap, inputs: &mut [Sel
     });
     let mut enabled = k.pbr.is_some();
     let toggle = ui_kit::row(ui, app.tr("appearance.surface_response"), |ui| ui_kit::checkbox(ui, app.tr("appearance.pbr_opaque"), &mut enabled))
-        .on_hover_text(app.tr("appearance.pbr_help"));
+        .backing_on_hover_text(app.tr("appearance.pbr_help"));
     crate::scenario::publish_handle("appearance:pbr", toggle.rect.center());
     if toggle.changed() {
         detach_preset(k);
@@ -461,7 +462,7 @@ pub fn rows(app: &mut SolveApp, ui: &mut egui::Ui, k: &mut Ap, inputs: &mut [Sel
             });
         }
         if ui_kit::button(ui, "Remove override", ui_kit::Button::Enabled(has_target))
-            .on_hover_text(crate::i18n::tr_label("Restore the inherited component or physical material appearance"))
+            .backing_on_hover_text(crate::i18n::tr_label("Restore the inherited component or physical material appearance"))
             .clicked()
             && let Some(p) = clear_params(k, &picked)
         {
@@ -543,7 +544,7 @@ pub fn rows(app: &mut SolveApp, ui: &mut egui::Ui, k: &mut Ap, inputs: &mut [Sel
             }
         })
         .response
-        .on_hover_text(tip);
+        .backing_on_hover_text(tip);
     });
     // A swatch dropped on the model or the Browser.
     let released = ui.input(|i| i.pointer.any_released());

crates/ui-egui/src/dialogs_assembly.rs

@@ -6,6 +6,7 @@
 //! component shows where it goes, and with Animate the joint plays its motion.
 
 use crate::fonts::RichTextExt as _;
+use crate::ui_kit::BackingTooltipExt as _;
 use crate::ui_kit::{choice_row, expr_row, text_row};
 use egui::{Color32, Pos2, RichText, Stroke, vec2};
 use serde_json::{Value, json};
@@ -737,7 +738,7 @@ pub fn rows(app: &mut SolveApp, ui: &mut egui::Ui, k: &mut Asm, inputs: &mut [Se
                     crate::ui_kit::status_line(ui, &why, crate::ui_kit::StatusTone::Warning);
                     if !bodies.is_empty()
                         && crate::ui_kit::button(ui, crate::i18n::tr("cmd.component_from_bodies"), crate::ui_kit::Button::Normal)
-                            .on_hover_text(crate::i18n::tr("joint.from_bodies_hint"))
+                            .backing_on_hover_text(crate::i18n::tr("joint.from_bodies_hint"))
                             .clicked()
                     {
                         // A refusal shows on the status line; the picks stay either way.
@@ -773,7 +774,7 @@ pub fn rows(app: &mut SolveApp, ui: &mut egui::Ui, k: &mut Asm, inputs: &mut [Se
                 form_row(ui, "Animate", |ui| {
                     let label = crate::i18n::tr(if f.animate { "ui.joint_stop" } else { "ui.joint_play" });
                     if crate::ui_kit::button(ui, label, crate::ui_kit::Button::Normal)
-                        .on_hover_text(crate::i18n::tr_label("Play the joint's motion in the view"))
+                        .backing_on_hover_text(crate::i18n::tr_label("Play the joint's motion in the view"))
                         .clicked()
                     {
                         f.animate = !f.animate;
@@ -1034,7 +1035,7 @@ fn find_limits_row(app: &mut SolveApp, ui: &mut egui::Ui, f: &mut JointForm, id:
                 }
             });
         } else if crate::ui_kit::button(ui, crate::i18n::tr("joint.find_limits"), crate::ui_kit::Button::Normal)
-            .on_hover_text(crate::i18n::tr("joint.find_limits_hint"))
+            .backing_on_hover_text(crate::i18n::tr("joint.find_limits_hint"))
             .clicked()
         {
             find_limits(app, f, id, inputs);
@@ -1261,7 +1262,7 @@ fn interference_rows(app: &SolveApp, ui: &mut egui::Ui, r: &Value) {
     for u in unchecked {
         form_row(ui, &format!("{} · {}", u["a"].as_str().unwrap_or(""), u["b"].as_str().unwrap_or("")), |ui| {
             ui.label(RichText::new(crate::i18n::tr("dialog.could_not_be_checked")).color(t.warning))
-                .on_hover_text(u["reason"].as_str().unwrap_or(""));
+                .backing_on_hover_text(u["reason"].as_str().unwrap_or(""));
         });
     }
 }
@@ -1727,7 +1728,7 @@ pub(crate) fn timeline_joint_tiles(app: &mut SolveApp, ui: &mut egui::Ui, p: &eg
         if suppressed {
             p.line_segment([br.left_bottom() + vec2(4.0, -4.0), br.right_top() + vec2(-4.0, 4.0)], Stroke::new(1.5, t.text_dim));
         }
-        let resp = resp.on_hover_text(format!("{name}  ({kind:?} joint)\nDouble-click to edit · right-click for more"));
+        let resp = resp.backing_on_hover_text(format!("{name}  ({kind:?} joint)\nDouble-click to edit · right-click for more"));
         if resp.double_clicked() {
             open = edit_joint(app, id);
         } else if resp.clicked() {
@@ -1790,7 +1791,7 @@ pub(crate) fn timeline_joint_rows(app: &mut SolveApp, ui: &mut egui::Ui, ids: Op
             egui::FontId::proportional(crate::theme::Tokens::get().font_body),
             if suppressed { t.text_dim } else { t.text },
         );
-        let response = response.on_hover_text(format!("{name}  ({kind:?} joint)\nDouble-click to edit · right-click for more"));
+        let response = response.backing_on_hover_text(format!("{name}  ({kind:?} joint)\nDouble-click to edit · right-click for more"));
         if response.double_clicked() {
             open = edit_joint(app, id);
         } else if response.clicked() {
@@ -1862,7 +1863,7 @@ pub fn browser_joints(app: &mut SolveApp, ui: &mut egui::Ui, depth: usize) {
             },
         );
         if let Some(resp) = &r.resp {
-            resp.clone().on_hover_text(format!("{kind:?} joint"));
+            resp.clone().backing_on_hover_text(format!("{kind:?} joint"));
         }
         if r.eye {
             let _ = app.run("browser.visibility", json!({ "joints": [id], "visible": !visible }));
@@ -1951,7 +1952,7 @@ pub fn component_joints(app: &mut SolveApp, ui: &mut egui::Ui, path: &[u64], key
             },
         );
         if let Some(resp) = &r.resp {
-            resp.clone().on_hover_text(format!("{:?} joint", j.kind));
+            resp.clone().backing_on_hover_text(format!("{:?} joint", j.kind));
         }
         if r.eye {
             let _ = app.run("browser.visibility", json!({ "joints": [id], "visible": !visible }));

crates/ui-egui/src/dialogs_cam.rs

@@ -4,6 +4,7 @@
 //! where it touches) or a flat face. Picking the profile on a part chooses the joint that part
 //! turns on. Play turns the cam a full turn so the follower shows its motion before OK.
 
+use crate::ui_kit::BackingTooltipExt as _;
 use egui::RichText;
 use serde_json::{Value, json};
 use solidcraft_engine::Sel;
@@ -133,7 +134,7 @@ pub fn rows(app: &mut SolveApp, ui: &mut egui::Ui, f: &mut CamForm, inputs: &[Se
     form_row(ui, "Animate", |ui| {
         let label = crate::i18n::tr(if f.animate { "ui.joint_stop" } else { "ui.joint_play" });
         let r = crate::ui_kit::button(ui, label, crate::ui_kit::Button::Normal)
-            .on_hover_text(crate::i18n::tr_label("Play the joint's motion in the view"));
+            .backing_on_hover_text(crate::i18n::tr_label("Play the joint's motion in the view"));
         crate::scenario::publish_handle("dialog:Animate", r.rect.center());
         if r.clicked() {
             f.animate = !f.animate;

crates/ui-egui/src/dialogs_coupling.rs

@@ -4,6 +4,7 @@
 //! face also picks the joint it turns on. Play turns the driving joint so the coupling shows its
 //! motion before OK.
 
+use crate::ui_kit::BackingTooltipExt as _;
 use crate::ui_kit::{StatusTone, choice_row, expr_row, status_line};
 use egui::RichText;
 use serde_json::{Value, json};
@@ -206,7 +207,7 @@ pub fn rows(app: &mut SolveApp, ui: &mut egui::Ui, f: &mut CouplingForm, inputs:
     form_row(ui, "Animate", |ui| {
         let label = crate::i18n::tr(if f.animate { "ui.joint_stop" } else { "ui.joint_play" });
         let r = crate::ui_kit::button(ui, label, crate::ui_kit::Button::Normal)
-            .on_hover_text(crate::i18n::tr_label("Play the joint's motion in the view"));
+            .backing_on_hover_text(crate::i18n::tr_label("Play the joint's motion in the view"));
         crate::scenario::publish_handle("dialog:Animate", r.rect.center());
         if r.clicked() {
             f.animate = !f.animate;

crates/ui-egui/src/dialogs_dense.rs

@@ -134,13 +134,17 @@ fn fillet_corner_tip() -> String {
 /// radius and narrow it only where the faces run out.
 const FILLET_FITS: [(&str, &str); 3] = [("ui.fillet_fit_exact", "exact"), ("ui.fillet_fit_reduce", "reduce"), ("ui.fillet_fit_taper", "taper")];
 
+/// How two rounds turn where they meet at a sharp corner edge (`turn`): in a mitre (the
+/// default) or swept round the edge.
+const FILLET_TURNS: [(&str, &str); 2] = [("ui.fillet_turn_mitre", "mitre"), ("ui.fillet_turn_swept", "swept")];
+
 /// Which fillet options apply together, exactly as `solid.fillet` takes them (`fillet` in
 /// crates/engine/src/cmd/features.rs):
 ///
-/// | Type          | Face limits (`fit`)     | Corners (`corner`)                  | Setback (`setbacks`) |
-/// |---------------|-------------------------|-------------------------------------|----------------------|
-/// | Constant      | exact, reduce or taper  | tangent; curvature with exact only  | with curvature only  |
-/// | any other     | exact (not sent)        | tangent (not sent)                  | none                 |
+/// | Type          | Face limits (`fit`)     | Corners (`corner`)                  | Setback (`setbacks`) | Turns (`turn`)                  |
+/// |---------------|-------------------------|-------------------------------------|----------------------|---------------------------------|
+/// | Constant      | exact, reduce or taper  | tangent; curvature with exact only  | with curvature only  | mitre; swept without taper, g2  |
+/// | any other     | exact (not sent)        | tangent (not sent)                  | none                 | mitre (not sent)                |
 ///
 /// The dialog shows an option's row only where it applies and sends the option only then, and a
 /// choice that rules another out puts that one back to its default ([`settle_fillet_options`]).
@@ -150,6 +154,8 @@ pub(super) fn fillet_option_applies(extra: &serde_json::Map<String, Value>, key:
     match key {
         "fit" => constant,
         "corner" | "setbacks" => constant && exact,
+        // A swept turn takes an exact or reduced radius and rolling-ball corners.
+        "turn" => constant && extra.get("fit").and_then(Value::as_str) != Some("taper") && extra.get("corner").and_then(Value::as_str) != Some("g2"),
         _ => true,
     }
 }
@@ -159,15 +165,29 @@ pub(super) fn fillet_option_applies(extra: &serde_json::Map<String, Value>, key:
 /// takes the exact radius. A type other than Constant clears both ([`choose_fillet_type`]).
 fn settle_fillet_options(extra: &mut serde_json::Map<String, Value>, changed: &str, setback: &mut Option<String>) {
     let fitted = extra.get("fit").and_then(Value::as_str).is_some_and(|fit| fit != "exact");
+    let tapered = extra.get("fit").and_then(Value::as_str) == Some("taper");
     let patch = extra.get("corner").and_then(Value::as_str) == Some("g2");
+    let swept = extra.get("turn").and_then(Value::as_str) == Some("swept");
     match changed {
         "fit" if fitted => {
             extra.remove("corner");
             extra.remove("setbacks");
             *setback = None;
+            if tapered {
+                extra.remove("turn");
+            }
         }
         "corner" if patch => {
             extra.remove("fit");
+            extra.remove("turn");
+        }
+        "turn" if swept => {
+            extra.remove("corner");
+            extra.remove("setbacks");
+            *setback = None;
+            if tapered {
+                extra.remove("fit");
+            }
         }
         _ => {}
     }
@@ -218,7 +238,7 @@ fn fillet_corner_rows(
             let hint = crate::i18n::format("ui.fillet_setback_hint", &[("factor", &factor)]);
             ui_kit::checked_row(ui, "ui.fillet_setback", &mut text, &hint, warning.as_deref())
         });
-        row.response.on_hover_text(crate::i18n::format("ui.fillet_setback_tip", &[("factor", &factor)]));
+        row.response.backing_on_hover_text(crate::i18n::format("ui.fillet_setback_tip", &[("factor", &factor)]));
         let (accepted, field) = row.inner;
         enter |= accepted;
         if text != shown {
@@ -237,7 +257,7 @@ fn fillet_fit_rows(app: &SolveApp, ui: &mut egui::Ui, extra: &mut serde_json::Ma
     let t = Tokens::get();
     let before = extra.get("fit").cloned();
     let row = ui.scope(|ui| form_row(ui, "ui.fillet_fit", |ui| extra_choice(ui, extra, "fi_fit", "fit", &FILLET_FITS)));
-    row.response.on_hover_text(tr("ui.fillet_fit_tip"));
+    row.response.backing_on_hover_text(tr("ui.fillet_fit_tip"));
     let fit = row.inner;
     if extra.get("fit") != before.as_ref() {
         settle_fillet_options(extra, "fit", setback);
@@ -256,6 +276,17 @@ fn fillet_fit_rows(app: &SolveApp, ui: &mut egui::Ui, extra: &mut serde_json::Ma
     }
 }
 
+/// A Constant radius fillet's Turns row (`turn`): how two rounds turn where they meet at a sharp
+/// corner edge.
+fn fillet_turn_row(ui: &mut egui::Ui, extra: &mut serde_json::Map<String, Value>, setback: &mut Option<String>) {
+    let before = extra.get("turn").cloned();
+    let row = ui.scope(|ui| form_row(ui, "ui.fillet_turn", |ui| extra_choice(ui, extra, "fi_turn", "turn", &FILLET_TURNS)));
+    row.response.on_hover_text(tr("ui.fillet_turn_tip"));
+    if extra.get("turn") != before.as_ref() {
+        settle_fillet_options(extra, "turn", setback);
+    }
+}
+
 /// The most instances a solid pattern makes in one direction (the document's own limit).
 const MAX_PATTERN_INSTANCES: i64 = 1000;
 
@@ -293,6 +324,7 @@ fn choose_fillet_type(extra: &mut serde_json::Map<String, Value>, index: usize,
         extra.remove("fit");
         extra.remove("corner");
         extra.remove("setbacks");
+        extra.remove("turn");
     }
     if index == 2 {
         extra.entry("radius2").or_insert_with(|| json!("1 mm"));
@@ -322,14 +354,14 @@ pub(super) fn rows(app: &mut SolveApp, ctx: &egui::Context, d: &mut Dialog, ui:
             };
             tr(key).to_owned()
         };
-        ui_kit::text(ui, &prompt, ui_kit::Text::Hint("tool")).on_hover_text(&prompt);
+        ui_kit::text(ui, &prompt, ui_kit::Text::Hint("tool")).backing_on_hover_text(&prompt);
         if matches!(&d.kind, Kind::SketchModify(k) if k.previews()) {
             let label = d.active_input().map(|input| tr(input.label)).unwrap_or_else(|| tr("Objects"));
             let step = crate::i18n::format(
                 "dialog.selection_step",
                 &[("step", &(d.active + 1).to_string()), ("total", &d.inputs.len().to_string()), ("input", label)],
             );
-            ui_kit::text(ui, &step, ui_kit::Text::Hint("step")).on_hover_text(tr("dialog.selection_guidance"));
+            ui_kit::text(ui, &step, ui_kit::Text::Hint("step")).backing_on_hover_text(tr("dialog.selection_guidance"));
         }
     }
     let manage_hint = match &d.kind {
@@ -540,10 +572,11 @@ pub(super) fn rows(app: &mut SolveApp, ctx: &egui::Context, d: &mut Dialog, ui:
                     }
                     response
                 })
-                .on_hover_text(tr("ui.fillet_type_choices_tip"));
+                .backing_on_hover_text(tr("ui.fillet_type_choices_tip"));
                 if rtype == 0 {
                     enter |= fillet_corner_rows(ui, &app.session, &mut d.extra, &d.inputs, radius, setback);
                     fillet_fit_rows(app, ui, &mut d.extra, setback);
+                    fillet_turn_row(ui, &mut d.extra, setback);
                 }
             }
             if *chamfer && *ctype == 1 {
@@ -558,7 +591,7 @@ pub(super) fn rows(app: &mut SolveApp, ctx: &egui::Context, d: &mut Dialog, ui:
             ui_kit::section(ui, "fillet_options", "Options", true, |ui| {
                 ui.scope(|ui| ui_kit::checkbox_grid(ui, &mut [("Tangent Chain", chain), ("Preview", &mut d.preview_enabled)], 2))
                     .response
-                    .on_hover_text(tr("ui.fillet_options_tip"));
+                    .backing_on_hover_text(tr("ui.fillet_options_tip"));
             });
             // The radii along the edge, for the two types that take them.
             if !*chamfer && matches!(rtype, 2 | 4) {
@@ -579,12 +612,12 @@ pub(super) fn rows(app: &mut SolveApp, ctx: &egui::Context, d: &mut Dialog, ui:
                             form_row(ui, "Mid Radius", |ui| {
                                 ui.horizontal(|ui| {
                                     ui_kit::fraction_field(ui, position)
-                                        .on_hover_text(tr("Position along the edge, 0 at the start end, 1 at the other"));
+                                        .backing_on_hover_text(tr("Position along the edge, 0 at the start end, 1 at the other"));
                                     let width = (ui.available_width() - t.space_24 - t.space_4).max(0.0);
                                     ui.allocate_ui_with_layout(vec2(width, t.space_24), egui::Layout::left_to_right(egui::Align::Center), |ui| {
                                         enter |= field(ui, r);
                                     });
-                                    if ui_kit::button(ui, "×", ui_kit::Button::Small).on_hover_text(tr("Remove this point")).clicked() {
+                                    if ui_kit::button(ui, "×", ui_kit::Button::Small).backing_on_hover_text(tr("Remove this point")).clicked() {
                                         remove = Some(k);
                                     }
                                 });
@@ -1006,7 +1039,7 @@ fn additional_rows(app: &mut SolveApp, d: &mut Dialog, ui: &mut egui::Ui) -> boo
                         ui.label(format!("{:.2}, {:.2}, {:.2}", p.x, p.y, p.z));
                         // A cylinder's place is its Face pick, cleared there.
                         if *cmd != "solid.cylinder"
-                            && ui_kit::button(ui, "×", ui_kit::Button::Small).on_hover_text(tr("Place at the origin instead")).clicked()
+                            && ui_kit::button(ui, "×", ui_kit::Button::Small).backing_on_hover_text(tr("Place at the origin instead")).clicked()
                         {
                             *at = None;
                         }
@@ -1281,13 +1314,46 @@ mod tests {
         assert!(scenario::handle_at("dialog:ui.fillet_fit").is_none(), "a fitted radius is for Constant radius only");
     }
 
+    /// Turns sends `turn: swept` with a Constant radius only, and a choice it rules out (a
+    /// narrowed radius, a curvature corner) puts the other back: Swept and those never go
+    /// together.
+    #[test]
+    fn turns_maps_to_turn_and_rules_out_what_a_swept_corner_does_not_take() {
+        let mut h = fillet_harness();
+        set_edges(&mut h, 3);
+        assert!(scenario::handle_at("dialog:ui.fillet_turn").is_some());
+        assert!(parameters(&h).get("turn").is_none(), "Mitre is the default, not sent");
+        choose(&mut h, "ui.fillet_turn", "ui.fillet_turn_swept");
+        assert_eq!(parameters(&h)["turn"], json!("swept"));
+        choose(&mut h, "ui.fillet_fit", "ui.fillet_fit_reduce");
+        assert_eq!((parameters(&h)["turn"].clone(), parameters(&h)["fit"].clone()), (json!("swept"), json!("reduce")));
+        choose(&mut h, "ui.fillet_fit", "ui.fillet_fit_taper");
+        assert!(parameters(&h).get("turn").is_none(), "a narrowed radius puts Turns back to Mitre");
+        choose(&mut h, "ui.fillet_turn", "ui.fillet_turn_swept");
+        assert!(parameters(&h).get("fit").is_none(), "Swept puts Face limits back to Exact radius");
+        choose(&mut h, "ui.corners", Continuity::G2.label_id());
+        assert!(parameters(&h).get("turn").is_none(), "a curvature corner puts Turns back to Mitre");
+        choose(&mut h, "ui.fillet_turn", "ui.fillet_turn_swept");
+        assert!(parameters(&h).get("corner").is_none(), "Swept puts Corners back to Tangent");
+        choose(&mut h, "ui.fillet_turn", "ui.fillet_turn_mitre");
+        assert!(parameters(&h).get("turn").is_none(), "Mitre is not sent");
+        choose(&mut h, "ui.fillet_turn", "ui.fillet_turn_swept");
+        choose(&mut h, "Type", "Chord length");
+        assert!(parameters(&h).get("turn").is_none() && scenario::handle_at("dialog:ui.fillet_turn").is_none(), "Turns is for Constant radius only");
+    }
+
     /// The dialog follows the option model (`fillet_option_applies`): through every type, fit and
     /// corner choice, in either order, each option it shows is one the others allow, and the
     /// command it builds is never refused for its options (`solid.fillet` runs it on a copy of
     /// the design). A choice that rules another out resets that one, visibly.
     #[test]
     fn no_reachable_fillet_option_state_is_refused_for_its_options() {
-        let refused_for_options = |e: &str| e.contains("take a constant radius") || e.contains("is built for") || e.contains("are built for");
+        let refused_for_options = |e: &str| {
+            e.contains("take a constant radius")
+                || e.contains("is built for")
+                || e.contains("are built for")
+                || e.contains(solidcraft_engine::doc::SWEPT_TAKES)
+        };
         // Each distinct command is run once.
         let ran = std::cell::RefCell::new(std::collections::BTreeSet::new());
         let check = |h: &Harness, what: &str| {

crates/ui-egui/src/dialogs_insert_drawing.rs

@@ -2,6 +2,7 @@
 //! its middle goes, its size in millimetres or as a factor, and an angle) with a live preview,
 //! and OK adds it (#2605, #3443).
 
+use crate::ui_kit::BackingTooltipExt as _;
 use serde_json::{Value, json};
 
 use crate::SolveApp;
@@ -46,7 +47,7 @@ pub fn title(p: &Place) -> &'static str {
 pub fn rows(ui: &mut egui::Ui, p: &mut Place) {
     let name = std::path::Path::new(&p.path).file_name().map(|n| n.to_string_lossy().to_string()).unwrap_or_else(|| p.path.clone());
     form_row(ui, "File", |ui| {
-        ui.label(name).on_hover_text(&p.path);
+        ui.label(name).backing_on_hover_text(&p.path);
     });
     for (label, v, handle) in [("X", &mut p.x, "dialog:insert:x"), ("Y", &mut p.y, "dialog:insert:y")] {
         form_row(ui, label, |ui| {

crates/ui-egui/src/dialogs_library.rs

@@ -1,6 +1,7 @@
 //! The first local appearance-library consumer, inside the existing Appearance panel.
-#[cfg(not(target_arch = "wasm32"))]
 use crate::dialogs_appearance::selected_params;
+#[cfg(not(target_arch = "wasm32"))]
+use crate::ui_kit::BackingTooltipExt as _;
 use crate::{SolveApp, dialogs_appearance::Ap, selection::SelInput, ui_kit};
 use serde_json::json;
 use solidcraft_engine::io::catalog::Catalog;
@@ -221,7 +222,7 @@ fn import_rows(app: &mut SolveApp, ui: &mut egui::Ui, k: &mut Ap, inputs: &[SelI
                             }
                             let button =
                                 ui_kit::list_picker(ui, &entry.id, entry.definition.name(), k.local.selected.as_deref() == Some(entry.id.as_str()))
-                                    .on_hover_text(format!(
+                                    .backing_on_hover_text(format!(
                                         "{} · {} · {}",
                                         entry.id,
                                         entry.provenance.license,

crates/ui-egui/src/dialogs_motion.rs

@@ -3,6 +3,7 @@
 //! show while open (a study's pose, an explosion) is display only: pending occurrence moves,
 //! computed on a scratch copy of the design and put back when the dialog closes.
 
+use crate::ui_kit::BackingTooltipExt as _;
 use crate::ui_kit::{choice_row, expr_row, text_row};
 use std::collections::BTreeMap;
 
@@ -205,7 +206,7 @@ fn transport(ui: &mut egui::Ui, what: Transport, tip: &str) -> egui::Response {
             p.add(bar(c.x + 6.0));
         }
     }
-    resp.on_hover_text(crate::i18n::tr_label(tip))
+    resp.backing_on_hover_text(crate::i18n::tr_label(tip))
 }
 
 /// Study `key` as the Motion Study dialog edits it: (id, name, steps, keys as tracks with values
@@ -473,7 +474,7 @@ pub fn rows(app: &mut SolveApp, ui: &mut egui::Ui, k: &mut Mo, inputs: &mut [Sel
                             let _ = app.run("contact.edit", json!({"set": n, "suppressed": !off}));
                         }
                         if crate::ui_kit::button(ui, crate::i18n::tr_label("×"), crate::ui_kit::Button::Small)
-                            .on_hover_text(crate::i18n::tr_label("Delete the set"))
+                            .backing_on_hover_text(crate::i18n::tr_label("Delete the set"))
                             .clicked()
                         {
                             let _ = app.run("contact.edit", json!({"set": n, "delete": true}));
@@ -641,7 +642,7 @@ fn motion_study_rows(app: &mut SolveApp, ui: &mut egui::Ui, k: &mut Mo, inputs:
                 let width = (ui.available_width() - t.control_height - t.space_8).max(0.0);
                 ui.allocate_ui(vec2(width, t.control_height), |ui| combo(ui, &format!("ms_joint{ti}"), &refs, &mut pos));
                 if crate::ui_kit::button(ui, crate::i18n::tr_label("×"), crate::ui_kit::Button::Small)
-                    .on_hover_text(crate::i18n::tr_label("Remove the track"))
+                    .backing_on_hover_text(crate::i18n::tr_label("Remove the track"))
                     .clicked()
                 {
                     remove = Some(ti);
@@ -671,7 +672,7 @@ fn motion_study_rows(app: &mut SolveApp, ui: &mut egui::Ui, k: &mut Mo, inputs:
         ui.vertical(|ui| {
             ui.horizontal(|ui| {
                 if crate::ui_kit::button(ui, crate::i18n::tr_label("Key here"), crate::ui_kit::Button::Small)
-                    .on_hover_text(crate::i18n::tr_label("Add a key at this step with the joint's value now"))
+                    .backing_on_hover_text(crate::i18n::tr_label("Add a key at this step with the joint's value now"))
                     .clicked()
                     && !tr.points.iter().any(|(s, _)| *s == now)
                 {
@@ -699,7 +700,7 @@ fn motion_study_rows(app: &mut SolveApp, ui: &mut egui::Ui, k: &mut Mo, inputs:
     ui.vertical(|ui| {
         ui.horizontal(|ui| {
             if crate::ui_kit::button(ui, crate::i18n::tr_label("Add Key"), crate::ui_kit::Button::Normal)
-                .on_hover_text(crate::i18n::tr_label("Key a joint's value at this step"))
+                .backing_on_hover_text(crate::i18n::tr_label("Key a joint's value at this step"))
                 .clicked()
                 && let Some((ji, _, kind)) = moving.first()
             {
@@ -707,7 +708,7 @@ fn motion_study_rows(app: &mut SolveApp, ui: &mut egui::Ui, k: &mut Mo, inputs:
                 tracks.push(Track { joint: *ji, index: 0, points: vec![(now, format!("0 {unit}"))] });
             }
             export = crate::ui_kit::button(ui, crate::i18n::tr_label("Export Animation…"), crate::ui_kit::Button::Normal)
-                .on_hover_text(crate::i18n::tr_label("Save the study as an animated GIF, seen as the viewport shows it"))
+                .backing_on_hover_text(crate::i18n::tr_label("Save the study as an animated GIF, seen as the viewport shows it"))
                 .clicked();
         });
     });