chore: release 0.6.1

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
docs: agents and annotations guides, specs, mock-ups, 0.6.1 checks
2026-10-22 05:37:26 -03:00 · 2026-10-22 05:37:20 -03:00 · 2026-10-22 05:37:20 -03:00 · 2026-10-21 22:43:18 -03:00 · 2026-10-21 22:43:11 -03:00 · 2026-10-21 22:43:11 -03:00
137 changed files with 16365 additions and 134 deletions
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+checksum = "e6c10a63a0fa32252be49d21e7709d4d4baf8d231c2dbce1eaa8141b9b127d88"
+dependencies = [
+ "ppv-lite86",
+ "rand_core 0.6.4",
+]
+
 [[package]]
 name = "rand_chacha"
 version = "0.9.0"
@@ -3041,6 +3500,15 @@ dependencies = [
 "rand_core 0.9.5",
 ]

+[[package]]
+name = "rand_core"
+version = "0.6.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ec0be4795e2f6a28069bec0b5ff3e2ac9bafc99e6a9a7dc3547996c5c816922c"
+dependencies = [
+ "getrandom 0.2.17",
+]
+
 [[package]]
 name = "rand_core"
 version = "0.9.5"
@@ -3460,6 +3928,38 @@ dependencies = [
 "tiny-skia 0.11.4",
 ]

+[[package]]
+name = "secret-service"
+version = "4.0.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e4d35ad99a181be0a60ffcbe85d680d98f87bdc4d7644ade319b87076b9dbfd4"
+dependencies = [
+ "aes",
+ "cbc",
+ "futures-util",
+ "generic-array",
+ "hkdf",
+ "num",
+ "once_cell",
+ "rand 0.8.8",
+ "serde",
+ "sha2",
+ "zbus",
+]
+
+[[package]]
+name = "security-framework"
+version = "2.11.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "897b2245f0b511c87893af39b033e5ca9cce68824c4d7e7630b5a1d339658d02"
+dependencies = [
+ "bitflags 2.13.2",
+ "core-foundation 0.9.4",
+ "core-foundation-sys",
+ "libc",
+ "security-framework-sys",
+]
+
 [[package]]
 name = "security-framework"
 version = "3.7.0"
@@ -3560,6 +4060,17 @@ dependencies = [
 "serde_core",
 ]

+[[package]]
+name = "serde_repr"
+version = "0.1.21"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8d3b1629de253c70a0508c3899572da79ca359fdab27c7920ff00406df418906"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn 3.0.7",
+]
+
 [[package]]
 name = "serde_spanned"
 version = "1.1.2"
@@ -3592,6 +4103,17 @@ dependencies = [
 "digest",
 ]

+[[package]]
+name = "sha2"
+version = "0.10.9"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a7507d819769d01a365ab707794a4084392c824f54a7a6a7862f8c3d0892b283"
+dependencies = [
+ "cfg-if",
+ "cpufeatures 0.2.17",
+ "digest",
+]
+
 [[package]]
 name = "shlex"
 version = "2.0.1"
@@ -3801,6 +4323,12 @@ dependencies = [
 "float-cmp",
 ]

+[[package]]
+name = "subtle"
+version = "2.6.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "13c2bddecc57b384dee18652358fb23172facb8a2c51ccc10d74c157bdea3292"
+
 [[package]]
 name = "svgtypes"
 version = "0.16.1"
@@ -3860,10 +4388,10 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "32497e9a4c7b38532efcdebeef879707aa9f794296a4f0244f6f69e9bc8574bd"
 dependencies = [
 "fastrand",
- "getrandom 0.3.4",
+ "getrandom 0.4.3",
 "once_cell",
 "rustix 1.1.5",
- "windows-sys 0.52.0",
+ "windows-sys 0.61.2",
 ]

 [[package]]
@@ -4241,6 +4769,17 @@ version = "1.20.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "b6f5e870be6c3b371b77fe0ee0bafb859fa4964b4404c27de1d380043c4dda20"

+[[package]]
+name = "uds_windows"
+version = "1.2.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f2f6fb2847f6742cd76af783a2a2c49e9375d0a111c7bef6f71cd9e738c72d6e"
+dependencies = [
+ "memoffset",
+ "tempfile",
+ "windows-sys 0.60.2",
+]
+
 [[package]]
 name = "unicode-bidi"
 version = "0.3.18"
@@ -5253,6 +5792,16 @@ version = "0.3.11"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "163b33ed8786455e2fa5d72f554057ce3f3182425434f756cd39c99839d88e23"

+[[package]]
+name = "xdg-home"
+version = "1.3.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ec1cdab258fb55c0da61328dc52c8764709b249011b2cad0454c72f0bf10a1f6"
+dependencies = [
+ "libc",
+ "windows-sys 0.59.0",
+]
+
 [[package]]
 name = "xkbcommon-dl"
 version = "0.4.2"
@@ -5307,6 +5856,62 @@ dependencies = [
 "synstructure",
 ]

+[[package]]
+name = "zbus"
+version = "4.4.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "bb97012beadd29e654708a0fdb4c84bc046f537aecfde2c3ee0a9e4b4d48c725"
+dependencies = [
+ "async-broadcast",
+ "async-process",
+ "async-recursion",
+ "async-trait",
+ "enumflags2",
+ "event-listener",
+ "futures-core",
+ "futures-sink",
+ "futures-util",
+ "hex",
+ "nix 0.29.0",
+ "ordered-stream",
+ "rand 0.8.8",
+ "serde",
+ "serde_repr",
+ "sha1",
+ "static_assertions",
+ "tracing",
+ "uds_windows",
+ "windows-sys 0.52.0",
+ "xdg-home",
+ "zbus_macros",
+ "zbus_names",
+ "zvariant",
+]
+
+[[package]]
+name = "zbus_macros"
+version = "4.4.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "267db9407081e90bbfa46d841d3cbc60f59c0351838c4bc65199ecd79ab1983e"
+dependencies = [
+ "proc-macro-crate",
+ "proc-macro2",
+ "quote",
+ "syn 2.0.119",
+ "zvariant_utils",
+]
+
+[[package]]
+name = "zbus_names"
+version = "3.0.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "4b9b1fef7d021261cc16cba64c351d291b715febe0fa10dc3a443ac5a5022e6c"
+dependencies = [
+ "serde",
+ "static_assertions",
+ "zvariant",
+]
+
 [[package]]
 name = "zerocopy"
 version = "0.8.62"
@@ -5353,6 +5958,20 @@ name = "zeroize"
 version = "1.9.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "e13084392c5e4bc371903e2935a5eaeed24905a7511356b883835e18a78f6879"
+dependencies = [
+ "zeroize_derive",
+]
+
+[[package]]
+name = "zeroize_derive"
+version = "1.5.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "3c50655cbb0fe3fc43170059e702f1ce5e19b84cec58dc87b037a09935c2f328"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn 2.0.119",
+]

 [[package]]
 name = "zerotrie"
@@ -5413,3 +6032,40 @@ checksum = "27bc9d5b815bc103f142aa054f561d9187d191692ec7c2d1e2b4737f8dbd7296"
 dependencies = [
 "zune-core",
 ]
+
+[[package]]
+name = "zvariant"
+version = "4.2.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "2084290ab9a1c471c38fc524945837734fbf124487e105daec2bb57fd48c81fe"
+dependencies = [
+ "endi",
+ "enumflags2",
+ "serde",
+ "static_assertions",
+ "zvariant_derive",
+]
+
+[[package]]
+name = "zvariant_derive"
+version = "4.2.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "73e2ba546bda683a90652bac4a279bc146adad1386f25379cf73200d2002c449"
+dependencies = [
+ "proc-macro-crate",
+ "proc-macro2",
+ "quote",
+ "syn 2.0.119",
+ "zvariant_utils",
+]
+
+[[package]]
+name = "zvariant_utils"
+version = "2.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c51bcff7cc3dbb5055396bcf774748c3dab426b4b8659046963523cee4808340"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn 2.0.119",
+]
@@ -1,6 +1,6 @@
 [package]
 name = "papercraft"
-version = "0.5.0"
+version = "0.6.1"
 edition = "2024"
 rust-version = "1.95"
 description = "A native infinite-canvas app for planning, working and sketching"
@@ -93,6 +93,10 @@ axum = { version = "0.8", default-features = false, features = ["http1", "tokio"
 tokio-util = "0.7"
 # Shared-project sync; the system TLS stack so https servers work without bundling one.
 reqwest = { version = "0.13", default-features = false, features = ["native-tls"] }
+# Anthropic API key in the OS keychain (chat API backend). Linux uses the Secret Service (persistent; keyutils is not).
+# libc: SIGINT to the spawned chat CLIs.
+keyring = { version = "3", default-features = false, features = ["apple-native", "windows-native", "sync-secret-service", "crypto-rust"] }
+libc = "0.2"

 # Browser build (`src/web.rs`): canvas + WebGPU/WebGL surface, DOM events instead of winit.
 [target.'cfg(target_arch = "wasm32")'.dependencies]
@@ -1,6 +1,6 @@
 # Progress

-Last updated: 2026-10-21.
+Last updated: 2026-10-22.

 ## Phase 3: local-first design and whiteboard tool

@@ -76,6 +76,24 @@ are credited in `THIRD_PARTY.md`.
 * **Not carried over**: comments, design tokens, AI image generation, video export, teams;
  moving layers between pages; remote image URLs (see README Known gaps).

+### 2026-10-22: 0.6.1 (agents via ACP, annotations)
+
+* Agents are found through the login shell's PATH (read once at startup, 3 s limit, merged with the app PATH and the usual folders), so an app opened from the Dock finds Claude Code, Codex and the rest. No install instructions anywhere; a missing agent shows Not found with Set path… and Docs.
+* ACP backend (`src/chat/acp.rs`): any agent that speaks the Agent Client Protocol over stdio, with PaperCraft's MCP server, streamed updates, permission flow, cancel and load. Registry as data in `src/chat/agents.rs`: native agents found on PATH, npx agents off until enabled, custom agents by name, command and arguments. Verified here: OpenCode works; Gemini CLI's server currently refuses ACP clients; Cursor needs `cursor-agent login`; Pi works through `pi-acp` after enabling.
+* Agent panel over the chat column (Detected, Enable via npx, Not found, API endpoints, Custom, search), a Connect an agent setup card, a sign-in card, and multiple `@ Selection` chips.
+* Settings → Chat redesigned: one agents list with details, endpoints, defaults, scrolling page on one label grid.
+* Send bug: a turn that cannot start keeps the typed text and shows an error row with Retry, never a silent no-op (`a_failed_start_keeps_the_text_and_shows_an_error`).
+* Annotations: notes with leader lines on a page, six categories with keys (style comes only from the category), project and per-page templates with built-ins and a Customize modal, view modes (⌘⇧A), Annotate tool (N), side view, inspector section, Annotate with AI, six MCP tools (`annotate` batches), and comments in `get_design_spec` and the code exports. Exports and Present leave annotations out.
+* Evidence: `src/chat/{path,agents,acp}.rs`, `src/ui/{chat_agents,annotations,annotations_canvas}.rs`, `src/model/annotation.rs`, `src/editor/annotations.rs`, `src/mcp/tools.rs`, `tests/annotations*.rs`, `specs/chat-agents/`, `specs/annotations/`, `docs/chat.md`, `docs/annotations.md`.
+
+### 2026-10-21: Chat mode
+
+* Chat layout next to the canvas (⌘J, `Design | Chat`), with three backends: Claude Code and Codex through their CLIs (`claude -p` stream-json, `codex exec --json`) against the app's MCP server, and the Anthropic API with a key in the OS credential store. One event stream for all three; tool calls run through the same MCP dispatch, so runs, review and revert behave as before.
+* Thread: markdown replies, thinking row, tool cards, step groups, plan from `TodoWrite`, approval for destructive tools on the API backend, run checkpoints with Restore to here, usage line and context meter, `@ Selection` and image attachments, Stop.
+* Chats live in the project's `chats/` folder. Settings → Chat holds CLI paths, the default backend and the API key.
+* Offline CLI fix: an offline save writes no camera, and a top-level shape created without a position goes to the next free spot instead of the origin.
+* Evidence: `src/chat/`, `src/ui/chat.rs`, `src/ui/chat_msgs.rs`, `src/ui/chat_md.rs`, `src/ui/settings.rs`, `src/mcp/exec.rs`, `tests/fixtures/chat/`, `specs/chat/`, `docs/chat.md`.
+
 ### 2026-10-21: Agent runs and change review

 * Agent editing calls group into runs, snapshot each edited page as `Before agent run N`, and end on 30 seconds idle, `finish_working_on_nodes`, or project switch. Runs persist under `runs/` and keep the newest 50.
@@ -90,7 +90,7 @@ Projects live in `~/Documents/papercraft/<name>/` (`project.json`, one JSON file

 ## Agents

-PaperCraft exposes **61 tools** (`src/mcp/tools.rs`) three ways. They run the same code inside the app.
+PaperCraft exposes **67 tools** (`src/mcp/tools.rs`) three ways. They run the same code inside the app.

 | Way | Notes |
 |---|---|
@@ -136,6 +136,20 @@ EOF
  <sub><code>preview.png</code> from an offline shell script, with no app running.</sub>
 </p>

+### Chat
+
+Chat mode (⌘J, or `Design | Chat` in the top bar) puts a conversation next to the canvas. It runs Claude Code and Codex through their CLIs, any agent that speaks the Agent Client Protocol (ACP, such as OpenCode, Gemini CLI or Cursor) found on your PATH, or the Anthropic API with your own key. It shows tool calls, checkpoints and run review in the thread. Chats are saved in the project's `chats/` folder. See [docs/chat.md](docs/chat.md).
+
+<p align="center">
+  <img src="docs/screenshots/readme/chat.png" alt="Chat mode: the chat column on the left shows a finished agent run with its Review, Revert and Accept actions, and the canvas on the right" width="100%">
+  <br>
+  <sub>Chat mode with a finished agent run: review, revert or accept from the thread.</sub>
+</p>
+
+### Annotations
+
+Annotations are notes that explain a design in place: business rules, behaviour, data sources, accessibility and dev notes, each a numbered card with a leader line to its layer. Categories set the look, templates say which notes a page wants (product spec, dev handoff, accessibility review and more), and the view cycles between full notes, badges and hidden with ⌘⇧A. Exports and Present mode leave them out. Agents add them in one `annotate` call. See [docs/annotations.md](docs/annotations.md).
+
 ### Skills

 [`skills/`](skills) holds agent skills: `papercraft` (the build, screenshot, lint, fix loop and tool cheat sheet), `papercraft-design` (design-quality rules) and `papercraft-critique`. [docs/agents.md](docs/agents.md) is the full guide: install, registering with agents, scripts, runs and review, safety. [docs/design-system.md](docs/design-system.md) covers variables, components and libraries.
@@ -212,6 +226,8 @@ The scenario tests drive the editor with synthetic pointer and keyboard events;
 | ⌘⌥⇧V | Variables | ⌘⌥C / ⌘⌥V | Copy / paste properties |
 | ⌘= / ⌘- / ⇧0 | Zoom in / out / 100% | ⇧1 / ⇧2 | Zoom to fit / selection |
 | PageUp / PageDown | Previous / next page | ⌘\\ | Show / hide UI |
+| ⌘J | Design / Chat mode | ⌘L | Add selection to chat (Chat mode) |
+| N | Annotate tool | ⌘⇧A | Annotations: full, badges, hidden |

 Draw a frame around existing shapes and it adopts them; dragging a layer into or out of a frame re-parents it. Hold ⌘ while dragging to suspend snapping.

@@ -226,7 +242,7 @@ Draw a frame around existing shapes and it adopts them; dragging a layer into or
 * **Variables:** gradients keep fixed colors; there are no text styles and no component variants or properties.
 * **Booleans are destructive:** the result is a new vector path with flattened curves.
 * **`write_html`** ignores margin, tables and transforms (it reports them as `ignoredStyles`) and does not fetch remote images; pass a local path or a `data:` URI.
-* **Agents:** one project is open at a time in the app, and `move_nodes` stays on one page. There is no in-app prompt box; agents run outside and connect over MCP or the CLI.
+* **Agents:** one project is open at a time in the app, and `move_nodes` stays on one page. The in-app Chat mode runs Claude Code, Codex, ACP agents or your own Anthropic key. Agents that are not in Chat connect over MCP or the CLI.
 * **Sharing** has no live presence (cursors, selections) yet.
 * **Pen pressure** is simulated from stroke velocity on macOS tablets, because winit 0.30 does not expose it for mouse-like pen events.
 * **Releases** cover macOS (Apple silicon) and Linux x86_64. Windows packaging scripts exist but are not part of releases.
@@ -2,7 +2,7 @@

 PaperCraft is an early alpha: a local-first infinite-canvas design app that agents can drive. This
 file lists what is still missing, in priority order, with an honest status. Done items are checked
-against `src/mcp/tools.rs` and the UI code (2026-10-12); rows 7, 8, 12, 15, 23, 25, 32, 34, 39, 40, 45, 46 and section 6 were updated 2026-10-21. Milestone history is in
+against `src/mcp/tools.rs` and the UI code (2026-10-12); rows 7, 8, 12, 15, 23, 25, 32, 34, 39, 40, 44, 45, 46 and section 6 were updated 2026-10-21; rows 15, 47 and 48 on 2026-10-22. Milestone history is in
 [PROGRESS.md](PROGRESS.md); known rendering and import limits are in the README.

 Status: **done** (works today), **partial** (some of it works), **todo**.
@@ -32,7 +32,7 @@ Agents can already build a design system through the tools; people cannot yet ma

 | # | Item | Status | Notes |
 |---|---|---|---|
-| 15 | MCP and CLI tool surface | **done** | 61 tools, one undo step per call, `papercraft-cli list / schema / call`. |
+| 15 | MCP and CLI tool surface | **done** | 67 tools, one undo step per call, `papercraft-cli list / schema / call`. |
 | 16 | Agent skills | **done** | `skills/papercraft` and `skills/papercraft-design`. |
 | 17 | Accessibility annotations | todo | Reading order, roles and alt text on layers, checked by the linter. |
 | 18 | Code export from frames | **done** | `get_jsx` supports `format: "inline"`, `"tailwind"` (Tailwind utility classes), and `"html"` (HTML + CSS rules with `:root` variables). |
@@ -84,5 +84,12 @@ Spec: [specs/agent-runs/spec.md](specs/agent-runs/spec.md), tasks: [specs/agent-
 | 41 | Agent presence on the canvas | todo | Outline the node a tool call touches, label it, pause or stop the run. |
 | 42 | `get_context` tool | todo | Selection, variables, nearby components and lint summary in one call, so an agent orients in one round trip. |
 | 43 | Comments assigned to agents | todo | `@agent` in a thread triggers an edit and a reply. Needs threaded comments. |
-| 44 | In-app prompt bar | todo | Run a prompt on the selection through the user's own key or local CLI. Largest scope: provider config, key storage, cost. |
+| 44 | In-app prompt bar | **done** | Chat mode: Claude Code, Codex or your own Anthropic key; see `docs/chat.md`. |
 | 45 | Correct tool annotations | **done** | `lint_design` no longer sends `readOnlyHint`; `fix: true` edits are classified. |
+
+## 7. Annotations and chat agents
+
+| # | Item | Status | Notes |
+|---|---|---|---|
+| 47 | Design annotations | **done** | Notes with leader lines and categories, templates per project and page, view modes (⌘⇧A), Annotate tool (N), side view, inspector section, six MCP tools; see `docs/annotations.md`. |
+| 48 | ACP agents in Chat | **done** | Any ACP agent on the PATH (OpenCode works; Gemini CLI refuses ACP clients for now; Cursor needs `cursor-agent login`), npx agents after enabling, custom agents; see `docs/chat.md`. |
@@ -1,6 +1,6 @@
 # Driving PaperCraft with agents

-PaperCraft exposes one set of 61 tools three ways. They all run the same code inside the app, so an agent sees what you see and every call is one undo step.
+PaperCraft exposes one set of 67 tools three ways. They all run the same code inside the app, so an agent sees what you see and every call is one undo step.

 | Way | Use it when | Needs the app running |
 |---|---|---|
@@ -8,6 +8,8 @@ PaperCraft exposes one set of 61 tools three ways. They all run the same code in
 | MCP over stdio, `papercraft-mcp` | the client only starts stdio servers | for calls; `tools/list` works offline |
 | Shell, `papercraft-cli` | the agent has a terminal and you want no tool schemas in its context | for `call`; `list`, `schema` and `icons` work offline |

+If you would rather talk to the agent inside the app, Chat mode (⌘J, or `Design | Chat` in the top bar) is the in-app alternative. It runs Claude Code or Codex through their CLIs against the same MCP server, ACP agents such as OpenCode or Gemini CLI, or the Anthropic API with your own key, and keeps the conversation next to the canvas, with the same runs, review and revert. The setup and the thread are in [chat.md](chat.md). The rest of this guide covers driving the app from your own terminal or agent client.
+
 ## Install

 1. Get the app and the tools: the DMG and the `papercraft-cli` zip from the [releases](https://git.marcospaulo.dev.br/masi/papercraft/releases), or `cargo build --release` (binaries `papercraft`, `papercraft-cli`, `papercraft-mcp` in `target/release/`).
@@ -110,6 +112,16 @@ EOF
 * Components: `get_components` lists mains of every page and enabled library with a `componentKey`; `create_instance` and `swap_instance` accept a main from any page or library (`componentId` or `componentKey`).
 * Libraries: `publish_library`, `list_libraries`, `enable_library`, `update_library`, `disable_library`. They work offline too, on the project store.

+## Annotation tools
+
+* `annotate {pageId?, notes: [{node, text, type?}]}` adds many notes in one undo step. `node` is a node id or an exact layer name; the first line of `text` is the label and the rest the body; `type` is a category key (default `rule`) that the page's template must enable. Placement is automatic.
+* `get_annotation_template {pageId?}` returns the allowed types with their guidance and fields. Call it once before `annotate`.
+* `set_annotation_template {template, scope?: "page" | "project", pageId?}` switches the template by id or name.
+* `get_annotations {nodeId?, pageId?, full?}` reads notes as `[number, node, type, text]` rows.
+* `update_annotation {id | ref, text?, type?}` and `delete_annotations {ids}` take ids or references such as `Sign in #3`.
+
+See [annotations.md](annotations.md) for categories, templates and what the notes look like.
+
 ## Safety

 The server listens on loopback only, rejects requests that carry an `Origin` header (browsers) and foreign `Host` headers. Anything on your machine that can reach `127.0.0.1:29980` can edit the open project, so do not forward the port. Undo (⌘Z, or the `undo` tool) reverts any agent edit.
@@ -0,0 +1,128 @@
+# Annotations
+
+An annotation is a note that explains a design in place: a business rule, a behaviour, where the data comes from, an accessibility gap. Each note is a small card with a number, a category, a label and an optional body, joined to its layer by a leader line. Teams use them for review and handoff, and turn them off for presenting.
+
+Annotations live on a page and are saved with it (the `annotations` list in the page file). Pages without any load and save exactly as before. Categories and templates are project-wide and live in `design.json`.
+
+## Categories
+
+Every note has one category. The category is the only thing that sets how a note looks: its icon, colour and badge come from the category, and a note stores none of them. Change a category's colour or icon and every note in it changes.
+
+Each category has a short type key. Agents and the Annotate popover use the key; the UI shows the name.
+
+| Key | Name | Icon | Colour | Use for |
+|---|---|---|---|---|
+| `rule` | Business rule | scale | violet `#7c5cff` | the rule or constraint the part enforces |
+| `behaviour` | Behaviour | zap | blue `#2f80ed` | states, transitions, edge cases |
+| `content` | Content | type | green `#1fa87a` | copy, tone, length |
+| `data` | Data | database | amber `#e08a1e` | where a value comes from |
+| `a11y` | Accessibility | accessibility | pink `#d94f8a` | focus, labels, contrast, reading order |
+| `dev` | Dev note | code | grey `#6b7280` | implementation notes for engineers |
+
+You can add categories, rename them, change their key, colour and icon, and write guidance for each one in the Customize modal. A custom category gets a key too.
+
+## Templates
+
+A template says which kinds of notes a page wants, and what each note should contain. The project has a default template; a page can use its own instead.
+
+Built-in templates are editable copies, not locked. Each category in a template has enabled or not, guidance (a short prompt for what the note should say) and optional fields (structured lines such as `Owner`).
+
+| Template | Categories | Fields |
+|---|---|---|
+| Product spec | rule, behaviour, content, data | none |
+| Dev handoff | behaviour, data, dev, a11y | none |
+| Accessibility review | a11y | Issue, WCAG, Fix |
+| Content review | content | Tone, Max length |
+| Minimal | rule | none |
+
+Pick the project default or "This page" from the template chips at the top of the Annotations side view. Built-ins can be reset; custom templates can be deleted. Duplicate copies any template so you can change it.
+
+**Customize…** (side view) opens the template editor: name, display (full notes or badges), the enabled categories, the guidance and fields of each. Changes to categories apply to the whole project.
+
+The Annotate popover offers only the enabled categories of the active template, and shows each field as a labelled line. A field is stored as a `Name: value` line at the top of the note's body. Agents get the same rule: `annotate` refuses a type the template disables and lists the allowed keys.
+
+## View modes
+
+Three levels, all view state. They are not saved in the design and not undoable.
+
+* **Full**: every note shows its label and the first lines of its body.
+* **Badges**: only the number badges are shown.
+* **Hidden**: nothing is drawn.
+
+`⌘⇧A` (View → Annotations) cycles Full → Badges → Hidden → Full. The starting mode follows the template's display setting until you change it.
+
+Two finer controls:
+
+* **Per note**: collapse a note to its number badge; click the badge to expand it again.
+* **Per category**: show or hide a category from the category filter in the side view.
+
+Annotations are drawn as an overlay on the canvas only. Exports (PNG, SVG, PDF) and Present mode never include them. There is no option to include them in an export yet.
+
+## Annotate tool
+
+Press `N` for the Annotate tool, then click a layer. The New annotation popover opens beside it with:
+
+* Category, from the template's enabled categories.
+* Label, up to 40 characters. The popover shows the count.
+* The template's fields, if any.
+* A note, in Markdown.
+
+Save creates the note with its leader line to the layer's side; Cancel discards it. You can also select layers, right-click, and choose **Annotate**.
+
+Each note's leader line starts at the note card and ends at the anchor on the target. The card and the anchor are stored relative to the target, so moving or resizing the layer keeps the note attached. Drag a card to move it; the line re-routes.
+
+If the target is deleted, the note stays where it was in the side view's **Detached** group, with a warning badge.
+
+## Annotations side view
+
+The side view lists the page's notes:
+
+* Grouped by top-level frame, plus **Page** (notes on no frame) and **Detached**.
+* Each row shows the number, the category chip and the label. Click a row to select the layer and zoom to it.
+* The category filter shows or hides categories.
+* Edit a note inline, or delete it. Edits are one undo step each.
+* **Add annotation** opens the popover for the current selection.
+* **Annotate with AI** puts a prompt in the Chat composer, unsent, with the selected frame (or the page) as a chip. The prompt asks the agent to read the template with `get_annotation_template` and add all the notes in one `annotate` call. It needs a saved project and Chat mode.
+
+Numbers run per frame in reading order (top to bottom, then left to right), so a frame reads 1, 2, 3. Notes on no frame are numbered after that, from 1.
+
+## Inspector
+
+When a single layer is selected, the inspector has an Annotations section. It lists that layer's notes, with edit and delete, and an Add annotation button. The note's anchor is one of the four sides of the target (Top, Right, Bottom, Left) with a position along it.
+
+## Agents
+
+Agents work with notes through six MCP tools, all in `src/mcp/tools.rs`. They are one undo step per call and appear in `edits_doc`, so a run that only adds notes still gets a Review card (a "Notes" group, counted as added, changed or removed), and Revert removes them.
+
+| Tool | What it does |
+|---|---|
+| `get_annotation_template` | Reads the template: `[type key, guidance, field names]` for each enabled type. Call it once before `annotate`. |
+| `set_annotation_template` | Switches the template by id or name, for one page (default) or the project (`scope: "project"`). |
+| `annotate` | Adds many notes at once. Each note names a node id or an exact layer name on the page, a `text` and a `type` (default `rule`). |
+| `get_annotations` | Reads notes as `[number, nodeName, type, text]` rows (text capped at 120 characters). `full: true` returns complete objects; `nodeId` limits to a subtree; `pageId` picks another page. |
+| `update_annotation` | Changes the text or type of one note, by `id` or by reference such as `Sign in #3`. |
+| `delete_annotations` | Deletes notes by ids or references such as `Sign in #3`. |
+
+For `annotate` and `update_annotation`, the first line of `text` is the label and the rest is the body. There are no positions, icons or colours: PaperCraft places each note beside its target, outside the frame, stacked so none overlap. `annotate` is all or nothing: if one note is refused (an unknown layer, or a type the template disables), none is added and the error lists the allowed keys.
+
+Batched call, on a page whose template is Product spec:
+
+```json
+{
+  "notes": [
+    {"node": "Sign in", "type": "rule", "text": "Lock after 5 failed tries\nLocks for 15 minutes, then resets."},
+    {"node": "Email field", "type": "data", "text": "Source: users.email\nValidated on blur"},
+    {"node": "Submit", "type": "behaviour", "text": "Disabled until both fields are valid\nSpinner while the request runs"}
+  ]
+}
+```
+
+The reply is one row per note, `[number, node, type, label]`. Then `get_annotations {}` reads them back, and `delete_annotations {"ids":["Sign in #3"]}` removes one by its frame reference.
+
+**Handoff.** `get_design_spec` and the code exports (`get_jsx`) include the notes of the frame as comments. Each note is one line, `// 1 Business rule: Lock after 5 failed tries`, with its body lines as more `//` lines, so code generated from a frame carries the rules next to the markup.
+
+## Storage
+
+* The page file has an `annotations` list. Each note holds its target (or a point, when it has none), its anchor, label, body, category, position, author (`user` or `agent`) and creation time. A note whose target is gone is marked `detached`.
+* `design.json` holds the categories and the templates, with the project default. A page may name its own template.
+* Old projects load unchanged. A page without annotations saves byte-identical to before.
@@ -0,0 +1,135 @@
+# Chat mode
+
+Chat mode puts a conversation with an agent next to the canvas. Press ⌘J, or use the `Design | Chat` switch in the top bar, to turn it on. The chat column sits on the left (420 to 640 px, 480 by default, resizable) and the live canvas fills the rest. The layers and inspector are hidden; the inspector can be opened as a narrow overlay on the canvas's right edge. Design mode works as before, and a chat keeps running in the background when you switch back.
+
+The mode is remembered per project. Entering a project that was last left in Chat mode opens in Chat mode and shows its newest chat.
+
+Chat mode is native only. The web build shows the switch disabled with a note.
+
+## Backends
+
+Chat drives the same tools as an agent connected over MCP, so the edits, runs, undo and revert behave the same whichever backend you use. There are three ways in: two CLIs that PaperCraft talks to directly, any agent that speaks ACP, and API endpoints.
+
+**Claude Code** runs `claude -p` with streaming JSON in and out. PaperCraft writes an MCP config that points the CLI at the app's own server on `127.0.0.1`, allows the `mcp__papercraft__*` tools, and passes `--strict-mcp-config`, so the CLI sees only PaperCraft's server. The PaperCraft skill text goes in through `--append-system-prompt-file`. The working directory is the project folder. Follow-up messages resume the CLI session by its id, so the agent keeps its context.
+
+**Codex** runs `codex exec --json` in the project folder. The PaperCraft server is added with a `-c mcp_servers.papercraft.url=...` override, and its tools are pre-approved (`default_tools_approval_mode="approve"`), so Codex does not stop to ask for each one. The PaperCraft instructions are prepended to the first prompt of a chat; resumed sessions do not repeat them. Follow-ups resume the Codex session the same way.
+
+**ACP agents** run any agent that speaks the Agent Client Protocol (https://agentclientprotocol.com) over stdio. PaperCraft starts the agent once per turn, sends `initialize` and `session/new` with the project folder as the working directory, and passes PaperCraft's MCP server: over HTTP when the agent supports it, otherwise through the bundled `papercraft-mcp` stdio bridge. The prompt goes out as `session/prompt`, and the agent's streamed updates become the same thread as the other backends: text, thinking, tool cards and the plan. Stop sends `session/cancel`. Follow-ups resume with `session/load` when the agent supports it. ACP has no system prompt field, so the PaperCraft instructions go in front of the first prompt.
+
+The ACP agents PaperCraft knows about, and what was checked on the development Mac:
+
+* **OpenCode** (`opencode acp`): works.
+* **Gemini CLI** (`gemini --acp`): found and started, but its server currently refuses ACP clients, so turns fail with the agent's error until Google changes that.
+* **Cursor** (`cursor-agent acp`): sign in first with `cursor-agent login`.
+* **Pi** (`pi-acp`, an adapter run through `npx`): enable it once in the agent panel or Settings, then it works like the others.
+* **Goose, Kimi, Devin, Junie, Mistral Vibe, Hermes, OpenHands, Stakpak, VT Code, Poolside, Droid**: started with the command their own docs give. They are not all verified here.
+* **Claude Code and Codex ACP adapters** (`npx`): listed under Enable via npx. Claude Code and Codex themselves use the direct backends above.
+
+Agents that run through `npx` are off until you enable them, because enabling runs code that npx fetches from npm.
+
+ACP permissions: PaperCraft's own tools run without asking, except the destructive ones listed under Approval below. Any other tool the agent asks to run (its own shell or file tools, for example) shows an approval card with Approve or Deny in the thread, and Deny is sent back to the agent.
+
+**Custom agents** are your own ACP agents: a name, a command (a program name on the resolved `PATH`, or a full path) and arguments. The arguments are split on spaces, with no quoting. Custom agents appear under Custom in the agent panel and in Settings → Chat.
+
+**API endpoints** call a model over HTTPS with your own key. Settings → Chat holds a list of endpoints, each with a name, a format, a base URL, a model and an optional key. The app's tool list is sent as the API tools, and every tool call runs through the same code path as an MCP call on the UI thread. The loop continues until the model ends its turn, for up to 40 tool rounds per message.
+
+* **Format**: `Anthropic` is the Messages API (`POST {base}/v1/messages`, `x-api-key`). `OpenAI` is Chat Completions (`POST {base}/chat/completions`, `Authorization: Bearer`, streaming `choices[].delta`, tools as `{"type":"function",...}`, tool results as `tool` messages). Both give the same thread: text, tool cards, approvals, Stop, the usage line.
+* **Base URL and model** are free text, for example `https://api.anthropic.com`, any Anthropic-compatible URL, or `http://127.0.0.1:11434/v1`. The key is optional, so local servers need none.
+* A default endpoint named `Anthropic` (`https://api.anthropic.com`, `claude-opus-5-5`) exists from the start, so the first run needs only a key.
+* The agent panel lists Detected agents, API endpoints and Custom agents (see Setup). Each chat remembers its backend.
+* **Claude-only fields** (effort, the thinking summary, the refusal fallback and its beta header, eager tool-input streaming, prompt-cache breakpoints) are sent only when the base URL host is `api.anthropic.com`. For that host the model menu offers `claude-opus-5-5`, `claude-sonnet-5-5` and `claude-haiku-5-5`, effort is `medium` by default (`low` and `high` in the menu), and the Thinking row shows the summary. Every other endpoint gets a plain request. Missing `usage`, thinking or cache fields in the reply are fine.
+* **OpenAI format and images**: attached images are sent as `image_url` data URIs. A tool message in this format carries text only, so a tool result with an image (such as `get_screenshot`) goes back as the text `[image omitted]`, and the image follows as an extra user message in the same round.
+* **Usage line**: input, output and cached tokens, as the server reports them; nothing when it reports none. A cost estimate shows only for the Claude models in the small price table in `src/chat/endpoint.rs`. It is not a bill.
+* `ANTHROPIC_API_KEY` in the environment is used for `api.anthropic.com` when no key is stored. `PAPERCRAFT_ANTHROPIC_BASE_URL` points Anthropic-format requests at another URL (for tests and proxies).
+
+## Setup
+
+### Finding agents
+
+Chat finds agents the way your terminal does. At startup PaperCraft reads your login shell's `PATH` once, off the UI thread (`$SHELL -l`, 3 s limit), and merges it with the app's own `PATH` and the usual folders (`~/.local/bin`, `/opt/homebrew/bin`, `/usr/local/bin`, `~/.cargo/bin`, `~/.bun/bin`, `~/.npm-global/bin`, Volta and nvm). Detection and the agent processes both use that merged `PATH`. This is why an agent installed under `~/.local/bin` or Homebrew is found even when PaperCraft was opened from the Dock.
+
+A row shows a version when the agent reports one. A program with the right name that is not the agent (for example the `goose` database migration tool, which shares its name with Block's Goose agent) shows `Wrong program` with its path, not a false Ready.
+
+PaperCraft never shows install commands. An agent that is not found shows `Not found`, with `Set path…` (opens Settings) and `Docs` (the agent's own documentation). Install the agent with its own installer, then press Detect again.
+
+### Agent panel
+
+Click the agent chip in the chat header. The panel opens over the chat column with a shadow and a dimmed backdrop, sized like the column. It has a search field (name or id), and these sections:
+
+* **Detected**: agents found on your `PATH`, with the version and path. Click one to use it for this chat.
+* **Enable via npx**: agents that start through `npx` (Pi, Qwen Code, Kilo, Cline, Auggie, Copilot CLI, Qoder, CodeBuddy and the Claude Code and Codex ACP adapters). Each row has an `Enable` chip. The section says that it runs code fetched by npx.
+* **Not found**: registry agents that are not on this computer, folded by default.
+* **API endpoints**: your endpoints, with an `Add` action that opens Settings.
+* **Custom**: `Add custom agent` opens Settings.
+
+Each row has a status chip: `Ready`, `Enable`, `Not found`, `Wrong program`, `No key` (an endpoint without a key) or `Set up` (an endpoint without a URL or model). Arrow keys move through the rows, Enter picks one, Escape closes the panel.
+
+Settings → Chat has the same list, so an agent can also be hidden from the panel there (the `Show in the chat agent picker` switch on its row).
+
+### Setup card
+
+A chat with no backend chosen shows one card, "Connect an agent". It lists the agents detected on this computer, up to four, with `Show all agents` for the rest. Below them are `Add an API endpoint` and `Add custom agent`. The card never lists install steps.
+
+### Sign-in
+
+When an agent says it needs you to sign in (ACP's "Authentication required" and similar messages), the failed turn shows "<Agent> needs you to sign in" with the command from the agent's docs, then Retry. For Cursor that is `cursor-agent login`, for OpenCode `opencode auth login`, for Codex `codex login`, for Claude Code's ACP adapter `claude /login`. For agents without a known command the card says to sign in with the agent's own app and retry. Chat does not sign in for you.
+
+### Settings → Chat
+
+The page scrolls and keeps one grid for its labels. Its sections:
+
+* **Agents**: one row per agent, with its status, version and path. A details disclosure holds the **Path override** (for a binary that is not on `PATH`, or a specific install; empty means the first match on the merged `PATH`), the **Arguments override** (replaces the registry's ACP arguments, for example `--acp --debug`), and for npx agents the **Enable** button. The **Show in the chat agent picker** switch hides an agent from the panel. Custom agents have Name, Command and Arguments fields and a Remove button. `Detect again` re-runs detection.
+* **API endpoints**: add, edit and remove endpoints (name, format, base URL, model) and set the default one. Each has a key field with Save and Remove. Keys are stored in the macOS Keychain, Windows Credential Manager or the Linux Secret Service, under the service name `PaperCraft` and the user `api-key:<base URL>`. An older single key (`anthropic-api-key`) is still read for `api.anthropic.com` and moves to the new entry the next time you save it. Removing a key makes that endpoint stop until a key is saved again (for `api.anthropic.com`; other endpoints work without one).
+* **Defaults for new chats**: the backend, the endpoint, and the effort for `api.anthropic.com`.
+
+Settings from before endpoints existed (`api_model`) move into the default endpoint on first load. The `claude_path` and `codex_path` settings from earlier versions still win for their agent until you save the Agents list. These defaults, the agent settings and the endpoint list (never the keys) are saved in `chat_settings.json` in your config folder (`~/Library/Application Support/papercraft/` on macOS). They are not part of any project.
+
+## The thread
+
+The header has the chat title (rename), the chat list (new chat, switch, delete), the agent chip (for example `Claude Code · Opus 5.5`) and the context meter. The meter shows the tokens in the context at the last model call against a 200k window, and turns amber past 75%. It is hidden for Codex, which reports no per-call usage.
+
+Replies are markdown: paragraphs, lists, code blocks with a copy button, inline code and links. While a turn runs, the reply streams in.
+
+* **Thinking**: when the backend reports reasoning, a row shows "Thinking…" while it runs and collapses to a summary when it ends. Expand it to read the text.
+* **Tool cards**: one card per tool call with the verb and target (for example "Drawing layout · Card"), a spinner while it runs, and a failed state with the error. Args and result are collapsible. `get_screenshot` results show a thumbnail.
+* **Step groups**: consecutive tool calls in one reply fold into one line ("Built the card · 5 steps") that expands to the cards.
+* **Plan**: when the agent keeps a todo list (Claude Code's `TodoWrite`, or an ACP plan), the latest list is pinned above the composer with a "done of total" count.
+* **Approval**: on the API backend and for ACP agents, the destructive tools (`delete_pages`, `disable_library`, `import_design_system`, and `delete_nodes` on more than 20 layers) wait for Approve or Deny before they run. Deny returns an error to the model, which can then carry on. For ACP agents, any non-PaperCraft tool the agent asks for shows the same card. The Claude Code and Codex CLIs do not show this card. They use the CLI's own permission rules, and in non-interactive mode a tool that needs permission is denied. The papercraft tools are pre-allowed on both CLIs.
+* **Checkpoint**: when an agent run starts, the thread shows "Checkpoint · before run N". "Restore to here" reverts that run and every run after it, through the same revert as the Agent view.
+* **Run card**: when a run ends, "Agent finished, N changes" with Review, Revert and Accept. These are the same actions as the run review on the canvas.
+* **Errors**: a failed turn shows a red row with Retry. A sign-in problem shows the sign-in card (see Setup).
+* **Canvas follow**: when a tool call targets a node, the canvas pans to it, unless you moved the camera in the last 10 seconds.
+
+## Composer and attachments
+
+Type in the composer, ⏎ sends and ⇧⏎ adds a line. The empty state offers suggestions built from the project, such as "Design a sign-in screen using this project's variables" or "Lint this page and fix warnings".
+
+* **Selection**: the `@ Selection` chip adds the current selection to the message as a chip (also ⌘L). Each click adds another chip, labelled with the layer name or `<first> · N layers`; an identical selection is added once, and each chip is removed on its own. Every chip is sent as a short line with the layer name and node ids.
+* **Start failures**: if a turn cannot start (agent missing, bad path), an error row with Retry shows in the thread and your text stays in the composer.
+* **Images**: the image button opens a file picker. You can also paste a clipboard image or drop image files on the column (PNG, JPEG, GIF, WebP).
+
+For the API backend, images are sent as image blocks, so the model sees them. For the CLIs and ACP agents, each image is saved under `.papercraft-chat-tmp/` in the project and its path is added to the prompt for the agent to read.
+
+While a turn runs, the send button becomes **Stop**. Stop asks the backend to interrupt: the CLIs get an interrupt, or SIGINT, then a kill after 3 seconds; ACP agents get `session/cancel`, then a kill if they do not exit. Every backend ends within 3 seconds. Tools that already ran stay applied, and the partial run can be reviewed or reverted like any other.
+
+## Storage
+
+A chat is one file in the project: `chats/<id>.json`, holding the title, the backend (kind, model, effort, CLI or ACP session id, agent) and the messages with their tool calls, usage and run ids. The API backend also keeps `chats/<id>.api.json`, the raw messages array (Messages format with thinking blocks, or Chat Completions format, whichever the endpoint speaks), so a follow-up replays exactly. The chat records its endpoint id. Deleting a chat asks first and removes both files, and its saved images.
+
+Projects without a `chats/` folder load unchanged. The newest chat opens when you enter Chat mode.
+
+## Privacy
+
+PaperCraft never writes an API key into a project file, a chat or a log. The key lives in the OS credential store. The CLIs and ACP agents run with your own logins and do not get the API keys from the environment: `ANTHROPIC_API_KEY`, `ANTHROPIC_AUTH_TOKEN`, `OPENAI_API_KEY` and `CODEX_API_KEY` are removed from their environment, so Claude Code and Codex bill your account, not a key you set for PaperCraft. The MCP server listens on loopback only, as it does for any other client.
+
+Prompts, project content and tool results go to whichever backend you chose: the CLI's or agent's model service, or the base URL of the endpoint you picked. Nothing goes to any other service. An npx agent downloads its package from npm the first time it runs. If a server echoes your key in an error message, the app hides it before showing the message.
+
+## Limits
+
+* One turn per project at a time. Sending while a turn runs is refused with "A turn is already running"; use Stop first. Switching to another project stops a running turn.
+* The web build has no Chat mode.
+* The canvas shows the run's outlines after the turn ends, when the run is reviewed. They are not drawn live while the agent works.
+* The API backend stops after 40 tool rounds in one message and says so.
+* Codex reports no per-call usage, so the context meter is hidden for it.
+* Agents need to be installed and signed in with their own tools. Chat does not install them or sign them in for you.
+* ACP terminal and file-system requests from an agent are answered as not supported. Agents use their own file tools.
@@ -0,0 +1,71 @@
+# Annotations: notes with leader lines that explain a design
+
+## Why (user request, 2026-10-21)
+
+Teams annotate designs in Figma with callouts and arrows that explain what each part does: business rules, behaviour, states, data sources, edge cases. They are toggled on for review and handoff and off for presenting. PaperCraft has comments (threads, open/resolved) but nothing that documents a design in place.
+
+## Model
+
+* An **annotation** belongs to a page: `{ id, target: NodeId (or a point), anchor: side or offset on the target, label: short title, body: markdown text, category, number, position: where the note sits on the canvas, author: user | agent, created }`. Stored in the page file under `annotations` (serde default; old pages load unchanged).
+* **Categories** are project-level, editable: default `Business rule`, `Behaviour`, `Content`, `Data`, `Accessibility`, `Dev note`, each with a colour (theme palette) and icon.
+* Annotations survive moves and resizes of the target (anchor is relative); deleting the target keeps the annotation detached with a warning badge.
+
+## Classification drives the look (user, 2026-10-21)
+
+* The **category is the only styling input**. Icon, colour, badge shape and default label prefix come from the category; an annotation stores no icon or colour of its own. Changing a category's colour or icon restyles every note in it.
+* Categories carry a short **type key** used everywhere (`rule`, `behaviour`, `content`, `data`, `a11y`, `dev`); custom categories get a key too.
+* **Hiding information**, three levels, all undo-free view state (not saved in the design):
+  * per note: collapse to its number badge only (click the badge to expand);
+  * per category: show/hide from the category filter;
+  * global (⌘⇧A cycles; ⇧A is Add auto layout): full notes → badges only → hidden.
+  * Exports and Present mode use "hidden" unless chosen otherwise.
+
+## Templates (user, 2026-10-21)
+
+People annotate differently per project and even per page (a product spec, a dev handoff, an accessibility review). A **template** says which kinds of notes are wanted and what each should contain.
+
+* `AnnotationTemplate { id, name, categories: [ { key, enabled, prompt: short guidance for what this note should say, fields: [name] (optional structured lines, e.g. "Applies when", "Owner") } ], display: full | badges }`.
+* Stored in `design.json` (project-level list); the **project default** is one template, and a **page can override** it (`page.annotation_template`, serde default). New categories added in a template become available project-wide.
+* **Built-in templates** (editable copies, not locked): `Product spec` (rule, behaviour, content, data), `Dev handoff` (behaviour, data, dev, a11y), `Accessibility review` (a11y with fields "Issue", "WCAG", "Fix"), `Content review` (content with "Tone", "Max length"), `Minimal` (rule only).
+* **UI**: the Annotations side view header has a template picker (project default or this page) and a "Customize…" modal: toggle categories, edit name/colour/icon/key, edit each category's guidance and fields, duplicate/reset a template. The Annotate popover only offers the template's enabled categories, and shows the fields as labelled lines.
+* **Ask AI**: an "Annotate with AI" button in the side view (and a chat suggestion "Annotate this page") sends a prompt to the chat: annotate the selected frame or the page using the active template. The agent reads the template with one cheap call.
+* MCP: `get_annotation_template {pageId?}` returns compact `[[key, guidance, fields]]` for the enabled categories (a few hundred tokens); `annotate` rejects types the page's template disables (error lists the allowed keys) and accepts `fields` as `"Name: value"` lines inside `text`. `set_annotation_template {pageId?, template}` switches it.
+
+## Cheap for agents
+
+* One tool call can add many notes: `annotate {notes: [{node, text, type}]}` where `node` is a node id or a layer name on the active page, `text` is the note (first line becomes the label, the rest the body), `type` is the category key (default `rule`). No positions, icons or colours: placement is automatic (beside the target, outside its frame, stacked without overlap).
+* `get_annotations` returns compact rows `[n, node, type, text]`, not full objects; `{full: true}` for everything.
+* `update_annotation` / `delete_annotations` take ids or numbers ("frame Sign in #3").
+* The tool description stays under ~60 words.
+
+## Canvas
+
+* A note is a small card (number badge, label, first lines of the body) connected to its target by a **leader line**: elbow or straight, ending in a dot or arrow on the target's anchor, plus a thin outline around the target while hovered.
+* Notes are draggable; the line re-routes (reuse the connector router, `src/connector.rs`).
+* **Toggle**: View → Annotations (⌘⇧A) shows or hides all; a filter per category; never drawn in Present mode or exports (notes live only in the editor overlay; an export option to include them is a later item).
+* Numbering is per frame, in reading order, so a frame reads "1, 2, 3…".
+
+## UI
+
+* **Annotate tool** (N; A is the Frame tool): click a layer, type the note; or select layers → right-click → Annotate.
+* **Annotations side view**: list per frame with number, category chip, label; click to select and zoom; filter by category; edit inline.
+* **Inspector**: an Annotations section for the selected layer.
+
+## Agents and handoff
+
+* MCP: `annotate` (batch, see "Cheap for agents"), `get_annotations`, `update_annotation`, `delete_annotations`; classified in `edits_doc`.
+* `get_design_spec` and `get_jsx` include annotations as comments (`// 1 Business rule: …`), so code generated from a frame carries the rules.
+* Chat: the `@ Selection` context includes the selected layers' annotations; the agent can be asked to "annotate this screen".
+
+## Mock-ups
+
+`PaperCraft` design file, page `Annotations`: `Canvas / Annotated frame` (several categories, leader lines, numbering), `Canvas / Annotations hidden`, `Panel / Annotations` (344x1440), `Inspector / Annotation` (344x1440), `Popover / New annotation`.
+
+## Acceptance
+
+* Add, edit, move, hide/show, filter, delete annotations; undo for each.
+* Moving or resizing a target keeps the leader line attached; deleting it detaches the note with a badge.
+* Old projects load unchanged; page files without `annotations` stay byte-identical on save.
+* Exports and Present mode never include annotations.
+* MCP tools round trip; `get_design_spec` includes them.
+* Screenshot check against the mock-ups; tests for model, anchoring, numbering, serialization, MCP.
@@ -0,0 +1,24 @@
+# Tasks
+
+Stop on failure. UI tasks go to Sonnet, never Haiku. Agents clean up after themselves.
+
+## Wave 1 (with chat-agents wave 1)
+
+- [x] 1. **Mock-ups** on page `Annotations`. Sonnet.
+
+## Wave 2 (parallel with chat-agents wave 2)
+
+- [x] 2. **Model and storage**: `Annotation`, categories in `design.json`, page field (serde default, byte-identical save for old pages), anchoring relative to target, numbering per frame in reading order, undoable edits through `Editor`. Tests. Sonnet.
+- [x] 3. **MCP tools** `add_annotation`, `get_annotations`, `update_annotation`, `delete_annotations`; `get_design_spec` / `get_jsx` include them as comments; classified in `edits_doc`. Codex Sol (Sonnet if unavailable).
+
+- [x] 3b. **Templates**: model in `design.json` + page override, built-ins, `get_annotation_template` / `set_annotation_template`, `annotate` validates against the page's template. Sonnet (after 3).
+
+## Wave 3 (after wave 2 and the mock-ups)
+
+- [x] 4. **Canvas**: note cards, leader lines (connector router), drag, toggle ⇧A, category filter, hidden in Present and exports unless asked. Sonnet.
+- [x] 5. **Annotate tool, side view (template picker, Customize modal, Annotate with AI), inspector section, popover**. Sonnet.
+
+## Wave 4
+
+- [x] 6. **Review** (Codex Sol, read-only) and fixes (Sonnet); chat `@ Selection` context includes annotations.
+- [x] 7. **Docs** (Haiku): `docs/annotations.md`, README, `docs/agents.md`, ROADMAP, PROGRESS.
@@ -0,0 +1,38 @@
+# Chat agents: any agent, found reliably, and a picker that scales
+
+## Why (user report, 2026-10-21)
+
+* Claude Code and Codex show "Not found on PATH" although both are installed in `~/.local/bin`. Root cause: an app opened from the Dock or Finder gets the minimal macOS PATH (`/usr/bin:/bin:/usr/sbin:/sbin`); `launchctl getenv PATH` is empty. The user's login shell also finds `pi`, `opencode`, `gemini`, `goose` (`/opt/homebrew/bin`) and `cursor-agent` (`~/.local/bin`).
+* The setup state offers `npm install -g …` as the way to install agents. Claude Code and Codex have their own installers; PaperCraft should not tell people how to install agents at all.
+* Only two agents are supported; the user wants every popular agent, generically.
+* The agent picker popup has no shadow and overlaps the setup card; the Settings → Chat page has broken spacing, padding and height (fields not aligned, the page bottom cut off).
+* Sending a message did nothing: no `chats/` folder was created, no error was shown.
+* The composer allows one `@ Selection` chip; the user wants several.
+
+## Scope
+
+1. **Find agents like the shell does.** At startup (native, off the UI thread), resolve the login shell PATH once: `$SHELL -l -c 'printf %s "$PATH"'` with a 3 s timeout; merge with the process PATH and common folders (`~/.local/bin`, `/opt/homebrew/bin`, `/usr/local/bin`, `~/.cargo/bin`, `~/.bun/bin`, `~/.npm-global/bin`, Volta and nvm current bins). Use it for agent detection and for spawning agents (set `PATH` on the child). A path override in Settings still wins.
+2. **ACP backend** (`src/chat/acp.rs`): a generic Agent Client Protocol client (JSON-RPC 2.0 over the agent's stdio): `initialize`, `session/new` with `cwd` = project folder and `mcpServers` = PaperCraft's server (HTTP entry when the agent advertises `mcpCapabilities.http`, else a stdio entry running the bundled `papercraft-mcp` bridge with `PAPERCRAFT_MCP_PORT`), `session/prompt` with text (and image) content blocks, streaming `session/update` notifications mapped to our `Event`s (agent message chunks → Text, thought chunks → Thinking, tool_call / tool_call_update → ToolStart/ToolEnd, plan → Plan items), `session/cancel` for Stop, `session/request_permission` answered from our approval flow (papercraft tools allowed; destructive ones and any non-papercraft tool ask the user), `session/load` to resume when supported. The PaperCraft skill text goes in as the first prompt's leading context (ACP has no system prompt field).
+3. **Agent registry, as data** (`src/chat/agents.rs`): `{ id, name, detect: binary name, launch: command + args, kind: Native | Npx, docs_url }`. Native entries are found on the resolved PATH: Gemini CLI (`gemini --acp`), Cursor (`cursor-agent acp`), OpenCode (`opencode acp`), Goose (`goose acp`), Kimi (`kimi acp`), Devin (`devin acp`), Junie (`junie --acp=true`), Mistral Vibe (`vibe-acp`), Hermes (`hermes acp`), OpenHands (`openhands acp`), Stakpak (`stakpak acp`), VT Code (`vtcode acp`), Poolside (`pool acp`), Droid (`droid exec --output-format acp-daemon`). `npx`-launched entries (Qwen Code, Kilo, Cline, Auggie, Copilot CLI, Qoder, Codebuddy, Pi via `pi-acp`, Claude/Codex via their ACP adapters) are listed as available but off until the user enables them once, because enabling runs code fetched by `npx`. Claude Code and Codex keep their direct adapters (already proven) and are the default for them. Exact flags are verified against each installed agent's `--help` where installed; the rest keep the documented command and fail with the agent's own error.
+4. **Custom agent**: name + command + args (ACP over stdio). No provider lists beyond the registry.
+5. **No install instructions.** A missing agent shows "Not found" plus "Set path…" and a link to the agent's own docs (`docs_url`), nothing else.
+6. **Agent picker becomes a panel**, not a dropdown: opened from the agent chip, sized like the chat column (overlay with shadow and a backdrop), sections Detected, Enable (npx), API endpoints, Custom, a search field, and per row: icon, name, status chip (Ready, Needs enable, Not found, Signed out if detectable), version, path. Clicking a row selects it for this chat.
+7. **Settings → Chat** redesign with the same list (one row per agent with a details disclosure: path override, args override, enable), API endpoints as compact rows with an edit disclosure, consistent 16/24 px padding, labels aligned on one grid, the page scrolls instead of being cut off.
+8. **Setup state** in the chat column: one card "Connect an agent" listing detected agents to pick from (usually already some), plus "Add an API endpoint" and "Add custom agent"; no install commands.
+9. **Send bug**: reproduce, find the root cause, fix, and add a regression test; any start failure must show an error row in the thread (never a silent no-op) and keep the typed text.
+10. **Multiple selections**: each `@` adds a chip (selection at that moment, labelled by layer names); chips stack, can be removed one by one; all are sent as context lines with node ids.
+
+## Not in scope
+
+* Installing agents.
+* ACP terminal/file-system client methods beyond what PaperCraft needs (answer `fs/*` and `terminal/*` requests with "not supported" unless the agent requires them to work; most agents use their own file tools).
+
+## Acceptance
+
+* With the app launched from the Dock: Claude Code, Codex, Pi, OpenCode, Gemini, Goose and Cursor are detected on this machine.
+* A turn with Gemini CLI, OpenCode, Goose and Cursor (each installed here) creates an artboard through PaperCraft's tools via ACP; a Pi turn works after enabling `pi-acp`.
+* Stop cancels an ACP turn within 3 s.
+* Picker panel, Settings → Chat and the setup state match new mock-ups at 1440p and 1280x800; nothing clipped; shadows on overlays.
+* Sending a message always either starts a turn or shows an error row.
+* Three `@` chips can be added and removed independently.
+* Tests: PATH merge, registry detection with a fake PATH, ACP JSON-RPC handshake and update mapping against a fake agent process (recorded fixture), permission flow, cancel.
@@ -0,0 +1,23 @@
+# Tasks
+
+Stop on failure. UI tasks go to Sonnet (or Codex Sol), never Haiku. Each agent cleans its temp homes, logs and drivers when done; one shared `target/`.
+
+## Wave 1 (parallel)
+
+- [x] 1. **Mock-ups** on page `Chat agents` (agent panel, setup, Settings / Chat, multiple selections). Sonnet.
+- [x] 2. **PATH resolution, no install hints, send bug, multiple `@` chips** (spec items 1, 5, 9, 10). Sonnet.
+
+## Wave 2 (after wave 1)
+
+- [x] 3. **ACP backend** `src/chat/acp.rs`: JSON-RPC client, session/new with PaperCraft's MCP server (HTTP or the `papercraft-mcp` stdio bridge), prompt, update mapping, permission flow, cancel, load. Fake-agent fixture tests; real turns with Gemini CLI, OpenCode, Goose and Cursor (installed here). Sonnet.
+- [x] 4. **Agent registry and custom agents** `src/chat/agents.rs`: data table, detection on the resolved PATH, npx enable state, custom agent entries in ChatPrefs, BackendKind/Backend for ACP agents. Codex Sol (Sonnet if unavailable).
+
+## Wave 3 (after wave 2 and the mock-ups)
+
+- [x] 5. **Agent panel and setup state** in the chat column (spec items 6, 8). Sonnet.
+- [x] 6. **Settings → Chat redesign** (spec item 7). Sonnet.
+
+## Wave 4
+
+- [x] 7. **Review** (Codex Sol, read-only), fixes (Sonnet).
+- [x] 8. **Docs** `docs/chat.md` (agents, ACP, custom), README. Haiku.
@@ -0,0 +1,113 @@
+# Chat layout: design by conversation
+
+## Why
+
+Today an agent drives PaperCraft from outside: a terminal running Claude Code or Codex, pointed at the MCP server. The app shows a working pill, the agent runs and their review, but the conversation itself lives elsewhere. OpenDesign and Cursor's agent view put the conversation next to the result. PaperCraft already has everything behind that: 61 tools, agent runs with auto-versions and review, skills, design systems and libraries.
+
+## Decisions (user, 2026-10-21)
+
+* Backend: **both** local agent CLIs (Claude Code, Codex) and a bring-your-own-key Anthropic API path.
+* Layout: a separate **Chat layout**, chat column left, live canvas right, switched from the top bar (`Design | Chat`).
+* Conversations live **in the project** (`chats/`), linked to the agent runs they produce.
+* Mock-ups first.
+
+## What exists today
+
+* MCP server on `127.0.0.1:<PAPERCRAFT_MCP_PORT>` (default 29980), loopback only, rejects `Origin` headers (`src/mcp/server.rs`). Every tool runs on the UI thread through `App::run_mcp_calls` and `mcp::exec::call`.
+* Agent runs (`src/runs.rs`): editing calls grouped into runs with auto-versions, review, revert, the finish toast.
+* Tool list and schemas: `mcp::server::tool_list()`, `crate::mcp::tools::edits_doc`.
+* Skills: `skills/papercraft`, `skills/papercraft-design`, `skills/papercraft-design-system` (in repo) and the installed copies under `~/.agents/skills/`.
+* No HTTP client for outbound API calls except `reqwest` (already in `Cargo.lock` through rmcp) and `curl` used by the CLI's icon download.
+
+## Layout
+
+* **Mode switch** in the top bar: `Design | Chat` (segmented control), shortcut ⌘J. The mode is per window and remembered per project.
+* **Chat mode**: left column 420–640 px wide (resizable, default 480), canvas on the right with the normal top bar, zoom and a slim tool strip; the layers, inspector and side views are hidden (a toggle brings the inspector back as a narrow overlay).
+* **Chat column**, top to bottom:
+  * header: chat title (rename), chat list menu (new chat, switch, delete with confirm), agent picker chip (`Claude Code · Opus 5.5`, `Codex · gpt-6.1-sol`, `API · Opus 5.5`) and a settings icon;
+  * message list: user messages; assistant text streamed as it arrives (markdown: paragraphs, lists, code, inline code, links); thinking/progress shown as a collapsed one-line "Thinking…" row when the backend provides it; **tool-call cards**: verb + target ("Drawing layout · Card", from `agent_verb`), status (running spinner, done, failed with the error), collapsible args/result JSON, a thumbnail for `get_screenshot` results; a **run card** when an agent run ends (`Agent finished, N changes` with Review, Revert, Accept, reusing the run review); errors as a red row with Retry;
+  * composer: multi-line input (⏎ sends, ⇧⏎ newline), attachment chips (current selection as `@Frame name` chips added by a button or ⌘L, images by paste/drag, the active page), a Stop button while a turn runs, a model/effort menu for the API backend;
+  * empty state: suggestions built from the project ("Design a sign-in screen using this project's variables", "Lint this page and fix warnings", "Make a dark mode").
+* **Patterns from shadcn AI Elements** (ui.shadcn.com/docs/ai-elements; React components, so only their patterns and names are reused, built from `src/ui/kit.rs`):
+  * **Chat** thread with a message scroller that sticks to the bottom while streaming and keeps your place when you scroll up (a "Jump to latest" pill appears).
+  * **Message**: user and assistant turns; assistant actions on hover (copy, retry).
+  * **Reasoning**: collapsible, streams while open, collapses to "Thought for 12s" when done.
+  * **Tool**: one card per call, states pending / running / done / error, input and output sections collapsible; a screenshot output shows inline.
+  * **Task / Chain of Thought**: consecutive tool calls in one assistant turn group into a step list ("Built the card · 5 steps") that expands.
+  * **Plan / Queue**: when the agent keeps a todo list (Claude Code `TodoWrite`, or the API backend's plan), show remaining and completed items pinned above the composer.
+  * **Confirmation**: approve or deny before destructive tools run (`delete_pages`, `delete_nodes` on more than 20 layers, `disable_library`, `import_design_system`); API backend pauses the loop; CLI backends rely on the CLI's own permission prompt where it exists, else the tool stays allowed and the run can be reverted.
+  * **Checkpoint**: each agent run's auto-version shows as a checkpoint in the thread; "Restore to here" reverts the runs after it (reuses `runs::revert`).
+  * **Context**: a small meter in the header with tokens used of the model's context window (API and Claude Code report usage).
+  * **Model Selector**: backend + model menu and an effort menu.
+  * **Prompt Input**: multi-line field, attachments (selection, images, page), send / stop.
+  * **Suggestion**: one-click prompts in the empty state and after a run ("Lint this", "Make a dark mode", "Review changes").
+  * **Subagent**: a nested, collapsible block when a CLI agent spawns a sub-agent.
+  * **Code Block**: fenced code in replies with a copy button.
+  * Not used: Sources, Inline Citation, File Tree, Terminal, Stack Trace, Test Results (not design work).
+* **Canvas side**: follows the agent: when a tool call targets a node, the canvas pans to it unless the user moved the camera in the last 10 s; the run overlay (green/yellow/red outlines) shows while a run is open.
+* Design mode keeps working as today; the chat keeps running in the background when you switch.
+
+## Backends
+
+All backends drive the same tools, so runs, undo, review and revert work the same.
+
+### Local agent CLIs
+
+* **Claude Code**: spawn `claude -p` with streaming JSON in and out (`--input-format stream-json --output-format stream-json --verbose`), an MCP config pointing at the app's server (`--mcp-config` with `{"mcpServers":{"papercraft":{"type":"http","url":"http://127.0.0.1:<port>/mcp"}}}`), the papercraft tools allowed (`--allowedTools "mcp__papercraft__*"`), working directory = the project folder, and the system prompt appended with the PaperCraft skill text. Resume with `--resume <session_id>` (stored on the chat). Exact flags are checked against `claude --help` at implementation time and wrapped in one adapter.
+* **Codex**: spawn `codex exec --json` with the server added through `-c mcp_servers.papercraft.url=...` (or the current equivalent, checked against `codex exec --help`), resume with its session id. Same adapter shape.
+* **Detection**: Settings → Chat lists the CLIs found on `PATH` (plus a path override) with their version; a missing CLI shows install hints, never an error dialog.
+* **Events**: each adapter turns the CLI's JSON lines into one internal event stream: `Text(delta)`, `Thinking(delta)`, `ToolStart{id,name,args}`, `ToolEnd{id,result|error}`, `TurnEnd{usage?}`, `Error`. Tool calls also arrive through the MCP server, so the card status is confirmed by the app itself (`log_agent`), not only by the CLI's report.
+* **Stop**: sends an interrupt (stdin control message where supported, else SIGINT, then kill after 3 s). The run so far stays reviewable.
+* **Security**: the CLI runs with the user's own permissions and logins; PaperCraft passes no keys. Only papercraft tools are pre-allowed; other tools follow the CLI's own permission settings (non-interactive: denied).
+
+### Anthropic API (bring your own key)
+
+* Raw HTTPS to `POST https://api.anthropic.com/v1/messages` with `stream: true` (no Rust SDK exists), using `reqwest` (already a dependency).
+* **Key**: entered in Settings → Chat, stored in the macOS Keychain (Linux: Secret Service; Windows: Credential Manager) through the `keyring` crate, never in project files or logs. `ANTHROPIC_API_KEY` in the environment is used when no key is stored.
+* **Model**: default `claude-opus-5-5`; menu also offers `claude-sonnet-5-5` and `claude-haiku-5-5`. Thinking adaptive (default on these models), `output_config.effort` set explicitly (default `medium`, menu low/medium/high), `thinking.display: "summarized"` so the Thinking row has text. Server-side refusal fallback on (`fallbacks: "default"` with beta `server-side-fallback-2026-07-01`; for Haiku, show the refusal instead).
+* **Tools**: the app's own tool list (`tool_list()` converted to Messages API `tools`: name, description, input_schema), with `eager_input_streaming: true`; inputs are parsed tolerantly, validated against the schema before running, and run through `mcp::exec::call` on the UI thread like any MCP call (so runs and undo behave the same). Several `tool_use` blocks in one turn run in order and all `tool_result` blocks go back in one user message; failures go back as `is_error: true`. No forced `tool_choice` (not supported on these models).
+* **Loop**: stream → collect `tool_use` → run → append `response.content` unchanged (thinking blocks included) + tool results → next request, until `stop_reason` is `end_turn`; `max_tokens` → continue once with a note; `refusal` → show the category; `pause_turn` → continue. Max 40 tool rounds per user message (then stop and say so).
+* **Caching**: `cache_control` breakpoints on the tool list and on the system prompt (skill text + project context), stable ordering so they hit; per-turn volatile context (selection, active page) goes in the user message, not the system prompt. `usage.cache_read_input_tokens` is logged to verify.
+* **Images**: `get_screenshot` results go back as image blocks so the model sees what it made; user-attached images too.
+* **Cost line**: per turn input/output/cache tokens and an estimated cost from a small price table, shown under the turn in a muted row.
+* Implementers read the bundled claude-api skill files `curl/examples.md`, `shared/tool-use-concepts.md`, `shared/prompt-caching.md`, `shared/model-migration.md` (Opus 5.5 section) before writing this adapter.
+
+### Custom endpoints (generic, no provider list)
+
+The API backend is not tied to Anthropic. Settings → Chat holds one or more **endpoints**, each `{ name, format, base_url, model, key }`:
+
+* `format`: `anthropic` (Messages API, `POST {base}/v1/messages`, `x-api-key`) or `openai` (Chat Completions, `POST {base}/chat/completions`, `Authorization: Bearer`, streaming SSE `choices[].delta`, tools as `{"type":"function","function":{name,description,parameters}}`, `tool_calls` with `arguments` streamed as string fragments, results as `role: "tool"` messages).
+* `base_url`: free text (e.g. `https://api.anthropic.com`, any Anthropic-compatible URL, `http://127.0.0.1:11434/v1`). `model`: free text. `key`: optional (local servers need none), stored in the OS keychain under the endpoint's base URL, never in settings files.
+* Claude-only request fields (`output_config.effort`, `thinking.display`, `fallbacks` and its beta header, `eager_input_streaming`) are sent only when the base URL host is `api.anthropic.com`; other Anthropic-format endpoints get a plain request (adaptive thinking omitted), and are tolerant of missing `usage`, `thinking` blocks, or `cache_*` fields.
+* The cost line shows a price only for models in the built-in Claude price table; otherwise tokens only (or nothing when the server reports no usage).
+* No provider names, presets or logos in the app. A default endpoint `Anthropic` (`anthropic`, `https://api.anthropic.com`, `claude-opus-5-5`) exists so the first-run path stays one key away.
+* The agent picker lists every configured endpoint by its name.
+
+### Not in scope (v1)
+
+* Named provider presets.
+* Multiple chats running at once in one project (one active turn per project).
+* Voice, file uploads other than images.
+
+## Storage
+
+* `chats/<id>.json` in the project folder: `{ id, title, created, updated, backend: {kind, model?, effort?, cli_session?}, messages: [ {role, text, tools:[{id,name,args,result,error,ms}], run_id?, usage?, at} ] }`. API backend also keeps the raw `messages` array (for exact replay, including thinking blocks) in `chats/<id>.api.json`.
+* Chats sync with the project (relay). Deleting a chat deletes both files after a confirm.
+* The project's newest chat opens when entering Chat mode.
+
+## MCP and CLI
+
+* No new tools needed. `papercraft-cli` is unchanged.
+
+## Acceptance
+
+* Chat mode toggles from the top bar and ⌘J; layout matches the mock-ups at 1440p and 1280x800.
+* With Claude Code installed: "Create a 390x844 artboard named Test with a centred title" streams text, shows tool cards for `create_artboard` and `write_html`, the canvas follows, a run card appears at the end, Review/Revert work; a follow-up message continues the same CLI session.
+* Same with Codex.
+* With an API key: the same prompt works through the API backend; thinking row shows a summary; cost line shows tokens; a second turn reads from cache (`cache_read_input_tokens > 0`).
+* Stop during a long turn ends it within 3 s; tools already applied stay and are revertible.
+* Missing CLI and missing key show setup states, not errors; a bad key shows the API error message.
+* Chats persist in `chats/` and reopen after restart; a project without `chats/` loads unchanged.
+* The key never appears in project files, logs or crash output (test greps the project folder and the log after a run).
+* Tests: event parsing for each adapter from recorded JSON fixtures (Claude Code stream-json, Codex --json, Anthropic SSE incl. thinking, tool_use with input_json_delta, refusal, max_tokens); tool-schema conversion; chat file round trip; the API loop with a fake HTTP server (two tool rounds then end_turn).
+* `cargo test --no-fail-fast`, wasm and Windows checks pass (chat backends are native-only; the web build shows Chat mode disabled with a note).
@@ -0,0 +1,33 @@
+# Tasks
+
+Stop on failure. Tasks in one wave touch different files and run in parallel; a wave starts when the previous one passes `cargo test --lib`. A read-only review after waves 2 and 4; real findings are fixed before moving on.
+
+## Wave 0: design (parallel with wave 1)
+
+- [x] 0. **Mock-ups** in the `PaperCraft` design file, new page `Chat`: `Chat / Empty`, `Chat / Streaming` (text + tool cards + thinking row), `Chat / Run finished` (run card, canvas overlay), `Chat / Agent picker` (menu open, CLIs found/missing, API), `Chat / Setup` (no CLI, no key), `Settings / Chat`, at 2560x1440 and a 1280x800 variant of `Chat / Streaming`. The user's app had another project open, so this ran through the 0.5.0 offline CLI on the `PaperCraft` project (each call refuses if the app has it open); never `open_file` in the user's app.
+
+## Wave 1: model and storage (parallel)
+
+- [x] 1. **Chat model and storage** (new `src/chat/mod.rs`, `src/chat/store.rs`): types from the spec, `chats/` load/save/list/delete, legacy project without `chats/`. Tests: round trip, listing order, delete.
+- [x] 2. **Event stream and adapters' parsing** (new `src/chat/events.rs`, `src/chat/claude_code.rs`, `src/chat/codex.rs`, `src/chat/anthropic.rs` parsing half): the internal `Event` enum and pure parsers from recorded fixtures (`tests/fixtures/chat/`). Record real fixtures by running the CLIs once on a scratch project with a throwaway prompt (no user data); for the API, build SSE fixtures from the documented event shapes. Tests per backend.
+
+## Wave 2: backends (after wave 1; 3, 4, 5 parallel)
+
+- [x] 3. **Claude Code process** (`src/chat/claude_code.rs`): detect, spawn with MCP config and allowed tools, stream stdin/stdout on a worker thread, resume, stop. Integration test gated on `claude` being on PATH (skipped otherwise).
+- [x] 4. **Codex process** (`src/chat/codex.rs`): same for `codex exec --json`. Gated test.
+- [x] 5. **Anthropic API loop** (`src/chat/anthropic.rs`, `keyring` dependency): key storage, request building (tools from `tool_list()`, caching, effort, thinking display, fallbacks), SSE streaming, tool loop through a channel to the UI thread (`mcp::exec::call`), usage and cost. Test with a fake HTTP server.
+
+## Wave 3: UI (after wave 2 and the mock-ups; 6 then 7 and 8 parallel)
+
+- [x] 6. **Chat layout and mode switch** (`src/ui/chat.rs`, `src/ui/mod.rs`): Design | Chat toggle, ⌘J, column + canvas layout, resizable column, remembered per project.
+- [x] 7. **Messages and composer** (`src/ui/chat.rs`): markdown text, thinking row, tool cards, run card (reuse run review actions), errors with Retry, composer with attachments, Stop, empty state suggestions, agent picker, chat list. Canvas follows tool targets.
+- [x] 8. **Settings → Chat** (`src/ui/settings.rs`): CLI detection and paths, API key (Keychain), default backend/model/effort.
+
+## Wave 4: finish
+
+- [x] 9. **End-to-end check** with each available backend on a scratch copy of a project (own app instance on its own port and `PAPERCRAFT_HOME`), screenshots against the mock-ups, key-leak grep.
+- [x] 10. **Docs and release notes**: `docs/chat.md`, README section and screenshot, `docs/agents.md`, ROADMAP row 44 done, PROGRESS entry; full test suite, wasm and Windows checks.
+
+## Model per task
+
+Claude Sonnet: 0, 2, 3, 5, 6, 7, 9. Claude Haiku: 1, 8, 10. Codex `gpt-6.1-sol`: 4 and the reviews (Claude Sonnet if Codex is unavailable).
@@ -51,6 +51,7 @@ pub struct App {
    mcp: Option<(
        std::sync::mpsc::Receiver<crate::mcp::Call>,
        crate::mcp::server::Running,
+        crate::mcp::server::Dispatch,
    )>,
    /// Groups the agent's editing calls into reviewable runs.
    runs: crate::runs::Tracker,
@@ -715,7 +716,12 @@ impl App {
            dir.map(|p| p.dir.as_path()),
            &self.ed,
        );
+        if self.st.chat.take_finish_run() {
+            // A chat turn that edited is over: close its run now, not after the 30 s idle timeout.
+            self.runs.finish(crate::project::format::now_ms(), &self.ed);
+        }
        self.st.sync_runs(&mut self.runs);
+        self.st.chat.tools = self.tool_dispatch().map(crate::chat::events::ToolDispatch);
        let Some(g) = self.gfx.as_mut() else { return };
        let input = g.egui.take_egui_input(&g.window);
        let mut l = frame::layout(&self.ctx, input, &mut self.ed, &mut self.st);
@@ -1436,10 +1442,16 @@ fn physical_char(c: winit::keyboard::KeyCode) -> Option<char> {
 }

 impl App {
+    /// Sends a tool call to the UI thread like an MCP request (runs, undo and the agent log
+    /// behave the same); for the chat's API backend (`TurnConfig::tools`).
+    pub fn tool_dispatch(&self) -> Option<crate::mcp::server::Dispatch> {
+        self.mcp.as_ref().map(|(_, _, d)| d.clone())
+    }
+
    /// Run the MCP tool calls that arrived since the last wake-up, then repaint.
    fn run_mcp_calls(&mut self) {
        let calls: Vec<crate::mcp::Call> = match &self.mcp {
-            Some((rx, _)) => rx.try_iter().collect(),
+            Some((rx, _, _)) => rx.try_iter().collect(),
            None => return,
        };
        if calls.is_empty() {
@@ -1517,6 +1529,7 @@ fn start_mcp(
 ) -> Option<(
    std::sync::mpsc::Receiver<crate::mcp::Call>,
    crate::mcp::server::Running,
+    crate::mcp::server::Dispatch,
 )> {
    if std::env::var("PAPERCRAFT_MCP").is_ok_and(|v| matches!(v.as_str(), "0" | "off" | "false")) {
        return None;
@@ -1526,10 +1539,10 @@ fn start_mcp(
    let dispatch: crate::mcp::server::Dispatch = std::sync::Arc::new(move |call| {
        tx.lock().unwrap().send(call).is_ok() && proxy.send_event(UserEvent::Mcp).is_ok()
    });
-    match crate::mcp::server::spawn(crate::mcp::port(), dispatch) {
+    match crate::mcp::server::spawn(crate::mcp::port(), dispatch.clone()) {
        Ok(running) => {
            log::info!("MCP server listening on {}", running.url());
-            Some((rx, running))
+            Some((rx, running, dispatch))
        }
        Err(e) => {
            log::warn!("MCP server not started: {e}");
@@ -1545,6 +1558,8 @@ fn prefer_x11(kernel_release: &str, display: Option<&std::ffi::OsStr>) -> bool {
 }

 pub fn run(start: Start) -> Result<(), String> {
+    #[cfg(not(target_arch = "wasm32"))]
+    crate::chat::path::init();
    let store = Store::open(Store::default_root())
        .map_err(|e| format!("cannot create the projects folder: {e}"))?;
    let mut builder = EventLoop::<UserEvent>::with_user_event();
@@ -1570,7 +1585,7 @@ pub fn run(start: Start) -> Result<(), String> {
    }
    let mut app = App::new(start, store);
    app.mcp = start_mcp(event_loop.create_proxy());
-    app.st.agent_endpoint = app.mcp.as_ref().map(|(_, r)| r.url()).unwrap_or_default();
+    app.st.agent_endpoint = app.mcp.as_ref().map(|(_, r, _)| r.url()).unwrap_or_default();
    event_loop.run_app(&mut app).map_err(|e| e.to_string())
 }

@@ -0,0 +1,791 @@
+//! A generic Agent Client Protocol client (https://agentclientprotocol.com): JSON-RPC 2.0, one
+//! message per line, over the agent's stdio. One process per turn: `initialize`, `session/new`
+//! (or `session/load`) with PaperCraft's MCP server, `session/prompt`, then the agent's
+//! `session/update` notifications are mapped to [`Event`]s until the prompt response arrives.
+
+use super::events::{Event, Turn, TurnConfig};
+use super::{tools, Usage};
+use base64::{engine::general_purpose::STANDARD, Engine};
+use serde_json::{json, Value};
+use std::collections::HashMap;
+use std::io::{BufRead, BufReader, Read, Write};
+use std::path::{Path, PathBuf};
+use std::process::{Child, ChildStdin, Command, Stdio};
+use std::sync::atomic::{AtomicBool, Ordering};
+use std::sync::mpsc::{channel, Receiver, RecvTimeoutError, Sender};
+use std::sync::{Arc, Mutex};
+use std::thread;
+use std::time::{Duration, Instant};
+
+const PROTOCOL_VERSION: u64 = 1;
+const STOP_TIMEOUT: Duration = Duration::from_secs(3);
+const POLL: Duration = Duration::from_millis(20);
+const TICK: Duration = Duration::from_millis(50);
+/// Agents may start slowly (node, login); a prompt itself has no limit.
+const HANDSHAKE_TIMEOUT: Duration = Duration::from_secs(120);
+/// After the turn the agent gets this long to exit on its own (flush its session), then dies.
+const EXIT_GRACE: Duration = Duration::from_secs(1);
+const STDERR_MAX: usize = 16 * 1024;
+const METHOD_NOT_FOUND: i64 = -32601;
+/// The Plan card is the existing `TodoWrite` card.
+const PLAN_TOOL: &str = "TodoWrite";
+const SERVER_NAME: &str = "papercraft";
+const BRIDGE: &str = "papercraft-mcp";
+/// How agents prefix MCP tool names; longest first.
+const NAME_PREFIXES: [&str; 4] = ["mcp__papercraft__", "mcp_papercraft_", "papercraft__", "papercraft_"];
+/// Same keys the other backends drop: the agent must run on its own login.
+const CREDENTIAL_ENV: [&str; 4] = ["ANTHROPIC_API_KEY", "ANTHROPIC_AUTH_TOKEN", "OPENAI_API_KEY", "CODEX_API_KEY"];
+
+type Stdin = Arc<Mutex<Option<ChildStdin>>>;
+
+fn send(stdin: &Stdin, v: &Value) -> bool {
+    let mut g = stdin.lock().unwrap();
+    let Some(w) = g.as_mut() else { return false };
+    writeln!(w, "{v}").and_then(|_| w.flush()).is_ok()
+}
+
+/// SIGKILL to the agent's whole process group (it is its own group), so its helpers die too.
+fn kill_tree(child: &mut Child) {
+    #[cfg(unix)]
+    unsafe {
+        libc::kill(-(child.id() as libc::pid_t), libc::SIGKILL);
+    }
+    let _ = child.kill();
+    let _ = child.wait();
+}
+
+pub struct AcpTurn {
+    child: Arc<Mutex<Child>>,
+    stdin: Stdin,
+    session: Arc<Mutex<Option<String>>>,
+    running: Arc<AtomicBool>,
+    stopped: Arc<AtomicBool>,
+    approvals: Sender<(String, bool)>,
+}
+
+impl AcpTurn {
+    /// Answers a `NeedsApproval` event (`id` = the event's id).
+    pub fn approve(&self, id: &str, ok: bool) {
+        let _ = self.approvals.send((id.to_string(), ok));
+    }
+}
+
+impl Turn for AcpTurn {
+    /// Never blocks: the cancel write and the kill timer run on a thread.
+    fn stop(&mut self) {
+        if self.stopped.swap(true, Ordering::SeqCst) {
+            return;
+        }
+        let (child, stdin, session) = (self.child.clone(), self.stdin.clone(), self.session.clone());
+        // The kill timer starts first: a stalled agent can block the cancel write forever.
+        let deadline = Instant::now() + STOP_TIMEOUT;
+        thread::spawn(move || loop {
+            let mut c = child.lock().unwrap();
+            if !matches!(c.try_wait(), Ok(None)) {
+                return;
+            }
+            if Instant::now() >= deadline {
+                kill_tree(&mut c);
+                return;
+            }
+            drop(c);
+            thread::sleep(POLL);
+        });
+        thread::spawn(move || {
+            let sid = session.lock().unwrap().clone();
+            if let Some(sid) = sid {
+                send(&stdin, &json!({"jsonrpc": "2.0", "method": "session/cancel", "params": {"sessionId": sid}}));
+            }
+        });
+    }
+
+    fn is_running(&self) -> bool {
+        self.running.load(Ordering::Acquire)
+    }
+}
+
+/// Starts `program args…` and runs one prompt. Events arrive on `tx`; the last is `TurnEnd` or
+/// `Error`.
+pub fn start(cfg: &TurnConfig, program: &Path, args: &[String], prompt: &str, tx: Sender<Event>) -> Result<AcpTurn, String> {
+    spawn(cfg, program, args, prompt, tx, None)
+}
+
+fn spawn(cfg: &TurnConfig, program: &Path, args: &[String], prompt: &str, tx: Sender<Event>, bridge: Option<PathBuf>) -> Result<AcpTurn, String> {
+    let mut cmd = Command::new(program);
+    cmd.args(args).current_dir(&cfg.project_dir).stdin(Stdio::piped()).stdout(Stdio::piped()).stderr(Stdio::piped());
+    for k in CREDENTIAL_ENV {
+        cmd.env_remove(k);
+    }
+    super::path::apply(&mut cmd);
+    #[cfg(unix)]
+    std::os::unix::process::CommandExt::process_group(&mut cmd, 0);
+    let mut child = cmd.spawn().map_err(|e| format!("Could not start {}: {e}", program.display()))?;
+    let (stdout, mut stderr) = (child.stdout.take().unwrap(), child.stderr.take().unwrap());
+    let stdin: Stdin = Arc::new(Mutex::new(child.stdin.take()));
+    let child = Arc::new(Mutex::new(child));
+    let (approvals, approvals_rx) = channel();
+    let turn = AcpTurn {
+        child: child.clone(),
+        stdin: stdin.clone(),
+        session: Arc::new(Mutex::new(None)),
+        running: Arc::new(AtomicBool::new(true)),
+        stopped: Arc::new(AtomicBool::new(false)),
+        approvals,
+    };
+    let (session, running, stopped) = (turn.session.clone(), turn.running.clone(), turn.stopped.clone());
+
+    let (line_tx, rx) = channel();
+    thread::spawn(move || {
+        for line in BufReader::new(stdout).lines().map_while(Result::ok) {
+            match serde_json::from_str::<Value>(&line) {
+                Ok(v) if v.is_object() => {
+                    if line_tx.send(v).is_err() {
+                        return;
+                    }
+                }
+                _ => log::debug!("acp: skipped non-JSON line: {line}"),
+            }
+        }
+    });
+    let err_text = Arc::new(Mutex::new(String::new()));
+    let err_sink = err_text.clone();
+    thread::spawn(move || {
+        let mut buf = [0u8; 1024];
+        while let Ok(n @ 1..) = stderr.read(&mut buf) {
+            let mut t = err_sink.lock().unwrap();
+            if t.len() < STDERR_MAX {
+                t.push_str(&String::from_utf8_lossy(&buf[..n]));
+            }
+        }
+    });
+
+    let (cfg, prompt, name) = (cfg.clone(), prompt.to_string(), program.display().to_string());
+    thread::spawn(move || {
+        let mut c = Client {
+            rx,
+            stdin: stdin.clone(),
+            approvals: approvals_rx,
+            stopped: stopped.clone(),
+            tx: tx.clone(),
+            next_id: 0,
+            replay: false,
+            pending: HashMap::new(),
+            tools: HashMap::new(),
+            usage: None,
+            cost: None,
+            plans: 0,
+            sid: None,
+        };
+        let result = c.run(&cfg, &prompt, bridge, &session);
+        c.close_open_tools();
+        let end = match result {
+            Ok(stop) => Event::TurnEnd {
+                usage: c.usage.take(),
+                session: c.sid.clone(),
+                stop_reason: Some(if stop == "cancelled" { "stopped".into() } else { stop }),
+            },
+            Err(_) if stopped.load(Ordering::SeqCst) => Event::TurnEnd { usage: None, session: c.sid.clone(), stop_reason: Some("stopped".into()) },
+            Err(e) => {
+                // Give a dying agent a moment to flush its error text.
+                thread::sleep(POLL * 5);
+                let err = err_text.lock().unwrap().trim().to_string();
+                Event::Error(if err.is_empty() { format!("{name}: {e}") } else { format!("{name}: {e}: {}", tail(&err)) })
+            }
+        };
+        // Send first: the app treats "not running" as "everything is in the channel".
+        let _ = tx.send(end);
+        stdin.lock().unwrap().take(); // EOF: a well-behaved agent exits
+        let deadline = Instant::now() + EXIT_GRACE;
+        loop {
+            let mut ch = child.lock().unwrap();
+            if !matches!(ch.try_wait(), Ok(None)) {
+                break;
+            }
+            if Instant::now() >= deadline {
+                kill_tree(&mut ch);
+                break;
+            }
+            drop(ch);
+            thread::sleep(POLL);
+        }
+        running.store(false, Ordering::Release);
+    });
+    Ok(turn)
+}
+
+fn tail(s: &str) -> &str {
+    const KEEP: usize = 600;
+    let mut from = s.len().saturating_sub(KEEP);
+    while !s.is_char_boundary(from) {
+        from += 1;
+    }
+    &s[from..]
+}
+
+struct Tool {
+    name: String,
+    args: Value,
+    ended: bool,
+    /// Announced as one of PaperCraft's own MCP tools (never a shell, edit or fetch).
+    ours: bool,
+}
+
+struct Client {
+    rx: Receiver<Value>,
+    stdin: Stdin,
+    approvals: Receiver<(String, bool)>,
+    stopped: Arc<AtomicBool>,
+    tx: Sender<Event>,
+    next_id: u64,
+    /// `session/load` replays the history as updates; those are not new output.
+    replay: bool,
+    /// Permission requests waiting for the user: tool call id -> (JSON-RPC id, options).
+    pending: HashMap<String, (Value, Vec<Value>)>,
+    tools: HashMap<String, Tool>,
+    usage: Option<Usage>,
+    cost: Option<f64>,
+    plans: u32,
+    sid: Option<String>,
+}
+
+impl Client {
+    fn emit(&self, e: Event) {
+        let _ = self.tx.send(e);
+    }
+
+    fn run(&mut self, cfg: &TurnConfig, prompt: &str, bridge: Option<PathBuf>, slot: &Mutex<Option<String>>) -> Result<String, String> {
+        let init = self.call(
+            "initialize",
+            json!({
+                "protocolVersion": PROTOCOL_VERSION,
+                "clientCapabilities": {"fs": {"readTextFile": false, "writeTextFile": false}, "terminal": false},
+                "clientInfo": {"name": "papercraft", "title": "PaperCraft", "version": env!("CARGO_PKG_VERSION")},
+            }),
+            Some(HANDSHAKE_TIMEOUT),
+        )?;
+        let caps = &init["agentCapabilities"];
+        let http = caps["mcpCapabilities"]["http"] == true;
+        let image = caps["promptCapabilities"]["image"] == true;
+        let bridge = if http { None } else { bridge.or_else(find_bridge) };
+        let session_params = |extra: Value| -> Result<Value, String> {
+            let mut p = json!({"cwd": cfg.project_dir, "mcpServers": mcp_servers(&cfg.mcp_url, http, bridge.as_deref())?});
+            if let (Some(p), Some(extra)) = (p.as_object_mut(), extra.as_object()) {
+                p.extend(extra.clone());
+            }
+            Ok(p)
+        };
+
+        let mut loaded = None;
+        if let Some(id) = cfg.session.as_ref().filter(|_| caps["loadSession"] == true) {
+            self.replay = true;
+            let r = self.call("session/load", session_params(json!({"sessionId": id}))?, Some(HANDSHAKE_TIMEOUT));
+            self.replay = false;
+            match r {
+                Ok(_) => loaded = Some(id.clone()),
+                Err(e) => log::warn!("acp: session/load failed ({e}); starting a new session"),
+            }
+        }
+        let first = loaded.is_none();
+        let sid = match loaded {
+            Some(id) => id,
+            None => {
+                let r = self.call("session/new", session_params(json!({}))?, Some(HANDSHAKE_TIMEOUT))?;
+                r["sessionId"].as_str().ok_or("session/new returned no sessionId")?.to_string()
+            }
+        };
+        self.sid = Some(sid.clone());
+        *slot.lock().unwrap() = Some(sid.clone());
+        self.emit(Event::Session(sid.clone()));
+
+        // ACP has no system prompt: the PaperCraft text leads the first prompt of a session.
+        let mut blocks = vec![];
+        if first && !cfg.system.is_empty() {
+            blocks.push(json!({"type": "text", "text": cfg.system}));
+        }
+        blocks.push(json!({"type": "text", "text": prompt}));
+        if image {
+            blocks.extend(cfg.images.iter().map(|i| json!({"type": "image", "mimeType": i.mime, "data": STANDARD.encode(&i.data)})));
+        }
+        let r = self.call("session/prompt", json!({"sessionId": sid, "prompt": blocks}), None)?;
+        self.usage = usage_of(&r["usage"]).map(|mut u| {
+            u.cost_usd = self.cost;
+            u
+        });
+        if self.usage.is_none() && self.cost.is_some() {
+            self.usage = Some(Usage { cost_usd: self.cost, ..Default::default() });
+        }
+        Ok(r["stopReason"].as_str().unwrap_or("end_turn").to_string())
+    }
+
+    /// Sends a request and serves the agent's messages until its response arrives.
+    fn call(&mut self, method: &str, params: Value, timeout: Option<Duration>) -> Result<Value, String> {
+        let id = self.next_id;
+        self.next_id += 1;
+        if !send(&self.stdin, &json!({"jsonrpc": "2.0", "id": id, "method": method, "params": params})) {
+            return Err("the agent closed its input".into());
+        }
+        let deadline = timeout.map(|t| Instant::now() + t);
+        loop {
+            while let Ok((tool, ok)) = self.approvals.try_recv() {
+                if let Some((rpc, options)) = self.pending.remove(&tool) {
+                    self.answer(&rpc, &options, ok);
+                }
+            }
+            if self.stopped.load(Ordering::SeqCst) {
+                // The spec: every pending permission request gets the `cancelled` outcome.
+                for (_, (rpc, _)) in self.pending.drain() {
+                    send(&self.stdin, &reply(&rpc, json!({"outcome": {"outcome": "cancelled"}})));
+                }
+            }
+            match self.rx.recv_timeout(TICK) {
+                Ok(msg) if msg.get("method").is_some() => self.incoming(&msg),
+                Ok(msg) if msg["id"] == json!(id) => {
+                    return match msg.get("error") {
+                        Some(e) => Err(rpc_error(e)),
+                        None => Ok(msg["result"].clone()),
+                    };
+                }
+                Ok(_) => {}
+                Err(RecvTimeoutError::Timeout) => {
+                    if deadline.is_some_and(|d| Instant::now() >= d) {
+                        return Err(format!("{method} timed out"));
+                    }
+                }
+                Err(RecvTimeoutError::Disconnected) => return Err("the agent exited".into()),
+            }
+        }
+    }
+
+    fn incoming(&mut self, msg: &Value) {
+        let method = msg["method"].as_str().unwrap_or_default();
+        match (method, msg.get("id")) {
+            ("session/update", _) => self.update(&msg["params"]["update"]),
+            ("session/request_permission", Some(id)) => self.permission(id.clone(), &msg["params"]),
+            (m, Some(id)) => {
+                log::debug!("acp: unsupported client method {m}");
+                send(&self.stdin, &json!({"jsonrpc": "2.0", "id": id, "error": {"code": METHOD_NOT_FOUND, "message": format!("method not found: {m}")}}));
+            }
+            (m, None) => log::debug!("acp: ignored notification {m}"),
+        }
+    }
+
+    fn update(&mut self, u: &Value) {
+        if self.replay {
+            return;
+        }
+        let text = |v: &Value| v["content"]["text"].as_str().filter(|t| !t.is_empty()).map(String::from);
+        match u["sessionUpdate"].as_str().unwrap_or_default() {
+            "agent_message_chunk" => text(u).into_iter().for_each(|t| self.emit(Event::Text(t))),
+            "agent_thought_chunk" => text(u).into_iter().for_each(|t| self.emit(Event::Thinking(t))),
+            "tool_call" => self.tool_call(u),
+            "tool_call_update" => {
+                if !self.tools.contains_key(&call_id(u)) {
+                    self.tool_call(u);
+                } else {
+                    self.tool_status(u);
+                }
+            }
+            "plan" => self.plan(u),
+            "usage_update" => {
+                if let Some(used) = u["used"].as_u64() {
+                    self.emit(Event::Context(used));
+                }
+                if u["cost"]["currency"] == "USD" {
+                    self.cost = u["cost"]["amount"].as_f64();
+                }
+            }
+            other => log::debug!("acp: skipped session update {other:?}"),
+        }
+    }
+
+    fn tool_call(&mut self, u: &Value) {
+        let id = call_id(u);
+        if id.is_empty() {
+            return;
+        }
+        let args = if u["rawInput"].is_null() { json!({}) } else { u["rawInput"].clone() };
+        let name = canonical_name(&tool_name(u));
+        let ours = is_ours(&name, u["kind"].as_str());
+        self.tools.insert(id.clone(), Tool { name: name.clone(), args: args.clone(), ended: false, ours });
+        self.emit(Event::ToolStart { id, name, args });
+        self.tool_status(u);
+    }
+
+    fn tool_status(&mut self, u: &Value) {
+        let id = call_id(u);
+        let Some(t) = self.tools.get_mut(&id) else { return };
+        if t.ended || !["completed", "failed"].contains(&u["status"].as_str().unwrap_or_default()) {
+            return;
+        }
+        t.ended = true;
+        let text = content_text(&u["content"]);
+        let ev = if u["status"] == "failed" {
+            let msg = if !text.is_empty() { text } else if u["rawOutput"].is_null() { "tool failed".into() } else { u["rawOutput"].to_string() };
+            Event::ToolEnd { id, result: None, error: Some(msg) }
+        } else {
+            let result = if !text.is_empty() { json!(text) } else if u["rawOutput"].is_null() { json!("") } else { u["rawOutput"].clone() };
+            Event::ToolEnd { id, result: Some(result), error: None }
+        };
+        self.emit(ev);
+    }
+
+    /// A stopped turn leaves tools open; close them so no card spins forever.
+    fn close_open_tools(&mut self) {
+        let open: Vec<String> = self.tools.iter().filter(|(_, t)| !t.ended).map(|(id, _)| id.clone()).collect();
+        for id in open {
+            if let Some(t) = self.tools.get_mut(&id) {
+                t.ended = true;
+            }
+            self.emit(Event::ToolEnd { id, result: None, error: Some(tools::STOPPED_BY_USER.into()) });
+        }
+    }
+
+    fn plan(&mut self, u: &Value) {
+        let Some(entries) = u["entries"].as_array() else { return };
+        let todos: Vec<Value> = entries
+            .iter()
+            .filter_map(|e| {
+                let status = match e["status"].as_str() {
+                    Some(s @ ("in_progress" | "completed")) => s,
+                    _ => "pending",
+                };
+                Some(json!({"content": e["content"].as_str()?, "status": status}))
+            })
+            .collect();
+        self.plans += 1;
+        let id = format!("acp-plan-{}", self.plans);
+        self.emit(Event::ToolStart { id: id.clone(), name: PLAN_TOOL.into(), args: json!({"todos": todos}) });
+        self.emit(Event::ToolEnd { id, result: Some(json!("ok")), error: None });
+    }
+
+    fn permission(&mut self, rpc: Value, params: &Value) {
+        let options = params["options"].as_array().cloned().unwrap_or_default();
+        let tc = &params["toolCall"];
+        let id = call_id(tc);
+        let known = self.tools.get(&id);
+        let name = known.map_or_else(|| canonical_name(&tool_name(tc)), |t| t.name.clone());
+        let args = if !tc["rawInput"].is_null() { tc["rawInput"].clone() } else { known.map_or(json!({}), |t| t.args.clone()) };
+        if known.is_some_and(|t| t.ours) && is_ours(&name, tc["kind"].as_str()) && !tools::needs_approval(&name, &args) {
+            return self.answer(&rpc, &options, true);
+        }
+        self.pending.insert(id.clone(), (rpc, options));
+        self.emit(Event::NeedsApproval { id, name, args });
+    }
+
+    fn answer(&self, rpc: &Value, options: &[Value], allow: bool) {
+        let prefix = if allow { "allow" } else { "reject" };
+        let pick = ["_once", "_always"]
+            .iter()
+            .find_map(|s| options.iter().find(|o| o["kind"] == format!("{prefix}{s}")))
+            .and_then(|o| o["optionId"].as_str());
+        let outcome = match pick {
+            Some(id) => json!({"outcome": "selected", "optionId": id}),
+            None => json!({"outcome": "cancelled"}),
+        };
+        send(&self.stdin, &reply(rpc, json!({"outcome": outcome})));
+    }
+}
+
+fn reply(id: &Value, result: Value) -> Value {
+    json!({"jsonrpc": "2.0", "id": id, "result": result})
+}
+
+fn rpc_error(e: &Value) -> String {
+    let mut m = e["message"].as_str().unwrap_or("request failed").to_string();
+    if let Some(d) = e["data"].as_str().or_else(|| e["data"]["details"].as_str()) {
+        m = format!("{m} ({d})");
+    }
+    m
+}
+
+fn call_id(u: &Value) -> String {
+    u["toolCallId"].as_str().unwrap_or_default().to_string()
+}
+
+/// `name` when the agent sends one, else the human `title`.
+fn tool_name(u: &Value) -> String {
+    u["name"].as_str().or_else(|| u["title"].as_str()).unwrap_or("tool").to_string()
+}
+
+/// Name without the agent's MCP prefix or a trailing ` (papercraft MCP Server)` suffix.
+fn canonical_name(name: &str) -> String {
+    let name = name.trim();
+    let name = match name.rfind(" (") {
+        Some(i) if name.ends_with(')') && name.to_ascii_lowercase()[i..].contains("mcp server") => &name[..i],
+        _ => name,
+    };
+    NAME_PREFIXES.iter().find_map(|p| name.strip_prefix(p)).unwrap_or(name).trim().to_string()
+}
+
+/// A tool of PaperCraft's own MCP server: the canonical name is one of our tools and the kind is
+/// not a built-in agent kind (execute, edit, fetch, delete...).
+fn is_ours(canonical: &str, kind: Option<&str>) -> bool {
+    matches!(kind, None | Some("other")) && tools::tool_specs().iter().any(|t| t["name"] == canonical)
+}
+
+/// Text of a `ToolCallContent` array: `{type:"content", content:{type:"text", text}}` entries.
+fn content_text(v: &Value) -> String {
+    v.as_array()
+        .map(|a| a.iter().filter_map(|c| c["content"]["text"].as_str()).collect::<Vec<_>>().join("\n"))
+        .unwrap_or_default()
+}
+
+/// `{inputTokens, outputTokens, cachedReadTokens, cachedWriteTokens}` of a prompt response.
+fn usage_of(u: &Value) -> Option<Usage> {
+    if !u.is_object() {
+        return None;
+    }
+    let get = |k: &str| u[k].as_u64().unwrap_or(0);
+    Some(Usage { input: get("inputTokens"), output: get("outputTokens"), cache_read: get("cachedReadTokens"), cache_write: get("cachedWriteTokens"), cost_usd: None })
+}
+
+/// PaperCraft's MCP server as an ACP `mcpServers` list: HTTP when the agent supports it, else
+/// the stdio `papercraft-mcp` bridge aimed at the same port.
+fn mcp_servers(url: &str, http: bool, bridge: Option<&Path>) -> Result<Value, String> {
+    if http {
+        return Ok(json!([{"type": "http", "name": SERVER_NAME, "url": url, "headers": []}]));
+    }
+    let bridge = bridge.ok_or("This agent cannot use HTTP MCP servers and the stdio bridge (papercraft-mcp) was not found")?;
+    let port = url.rsplit_once(':').map(|(_, r)| r.split('/').next().unwrap_or_default()).filter(|p| p.parse::<u16>().is_ok());
+    let env: Vec<Value> = port.into_iter().map(|p| json!({"name": "PAPERCRAFT_MCP_PORT", "value": p})).collect();
+    Ok(json!([{"name": SERVER_NAME, "command": bridge, "args": [], "env": env}]))
+}
+
+/// `papercraft-mcp` next to the running executable, else on PATH.
+fn find_bridge() -> Option<PathBuf> {
+    let file = format!("{BRIDGE}{}", std::env::consts::EXE_SUFFIX);
+    std::env::current_exe().ok().and_then(|e| e.parent().map(|d| d.join(&file))).filter(|p| p.is_file()).or_else(|| super::path::which(BRIDGE))
+}
+
+#[cfg(all(test, unix))]
+mod tests {
+    use super::*;
+
+    const AGENT: &str = include_str!("../../tests/fixtures/chat/acp_fake_agent.sh");
+    const HTTP: &str = include_str!("../../tests/fixtures/chat/acp_http.jsonl");
+    const STDIO: &str = include_str!("../../tests/fixtures/chat/acp_stdio.jsonl");
+    const PERMISSION: &str = include_str!("../../tests/fixtures/chat/acp_permission.jsonl");
+    const CANCEL: &str = include_str!("../../tests/fixtures/chat/acp_cancel.jsonl");
+    const LOAD: &str = include_str!("../../tests/fixtures/chat/acp_load.jsonl");
+    const LOAD_FAILS: &str = include_str!("../../tests/fixtures/chat/acp_load_fails.jsonl");
+    const ERROR: &str = include_str!("../../tests/fixtures/chat/acp_error.jsonl");
+
+    fn cfg() -> TurnConfig {
+        TurnConfig { project_dir: std::env::temp_dir(), mcp_url: "http://127.0.0.1:29991/mcp".into(), system: "SYS".into(), ..Default::default() }
+    }
+
+    /// Runs the fake agent on `fixture`; `on` sees every event and may approve or stop. Returns
+    /// the events and the JSON lines the client wrote.
+    fn run(fixture: &str, cfg: TurnConfig, bridge: Option<PathBuf>, mut on: impl FnMut(&mut AcpTurn, &Event)) -> (Vec<Event>, Vec<Value>) {
+        let dir = std::env::temp_dir().join(format!("pc-acp-{}", fastrand::u64(..)));
+        std::fs::create_dir_all(&dir).unwrap();
+        let (script, fx, log) = (dir.join("agent.sh"), dir.join("fixture.jsonl"), dir.join("client.log"));
+        std::fs::write(&script, AGENT).unwrap();
+        std::fs::write(&fx, fixture).unwrap();
+        let args: Vec<String> = [&script, &fx, &log].iter().map(|p| p.display().to_string()).collect();
+        let (tx, rx) = channel();
+        let mut turn = spawn(&cfg, Path::new("/bin/sh"), &args, "hello", tx, bridge).unwrap();
+        let mut events = vec![];
+        loop {
+            let e = rx.recv_timeout(Duration::from_secs(15)).expect("turn timed out");
+            on(&mut turn, &e);
+            let done = matches!(e, Event::TurnEnd { .. } | Event::Error(_));
+            events.push(e);
+            if done {
+                break;
+            }
+        }
+        let t = Instant::now();
+        while turn.is_running() && t.elapsed() < Duration::from_secs(5) {
+            thread::sleep(POLL);
+        }
+        assert!(!turn.is_running());
+        let sent = std::fs::read_to_string(&log).unwrap_or_default().lines().map(|l| serde_json::from_str(l).unwrap()).collect();
+        std::fs::remove_dir_all(&dir).unwrap();
+        (events, sent)
+    }
+
+    fn method<'a>(sent: &'a [Value], m: &str) -> &'a Value {
+        sent.iter().find(|v| v["method"] == m).unwrap_or_else(|| panic!("no {m} in {sent:?}"))
+    }
+
+    #[test]
+    fn http_handshake_streaming_tools_plan() {
+        let mut c = cfg();
+        c.images = vec![super::super::events::ImageAttachment { mime: "image/png".into(), data: vec![1, 2, 3] }];
+        let (ev, sent) = run(HTTP, c, None, |_, _| {});
+        let init = &method(&sent, "initialize")["params"];
+        assert_eq!(init["protocolVersion"], 1);
+        assert_eq!(init["clientCapabilities"], json!({"fs": {"readTextFile": false, "writeTextFile": false}, "terminal": false}));
+        let new = &method(&sent, "session/new")["params"];
+        assert_eq!(new["mcpServers"], json!([{"type": "http", "name": "papercraft", "url": "http://127.0.0.1:29991/mcp", "headers": []}]));
+        assert_eq!(new["cwd"], json!(std::env::temp_dir()));
+        let prompt = &method(&sent, "session/prompt")["params"];
+        assert_eq!(prompt["sessionId"], "sess-1");
+        assert_eq!(
+            prompt["prompt"],
+            json!([{"type": "text", "text": "SYS"}, {"type": "text", "text": "hello"}, {"type": "image", "mimeType": "image/png", "data": "AQID"}])
+        );
+        // unknown client request answered with -32601
+        assert_eq!(sent.iter().find(|v| v["id"] == 50).unwrap()["error"]["code"], METHOD_NOT_FOUND);
+
+        assert_eq!(ev[0], Event::Session("sess-1".into()));
+        assert_eq!(ev[1], Event::Thinking("hmm".into()));
+        assert_eq!(ev[2], Event::Text("Hel".into()));
+        assert_eq!(ev[3], Event::Text("lo".into()));
+        assert_eq!(ev[4], Event::ToolStart { id: "t1".into(), name: "get_basic_info".into(), args: json!({}) });
+        assert_eq!(ev[5], Event::ToolEnd { id: "t1".into(), result: Some(json!("{\"ok\":true}")), error: None });
+        assert_eq!(ev[6], Event::ToolStart { id: "t2".into(), name: "ls".into(), args: json!({"path": "."}) });
+        assert_eq!(ev[7], Event::ToolEnd { id: "t2".into(), result: None, error: Some("denied".into()) });
+        assert_eq!(ev[8], Event::ToolStart { id: "acp-plan-1".into(), name: "TodoWrite".into(), args: json!({"todos": [{"content": "A", "status": "completed"}, {"content": "B", "status": "pending"}]}) });
+        assert_eq!(ev[9], Event::ToolEnd { id: "acp-plan-1".into(), result: Some(json!("ok")), error: None });
+        assert_eq!(ev[10], Event::Context(5000));
+        let Event::TurnEnd { usage: Some(u), session: Some(s), stop_reason: Some(r) } = &ev[11] else { panic!("{:?}", ev[11]) };
+        assert_eq!((u.input, u.output, u.cost_usd, s.as_str(), r.as_str()), (7, 3, Some(0.5), "sess-1", "end_turn"));
+        assert_eq!(ev.len(), 12);
+    }
+
+    #[test]
+    fn stdio_bridge_when_no_http() {
+        let (ev, sent) = run(STDIO, cfg(), Some("/fake/papercraft-mcp".into()), |_, _| {});
+        assert_eq!(
+            method(&sent, "session/new")["params"]["mcpServers"],
+            json!([{"name": "papercraft", "command": "/fake/papercraft-mcp", "args": [], "env": [{"name": "PAPERCRAFT_MCP_PORT", "value": "29991"}]}])
+        );
+        assert_eq!(method(&sent, "session/prompt")["params"]["prompt"].as_array().unwrap().len(), 2);
+        assert!(matches!(ev.last(), Some(Event::TurnEnd { stop_reason: Some(r), .. }) if r == "max_tokens"));
+    }
+
+    #[test]
+    fn permissions_auto_and_asked() {
+        let (ev, sent) = run(PERMISSION, cfg(), None, |turn, e| {
+            if let Event::NeedsApproval { id, .. } = e {
+                turn.approve(id, id == "t-del");
+            }
+        });
+        let asked: Vec<_> = ev.iter().filter_map(|e| if let Event::NeedsApproval { id, name, .. } = e { Some((id.as_str(), name.as_str())) } else { None }).collect();
+        assert_eq!(asked, [("t-del", "delete_pages"), ("t-sh", "Run ls")]);
+        let answer = |rpc: u64| sent.iter().find(|v| v["id"] == rpc).unwrap()["result"]["outcome"].clone();
+        assert_eq!(answer(100), json!({"outcome": "selected", "optionId": "allow-once"}));
+        assert_eq!(answer(101), json!({"outcome": "selected", "optionId": "allow-once"}));
+        assert_eq!(answer(102), json!({"outcome": "selected", "optionId": "reject-once"}));
+        assert!(matches!(ev.last(), Some(Event::TurnEnd { .. })));
+    }
+
+    #[test]
+    fn cancel_sends_notification_and_reports_stopped() {
+        let t = Instant::now();
+        let (ev, sent) = run(CANCEL, cfg(), None, |turn, e| {
+            if matches!(e, Event::Text(_)) {
+                turn.stop();
+            }
+        });
+        assert_eq!(method(&sent, "session/cancel")["params"]["sessionId"], "sess-1");
+        assert!(sent.iter().find(|v| v["method"] == "session/cancel").unwrap().get("id").is_none());
+        // the open tool is closed, the pending permission got `cancelled`
+        assert!(ev.iter().any(|e| matches!(e, Event::ToolEnd { id, error: Some(_), .. } if id == "t1")));
+        assert_eq!(sent.iter().find(|v| v["id"] == 100).unwrap()["result"]["outcome"], json!({"outcome": "cancelled"}));
+        assert!(matches!(ev.last(), Some(Event::TurnEnd { stop_reason: Some(r), .. }) if r == "stopped"));
+        assert!(t.elapsed() < Duration::from_secs(3));
+    }
+
+    #[test]
+    fn stop_kills_an_agent_that_ignores_cancel() {
+        let (tx, rx) = channel();
+        let args = ["-c".to_string(), "trap '' INT TERM; while :; do sleep 1; done".to_string()];
+        let mut turn = spawn(&cfg(), Path::new("/bin/sh"), &args, "x", tx, None).unwrap();
+        thread::sleep(Duration::from_millis(100));
+        let t = Instant::now();
+        turn.stop();
+        assert!(t.elapsed() < Duration::from_millis(200), "stop blocked");
+        assert!(matches!(rx.recv_timeout(Duration::from_secs(8)), Ok(Event::TurnEnd { stop_reason: Some(r), .. }) if r == "stopped"));
+        let t = Instant::now();
+        while turn.is_running() && t.elapsed() < Duration::from_secs(5) {
+            thread::sleep(POLL);
+        }
+        assert!(!turn.is_running());
+    }
+
+    #[test]
+    fn load_replays_silently_and_skips_the_system_text() {
+        let mut c = cfg();
+        c.session = Some("old".into());
+        let (ev, sent) = run(LOAD, c, None, |_, _| {});
+        let load = &method(&sent, "session/load")["params"];
+        assert_eq!(load["sessionId"], "old");
+        assert!(load["mcpServers"].is_array());
+        assert!(sent.iter().all(|v| v["method"] != "session/new"));
+        assert_eq!(method(&sent, "session/prompt")["params"]["prompt"], json!([{"type": "text", "text": "hello"}]));
+        assert_eq!(ev[0], Event::Session("old".into()));
+        assert_eq!(ev[1], Event::Text("fresh".into()), "replayed history must not surface: {ev:?}");
+        assert!(matches!(&ev[2], Event::TurnEnd { session: Some(s), .. } if s == "old"));
+    }
+
+    #[test]
+    fn failed_load_falls_back_to_new_session() {
+        let mut c = cfg();
+        c.session = Some("gone".into());
+        let (ev, sent) = run(LOAD_FAILS, c, None, |_, _| {});
+        assert_eq!(method(&sent, "session/prompt")["params"]["prompt"][0]["text"], "SYS");
+        assert_eq!(ev[0], Event::Session("sess-new".into()));
+    }
+
+    #[test]
+    fn rpc_error_becomes_error_event() {
+        let (ev, _) = run(ERROR, cfg(), None, |_, _| {});
+        assert!(matches!(ev.last(), Some(Event::Error(e)) if e.contains("Authentication required")), "{ev:?}");
+    }
+
+    #[test]
+    fn missing_program_is_an_error() {
+        let (tx, _rx) = channel();
+        assert!(spawn(&cfg(), Path::new("/nonexistent/agent"), &[], "x", tx, None).is_err());
+    }
+
+    #[test]
+    fn tool_names_and_papercraft_detection() {
+        assert_eq!(canonical_name("mcp__papercraft__get_basic_info"), "get_basic_info");
+        assert_eq!(canonical_name("papercraft_x"), "x");
+        assert_eq!(canonical_name("Read file"), "Read file");
+        assert_eq!(canonical_name("delete_pages (papercraft MCP Server)"), "delete_pages");
+        assert!(is_ours("get_basic_info", Some("other")));
+        assert!(!is_ours("get_basic_info", Some("execute")));
+        assert!(!is_ours("rm -rf papercraft", None));
+        assert!(!is_ours("bogus", None));
+        assert_eq!(mcp_servers("http://x:1/mcp", false, None).unwrap_err().contains("papercraft-mcp"), true);
+    }
+
+    #[test]
+    fn permission_trust_needs_an_announced_papercraft_tool() {
+        // title-only differences, unannounced ids, execute kind and suffixed destructive names all ask
+        let fx = [
+            r#"{"sessionUpdate":"tool_call","toolCallId":"a","title":"get_basic_info (papercraft MCP Server)","kind":"other","rawInput":{}}"#,
+            r#"{"sessionUpdate":"tool_call","toolCallId":"b","title":"Run ls","kind":"execute","rawInput":{}}"#,
+            r#"{"sessionUpdate":"tool_call","toolCallId":"d","title":"delete_pages (papercraft MCP Server)","kind":"other","rawInput":{}}"#,
+        ];
+        let (tx, rx) = channel();
+        let (stdin, _) = (Arc::new(Mutex::new(None)), ());
+        let mut c = Client { rx: channel().1, stdin, approvals: channel().1, stopped: Arc::new(AtomicBool::new(false)), tx, next_id: 0, replay: false, pending: HashMap::new(), tools: HashMap::new(), usage: None, cost: None, plans: 0, sid: None };
+        for u in fx {
+            c.update(&serde_json::from_str(u).unwrap());
+        }
+        for (id, title, asked) in [("a", "get_basic_info (papercraft MCP Server)", false), ("b", "Run ls", true), ("d", "delete_pages (papercraft MCP Server)", true), ("zz", "get_basic_info", true), ("b", "get_basic_info", true)] {
+            c.pending.clear();
+            c.permission(json!(1), &json!({"toolCall": {"toolCallId": id, "title": title}, "options": []}));
+            assert_eq!(c.pending.contains_key(id), asked, "{id} {title}");
+        }
+        drop(rx);
+    }
+
+    #[test]
+    fn stop_kills_even_when_the_cancel_write_blocks() {
+        let (tx, rx) = channel();
+        // never reads stdin; a big write fills the pipe and blocks
+        let args = ["-c".to_string(), "trap '' INT TERM; while :; do sleep 1; done".to_string()];
+        let mut turn = spawn(&cfg(), Path::new("/bin/sh"), &args, "x", tx, None).unwrap();
+        *turn.session.lock().unwrap() = Some("s".repeat(1 << 20));
+        thread::sleep(Duration::from_millis(100));
+        turn.stop();
+        assert!(matches!(rx.recv_timeout(Duration::from_secs(8)), Ok(Event::TurnEnd { stop_reason: Some(r), .. }) if r == "stopped"));
+    }
+}
@@ -0,0 +1,365 @@
+//! The agent registry: every coding agent PaperCraft knows how to start, as data, plus detection
+//! on the resolved PATH and the command that launches one over ACP.
+//!
+//! Launch args were checked against the agents installed on the dev machine (2026-10-21):
+//! * Gemini CLI 0.44.1: `gemini --acp` (`--help` lists `--acp`; `--experimental-acp` is deprecated).
+//! * OpenCode 1.18.30: `opencode acp` ("start ACP (Agent Client Protocol) server").
+//! * Cursor Agent 2026.03.20: the binary is `cursor-agent` (its help says `agent`); `cursor-agent acp`
+//!   ("Start the Cursor Agent as an ACP server").
+//! * Pi 0.80.3 has no ACP mode of its own; the `pi-acp` adapter is run with `npx`.
+//! * Goose: `/opt/homebrew/bin/goose` here is pressly/goose, the SQL migration tool. Block's agent
+//!   has an `acp` subcommand; the migration tool's `--help` never says `acp`, so that is the identity.
+//! The rest keep their documented command and fail with the agent's own error.
+
+#[cfg(not(target_arch = "wasm32"))]
+use crate::ui::settings::ChatPrefs;
+#[cfg(not(target_arch = "wasm32"))]
+use crate::ui::settings::CustomAgent;
+#[cfg(not(target_arch = "wasm32"))]
+use std::path::PathBuf;
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum AgentKind {
+    /// A program found on PATH that speaks ACP.
+    Native,
+    /// Run with `npx -y <package>`; off until the user enables it, because that runs fetched code.
+    Npx { package: &'static str },
+    /// Claude Code and Codex: proven direct backends, not started through ACP.
+    Direct,
+}
+
+#[derive(Debug, Clone, Copy)]
+pub struct AgentDef {
+    pub id: &'static str,
+    pub name: &'static str,
+    pub binary: &'static str,
+    /// Args after the binary (or after the package for `Npx`) that start ACP mode.
+    pub launch: &'static [&'static str],
+    pub kind: AgentKind,
+    pub docs_url: &'static str,
+    /// Text (case-insensitive) that `--version` or `--help` of the real program contains.
+    pub identity: Option<&'static str>,
+}
+
+const fn native(id: &'static str, name: &'static str, binary: &'static str, launch: &'static [&'static str], docs_url: &'static str, identity: Option<&'static str>) -> AgentDef {
+    AgentDef { id, name, binary, launch, kind: AgentKind::Native, docs_url, identity }
+}
+
+const fn npx(id: &'static str, name: &'static str, package: &'static str, launch: &'static [&'static str], docs_url: &'static str) -> AgentDef {
+    AgentDef { id, name, binary: "npx", launch, kind: AgentKind::Npx { package }, docs_url, identity: None }
+}
+
+pub const AGENTS: &[AgentDef] = &[
+    AgentDef { id: "claude-code", name: "Claude Code", binary: "claude", launch: &[], kind: AgentKind::Direct, docs_url: super::CLAUDE_DOCS, identity: Some("claude code") },
+    AgentDef { id: "codex", name: "Codex", binary: "codex", launch: &[], kind: AgentKind::Direct, docs_url: super::CODEX_DOCS, identity: Some("codex") },
+    native("gemini", "Gemini CLI", "gemini", &["--acp"], "https://github.com/google-gemini/gemini-cli", Some("gemini cli")),
+    native("cursor", "Cursor", "cursor-agent", &["acp"], "https://cursor.com/cli", Some("cursor agent")),
+    native("opencode", "OpenCode", "opencode", &["acp"], "https://opencode.ai/docs", Some("opencode")),
+    native("goose", "Goose", "goose", &["acp"], "https://block.github.io/goose", Some("acp")),
+    native("kimi", "Kimi", "kimi", &["acp"], "https://github.com/MoonshotAI/kimi-cli", None),
+    native("devin", "Devin", "devin", &["acp"], "https://docs.devin.ai", None),
+    native("junie", "Junie", "junie", &["--acp=true"], "https://www.jetbrains.com/junie", None),
+    native("vibe", "Mistral Vibe", "vibe-acp", &[], "https://github.com/mistralai/mistral-vibe", None),
+    native("hermes", "Hermes", "hermes", &["acp"], "https://github.com/NousResearch/hermes-agent", None),
+    native("openhands", "OpenHands", "openhands", &["acp"], "https://docs.all-hands.dev", None),
+    native("stakpak", "Stakpak", "stakpak", &["acp"], "https://github.com/stakpak/agent", None),
+    native("vtcode", "VT Code", "vtcode", &["acp"], "https://github.com/vinhnx/vtcode", None),
+    native("poolside", "Poolside", "pool", &["acp"], "https://poolside.ai", None),
+    native("droid", "Droid", "droid", &["exec", "--output-format", "acp-daemon"], "https://docs.factory.ai", None),
+    npx("qwen", "Qwen Code", "@qwen-code/qwen-code", &["--acp"], "https://github.com/QwenLM/qwen-code"),
+    npx("kilo", "Kilo", "@kilocode/cli", &["acp"], "https://kilo.ai/docs"),
+    npx("cline", "Cline", "cline", &["--acp"], "https://docs.cline.bot"),
+    npx("auggie", "Auggie", "@augmentcode/auggie", &["--acp"], "https://docs.augmentcode.com"),
+    npx("copilot", "Copilot CLI", "@github/copilot", &["--acp"], "https://docs.github.com/copilot"),
+    npx("qoder", "Qoder", "@qoder-ai/qodercli", &["--acp"], "https://qoder.com"),
+    npx("codebuddy", "CodeBuddy", "@tencent-ai/codebuddy-code", &["--acp"], "https://www.codebuddy.ai"),
+    npx("pi", "Pi", "pi-acp", &[], "https://github.com/svkozak/pi-acp"),
+    npx("claude-acp", "Claude Code (ACP adapter)", "@zed-industries/claude-code-acp", &[], "https://github.com/zed-industries/claude-code-acp"),
+    npx("codex-acp", "Codex (ACP adapter)", "@zed-industries/codex-acp", &[], "https://github.com/zed-industries/codex-acp"),
+];
+
+pub fn find(id: &str) -> Option<&'static AgentDef> {
+    AGENTS.iter().find(|a| a.id == id)
+}
+
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub enum AgentState {
+    Ready { path: String, version: String },
+    /// An `npx` agent the user has not turned on.
+    NeedsEnable,
+    NotFound,
+    /// A program with the right name that is not the agent (e.g. the `goose` migration tool).
+    WrongProgram { path: String },
+}
+
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct AgentStatus {
+    pub id: String,
+    pub state: AgentState,
+}
+
+/// Registry agents then custom ones.
+#[cfg(not(target_arch = "wasm32"))]
+pub fn detect_all(prefs: &ChatPrefs) -> Vec<AgentStatus> {
+    detect_all_in(prefs, super::path::resolved_path().as_ref())
+}
+
+#[cfg(not(target_arch = "wasm32"))]
+fn detect_all_in(prefs: &ChatPrefs, path: &std::ffi::OsStr) -> Vec<AgentStatus> {
+    // One thread per agent: each probe can wait out its timeout.
+    std::thread::scope(|s| {
+        let jobs: Vec<_> = AGENTS
+            .iter()
+            .map(|d| (d.id.to_owned(), s.spawn(move || detect_def(d, prefs, path))))
+            .chain(prefs.custom_agents.iter().map(|c| (c.id.clone(), s.spawn(move || detect_custom(c, path)))))
+            .collect();
+        jobs.into_iter().map(|(id, j)| AgentStatus { id, state: j.join().unwrap_or(AgentState::NotFound) }).collect()
+    })
+}
+
+#[cfg(not(target_arch = "wasm32"))]
+const PROBE_TIMEOUT: std::time::Duration = std::time::Duration::from_secs(4); // macOS scans a program on its first run, which can take seconds under load
+/// `--help` of a node CLI can take a moment longer than `--version`.
+#[cfg(not(target_arch = "wasm32"))]
+const HELP_TIMEOUT: std::time::Duration = std::time::Duration::from_secs(5);
+#[cfg(not(target_arch = "wasm32"))]
+const PROBE_MAX_BYTES: u64 = 64 * 1024;
+
+/// The override from Settings, if any. The old `claude_path`/`codex_path` fields win for their
+/// agent until Settings writes `agents` instead.
+#[cfg(not(target_arch = "wasm32"))]
+fn path_override<'a>(id: &str, prefs: &'a ChatPrefs) -> Option<&'a str> {
+    let legacy = match id {
+        "claude-code" => prefs.claude_path.as_deref(),
+        "codex" => prefs.codex_path.as_deref(),
+        _ => None,
+    };
+    legacy.or_else(|| prefs.agents.get(id)?.path.as_deref()).map(str::trim).filter(|p| !p.is_empty())
+}
+
+#[cfg(not(target_arch = "wasm32"))]
+fn args_override<'a>(id: &str, prefs: &'a ChatPrefs) -> Option<&'a str> {
+    prefs.agents.get(id)?.args.as_deref().map(str::trim).filter(|a| !a.is_empty())
+}
+
+#[cfg(not(target_arch = "wasm32"))]
+fn is_enabled(def: &AgentDef, prefs: &ChatPrefs) -> bool {
+    !matches!(def.kind, AgentKind::Npx { .. }) || prefs.agents.get(def.id).is_some_and(|a| a.enabled)
+}
+
+#[cfg(not(target_arch = "wasm32"))]
+fn locate(binary: &str, over: Option<&str>, path: &std::ffi::OsStr) -> Option<PathBuf> {
+    match over {
+        Some(p) => PathBuf::from(p).is_file().then(|| PathBuf::from(p)),
+        None => super::path::which_in(binary, path),
+    }
+}
+
+#[cfg(not(target_arch = "wasm32"))]
+fn detect_def(def: &AgentDef, prefs: &ChatPrefs, path: &std::ffi::OsStr) -> AgentState {
+    let over = path_override(def.id, prefs);
+    if !is_enabled(def, prefs) {
+        return AgentState::NeedsEnable;
+    }
+    // An npx agent needs npx itself; a path override points at that program instead.
+    let Some(bin) = locate(def.binary, over, path) else { return AgentState::NotFound };
+    let shown = bin.display().to_string();
+    if matches!(def.kind, AgentKind::Npx { .. }) {
+        return AgentState::Ready { path: shown, version: String::new() };
+    }
+    let version = probe(&bin, "--version", path, PROBE_TIMEOUT);
+    if let Some(want) = def.identity {
+        let hit = |o: &Option<String>| o.as_ref().is_some_and(|o| o.to_lowercase().contains(want));
+        if !hit(&version) && !hit(&probe(&bin, "--help", path, HELP_TIMEOUT)) {
+            return AgentState::WrongProgram { path: shown };
+        }
+    }
+    AgentState::Ready { path: shown, version: version.as_deref().and_then(|v| v.lines().find(|l| !l.trim().is_empty())).unwrap_or_default().trim().to_owned() }
+}
+
+#[cfg(not(target_arch = "wasm32"))]
+fn detect_custom(c: &CustomAgent, path: &std::ffi::OsStr) -> AgentState {
+    match custom_program(c, path) {
+        Some(p) => AgentState::Ready { path: p.display().to_string(), version: String::new() },
+        None => AgentState::NotFound,
+    }
+}
+
+#[cfg(not(target_arch = "wasm32"))]
+fn custom_program(c: &CustomAgent, path: &std::ffi::OsStr) -> Option<PathBuf> {
+    let cmd = c.command.trim();
+    if cmd.is_empty() {
+        return None;
+    }
+    if cmd.contains(['/', '\\']) {
+        return PathBuf::from(cmd).is_file().then(|| PathBuf::from(cmd));
+    }
+    super::path::which_in(cmd, path)
+}
+
+/// Runs `bin arg` and returns stdout + stderr; None when it fails to start or times out. No
+/// credentials in the environment, PATH as the agents get it.
+#[cfg(not(target_arch = "wasm32"))]
+fn probe(bin: &std::path::Path, arg: &str, path: &std::ffi::OsStr, timeout: std::time::Duration) -> Option<String> {
+    use std::io::Read;
+    use std::process::{Command, Stdio};
+    let mut cmd = Command::new(bin);
+    cmd.arg(arg).env("PATH", path).stdin(Stdio::null()).stdout(Stdio::piped()).stderr(Stdio::piped());
+    for k in super::path::CREDENTIAL_ENV {
+        cmd.env_remove(k);
+    }
+    // ETXTBSY (26): a binary just written (installer, test) is briefly still open for writing.
+    let mut child = (0..5).find_map(|_| match cmd.spawn() {
+        Err(e) if e.raw_os_error() == Some(26) => {
+            std::thread::sleep(std::time::Duration::from_millis(30));
+            None
+        }
+        r => Some(r),
+    })?.ok()?;
+    let (tx, rx) = std::sync::mpsc::channel();
+    for pipe in [child.stdout.take().map(|p| Box::new(p) as Box<dyn Read + Send>), child.stderr.take().map(|p| Box::new(p) as Box<dyn Read + Send>)].into_iter().flatten() {
+        let tx = tx.clone();
+        std::thread::spawn(move || {
+            let mut s = String::new();
+            let _ = pipe.take(PROBE_MAX_BYTES).read_to_string(&mut s);
+            let _ = tx.send(s);
+        });
+    }
+    drop(tx);
+    // Both pipes close when the program exits; a hung program hits the deadline and is killed.
+    let deadline = std::time::Instant::now() + timeout;
+    let mut out = String::new();
+    let done = loop {
+        match rx.recv_timeout(deadline.saturating_duration_since(std::time::Instant::now())) {
+            Ok(s) => out.push_str(&s),
+            Err(std::sync::mpsc::RecvTimeoutError::Disconnected) => break true,
+            Err(_) => break false,
+        }
+    };
+    let _ = child.kill();
+    let _ = child.wait();
+    done.then_some(out)
+}
+
+/// What the ACP backend runs for this agent: program and args. None for an unknown id, a
+/// `Direct` agent, an `npx` agent that is not enabled, or a program that is not on PATH.
+#[cfg(not(target_arch = "wasm32"))]
+pub fn launch_command(id: &str, prefs: &ChatPrefs) -> Option<(PathBuf, Vec<String>)> {
+    launch_command_in(id, prefs, super::path::resolved_path().as_ref())
+}
+
+#[cfg(not(target_arch = "wasm32"))]
+fn launch_command_in(id: &str, prefs: &ChatPrefs, path: &std::ffi::OsStr) -> Option<(PathBuf, Vec<String>)> {
+    if let Some(c) = prefs.custom_agents.iter().find(|c| c.id == id) {
+        return Some((custom_program(c, path)?, split(&c.args)));
+    }
+    let def = find(id)?;
+    if !is_enabled(def, prefs) {
+        return None;
+    }
+    let program = locate(def.binary, path_override(id, prefs), path)?;
+    let args = args_override(id, prefs).map_or_else(|| def.launch.iter().map(|a| (*a).to_owned()).collect(), split);
+    match def.kind {
+        AgentKind::Native => Some((program, args)),
+        AgentKind::Npx { package } => Some((program, ["-y".to_owned(), package.to_owned()].into_iter().chain(args).collect())),
+        AgentKind::Direct => None,
+    }
+}
+
+// ponytail: whitespace split, no quoting; add shlex if a path with spaces is ever needed in args.
+#[cfg(not(target_arch = "wasm32"))]
+fn split(args: &str) -> Vec<String> {
+    args.split_whitespace().map(String::from).collect()
+}
+
+#[cfg(all(test, unix))]
+mod tests {
+    use super::*;
+    use crate::ui::settings::AgentPrefs;
+    use std::ffi::OsString;
+    use std::os::unix::fs::PermissionsExt;
+
+    fn fake_dir(scripts: &[(&str, &str)]) -> (PathBuf, OsString) {
+        let dir = std::env::temp_dir().join(format!("pc-agents-{}", fastrand::u64(..)));
+        std::fs::create_dir_all(&dir).unwrap();
+        for (name, body) in scripts {
+            let p = dir.join(name);
+            std::fs::write(&p, format!("#!/bin/sh\n{body}\n")).unwrap();
+            std::fs::set_permissions(&p, std::fs::Permissions::from_mode(0o755)).unwrap();
+        }
+        let path = dir.clone().into_os_string();
+        (dir, path)
+    }
+
+    fn state(all: &[AgentStatus], id: &str) -> AgentState {
+        all.iter().find(|s| s.id == id).unwrap().state.clone()
+    }
+
+    #[test]
+    fn table_ids_are_unique_and_launchable() {
+        let mut ids: Vec<_> = AGENTS.iter().map(|a| a.id).collect();
+        ids.sort_unstable();
+        ids.dedup();
+        assert_eq!(ids.len(), AGENTS.len());
+        assert!(AGENTS.iter().all(|a| !a.name.is_empty() && !a.binary.is_empty() && a.docs_url.starts_with("https://")));
+        assert!(AGENTS.iter().all(|a| !matches!(a.kind, AgentKind::Native) || !a.launch.is_empty() || a.id == "vibe"));
+    }
+
+    #[test]
+    fn detects_ready_wrong_missing_and_npx_states() {
+        let (dir, path) = fake_dir(&[
+            ("gemini", r#"if [ "$1" = --version ]; then echo 0.1.0; else echo "Gemini CLI help"; fi"#),
+            // The migration tool: version string and help with no "acp".
+            ("goose", r#"if [ "$1" = --version ]; then echo "goose version: v3.27.1"; else echo "Usage: goose DRIVER DBSTRING"; fi"#),
+            ("opencode", r#"echo "opencode 1.0""#),
+            ("npx", "echo npx"),
+        ]);
+        let mut prefs = ChatPrefs::default();
+        let all = detect_all_in(&prefs, &path);
+        assert_eq!(all.len(), AGENTS.len());
+        let shown = |n: &str| dir.join(n).display().to_string();
+        assert_eq!(state(&all, "gemini"), AgentState::Ready { path: shown("gemini"), version: "0.1.0".into() });
+        assert_eq!(state(&all, "opencode"), AgentState::Ready { path: shown("opencode"), version: "opencode 1.0".into() });
+        assert_eq!(state(&all, "goose"), AgentState::WrongProgram { path: shown("goose") });
+        assert_eq!(state(&all, "cursor"), AgentState::NotFound);
+        assert_eq!(state(&all, "pi"), AgentState::NeedsEnable);
+        prefs.agents.insert("pi".into(), AgentPrefs { enabled: true, ..Default::default() });
+        assert_eq!(state(&detect_all_in(&prefs, &path), "pi"), AgentState::Ready { path: shown("npx"), version: String::new() });
+        // Enabled but npx missing.
+        assert_eq!(state(&detect_all_in(&prefs, OsStr::new("/nonexistent")), "pi"), AgentState::NotFound);
+        std::fs::remove_dir_all(&dir).unwrap();
+    }
+
+    use std::ffi::OsStr;
+
+    #[test]
+    fn path_override_wins_and_hung_program_times_out() {
+        let (dir, path) = fake_dir(&[("opencode", "echo opencode"), ("hang", "sleep 30")]);
+        let mut prefs = ChatPrefs::default();
+        prefs.agents.insert("opencode".into(), AgentPrefs { path: Some("/nonexistent/opencode".into()), ..Default::default() });
+        assert_eq!(state(&detect_all_in(&prefs, &path), "opencode"), AgentState::NotFound);
+        let t = std::time::Instant::now();
+        assert_eq!(probe(&dir.join("hang"), "--version", &path, std::time::Duration::from_millis(200)), None);
+        assert!(t.elapsed() < std::time::Duration::from_secs(5));
+        std::fs::remove_dir_all(&dir).unwrap();
+    }
+
+    #[test]
+    fn launch_commands_for_native_npx_custom_and_direct() {
+        let (dir, path) = fake_dir(&[("gemini", ""), ("npx", ""), ("my-agent", "")]);
+        let mut prefs = ChatPrefs::default();
+        prefs.custom_agents.push(CustomAgent { id: "mine".into(), name: "Mine".into(), command: "my-agent".into(), args: "serve  --stdio".into() });
+        let at = |n: &str| dir.join(n);
+        assert_eq!(launch_command_in("gemini", &prefs, &path), Some((at("gemini"), vec!["--acp".into()])));
+        assert_eq!(launch_command_in("mine", &prefs, &path), Some((at("my-agent"), vec!["serve".into(), "--stdio".into()])));
+        assert_eq!(launch_command_in("pi", &prefs, &path), None);
+        prefs.agents.insert("pi".into(), AgentPrefs { enabled: true, ..Default::default() });
+        assert_eq!(launch_command_in("pi", &prefs, &path), Some((at("npx"), vec!["-y".into(), "pi-acp".into()])));
+        prefs.agents.insert("gemini".into(), AgentPrefs { args: Some("--acp --debug".into()), ..Default::default() });
+        assert_eq!(launch_command_in("gemini", &prefs, &path).unwrap().1, ["--acp", "--debug"]);
+        assert_eq!(launch_command_in("claude-code", &prefs, &path), None);
+        assert_eq!(launch_command_in("nope", &prefs, &path), None);
+        assert_eq!(launch_command_in("cursor", &prefs, &path), None);
+        std::fs::remove_dir_all(&dir).unwrap();
+    }
+}
@@ -0,0 +1,589 @@
+//! Parser for `claude -p --output-format stream-json --verbose [--include-partial-messages]` lines.
+//! Pure: one JSON line in, zero or more [`Event`]s out.
+//!
+//! Without partial messages the text arrives in whole `assistant` messages ([`parse_line`]). With
+//! `--include-partial-messages` the CLI emits `stream_event` deltas AND the whole `assistant`
+//! messages, so [`parse_line_partial`] takes text/thinking from the deltas and only tool calls
+//! from the whole messages (their input is complete there).
+
+use super::events::{content_text, str_of, Event};
+use super::Usage;
+use serde_json::Value;
+
+/// MCP tools reach the model as `mcp__<server>__<tool>`; the UI wants the bare tool name.
+const MCP_PREFIX: &str = "mcp__papercraft__";
+
+pub fn parse_line(line: &str) -> Vec<Event> {
+    parse(line, false)
+}
+
+pub fn parse_line_partial(line: &str) -> Vec<Event> {
+    parse(line, true)
+}
+
+fn parse(line: &str, partial: bool) -> Vec<Event> {
+    let Ok(v) = serde_json::from_str::<Value>(line) else { return vec![] };
+    match v["type"].as_str() {
+        Some("system") if v["subtype"] == "init" => v["session_id"].as_str().map(|s| Event::Session(s.into())).into_iter().collect(),
+        Some("assistant") => assistant(&v, partial),
+        Some("user") => tool_results(&v),
+        Some("stream_event") if partial => delta(&v["event"]),
+        Some("result") => result(&v),
+        _ => vec![],
+    }
+}
+
+/// Tokens in the context at one model call: input plus cache, from an `assistant` line's
+/// `message.usage`. Sub-agent lines (`parent_tool_use_id` set) count against their own context.
+pub fn context_of(line: &str) -> Option<u64> {
+    let v = serde_json::from_str::<Value>(line).ok()?;
+    if v["type"] != "assistant" || !v["parent_tool_use_id"].is_null() {
+        return None;
+    }
+    let u = &v["message"]["usage"];
+    u.is_object().then(|| ["input_tokens", "cache_read_input_tokens", "cache_creation_input_tokens"].iter().map(|k| u[*k].as_u64().unwrap_or(0)).sum())
+}
+
+fn blocks(v: &Value) -> &[Value] {
+    v["message"]["content"].as_array().map_or(&[], Vec::as_slice)
+}
+
+fn assistant(v: &Value, partial: bool) -> Vec<Event> {
+    let mut out = vec![];
+    for b in blocks(v) {
+        match b["type"].as_str() {
+            Some("text") if !partial => push_text(&mut out, b["text"].as_str(), false),
+            Some("thinking") if !partial => push_text(&mut out, b["thinking"].as_str(), true),
+            Some("tool_use") => {
+                let name = str_of(&b["name"]);
+                out.push(Event::ToolStart {
+                    id: str_of(&b["id"]),
+                    name: name.strip_prefix(MCP_PREFIX).map_or(name.clone(), str::to_string),
+                    args: b["input"].clone(),
+                });
+            }
+            _ => {}
+        }
+    }
+    out
+}
+
+fn push_text(out: &mut Vec<Event>, s: Option<&str>, thinking: bool) {
+    let Some(s) = s.filter(|s| !s.is_empty()) else { return };
+    out.push(if thinking { Event::Thinking(s.into()) } else { Event::Text(s.into()) });
+}
+
+fn delta(e: &Value) -> Vec<Event> {
+    let mut out = vec![];
+    if e["type"] != "content_block_delta" {
+        return out;
+    }
+    let d = &e["delta"];
+    match d["type"].as_str() {
+        Some("text_delta") => push_text(&mut out, d["text"].as_str(), false),
+        Some("thinking_delta") => push_text(&mut out, d["thinking"].as_str(), true),
+        _ => {}
+    }
+    out
+}
+
+fn tool_results(v: &Value) -> Vec<Event> {
+    blocks(v)
+        .iter()
+        .filter(|b| b["type"] == "tool_result")
+        .map(|b| {
+            let id = str_of(&b["tool_use_id"]);
+            if b["is_error"].as_bool() == Some(true) {
+                Event::ToolEnd { id, result: None, error: Some(content_text(&b["content"])) }
+            } else {
+                Event::ToolEnd { id, result: Some(b["content"].clone()), error: None }
+            }
+        })
+        .collect()
+}
+
+fn result(v: &Value) -> Vec<Event> {
+    let mut out = vec![];
+    if v["is_error"].as_bool() == Some(true) {
+        let msg = v["result"].as_str().filter(|s| !s.is_empty()).unwrap_or("Claude Code reported an error");
+        out.push(Event::Error(msg.into()));
+    }
+    let u = &v["usage"];
+    let usage = u.is_object().then(|| Usage {
+        input: u["input_tokens"].as_u64().unwrap_or(0),
+        output: u["output_tokens"].as_u64().unwrap_or(0),
+        cache_read: u["cache_read_input_tokens"].as_u64().unwrap_or(0),
+        cache_write: u["cache_creation_input_tokens"].as_u64().unwrap_or(0),
+        cost_usd: v["total_cost_usd"].as_f64(),
+    });
+    out.push(Event::TurnEnd {
+        usage,
+        session: v["session_id"].as_str().map(Into::into),
+        stop_reason: v["stop_reason"].as_str().map(Into::into),
+    });
+    out
+}
+
+#[cfg(not(target_arch = "wasm32"))]
+pub use process::{args, detect, start};
+
+#[cfg(not(target_arch = "wasm32"))]
+mod process {
+    use super::*;
+    use crate::chat::events::{Turn, TurnConfig};
+    use std::collections::HashSet;
+    use std::io::{BufRead, BufReader, Read, Write};
+    use std::path::{Path, PathBuf};
+    use std::process::{Child, Command, Stdio};
+    use std::sync::atomic::{AtomicBool, Ordering};
+    use std::sync::{mpsc::Sender, Arc, Mutex};
+    use std::time::{Duration, Instant};
+
+    const STOP_GRACE: Duration = Duration::from_secs(3);
+    const STOP_POLL: Duration = Duration::from_millis(50);
+    /// Internal tool lookup the CLI does before calling a deferred MCP tool; not worth a card.
+    const HIDDEN_TOOL: &str = "ToolSearch";
+
+    /// The `claude` binary (override, else first on PATH) and its version, e.g. `2.1.306`.
+    pub fn detect(binary: Option<&Path>) -> Option<(PathBuf, String)> {
+        let path = match binary {
+            Some(p) => p.to_path_buf(),
+            None => crate::chat::path::which("claude")?,
+        };
+        let out = clean_env(&mut Command::new(&path)).arg("--version").output().ok().filter(|o| o.status.success())?;
+        let version = String::from_utf8_lossy(&out.stdout).split_whitespace().next()?.to_string();
+        Some((path, version))
+    }
+
+    /// `system_file` holds the system prompt (read by the CLI, so it is not in `ps` output).
+    pub fn args(cfg: &TurnConfig, system_file: Option<&Path>) -> Vec<String> {
+        let mcp = serde_json::json!({"mcpServers": {"papercraft": {"type": "http", "url": cfg.mcp_url}}});
+        let mut a: Vec<String> = [
+            "-p", "--input-format", "stream-json", "--output-format", "stream-json", "--verbose",
+            "--include-partial-messages", "--mcp-config", &mcp.to_string(), "--strict-mcp-config",
+            "--allowedTools", "mcp__papercraft__*",
+        ]
+        .map(String::from)
+        .into();
+        if let Some(f) = system_file {
+            a.extend(["--append-system-prompt-file".into(), f.display().to_string()]);
+        }
+        for (flag, v) in [("--model", &cfg.model), ("--effort", &cfg.effort), ("--resume", &cfg.session)] {
+            if let Some(v) = v {
+                a.extend([flag.into(), v.clone()]);
+            }
+        }
+        a
+    }
+
+    /// Keys that would make the CLI bill an API account instead of using its own login; the chat
+    /// must run on the user's CLI login (spec, Security), so they are never inherited.
+    const CREDENTIAL_ENV: [&str; 4] = ["ANTHROPIC_API_KEY", "ANTHROPIC_AUTH_TOKEN", "OPENAI_API_KEY", "CODEX_API_KEY"];
+
+    fn clean_env(cmd: &mut Command) -> &mut Command {
+        for k in CREDENTIAL_ENV {
+            cmd.env_remove(k);
+        }
+        crate::chat::path::apply(cmd)
+    }
+
+    /// Shared by the waiter thread and `stop`; only signalled while unreaped (`try_wait` is `None`),
+    /// and always reaped under the lock, so a recycled PID is never signalled.
+    struct Proc {
+        child: Arc<Mutex<Child>>,
+        running: Arc<AtomicBool>,
+        /// Set by `stop`: the exit that follows is the user's, not a failure.
+        stopped: Arc<AtomicBool>,
+    }
+
+    fn interrupt(child: &mut Child) {
+        #[cfg(unix)]
+        {
+            // SAFETY: plain syscall on the PID of a child that is still unreaped (caller holds the lock).
+            unsafe { libc::kill(child.id() as libc::pid_t, libc::SIGINT) };
+        }
+        #[cfg(not(unix))]
+        let _ = child.kill();
+    }
+
+    fn reap(mut child: Child) {
+        let _ = child.kill();
+        let _ = child.wait();
+    }
+
+    /// Off the UI thread: waits out the grace period, then kills and reaps a child that ignored SIGINT.
+    fn escalate(child: &Mutex<Child>) {
+        let t = Instant::now();
+        loop {
+            let mut c = child.lock().unwrap();
+            if !matches!(c.try_wait(), Ok(None)) {
+                return;
+            }
+            if t.elapsed() >= STOP_GRACE {
+                let _ = c.kill();
+                let _ = c.wait();
+                return;
+            }
+            drop(c);
+            std::thread::sleep(STOP_POLL);
+        }
+    }
+
+    impl Turn for Proc {
+        fn stop(&mut self) {
+            {
+                let mut c = self.child.lock().unwrap();
+                if !matches!(c.try_wait(), Ok(None)) {
+                    return;
+                }
+                self.stopped.store(true, Ordering::SeqCst);
+                interrupt(&mut c);
+            }
+            let child = self.child.clone();
+            std::thread::spawn(move || escalate(&child));
+        }
+        fn is_running(&self) -> bool {
+            self.running.load(Ordering::SeqCst)
+        }
+    }
+
+    /// The system prompt as a file under the project's tmp folder; the caller deletes it when the
+    /// turn is over.
+    fn write_system_file(cfg: &TurnConfig) -> Result<Option<PathBuf>, String> {
+        if cfg.system.is_empty() {
+            return Ok(None);
+        }
+        let dir = cfg.project_dir.join(crate::chat::TMP_DIR);
+        let file = dir.join(format!("system-{:016x}.txt", fastrand::u64(..)));
+        std::fs::create_dir_all(&dir).and_then(|()| std::fs::write(&file, &cfg.system)).map_err(|e| format!("could not write the system prompt: {e}"))?;
+        Ok(Some(file))
+    }
+
+    pub fn start(cfg: &TurnConfig, prompt: &str, tx: Sender<Event>) -> Result<Box<dyn Turn>, String> {
+        let (bin, _) = detect(cfg.binary.as_deref()).ok_or("Claude Code (`claude`) was not found")?;
+        let system_file = write_system_file(cfg)?;
+        let removed = system_file.clone();
+        let cleanup = move || {
+            if let Some(f) = &removed {
+                let _ = std::fs::remove_file(f);
+            }
+        };
+        let mut child = clean_env(&mut Command::new(bin))
+            .args(args(cfg, system_file.as_deref()))
+            .current_dir(&cfg.project_dir)
+            .stdin(Stdio::piped())
+            .stdout(Stdio::piped())
+            .stderr(Stdio::piped())
+            .spawn()
+            .map_err(|e| {
+                cleanup();
+                format!("could not start claude: {e}")
+            })?;
+        let (Some(mut stdin), Some(stdout), Some(mut stderr)) = (child.stdin.take(), child.stdout.take(), child.stderr.take()) else {
+            reap(child);
+            cleanup();
+            return Err("could not open the claude pipes".into());
+        };
+        let msg = serde_json::json!({"type": "user", "message": {"role": "user", "content": [{"type": "text", "text": prompt}]}});
+        // Dropping stdin after the one message makes the CLI finish the turn and exit.
+        if let Err(e) = writeln!(stdin, "{msg}") {
+            drop(stdin);
+            reap(child);
+            cleanup();
+            return Err(format!("could not send the message: {e}"));
+        }
+        drop(stdin);
+        let err_thread = std::thread::spawn(move || {
+            let mut s = String::new();
+            let _ = stderr.read_to_string(&mut s);
+            s
+        });
+        let running = Arc::new(AtomicBool::new(true));
+        let child = Arc::new(Mutex::new(child));
+        let stopped = Arc::new(AtomicBool::new(false));
+        let turn = Proc { child: child.clone(), running: running.clone(), stopped: stopped.clone() };
+        std::thread::spawn(move || {
+            let (mut ended, mut hidden) = (false, HashSet::new());
+            for line in BufReader::new(stdout).lines().map_while(Result::ok) {
+                if let Some(n) = context_of(&line) {
+                    let _ = tx.send(Event::Context(n));
+                }
+                for ev in parse_line_partial(&line) {
+                    match &ev {
+                        Event::ToolStart { id, name, .. } if name == HIDDEN_TOOL => {
+                            hidden.insert(id.clone());
+                            continue;
+                        }
+                        Event::ToolEnd { id, .. } if hidden.contains(id) => continue,
+                        Event::TurnEnd { .. } | Event::Error(_) => ended = true,
+                        _ => {}
+                    }
+                    let _ = tx.send(ev);
+                }
+            }
+            // Poll under the lock (never block in `wait` holding it) so `stop` can still signal.
+            let status = loop {
+                let r = child.lock().unwrap().try_wait();
+                match r {
+                    Ok(None) => std::thread::sleep(STOP_POLL),
+                    r => break r,
+                }
+            };
+            let stderr = err_thread.join().unwrap_or_default();
+            cleanup();
+            if !ended {
+                let ok = status.as_ref().is_ok_and(|s| s.as_ref().is_some_and(|s| s.success()));
+                let ev = if ok || stopped.load(Ordering::SeqCst) {
+                    Event::TurnEnd { usage: None, session: None, stop_reason: Some("stopped".into()).filter(|_| !ok) }
+                } else {
+                    let msg = stderr.trim();
+                    Event::Error(if msg.is_empty() { format!("claude exited: {status:?}") } else { msg.into() })
+                };
+                let _ = tx.send(ev);
+            }
+            running.store(false, Ordering::SeqCst);
+        });
+        Ok(Box::new(turn))
+    }
+
+    #[cfg(test)]
+    mod tests {
+        use super::*;
+        use std::sync::mpsc::channel;
+
+        #[test]
+        fn args_shape() {
+            let cfg = TurnConfig {
+                mcp_url: "http://127.0.0.1:1/mcp".into(),
+                system: "SYS".into(),
+                model: Some("m".into()),
+                session: Some("sid".into()),
+                ..Default::default()
+            };
+            let a = args(&cfg, Some(Path::new("/tmp/sys.txt")));
+            let at = |f: &str| a[a.iter().position(|x| x == f).unwrap() + 1].as_str();
+            assert_eq!(at("--output-format"), "stream-json");
+            assert_eq!(at("--allowedTools"), "mcp__papercraft__*");
+            assert_eq!(at("--append-system-prompt-file"), "/tmp/sys.txt");
+            assert!(!a.iter().any(|x| x == "SYS" || x == "--append-system-prompt"), "the prompt text is not in argv");
+            assert_eq!(at("--model"), "m");
+            assert_eq!(at("--resume"), "sid");
+            assert!(!a.contains(&"--effort".to_string()));
+            let mcp: Value = serde_json::from_str(at("--mcp-config")).unwrap();
+            assert_eq!(mcp["mcpServers"]["papercraft"]["url"], "http://127.0.0.1:1/mcp");
+            assert!(a.contains(&"--strict-mcp-config".to_string()));
+        }
+
+        #[test]
+        fn credentials_are_not_inherited() {
+            let mut c = Command::new("x");
+            clean_env(&mut c);
+            let removed: Vec<_> = c.get_envs().filter(|(_, v)| v.is_none()).map(|(k, _)| k.to_string_lossy().into_owned()).collect();
+            for k in CREDENTIAL_ENV {
+                assert!(removed.iter().any(|r| r == k), "{k}");
+            }
+        }
+
+        #[cfg(unix)]
+        fn fake_cli(name: &str, body: &str) -> PathBuf {
+            use std::os::unix::fs::PermissionsExt;
+            let p = std::env::temp_dir().join(format!("papercraft-fake-claude-{}-{name}", std::process::id()));
+            std::fs::write(&p, format!("#!/bin/sh\n[ \"$1\" = --version ] && {{ echo 1.0; exit 0; }}\n{body}\n")).unwrap();
+            std::fs::set_permissions(&p, std::fs::Permissions::from_mode(0o755)).unwrap();
+            p
+        }
+
+        #[cfg(unix)]
+        #[test]
+        fn stop_interrupts_and_reaps() {
+            let cfg = TurnConfig { binary: Some(fake_cli("stop", "exec sleep 30")), project_dir: std::env::temp_dir(), ..Default::default() };
+            let (tx, rx) = channel();
+            let mut turn = start(&cfg, "hi", tx).unwrap();
+            let t = Instant::now();
+            turn.stop();
+            assert!(t.elapsed() < Duration::from_millis(200), "stop blocked for {:?}", t.elapsed());
+            // A stop is the user's choice: it ends the turn, it is not an error.
+            assert!(matches!(rx.recv_timeout(Duration::from_secs(5)), Ok(Event::TurnEnd { stop_reason: Some(r), .. }) if r == "stopped"));
+            let t = Instant::now();
+            while turn.is_running() && t.elapsed() < Duration::from_secs(5) {
+                std::thread::sleep(Duration::from_millis(20));
+            }
+            assert!(!turn.is_running());
+            turn.stop(); // after the reap: must be a no-op
+        }
+
+        /// SIGINT is ignored, so the waiter thread must kill the child after the grace period.
+        #[cfg(unix)]
+        #[test]
+        fn stop_kills_a_child_that_ignores_sigint() {
+            let ready = std::env::temp_dir().join(format!("papercraft-stop-ready-{}", std::process::id()));
+            let body = format!("trap '' INT; touch '{}'; exec sleep 30", ready.display());
+            let cfg = TurnConfig { binary: Some(fake_cli("ignore", &body)), project_dir: std::env::temp_dir(), ..Default::default() };
+            let (tx, rx) = channel();
+            let mut turn = start(&cfg, "hi", tx).unwrap();
+            let t = Instant::now();
+            while !ready.exists() && t.elapsed() < Duration::from_secs(5) {
+                std::thread::sleep(Duration::from_millis(20));
+            }
+            turn.stop();
+            assert!(matches!(rx.recv_timeout(Duration::from_secs(8)), Ok(Event::TurnEnd { stop_reason: Some(r), .. }) if r == "stopped"));
+            assert!(!turn.is_running());
+            std::fs::remove_file(ready).ok();
+        }
+
+        /// The system prompt travels in a file under the project's tmp folder, never in argv, and
+        /// the file is gone when the turn is over.
+        #[cfg(unix)]
+        #[test]
+        fn system_prompt_goes_through_a_file_that_is_removed_afterwards() {
+            let dir = std::env::temp_dir().join(format!("papercraft-claude-sys-{}", std::process::id()));
+            std::fs::create_dir_all(&dir).unwrap();
+            let body = r#"for a; do [ "$a" = SECRET-PROMPT ] && exit 3; done; cat >/dev/null; echo '{"type":"result","session_id":"s"}'"#;
+            let cfg = TurnConfig { binary: Some(fake_cli("sysfile", body)), project_dir: dir.clone(), system: "SECRET-PROMPT".into(), ..Default::default() };
+            let (tx, rx) = channel();
+            let turn = start(&cfg, "hi", tx).unwrap();
+            let ev = rx.recv_timeout(Duration::from_secs(5)).unwrap();
+            assert!(matches!(ev, Event::TurnEnd { .. }), "{ev:?}");
+            let t = Instant::now();
+            while turn.is_running() && t.elapsed() < Duration::from_secs(5) {
+                std::thread::sleep(Duration::from_millis(20));
+            }
+            let left: Vec<_> = std::fs::read_dir(dir.join(crate::chat::TMP_DIR)).unwrap().flatten().collect();
+            assert!(left.is_empty(), "{left:?}");
+            std::fs::remove_dir_all(dir).ok();
+        }
+
+        #[cfg(unix)]
+        #[test]
+        fn failed_stdin_write_reaps_child() {
+            // Exits at once without reading; the large prompt overflows the pipe and fails the write.
+            let cfg = TurnConfig { binary: Some(fake_cli("nostdin", "exit 0")), project_dir: std::env::temp_dir(), ..Default::default() };
+            let (tx, _rx) = channel();
+            let big = "x".repeat(1 << 20);
+            assert!(start(&cfg, &big, tx).is_err());
+        }
+
+        /// Needs `claude` on PATH and PAPERCRAFT_TEST_CLAUDE=1; launches its own app instance.
+        #[test]
+        fn end_to_end() {
+            if std::env::var("PAPERCRAFT_TEST_CLAUDE").as_deref() != Ok("1") || detect(None).is_none() {
+                return;
+            }
+            let home = std::env::temp_dir().join(format!("papercraft-chat-e2e-{}", std::process::id()));
+            std::fs::create_dir_all(&home).unwrap();
+            let exe = Path::new(env!("CARGO_MANIFEST_DIR")).join("target/debug/papercraft");
+            let mut app = Command::new(exe)
+                .env("PAPERCRAFT_HOME", &home)
+                .env("PAPERCRAFT_MCP_PORT", "29984")
+                .stdout(Stdio::null())
+                .stderr(Stdio::null())
+                .spawn()
+                .expect("build target/debug/papercraft first");
+            std::thread::sleep(Duration::from_secs(4));
+            let cfg = TurnConfig {
+                project_dir: home.clone(),
+                mcp_url: "http://127.0.0.1:29984/mcp".into(),
+                ..Default::default()
+            };
+            let (tx, rx) = channel();
+            let r = start(&cfg, "Create a project named T via create_file, open it, then call get_basic_info", tx);
+            let mut ev = vec![];
+            if r.is_ok() {
+                while let Ok(e) = rx.recv_timeout(Duration::from_secs(240)) {
+                    let done = matches!(e, Event::TurnEnd { .. } | Event::Error(_));
+                    ev.push(e);
+                    if done {
+                        break;
+                    }
+                }
+            }
+            let _ = app.kill();
+            let _ = app.wait();
+            let _ = std::fs::remove_dir_all(&home);
+            r.map(|_| ()).unwrap();
+            assert!(matches!(ev.first(), Some(Event::Session(_))), "{ev:?}");
+            assert!(ev.iter().any(|e| matches!(e, Event::ToolStart { name, .. } if name == "get_basic_info")), "{ev:?}");
+            assert!(ev.iter().any(|e| matches!(e, Event::ToolEnd { .. })), "{ev:?}");
+            assert!(matches!(ev.last(), Some(Event::TurnEnd { .. })), "{ev:?}");
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use serde_json::json;
+
+    // Real recordings (claude 2.1, opus-5-5) with SessionStart hook lines, plugin/tool lists,
+    // paths and signatures stripped. The tool run used an own PaperCraft instance with no project
+    // open, so get_basic_info returns an error result.
+    const HI: &str = include_str!("../../tests/fixtures/chat/claude_code_hi.jsonl");
+    const TOOL: &str = include_str!("../../tests/fixtures/chat/claude_code_tool.jsonl");
+
+    fn all(f: &str, p: fn(&str) -> Vec<Event>) -> Vec<Event> {
+        f.lines().flat_map(p).collect()
+    }
+
+    #[test]
+    fn hi() {
+        let ev = all(HI, parse_line);
+        assert_eq!(ev.len(), 3);
+        assert!(matches!(&ev[0], Event::Session(s) if s.len() == 36));
+        assert_eq!(ev[1], Event::Text("Hi there, friend.".into()));
+        let Event::TurnEnd { usage: Some(u), session: Some(s), stop_reason } = &ev[2] else { panic!("{ev:?}") };
+        assert_eq!((u.input, u.output, u.cache_read, u.cache_write), (2, 10, 8857, 27039));
+        assert!(u.cost_usd.unwrap() > 0.0);
+        assert_eq!(s.len(), 36);
+        assert_eq!(stop_reason.as_deref(), Some("end_turn"));
+    }
+
+    #[test]
+    fn tool_run_whole_messages() {
+        let ev: Vec<Event> = all(TOOL, parse_line).into_iter().filter(|e| !matches!(e, Event::Session(_))).collect();
+        assert_eq!(ev.len(), 6, "{ev:?}");
+        let Event::ToolStart { name, args, .. } = &ev[0] else { panic!() };
+        assert_eq!((name.as_str(), args), ("ToolSearch", &json!({"query":"select:mcp__papercraft__get_basic_info","max_results":1})));
+        assert!(matches!(&ev[1], Event::ToolEnd { result: Some(_), error: None, .. }));
+        let Event::ToolStart { id, name, args } = &ev[2] else { panic!() };
+        assert_eq!((name.as_str(), args), ("get_basic_info", &json!({})));
+        let Event::ToolEnd { id: end_id, result: None, error: Some(e) } = &ev[3] else { panic!("{:?}", ev[3]) };
+        assert_eq!(end_id, id);
+        assert!(e.starts_with("No project is open"));
+        assert!(matches!(&ev[4], Event::Text(t) if t.contains("get_basic_info")));
+        assert!(matches!(&ev[5], Event::TurnEnd { stop_reason: Some(r), .. } if r == "end_turn"));
+    }
+
+    #[test]
+    fn partial_mode_streams_deltas_without_duplicates() {
+        let whole = all(TOOL, parse_line);
+        assert!(whole.iter().any(|e| matches!(e, Event::Session(_))));
+        let part = all(TOOL, parse_line_partial);
+        let text: String = part.iter().filter_map(|e| if let Event::Text(t) = e { Some(t.as_str()) } else { None }).collect();
+        let full: String = whole.iter().filter_map(|e| if let Event::Text(t) = e { Some(t.as_str()) } else { None }).collect();
+        assert_eq!(text, full);
+        assert!(part.iter().filter(|e| matches!(e, Event::Text(_))).count() > 1);
+        assert_eq!(part.iter().filter(|e| matches!(e, Event::ToolStart { .. })).count(), 2);
+    }
+
+    #[test]
+    fn context_is_the_last_calls_input_plus_cache_not_the_turn_total() {
+        let call = |input, read, write, parent: &str| {
+            format!(r#"{{"type":"assistant","parent_tool_use_id":{parent},"message":{{"content":[],"usage":{{"input_tokens":{input},"cache_read_input_tokens":{read},"cache_creation_input_tokens":{write},"output_tokens":9}}}}}}"#)
+        };
+        assert_eq!(context_of(&call(5, 1000, 200, "null")), Some(1205));
+        assert_eq!(context_of(&call(5, 1000, 200, r#""toolu_sub""#)), None, "a sub-agent has its own context");
+        assert_eq!(context_of(r#"{"type":"assistant","message":{"content":[]}}"#), None);
+        assert_eq!(context_of(r#"{"type":"result","usage":{"input_tokens":365000}}"#), None, "the result line sums the whole turn");
+        let from_fixture: Vec<u64> = TOOL.lines().filter_map(context_of).collect();
+        assert!(!from_fixture.is_empty());
+    }
+
+    #[test]
+    fn junk_and_errors() {
+        assert!(parse_line("not json").is_empty());
+        assert!(parse_line(r#"{"type":"rate_limit_event"}"#).is_empty());
+        let ev = parse_line(r#"{"type":"result","is_error":true,"result":"boom","session_id":"s"}"#);
+        assert_eq!(ev[0], Event::Error("boom".into()));
+        assert!(matches!(&ev[1], Event::TurnEnd { usage: None, session: Some(s), .. } if s == "s"));
+    }
+}
@@ -0,0 +1,431 @@
+//! Parser for `codex exec --json` JSONL events. Stateful only because the thread id arrives in
+//! `thread.started` and belongs on the `TurnEnd`.
+
+use super::events::{content_text, str_of, Event};
+use super::Usage;
+use serde_json::{json, Value};
+
+#[derive(Debug, Default)]
+pub struct Parser {
+    thread: Option<String>,
+}
+
+impl Parser {
+    pub fn parse_line(&mut self, line: &str) -> Vec<Event> {
+        let Ok(v) = serde_json::from_str::<Value>(line) else { return vec![] };
+        match v["type"].as_str() {
+            Some("thread.started") => {
+                self.thread = v["thread_id"].as_str().map(Into::into);
+                vec![]
+            }
+            Some("item.started") => item(&v["item"], false),
+            Some("item.completed") => item(&v["item"], true),
+            Some("turn.completed") => vec![Event::TurnEnd {
+                usage: usage(&v["usage"]),
+                session: self.thread.clone(),
+                stop_reason: None,
+            }],
+            Some("turn.failed") => vec![Event::Error(error_text(&v["error"], "turn failed"))],
+            Some("error") => vec![Event::Error(error_text(&v, "codex error"))],
+            _ => vec![],
+        }
+    }
+}
+
+fn error_text(v: &Value, fallback: &str) -> String {
+    let m = v["message"].as_str().or_else(|| v.as_str());
+    m.unwrap_or(fallback).into()
+}
+
+fn usage(u: &Value) -> Option<Usage> {
+    if !u.is_object() {
+        return None;
+    }
+    let get = |k: &str| u[k].as_u64().unwrap_or(0);
+    let cached = get("cached_input_tokens");
+    Some(Usage {
+        // Codex counts cached tokens inside input_tokens; Usage keeps them apart.
+        input: get("input_tokens").saturating_sub(cached),
+        output: get("output_tokens"),
+        cache_read: cached,
+        cache_write: get("cache_write_input_tokens"),
+        cost_usd: None,
+    })
+}
+
+fn item(i: &Value, done: bool) -> Vec<Event> {
+    let id = str_of(&i["id"]);
+    match (i["type"].as_str(), done) {
+        (Some("agent_message"), true) => text(i, false),
+        (Some("reasoning"), true) => text(i, true),
+        (Some("mcp_tool_call"), false) => {
+            vec![Event::ToolStart { id, name: str_of(&i["tool"]), args: i["arguments"].clone() }]
+        }
+        (Some("mcp_tool_call"), true) => {
+            let failed = i["status"] == "failed" || !i["error"].is_null();
+            let ev = if failed {
+                let msg = match &i["error"] {
+                    Value::Null => content_text(&i["result"]["content"]),
+                    e => error_text(e, "tool failed"),
+                };
+                Event::ToolEnd { id, result: None, error: Some(msg) }
+            } else {
+                Event::ToolEnd { id, result: Some(i["result"].clone()), error: None }
+            };
+            vec![ev]
+        }
+        (Some("command_execution"), false) => {
+            vec![Event::ToolStart { id, name: "command".into(), args: json!({ "command": i["command"] }) }]
+        }
+        (Some("command_execution"), true) => {
+            let ok = i["exit_code"].as_i64() == Some(0);
+            let out = str_of(&i["aggregated_output"]);
+            vec![if ok {
+                Event::ToolEnd { id, result: Some(json!(out)), error: None }
+            } else {
+                Event::ToolEnd { id, result: None, error: Some(out) }
+            }]
+        }
+        (Some("error"), true) => vec![Event::Error(error_text(i, "codex error"))],
+        _ => vec![],
+    }
+}
+
+fn text(i: &Value, thinking: bool) -> Vec<Event> {
+    let Some(t) = i["text"].as_str().filter(|t| !t.is_empty()) else { return vec![] };
+    vec![if thinking { Event::Thinking(t.into()) } else { Event::Text(t.into()) }]
+}
+
+#[cfg(not(target_arch = "wasm32"))]
+pub use process::{detect, start};
+#[cfg(all(test, not(target_arch = "wasm32")))]
+use process::build_args;
+
+#[cfg(not(target_arch = "wasm32"))]
+mod process {
+    use super::*;
+    use super::super::events::{Turn, TurnConfig};
+    use std::{ffi::OsString, io::{BufRead, BufReader, Read}, path::{Path, PathBuf},
+        process::{Child, Command, Stdio}, sync::{Arc, Mutex, atomic::{AtomicBool, Ordering}, mpsc::Sender},
+        thread, time::{Duration, Instant}};
+
+    /// Keys that would make the CLI bill an API account instead of using its own login; the chat
+    /// must run on the user's CLI login (spec, Security), so they are never inherited.
+    const CREDENTIAL_ENV: [&str; 4] = ["ANTHROPIC_API_KEY", "ANTHROPIC_AUTH_TOKEN", "OPENAI_API_KEY", "CODEX_API_KEY"];
+
+    pub(super) fn clean_env(cmd: &mut Command) -> &mut Command {
+        for k in CREDENTIAL_ENV { cmd.env_remove(k); }
+        crate::chat::path::apply(cmd)
+    }
+
+    pub fn detect(binary: Option<&Path>) -> Option<(PathBuf, String)> {
+        let path = match binary {
+            Some(path) => path.to_path_buf(),
+            None => crate::chat::path::which("codex")?,
+        };
+        Some(path).and_then(|path| {
+            let output = clean_env(&mut Command::new(&path)).arg("--version").output().ok()?;
+            if !output.status.success() { return None; }
+            let version = String::from_utf8(output.stdout).ok()?.trim().to_owned();
+            if version.is_empty() { return None; }
+            Some((path, version))
+        })
+    }
+
+    pub(super) fn build_args(cfg: &TurnConfig, prompt: &str) -> Vec<OsString> {
+        let mut args: Vec<OsString> = vec!["exec".into(), "--json".into(),
+            "--skip-git-repo-check".into(), "-C".into(), cfg.project_dir.as_os_str().into(),
+            "-c".into(), format!("mcp_servers.papercraft.url={}", json!(cfg.mcp_url)).into(),
+            // `exec` never asks, so a tool that needs approval is refused: pre-approve ours only.
+            "-c".into(), "mcp_servers.papercraft.default_tools_approval_mode=\"approve\"".into()];
+        if let Some(model) = &cfg.model { args.extend(["-m".into(), model.into()]); }
+        if let Some(session) = &cfg.session {
+            args.extend(["resume".into(), "--".into(), session.into(), prompt.into()]);
+        } else {
+            let prompt = if cfg.system.is_empty() { prompt.to_owned() }
+                else { format!("{}\n\n{prompt}", cfg.system) };
+            args.extend(["--".into(), prompt.into()]);
+        }
+        args
+    }
+
+    struct ProcessTurn {
+        child: Arc<Mutex<Child>>,
+        running: Arc<AtomicBool>,
+        /// Set by `stop`: the exit that follows is the user's, not a failure.
+        stopped: Arc<AtomicBool>,
+    }
+
+    impl Turn for ProcessTurn {
+        fn stop(&mut self) {
+            const STOP_TIMEOUT: Duration = Duration::from_secs(3);
+            const POLL: Duration = Duration::from_millis(20);
+            {
+                let mut child = self.child.lock().unwrap();
+                if !matches!(child.try_wait(), Ok(None)) { return; }
+                self.stopped.store(true, Ordering::SeqCst);
+                #[cfg(unix)]
+                {
+                    // The child is unreaped while this lock is held, so its PID cannot be reused.
+                    unsafe { libc::kill(child.id() as libc::pid_t, libc::SIGINT); }
+                }
+                #[cfg(not(unix))]
+                { let _ = child.kill(); }
+            }
+            // Off the UI thread: kill and reap if the child is still running after the grace period.
+            // `running` stays set until the reader thread has sent the turn's last event.
+            let shared = self.child.clone();
+            thread::spawn(move || {
+                let deadline = Instant::now() + STOP_TIMEOUT;
+                loop {
+                    {
+                        let mut child = shared.lock().unwrap();
+                        if !matches!(child.try_wait(), Ok(None)) { break; }
+                        if Instant::now() >= deadline {
+                            let _ = child.kill();
+                            let _ = child.wait();
+                            break;
+                        }
+                    }
+                    thread::sleep(POLL);
+                }
+            });
+        }
+
+        fn is_running(&self) -> bool { self.running.load(Ordering::Acquire) }
+    }
+
+    pub fn start(cfg: &TurnConfig, prompt: &str, tx: Sender<Event>) -> Result<Box<dyn Turn>, String> {
+        let bin = cfg.binary.clone().or_else(|| crate::chat::path::which("codex")).ok_or("Codex (`codex`) was not found")?;
+        let mut command = Command::new(bin);
+        clean_env(&mut command).args(build_args(cfg, prompt)).current_dir(&cfg.project_dir);
+        spawn_turn(command, tx)
+    }
+
+    pub(super) fn spawn_turn(mut command: Command, tx: Sender<Event>) -> Result<Box<dyn Turn>, String> {
+        let mut child = command.stdin(Stdio::null()).stdout(Stdio::piped()).stderr(Stdio::piped())
+            .spawn().map_err(|e| format!("Could not start Codex: {e}"))?;
+        let stdout = child.stdout.take().unwrap();
+        let mut stderr = child.stderr.take().unwrap();
+        let child = Arc::new(Mutex::new(child));
+        let running = Arc::new(AtomicBool::new(true));
+        let stopped = Arc::new(AtomicBool::new(false));
+        let turn = ProcessTurn { child: child.clone(), running: running.clone(), stopped: stopped.clone() };
+        thread::spawn(move || {
+            let stderr = thread::spawn(move || {
+                let mut text = String::new();
+                stderr.read_to_string(&mut text).map(|_| text)
+            });
+            let mut parser = Parser::default();
+            let mut terminal = None;
+            for line in BufReader::new(stdout).lines() {
+                let line = match line {
+                    Ok(line) => line,
+                    Err(e) => { terminal = Some(Event::Error(format!("Codex stdout: {e}"))); break; }
+                };
+                let previous = parser.thread.clone();
+                let events = parser.parse_line(&line);
+                if parser.thread != previous {
+                    if let Some(id) = &parser.thread { let _ = tx.send(Event::Session(id.clone())); }
+                }
+                for event in events {
+                    if matches!(event, Event::TurnEnd { .. } | Event::Error(_)) {
+                        terminal = Some(event);
+                    } else { let _ = tx.send(event); }
+                }
+            }
+            let status = loop {
+                let result = child.lock().unwrap().try_wait();
+                match result {
+                    Ok(None) => thread::sleep(Duration::from_millis(20)),
+                    result => break result,
+                }
+            };
+            let stderr = stderr.join().ok().and_then(Result::ok).unwrap_or_default();
+            let end = match status {
+                _ if stopped.load(Ordering::SeqCst) && !matches!(terminal, Some(Event::TurnEnd { .. })) =>
+                    Event::TurnEnd { usage: None, session: parser.thread.clone(), stop_reason: Some("stopped".into()) },
+                Ok(Some(status)) if status.success() => terminal.unwrap_or_else(||
+                    Event::Error("Codex exited without a turn result".into())),
+                Ok(Some(status)) => Event::Error(format!("Codex exited with {status}: {}", stderr.trim())),
+                Err(e) => Event::Error(format!("Could not wait for Codex: {e}")),
+                Ok(None) => unreachable!(),
+            };
+            // Send first: the app treats "not running" as "everything is in the channel".
+            let _ = tx.send(end);
+            running.store(false, Ordering::Release);
+        });
+        Ok(Box::new(turn))
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[cfg(not(target_arch = "wasm32"))]
+    #[test]
+    fn arguments_initial_and_resume() {
+        let mut cfg = super::super::events::TurnConfig {
+            project_dir: "/tmp/project space".into(),
+            mcp_url: "http://127.0.0.1:29980/mcp".into(),
+            system: "PaperCraft instructions".into(),
+            model: Some("test-model".into()),
+            ..Default::default()
+        };
+        let args = build_args(&cfg, "-prompt");
+        assert_eq!(args, vec!["exec", "--json", "--skip-git-repo-check", "-C",
+            "/tmp/project space", "-c", "mcp_servers.papercraft.url=\"http://127.0.0.1:29980/mcp\"",
+            "-c", "mcp_servers.papercraft.default_tools_approval_mode=\"approve\"",
+            "-m", "test-model", "--", "PaperCraft instructions\n\n-prompt"]);
+        cfg.session = Some("session-id".into());
+        let args = build_args(&cfg, "next");
+        assert_eq!(&args[args.len() - 4..], ["resume", "--", "session-id", "next"].map(std::ffi::OsString::from));
+    }
+
+    #[cfg(not(target_arch = "wasm32"))]
+    #[test]
+    fn credentials_are_not_inherited() {
+        let mut c = std::process::Command::new("x");
+        process::clean_env(&mut c);
+        let removed: Vec<_> = c.get_envs().filter(|(_, v)| v.is_none()).map(|(k, _)| k.to_string_lossy().into_owned()).collect();
+        for k in ["ANTHROPIC_API_KEY", "ANTHROPIC_AUTH_TOKEN", "OPENAI_API_KEY", "CODEX_API_KEY"] {
+            assert!(removed.iter().any(|r| r == k), "{k}");
+        }
+    }
+
+    #[cfg(unix)]
+    #[test]
+    fn stop_interrupts_and_reaps() {
+        let mut cmd = std::process::Command::new("sleep");
+        cmd.arg("30");
+        let (tx, rx) = std::sync::mpsc::channel();
+        let mut turn = process::spawn_turn(cmd, tx).unwrap();
+        let t = std::time::Instant::now();
+        turn.stop();
+        assert!(t.elapsed() < std::time::Duration::from_millis(200), "stop blocked for {:?}", t.elapsed());
+        // A stop is the user's choice: it ends the turn, it is not an error.
+        assert!(matches!(rx.recv_timeout(std::time::Duration::from_secs(5)), Ok(Event::TurnEnd { stop_reason: Some(r), .. }) if r == "stopped"));
+        turn.stop(); // already reaped: no-op
+    }
+
+    #[cfg(not(target_arch = "wasm32"))]
+    #[test]
+    fn codex_integration() {
+        if std::env::var("PAPERCRAFT_TEST_CODEX").as_deref() != Ok("1") || detect(None).is_none() {
+            return;
+        }
+        let cfg = super::super::events::TurnConfig {
+            project_dir: std::env::temp_dir(),
+            mcp_url: "http://127.0.0.1:9/mcp".into(),
+            ..Default::default()
+        };
+        let (tx, rx) = std::sync::mpsc::channel();
+        let mut turn = start(&cfg, "Reply with exactly: hello. Do not use tools.", tx).unwrap();
+        let deadline = std::time::Instant::now() + std::time::Duration::from_secs(90);
+        let mut session = false;
+        let mut text = false;
+        loop {
+            let remaining = deadline.saturating_duration_since(std::time::Instant::now());
+            match rx.recv_timeout(remaining) {
+                Ok(Event::Session(_)) => session = true,
+                Ok(Event::Text(_)) => text = true,
+                Ok(Event::TurnEnd { .. }) => break,
+                Ok(Event::Error(e)) => panic!("{e}"),
+                Ok(_) => {},
+                Err(e) => { turn.stop(); panic!("Codex timed out: {e}"); }
+            }
+        }
+        assert!(session && text);
+        assert!(!turn.is_running());
+    }
+
+    #[cfg(unix)]
+    #[test]
+    fn process_events_exit_and_stop() {
+        use std::time::Duration;
+        fn launch(body: &str, tx: std::sync::mpsc::Sender<Event>) -> Box<dyn super::super::events::Turn> {
+            let mut command = std::process::Command::new("/bin/sh");
+            command.args(["-c", body]);
+            process::spawn_turn(command, tx).unwrap()
+        }
+        for (body, fails) in [
+            (format!("printf '%s\\n' '{}'", HI.trim().replace('\n', "' '")), false),
+            ("printf '%s\\n' '{\"type\":\"thread.started\",\"thread_id\":\"early\"}'; echo diagnostic >&2; exit 7".into(), true),
+        ] {
+            let (tx, rx) = std::sync::mpsc::channel();
+            let turn = launch(&body, tx);
+            assert!(matches!(rx.recv_timeout(Duration::from_secs(5)).unwrap(), Event::Session(_)));
+            let events: Vec<_> = rx.iter().collect();
+            if fails {
+                assert!(matches!(events.last(), Some(Event::Error(e)) if e.contains("diagnostic")));
+            } else {
+                assert!(events.iter().any(|e| matches!(e, Event::Text(_))));
+                assert!(matches!(events.last(), Some(Event::TurnEnd { .. })));
+            }
+            assert!(!turn.is_running());
+        }
+        let (tx, rx) = std::sync::mpsc::channel();
+        let mut turn = launch("trap '' INT; printf '%s\\n' '{\"type\":\"thread.started\",\"thread_id\":\"stop\"}'; while :; do :; done", tx);
+        assert!(matches!(rx.recv_timeout(Duration::from_secs(5)).unwrap(), Event::Session(_)));
+        assert!(turn.is_running());
+        let before = std::time::Instant::now();
+        turn.stop();
+        assert!(before.elapsed() < Duration::from_secs(4));
+        // The user's stop ends the turn, it is not an error; "not running" comes after that event.
+        assert!(matches!(rx.recv_timeout(Duration::from_secs(5)).unwrap(), Event::TurnEnd { stop_reason: Some(r), .. } if r == "stopped"));
+        let t = std::time::Instant::now();
+        while turn.is_running() && t.elapsed() < Duration::from_secs(5) {
+            std::thread::sleep(Duration::from_millis(20));
+        }
+        assert!(!turn.is_running());
+    }
+
+    // Real recordings from codex exec --json (--ephemeral, scratch dir, own PaperCraft instance
+    // with no project open). codex_synthetic.jsonl is SYNTHETIC, written from the documented event
+    // shapes to cover reasoning, command_execution, error and turn.failed.
+    const HI: &str = include_str!("../../tests/fixtures/chat/codex_hi.jsonl");
+    const TOOL: &str = include_str!("../../tests/fixtures/chat/codex_tool.jsonl");
+    const SYNTH: &str = include_str!("../../tests/fixtures/chat/codex_synthetic.jsonl");
+
+    fn all(f: &str) -> Vec<Event> {
+        let mut p = Parser::default();
+        f.lines().flat_map(|l| p.parse_line(l)).collect()
+    }
+
+    #[test]
+    fn hi() {
+        let ev = all(HI);
+        assert_eq!(ev[0], Event::Text("Hi there, friend!".into()));
+        let Event::TurnEnd { usage: Some(u), session: Some(s), .. } = &ev[1] else { panic!("{ev:?}") };
+        assert_eq!((u.input, u.output, u.cache_read, u.cache_write), (26064 - 12288, 9, 12288, 0));
+        assert_eq!(s, "01a16076-15a4-71c0-8cfa-df664e87bdd2");
+        assert_eq!(ev.len(), 2);
+    }
+
+    #[test]
+    fn tool_run() {
+        let ev = all(TOOL);
+        assert_eq!(ev.len(), 5, "{ev:?}");
+        assert!(matches!(&ev[0], Event::Text(_)));
+        let Event::ToolStart { id, name, args } = &ev[1] else { panic!() };
+        assert_eq!((id.as_str(), name.as_str(), args), ("item_1", "get_basic_info", &json!({})));
+        let Event::ToolEnd { id: e, result: None, error: Some(m) } = &ev[2] else { panic!("{:?}", ev[2]) };
+        assert_eq!(e, id);
+        assert!(m.starts_with("No project is open"));
+        assert_eq!(ev[3], Event::Text("No file open in PaperCraft.".into()));
+        assert!(matches!(&ev[4], Event::TurnEnd { session: Some(_), .. }));
+    }
+
+    #[test]
+    fn synthetic() {
+        let ev = all(SYNTH);
+        assert_eq!(ev[0], Event::Thinking("Plan the frame first.".into()));
+        assert!(matches!(&ev[1], Event::ToolStart { name, .. } if name == "command"));
+        assert!(matches!(&ev[2], Event::ToolEnd { result: Some(r), .. } if r == "a.txt\n"));
+        assert!(matches!(&ev[3], Event::ToolStart { name, args, .. } if name == "create_artboard" && args["name"] == "Home"));
+        assert!(matches!(&ev[4], Event::ToolEnd { error: Some(e), .. } if e == "denied"));
+        assert_eq!(ev[5], Event::Error("stream disconnected, retrying".into()));
+        assert_eq!(ev[6], Event::Error("rate limited".into()));
+    }
+}
@@ -0,0 +1,226 @@
+//! API endpoints for the chat API backend: a name, a wire format, a base URL and a model. Keys
+//! live in the OS keychain under the endpoint's base URL, never in settings files.
+
+use serde::{Deserialize, Serialize};
+
+pub const CLAUDE_HOST: &str = "api.anthropic.com";
+pub const DEFAULT_ENDPOINT_ID: &str = "anthropic";
+pub const DEFAULT_BASE_URL: &str = "https://api.anthropic.com";
+pub const DEFAULT_MODEL: &str = "claude-opus-5-5";
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Default, Serialize, Deserialize)]
+#[serde(rename_all = "snake_case")]
+pub enum ApiFormat {
+    /// Messages API: `POST {base}/v1/messages`, `x-api-key`.
+    #[default]
+    Anthropic,
+    /// Chat Completions: `POST {base}/chat/completions`, `Authorization: Bearer`.
+    OpenAi,
+}
+
+#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
+#[serde(default)]
+pub struct Endpoint {
+    pub id: String,
+    pub name: String,
+    pub format: ApiFormat,
+    pub base_url: String,
+    pub model: String,
+}
+
+/// The built-in `Anthropic` endpoint, so the first-run path stays one key away.
+impl Default for Endpoint {
+    fn default() -> Self {
+        Self {
+            id: DEFAULT_ENDPOINT_ID.into(),
+            name: "Anthropic".into(),
+            format: ApiFormat::Anthropic,
+            base_url: DEFAULT_BASE_URL.into(),
+            model: DEFAULT_MODEL.into(),
+        }
+    }
+}
+
+impl Endpoint {
+    /// A blank endpoint for the settings "Add" button.
+    pub fn blank() -> Self {
+        Self { id: format!("ep-{:08x}", fastrand::u32(..)), name: "New endpoint".into(), format: ApiFormat::OpenAi, base_url: String::new(), model: String::new() }
+    }
+
+    /// Claude-only request fields (effort, thinking display, fallbacks, eager input streaming,
+    /// cache breakpoints) are sent only to this host.
+    pub fn is_claude_host(&self) -> bool {
+        host(&self.base_url).as_deref() == Some(CLAUDE_HOST)
+    }
+
+    /// A chat can use it: URL and model are set.
+    pub fn is_complete(&self) -> bool {
+        !self.base_url.trim().is_empty() && !self.model.trim().is_empty()
+    }
+
+    /// `anthropic.com` needs a key; local and third-party servers may not.
+    pub fn needs_key(&self) -> bool {
+        self.is_claude_host()
+    }
+
+    pub fn url(&self) -> String {
+        let base = self.base_url.trim().trim_end_matches('/');
+        match self.format {
+            ApiFormat::Anthropic => format!("{base}/v1/messages"),
+            ApiFormat::OpenAi => format!("{base}/chat/completions"),
+        }
+    }
+}
+
+/// Trimmed, no trailing slash, scheme and host lowercased (the path keeps its case).
+pub fn normalize_url(url: &str) -> String {
+    let u = url.trim().trim_end_matches('/');
+    let Some((scheme, rest)) = u.split_once("://") else { return u.to_lowercase() };
+    let (authority, path) = rest.split_once('/').map_or((rest, ""), |(a, p)| (a, p));
+    let sep = if path.is_empty() { "" } else { "/" };
+    format!("{}://{}{sep}{path}", scheme.to_lowercase(), authority.to_lowercase())
+}
+
+/// Lowercase host without userinfo or port.
+pub fn host(url: &str) -> Option<String> {
+    let rest = url.trim().split_once("://")?.1;
+    let authority = rest.split(['/', '?', '#']).next()?;
+    let hostport = authority.rsplit('@').next()?;
+    let host = hostport.split(':').next()?.to_lowercase();
+    (!host.is_empty()).then_some(host)
+}
+
+/// Keychain user name for an endpoint's key.
+pub fn key_user(base_url: &str) -> String {
+    format!("api-key:{}", normalize_url(base_url))
+}
+
+#[cfg(not(target_arch = "wasm32"))]
+pub use keys::{delete_key, get_key, set_key};
+
+#[cfg(not(target_arch = "wasm32"))]
+mod keys {
+    use super::*;
+
+    const KEY_SERVICE: &str = "PaperCraft";
+    /// The entry used before endpoints existed; still read for `api.anthropic.com`.
+    const LEGACY_KEY_USER: &str = "anthropic-api-key";
+    const KEY_ENV: &str = "ANTHROPIC_API_KEY";
+
+    fn entry(user: &str) -> Result<keyring::Entry, String> {
+        keyring::Entry::new(KEY_SERVICE, user).map_err(|e| e.to_string())
+    }
+
+    fn read(user: &str) -> Option<String> {
+        entry(user).ok()?.get_password().ok().map(|k| k.trim().to_string()).filter(|k| !k.is_empty())
+    }
+
+    fn remove(user: &str) -> Result<(), String> {
+        match entry(user)?.delete_credential() {
+            Ok(()) | Err(keyring::Error::NoEntry) => Ok(()),
+            Err(e) => Err(e.to_string()),
+        }
+    }
+
+    /// The stored key, for `api.anthropic.com` also the legacy entry, then `ANTHROPIC_API_KEY`.
+    /// Never log the result.
+    pub fn get_key(ep: &Endpoint) -> Option<String> {
+        let stored = read(&key_user(&ep.base_url));
+        if !ep.is_claude_host() {
+            return stored;
+        }
+        stored.or_else(|| read(LEGACY_KEY_USER)).or_else(|| std::env::var(KEY_ENV).ok().map(|k| k.trim().to_string()).filter(|k| !k.is_empty()))
+    }
+
+    /// Saves under the endpoint's base URL; a legacy entry is dropped (the key moved).
+    pub fn set_key(ep: &Endpoint, key: &str) -> Result<(), String> {
+        entry(&key_user(&ep.base_url))?.set_password(key.trim()).map_err(|e| e.to_string())?;
+        if ep.is_claude_host() {
+            let _ = remove(LEGACY_KEY_USER);
+        }
+        Ok(())
+    }
+
+    pub fn delete_key(ep: &Endpoint) -> Result<(), String> {
+        remove(&key_user(&ep.base_url))?;
+        if ep.is_claude_host() {
+            remove(LEGACY_KEY_USER)?;
+        }
+        Ok(())
+    }
+}
+
+/// `(input, output)` USD per million tokens for models in the Claude price table; None for any
+/// other model (the cost line then shows tokens only).
+pub fn price(model: &str) -> Option<(f64, f64)> {
+    if !model.starts_with("claude") {
+        return None;
+    }
+    match model {
+        m if m.contains("haiku") => Some((0.10, 0.50)),
+        m if m.contains("sonnet") => Some((2.0, 10.0)),
+        m if m.contains("opus") => Some((4.0, 20.0)),
+        _ => None,
+    }
+}
+
+const TOKENS_PER_MTOK: f64 = 1_000_000.0;
+const CACHE_READ_FACTOR: f64 = 0.1;
+const CACHE_WRITE_FACTOR: f64 = 1.25;
+
+/// Estimated USD for `u` on `model` (cache reads at 10% of input, writes at 125%); None for a
+/// model without a price.
+pub fn cost(model: &str, u: &super::Usage) -> Option<f64> {
+    let (pin, pout) = price(model)?;
+    let input = u.input as f64 + u.cache_read as f64 * CACHE_READ_FACTOR + u.cache_write as f64 * CACHE_WRITE_FACTOR;
+    Some((input * pin + u.output as f64 * pout) / TOKENS_PER_MTOK)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn host_ignores_userinfo_port_and_lookalikes() {
+        for (url, h) in [
+            ("https://api.anthropic.com", Some("api.anthropic.com")),
+            ("HTTPS://API.Anthropic.com/v1/", Some("api.anthropic.com")),
+            ("https://api.anthropic.com:443/x", Some("api.anthropic.com")),
+            ("https://api.anthropic.com@evil.example/x", Some("evil.example")),
+            ("https://api.anthropic.com.evil.example", Some("api.anthropic.com.evil.example")),
+            ("http://127.0.0.1:11434/v1", Some("127.0.0.1")),
+            ("not a url", None),
+        ] {
+            assert_eq!(host(url).as_deref(), h, "{url}");
+        }
+        let claude = |u: &str| Endpoint { base_url: u.into(), ..Default::default() }.is_claude_host();
+        assert!(claude("https://api.anthropic.com/") && !claude("https://api.anthropic.com.evil.example") && !claude("http://127.0.0.1:1"));
+    }
+
+    #[test]
+    fn keyring_user_is_the_normalized_base_url() {
+        assert_eq!(key_user("https://api.anthropic.com"), "api-key:https://api.anthropic.com");
+        assert_eq!(key_user("  HTTPS://API.Anthropic.com/  "), "api-key:https://api.anthropic.com");
+        assert_eq!(key_user("http://127.0.0.1:11434/v1/"), "api-key:http://127.0.0.1:11434/v1");
+        assert_eq!(key_user("https://h.example/Path/X"), "api-key:https://h.example/Path/X");
+    }
+
+    #[test]
+    fn urls_per_format() {
+        let mut e = Endpoint { base_url: "https://h.example/anthropic/".into(), ..Default::default() };
+        assert_eq!(e.url(), "https://h.example/anthropic/v1/messages");
+        e.format = ApiFormat::OpenAi;
+        e.base_url = "http://127.0.0.1:11434/v1".into();
+        assert_eq!(e.url(), "http://127.0.0.1:11434/v1/chat/completions");
+    }
+
+    #[test]
+    fn price_only_for_claude_models() {
+        let u = crate::chat::Usage { input: 1_000_000, output: 1_000_000, cache_read: 1_000_000, cache_write: 0, cost_usd: None };
+        assert!((cost("claude-opus-5-5", &u).unwrap() - 24.4).abs() < 1e-9);
+        assert!((cost("claude-sonnet-5-5", &u).unwrap() - 12.2).abs() < 1e-9);
+        assert!((cost("claude-haiku-5-5", &u).unwrap() - 0.61).abs() < 1e-9);
+        assert_eq!(cost("MiniMax-M3.1-Flash", &u), None);
+        assert_eq!(cost("llama3", &u), None);
+    }
+}
@@ -0,0 +1,96 @@
+//! The one event stream every chat backend (Claude Code, Codex, API endpoints) is turned into.
+
+use super::Usage;
+use serde_json::Value;
+
+#[derive(Debug, Clone, PartialEq)]
+pub enum Event {
+    Text(String),
+    Thinking(String),
+    ToolStart { id: String, name: String, args: Value },
+    /// `result` on success, `error` on failure; exactly one is set.
+    ToolEnd { id: String, result: Option<Value>, error: Option<String> },
+    TurnEnd { usage: Option<Usage>, session: Option<String>, stop_reason: Option<String> },
+    /// The backend's session id, as soon as it is known (so a stopped turn can still resume).
+    Session(String),
+    /// API backend: a destructive tool waits for `ApiTurn::approve(id, ..)` before it runs.
+    NeedsApproval { id: String, name: String, args: Value },
+    Error(String),
+    /// Tokens in the context at the backend's latest model call (input and cache), not summed
+    /// over the turn: the header meter.
+    Context(u64),
+}
+
+/// Sends a tool call to the UI thread (the app's MCP dispatch), so runs, undo and the agent log
+/// behave exactly as for an MCP request. Returns false when the app no longer takes calls.
+#[cfg(not(target_arch = "wasm32"))]
+#[derive(Clone)]
+pub struct ToolDispatch(pub std::sync::Arc<dyn Fn(crate::mcp::Call) -> bool + Send + Sync>);
+
+#[cfg(not(target_arch = "wasm32"))]
+impl std::fmt::Debug for ToolDispatch {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        f.write_str("ToolDispatch")
+    }
+}
+
+/// An image the user attached to a message (API backend: sent as an image block).
+#[derive(Debug, Clone, PartialEq)]
+pub struct ImageAttachment {
+    /// `image/png`, `image/jpeg`, ...
+    pub mime: String,
+    pub data: Vec<u8>,
+}
+
+/// What a turn needs from the app, the same for every backend.
+#[derive(Debug, Clone, Default)]
+pub struct TurnConfig {
+    /// The project folder (working directory for CLI agents).
+    pub project_dir: std::path::PathBuf,
+    /// The app's MCP endpoint, `http://127.0.0.1:<port>/mcp`.
+    pub mcp_url: String,
+    /// PaperCraft skill text and project context, appended to the system prompt.
+    pub system: String,
+    /// Model id; None = the backend's default (API: the endpoint's model).
+    pub model: Option<String>,
+    /// `low` | `medium` | `high`; None = the backend's default.
+    pub effort: Option<String>,
+    /// Resume this backend session.
+    pub session: Option<String>,
+    /// Override for the CLI binary path.
+    pub binary: Option<std::path::PathBuf>,
+    /// API backend: where tool calls run (see [`ToolDispatch`]).
+    #[cfg(not(target_arch = "wasm32"))]
+    pub tools: Option<ToolDispatch>,
+    /// API backend: the raw messages array, `chats/<id>.api.json`.
+    pub api_history: Option<std::path::PathBuf>,
+    /// API backend: images attached to the new user message.
+    pub images: Vec<ImageAttachment>,
+    /// API backend: the endpoint (format, base URL, model).
+    pub endpoint: super::endpoint::Endpoint,
+    /// API backend: base URL override for the request only (tests); Claude-only fields still follow
+    /// `endpoint`. Anthropic format also reads `PAPERCRAFT_ANTHROPIC_BASE_URL`.
+    pub api_base_url: Option<String>,
+}
+
+/// A running turn. Events arrive on the receiver given to `start`; the last one is `TurnEnd`
+/// or `Error`.
+pub trait Turn: Send {
+    /// Ask the backend to stop; it must end within 3 s (kill after that).
+    fn stop(&mut self);
+    fn is_running(&self) -> bool;
+}
+
+/// Text of a tool result: a plain string, or the `text` of each content block joined.
+pub(crate) fn content_text(v: &Value) -> String {
+    match v {
+        Value::String(s) => s.clone(),
+        Value::Array(a) => a.iter().filter_map(|b| b["text"].as_str()).collect::<Vec<_>>().join("\n"),
+        Value::Null => String::new(),
+        other => other.to_string(),
+    }
+}
+
+pub(crate) fn str_of(v: &Value) -> String {
+    v.as_str().unwrap_or_default().to_string()
+}
@@ -0,0 +1,141 @@
+//! Chat: a conversation with a coding agent (Claude Code, Codex or an API endpoint). Each chat
+//! is one JSON file under the project's `chats/` folder, see [`store`].
+
+pub mod agents;
+#[cfg(not(target_arch = "wasm32"))]
+pub mod acp;
+pub mod anthropic;
+pub mod claude_code;
+pub mod codex;
+pub mod endpoint;
+pub mod events;
+#[cfg(not(target_arch = "wasm32"))]
+pub mod openai;
+#[cfg(not(target_arch = "wasm32"))]
+pub mod path;
+pub mod store;
+#[cfg(not(target_arch = "wasm32"))]
+pub mod tools;
+
+use serde::{Deserialize, Serialize};
+use serde_json::Value;
+
+/// Where images for CLI backends and the system prompt file are saved, under the project folder.
+pub const TMP_DIR: &str = ".papercraft-chat-tmp";
+/// Each agent's own setup page, linked from a missing agent's row.
+pub const CLAUDE_DOCS: &str = "https://docs.anthropic.com/en/docs/claude-code/setup";
+pub const CODEX_DOCS: &str = "https://github.com/openai/codex";
+const ID_MAX: usize = 64;
+
+/// Chat ids become file and folder names, so only ascii letters, digits, `-` and `_` pass: no
+/// path separators, no `.`.
+pub fn valid_id(id: &str) -> bool {
+    !id.is_empty() && id.len() <= ID_MAX && id.bytes().all(|b| b.is_ascii_alphanumeric() || b == b'-' || b == b'_')
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Default, Serialize, Deserialize)]
+#[serde(rename_all = "snake_case")]
+pub enum BackendKind {
+    #[default]
+    ClaudeCode,
+    Codex,
+    /// An API endpoint (any format); the name is kept for saved chats.
+    Anthropic,
+    /// Any agent that speaks the Agent Client Protocol; [`Backend::agent`] says which.
+    Acp,
+}
+
+#[derive(Debug, Clone, PartialEq, Eq, Default, Serialize, Deserialize)]
+pub struct Backend {
+    pub kind: BackendKind,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub model: Option<String>,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub effort: Option<String>,
+    /// API chats: the endpoint's id; None = the default endpoint.
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub endpoint: Option<String>,
+    /// The CLI's session id, so a follow-up message resumes the same session.
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub cli_session: Option<String>,
+    /// `Acp` chats: the registry id (`agents::AGENTS`) or custom agent id.
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub agent: Option<String>,
+}
+
+#[derive(Debug, Clone, PartialEq, Default, Serialize, Deserialize)]
+pub struct Usage {
+    #[serde(default)]
+    pub input: u64,
+    #[serde(default)]
+    pub output: u64,
+    #[serde(default)]
+    pub cache_read: u64,
+    #[serde(default)]
+    pub cache_write: u64,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub cost_usd: Option<f64>,
+}
+
+#[derive(Debug, Clone, PartialEq, Default, Serialize, Deserialize)]
+pub struct ToolCall {
+    #[serde(default)]
+    pub id: String,
+    #[serde(default)]
+    pub name: String,
+    #[serde(default)]
+    pub args: Value,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub result: Option<Value>,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub error: Option<String>,
+    /// Milliseconds the tool took.
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub ms: Option<u64>,
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Default, Serialize, Deserialize)]
+#[serde(rename_all = "lowercase")]
+pub enum Role {
+    #[default]
+    User,
+    Assistant,
+}
+
+#[derive(Debug, Clone, PartialEq, Default, Serialize, Deserialize)]
+pub struct Message {
+    #[serde(default)]
+    pub role: Role,
+    #[serde(default)]
+    pub text: String,
+    #[serde(default, skip_serializing_if = "Vec::is_empty")]
+    pub tools: Vec<ToolCall>,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub run_id: Option<String>,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub usage: Option<Usage>,
+    /// Tokens in the context at the turn's last model call (input and cache), for the header meter.
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub context: Option<u64>,
+    /// Unix milliseconds.
+    #[serde(default)]
+    pub at: u64,
+}
+
+#[derive(Debug, Clone, PartialEq, Default, Serialize, Deserialize)]
+pub struct Chat {
+    #[serde(default)]
+    pub id: String,
+    #[serde(default)]
+    pub title: String,
+    /// Unix milliseconds.
+    #[serde(default)]
+    pub created: u64,
+    /// Unix milliseconds; `list` sorts on it.
+    #[serde(default)]
+    pub updated: u64,
+    #[serde(default)]
+    pub backend: Backend,
+    #[serde(default)]
+    pub messages: Vec<Message>,
+}
@@ -0,0 +1,782 @@
+//! Chat Completions streaming (OpenAI-compatible endpoints): an SSE accumulator that turns the
+//! response into [`Event`]s, and the tool loop. Same event stream, approvals, schema validation,
+//! round cap and persist-then-emit rule as `anthropic`. No provider-specific request fields.
+//!
+//! History (`chats/<id>.api.json`) is the OpenAI `messages` array without the system message:
+//! `user`, `assistant` (with `tool_calls`) and `tool` messages. An OpenAI `tool` message carries
+//! text only, so a tool result with an image goes back as the text `[image omitted]` and the image
+//! follows as an extra `user` message right after the tool messages of that round.
+
+use super::events::Event;
+use super::{Usage, endpoint};
+use serde_json::{Value, json};
+use std::collections::BTreeMap;
+
+/// One tool call of a finished reply.
+#[derive(Debug, Clone, PartialEq)]
+pub struct ToolUse {
+    pub id: String,
+    pub name: String,
+    /// The parsed arguments, or why they could not be parsed.
+    pub input: Result<Value, String>,
+}
+
+#[derive(Debug, Default)]
+struct Call {
+    id: String,
+    name: String,
+    args: String,
+}
+
+#[derive(Debug, Default)]
+pub struct ChatParser {
+    buf: String,
+    text: String,
+    calls: BTreeMap<usize, Call>,
+    uses: Vec<ToolUse>,
+    ended: bool,
+    finish: Option<String>,
+    usage: Option<Usage>,
+    /// Prompt tokens of the call (input and cache), for the context meter.
+    prompt: u64,
+    done: bool,
+}
+
+impl ChatParser {
+    /// Feed any chunk of the response body; incomplete lines wait for the next call.
+    pub fn push(&mut self, chunk: &str) -> Vec<Event> {
+        self.buf.push_str(chunk);
+        let mut out = vec![];
+        while let Some(nl) = self.buf.find('\n') {
+            let line: String = self.buf.drain(..=nl).collect();
+            let Some(data) = line.trim_end().strip_prefix("data:") else { continue };
+            let data = data.trim();
+            if data == "[DONE]" {
+                self.done = true;
+                self.end_round(&mut out);
+            } else if let Ok(v) = serde_json::from_str::<Value>(data) {
+                self.chunk(&v, &mut out);
+            }
+        }
+        out
+    }
+
+    /// `[DONE]` seen: the reply is complete.
+    pub fn done(&self) -> bool {
+        self.done
+    }
+
+    pub fn text(&self) -> &str {
+        &self.text
+    }
+
+    pub fn finish_reason(&self) -> Option<&str> {
+        self.finish.as_deref()
+    }
+
+    pub fn tool_uses(&self) -> &[ToolUse] {
+        &self.uses
+    }
+
+    /// None when the server sent no usage.
+    pub fn usage(&self) -> Option<&Usage> {
+        self.usage.as_ref()
+    }
+
+    pub fn prompt_tokens(&self) -> u64 {
+        self.prompt
+    }
+
+    fn chunk(&mut self, v: &Value, out: &mut Vec<Event>) {
+        if v["error"].is_object() || v["error"].is_string() {
+            let e = &v["error"];
+            let msg = e["message"].as_str().or_else(|| e.as_str()).unwrap_or("the server reported an error");
+            return out.push(Event::Error(msg.to_string()));
+        }
+        if v["usage"].is_object() {
+            self.merge_usage(&v["usage"]);
+        }
+        let choice = &v["choices"][0];
+        let delta = &choice["delta"];
+        if let Some(s) = delta["content"].as_str().filter(|s| !s.is_empty()) {
+            self.text.push_str(s);
+            out.push(Event::Text(s.to_string()));
+        }
+        // Reasoning text, when the server streams it under either common name.
+        if let Some(s) = ["reasoning_content", "reasoning"].iter().find_map(|k| delta[*k].as_str().filter(|s| !s.is_empty())) {
+            out.push(Event::Thinking(s.to_string()));
+        }
+        for (pos, tc) in delta["tool_calls"].as_array().into_iter().flatten().enumerate() {
+            let idx = tc["index"].as_u64().map_or(pos, |i| i as usize);
+            let c = self.calls.entry(idx).or_default();
+            if c.id.is_empty() {
+                c.id = tc["id"].as_str().unwrap_or_default().to_string();
+            }
+            let f = &tc["function"];
+            if c.name.is_empty() {
+                c.name = f["name"].as_str().unwrap_or_default().to_string();
+            }
+            match &f["arguments"] {
+                Value::String(s) => c.args.push_str(s),
+                Value::Null => {}
+                other => c.args.push_str(&other.to_string()),
+            }
+        }
+        if let Some(r) = choice["finish_reason"].as_str() {
+            self.finish = Some(r.to_string());
+            self.end_round(out);
+        }
+    }
+
+    /// Parses the accumulated tool calls once and announces them.
+    fn end_round(&mut self, out: &mut Vec<Event>) {
+        if self.ended {
+            return;
+        }
+        self.ended = true;
+        self.finish.get_or_insert_with(|| "stop".into());
+        for c in std::mem::take(&mut self.calls).into_values() {
+            let id = if c.id.is_empty() { format!("call_{:08x}", fastrand::u32(..)) } else { c.id };
+            let input = if c.args.trim().is_empty() {
+                Ok(json!({}))
+            } else {
+                serde_json::from_str::<Value>(&c.args).map_err(|e| format!("invalid tool arguments JSON: {e}"))
+            };
+            out.push(Event::ToolStart { id: id.clone(), name: c.name.clone(), args: input.clone().unwrap_or_else(|_| json!({})) });
+            self.uses.push(ToolUse { id, name: c.name, input });
+        }
+    }
+
+    /// Usage can arrive in the last chunk only, or in every chunk; the latest wins.
+    fn merge_usage(&mut self, u: &Value) {
+        let n = |v: &Value| v.as_u64().unwrap_or(0);
+        let prompt = n(&u["prompt_tokens"]);
+        let cached = n(&u["prompt_tokens_details"]["cached_tokens"]);
+        self.prompt = prompt;
+        self.usage = Some(Usage { input: prompt.saturating_sub(cached), output: n(&u["completion_tokens"]), cache_read: cached, cache_write: 0, cost_usd: None });
+    }
+}
+
+#[cfg(not(target_arch = "wasm32"))]
+pub use api::{build_body, build_headers, start, tools_json};
+
+/// The Chat Completions backend: request building and the streaming tool loop.
+#[cfg(not(target_arch = "wasm32"))]
+mod api {
+    use super::*;
+    use crate::chat::events::TurnConfig;
+    use crate::chat::tools::{self, ApiTurn, Ctl, Halt, Sink, CONTINUE_NOTE, CUT_OFF, MAX_TOOL_ROUNDS, STOPPED_BY_USER};
+    use crate::mcp::Out;
+    use base64::{Engine, engine::general_purpose::STANDARD};
+    use std::sync::mpsc::{Receiver, Sender};
+
+    const IMAGE_OMITTED: &str = "[image omitted]";
+    const IMAGE_NOTE: &str = "Image result of the tool call(s) above (a tool message cannot carry an image):";
+
+    // ------------------------------------------------------------------ request
+
+    /// No key header for a keyless local server.
+    pub fn build_headers(key: &str) -> Vec<(&'static str, String)> {
+        let mut h = vec![("content-type", "application/json".to_string())];
+        if !key.is_empty() {
+            h.push(("authorization", format!("Bearer {key}")));
+        }
+        h
+    }
+
+    /// The app's tools as `{"type":"function","function":{name,description,parameters}}`.
+    pub fn tools_json() -> Vec<Value> {
+        tools::tool_specs()
+            .into_iter()
+            .map(|t| json!({"type": "function", "function": {"name": t["name"], "description": t["description"], "parameters": t["inputSchema"]}}))
+            .collect()
+    }
+
+    /// Only the portable fields: no `tool_choice`, no max-token or provider-specific settings.
+    pub fn build_body(cfg: &TurnConfig, tools: &[Value], messages: &[Value]) -> Value {
+        let model = cfg.model.as_deref().unwrap_or(&cfg.endpoint.model);
+        let mut all = vec![];
+        if !cfg.system.is_empty() {
+            all.push(json!({"role": "system", "content": cfg.system}));
+        }
+        all.extend(messages.iter().cloned());
+        json!({
+            "model": model,
+            "stream": true,
+            "stream_options": {"include_usage": true},
+            "tools": tools,
+            "messages": all,
+        })
+    }
+
+    fn data_uri(mime: &str, data: &[u8]) -> String {
+        format!("data:{mime};base64,{}", STANDARD.encode(data))
+    }
+
+    /// A plain string, or the images then the text when images are attached.
+    fn user_content(prompt: &str, images: &[crate::chat::events::ImageAttachment]) -> Value {
+        if images.is_empty() {
+            return json!(prompt);
+        }
+        let mut parts: Vec<Value> = images.iter().map(|i| json!({"type": "image_url", "image_url": {"url": data_uri(&i.mime, &i.data)}})).collect();
+        parts.push(json!({"type": "text", "text": prompt}));
+        Value::Array(parts)
+    }
+
+    /// The `tool` message content: the texts, with `[image omitted]` for each image.
+    fn tool_text(r: &Result<Vec<Out>, String>) -> String {
+        match r {
+            Err(e) => format!("Error: {e}"),
+            Ok(outs) => {
+                let parts: Vec<&str> = outs
+                    .iter()
+                    .map(|o| match o {
+                        Out::Text(t) => t.as_str(),
+                        Out::Image { .. } => IMAGE_OMITTED,
+                    })
+                    .collect();
+                if parts.is_empty() { "OK".into() } else { parts.join("\n") }
+            }
+        }
+    }
+
+    pub fn start(cfg: &TurnConfig, prompt: &str, tx: Sender<Event>) -> Result<ApiTurn, String> {
+        let key = endpoint::get_key(&cfg.endpoint).unwrap_or_default();
+        start_with_key(cfg, prompt, key, tx)
+    }
+
+    pub(super) fn start_with_key(cfg: &TurnConfig, prompt: &str, key: String, tx: Sender<Event>) -> Result<ApiTurn, String> {
+        let mut messages = tools::load_history(cfg.api_history.as_ref())?;
+        messages.push(json!({"role": "user", "content": user_content(prompt, &cfg.images)}));
+        let cfg = cfg.clone();
+        ApiTurn::spawn("chat-openai", move |stop, approvals| {
+            Worker { cfg, key, sink: Sink::new(tx, stop), messages, approvals }.run();
+        })
+    }
+
+    // ------------------------------------------------------------------ worker
+
+    struct Worker {
+        cfg: TurnConfig,
+        key: String,
+        sink: Sink,
+        messages: Vec<Value>,
+        approvals: Receiver<(String, bool)>,
+    }
+
+    struct Round {
+        text: String,
+        uses: Vec<ToolUse>,
+        finish: Option<String>,
+        usage: Option<Usage>,
+        prompt: u64,
+    }
+
+    impl Worker {
+        fn run(mut self) {
+            if let Err(e) = tools::block_on(self.turn()) {
+                self.emit(Event::Error(e));
+            }
+            tools::persist(self.cfg.api_history.as_ref(), &self.messages);
+            // Persist first: the app deletes or reopens the chat as soon as it sees the end.
+            self.sink.flush();
+        }
+
+        fn emit(&self, e: Event) {
+            self.sink.emit(e);
+        }
+
+        fn persist(&self) {
+            tools::persist(self.cfg.api_history.as_ref(), &self.messages);
+        }
+
+        fn model(&self) -> &str {
+            self.cfg.model.as_deref().unwrap_or(&self.cfg.endpoint.model)
+        }
+
+        fn fail(&self, m: String) {
+            self.emit(Event::Error(tools::redact(&m, &self.key)));
+        }
+
+        /// `reported`: some call returned usage; otherwise the turn has no usage row.
+        fn finish(&self, total: &mut Usage, reported: bool, stop_reason: &str) {
+            let usage = reported.then(|| {
+                total.cost_usd = endpoint::cost(self.model(), total);
+                total.clone()
+            });
+            self.emit(Event::TurnEnd { usage, session: None, stop_reason: Some(stop_reason.into()) });
+        }
+
+        /// The assistant message, then one `tool` message per call, then the images (if any) as a
+        /// user message. `results` has one entry per call, in order.
+        fn push_round(&mut self, round: &Round, results: &[Result<Vec<Out>, String>]) {
+            if round.text.is_empty() && round.uses.is_empty() {
+                return;
+            }
+            let mut msg = json!({"role": "assistant", "content": if round.text.is_empty() { Value::Null } else { json!(round.text) }});
+            if !round.uses.is_empty() {
+                msg["tool_calls"] = round
+                    .uses
+                    .iter()
+                    .map(|u| json!({"type": "function", "id": u.id, "function": {"name": u.name, "arguments": u.input.clone().unwrap_or_else(|_| json!({})).to_string()}}))
+                    .collect();
+            }
+            self.messages.push(msg);
+            let mut images: Vec<Value> = vec![];
+            for (u, r) in round.uses.iter().zip(results) {
+                self.messages.push(json!({"role": "tool", "tool_call_id": u.id, "content": tool_text(r)}));
+                for o in r.iter().flatten() {
+                    if let Out::Image { data, mime } = o {
+                        images.push(json!({"type": "image_url", "image_url": {"url": data_uri(mime, data)}}));
+                    }
+                }
+            }
+            if !images.is_empty() {
+                images.insert(0, json!({"type": "text", "text": IMAGE_NOTE}));
+                self.messages.push(json!({"role": "user", "content": images}));
+            }
+        }
+
+        async fn turn(&mut self) {
+            let client = match tools::client() {
+                Ok(c) => c,
+                Err(e) => return self.emit(Event::Error(e)),
+            };
+            let url = match &self.cfg.api_base_url {
+                Some(base) => format!("{}/chat/completions", base.trim_end_matches('/')),
+                None => self.cfg.endpoint.url(),
+            };
+            let tools_body = tools_json();
+            let specs = tools::tool_specs();
+            let mut total = Usage::default();
+            let (mut reported, mut rounds, mut continued) = (false, 0, false);
+            loop {
+                if self.sink.stopped() {
+                    return self.finish(&mut total, reported, "stopped");
+                }
+                let body = build_body(&self.cfg, &tools_body, &self.messages);
+                let round = match self.stream(&client, &url, &body).await {
+                    Ok(r) => r,
+                    Err(Halt::Stopped) => return self.finish(&mut total, reported, "stopped"),
+                    Err(Halt::Reported) => return,
+                    Err(Halt::Fail(m)) => return self.fail(m),
+                };
+                if let Some(u) = &round.usage {
+                    reported = true;
+                    self.emit(Event::Context(round.prompt));
+                    total.input += u.input;
+                    total.output += u.output;
+                    total.cache_read += u.cache_read;
+                }
+                let finish = round.finish.as_deref().unwrap_or("stop");
+                match finish {
+                    "content_filter" => return self.emit(Event::Error("The server's content filter blocked the reply.".into())),
+                    "length" if !continued => {
+                        continued = true;
+                        // Cut-off tool arguments are never run; answer them so the history stays valid.
+                        let results: Vec<_> = round.uses.iter().map(|_| Err(CUT_OFF.to_string())).collect();
+                        self.push_round(&round, &results);
+                        self.messages.push(json!({"role": "user", "content": CONTINUE_NOTE}));
+                        self.persist();
+                    }
+                    "length" => {
+                        let results: Vec<_> = round.uses.iter().map(|_| Err(CUT_OFF.to_string())).collect();
+                        self.push_round(&round, &results);
+                        self.persist();
+                        return self.finish(&mut total, reported, "length");
+                    }
+                    _ if !round.uses.is_empty() => {
+                        if rounds >= MAX_TOOL_ROUNDS {
+                            return self.emit(Event::Error(format!("Stopped after {MAX_TOOL_ROUNDS} tool rounds; send a message to continue.")));
+                        }
+                        // A stop mid-round still records what ran, so the next turn matches the document.
+                        let (results, stopped) = self.run_tools(&specs, &round.uses).await;
+                        self.push_round(&round, &results);
+                        rounds += 1;
+                        self.persist();
+                        if stopped {
+                            return self.finish(&mut total, reported, "stopped");
+                        }
+                    }
+                    other => {
+                        self.push_round(&round, &[]);
+                        self.persist();
+                        return self.finish(&mut total, reported, other);
+                    }
+                }
+            }
+        }
+
+        /// One request; forwards text, reasoning and tool starts as they stream.
+        async fn stream(&self, client: &reqwest::Client, url: &str, body: &Value) -> Result<Round, Halt> {
+            let label = format!("{} API", self.cfg.endpoint.name);
+            let resp = tools::post(&self.sink.stop, client, url, build_headers(&self.key), body, &label).await?;
+            let mut parser = ChatParser::default();
+            let mut errored = false;
+            tools::read_stream(&self.sink.stop, resp, |text| {
+                for ev in parser.push(text) {
+                    if matches!(ev, Event::Error(_)) {
+                        errored = true;
+                    }
+                    self.emit(ev);
+                }
+                parser.done()
+            })
+            .await?;
+            // Some servers close the stream after the last chunk without `[DONE]`.
+            let _ = parser.push("\n");
+            if parser.finish_reason().is_none() {
+                return Err(if errored { Halt::Reported } else { Halt::Fail("The stream ended before the reply was complete.".into()) });
+            }
+            Ok(Round {
+                text: parser.text().to_string(),
+                uses: parser.tool_uses().to_vec(),
+                finish: parser.finish_reason().map(str::to_string),
+                usage: parser.usage().cloned(),
+                prompt: parser.prompt_tokens(),
+            })
+        }
+
+        /// Runs the calls in order, one result each; once stopped, the rest (and the interrupted
+        /// one) get an error result. The flag says whether a stop happened.
+        async fn run_tools(&self, specs: &[Value], uses: &[ToolUse]) -> (Vec<Result<Vec<Out>, String>>, bool) {
+            let emit = |e| self.emit(e);
+            let ctl = Ctl { stop: &self.sink.stop, approvals: &self.approvals, dispatch: self.cfg.tools.as_ref(), emit: &emit };
+            let (mut results, mut stopped) = (vec![], false);
+            for u in uses {
+                let r = match (&u.input, stopped) {
+                    (_, true) => Err(STOPPED_BY_USER.to_string()),
+                    (Err(e), false) => Err(format!("invalid arguments for `{}`: {e}", u.name)),
+                    (Ok(args), false) => ctl.run_one(specs, &u.id, &u.name, args).await.unwrap_or_else(|| {
+                        stopped = true;
+                        Err(STOPPED_BY_USER.to_string())
+                    }),
+                };
+                self.emit(Ctl::end_event(&u.id, &r));
+                results.push(r);
+            }
+            (results, stopped)
+        }
+    }
+
+    #[cfg(test)]
+    mod tests {
+        use super::*;
+        use crate::chat::endpoint::{ApiFormat, Endpoint};
+        use crate::chat::events::ToolDispatch;
+        use crate::chat::tools::test_support::{serve, serve_raw};
+        use std::sync::mpsc::channel;
+        use std::sync::{Arc, Mutex};
+        use std::time::Duration;
+
+        const ROUND1: &str = include_str!("../../tests/fixtures/chat/openai_round1_tools.sse");
+        const ROUND2: &str = include_str!("../../tests/fixtures/chat/openai_round2_end.sse");
+        const TEST_KEY: &str = "sk-test-secret-456";
+
+        fn endpoint() -> Endpoint {
+            Endpoint { id: "local".into(), name: "Local".into(), format: ApiFormat::OpenAi, base_url: "http://127.0.0.1:1/v1".into(), model: "llama-x".into() }
+        }
+
+        fn cfg(name: &str, url: String, tools: Option<ToolDispatch>) -> TurnConfig {
+            let dir = std::env::temp_dir().join(format!("papercraft-openai-{}-{name}", std::process::id()));
+            let _ = std::fs::remove_dir_all(&dir);
+            TurnConfig {
+                system: "sys".into(),
+                api_history: Some(dir.join("chats").join("c.api.json")),
+                api_base_url: Some(url),
+                endpoint: endpoint(),
+                tools,
+                ..Default::default()
+            }
+        }
+
+        fn run(cfg: &TurnConfig, mut on_event: impl FnMut(&ApiTurn, &Event)) -> Vec<Event> {
+            let (tx, rx) = channel();
+            let turn = start_with_key(cfg, "make a board", TEST_KEY.into(), tx).unwrap();
+            let mut out = vec![];
+            while let Ok(e) = rx.recv_timeout(Duration::from_secs(10)) {
+                on_event(&turn, &e);
+                let end = matches!(e, Event::TurnEnd { .. } | Event::Error(_));
+                out.push(e);
+                if end {
+                    break;
+                }
+            }
+            out
+        }
+
+        fn history(cfg: &TurnConfig) -> Vec<Value> {
+            serde_json::from_slice(&std::fs::read(cfg.api_history.as_ref().unwrap()).unwrap()).unwrap()
+        }
+
+        fn fake_tools(calls: Arc<Mutex<Vec<String>>>) -> ToolDispatch {
+            ToolDispatch(Arc::new(move |c| {
+                calls.lock().unwrap().push(c.name.clone());
+                let out = match c.name.as_str() {
+                    "get_basic_info" => vec![Out::Text("info".into()), Out::Image { data: vec![1, 2, 3], mime: "image/png".into() }],
+                    _ => vec![Out::Text("created".into())],
+                };
+                let _ = c.reply.send(Ok(out));
+                true
+            }))
+        }
+
+        #[test]
+        fn request_shape_has_only_portable_fields() {
+            let tools = tools_json();
+            let c = TurnConfig { system: "SYS".into(), model: Some("m".into()), effort: Some("high".into()), endpoint: endpoint(), ..Default::default() };
+            let b = build_body(&c, &tools, &[json!({"role": "user", "content": "hi"})]);
+            let mut keys: Vec<&str> = b.as_object().unwrap().keys().map(String::as_str).collect();
+            keys.sort_unstable();
+            assert_eq!(keys, ["messages", "model", "stream", "stream_options", "tools"]);
+            assert_eq!((b["model"].as_str(), b["stream"].as_bool()), (Some("m"), Some(true)));
+            assert_eq!(b["stream_options"], json!({"include_usage": true}));
+            assert_eq!(b["messages"], json!([{"role": "system", "content": "SYS"}, {"role": "user", "content": "hi"}]));
+            let ts = b["tools"].as_array().unwrap();
+            let names: Vec<String> = crate::mcp::server::tool_list().iter().map(|t| t.name.to_string()).collect();
+            assert_eq!(ts.iter().map(|t| t["function"]["name"].as_str().unwrap().to_string()).collect::<Vec<_>>(), names);
+            assert!(ts.iter().all(|t| t["type"] == "function" && t["function"]["parameters"]["type"] == "object" && t["function"]["description"].is_string()));
+            assert_eq!(tools_json(), tools, "stable across calls");
+            // The model falls back to the endpoint's.
+            assert_eq!(build_body(&TurnConfig { endpoint: endpoint(), ..Default::default() }, &[], &[])["model"], "llama-x");
+            // Even on the Claude host: nothing Claude-only in this format.
+            let on_claude = TurnConfig { endpoint: Endpoint { format: ApiFormat::OpenAi, ..Default::default() }, ..Default::default() };
+            let b = build_body(&on_claude, &tools, &[]);
+            assert!(b.get("output_config").is_none() && b.get("thinking").is_none() && b.get("fallbacks").is_none());
+            assert!(!b.to_string().contains("cache_control") && !b.to_string().contains("eager_input_streaming"));
+        }
+
+        #[test]
+        fn headers_bearer_only_with_a_key() {
+            assert!(build_headers("K").contains(&("authorization", "Bearer K".into())));
+            assert!(build_headers("").iter().all(|(k, _)| *k != "authorization"));
+        }
+
+        #[test]
+        fn attachments_become_image_url_data_uris_before_the_text() {
+            assert_eq!(user_content("hi", &[]), json!("hi"));
+            let img = crate::chat::events::ImageAttachment { mime: "image/png".into(), data: vec![1, 2, 3] };
+            let v = user_content("hi", &[img]);
+            assert_eq!(v[0], json!({"type": "image_url", "image_url": {"url": "data:image/png;base64,AQID"}}));
+            assert_eq!(v[1], json!({"type": "text", "text": "hi"}));
+        }
+
+        #[test]
+        fn tool_loop_two_rounds() {
+            let (url, seen) = serve(vec![ROUND1, ROUND2]);
+            let calls: Arc<Mutex<Vec<String>>> = Arc::default();
+            let c = cfg("loop", url, Some(fake_tools(calls.clone())));
+            let ev = run(&c, |_, _| {});
+            let contexts: Vec<u64> = ev.iter().filter_map(|e| if let Event::Context(n) = e { Some(*n) } else { None }).collect();
+            assert_eq!(contexts, [100, 160], "{ev:?}");
+            let kinds: Vec<&str> = ev
+                .iter()
+                .filter(|e| !matches!(e, Event::Context(_)))
+                .map(|e| match e {
+                    Event::Text(_) => "text",
+                    Event::ToolStart { .. } => "start",
+                    Event::ToolEnd { .. } => "end",
+                    Event::TurnEnd { .. } => "turn",
+                    _ => "other",
+                })
+                .collect();
+            assert_eq!(kinds, ["text", "start", "start", "end", "end", "text", "text", "turn"], "{ev:?}");
+            assert_eq!(*calls.lock().unwrap(), ["create_artboard", "get_basic_info"]);
+            let Event::TurnEnd { usage: Some(u), stop_reason, .. } = ev.last().unwrap() else { panic!() };
+            assert_eq!(stop_reason.as_deref(), Some("stop"));
+            // Round 1: 100 prompt (20 cached), 30 out. Round 2: 160 prompt, 12 out.
+            assert_eq!((u.input, u.output, u.cache_read, u.cache_write), (80 + 160, 42, 20, 0));
+            assert_eq!(u.cost_usd, None, "no price for a non-Claude model");
+
+            let seen = seen.lock().unwrap();
+            let (h1, b1) = &seen[0];
+            assert!(h1.contains(&format!("authorization: bearer {}", TEST_KEY.to_lowercase())));
+            assert!(!h1.iter().any(|h| h.starts_with("x-api-key") || h.starts_with("anthropic")));
+            assert_eq!(b1["messages"].as_array().unwrap().len(), 2, "system + user");
+            let m = seen[1].1["messages"].as_array().unwrap();
+            assert_eq!(m.len(), 6, "system, user, assistant, tool, tool, image user message");
+            assert_eq!(m[2]["role"], "assistant");
+            assert_eq!(m[2]["content"], "Creating it.");
+            assert_eq!(m[2]["tool_calls"][0]["id"], "call_A");
+            assert_eq!(m[2]["tool_calls"][0]["function"]["name"], "create_artboard");
+            let args: Value = serde_json::from_str(m[2]["tool_calls"][0]["function"]["arguments"].as_str().unwrap()).unwrap();
+            assert_eq!(args, json!({"name": "Home", "styles": {"width": "1440px", "height": "900px"}}));
+            assert_eq!(m[3], json!({"role": "tool", "tool_call_id": "call_A", "content": "created"}));
+            assert_eq!(m[4], json!({"role": "tool", "tool_call_id": "call_B", "content": "info\n[image omitted]"}));
+            assert_eq!(m[5]["role"], "user");
+            assert_eq!(m[5]["content"][1], json!({"type": "image_url", "image_url": {"url": "data:image/png;base64,AQID"}}));
+
+            let h = history(&c);
+            assert_eq!(h.len(), 6, "user, assistant, tool, tool, image, final assistant");
+            assert_eq!(h[..5], m[1..]);
+            assert_eq!(h[5], json!({"role": "assistant", "content": "Done: board ready."}));
+            assert!(!serde_json::to_string(&h).unwrap().contains(TEST_KEY), "key must never reach the history file");
+        }
+
+        fn delete_round() -> &'static str {
+            let call = r#"{"id":"c","choices":[{"index":0,"delta":{"tool_calls":[{"index":0,"id":"call_D","type":"function","function":{"name":"delete_pages","arguments":"{\"pageIds\":[\"p1\"]}"}}]}}]}"#;
+            let fin = r#"{"id":"c","choices":[{"index":0,"delta":{},"finish_reason":"tool_calls"}]}"#;
+            Box::leak(format!("data: {call}\n\ndata: {fin}\n\ndata: [DONE]\n\n").into_boxed_str())
+        }
+
+        #[test]
+        fn destructive_tool_waits_for_approval() {
+            for (ok, name) in [(false, "deny"), (true, "allow")] {
+                let (url, seen) = serve(vec![delete_round(), ROUND2]);
+                let calls: Arc<Mutex<Vec<String>>> = Arc::default();
+                let c = cfg(name, url, Some(fake_tools(calls.clone())));
+                let ev = run(&c, |t, e| {
+                    if let Event::NeedsApproval { id, .. } = e {
+                        t.approve(id, ok);
+                    }
+                });
+                assert!(ev.iter().any(|e| matches!(e, Event::NeedsApproval { name, .. } if name == "delete_pages")), "{ev:?}");
+                assert!(matches!(ev.last(), Some(Event::TurnEnd { .. })), "{ev:?}");
+                assert_eq!(calls.lock().unwrap().len(), usize::from(ok));
+                if !ok {
+                    let tool_msg = &seen.lock().unwrap()[1].1["messages"][3];
+                    assert!(tool_msg["content"].as_str().unwrap().contains("denied"), "{tool_msg}");
+                }
+            }
+        }
+
+        #[test]
+        fn invalid_input_and_bad_json_go_back_as_errors() {
+            let bad = r#"{"id":"c","choices":[{"index":0,"delta":{"tool_calls":[{"index":0,"id":"c1","function":{"name":"create_artboard","arguments":"{\"name\": 5}"}},{"index":1,"id":"c2","function":{"name":"get_basic_info","arguments":"{oops"}}]}}]}"#;
+            let fin = r#"{"id":"c","choices":[{"index":0,"delta":{},"finish_reason":"tool_calls"}]}"#;
+            let round: &'static str = Box::leak(format!("data: {bad}\n\ndata: {fin}\n\ndata: [DONE]\n\n").into_boxed_str());
+            let (url, seen) = serve(vec![round, ROUND2]);
+            let calls: Arc<Mutex<Vec<String>>> = Arc::default();
+            let ev = run(&cfg("invalid", url, Some(fake_tools(calls.clone()))), |_, _| {});
+            assert!(matches!(ev.last(), Some(Event::TurnEnd { .. })), "{ev:?}");
+            assert!(calls.lock().unwrap().is_empty());
+            let m = seen.lock().unwrap()[1].1["messages"].clone();
+            assert!(m[3]["content"].as_str().unwrap().starts_with("Error: invalid input for `create_artboard`"), "{}", m[3]);
+            assert!(m[4]["content"].as_str().unwrap().contains("invalid arguments"), "{}", m[4]);
+        }
+
+        #[test]
+        fn http_error_shows_message_and_redacts_the_key() {
+            let b = format!(r#"{{"error":{{"message":"bad key {TEST_KEY}"}}}}"#);
+            let (url, _) = serve_raw(vec![format!("HTTP/1.1 401 Unauthorized\r\ncontent-length: {}\r\nconnection: close\r\n\r\n{b}", b.len())]);
+            let ev = run(&cfg("401", url, None), |_, _| {});
+            let Some(Event::Error(m)) = ev.last() else { panic!("{ev:?}") };
+            assert!(m.contains("401") && m.contains("bad key") && !m.contains(TEST_KEY), "{m}");
+        }
+
+        #[test]
+        fn round_cap_is_forty() {
+            let (url, seen) = serve(vec![delete_round_plain(); MAX_TOOL_ROUNDS + 1]);
+            let calls: Arc<Mutex<Vec<String>>> = Arc::default();
+            let ev = run(&cfg("cap", url, Some(fake_tools(calls))), |_, _| {});
+            let Some(Event::Error(m)) = ev.last() else { panic!("{ev:?}") };
+            assert!(m.contains("Stopped after"), "{m}");
+            assert_eq!(seen.lock().unwrap().len(), MAX_TOOL_ROUNDS + 1);
+        }
+
+        fn delete_round_plain() -> &'static str {
+            let call = r#"{"id":"c","choices":[{"index":0,"delta":{"tool_calls":[{"index":0,"id":"c1","function":{"name":"get_basic_info","arguments":"{}"}}]}}]}"#;
+            let fin = r#"{"id":"c","choices":[{"index":0,"delta":{},"finish_reason":"tool_calls"}]}"#;
+            Box::leak(format!("data: {call}\n\ndata: {fin}\n\ndata: [DONE]\n\n").into_boxed_str())
+        }
+
+        #[test]
+        fn history_is_on_disk_before_the_end_event() {
+            let (url, _) = serve(vec![ROUND2]);
+            let c = cfg("persist_first", url, None);
+            let path = c.api_history.clone().unwrap();
+            let mut on_disk = None;
+            run(&c, |_, e| {
+                if matches!(e, Event::TurnEnd { .. }) {
+                    on_disk = Some(path.exists());
+                }
+            });
+            assert_eq!(on_disk, Some(true));
+        }
+
+        #[test]
+        fn stop_ends_a_hanging_stream_fast() {
+            use std::io::{Read, Write};
+            let l = std::net::TcpListener::bind("127.0.0.1:0").unwrap();
+            let url = format!("http://{}", l.local_addr().unwrap());
+            std::thread::spawn(move || {
+                let (mut s, _) = l.accept().unwrap();
+                let mut buf = [0; 8192];
+                let _ = s.read(&mut buf);
+                let _ = write!(s, "HTTP/1.1 200 OK\r\ncontent-type: text/event-stream\r\n\r\n: hold\n\n");
+                std::thread::sleep(Duration::from_secs(20));
+            });
+            let (tx, rx) = channel();
+            use crate::chat::events::Turn;
+            let mut turn = start_with_key(&cfg("stop", url, None), "x", TEST_KEY.into(), tx).unwrap();
+            std::thread::sleep(Duration::from_millis(400));
+            turn.stop();
+            let e = rx.recv_timeout(Duration::from_secs(3)).unwrap();
+            assert!(matches!(e, Event::TurnEnd { stop_reason: Some(ref r), .. } if r == "stopped"), "{e:?}");
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    // SYNTHETIC fixture, hand-written from the documented Chat Completions streaming shape.
+    const TOOLS: &str = include_str!("../../tests/fixtures/chat/openai_tools.sse");
+
+    /// Feed in awkward 7-byte chunks (fixtures are ASCII) to prove line buffering.
+    fn run(src: &str) -> (ChatParser, Vec<Event>) {
+        let mut p = ChatParser::default();
+        let ev = src.as_bytes().chunks(7).flat_map(|c| p.push(std::str::from_utf8(c).unwrap())).collect();
+        (p, ev)
+    }
+
+    #[test]
+    fn two_parallel_tool_calls_split_across_chunks() {
+        let (p, ev) = run(TOOLS);
+        assert_eq!(
+            ev,
+            vec![
+                Event::Thinking("Need an artboard.".into()),
+                Event::Text("Creating ".into()),
+                Event::Text("the home screen.".into()),
+                Event::ToolStart { id: "call_A".into(), name: "create_artboard".into(), args: json!({"name": "Home", "width": 1440}) },
+                Event::ToolStart { id: "call_B".into(), name: "get_basic_info".into(), args: json!({}) },
+            ]
+        );
+        assert_eq!(p.text(), "Creating the home screen.");
+        assert_eq!(p.finish_reason(), Some("tool_calls"));
+        assert_eq!(p.tool_uses().len(), 2);
+        let u = p.usage().unwrap();
+        assert_eq!((u.input, u.output, u.cache_read), (120, 87, 900));
+        assert_eq!(p.prompt_tokens(), 1020);
+        assert!(p.done());
+    }
+
+    #[test]
+    fn no_usage_missing_ids_and_object_arguments_are_tolerated() {
+        let mut p = ChatParser::default();
+        let ev = p.push(
+            "data: {\"choices\":[{\"delta\":{\"tool_calls\":[{\"function\":{\"name\":\"get_basic_info\",\"arguments\":{\"a\":1}}}]},\"finish_reason\":\"stop\"}]}\n\n",
+        );
+        let Event::ToolStart { id, name, args } = &ev[0] else { panic!("{ev:?}") };
+        assert!(id.starts_with("call_") && id.len() > 5);
+        assert_eq!((name.as_str(), args), ("get_basic_info", &json!({"a": 1})));
+        assert!(p.usage().is_none());
+        assert!(!p.done(), "no [DONE] yet");
+    }
+
+    #[test]
+    fn bad_arguments_json_is_kept_as_an_error_not_a_panic() {
+        let mut p = ChatParser::default();
+        p.push("data: {\"choices\":[{\"delta\":{\"tool_calls\":[{\"index\":0,\"id\":\"t\",\"function\":{\"name\":\"x\",\"arguments\":\"{\\\"a\\\"\"}}]},\"finish_reason\":\"tool_calls\"}]}\n");
+        assert!(p.tool_uses()[0].input.as_ref().unwrap_err().contains("invalid tool arguments"));
+    }
+
+    #[test]
+    fn in_stream_error_object() {
+        let mut p = ChatParser::default();
+        let ev = p.push("data: {\"error\":{\"message\":\"rate limited\"}}\n");
+        assert_eq!(ev, vec![Event::Error("rate limited".into())]);
+    }
+}
@@ -0,0 +1,150 @@
+//! The PATH agents are found and run with. An app opened from the Dock gets the bare system PATH
+//! (`/usr/bin:/bin:/usr/sbin:/sbin`), so `~/.local/bin` and Homebrew are invisible. The login
+//! shell's PATH is read once, off the UI thread, and merged with the process PATH and the usual
+//! install folders.
+
+use std::ffi::{OsStr, OsString};
+use std::io::Read;
+use std::path::{Path, PathBuf};
+use std::process::{Command, Stdio};
+use std::sync::OnceLock;
+use std::time::{Duration, Instant};
+
+const SHELL_TIMEOUT: Duration = Duration::from_secs(3);
+const POLL: Duration = Duration::from_millis(20);
+/// The PATH is framed by markers: rc/exit-hook noise on stdout before or after cannot replace it.
+const SHELL_SCRIPT: &str = r#"printf '\n__PC_PATH_BEGIN__%s__PC_PATH_END__\n' "$PATH""#;
+const PATH_BEGIN: &str = "__PC_PATH_BEGIN__";
+const PATH_END: &str = "__PC_PATH_END__";
+/// Same keys the agent spawns drop: a login shell must not hand them to anything.
+pub(super) const CREDENTIAL_ENV: [&str; 4] = ["ANTHROPIC_API_KEY", "ANTHROPIC_AUTH_TOKEN", "OPENAI_API_KEY", "CODEX_API_KEY"];
+/// Under `$HOME`.
+const HOME_DIRS: [&str; 6] = [".local/bin", ".cargo/bin", ".bun/bin", ".npm-global/bin", ".volta/bin", ".nvm/current/bin"];
+const SYSTEM_DIRS: [&str; 2] = ["/opt/homebrew/bin", "/usr/local/bin"];
+
+static RESOLVED: OnceLock<String> = OnceLock::new();
+
+/// Starts resolving in the background; call once at app start.
+pub fn init() {
+    std::thread::spawn(|| {
+        resolved_path();
+    });
+}
+
+/// The merged PATH. Blocks only while the first resolution is still running.
+pub fn resolved_path() -> &'static str {
+    RESOLVED.get_or_init(|| {
+        let shell = std::env::var("SHELL").ok().filter(|_| cfg!(unix)).and_then(|s| shell_path(&s, SHELL_SCRIPT, SHELL_TIMEOUT));
+        let home = std::env::var_os("HOME").map(PathBuf::from);
+        let extras = HOME_DIRS.iter().filter_map(|d| home.as_ref().map(|h| h.join(d))).chain(SYSTEM_DIRS.iter().map(PathBuf::from)).filter(|d| d.is_dir()).collect();
+        merge(shell.as_deref().unwrap_or_default(), &std::env::var_os("PATH").unwrap_or_default(), extras)
+    })
+}
+
+/// Shell PATH first (the user's own order), then the process PATH, then the extra folders; each
+/// folder once.
+fn merge(shell: &str, process: &OsStr, extras: Vec<PathBuf>) -> String {
+    let mut out: Vec<PathBuf> = vec![];
+    for d in std::env::split_paths(shell).chain(std::env::split_paths(process)).chain(extras) {
+        if !d.as_os_str().is_empty() && !out.contains(&d) {
+            out.push(d);
+        }
+    }
+    std::env::join_paths(out).map(|p| p.to_string_lossy().into_owned()).unwrap_or_default()
+}
+
+/// Runs `shell -l -c script` and returns the text between the PATH markers; None on failure or timeout.
+fn shell_path(shell: &str, script: &str, timeout: Duration) -> Option<String> {
+    let mut cmd = Command::new(shell);
+    cmd.args(["-l", "-c", script]).stdin(Stdio::null()).stdout(Stdio::piped()).stderr(Stdio::null());
+    for k in CREDENTIAL_ENV {
+        cmd.env_remove(k);
+    }
+    let mut child = cmd.spawn().ok()?;
+    let mut stdout = child.stdout.take()?;
+    // Read on a thread: a shell stuck in an rc file never closes the pipe.
+    let (tx, rx) = std::sync::mpsc::channel();
+    std::thread::spawn(move || {
+        let mut s = String::new();
+        let _ = stdout.read_to_string(&mut s);
+        let _ = tx.send(s);
+    });
+    let start = Instant::now();
+    let out = loop {
+        match rx.recv_timeout(POLL) {
+            Ok(s) => break Some(s),
+            Err(_) if start.elapsed() >= timeout => break None,
+            Err(_) => {}
+        }
+    };
+    let _ = child.kill();
+    let _ = child.wait();
+    let out = out?;
+    let from = out.rfind(PATH_BEGIN)? + PATH_BEGIN.len();
+    let len = out[from..].find(PATH_END)?;
+    Some(out[from..from + len].trim().to_string()).filter(|p| !p.is_empty())
+}
+
+/// First executable named `name` on the resolved PATH.
+pub fn which(name: &str) -> Option<PathBuf> {
+    which_in(name, OsStr::new(resolved_path()))
+}
+
+pub(super) fn which_in(name: &str, path: &OsStr) -> Option<PathBuf> {
+    let names: Vec<String> = if cfg!(windows) { ["exe", "cmd", "bat"].iter().map(|e| format!("{name}.{e}")).collect() } else { vec![name.into()] };
+    std::env::split_paths(path).flat_map(|d| names.iter().map(move |n| d.join(n))).find(|p| is_executable(p))
+}
+
+fn is_executable(p: &Path) -> bool {
+    #[cfg(unix)]
+    {
+        use std::os::unix::fs::PermissionsExt;
+        p.metadata().is_ok_and(|m| m.is_file() && m.permissions().mode() & 0o111 != 0)
+    }
+    #[cfg(not(unix))]
+    p.is_file()
+}
+
+/// Sets the merged PATH on a child, so node-based CLIs find `node`.
+pub fn apply(cmd: &mut Command) -> &mut Command {
+    cmd.env("PATH", OsString::from(resolved_path()))
+}
+
+#[cfg(all(test, unix))]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn merge_dedupes_and_keeps_order() {
+        let m = merge("/a:/b:/a", OsStr::new("/b:/c::/d"), vec!["/d".into(), "/e".into()]);
+        assert_eq!(m, "/a:/b:/c:/d:/e");
+    }
+
+    #[test]
+    fn which_finds_only_executables_on_the_given_path() {
+        use std::os::unix::fs::PermissionsExt;
+        let dir = std::env::temp_dir().join(format!("pc-path-{}", fastrand::u64(..)));
+        std::fs::create_dir_all(&dir).unwrap();
+        let (bin, plain) = (dir.join("fake-agent"), dir.join("not-exec"));
+        std::fs::write(&bin, "#!/bin/sh\n").unwrap();
+        std::fs::write(&plain, "x").unwrap();
+        std::fs::set_permissions(&bin, std::fs::Permissions::from_mode(0o755)).unwrap();
+        let path = std::env::join_paths(["/nonexistent", dir.to_str().unwrap()]).unwrap();
+        assert_eq!(which_in("fake-agent", &path), Some(bin));
+        assert_eq!(which_in("not-exec", &path), None);
+        assert_eq!(which_in("missing", &path), None);
+        std::fs::remove_dir_all(&dir).unwrap();
+    }
+
+    #[test]
+    fn shell_path_reads_between_markers_and_times_out() {
+        let script = r#"echo noise; printf '\n__PC_PATH_BEGIN__%s__PC_PATH_END__\n' /x:/y; echo exit-hook-noise"#;
+        assert_eq!(shell_path("/bin/sh", script, Duration::from_secs(3)).as_deref(), Some("/x:/y"));
+        assert_eq!(shell_path("/bin/sh", SHELL_SCRIPT, Duration::from_secs(3)).is_some(), true);
+        assert_eq!(shell_path("/bin/sh", "echo /only/noise", Duration::from_secs(3)), None);
+        let t = Instant::now();
+        assert_eq!(shell_path("/bin/sh", "sleep 10", Duration::from_millis(200)), None);
+        assert!(t.elapsed() < Duration::from_secs(3));
+        assert_eq!(shell_path("/nonexistent-shell", SHELL_SCRIPT, Duration::from_secs(1)), None);
+    }
+}
@@ -0,0 +1,202 @@
+//! Chat files in the project folder: `chats/<id>.json`, plus `chats/<id>.api.json` for the raw
+//! Anthropic API messages (exact replay, thinking blocks included).
+
+use super::{valid_id, Chat, TMP_DIR};
+use crate::vfs;
+use std::path::{Path, PathBuf};
+
+const DIR: &str = "chats";
+const API_SUFFIX: &str = ".api.json";
+
+pub use crate::project::format::new_id;
+
+fn dir(project: &Path) -> PathBuf {
+    project.join(DIR)
+}
+
+fn file_of(project: &Path, id: &str) -> PathBuf {
+    dir(project).join(format!("{id}.json"))
+}
+
+pub fn save(project: &Path, chat: &Chat) -> std::io::Result<()> {
+    if !valid_id(&chat.id) {
+        return Err(std::io::Error::new(std::io::ErrorKind::InvalidInput, "invalid chat id"));
+    }
+    vfs::create_dir_all(dir(project))?;
+    let bytes = serde_json::to_vec(chat).map_err(std::io::Error::other)?;
+    vfs::write(file_of(project, &chat.id), bytes)
+}
+
+pub fn load(project: &Path, id: &str) -> Option<Chat> {
+    if !valid_id(id) {
+        return None;
+    }
+    serde_json::from_slice(&vfs::read(file_of(project, id)).ok()?).ok()
+}
+
+/// Every readable chat, newest updated first. Unreadable files are skipped.
+pub fn list(project: &Path) -> Vec<Chat> {
+    let Ok(entries) = vfs::read_dir(dir(project)) else {
+        return Vec::new();
+    };
+    let mut out: Vec<Chat> = entries
+        .flatten()
+        .filter(|e| e.path().extension().is_some_and(|x| x == "json"))
+        .filter(|e| !e.path().to_string_lossy().ends_with(API_SUFFIX))
+        .filter_map(|e| serde_json::from_slice::<Chat>(&vfs::read(e.path()).ok()?).ok())
+        .filter(|c| valid_id(&c.id))
+        .collect();
+    out.sort_by_key(|c| std::cmp::Reverse(c.updated));
+    out
+}
+
+/// Removes the chat and its API replay file, if there is one.
+pub fn delete(project: &Path, id: &str) {
+    if !valid_id(id) {
+        return;
+    }
+    let _ = vfs::remove_file(file_of(project, id));
+    let _ = vfs::remove_file(dir(project).join(format!("{id}{API_SUFFIX}")));
+}
+
+/// Folder of the images saved for chat `id`; None when `id` is not a plain name.
+pub fn tmp_of(project: &Path, id: &str) -> Option<PathBuf> {
+    valid_id(id).then(|| project.join(TMP_DIR).join(id))
+}
+
+/// Removes the chat's saved images, only when the folder really lies inside
+/// `<project>/.papercraft-chat-tmp` (a symlink pointing elsewhere is left alone).
+pub fn remove_tmp(project: &Path, id: &str) {
+    let Some(folder) = tmp_of(project, id) else { return };
+    let (Ok(root), Ok(real)) = (std::fs::canonicalize(project.join(TMP_DIR)), std::fs::canonicalize(&folder)) else { return };
+    if real != root && real.starts_with(&root) {
+        let _ = vfs::remove_dir_all(real);
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::chat::{Backend, BackendKind, Message, Role, ToolCall, Usage};
+
+    fn temp_project() -> PathBuf {
+        std::env::temp_dir().join(format!("papercraft-chat-{:016x}", fastrand::u64(..)))
+    }
+
+    fn chat(id: &str, updated: u64) -> Chat {
+        Chat {
+            id: id.into(),
+            title: format!("Chat {id}"),
+            created: 1,
+            updated,
+            backend: Backend {
+                kind: BackendKind::Codex,
+                model: Some("gpt-6.1-sol".into()),
+                effort: None,
+                endpoint: None,
+                cli_session: Some("s1".into()),
+                agent: None,
+            },
+            messages: vec![Message {
+                role: Role::Assistant,
+                text: "Done".into(),
+                tools: vec![ToolCall {
+                    id: "t1".into(),
+                    name: "create_artboard".into(),
+                    args: serde_json::json!({ "w": 390 }),
+                    result: Some(serde_json::json!({ "ok": true })),
+                    error: None,
+                    ms: Some(12),
+                }],
+                run_id: Some("r1".into()),
+                context: Some(7),
+                usage: Some(Usage {
+                    input: 10,
+                    output: 4,
+                    cache_read: 2,
+                    cache_write: 0,
+                    cost_usd: Some(0.5),
+                }),
+                at: 5,
+            }],
+        }
+    }
+
+    #[test]
+    fn chat_round_trips() {
+        let dir = temp_project();
+        let c = chat("aaaa", 3);
+        save(&dir, &c).unwrap();
+        assert_eq!(load(&dir, "aaaa"), Some(c));
+        std::fs::remove_dir_all(dir).ok();
+    }
+
+    #[test]
+    fn list_orders_newest_first_and_skips_unreadable() {
+        let dir = temp_project();
+        save(&dir, &chat("old", 1)).unwrap();
+        save(&dir, &chat("new", 9)).unwrap();
+        vfs::write(dir.join(DIR).join("broken.json"), b"{not json").unwrap();
+        let ids: Vec<String> = list(&dir).into_iter().map(|c| c.id).collect();
+        assert_eq!(ids, vec!["new", "old"]);
+        std::fs::remove_dir_all(dir).ok();
+    }
+
+    #[test]
+    fn delete_removes_chat_and_api_file() {
+        let dir = temp_project();
+        save(&dir, &chat("a", 1)).unwrap();
+        vfs::write(dir.join(DIR).join("a.api.json"), b"[]").unwrap();
+        delete(&dir, "a");
+        assert!(!dir.join(DIR).join("a.json").exists());
+        assert!(!dir.join(DIR).join("a.api.json").exists());
+        assert!(list(&dir).is_empty());
+        std::fs::remove_dir_all(dir).ok();
+    }
+
+    #[test]
+    fn hostile_ids_never_reach_the_file_system() {
+        let dir = temp_project();
+        let outside = dir.join("victim");
+        std::fs::create_dir_all(&outside).unwrap();
+        std::fs::create_dir_all(dir.join(TMP_DIR)).unwrap();
+        for id in ["..", "../victim", "a/b", ".", "", "a.b", "..\\victim"] {
+            assert!(!valid_id(id), "{id}");
+            assert!(tmp_of(&dir, id).is_none());
+            remove_tmp(&dir, id);
+            delete(&dir, id);
+            assert!(load(&dir, id).is_none());
+            assert!(save(&dir, &chat(id, 1)).is_err());
+        }
+        assert!(outside.exists());
+        assert!(dir.join(TMP_DIR).exists(), "the tmp root itself survives");
+        // A file on disk whose content claims a hostile id is not listed.
+        std::fs::create_dir_all(dir.join(DIR)).unwrap();
+        vfs::write(dir.join(DIR).join("x.json"), br#"{"id":"../victim"}"#).unwrap();
+        assert!(list(&dir).is_empty());
+        std::fs::remove_dir_all(dir).ok();
+    }
+
+    #[cfg(unix)]
+    #[test]
+    fn remove_tmp_ignores_a_symlink_out_of_the_tmp_dir() {
+        let dir = temp_project();
+        let outside = dir.join("victim");
+        std::fs::create_dir_all(&outside).unwrap();
+        std::fs::write(outside.join("keep"), b"x").unwrap();
+        std::fs::create_dir_all(dir.join(TMP_DIR)).unwrap();
+        std::os::unix::fs::symlink(&outside, dir.join(TMP_DIR).join("abc")).unwrap();
+        remove_tmp(&dir, "abc");
+        assert!(outside.join("keep").exists());
+        std::fs::remove_dir_all(dir).ok();
+    }
+
+    #[test]
+    fn project_without_chats_dir_lists_empty() {
+        let dir = temp_project();
+        std::fs::create_dir_all(&dir).unwrap();
+        assert!(list(&dir).is_empty());
+        assert!(load(&dir, "x").is_none());
+        std::fs::remove_dir_all(dir).ok();
+    }
+}
@@ -0,0 +1,444 @@
+//! Pieces shared by the two API loops (`anthropic`, `openai`): the tool list, the input validator,
+//! approvals, running a tool on the UI thread, the turn handle, the event sink and the HTTP
+//! request with its stop polling.
+
+use super::events::{Event, ToolDispatch, Turn};
+use crate::mcp::Out;
+use base64::{engine::general_purpose::STANDARD, Engine};
+use serde_json::{json, Value};
+use std::sync::atomic::{AtomicBool, Ordering};
+use std::sync::mpsc::{channel, Receiver, RecvTimeoutError, Sender};
+use std::sync::Arc;
+use std::time::Duration;
+
+pub const MAX_TOOL_ROUNDS: usize = 40;
+/// How often blocking waits look at the stop flag (stop must end the turn within 3 s).
+pub const POLL: Duration = Duration::from_millis(100);
+const CONNECT_TIMEOUT: Duration = Duration::from_secs(15);
+const READ_TIMEOUT: Duration = Duration::from_secs(120);
+/// An HTTP error body is a short JSON message; never buffer more than this.
+const ERROR_BODY_MAX: usize = 64 * 1024;
+pub const STOPPED_BY_USER: &str = "stopped by user; this call was not completed or its outcome is unknown";
+pub const DENIED: &str = "The user denied this action.";
+/// Tool results above this many layers in one `delete_nodes` need the user's approval.
+const DELETE_NODES_CONFIRM_ABOVE: usize = 20;
+pub const CONTINUE_NOTE: &str = "Your previous reply was cut off by the output limit. Continue where you stopped.";
+pub const CUT_OFF: &str = "output limit reached before the call finished; not run";
+
+/// The app's tools as `{name, description, inputSchema}`, in `tool_list()` order.
+pub fn tool_specs() -> Vec<Value> {
+    crate::mcp::server::tool_list()
+        .iter()
+        .filter_map(|t| serde_json::to_value(t).ok())
+        .map(|t| json!({"name": t["name"], "description": t["description"], "inputSchema": t["inputSchema"]}))
+        .collect()
+}
+
+// ---------------------------------------------------------------------- validation
+
+/// Minimal JSON-schema check: object shape, required fields, and the JSON type of each
+/// declared property (recursing into properties and array items).
+pub fn validate_input(schema: &Value, input: &Value) -> Result<(), String> {
+    check(schema, input, "input")
+}
+
+fn type_ok(t: &str, v: &Value) -> bool {
+    match t {
+        "string" => v.is_string(),
+        "boolean" => v.is_boolean(),
+        "number" => v.is_number(),
+        "integer" => v.is_i64() || v.is_u64() || v.as_f64().is_some_and(|f| f.fract() == 0.0),
+        "array" => v.is_array(),
+        "object" => v.is_object(),
+        "null" => v.is_null(),
+        _ => true,
+    }
+}
+
+fn check(schema: &Value, v: &Value, path: &str) -> Result<(), String> {
+    let ok = match schema.get("type") {
+        Some(Value::String(t)) => type_ok(t, v),
+        Some(Value::Array(ts)) => ts.iter().filter_map(Value::as_str).any(|t| type_ok(t, v)),
+        _ => true,
+    };
+    if !ok {
+        return Err(format!("{path}: expected {}, got {v}", schema["type"]));
+    }
+    if let Some(e) = schema["enum"].as_array() {
+        if !e.contains(v) {
+            return Err(format!("{path}: {v} is not one of {}", schema["enum"]));
+        }
+    }
+    if let Some(n) = v.as_f64() {
+        if schema["minimum"].as_f64().is_some_and(|m| n < m) {
+            return Err(format!("{path}: {n} is below the minimum {}", schema["minimum"]));
+        }
+        if schema["maximum"].as_f64().is_some_and(|m| n > m) {
+            return Err(format!("{path}: {n} is above the maximum {}", schema["maximum"]));
+        }
+    }
+    if let Some(s) = v.as_str() {
+        if schema["minLength"].as_u64().is_some_and(|m| (s.chars().count() as u64) < m) {
+            return Err(format!("{path}: shorter than {} characters", schema["minLength"]));
+        }
+    }
+    // anyOf / oneOf: at least one branch must accept (oneOf's "exactly one" is not enforced).
+    for key in ["anyOf", "oneOf"] {
+        if let Some(branches) = schema[key].as_array() {
+            if !branches.iter().any(|b| check(b, v, path).is_ok()) {
+                return Err(format!("{path}: {v} matches none of the allowed {key} shapes"));
+            }
+        }
+    }
+    if let Some(o) = v.as_object() {
+        for r in schema["required"].as_array().into_iter().flatten().filter_map(Value::as_str) {
+            if !o.contains_key(r) {
+                return Err(format!("{path}: missing required field `{r}`"));
+            }
+        }
+        let props = schema["properties"].as_object();
+        for (k, val) in o {
+            let child = format!("{path}.{k}");
+            match (props.and_then(|p| p.get(k)), &schema["additionalProperties"]) {
+                (Some(s), _) => check(s, val, &child)?,
+                (None, Value::Bool(false)) => return Err(format!("{path}: unexpected field `{k}`")),
+                (None, extra @ Value::Object(_)) => check(extra, val, &child)?,
+                _ => {}
+            }
+        }
+    }
+    if let Some(a) = v.as_array() {
+        if schema["minItems"].as_u64().is_some_and(|m| (a.len() as u64) < m) {
+            return Err(format!("{path}: needs at least {} items", schema["minItems"]));
+        }
+        if let Some(items) = schema.get("items") {
+            for (i, x) in a.iter().enumerate() {
+                check(items, x, &format!("{path}[{i}]"))?;
+            }
+        }
+    }
+    Ok(())
+}
+
+/// Destructive tools wait for the user (spec, Confirmation).
+pub fn needs_approval(name: &str, args: &Value) -> bool {
+    match name {
+        "delete_pages" | "disable_library" | "import_design_system" => true,
+        "delete_nodes" => args["nodeIds"].as_array().is_some_and(|a| a.len() > DELETE_NODES_CONFIRM_ABOVE),
+        _ => false,
+    }
+}
+
+// ---------------------------------------------------------------------- running a tool
+
+/// Tool output as content blocks (text and base64 images) for the `ToolEnd` event and the
+/// Messages API; never empty.
+pub fn out_blocks(outs: &[Out]) -> Vec<Value> {
+    let mut v: Vec<Value> = outs
+        .iter()
+        .map(|o| match o {
+            Out::Text(t) => json!({"type": "text", "text": t}),
+            Out::Image { data, mime } => json!({"type": "image", "source": {"type": "base64", "media_type": mime, "data": STANDARD.encode(data)}}),
+        })
+        .collect();
+    if v.is_empty() {
+        v.push(json!({"type": "text", "text": "OK"}));
+    }
+    v
+}
+
+/// What a tool run needs from its worker.
+pub struct Ctl<'a> {
+    pub stop: &'a AtomicBool,
+    pub approvals: &'a Receiver<(String, bool)>,
+    pub dispatch: Option<&'a ToolDispatch>,
+    pub emit: &'a dyn Fn(Event),
+}
+
+impl Ctl<'_> {
+    fn stopped(&self) -> bool {
+        self.stop.load(Ordering::SeqCst)
+    }
+
+    /// Validates, waits for approval when needed, runs on the UI thread. `None` = stopped.
+    pub async fn run_one(&self, specs: &[Value], id: &str, name: &str, args: &Value) -> Option<Result<Vec<Out>, String>> {
+        let Some(tool) = specs.iter().find(|t| t["name"] == name) else {
+            return Some(Err(format!("unknown tool `{name}`")));
+        };
+        if let Err(e) = validate_input(&tool["inputSchema"], args) {
+            return Some(Err(format!("invalid input for `{name}`: {e}")));
+        }
+        if needs_approval(name, args) {
+            (self.emit)(Event::NeedsApproval { id: id.into(), name: name.into(), args: args.clone() });
+            loop {
+                if self.stopped() {
+                    return None;
+                }
+                match self.approvals.recv_timeout(POLL) {
+                    Ok((i, ok)) if i == id => {
+                        if ok {
+                            break;
+                        }
+                        return Some(Err(DENIED.into()));
+                    }
+                    Ok(_) | Err(RecvTimeoutError::Timeout) => {}
+                    Err(RecvTimeoutError::Disconnected) => return Some(Err(DENIED.into())),
+                }
+            }
+        }
+        let Some(d) = self.dispatch else { return Some(Err("tools are not available".into())) };
+        let (reply, mut rx) = tokio::sync::oneshot::channel();
+        if !(d.0)(crate::mcp::Call { name: name.into(), args: args.clone(), reply }) {
+            return Some(Err("the app is not accepting tool calls".into()));
+        }
+        loop {
+            match tokio::time::timeout(POLL, &mut rx).await {
+                Ok(Ok(r)) => return Some(r),
+                Ok(Err(_)) => return Some(Err("the app dropped the tool call".into())),
+                Err(_) if self.stopped() => return None,
+                Err(_) => {}
+            }
+        }
+    }
+
+    /// The `ToolEnd` event for a finished call.
+    pub fn end_event(id: &str, r: &Result<Vec<Out>, String>) -> Event {
+        match r {
+            Ok(outs) => Event::ToolEnd { id: id.into(), result: Some(Value::Array(out_blocks(outs))), error: None },
+            Err(e) => Event::ToolEnd { id: id.into(), result: None, error: Some(e.clone()) },
+        }
+    }
+}
+
+// ---------------------------------------------------------------------- turn handle, sink
+
+/// A running API turn. `approve` answers a `NeedsApproval` event.
+pub struct ApiTurn {
+    pub(crate) stop: Arc<AtomicBool>,
+    running: Arc<AtomicBool>,
+    approvals: Sender<(String, bool)>,
+}
+
+impl ApiTurn {
+    pub fn approve(&self, id: &str, ok: bool) {
+        let _ = self.approvals.send((id.to_string(), ok));
+    }
+
+    /// Runs `work(stop, approvals)` on a named thread; the turn counts as running until it returns.
+    pub fn spawn(name: &str, work: impl FnOnce(Arc<AtomicBool>, Receiver<(String, bool)>) + Send + 'static) -> Result<ApiTurn, String> {
+        let (approvals, approvals_rx) = channel();
+        let turn = ApiTurn { stop: Arc::new(AtomicBool::new(false)), running: Arc::new(AtomicBool::new(true)), approvals };
+        let (stop, running) = (turn.stop.clone(), turn.running.clone());
+        std::thread::Builder::new()
+            .name(name.into())
+            .spawn(move || {
+                work(stop, approvals_rx);
+                running.store(false, Ordering::SeqCst);
+            })
+            .map_err(|e| e.to_string())?;
+        Ok(turn)
+    }
+}
+
+impl Turn for ApiTurn {
+    /// The worker polls the flag every 100 ms and drops the connection.
+    fn stop(&mut self) {
+        self.stop.store(true, Ordering::SeqCst);
+    }
+    fn is_running(&self) -> bool {
+        self.running.load(Ordering::SeqCst)
+    }
+}
+
+/// Sends events; the turn's `TurnEnd` or `Error` is held back until `flush`, so the history is on
+/// disk before the app sees the end (it deletes or reopens the chat right then).
+pub struct Sink {
+    tx: Sender<Event>,
+    pub stop: Arc<AtomicBool>,
+    terminal: std::cell::RefCell<Option<Event>>,
+}
+
+impl Sink {
+    pub fn new(tx: Sender<Event>, stop: Arc<AtomicBool>) -> Self {
+        Self { tx, stop, terminal: Default::default() }
+    }
+
+    pub fn stopped(&self) -> bool {
+        self.stop.load(Ordering::SeqCst)
+    }
+
+    pub fn emit(&self, e: Event) {
+        if matches!(e, Event::TurnEnd { .. } | Event::Error(_)) {
+            self.terminal.borrow_mut().get_or_insert(e);
+            return;
+        }
+        if self.tx.send(e).is_err() {
+            self.stop.store(true, Ordering::SeqCst);
+        }
+    }
+
+    pub fn flush(&self) {
+        if let Some(e) = self.terminal.take() {
+            let _ = self.tx.send(e);
+        }
+    }
+}
+
+/// Messages only change in consistent steps, so this file is always replayable.
+pub fn persist(path: Option<&std::path::PathBuf>, messages: &[Value]) {
+    let Some(p) = path else { return };
+    if let Some(dir) = p.parent() {
+        let _ = std::fs::create_dir_all(dir);
+    }
+    let r = serde_json::to_vec(messages).map_err(|e| e.to_string()).and_then(|b| std::fs::write(p, b).map_err(|e| e.to_string()));
+    if let Err(e) = r {
+        log::warn!("chat history not saved: {e}");
+    }
+}
+
+/// Reads `chats/<id>.api.json`; a missing file is an empty history.
+pub fn load_history(path: Option<&std::path::PathBuf>) -> Result<Vec<Value>, String> {
+    match path.map(std::fs::read) {
+        Some(Ok(b)) => serde_json::from_slice(&b).map_err(|e| format!("chat history is unreadable: {e}")),
+        _ => Ok(vec![]),
+    }
+}
+
+// ---------------------------------------------------------------------- HTTP
+
+pub enum Halt {
+    Stopped,
+    /// An error event was already sent.
+    Reported,
+    Fail(String),
+}
+
+pub fn client() -> Result<reqwest::Client, String> {
+    reqwest::Client::builder().connect_timeout(CONNECT_TIMEOUT).read_timeout(READ_TIMEOUT).build().map_err(|e| format!("http client: {e}"))
+}
+
+/// Header names that carry the key; marked sensitive so they never show up in debug output.
+const SENSITIVE: [&str; 2] = ["x-api-key", "authorization"];
+
+/// POSTs `body`; on a non-2xx answer returns `Fail("<label> error <status>: <message>")`.
+/// Stop is polled every 100 ms, also while the error body is read.
+pub async fn post(stop: &AtomicBool, client: &reqwest::Client, url: &str, headers: Vec<(&'static str, String)>, body: &Value, label: &str) -> Result<reqwest::Response, Halt> {
+    let mut req = client.post(url).body(body.to_string());
+    for (k, v) in headers {
+        let mut hv = reqwest::header::HeaderValue::from_str(&v).map_err(|_| Halt::Fail(format!("invalid {k} header value")))?;
+        hv.set_sensitive(SENSITIVE.contains(&k));
+        req = req.header(k, hv);
+    }
+    let send = req.send();
+    tokio::pin!(send);
+    let mut resp = loop {
+        match tokio::time::timeout(POLL, &mut send).await {
+            Ok(r) => break r.map_err(|e| Halt::Fail(format!("request failed: {}", e.without_url())))?,
+            Err(_) if stop.load(Ordering::SeqCst) => return Err(Halt::Stopped),
+            Err(_) => {}
+        }
+    };
+    if resp.status().is_success() {
+        return Ok(resp);
+    }
+    let status = resp.status();
+    let mut bytes: Vec<u8> = vec![];
+    while bytes.len() < ERROR_BODY_MAX {
+        if stop.load(Ordering::SeqCst) {
+            return Err(Halt::Stopped);
+        }
+        match tokio::time::timeout(POLL, resp.chunk()).await {
+            Err(_) => {}
+            Ok(Ok(Some(c))) => bytes.extend_from_slice(&c),
+            Ok(_) => break,
+        }
+    }
+    let text = String::from_utf8_lossy(&bytes).into_owned();
+    let v = serde_json::from_str::<Value>(&text).ok();
+    // `{"error":{"message":..}}` (both formats), `{"error":"..."}` or `{"message":..}`.
+    let msg = v.as_ref().and_then(|v| v["error"]["message"].as_str().or_else(|| v["error"].as_str()).or_else(|| v["message"].as_str()).map(str::to_string));
+    Err(Halt::Fail(format!("{label} error {status}: {}", msg.unwrap_or(text))))
+}
+
+/// Feeds the response body to `feed` as UTF-8 text until it returns true (the reply is complete) or
+/// the body ends. Stop drops the connection.
+pub async fn read_stream(stop: &AtomicBool, mut resp: reqwest::Response, mut feed: impl FnMut(&str) -> bool) -> Result<(), Halt> {
+    let mut pending: Vec<u8> = vec![];
+    loop {
+        if stop.load(Ordering::SeqCst) {
+            return Err(Halt::Stopped);
+        }
+        let chunk = match tokio::time::timeout(POLL, resp.chunk()).await {
+            Err(_) => continue,
+            Ok(r) => r.map_err(|e| Halt::Fail(format!("stream error: {}", e.without_url())))?,
+        };
+        let Some(chunk) = chunk else { return Ok(()) };
+        pending.extend_from_slice(&chunk);
+        let valid = std::str::from_utf8(&pending).map_or_else(|e| e.valid_up_to(), str::len);
+        let text = String::from_utf8_lossy(&pending[..valid]).into_owned();
+        pending.drain(..valid);
+        if feed(&text) {
+            return Ok(());
+        }
+    }
+}
+
+/// Runs `fut` on a fresh current-thread runtime, as the workers do.
+pub fn block_on<F: std::future::Future<Output = ()>>(fut: F) -> Result<(), String> {
+    let rt = tokio::runtime::Builder::new_current_thread().enable_all().build().map_err(|e| format!("could not start the network runtime: {e}"))?;
+    rt.block_on(fut);
+    Ok(())
+}
+
+/// Replaces anything that looks like the key in an error message (servers sometimes echo it).
+pub fn redact(msg: &str, key: &str) -> String {
+    if key.len() < 8 { msg.to_string() } else { msg.replace(key, "[redacted]") }
+}
+
+/// A fake HTTP server for the loop tests.
+#[cfg(test)]
+pub mod test_support {
+    use serde_json::Value;
+    use std::io::{BufRead, BufReader, Read, Write};
+    use std::sync::{Arc, Mutex};
+
+    /// `(lowercased request headers, JSON body)` per request.
+    pub type Seen = Arc<Mutex<Vec<(Vec<String>, Value)>>>;
+
+    /// Serves one canned SSE response per connection, in order; records headers and body.
+    pub fn serve(responses: Vec<&'static str>) -> (String, Seen) {
+        let ok = "HTTP/1.1 200 OK\r\ncontent-type: text/event-stream\r\nconnection: close\r\n\r\n";
+        serve_raw(responses.into_iter().map(|r| format!("{ok}{r}")).collect())
+    }
+
+    pub fn serve_raw(responses: Vec<String>) -> (String, Seen) {
+        let l = std::net::TcpListener::bind("127.0.0.1:0").unwrap();
+        let url = format!("http://{}", l.local_addr().unwrap());
+        let seen: Seen = Arc::default();
+        let s = seen.clone();
+        std::thread::spawn(move || {
+            for resp in responses {
+                let (mut sock, _) = l.accept().unwrap();
+                let mut rd = BufReader::new(sock.try_clone().unwrap());
+                let (mut headers, mut len) = (vec![], 0usize);
+                loop {
+                    let mut line = String::new();
+                    rd.read_line(&mut line).unwrap();
+                    let line = line.trim_end().to_lowercase();
+                    if line.is_empty() {
+                        break;
+                    }
+                    if let Some(n) = line.strip_prefix("content-length:") {
+                        len = n.trim().parse().unwrap();
+                    }
+                    headers.push(line);
+                }
+                let mut body = vec![0; len];
+                rd.read_exact(&mut body).unwrap();
+                s.lock().unwrap().push((headers, serde_json::from_slice(&body).unwrap()));
+                let _ = sock.write_all(resp.as_bytes());
+            }
+        });
+        (url, seen)
+    }
+}
@@ -0,0 +1,409 @@
+//! Undoable annotation edits: each call is one history step.
+
+use super::Editor;
+use crate::history::Tx;
+use crate::model::annotation::{Annotation, AnnotationCategory, AnnotationTemplate, builtin_templates};
+use crate::variables::{Error, PAGE_TEMPLATE_KEY};
+
+impl Tx<'_> {
+    /// Add an annotation (its id is allocated here). Returns the id.
+    pub fn add_annotation(&mut self, mut a: Annotation) -> u64 {
+        self.snapshot_annotations();
+        a.id = self.doc.alloc_id().0;
+        if a.created == 0 {
+            a.created = crate::project::format::now_ms();
+        }
+        let id = a.id;
+        self.doc.annotations.push(a);
+        id
+    }
+
+    /// Add annotation copies (see `annotation::copies_for`) under fresh ids.
+    pub fn add_annotation_copies(&mut self, copies: Vec<Annotation>) {
+        for a in copies {
+            self.add_annotation(a);
+        }
+    }
+
+    /// Change an annotation in place; `id` and `target` stay as they were unless `f` sets them.
+    pub fn update_annotation(&mut self, id: u64, f: impl FnOnce(&mut Annotation)) -> bool {
+        if !self.doc.annotations.iter().any(|a| a.id == id) {
+            return false;
+        }
+        self.snapshot_annotations();
+        let a = self.doc.annotations.iter_mut().find(|a| a.id == id).unwrap();
+        f(a);
+        a.id = id;
+        true
+    }
+
+    pub fn delete_annotation(&mut self, id: u64) -> bool {
+        if !self.doc.annotations.iter().any(|a| a.id == id) {
+            return false;
+        }
+        self.snapshot_annotations();
+        self.doc.annotations.retain(|a| a.id != id);
+        true
+    }
+}
+
+impl Editor {
+    pub fn add_annotation(&mut self, a: Annotation) -> u64 {
+        self.edit("Add annotation", |tx| tx.add_annotation(a))
+    }
+
+    /// Update label, body, category, position or anchor of one annotation.
+    pub fn update_annotation(&mut self, id: u64, f: impl FnOnce(&mut Annotation)) -> bool {
+        self.edit("Edit annotation", |tx| tx.update_annotation(id, f))
+    }
+
+    pub fn delete_annotation(&mut self, id: u64) -> bool {
+        self.edit("Delete annotation", |tx| tx.delete_annotation(id))
+    }
+
+    /// Page `page`'s own template override, if set.
+    pub fn page_template_id(&self, page: usize) -> Option<&str> {
+        self.pages[page].modes.get(PAGE_TEMPLATE_KEY).map(String::as_str)
+    }
+
+    /// The template in effect on page `page`: its override, else the project default.
+    pub fn active_template(&self, page: usize) -> AnnotationTemplate {
+        self.design.active_template(self.page_template_id(page))
+    }
+
+    /// Set the project's default template (`None` = Product spec). Undoable.
+    pub fn set_default_template(&mut self, id: Option<&str>) -> Result<(), Error> {
+        if let Some(id) = id
+            && !self.design.templates().iter().any(|t| t.id == id)
+        {
+            return Err(Error::NotFound(id.into()));
+        }
+        self.edit_design("Set default annotation template", |d| {
+            d.annotation_template = id.map(String::from);
+            Ok(())
+        })
+        .map(|_| ())
+    }
+
+    /// Override the template on one page (`None` = follow the project default). Undoable.
+    pub fn set_page_template(&mut self, page: usize, id: Option<&str>) -> Result<(), Error> {
+        if let Some(id) = id
+            && !self.design.templates().iter().any(|t| t.id == id)
+        {
+            return Err(Error::NotFound(id.into()));
+        }
+        self.set_page_template_on(page, id);
+        Ok(())
+    }
+
+    /// Add a template, or replace the one with the same id. Undoable.
+    pub fn upsert_template(&mut self, t: AnnotationTemplate) -> Result<(), Error> {
+        self.edit_design("Edit annotation template", |d| {
+            let mut all = d.templates();
+            match all.iter_mut().find(|x| x.id == t.id) {
+                Some(x) => *x = t,
+                None => all.push(t),
+            }
+            d.annotation_templates = all;
+            Ok(())
+        })
+        .map(|_| ())
+    }
+
+    /// Delete a template (the last one stays). A default pointing at it goes back to Product spec.
+    pub fn delete_template(&mut self, id: &str) -> Result<(), Error> {
+        self.edit_design("Delete annotation template", |d| {
+            let mut all = d.templates();
+            if all.len() < 2 {
+                return Err(Error::LastMode);
+            }
+            let n = all.len();
+            all.retain(|t| t.id != id);
+            if all.len() == n {
+                return Err(Error::NotFound(id.into()));
+            }
+            d.annotation_templates = all;
+            if d.annotation_template.as_deref() == Some(id) {
+                d.annotation_template = None;
+            }
+            Ok(())
+        })
+        .map(|_| ())
+    }
+
+    /// Copy a template under a fresh id ("<name> copy"). Returns the new id. Undoable.
+    pub fn duplicate_template(&mut self, id: &str) -> Result<String, Error> {
+        self.edit_design("Duplicate annotation template", |d| {
+            let mut all = d.templates();
+            let src = all.iter().find(|t| t.id == id).ok_or_else(|| Error::NotFound(id.into()))?;
+            let mut copy = src.clone();
+            let mut n = 1;
+            while all.iter().any(|t| t.id == copy.id) {
+                n += 1;
+                copy.id = format!("{id}-{n}");
+            }
+            copy.name = format!("{} copy", src.name);
+            let new = copy.id.clone();
+            all.push(copy);
+            d.annotation_templates = all;
+            Ok(new)
+        })
+        .map(|(id, _)| id)
+    }
+
+    /// Save an edited template together with the category list it was edited against. A changed
+    /// category key is renamed in every template. One undo step per page. Duplicate keys are refused.
+    pub fn save_template(&mut self, t: AnnotationTemplate, cats: Vec<AnnotationCategory>) -> Result<(), Error> {
+        self.edit_design("Edit annotation template", |d| {
+            let old = d.categories();
+            for (i, c) in cats.iter().enumerate() {
+                if cats[..i].iter().any(|o| o.key().eq_ignore_ascii_case(c.key())) {
+                    return Err(Error::Duplicate(c.key().into()));
+                }
+            }
+            let renames: Vec<(String, String)> = cats
+                .iter()
+                .filter_map(|c| old.iter().find(|o| o.id == c.id).map(|o| (o.key().to_string(), c.key().to_string())))
+                .filter(|(a, b)| a != b)
+                .collect();
+            let rename = |t: &mut AnnotationTemplate| {
+                for tc in &mut t.categories {
+                    if let Some((_, to)) = renames.iter().find(|(from, _)| *from == tc.key) {
+                        tc.key.clone_from(to);
+                    }
+                }
+            };
+            let mut all = d.templates();
+            all.iter_mut().for_each(rename);
+            let mut t = t;
+            rename(&mut t);
+            match all.iter_mut().find(|x| x.id == t.id) {
+                Some(x) => *x = t,
+                None => all.push(t),
+            }
+            d.annotation_templates = all;
+            d.annotation_categories = cats;
+            Ok(())
+        })
+        .map(|_| ())
+    }
+
+    /// Put a built-in template back to its original content. Errors for a custom template.
+    pub fn reset_template(&mut self, id: &str) -> Result<(), Error> {
+        let original = builtin_templates()
+            .into_iter()
+            .find(|t| t.id == id)
+            .ok_or_else(|| Error::NotFound(id.into()))?;
+        self.upsert_template(original)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::geom::{Rect, V2, v2};
+    use crate::model::annotation::{self, Anchor, Side};
+    use crate::model::{Node, NodeId, NodeKind};
+
+    fn frame(e: &mut Editor, r: Rect) -> NodeId {
+        e.add_node(Node::new(NodeId(0), NodeKind::Frame { clip: true }, r), None)
+    }
+
+    fn child(e: &mut Editor, parent: NodeId, r: Rect) -> NodeId {
+        e.add_node(Node::new(NodeId(0), NodeKind::Rect, r), Some(parent))
+    }
+
+    #[test]
+    fn add_update_delete_undo_one_step_each() {
+        let mut e = Editor::default();
+        let f = frame(&mut e, Rect::new(0.0, 0.0, 100.0, 100.0));
+        let base = e.doc.clone();
+        let mut a = Annotation::new(Some(f), "Label", "data");
+        a.position = v2(120.0, 0.0);
+        let id = e.add_annotation(a);
+        let added = e.doc.clone();
+        assert_eq!(e.doc.annotations.len(), 1);
+        assert!(e.update_annotation(id, |a| {
+            a.label = "New".into();
+            a.body = "text".into();
+            a.category = "content".into();
+            a.position = v2(5.0, 6.0);
+            a.anchor = Anchor { side: Side::Left, t: 0.25 };
+        }));
+        let updated = e.doc.clone();
+        assert_eq!(updated.annotations[0].label, "New");
+        assert!(e.delete_annotation(id));
+        assert!(e.doc.annotations.is_empty());
+        assert!(!e.delete_annotation(id), "missing id is a no-op");
+        e.undo();
+        assert_eq!(e.doc, updated);
+        e.undo();
+        assert_eq!(e.doc, added);
+        e.undo();
+        assert_eq!(e.doc, base);
+        e.redo();
+        assert_eq!(e.doc, added);
+    }
+
+    #[test]
+    fn move_and_resize_target_keep_anchor_and_card() {
+        let mut e = Editor::default();
+        let f = frame(&mut e, Rect::new(100.0, 100.0, 400.0, 400.0));
+        let c = child(&mut e, f, Rect::new(10.0, 20.0, 100.0, 50.0));
+        let mut a = Annotation::new(Some(c), "x", "data");
+        a.anchor = Anchor { side: Side::Right, t: 0.5 };
+        a.position = v2(150.0, -10.0);
+        let id = e.add_annotation(a);
+        let a0 = e.doc.annotations[0].clone();
+        assert_eq!(annotation::anchor_world(&e.doc, &a0), v2(210.0, 145.0));
+        assert_eq!(annotation::card_world(&e.doc, &a0), v2(260.0, 110.0));
+        e.edit("move", |tx| tx.node_mut(c).unwrap().rect = Rect::new(30.0, 40.0, 200.0, 100.0));
+        let a1 = e.doc.annotations[0].clone();
+        assert_eq!(a1, a0, "annotation itself untouched");
+        assert_eq!(annotation::anchor_world(&e.doc, &a1), v2(330.0, 190.0));
+        assert_eq!(annotation::card_world(&e.doc, &a1), v2(280.0, 130.0));
+        e.edit("move frame", |tx| tx.node_mut(f).unwrap().rect.x += 1000.0);
+        assert_eq!(annotation::anchor_world(&e.doc, &e.doc.annotations[0]), v2(1330.0, 190.0));
+        let _ = id;
+    }
+
+    #[test]
+    fn deleting_target_detaches_and_undo_reattaches() {
+        let mut e = Editor::default();
+        let f = frame(&mut e, Rect::new(100.0, 100.0, 400.0, 400.0));
+        let c = child(&mut e, f, Rect::new(10.0, 20.0, 100.0, 50.0));
+        let mut a = Annotation::new(Some(c), "x", "data");
+        a.anchor = Anchor { side: Side::Bottom, t: 1.0 };
+        a.position = v2(150.0, 0.0);
+        e.add_annotation(a);
+        let before = e.doc.clone();
+        let (anchor, card) = {
+            let a = &e.doc.annotations[0];
+            (annotation::anchor_world(&e.doc, a), annotation::card_world(&e.doc, a))
+        };
+        e.edit("Delete", |tx| tx.remove(f));
+        let a = &e.doc.annotations[0];
+        assert!(a.detached && a.target.is_none());
+        assert_eq!(a.point, Some(anchor));
+        assert_eq!(annotation::anchor_world(&e.doc, a), anchor);
+        assert_eq!(annotation::card_world(&e.doc, a), card);
+        e.undo();
+        assert_eq!(e.doc, before);
+    }
+
+    #[test]
+    fn auto_position_sits_right_of_frame_and_stacks() {
+        let mut e = Editor::default();
+        let f = frame(&mut e, Rect::new(100.0, 100.0, 400.0, 400.0));
+        let c = child(&mut e, f, Rect::new(10.0, 20.0, 100.0, 50.0));
+        let p1 = annotation::auto_position(&e.doc, c);
+        let mut a = Annotation::new(Some(c), "1", "rule");
+        a.position = p1;
+        e.add_annotation(a);
+        let w1 = annotation::card_world(&e.doc, &e.doc.annotations[0]);
+        assert_eq!(w1, v2(524.0, 120.0));
+        let p2 = annotation::auto_position(&e.doc, c);
+        let w2 = v2(110.0, 120.0) + p2;
+        assert_eq!(w2.x, w1.x);
+        assert!(w2.y >= w1.y + annotation::CARD_H, "stacked below, no overlap");
+    }
+
+    #[test]
+    fn numbering_is_per_frame_in_reading_order() {
+        let mut e = Editor::default();
+        let f1 = frame(&mut e, Rect::new(0.0, 0.0, 300.0, 300.0));
+        let f2 = frame(&mut e, Rect::new(500.0, 0.0, 300.0, 300.0));
+        let low = child(&mut e, f1, Rect::new(10.0, 200.0, 20.0, 20.0));
+        let right = child(&mut e, f1, Rect::new(200.0, 10.0, 20.0, 20.0));
+        let left = child(&mut e, f1, Rect::new(10.0, 10.0, 20.0, 20.0));
+        let other = child(&mut e, f2, Rect::new(10.0, 10.0, 20.0, 20.0));
+        let mut ids = Vec::new();
+        for t in [Some(low), Some(right), Some(left), Some(other), None] {
+            ids.push(e.add_annotation(Annotation::new(t, "n", "data")));
+        }
+        let n = annotation::numbers(&e.doc);
+        assert_eq!(n[&ids[2]], (Some(f1), 1));
+        assert_eq!(n[&ids[1]], (Some(f1), 2));
+        assert_eq!(n[&ids[0]], (Some(f1), 3));
+        assert_eq!(n[&ids[3]], (Some(f2), 1));
+        assert_eq!(n[&ids[4]], (None, 1));
+    }
+
+    #[test]
+    fn paste_of_a_frame_copies_its_annotations() {
+        let mut e = Editor::default();
+        let f = frame(&mut e, Rect::new(0.0, 0.0, 200.0, 200.0));
+        let c = child(&mut e, f, Rect::new(10.0, 10.0, 20.0, 20.0));
+        e.add_annotation(Annotation::new(Some(c), "on child", "data"));
+        e.add_annotation(Annotation::new(Some(f), "on frame", "content"));
+        e.add_annotation(Annotation::new(None, "loose", "content"));
+        e.select(vec![f]);
+        e.copy_internal();
+        e.paste(V2::ZERO);
+        assert_eq!(e.doc.annotations.len(), 5);
+        let copy = e.selection[0];
+        let copy_child = e.doc.get(copy).unwrap().children[0];
+        let mut ids: Vec<u64> = e.doc.annotations.iter().map(|a| a.id).collect();
+        ids.sort();
+        ids.dedup();
+        assert_eq!(ids.len(), 5, "fresh ids");
+        let on = |t| e.doc.annotations.iter().filter(|a| a.target == Some(t)).count();
+        assert_eq!((on(f), on(c), on(copy), on(copy_child)), (1, 1, 1, 1));
+        e.undo();
+        assert_eq!(e.doc.annotations.len(), 3);
+    }
+
+    #[test]
+    fn restore_snapshot_restores_annotations_in_one_undo() {
+        let mut e = Editor::default();
+        let f = frame(&mut e, Rect::new(0.0, 0.0, 100.0, 100.0));
+        e.add_annotation(Annotation::new(Some(f), "old", "data"));
+        let snap = e.doc.clone();
+        e.delete_annotation(snap.annotations[0].id);
+        e.add_annotation(Annotation::new(Some(f), "agent", "rule"));
+        let changed = e.doc.clone();
+        e.restore_snapshot(&snap);
+        assert_eq!(e.doc.annotations, snap.annotations, "target kept, not detached");
+        e.undo();
+        assert_eq!(e.doc.annotations, changed.annotations);
+    }
+
+    #[test]
+    fn revert_to_snapshot_without_annotations_removes_them_and_undo_restores() {
+        let mut e = Editor::default();
+        let f = frame(&mut e, Rect::new(0.0, 0.0, 100.0, 100.0));
+        let snap = e.doc.clone();
+        e.add_annotation(Annotation::new(Some(f), "agent", "rule"));
+        e.restore_snapshot(&snap);
+        assert!(e.doc.annotations.is_empty());
+        e.undo();
+        assert_eq!(e.doc.annotations.len(), 1);
+        assert_eq!(e.doc.annotations[0].target, Some(f));
+    }
+
+    #[test]
+    fn save_template_renames_category_key_everywhere_in_one_undo() {
+        let mut e = Editor::default();
+        let mut cats = e.design.categories();
+        cats[0].key = "policy".into();
+        let mut t = e.design.template_by_ref("product-spec").unwrap();
+        t.name = "Spec".into();
+        let before = e.design.clone();
+        let undo_len = e.history.undo_len();
+        e.save_template(t, cats.clone()).unwrap();
+        assert_eq!(e.history.undo_len(), undo_len + 1);
+        for t in e.design.templates() {
+            assert!(t.categories.iter().all(|c| c.key != "rule"), "{}", t.name);
+        }
+        assert!(e.active_template(0).enabled("policy").is_some());
+        assert!(e.design.category_by_key("policy").is_some());
+        let mut dup = cats.clone();
+        dup[1].key = "POLICY".into();
+        let t = e.design.template_by_ref("minimal").unwrap();
+        let now = e.design.clone();
+        assert!(e.save_template(t, dup).is_err());
+        assert_eq!(e.design, now);
+        e.undo();
+        assert_eq!(e.design, before);
+    }
+}
@@ -12,9 +12,13 @@ pub enum UiEvent {
    TogglePalette,
    Rename(NodeId),
    ToggleUi,
+    ToggleChat,
    ToggleHelp,
    ToggleGrid,
+    ToggleAnnotations,
    OpenVariables,
+    /// Open the New annotation popover on this layer.
+    Annotate(NodeId),
 }

 impl Editor {
@@ -61,7 +61,11 @@ impl Editor {
        // A project that never went through the session (no design.json yet) starts from what
        // its first page already holds.
        if self.design.collections.is_empty() {
+            let old = std::mem::take(&mut self.design);
            self.design = variables::migrate_from_document(self.page_doc(0));
+            self.design.annotation_categories = old.annotation_categories;
+            self.design.annotation_templates = old.annotation_templates;
+            self.design.annotation_template = old.annotation_template;
        }
        let before = self.design.clone();
        let mut next = before.clone();
@@ -208,6 +212,26 @@ impl Editor {
        Ok(n.values().sum())
    }

+    /// Set (or clear, with `None`) page `page`'s annotation template override. One undo step.
+    pub fn set_page_template_on(&mut self, page: usize, template: Option<&str>) {
+        let old = self.pages[page].modes.clone();
+        let mut modes = old.clone();
+        match template {
+            Some(t) => modes.insert(variables::PAGE_TEMPLATE_KEY.into(), t.into()),
+            None => modes.remove(variables::PAGE_TEMPLATE_KEY),
+        };
+        if modes == old {
+            return;
+        }
+        let cache = self.design.cache_for(&modes);
+        self.with_page(page, |ed| {
+            ed.rebuild_cache("Set annotation template", &cache, &BTreeMap::new(), None, None, |rec| {
+                rec.page_modes = Some((old, modes.clone()));
+            }, true)
+        });
+        self.pages[page].modes = modes;
+    }
+
    /// Bind `field` of `ids` to variable `css` (`None` detaches: the current value stays, the
    /// binding goes). The value applies at once. One undo step. On an instance the field becomes
    /// an override.
@@ -2,6 +2,7 @@
 //!
 //! It consumes platform-agnostic [`InputEvent`]s, so every interaction can be scripted in tests.

+pub mod annotations;
 pub mod commands;
 pub mod design;
 pub mod hit;
@@ -43,10 +44,11 @@ pub enum Tool {
    Pencil,
    Eraser,
    Laser,
+    Annotate,
 }

 impl Tool {
-    pub const ALL: [Tool; 16] = [
+    pub const ALL: [Tool; 17] = [
        Tool::Select,
        Tool::Hand,
        Tool::Frame,
@@ -63,6 +65,7 @@ impl Tool {
        Tool::Pencil,
        Tool::Eraser,
        Tool::Laser,
+        Tool::Annotate,
    ];
    pub fn label(self) -> &'static str {
        match self {
@@ -82,6 +85,7 @@ impl Tool {
            Tool::Pencil => "Pencil",
            Tool::Eraser => "Eraser",
            Tool::Laser => "Laser pointer",
+            Tool::Annotate => "Annotate",
        }
    }
    pub fn shortcut(self) -> &'static str {
@@ -102,6 +106,7 @@ impl Tool {
            Tool::Pencil => "⇧P",
            Tool::Eraser => "E",
            Tool::Laser => "K",
+            Tool::Annotate => "N",
        }
    }
 }
@@ -250,6 +255,8 @@ pub struct Editor {
    pub project_stamp: u64,
    /// Fit the camera to the content once the real viewport size is known.
    pub pending_fit: bool,
+    /// No window: `viewport` is a stand-in, so cameras are not saved (the app fits on open).
+    pub headless: bool,
    /// Pages of the open project; the active one's content is `doc`/`history`/`camera`.
    pub pages: Vec<PageSlot>,
    pub active_page: usize,
@@ -343,6 +350,7 @@ impl Editor {
            doc_stamp: next_stamp(),
            project_stamp: next_stamp(),
            pending_fit: false,
+            headless: false,
            pages: vec![PageSlot::new(&name)],
            active_page: 0,
            page_groups: BTreeMap::new(),
@@ -493,6 +501,7 @@ impl Editor {
    pub fn load(&mut self, doc: Document, camera: Option<Camera>, path: Option<PathBuf>) {
        *self = Editor {
            viewport: self.viewport,
+            headless: self.headless,
            ink_width: self.ink_width,
            ink_smoothing: self.ink_smoothing,
            ink_color: self.ink_color,
@@ -806,6 +815,13 @@ impl Editor {
            }
            Tool::Arrow => self.arrow_down(if self.snapping { world.round() } else { world }),
            Tool::Sticky => self.sticky_down(world),
+            Tool::Annotate => {
+                self.end_text_edit();
+                if let Some(id) = hit::hit_test(&self.doc, world, self.camera.zoom) {
+                    self.selection = vec![id];
+                    self.ui_events.push(commands::UiEvent::Annotate(id));
+                }
+            }
            Tool::Laser => {
                self.laser_point(world, time_ms);
                self.gesture = Gesture::Laser;
@@ -2021,8 +2037,10 @@ impl Editor {
                }
            }
            A::ToggleUi => self.ui_events.push(commands::UiEvent::ToggleUi),
+            A::ToggleChat => self.ui_events.push(commands::UiEvent::ToggleChat),
            A::ToggleHelp => self.ui_events.push(commands::UiEvent::ToggleHelp),
            A::ToggleGrid => self.ui_events.push(commands::UiEvent::ToggleGrid),
+            A::ToggleAnnotations => self.ui_events.push(commands::UiEvent::ToggleAnnotations),
            A::OpenVariables => self.ui_events.push(commands::UiEvent::OpenVariables),
            A::SelectNext => self.select_sibling(true),
            A::SelectPrev => self.select_sibling(false),
@@ -2447,6 +2465,10 @@ pub fn insert_subtrees_tx(
    for id in map.values() {
        crate::editor::whiteboard::update_connector(tx, *id);
    }
+    if same_page {
+        let copies = crate::model::annotation::copies_for(&tx.doc().annotations.clone(), &map);
+        tx.add_annotation_copies(copies);
+    }
    new_roots
 }

@@ -421,6 +421,7 @@ impl Editor {
            let s = slot.stash.as_ref().expect("inactive page has a stash");
            (s.doc.clone(), (!s.needs_fit).then_some(s.camera))
        };
+        let camera = camera.filter(|_| !self.headless);
        PageData {
            id: slot.id.clone(),
            name: slot.name.clone(),
@@ -635,6 +636,8 @@ fn replace_content(tx: &mut crate::history::Tx, snap: &Document) {
    for root in tx.doc().root.clone() {
        tx.remove(root);
    }
+    tx.snapshot_annotations();
+    tx.doc.annotations.clone_from(&snap.annotations);
    for root in snap.root.clone() {
        for (i, id) in snap.subtree(root).into_iter().enumerate() {
            let Some(node) = snap.get(id).cloned() else {
@@ -57,8 +57,10 @@ pub enum Action {
    CommandPalette,
    Rename,
    ToggleUi,
+    ToggleChat,
    ToggleHelp,
    ToggleGrid,
+    ToggleAnnotations,
    OpenVariables,
    SelectNext,
    SelectPrev,
@@ -134,6 +136,7 @@ fn bindings() -> Vec<(Key, Chord, Action, &'static str)> {
        (Char('l'), SHIFT, A::Tool(Tool::Arrow), "Arrow tool"),
        (Char('s'), PLAIN, A::Tool(Tool::Sticky), "Sticky note"),
        (Char('k'), PLAIN, A::Tool(Tool::Laser), "Laser pointer"),
+        (Char('n'), PLAIN, A::Tool(Tool::Annotate), "Annotate tool"),
        (Char('1'), PLAIN, A::Tool(Tool::Select), "Select tool"),
        (Char('2'), PLAIN, A::Tool(Tool::Rect), "Rectangle tool"),
        (Char('3'), PLAIN, A::Tool(Tool::Diamond), "Diamond tool"),
@@ -158,6 +161,7 @@ fn bindings() -> Vec<(Key, Chord, Action, &'static str)> {
        (Char('k'), CMD, A::CommandPalette, "Command palette"),
        (Char('p'), CMD_ALT, A::ExportPdf, "Export PDF"),
        (Char('c'), CMD_SHIFT, A::CopyAsPng, "Copy as PNG"),
+        (Char('j'), CMD, A::ToggleChat, "Design / Chat mode"),
        (Char('c'), CMD_ALT_SHIFT, A::CopyAsSvg, "Copy as SVG"),
        (Char('/'), CMD_SHIFT, A::CommandPalette, "Command palette"),
        (Char('r'), CMD, A::Rename, "Rename layer"),
@@ -165,6 +169,8 @@ fn bindings() -> Vec<(Key, Chord, Action, &'static str)> {
        (Char('/'), CMD, A::ToggleHelp, "Keyboard shortcuts"),
        (Char('?'), SHIFT, A::ToggleHelp, "Keyboard shortcuts"),
        (Char('\''), CMD_SHIFT, A::ToggleGrid, "Show / hide dot grid"),
+        // Shift+A is Add auto layout, so annotations take Cmd+Shift+A.
+        (Char('a'), CMD_SHIFT, A::ToggleAnnotations, "Cycle annotations: full, badges, hidden"),
        // Cmd+Alt+V is taken by Paste properties.
        (Char('v'), CMD_ALT_SHIFT, A::OpenVariables, "Variables"),
        (Tab, PLAIN, A::SelectNext, "Select next sibling"),
@@ -422,8 +428,10 @@ pub fn category(a: Action) -> &'static str {
        | A::ZoomSelection
        | A::ToggleSnapping
        | A::ToggleGrid
+        | A::ToggleAnnotations
        | A::OpenVariables
        | A::ToggleUi
+        | A::ToggleChat
        | A::ToggleHelp
        | A::NextPage
        | A::PrevPage => "View",
@@ -605,7 +613,9 @@ pub fn menus() -> Vec<(&'static str, Vec<MenuEntry>)> {
                S,
                I("Snapping", A::ToggleSnapping),
                I("Dot Grid", A::ToggleGrid),
+                I("Annotations", A::ToggleAnnotations),
                I("Show/Hide UI", A::ToggleUi),
+                I("Design / Chat Mode", A::ToggleChat),
                I("Keyboard Shortcuts", A::ToggleHelp),
            ],
        ),
@@ -5,6 +5,7 @@
 //! and pushes a [`Change`] that can be applied in either direction.

 use crate::geom::V2;
+use crate::model::annotation::{self, Annotation};
 use crate::model::{Color, Document, Node, NodeId, VarState};
 use crate::variables::{Cache, DesignSystem, PageModes};
 use std::collections::{BTreeMap, BTreeSet, HashMap};
@@ -28,6 +29,8 @@ pub struct Change {
    design: Option<(Box<DesignSystem>, Box<DesignSystem>)>,
    /// The page's active mode per collection before/after (`Editor::set_page_mode`).
    page_modes: Option<(PageModes, PageModes)>,
+    /// The page's annotations before/after.
+    annotations: Option<(Vec<Annotation>, Vec<Annotation>)>,
    next_id: (u64, u64),
    coalesce_key: Option<String>,
 }
@@ -84,6 +87,9 @@ impl Change {
        if let Some((before, after)) = &self.variables {
            doc.restore_vars(if forward { after } else { before });
        }
+        if let Some((before, after)) = &self.annotations {
+            doc.annotations = if forward { after } else { before }.clone();
+        }
        doc.next_id = if forward {
            self.next_id.1
        } else {
@@ -102,6 +108,7 @@ pub struct Recording {
    variables_before: Option<VarState>,
    pub(crate) design: Option<(DesignSystem, DesignSystem)>,
    pub(crate) page_modes: Option<(PageModes, PageModes)>,
+    annotations_before: Option<Vec<Annotation>>,
    next_id_before: u64,
 }

@@ -447,11 +454,29 @@ impl<'a> Tx<'a> {
        self.doc.nodes.insert(node.id, node);
    }

-    /// Remove a node and its subtree.
+    pub(crate) fn snapshot_annotations(&mut self) {
+        if self.rec.annotations_before.is_none() {
+            self.rec.annotations_before = Some(self.doc.annotations.clone());
+        }
+    }
+
+    /// Remove a node and its subtree. Annotations on it stay, detached where they were.
    pub fn remove(&mut self, id: NodeId) {
        let Some(parent) = self.doc.get(id).map(|n| n.parent) else {
            return;
        };
+        let gone = self.doc.subtree(id);
+        if self.doc.annotations.iter().any(|a| a.target.is_some_and(|t| gone.contains(&t))) {
+            self.snapshot_annotations();
+            let mut list = std::mem::take(&mut self.doc.annotations);
+            for a in &mut list {
+                if a.target.is_some_and(|t| gone.contains(&t)) {
+                    let (point, card) = (annotation::anchor_world(self.doc, a), annotation::card_world(self.doc, a));
+                    (a.target, a.point, a.position, a.detached) = (None, Some(point), card, true);
+                }
+            }
+            self.doc.annotations = list;
+        }
        self.touch_parent_list(parent);
        if let Some(list) = self.doc.children_mut(parent) {
            list.retain(|c| *c != id);
@@ -533,7 +558,12 @@ impl History {
            .filter(|(b, a)| b != a)
            .map(|(b, a)| (Box::new(b), Box::new(a)));
        let page_modes = rec.page_modes.filter(|(b, a)| b != a);
+        let annotations = rec
+            .annotations_before
+            .filter(|b| *b != doc.annotations)
+            .map(|b| (b, doc.annotations.clone()));
        if entries.is_empty()
+            && annotations.is_none()
            && root.is_none()
            && variables.is_none()
            && design.is_none()
@@ -548,6 +578,7 @@ impl History {
            variables,
            design,
            page_modes,
+            annotations,
            next_id: (rec.next_id_before, doc.next_id),
            coalesce_key,
        };
@@ -645,6 +676,11 @@ fn merge(older: &mut Change, newer: Change) {
        (m @ None, Some(nm)) => *m = Some(nm),
        _ => {}
    }
+    match (&mut older.annotations, newer.annotations) {
+        (Some((_, after)), Some((_, new_after))) => *after = new_after,
+        (a @ None, Some(na)) => *a = Some(na),
+        _ => {}
+    }
    older.next_id.1 = newer.next_id.1;
 }

@@ -3,6 +3,7 @@
 #[cfg(not(target_arch = "wasm32"))]
 pub mod app;
 pub mod assets;
+pub mod chat;
 #[cfg(not(target_arch = "wasm32"))]
 pub mod cli;
 pub mod connector;
@@ -10,6 +10,7 @@ use crate::editor::Editor;
 use crate::model::{Document, Node, NodeId, Source};
 use crate::project::{Project, Store};
 use crate::variables::{self, Collection, EnabledLibrary, PageModes, Value, stable_id};
+#[cfg(not(target_arch = "wasm32"))]
 use base64::Engine;
 use serde::{Deserialize, Serialize};
 use std::cell::Cell;
@@ -19,6 +20,7 @@ use std::path::{Path, PathBuf};
 pub const LIBRARY_FILE: &str = "library.json";
 pub const LIBRARIES_DIR: &str = "libraries";
 /// Longest side of a component preview, in px.
+#[cfg(not(target_arch = "wasm32"))]
 const PREVIEW_PX: f64 = 256.0;
 /// Node ids stay below 2^53 so they survive a JSON round trip in any reader.
 const ID_MASK: u64 = (1 << 53) - 1;
@@ -18,7 +18,7 @@ USAGE:
  papercraft PROJECT_DIR                     open a project folder
  papercraft FILE.papercraft                 open a PaperCraft document (not autosaved)
  papercraft --demo                          open the app with a sample board
-  papercraft --screenshot OUT.png [--home | PROJECT|FILE|--demo] [--size WxH] [--scale S]
+  papercraft --screenshot OUT.png [--home | PROJECT|FILE|--demo] [--size WxH] [--scale S] [--chat]
                                           render the full UI headlessly to a PNG
  papercraft --export-png OUT.png PROJECT|FILE [--page N] [--scale S] [--transparent]
  papercraft --export-svg OUT.svg PROJECT|FILE [--page N]
@@ -126,6 +126,20 @@ fn run(args: Vec<String>) -> Result<(), String> {
    if let Some(out) = value("--screenshot") {
        let mut ed = load_editor(input, flag("--demo"))?;
        let mut st = UiState::default();
+        if flag("--chat") {
+            st.chat_mode = true;
+            st.project_dir = input.map(std::path::PathBuf::from).filter(|p| p.is_dir());
+            // As if the project was already seen, so `draw` keeps Chat mode on.
+            st.chat.project.clone_from(&st.project_dir);
+            st.chat.picker_open = flag("--chat-picker");
+            if let Some(dir) = &st.project_dir {
+                st.runs = papercraft::runs::list(dir);
+                st.runs_key.clone_from(&st.project_dir);
+            }
+        }
+        if flag("--dark") {
+            papercraft::theme::apply_choice(&egui::Context::default(), papercraft::theme::Choice::Dark);
+        }
        if flag("--home") {
            let store = Store::open(Store::default_root()).map_err(|e| e.to_string())?;
            st.home = Some(HomeView::load(&store, papercraft::project::now_ms()));
@@ -1174,10 +1174,55 @@ pub fn to_egui(doc: &Document, root: NodeId) -> String {
    out
 }

+pub(crate) fn annotation_comments(
+    doc: &Document,
+    root: NodeId,
+    categories: &[crate::model::annotation::AnnotationCategory],
+) -> String {
+    let ids = doc.subtree(root);
+    let numbers = crate::model::annotation::numbers(doc);
+    let mut notes: Vec<_> = doc
+        .annotations
+        .iter()
+        .filter(|a| a.target.is_some_and(|id| ids.contains(&id)))
+        .collect();
+    notes.sort_by_key(|a| (numbers[&a.id].0.map(|id| id.0), numbers[&a.id].1));
+    let mut out = String::new();
+    for note in notes {
+        let category = categories
+            .iter()
+            .find(|c| c.id == note.category)
+            .map(|c| c.name.as_str())
+            .unwrap_or(&note.category);
+        out.push_str(&format!(
+            "// {} {category}: {}\n",
+            numbers[&note.id].1, note.label
+        ));
+        for line in note.body.lines() {
+            out.push_str(&format!("// {line}\n"));
+        }
+    }
+    out
+}
+
 /// Generate code for `root` in the requested `target` format (`tailwind`/`jsx`, `react`/`tsx`,
 /// `angular`/`ng`, `html`/`css`, or `egui`/`rust`).
 pub fn code_for_target(doc: &Document, root: NodeId, target: &str) -> Result<String, String> {
-    match target.trim().to_ascii_lowercase().as_str() {
+    code_for_target_with_categories(
+        doc,
+        root,
+        target,
+        &crate::model::annotation::default_categories(),
+    )
+}
+
+pub(crate) fn code_for_target_with_categories(
+    doc: &Document,
+    root: NodeId,
+    target: &str,
+    categories: &[crate::model::annotation::AnnotationCategory],
+) -> Result<String, String> {
+    let code = match target.trim().to_ascii_lowercase().as_str() {
        "tailwind" | "jsx" => Ok(to_tailwind_jsx(doc, root)),
        "react" | "tsx" => Ok(to_react_tsx(doc, root)),
        "angular" | "ng" => Ok(to_angular(doc, root)),
@@ -1186,7 +1231,11 @@ pub fn code_for_target(doc: &Document, root: NodeId, target: &str) -> Result<Str
        other => Err(format!(
            "unknown target `{other}` (expected react, tailwind, angular, html, or egui)"
        )),
-    }
+    }?;
+    Ok(format!(
+        "{}{code}",
+        annotation_comments(doc, root, categories)
+    ))
 }

 fn sizing_name(s: Sizing) -> &'static str {
@@ -1560,10 +1609,17 @@ fn build_spec_tree(

 /// Build the deterministic AI Layout & Enforcement Spec JSON for `root` and `target`.
 pub fn to_ai_spec(doc: &Document, root: NodeId, target: &str) -> Result<Value, String> {
+    to_ai_spec_with_categories(doc, root, target, &crate::model::annotation::default_categories())
+}
+
+pub(crate) fn to_ai_spec_with_categories(
+    doc: &Document, root: NodeId, target: &str,
+    categories: &[crate::model::annotation::AnnotationCategory],
+) -> Result<Value, String> {
    let Some(root_node) = doc.get(root) else {
        return Err(format!("no node #{id}", id = root.0));
    };
-    let reference_code = code_for_target(doc, root, target)?;
+    let reference_code = code_for_target_with_categories(doc, root, target, categories)?;

    let mut components = Vec::new();
    let mut rules = Vec::new();
@@ -1635,6 +1691,7 @@ pub fn to_ai_spec(doc: &Document, root: NodeId, target: &str) -> Result<Value, S
        "componentDefinitions": definitions,
        "layoutTree": layout_tree,
        "enforcementRules": rules,
+        "annotations": annotation_comments(doc, root, categories).lines().collect::<Vec<_>>(),
        "referenceCode": reference_code,
    }))
 }
@@ -1713,7 +1770,14 @@ fn format_hierarchy_md(node: &Value, depth: usize, out: &mut String) {

 /// Format the AI Layout & Enforcement Spec as a structured Markdown document.
 pub fn to_ai_spec_markdown(doc: &Document, root: NodeId, target: &str) -> Result<String, String> {
-    let spec = to_ai_spec(doc, root, target)?;
+    to_ai_spec_markdown_with_categories(doc, root, target, &crate::model::annotation::default_categories())
+}
+
+pub(crate) fn to_ai_spec_markdown_with_categories(
+    doc: &Document, root: NodeId, target: &str,
+    categories: &[crate::model::annotation::AnnotationCategory],
+) -> Result<String, String> {
+    let spec = to_ai_spec_with_categories(doc, root, target, categories)?;
    let name = spec["name"].as_str().unwrap_or("Frame");
    let mut md = format!("# AI UI Implementation Spec: {name} ({target})\n\n");

@@ -402,11 +402,21 @@ pub struct PageDiff {
    pub groups: Vec<FrameGroup>,
    /// Variable, mode, active-mode and token changes, as `name: value` pairs.
    pub variables: Vec<PropChange>,
+    /// Added, removed and edited notes, paired by annotation id; each counts once like a variable.
+    pub annotations: Vec<AnnotationDiff>,
+}
+
+/// One note row in a [`PageDiff`]: `status` is "added", "removed" or "modified".
+#[derive(Debug, Clone, PartialEq, Serialize)]
+pub struct AnnotationDiff {
+    pub id: u64,
+    pub status: &'static str,
+    pub label: String,
 }

 impl PageDiff {
    pub fn is_empty(&self) -> bool {
-        self.groups.is_empty() && self.variables.is_empty()
+        self.groups.is_empty() && self.variables.is_empty() && self.annotations.is_empty()
    }
 }

@@ -594,6 +604,7 @@ pub fn diff_pages(before: &Document, after: &Document) -> PageDiff {
        modified: 0,
        groups: Vec::new(),
        variables: Vec::new(),
+        annotations: Vec::new(),
    };
    for &id in &after.root {
        walk_page(before, after, id, &mut diff);
@@ -648,6 +659,24 @@ pub fn diff_pages(before: &Document, after: &Document) -> PageDiff {
        &mut diff.variables,
    );
    diff.modified += diff.variables.len();
+    for a in &after.annotations {
+        let status = match before.annotations.iter().find(|b| b.id == a.id) {
+            None => "added",
+            Some(b) if b != a => "modified",
+            Some(_) => continue,
+        };
+        diff.annotations.push(AnnotationDiff { id: a.id, status, label: a.label.clone() });
+    }
+    for b in before.annotations.iter().filter(|b| !after.annotations.iter().any(|a| a.id == b.id)) {
+        diff.annotations.push(AnnotationDiff { id: b.id, status: "removed", label: b.label.clone() });
+    }
+    for a in &diff.annotations {
+        match a.status {
+            "added" => diff.added += 1,
+            "removed" => diff.removed += 1,
+            _ => diff.modified += 1,
+        }
+    }
    diff
 }

@@ -973,6 +1002,24 @@ mod tests {
        (d, f, a, b)
    }

+    #[test]
+    fn diff_pages_annotations_added_removed_modified() {
+        use crate::model::annotation::Annotation;
+        let mut before = Document::default();
+        let (mut keep, mut gone) = (Annotation::new(None, "keep", "rule"), Annotation::new(None, "gone", "rule"));
+        (keep.id, gone.id) = (1, 2);
+        before.annotations = vec![keep, gone];
+        let mut after = before.clone();
+        after.annotations.remove(1);
+        after.annotations[0].body = "edited".into();
+        let mut new = Annotation::new(None, "new", "rule");
+        new.id = 3;
+        after.annotations.push(new);
+        let p = diff_pages(&before, &after);
+        assert_eq!((p.added, p.removed, p.modified), (1, 1, 1));
+        assert!(diff_pages(&before, &before).is_empty());
+    }
+
    #[test]
    fn diff_pages_identical_is_empty() {
        let (d, ..) = page();
@@ -337,6 +337,10 @@ pub fn verify_code(
    let norm_target = normalize_target(target)?;
    let is_egui = norm_target == "egui";

+    // Annotation comments describe rules, not rendered content or layout.
+    let source = code.lines().filter(|line| !line.trim_start().starts_with("//"))
+        .collect::<Vec<_>>().join("\n");
+    let code = source.as_str();
    let visible_ids = visible_subtree(doc, root);

    let mut violations: Vec<Violation> = Vec::new();
@@ -58,8 +58,10 @@ pub struct SessionHost {

 impl SessionHost {
    pub fn new(store: Store) -> SessionHost {
+        let mut ed = Editor::default();
+        ed.headless = true;
        SessionHost {
-            ed: Editor::default(),
+            ed,
            session: Session::new(store),
            gpu: None,
            gpu_tried: false,
@@ -287,6 +289,12 @@ pub fn call(host: &mut dyn Host, name: &str, args: &Value) -> ToolResult {
                "get_screenshot" => screenshot(host, &a),
                "get_jsx" => jsx(host, &a),
                "get_design_spec" => get_design_spec(ed, &a),
+                "annotate" => annotate(ed, &a),
+                "get_annotations" => get_annotations(ed, &a),
+                "get_annotation_template" => get_annotation_template(ed, &a),
+                "set_annotation_template" => set_annotation_template(ed, &a),
+                "update_annotation" => update_annotation(ed, &a),
+                "delete_annotations" => delete_annotations(ed, &a),
                "verify_code" => verify_code(ed, &a),
                "get_computed_styles" => computed_styles(ed, &a),
                "get_fill_image" => fill_image(ed, &a),
@@ -1183,6 +1191,314 @@ fn guide(a: &Args) -> ToolResult {
    Ok(vec![Out::Text(s.into())])
 }

+// ------------------------------------------------------------------------------ annotations
+
+fn annotation_rows(rows: Vec<Value>) -> ToolResult {
+    Ok(vec![Out::Text(serde_json::to_string(&rows).unwrap())])
+}
+
+fn annotation_category(ed: &Editor, key: &str) -> Result<String, String> {
+    ed.design.category_by_key(key).map(|c| c.id).ok_or_else(|| {
+        format!(
+            "unknown annotation type `{key}`; valid keys: {}",
+            ed.design
+                .categories()
+                .iter()
+                .map(|c| c.key().to_string())
+                .collect::<Vec<_>>()
+                .join(", ")
+        )
+    })
+}
+
+fn annotation_node(ed: &Editor, key: &str, page: usize) -> Result<NodeId, String> {
+    if let Ok((p, id)) = resolve(ed, key, page) {
+        return if p == page {
+            Ok(id)
+        } else {
+            Err("all notes must be on the selected page".into())
+        };
+    }
+    let mut matches: Vec<_> = ed
+        .page_doc(page)
+        .nodes
+        .values()
+        .filter(|n| n.name.eq_ignore_ascii_case(key))
+        .map(|n| n.id)
+        .collect();
+    matches.sort_by_key(|id| id.0);
+    match matches.as_slice() {
+        [id] => Ok(*id),
+        [] => Err(format!("node `{key}` not found on page")),
+        _ => Err(format!(
+            "ambiguous node `{key}`; candidates: {}",
+            matches
+                .iter()
+                .take(5)
+                .map(|id| node_key(ed, page, *id))
+                .collect::<Vec<_>>()
+                .join(", ")
+        )),
+    }
+}
+
+fn annotation_text(text: &str) -> (String, String) {
+    let (label, body) = text.split_once('\n').unwrap_or((text, ""));
+    (label.trim_end_matches('\r').into(), body.into())
+}
+
+/// The category id for type `key`, if the page's active template enables it.
+fn enabled_category(ed: &Editor, page: usize, key: &str) -> Result<String, String> {
+    let category = annotation_category(ed, key)?;
+    let template = ed.active_template(page);
+    if template.enabled(key).is_none() {
+        return Err(format!(
+            "type `{key}` is not enabled by template `{}`; allowed: {}",
+            template.name,
+            template.enabled_keys().join(", ")
+        ));
+    }
+    Ok(category)
+}
+
+fn annotate(ed: &mut Editor, a: &Args) -> ToolResult {
+    use crate::model::annotation::{Annotation, Author, auto_position, numbers};
+    let page = page_arg(ed, a)?;
+    let notes = a
+        .arr("notes")?
+        .iter()
+        .map(|v| {
+            let args = Args(v.as_object().ok_or("notes must be objects")?);
+            let node = annotation_node(ed, args.req_str("node")?, page)?;
+            let key = args
+                .get("type")
+                .map(|v| v.as_str().ok_or("type must be a string"))
+                .transpose()?
+                .unwrap_or("rule");
+            let category = enabled_category(ed, page, key)?;
+            let (label, body) = annotation_text(
+                args.get("text")
+                    .and_then(Value::as_str)
+                    .ok_or("missing text string")?,
+            );
+            let mut note = Annotation::new(Some(node), &label, &category);
+            note.body = body;
+            note.author = Author::Agent;
+            Ok(note)
+        })
+        .collect::<Result<Vec<_>, String>>()?;
+    let ids = ed.with_page(page, |ed| {
+        ed.edit("Annotate", |tx| {
+            notes
+                .into_iter()
+                .map(|mut note| {
+                    note.position = auto_position(tx.doc(), note.target.unwrap());
+                    tx.add_annotation(note)
+                })
+                .collect::<Vec<_>>()
+        })
+    });
+    let doc = ed.page_doc(page);
+    let numbers = numbers(doc);
+    let cats = ed.design.categories();
+    annotation_rows(
+        ids.iter()
+            .map(|id| {
+                let note = doc.annotations.iter().find(|n| n.id == *id).unwrap();
+                let key = cats
+                    .iter()
+                    .find(|c| c.id == note.category)
+                    .map(|c| c.key())
+                    .unwrap_or(&note.category);
+                json!([
+                    numbers[id].1,
+                    node_key(ed, page, note.target.unwrap()),
+                    key,
+                    note.label
+                ])
+            })
+            .collect::<Vec<_>>(),
+    )
+}
+
+fn get_annotation_template(ed: &Editor, a: &Args) -> ToolResult {
+    let t = ed.active_template(page_arg(ed, a)?);
+    text(json!({
+        "template": t.name,
+        "types": t.categories.iter().filter(|c| c.enabled)
+            .map(|c| json!([c.key, c.prompt, c.fields])).collect::<Vec<_>>(),
+    }))
+}
+
+fn set_annotation_template(ed: &mut Editor, a: &Args) -> ToolResult {
+    let page = page_arg(ed, a)?;
+    let r = a.req_str("template")?;
+    let t = ed.design.template_by_ref(r).ok_or_else(|| {
+        format!(
+            "unknown template `{r}`; available: {}",
+            ed.design.templates().iter().map(|t| t.name.as_str()).collect::<Vec<_>>().join(", ")
+        )
+    })?;
+    match a.str("scope").unwrap_or("page") {
+        "page" => ed.set_page_template(page, Some(&t.id)),
+        "project" => ed.set_default_template(Some(&t.id)),
+        s => return Err(format!("scope must be page or project, got `{s}`")),
+    }
+    .map_err(|e| e.to_string())?;
+    text(json!({"template": t.name, "scope": a.str("scope").unwrap_or("page")}))
+}
+
+fn get_annotations(ed: &Editor, a: &Args) -> ToolResult {
+    let default_page = page_arg(ed, a)?;
+    let scope = a
+        .str("nodeId")
+        .map(|id| resolve(ed, id, default_page))
+        .transpose()?;
+    let page = scope.map_or(default_page, |s| s.0);
+    let doc = ed.page_doc(page);
+    let subtree = scope.map(|s| doc.subtree(s.1));
+    let numbers = crate::model::annotation::numbers(doc);
+    let cats = ed.design.categories();
+    let mut notes: Vec<_> = doc
+        .annotations
+        .iter()
+        .filter(|note| {
+            subtree
+                .as_ref()
+                .is_none_or(|ids| note.target.is_some_and(|id| ids.contains(&id)))
+        })
+        .collect();
+    notes.sort_by_key(|n| (numbers[&n.id].0.map(|id| id.0), numbers[&n.id].1));
+    annotation_rows(
+        notes
+            .into_iter()
+            .map(|note| {
+                let number = numbers[&note.id].1;
+                let key = cats
+                    .iter()
+                    .find(|c| c.id == note.category)
+                    .map(|c| c.key())
+                    .unwrap_or(&note.category);
+                if a.bool("full").unwrap_or(false) {
+                    let mut value = serde_json::to_value(note).unwrap();
+                    value["number"] = json!(number);
+                    value["type"] = json!(key);
+                    value["nodeId"] = json!(note.target.map(|id| node_key(ed, page, id)));
+                    return value;
+                }
+                let name = note
+                    .target
+                    .and_then(|id| doc.get(id))
+                    .map(|n| n.name.as_str())
+                    .unwrap_or("Detached");
+                let text = if let Some(line) = note.body.lines().next() {
+                    format!("{}\n{line}", note.label)
+                } else {
+                    note.label.clone()
+                };
+                json!([
+                    number,
+                    name,
+                    key,
+                    text.chars().take(120).collect::<String>()
+                ])
+            })
+            .collect::<Vec<_>>(),
+    )
+}
+
+fn annotation_ref(ed: &Editor, value: &Value, page: usize) -> Result<u64, String> {
+    let doc = ed.page_doc(page);
+    let key = value.as_str().map(str::trim);
+    if let Some(id) = value.as_u64().or_else(|| key.and_then(|s| s.parse().ok())) {
+        return doc
+            .annotations
+            .iter()
+            .find(|n| n.id == id)
+            .map(|n| n.id)
+            .ok_or_else(|| format!("annotation {id} not found"));
+    }
+    let (frame, number) = key
+        .and_then(|s| s.rsplit_once('#'))
+        .ok_or("expected annotation id or frame reference such as Sign in #3")?;
+    let number: u32 = number
+        .trim()
+        .parse()
+        .map_err(|_| "invalid annotation number")?;
+    let frame = frame.trim().strip_prefix("frame ").unwrap_or(frame.trim());
+    let numbers = crate::model::annotation::numbers(doc);
+    let matches: Vec<_> = doc
+        .annotations
+        .iter()
+        .filter(|n| {
+            let (root, num) = numbers[&n.id];
+            num == number
+                && root
+                    .and_then(|id| doc.get(id))
+                    .is_some_and(|node| node.name.eq_ignore_ascii_case(frame))
+        })
+        .collect();
+    match matches.as_slice() {
+        [note] => Ok(note.id),
+        [] => Err(format!(
+            "annotation reference `{}` not found",
+            key.unwrap_or_default()
+        )),
+        _ => Err("ambiguous annotation reference; use an annotation id".into()),
+    }
+}
+
+fn update_annotation(ed: &mut Editor, a: &Args) -> ToolResult {
+    let page = page_arg(ed, a)?;
+    let id = annotation_ref(
+        ed,
+        a.get("id")
+            .or_else(|| a.get("ref"))
+            .ok_or("missing id or ref")?,
+        page,
+    )?;
+    let text_value = a
+        .get("text")
+        .map(|v| v.as_str().ok_or("text must be a string"))
+        .transpose()?;
+    let category = a
+        .get("type")
+        .map(|v| enabled_category(ed, page, v.as_str().ok_or("type must be a string")?))
+        .transpose()?;
+    ed.with_page(page, |ed| {
+        ed.update_annotation(id, |note| {
+            if let Some(text) = text_value {
+                (note.label, note.body) = annotation_text(text);
+            }
+            if let Some(category) = category {
+                note.category = category;
+            }
+        })
+    });
+    text(json!({"id": id}))
+}
+
+fn delete_annotations(ed: &mut Editor, a: &Args) -> ToolResult {
+    let page = page_arg(ed, a)?;
+    let values = a
+        .get("ids")
+        .or_else(|| a.get("refs"))
+        .and_then(Value::as_array)
+        .ok_or("missing ids or refs array")?;
+    let ids = values
+        .iter()
+        .map(|v| annotation_ref(ed, v, page))
+        .collect::<Result<Vec<_>, _>>()?;
+    ed.with_page(page, |ed| {
+        ed.edit("Delete annotations", |tx| {
+            for id in &ids {
+                tx.delete_annotation(*id);
+            }
+        })
+    });
+    text(json!({"deleted": ids}))
+}
+
 // ------------------------------------------------------------------------------ jsx

 fn jsx(host: &mut dyn Host, a: &Args) -> ToolResult {
@@ -1194,15 +1510,15 @@ fn jsx(host: &mut dyn Host, a: &Args) -> ToolResult {
    let doc = ed.page_doc(page);
    match a.str("format") {
        None | Some("") | Some("inline") | Some("inline-styles") => {
-            let mut out = String::new();
+            let mut out = super::codegen::annotation_comments(doc, id, &ed.design.categories());
            jsx_node(doc, id, 0, true, assets_dir.as_deref(), &mut out);
            Ok(vec![Out::Text(out)])
        }
        Some(
            f @ ("tailwind" | "jsx" | "react" | "tsx" | "angular" | "ng" | "html" | "css" | "egui"
            | "rust"),
-        ) => Ok(vec![Out::Text(super::codegen::code_for_target(
-            doc, id, f,
+        ) => Ok(vec![Out::Text(super::codegen::code_for_target_with_categories(
+            doc, id, f, &ed.design.categories(),
        )?)]),
        Some(f) => Err(format!(
            "unknown format `{f}` (inline, tailwind, react, angular, html, or egui)"
@@ -1216,11 +1532,11 @@ fn get_design_spec(ed: &mut Editor, a: &Args) -> ToolResult {
    let target = a.str("target").filter(|s| !s.is_empty()).unwrap_or("react");
    match a.str("format").unwrap_or("markdown") {
        "" | "markdown" | "md" => {
-            let md = super::codegen::to_ai_spec_markdown(doc, id, target)?;
+            let md = super::codegen::to_ai_spec_markdown_with_categories(doc, id, target, &ed.design.categories())?;
            Ok(vec![Out::Text(md)])
        }
        "json" => {
-            let spec = super::codegen::to_ai_spec(doc, id, target)?;
+            let spec = super::codegen::to_ai_spec_with_categories(doc, id, target, &ed.design.categories())?;
            text(spec)
        }
        other => Err(format!(
@@ -2821,6 +3137,13 @@ fn clone_subtree(
    (map[&src], pairs)
 }

+/// Copy the annotations on a duplicated subtree, retargeted to the new nodes.
+fn copy_annotations(tx: &mut Tx, from: &[crate::model::annotation::Annotation], pairs: &[(NodeId, NodeId)]) {
+    let map: HashMap<NodeId, NodeId> = pairs.iter().copied().collect();
+    let copies = crate::model::annotation::copies_for(from, &map);
+    tx.add_annotation_copies(copies);
+}
+
 /// A free spot for a new top-level frame: right of the existing artboards, 80 px apart.
 fn free_spot(doc: &Document, w: f64) -> V2 {
    let rects: Vec<Rect> = doc
@@ -3075,6 +3398,9 @@ fn create_shape(ed: &mut Editor, a: &Args) -> ToolResult {
    };
    let sides = a.num("sides").map(|s| s.clamp(3.0, 64.0) as u32);
    let txt = a.str("text").unwrap_or("").to_string();
+    // A top-level shape with no position goes where a new artboard would, not on top of
+    // the first one at the origin.
+    let free = parent.is_none() && a.num("x").is_none() && a.num("y").is_none();
    let (x, y) = (a.num("x").unwrap_or(0.0), a.num("y").unwrap_or(0.0));
    let (w, h) = (a.num("width"), a.num("height"));
    let route = match a.str("route") {
@@ -3092,6 +3418,12 @@ fn create_shape(ed: &mut Editor, a: &Args) -> ToolResult {
    let (id, ignored) = ed.with_page(page, |ed| {
        ed.edit("Add shape", |tx| -> Result<(NodeId, Vec<String>), String> {
            let o = tx.doc().parent_origin(parent);
+            let (x, y) = if free {
+                let p = free_spot(tx.doc(), w.unwrap_or(160.0));
+                (p.x, p.y)
+            } else {
+                (x, y)
+            };
            let rect = Rect::new(x, y, w.unwrap_or(160.0), h.unwrap_or(100.0));
            let kind = match ty.as_str() {
                "rectangle" | "rect" => NodeKind::Rect,
@@ -4608,6 +4940,8 @@ fn duplicate_nodes(ed: &mut Editor, a: &Args) -> ToolResult {
                        V2::ZERO
                    };
                    let r = clone_subtree(tx, id, target, index, offset);
+                    let from = tx.doc().annotations.clone();
+                    copy_annotations(tx, &from, &r.1);
                    relayout(tx, Some(r.0));
                    r
                })
@@ -4625,6 +4959,7 @@ fn duplicate_nodes(ed: &mut Editor, a: &Args) -> ToolResult {
                        -w.min()
                    };
                    let r = clone_subtree_from_doc(tx, &src_doc, id, target, None, offset);
+                    copy_annotations(tx, &src_doc.annotations, &r.1);
                    relayout(tx, target.or(Some(r.0)));
                    r
                })
@@ -87,6 +87,22 @@ pub fn definitions() -> Vec<Value> {
    let node_id = |d: &str| json!({"type": "string", "description": d});
    let ids = |d: &str| json!({"type": "array", "items": {"type": "string"}, "description": d});
    vec![
+        tool("annotate", "Add notes to node ids or exact layer names on a page in one undo step. First text line is label; remaining lines are body. Type is an allowed category key (default rule); put fields as \"Name: value\" lines in text. Placement is automatic. Returns [number, node, type, label] rows.",
+            json!({"pageId": page_id(), "notes": {"type": "array", "items": {
+                "type": "object", "properties": {"node": {"type": "string"},
+                "text": {"type": "string"}, "type": {"type": "string"}}, "required": ["node", "text"]}}}), &["notes"], false),
+        tool("get_annotation_template", "Read the page's annotation template: [type key, guidance, field names] for each allowed type. Call once before annotate.",
+            json!({"pageId": page_id()}), &[], true),
+        tool("set_annotation_template", "Switch the annotation template by id or name, for one page or the whole project. Annotate only accepts the template's types.",
+            json!({"template": {"type": "string"}, "scope": {"type": "string", "enum": ["page", "project"]}, "pageId": page_id()}), &["template"], false),
+        tool("get_annotations", "Read annotations as [number, nodeName, type, text] rows. Text includes label and first body line, limited to 120 characters. Use full for complete objects, nodeId for a subtree, or pageId for another page.",
+            json!({"nodeId": {"type": "string"}, "pageId": page_id(), "full": {"type": "boolean"}}), &[], true),
+        tool("update_annotation", "Update annotation text or category key by id or frame reference such as Sign in #3. First text line is label; remaining lines are body. One undo step.",
+            json!({"id": {"type": ["integer", "string"]}, "ref": {"type": "string"},
+                "text": {"type": "string"}, "type": {"type": "string"}, "pageId": page_id()}), &[], false),
+        tool("delete_annotations", "Delete annotations by ids or frame references such as Sign in #3 in one undo step.",
+            json!({"ids": {"type": "array", "items": {"type": ["integer", "string"]}},
+                "refs": {"type": "array", "items": {"type": "string"}}, "pageId": page_id()}), &[], false),
        // ------------------------------------------------------------ projects and pages
        tool(
            "list_resources",
@@ -900,14 +916,14 @@ fn classify(name: &str, args: &Value) -> Option<bool> {
        "list_resources" | "get_basic_info" | "get_selection" | "get_node_info" | "get_children"
        | "get_tree_summary" | "get_screenshot" | "get_jsx" | "get_design_spec" | "verify_code"
        | "get_computed_styles" | "get_fill_image" | "find_nodes" | "get_font_family_info"
-        | "get_guide" | "get_feedback" | "get_variables" | "get_components" | "search_icons"
+        | "get_annotations" | "get_annotation_template" | "get_guide" | "get_feedback" | "get_variables" | "get_components" | "search_icons"
        | "diff_frames" | "publish_library" | "list_libraries" => false,
        "select_nodes" | "export" | "export_combined_pdf" | "export_design_system" | "open_file"
        | "create_file" | "finish_working_on_nodes" => false,
        "lint_design" => args["fix"] == true,
        "create_page" | "rename_pages" | "delete_pages" | "create_artboard" | "write_html"
        | "create_shape" | "update_styles" | "set_text_content" | "rename_nodes"
-        | "add_feedback" | "resolve_feedback" | "set_variables" | "set_tokens"
+        | "annotate" | "set_annotation_template" | "update_annotation" | "delete_annotations" | "add_feedback" | "resolve_feedback" | "set_variables" | "set_tokens"
        | "create_collection" | "delete_variables" | "bind_variable"
        | "enable_library" | "update_library" | "disable_library"
        | "set_variable_mode" | "import_design_system" | "import_components" | "create_component"
@@ -0,0 +1,315 @@
+//! Annotations: notes that explain a design, attached to a layer (or a point) with a leader line.
+//!
+//! Pure model. The anchor is relative to the target's rect and the note card is positioned
+//! relative to the target's top-left, so moving or resizing the target keeps both attached.
+//! Once the target is deleted the annotation is `detached` and `position` / `point` are world.
+
+use super::document::Document;
+use super::node::{Color, NodeId};
+use crate::geom::V2;
+use serde::{Deserialize, Serialize};
+use std::collections::HashMap;
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Default, Serialize, Deserialize)]
+#[serde(rename_all = "lowercase")]
+pub enum Side {
+    Top,
+    Right,
+    Bottom,
+    Left,
+    #[default]
+    Center,
+}
+
+/// Where the leader line ends: a side of the target's rect and a fraction `t` (0..1) along it.
+#[derive(Debug, Clone, Copy, PartialEq, Default, Serialize, Deserialize)]
+pub struct Anchor {
+    pub side: Side,
+    #[serde(default)]
+    pub t: f64,
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Default, Serialize, Deserialize)]
+#[serde(rename_all = "lowercase")]
+pub enum Author {
+    #[default]
+    User,
+    Agent,
+}
+
+#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
+pub struct Annotation {
+    pub id: u64,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub target: Option<NodeId>,
+    /// World point the line ends at when there is no target.
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub point: Option<V2>,
+    #[serde(default)]
+    pub anchor: Anchor,
+    pub label: String,
+    #[serde(default)]
+    pub body: String,
+    /// Category id (see [`AnnotationCategory`]).
+    #[serde(default)]
+    pub category: String,
+    /// Note card top-left: relative to the target's top-left when `target` is set, else world.
+    pub position: V2,
+    #[serde(default)]
+    pub author: Author,
+    /// Unix milliseconds.
+    #[serde(default)]
+    pub created: u64,
+    /// The target was deleted; the note stays where it was, with a warning badge.
+    #[serde(default, skip_serializing_if = "std::ops::Not::not")]
+    pub detached: bool,
+}
+
+impl Annotation {
+    pub fn new(target: Option<NodeId>, label: &str, category: &str) -> Annotation {
+        Annotation {
+            id: 0,
+            target,
+            point: None,
+            anchor: Anchor::default(),
+            label: label.into(),
+            body: String::new(),
+            category: category.into(),
+            position: V2::ZERO,
+            author: Author::User,
+            created: 0,
+            detached: false,
+        }
+    }
+}
+
+#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
+pub struct AnnotationCategory {
+    pub id: String,
+    /// Short type key used by agents and the UI (`rule`, `a11y`, ...). Empty means the id.
+    #[serde(default)]
+    pub key: String,
+    pub name: String,
+    pub color: Color,
+    pub icon: String,
+}
+
+/// Id (and key) of the category new notes get when none is named.
+pub const DEFAULT_CATEGORY: &str = "rule";
+
+impl AnnotationCategory {
+    /// The type key (the id when none was set).
+    pub fn key(&self) -> &str {
+        if self.key.is_empty() { &self.id } else { &self.key }
+    }
+}
+
+/// Find a category by its type key (case-insensitive).
+pub fn category_by_key<'a>(cats: &'a [AnnotationCategory], key: &str) -> Option<&'a AnnotationCategory> {
+    cats.iter().find(|c| c.key().eq_ignore_ascii_case(key))
+}
+
+/// Size the canvas gives a note card, used to stack automatically placed notes.
+pub const CARD_W: f64 = 220.0;
+pub const CARD_H: f64 = 72.0;
+const CARD_GAP: f64 = 24.0;
+
+/// Where a new note on `target` goes, as a `position` (relative to the target's top-left):
+/// right of the target's top-level frame, level with the target, pushed down past any
+/// existing note card so none overlap.
+pub fn auto_position(doc: &Document, target: NodeId) -> V2 {
+    let Some(t) = doc.world_rect(target) else { return V2::ZERO };
+    let frame = frame_of(doc, target)
+        .and_then(|f| doc.world_rect(f))
+        .unwrap_or(t);
+    let x = frame.right() + CARD_GAP;
+    let mut y = t.y;
+    let cards: Vec<V2> = doc.annotations.iter().map(|a| card_world(doc, a)).collect();
+    while cards.iter().any(|c| {
+        x < c.x + CARD_W && c.x < x + CARD_W && y < c.y + CARD_H && c.y < y + CARD_H
+    }) {
+        y += CARD_H + CARD_GAP / 2.0;
+    }
+    V2 { x: x, y: y } - t.min()
+}
+
+/// The six built-in categories, with stable ids.
+pub fn default_categories() -> Vec<AnnotationCategory> {
+    let c = |id: &str, name: &str, color: Color, icon: &str| AnnotationCategory {
+        id: id.into(),
+        key: id.into(),
+        name: name.into(),
+        color,
+        icon: icon.into(),
+    };
+    vec![
+        c("rule", "Business rule", Color::rgb(0x7c, 0x5c, 0xff), "scale"),
+        c("behaviour", "Behaviour", Color::rgb(0x2f, 0x80, 0xed), "zap"),
+        c("content", "Content", Color::rgb(0x1f, 0xa8, 0x7a), "type"),
+        c("data", "Data", Color::rgb(0xe0, 0x8a, 0x1e), "database"),
+        c("a11y", "Accessibility", Color::rgb(0xd9, 0x4f, 0x8a), "accessibility"),
+        c("dev", "Dev note", Color::rgb(0x6b, 0x72, 0x80), "code"),
+    ]
+}
+
+// ------------------------------------------------------------------------------ templates
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Default, Serialize, Deserialize)]
+#[serde(rename_all = "lowercase")]
+pub enum Display {
+    #[default]
+    Full,
+    Badges,
+}
+
+/// One kind of note a template asks for: guidance for what it should say and optional
+/// structured `Name: value` lines.
+#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
+pub struct TemplateCategory {
+    pub key: String,
+    #[serde(default = "yes")]
+    pub enabled: bool,
+    #[serde(default)]
+    pub prompt: String,
+    #[serde(default, skip_serializing_if = "Vec::is_empty")]
+    pub fields: Vec<String>,
+}
+
+fn yes() -> bool {
+    true
+}
+
+#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
+pub struct AnnotationTemplate {
+    pub id: String,
+    pub name: String,
+    pub categories: Vec<TemplateCategory>,
+    #[serde(default)]
+    pub display: Display,
+}
+
+impl AnnotationTemplate {
+    /// The enabled category with this type key (case-insensitive).
+    pub fn enabled(&self, key: &str) -> Option<&TemplateCategory> {
+        self.categories.iter().find(|c| c.enabled && c.key.eq_ignore_ascii_case(key))
+    }
+
+    /// Keys of the enabled categories, in order.
+    pub fn enabled_keys(&self) -> Vec<&str> {
+        self.categories.iter().filter(|c| c.enabled).map(|c| c.key.as_str()).collect()
+    }
+}
+
+/// Id of the template used when neither the project nor the page picks one.
+pub const DEFAULT_TEMPLATE: &str = "product-spec";
+
+fn default_prompt(key: &str) -> &'static str {
+    match key {
+        "rule" => "The business rule or constraint this part enforces.",
+        "behaviour" => "What happens on interaction: states, transitions, edge cases.",
+        "content" => "The copy here: meaning, tone and limits.",
+        "data" => "Where the data comes from, its format and what if it is missing.",
+        "dev" => "Implementation note for developers.",
+        "a11y" => "Accessibility requirement: role, label, focus order, contrast.",
+        _ => "",
+    }
+}
+
+/// The five built-in templates (editable copies are stored in `design.json`).
+pub fn builtin_templates() -> Vec<AnnotationTemplate> {
+    let t = |id: &str, name: &str, cats: &[(&str, &[&str])]| AnnotationTemplate {
+        id: id.into(),
+        name: name.into(),
+        categories: cats
+            .iter()
+            .map(|(key, fields)| TemplateCategory {
+                key: (*key).into(),
+                enabled: true,
+                prompt: default_prompt(key).into(),
+                fields: fields.iter().map(|f| (*f).into()).collect(),
+            })
+            .collect(),
+        display: Display::Full,
+    };
+    vec![
+        t("product-spec", "Product spec", &[("rule", &[]), ("behaviour", &[]), ("content", &[]), ("data", &[])]),
+        t("dev-handoff", "Dev handoff", &[("behaviour", &[]), ("data", &[]), ("dev", &[]), ("a11y", &[])]),
+        t("accessibility-review", "Accessibility review", &[("a11y", &["Issue", "WCAG", "Fix"])]),
+        t("content-review", "Content review", &[("content", &["Tone", "Max length"])]),
+        t("minimal", "Minimal", &[("rule", &[])]),
+    ]
+}
+
+/// The leader line's end in world space.
+pub fn anchor_world(doc: &Document, a: &Annotation) -> V2 {
+    let Some(r) = a.target.and_then(|t| doc.world_rect(t)) else {
+        return a.point.unwrap_or(a.position);
+    };
+    let t = a.anchor.t.clamp(0.0, 1.0);
+    match a.anchor.side {
+        Side::Top => V2 { x: r.x + t * r.w, y: r.y },
+        Side::Bottom => V2 { x: r.x + t * r.w, y: r.y + r.h },
+        Side::Left => V2 { x: r.x, y: r.y + t * r.h },
+        Side::Right => V2 { x: r.x + r.w, y: r.y + t * r.h },
+        Side::Center => r.center(),
+    }
+}
+
+/// The note card's top-left in world space.
+pub fn card_world(doc: &Document, a: &Annotation) -> V2 {
+    match a.target.and_then(|t| doc.world_rect(t)) {
+        Some(r) => r.min() + a.position,
+        None => a.position,
+    }
+}
+
+/// The top-level frame a node lives in (the node itself when it is top level).
+pub fn frame_of(doc: &Document, id: NodeId) -> Option<NodeId> {
+    doc.nodes.get(&id)?;
+    Some(doc.ancestors(id).last().copied().unwrap_or(id))
+}
+
+/// Number of every annotation, per top-level frame in reading order (target's world y, then x).
+/// Annotations without a frame come last, numbered globally from 1, with frame `None`.
+pub fn numbers(doc: &Document) -> HashMap<u64, (Option<NodeId>, u32)> {
+    let mut keyed: Vec<(Option<NodeId>, V2, u64)> = doc
+        .annotations
+        .iter()
+        .map(|a| {
+            let frame = a.target.and_then(|t| frame_of(doc, t));
+            let at = a
+                .target
+                .and_then(|t| doc.world_rect(t))
+                .map_or_else(|| anchor_world(doc, a), |r| r.min());
+            (frame, at, a.id)
+        })
+        .collect();
+    keyed.sort_by(|a, b| {
+        (a.0.is_none(), a.1.y, a.1.x, a.2)
+            .partial_cmp(&(b.0.is_none(), b.1.y, b.1.x, b.2))
+            .unwrap_or(std::cmp::Ordering::Equal)
+    });
+    let mut count: HashMap<Option<NodeId>, u32> = HashMap::new();
+    let mut out = HashMap::new();
+    for (frame, _, id) in keyed {
+        let n = count.entry(frame).or_insert(0);
+        *n += 1;
+        out.insert(id, (frame, *n));
+    }
+    out
+}
+
+/// Copies of the annotations whose target is a key of `map`, retargeted to its value. Ids are
+/// unset (`Tx::add_annotation_copies` allocates them).
+pub fn copies_for(
+    annotations: &[Annotation],
+    map: &HashMap<NodeId, NodeId>,
+) -> Vec<Annotation> {
+    annotations
+        .iter()
+        .filter_map(|a| {
+            let t = map.get(&a.target?)?;
+            Some(Annotation { target: Some(*t), ..a.clone() })
+        })
+        .collect()
+}
@@ -1,5 +1,6 @@
 //! The document arena: nodes keyed by id plus ordered child lists.

+use super::annotation::Annotation;
 use super::node::{Color, Node, NodeId};
 use crate::geom::{Rect, V2};
 use serde::{Deserialize, Serialize};
@@ -25,6 +26,9 @@ pub struct Document {
    /// substituted for `var(--name)` when styles are written.
    #[serde(default)]
    pub tokens: BTreeMap<String, String>,
+    /// Notes that explain the design. Absent from page files when empty.
+    #[serde(default)]
+    pub annotations: Vec<Annotation>,
 }

 impl Default for Document {
@@ -38,6 +42,7 @@ impl Default for Document {
            modes: BTreeMap::new(),
            mode: None,
            tokens: BTreeMap::new(),
+            annotations: Vec::new(),
        }
    }
 }
@@ -1,3 +1,4 @@
+pub mod annotation;
 pub mod document;
 pub mod node;
 pub mod paint;
@@ -6,7 +6,8 @@
 //! unit-testable on its own.

 use crate::geom::Camera;
-use crate::variables::PageModes;
+use crate::variables::{PAGE_TEMPLATE_KEY, PageModes};
+use crate::model::annotation::Annotation;
 use crate::model::{Color, Document, Node, NodeId};
 use serde::{Deserialize, Serialize};
 use serde_json::{Value, json};
@@ -149,6 +150,11 @@ struct PageFile {
    /// Active mode id per collection id.
    #[serde(default, rename = "collectionModes", skip_serializing_if = "BTreeMap::is_empty")]
    modes_by_collection: BTreeMap<String, String>,
+    #[serde(default, skip_serializing_if = "Vec::is_empty")]
+    annotations: Vec<Annotation>,
+    /// This page's annotation template (overrides the project default).
+    #[serde(default, rename = "annotationTemplate", skip_serializing_if = "Option::is_none")]
+    annotation_template: Option<String>,
 }

 /// Page migrations, indexed by source version: `PAGE_STEPS[0]` turns v1 into v2.
@@ -206,7 +212,9 @@ pub fn page_to_json_modes(p: &PageData, modes: &PageModes) -> String {
        modes: p.doc.modes.clone(),
        mode: p.doc.mode.clone(),
        tokens: p.doc.tokens.clone(),
-        modes_by_collection: modes.clone(),
+        modes_by_collection: modes.iter().filter(|(k, _)| *k != PAGE_TEMPLATE_KEY).map(|(k, v)| (k.clone(), v.clone())).collect(),
+        annotations: p.doc.annotations.clone(),
+        annotation_template: modes.get(PAGE_TEMPLATE_KEY).cloned(),
    };
    serde_json::to_string_pretty(&f).expect("page serializes")
 }
@@ -220,7 +228,10 @@ pub fn page_from_json(s: &str) -> Result<PageData, FormatError> {
 pub fn page_from_json_modes(s: &str) -> Result<(PageData, PageModes), FormatError> {
    let v: Value = serde_json::from_str(s).map_err(FormatError::Json)?;
    let v = migrate(v, PAGE_FORMAT, PAGE_VERSION, PAGE_ALIASES, PAGE_STEPS)?;
-    let f: PageFile = serde_json::from_value(v).map_err(FormatError::Json)?;
+    let mut f: PageFile = serde_json::from_value(v).map_err(FormatError::Json)?;
+    if let Some(t) = f.annotation_template.take() {
+        f.modes_by_collection.insert(PAGE_TEMPLATE_KEY.into(), t);
+    }
    let max_id = f.nodes.iter().map(|n| n.id.0).max().unwrap_or(0);
    let nodes: HashMap<NodeId, Node> = f.nodes.into_iter().map(|n| (n.id, n)).collect();
    let doc = Document {
@@ -232,6 +243,7 @@ pub fn page_from_json_modes(s: &str) -> Result<(PageData, PageModes), FormatErro
        modes: f.modes,
        mode: f.mode,
        tokens: f.tokens,
+        annotations: f.annotations,
    };
    doc.validate().map_err(FormatError::Invalid)?;
    Ok((
@@ -322,6 +334,41 @@ mod tests {
        assert_eq!(page_to_json(&back), s);
    }

+    fn page_with(doc: Document) -> PageData {
+        PageData { id: "abc".into(), name: "Plan".into(), doc, camera: None }
+    }
+
+    #[test]
+    fn annotations_roundtrip_and_old_pages_stay_byte_identical() {
+        use crate::model::annotation::{Annotation, Anchor, Side};
+        let ed = demo::showcase();
+        let plain = page_to_json(&page_with(Document { name: "Plan".into(), ..ed.doc.clone() }));
+        assert!(!plain.contains("annotations"), "empty list is not written");
+        // An old file (no field) loads and saves to the same bytes.
+        let old = page_from_json(&plain).unwrap();
+        assert!(old.doc.annotations.is_empty());
+        assert_eq!(page_to_json(&old), plain);
+
+        let mut doc = Document { name: "Plan".into(), ..ed.doc.clone() };
+        let mut a = Annotation::new(doc.root.first().copied(), "Rule", "business-rule");
+        a.id = 77;
+        a.body = "**bold**".into();
+        a.anchor = Anchor { side: Side::Top, t: 0.5 };
+        a.position = crate::geom::v2(12.0, -30.0);
+        a.created = 1234;
+        doc.annotations.push(a);
+        let mut d = Annotation::new(None, "Gone", "data");
+        d.id = 78;
+        d.point = Some(crate::geom::v2(1.0, 2.0));
+        d.detached = true;
+        doc.annotations.push(d);
+        let p = page_with(doc);
+        let s = page_to_json(&p);
+        let back = page_from_json(&s).unwrap();
+        assert_eq!(back, p);
+        assert_eq!(page_to_json(&back), s);
+    }
+
    #[test]
    fn legacy_v1_file_migrates_to_page() {
        let ed = demo::showcase();
@@ -124,6 +124,28 @@ pub fn revert(project: &Path, ed: &mut Editor, run: &mut Run) -> Result<(), Stri
    Ok(())
 }

+/// The run `id` and every later run of the project (all chats, all pages) that can still be
+/// reverted, newest first. `runs` is in `list` order (newest first).
+pub fn runs_from(runs: &[Run], id: &str) -> Vec<Run> {
+    let Some(from) = runs.iter().find(|r| r.id == id) else { return Vec::new() };
+    let key = (from.started, from.number);
+    runs.iter()
+        .filter(|r| (r.started, r.number) >= key && ![RunState::Reverted, RunState::Running].contains(&r.state))
+        .cloned()
+        .collect()
+}
+
+/// "Restore to here": reverts `runs` (newest first, see [`runs_from`]) one by one, so each page
+/// ends as it was before the oldest of them. Stops at the first failure. Returns how many were reverted.
+pub fn revert_all(project: &Path, ed: &mut Editor, runs: Vec<Run>) -> Result<usize, String> {
+    let mut done = 0;
+    for mut run in runs {
+        revert(project, ed, &mut run).map_err(|e| format!("run {}: {e}", run.number))?;
+        done += 1;
+    }
+    Ok(done)
+}
+
 /// Undoes one row of a run's diff on `page_id`, as one undo step on that page. A modified node gets
 /// its snapshot properties back (children stay as they are now), a removed subtree returns under its
 /// old parent at its old index (page root when the parent is gone), an added subtree is deleted.
@@ -359,6 +381,12 @@ impl Tracker {
        r
    }

+    /// Closes the open run now (a chat turn is over), the way `finish_working_on_nodes` does,
+    /// instead of waiting `RUN_IDLE_SECS`.
+    pub fn finish(&mut self, now: u64, ed: &Editor) {
+        self.end(now, Some(ed), None);
+    }
+
    /// Per frame: closes the run after `RUN_IDLE_SECS` idle or when the user switched project.
    pub fn tick(&mut self, now: u64, dir: Option<&Path>, ed: &Editor) {
        self.sync_project(now, dir);
@@ -700,6 +728,43 @@ mod tests {
        }
    }

+    #[test]
+    fn restore_to_here_reverts_this_run_and_every_later_one_across_pages() {
+        use crate::geom::Rect;
+        use crate::model::{Node, NodeKind};
+
+        let dir = temp();
+        let mut ed = Editor::default();
+        ed.add_page_in_background(Some("Second"));
+        let add = |ed: &mut Editor, page: usize, name: &str| {
+            ed.switch_page(page);
+            let mut n = Node::new(NodeId(0), NodeKind::Rect, Rect::new(0.0, 0.0, 10.0, 10.0));
+            n.name = name.into();
+            ed.add_node(n, None);
+        };
+        // Run 1 touches page 0, run 2 page 1, run 3 page 0 again; each snapshots before it edits.
+        let mut runs = Vec::new();
+        let originals: Vec<_> = (0..2).map(|i| ed.page_data(i).doc.nodes.len()).collect();
+        for (n, page) in [(1, 0), (2, 1), (3, 0)] {
+            let mut r = run(n);
+            r.state = RunState::Review;
+            r.pages.push(snapshot_page(&dir, &ed, page));
+            save(&dir, &r).unwrap();
+            add(&mut ed, page, &format!("run{n}"));
+            runs.push(r);
+        }
+        runs.reverse();
+        let picked = runs_from(&runs, "r2");
+        assert_eq!(picked.iter().map(|r| r.number).collect::<Vec<_>>(), [3, 2], "this run and the later ones, newest first");
+        assert_eq!(revert_all(&dir, &mut ed, picked).unwrap(), 2);
+        assert_eq!(ed.page_data(1).doc.nodes.len(), originals[1], "page 1 is back before run 2");
+        assert_eq!(ed.page_data(0).doc.nodes.len(), originals[0] + 1, "run 1 stays");
+        let states: Vec<_> = list(&dir).iter().map(|r| (r.number, r.state)).collect();
+        assert_eq!(states, [(3, RunState::Reverted), (2, RunState::Reverted), (1, RunState::Review)]);
+        assert!(runs_from(&list(&dir), "r2").is_empty(), "already reverted runs are not offered again");
+        std::fs::remove_dir_all(dir).ok();
+    }
+
    #[test]
    fn revert_one_change_leaves_the_others_and_is_one_undo() {
        use crate::geom::Rect;
@@ -1027,6 +1092,28 @@ mod tests {
        t.call(h, "write_html", &args, now).unwrap();
    }

+    #[test]
+    fn annotation_only_run_is_kept_counted_reverted_and_undone() {
+        let (mut h, mut t) = (host(), Tracker::default());
+        write(&mut t, &mut h, T0);
+        t.tick(T0 + GAP + 1, Some(&dir_of(&h)), &h.ed);
+        t.take_finished().unwrap();
+        let node = h.ed.doc.root[0].0.to_string();
+        let notes = json!({"notes": [{"node": node, "text": "Rule one"}, {"node": node, "text": "Rule two"}]});
+        t.call(&mut h, "annotate", &notes, T0 + GAP + 2).unwrap();
+        assert_eq!(h.ed.doc.annotations.len(), 2);
+        assert_eq!(t.counts(&h.ed), Some((2, 0, 0, false)));
+        t.tick(T0 + 2 * GAP + 3, Some(&dir_of(&h)), &h.ed);
+        let mut run = t.take_finished().expect("annotation-only run kept");
+        assert_eq!((run.added, run.changed, run.removed), (2, 0, 0));
+        assert_eq!(run.state, RunState::Review);
+        let with_notes = h.ed.doc.annotations.clone();
+        revert(&dir_of(&h), &mut h.ed, &mut run).unwrap();
+        assert!(h.ed.doc.annotations.is_empty());
+        h.ed.undo();
+        assert_eq!(h.ed.doc.annotations, with_notes);
+    }
+
    #[test]
    fn target_pages_resolves_nested_sources_and_destinations() {
        let mut ed = Editor::default();
@@ -652,6 +652,50 @@ pub enum Icon {
    Laser,
    Library,
    Sketch,
+    Note,
+    Scale,
+    Database,
+    Accessibility,
+    Code,
+    Zap,
+}
+
+/// The app's painted icon for a Lucide name, when it has one.
+#[must_use]
+pub fn icon_by_name(name: &str) -> Option<Icon> {
+    Some(match name {
+        "chevron-right" => Icon::ChevronRight,
+        "chevron-down" => Icon::ChevronDown,
+        "chevron-up" => Icon::ChevronUp,
+        "plus" => Icon::Plus,
+        "minus" => Icon::Minus,
+        "trash-2" => Icon::Trash,
+        "lock" => Icon::Lock,
+        "unlock" => Icon::LockOpen,
+        "eye" => Icon::Eye,
+        "eye-off" => Icon::EyeSlash,
+        "panel-left" => Icon::Sidebar,
+        "hand" => Icon::Hand,
+        "mouse-pointer-2" => Icon::Pointer,
+        "pencil" => Icon::Pencil,
+        "pen" => Icon::Pen,
+        "eraser" => Icon::Eraser,
+        "type" => Icon::Text,
+        "square" => Icon::Rect,
+        "circle" => Icon::Ellipse,
+        "image" => Icon::Image,
+        "star" => Icon::Star,
+        "scale" => Icon::Scale,
+        "zap" => Icon::Zap,
+        "database" => Icon::Database,
+        "accessibility" => Icon::Accessibility,
+        "code" => Icon::Code,
+        "grid-3x3" => Icon::Grid,
+        "ellipsis" => Icon::More,
+        "download" => Icon::Export,
+        "circle-question-mark" => Icon::Question,
+        _ => return None,
+    })
 }

 pub fn paint_icon(painter: &egui::Painter, rect: Rect, icon: Icon, color: Color32) {
@@ -999,6 +1043,58 @@ pub fn paint_icon(painter: &egui::Painter, rect: Rect, icon: Icon, color: Color3
            ]);
            line(&[pt(13.5, 9.5), pt(9.5, 9.5), pt(9.5, 13.5)]);
        }
+        Icon::Note => {
+            closed(&[
+                pt(2.5, 2.5),
+                pt(13.5, 2.5),
+                pt(13.5, 10.5),
+                pt(8.0, 10.5),
+                pt(5.0, 13.5),
+                pt(5.0, 10.5),
+                pt(2.5, 10.5),
+            ]);
+            line(&[pt(5.0, 5.5), pt(11.0, 5.5)]);
+            line(&[pt(5.0, 7.8), pt(9.0, 7.8)]);
+        }
+        Icon::Scale => {
+            line(&[pt(8.0, 2.0), pt(8.0, 14.0)]);
+            line(&[pt(4.7, 14.0), pt(11.3, 14.0)]);
+            line(&[pt(2.0, 4.7), pt(3.3, 4.7), pt(8.0, 3.3), pt(12.7, 4.7), pt(14.0, 4.7)]);
+            for x in [3.3, 12.7] {
+                line(&[pt(x - 2.0, 10.7), pt(x, 5.3), pt(x + 2.0, 10.7)]);
+                painter.add(egui::Shape::line(arc(pt(x, 10.7), 2.0 * u, 0.0, std::f32::consts::PI, 10), st));
+            }
+        }
+        Icon::Database => {
+            let ell = |cy: f32, a0: f32, a1: f32| -> Vec<Pos2> {
+                (0..=16)
+                    .map(|i| {
+                        let a = a0 + (a1 - a0) * i as f32 / 16.0;
+                        pt(8.0 + 5.3 * a.cos(), cy + 2.0 * a.sin())
+                    })
+                    .collect()
+            };
+            closed(&ell(4.0, 0.0, std::f32::consts::TAU - 0.4));
+            line(&ell(8.0, 0.0, std::f32::consts::PI));
+            line(&ell(12.0, 0.0, std::f32::consts::PI));
+            line(&[pt(2.7, 4.0), pt(2.7, 12.0)]);
+            line(&[pt(13.3, 4.0), pt(13.3, 12.0)]);
+        }
+        Icon::Accessibility => {
+            painter.circle_stroke(c, 6.5 * u, st);
+            painter.circle_filled(pt(8.0, 4.9), 0.9 * u, color);
+            line(&[pt(4.8, 6.9), pt(11.2, 6.9)]);
+            line(&[pt(8.0, 6.9), pt(8.0, 9.6)]);
+            line(&[pt(6.4, 12.0), pt(8.0, 9.6), pt(9.6, 12.0)]);
+        }
+        Icon::Code => {
+            line(&[pt(5.3, 4.7), pt(2.0, 8.0), pt(5.3, 11.3)]);
+            line(&[pt(10.7, 4.7), pt(14.0, 8.0), pt(10.7, 11.3)]);
+            line(&[pt(9.3, 3.0), pt(6.7, 13.0)]);
+        }
+        Icon::Zap => {
+            closed(&[pt(9.2, 1.5), pt(3.0, 8.8), pt(7.6, 8.8), pt(6.8, 14.5), pt(13.0, 7.2), pt(8.4, 7.2)]);
+        }
        Icon::Diamond => {
            closed(&[pt(8.0, 1.8), pt(14.2, 8.0), pt(8.0, 14.2), pt(1.8, 8.0)]);
        }
@@ -0,0 +1,487 @@
+//! Annotations on the canvas: note cards in screen space, elbow leader lines to their targets,
+//! drag to move, click to select, and the view states (global mode, per-category, per-note).
+//! Drawn as an egui overlay only, so exports and Present mode never include it.
+
+use crate::editor::Editor;
+use crate::editor::shortcuts;
+use crate::geom::V2;
+use crate::model::annotation::{
+    Annotation, AnnotationCategory, CARD_H, CARD_W, Display, Side, anchor_world, card_world, numbers,
+};
+use crate::theme::{self, Icon};
+use egui::{Align2, Color32, Galley, Pos2, Rect, Sense, Stroke, vec2};
+use std::collections::{HashMap, HashSet};
+use std::hash::{Hash, Hasher};
+use std::sync::Arc;
+
+/// How much of each note the canvas shows.
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum Mode {
+    Full,
+    Badges,
+    Hidden,
+}
+
+impl Mode {
+    pub fn next(self) -> Mode {
+        match self {
+            Mode::Full => Mode::Badges,
+            Mode::Badges => Mode::Hidden,
+            Mode::Hidden => Mode::Full,
+        }
+    }
+}
+
+impl From<Display> for Mode {
+    fn from(d: Display) -> Mode {
+        match d {
+            Display::Full => Mode::Full,
+            Display::Badges => Mode::Badges,
+        }
+    }
+}
+
+type GalleyKey = (u64, u64, u32, bool);
+
+/// View state (never saved): global mode, hidden categories, collapsed notes, the drag in
+/// progress and the text layout cache.
+#[derive(Default)]
+pub struct AnnotationsView {
+    /// `None` follows the page template's display.
+    pub mode: Option<Mode>,
+    pub hidden_categories: HashSet<String>,
+    pub collapsed: HashSet<u64>,
+    drag: Option<(u64, V2)>,
+    galleys: HashMap<GalleyKey, Arc<Galley>>,
+    nums: Option<(u64, Arc<Numbers>)>,
+}
+
+pub type Numbers = HashMap<u64, (Option<crate::model::NodeId>, u32)>;
+
+impl AnnotationsView {
+    /// Note numbers of the active page, recomputed only when the document changed.
+    pub fn numbers(&mut self, ed: &Editor) -> Arc<Numbers> {
+        if let Some((stamp, n)) = &self.nums
+            && *stamp == ed.doc_stamp
+        {
+            return n.clone();
+        }
+        let n = Arc::new(numbers(&ed.doc));
+        self.nums = Some((ed.doc_stamp, n.clone()));
+        n
+    }
+
+    pub fn effective(&self, template_display: Display) -> Mode {
+        self.mode.unwrap_or_else(|| template_display.into())
+    }
+
+    /// Full -> Badges -> Hidden -> Full.
+    pub fn cycle(&mut self, template_display: Display) {
+        self.mode = Some(self.effective(template_display).next());
+    }
+}
+
+const SCALE_MIN: f64 = 0.6;
+const SCALE_MAX: f64 = 1.5;
+const SCALE_STEP: f64 = 0.1;
+const GALLEY_CACHE_MAX: usize = 512;
+const PAD: f32 = 12.0;
+const BADGE_R: f32 = 9.0;
+const BADGE_ONLY: f32 = 22.0;
+const LABEL_PT: f32 = 13.0;
+const BODY_PT: f32 = 11.0;
+const BODY_ROWS: usize = 2;
+const ICON_PX: f32 = 14.0;
+const RADIUS: f32 = 10.0;
+const LINE_W: f32 = 1.5;
+const DOT_R: f32 = 3.5;
+const LINE_HIT: f32 = 5.0;
+const OUTLINE_W: f32 = 2.0;
+const OUTLINE_R: f32 = 4.0;
+const PILL_LIFT: f32 = 72.0;
+
+/// Card scale for a zoom: follows the zoom but stays readable, in coarse steps so the text
+/// layout cache is not thrashed while zooming.
+fn scale_bucket(zoom: f64) -> u32 {
+    (zoom.clamp(SCALE_MIN, SCALE_MAX) / SCALE_STEP).round() as u32
+}
+
+fn bucket_scale(b: u32) -> f32 {
+    (f64::from(b) * SCALE_STEP) as f32
+}
+
+/// Orthogonal leader line from a note card (or badge) rect to `anchor`: straight down/up when the
+/// anchor is above or below the card, else out of the facing side with one elbow.
+pub fn leader_route(card: Rect, anchor: Pos2) -> Vec<Pos2> {
+    if anchor.x >= card.left() && anchor.x <= card.right() {
+        let y = if anchor.y < card.top() { card.top() } else { card.bottom() };
+        return vec![Pos2::new(anchor.x, y), anchor];
+    }
+    let sx = if anchor.x > card.right() { card.right() } else { card.left() };
+    let s = Pos2::new(sx, card.center().y);
+    if (s.y - anchor.y).abs() < 0.5 {
+        return vec![s, anchor];
+    }
+    let mx = (s.x + anchor.x) / 2.0;
+    vec![s, Pos2::new(mx, s.y), Pos2::new(mx, anchor.y), anchor]
+}
+
+/// Point on `target`'s edge facing `from`: the side `from` lies beside, level with it (clamped).
+fn edge_toward(target: Rect, from: Pos2) -> Pos2 {
+    if from.x > target.right() {
+        Pos2::new(target.right(), from.y.clamp(target.top(), target.bottom()))
+    } else if from.x < target.left() {
+        Pos2::new(target.left(), from.y.clamp(target.top(), target.bottom()))
+    } else {
+        let y = if from.y < target.top() { target.top() } else { target.bottom() };
+        Pos2::new(from.x, y)
+    }
+}
+
+fn near_line(pts: &[Pos2], p: Pos2) -> bool {
+    pts.windows(2).any(|w| {
+        let (a, b) = (w[0], w[1]);
+        let ab = b - a;
+        let len2 = ab.length_sq();
+        let t = if len2 > 0.0 { ((p - a).dot(ab) / len2).clamp(0.0, 1.0) } else { 0.0 };
+        (a + ab * t).distance(p) <= LINE_HIT
+    })
+}
+
+fn c32(c: crate::model::Color) -> Color32 {
+    super::c32(c)
+}
+
+struct Item<'a> {
+    a: &'a Annotation,
+    n: u32,
+    color: Color32,
+    icon: Icon,
+    rect: Rect,
+    badge_only: bool,
+    route: Vec<Pos2>,
+    target: Option<Rect>,
+}
+
+fn text_hash(a: &Annotation) -> u64 {
+    let mut h = std::collections::hash_map::DefaultHasher::new();
+    a.label.hash(&mut h);
+    a.body.hash(&mut h);
+    h.finish()
+}
+
+fn galley(
+    ui: &egui::Ui,
+    cache: &mut HashMap<GalleyKey, Arc<Galley>>,
+    key: GalleyKey,
+    text: &str,
+    font: egui::FontId,
+    wrap: f32,
+    rows: usize,
+) -> Arc<Galley> {
+    if cache.len() > GALLEY_CACHE_MAX {
+        cache.clear();
+    }
+    cache
+        .entry(key)
+        .or_insert_with(|| {
+            let mut job = egui::text::LayoutJob::simple(text.to_owned(), font, Color32::WHITE, wrap);
+            job.wrap.max_rows = rows;
+            job.wrap.break_anywhere = false;
+            job.wrap.overflow_character = Some('…');
+            ui.fonts_mut(|f| f.layout_job(job))
+        })
+        .clone()
+}
+
+/// Draw the overlay and the bottom pill; apply a finished drag as one undo step.
+pub fn draw(
+    ctx: &egui::Context,
+    ed: &mut Editor,
+    view: &mut AnnotationsView,
+    selected: &mut Option<u64>,
+    canvas: egui::Rect,
+) {
+    if ed.doc.annotations.is_empty() {
+        return;
+    }
+    let mode = view.effective(ed.active_template(ed.active_page).display);
+    let mut commit: Option<(u64, V2)> = None;
+    if mode != Mode::Hidden {
+        commit = cards(ctx, ed, view, selected, canvas, mode);
+    }
+    pill(ctx, ed, view, canvas, mode);
+    if let Some((id, off)) = commit {
+        ed.update_annotation(id, |a| a.position = a.position + off);
+    }
+}
+
+fn cards(
+    ctx: &egui::Context,
+    ed: &Editor,
+    view: &mut AnnotationsView,
+    selected: &mut Option<u64>,
+    canvas: Rect,
+    mode: Mode,
+) -> Option<(u64, V2)> {
+    let cam = ed.camera;
+    let bucket = scale_bucket(cam.zoom);
+    let s = bucket_scale(bucket);
+    let cats: Vec<AnnotationCategory> = ed.design.categories();
+    let nums = view.numbers(ed);
+    let to_screen = |w: V2| {
+        let v = cam.world_to_screen(w);
+        canvas.min + vec2(v.x as f32, v.y as f32)
+    };
+    let drag = view.drag;
+    let mut items: Vec<Item> = Vec::new();
+    for a in &ed.doc.annotations {
+        if view.hidden_categories.contains(&a.category) {
+            continue;
+        }
+        let cat = cats.iter().find(|c| c.id == a.category).or(cats.first());
+        let (color, icon) = cat.map_or((Color32::GRAY, Icon::Sticky), |c| {
+            (c32(c.color), theme::icon_by_name(&c.icon).unwrap_or(Icon::Sticky))
+        });
+        let mut at = card_world(&ed.doc, a);
+        if let Some((id, off)) = drag.filter(|(id, _)| *id == a.id) {
+            let _ = id;
+            at = at + off;
+        }
+        let badge_only = mode == Mode::Badges || view.collapsed.contains(&a.id);
+        let size = if badge_only {
+            vec2(BADGE_ONLY * s, BADGE_ONLY * s)
+        } else {
+            vec2(CARD_W as f32 * s, CARD_H as f32 * s)
+        };
+        let rect = Rect::from_min_size(to_screen(at), size);
+        let lineless = a.detached || (a.target.is_none() && a.point.is_none());
+        let target = a.target.and_then(|t| ed.doc.world_rect(t)).map(|r| {
+            let r = cam.world_rect_to_screen(&r);
+            Rect::from_min_size(
+                canvas.min + vec2(r.x as f32, r.y as f32),
+                vec2(r.w as f32, r.h as f32),
+            )
+        });
+        let mut anchor = to_screen(anchor_world(&ed.doc, a));
+        if a.anchor.side == Side::Center
+            && let Some(t) = target
+        {
+            anchor = edge_toward(t, rect.center());
+        }
+        let route = if lineless { Vec::new() } else { leader_route(rect, anchor) };
+        let bounds = route.iter().fold(rect, |r, p| r.union(Rect::from_min_max(*p, *p)));
+        if !canvas.intersects(bounds) {
+            continue;
+        }
+        items.push(Item {
+            a,
+            n: nums.get(&a.id).map_or(0, |n| n.1),
+            color,
+            icon,
+            rect,
+            badge_only,
+            route,
+            target,
+        });
+    }
+
+    let mut commit = None;
+    let pointer = ctx.pointer_hover_pos();
+    egui::Area::new("annotations-overlay".into())
+        .order(egui::Order::Middle)
+        .fade_in(false)
+        .fixed_pos(canvas.min)
+        .show(ctx, |ui| {
+            ui.set_clip_rect(canvas);
+            let p = theme::pal(ui);
+            let painter = ui.painter().clone();
+            for it in &items {
+                if it.route.len() < 2 {
+                    continue;
+                }
+                painter.add(egui::Shape::line(it.route.clone(), Stroke::new(LINE_W, it.color)));
+                painter.circle_filled(*it.route.last().unwrap(), DOT_R, it.color);
+            }
+            for it in &items {
+                let a = it.a;
+                let resp = ui.interact(it.rect, egui::Id::new(("annotation-card", a.id)), Sense::click_and_drag());
+                let badge_rect = Rect::from_center_size(
+                    if it.badge_only {
+                        it.rect.center()
+                    } else {
+                        it.rect.min + vec2(PAD + BADGE_R, PAD + BADGE_R) * s
+                    },
+                    vec2(BADGE_R * 2.0, BADGE_R * 2.0) * s,
+                );
+                let badge = ui.interact(badge_rect, egui::Id::new(("annotation-badge", a.id)), Sense::click());
+                let on_line = pointer.is_some_and(|ptr| near_line(&it.route, ptr));
+                let is_sel = *selected == Some(a.id);
+                if (resp.hovered() || on_line || is_sel)
+                    && let Some(t) = it.target
+                {
+                    painter.rect_stroke(t, OUTLINE_R, Stroke::new(OUTLINE_W, it.color), egui::StrokeKind::Outside);
+                }
+                if resp.hovered() || on_line {
+                    ctx.set_cursor_icon(if resp.dragged() { egui::CursorIcon::Grabbing } else { egui::CursorIcon::PointingHand });
+                }
+                if !it.badge_only {
+                    painter.rect_filled(it.rect, RADIUS * s, p.popover);
+                    let stroke = if is_sel {
+                        Stroke::new(LINE_W, it.color)
+                    } else {
+                        Stroke::new(1.0, p.separator)
+                    };
+                    painter.rect_stroke(it.rect, RADIUS * s, stroke, egui::StrokeKind::Inside);
+                    let th = text_hash(a);
+                    let text_x = badge_rect.right() + 8.0 * s;
+                    let icon_rect = Rect::from_center_size(
+                        Pos2::new(it.rect.right() - (PAD + ICON_PX / 2.0) * s, badge_rect.center().y),
+                        vec2(ICON_PX, ICON_PX) * s,
+                    );
+                    let label_w = (icon_rect.left() - 6.0 * s - text_x).max(10.0);
+                    let lg = galley(ui, &mut view.galleys, (a.id, th, bucket, true), &a.label,
+                        theme::semibold(LABEL_PT * s), label_w, 1);
+                    painter.galley_with_override_text_color(
+                        Pos2::new(text_x, badge_rect.center().y - lg.size().y / 2.0), lg, p.text);
+                    theme::paint_icon(&painter, icon_rect, it.icon, it.color);
+                    if !a.body.is_empty() {
+                        let bw = it.rect.width() - PAD * 2.0 * s;
+                        let bg = galley(ui, &mut view.galleys, (a.id, th, bucket, false), &a.body,
+                            egui::FontId::proportional(BODY_PT * s), bw, BODY_ROWS);
+                        painter.galley_with_override_text_color(
+                            Pos2::new(it.rect.left() + PAD * s, badge_rect.bottom() + 6.0 * s), bg, p.secondary);
+                    }
+                }
+                let detached = a.detached || (a.target.is_none() && a.point.is_none());
+                let fill = if detached { p.warning } else { it.color };
+                painter.circle_filled(badge_rect.center(), BADGE_R * s, fill);
+                let mark = if detached { "!".to_owned() } else { it.n.to_string() };
+                painter.text(
+                    badge_rect.center(),
+                    Align2::CENTER_CENTER,
+                    mark,
+                    theme::semibold(BODY_PT * s),
+                    super::kit::ink_on(fill),
+                );
+                if badge.clicked() {
+                    *selected = Some(a.id);
+                    if mode == Mode::Full && !view.collapsed.remove(&a.id) {
+                        view.collapsed.insert(a.id);
+                    }
+                } else if resp.clicked() || resp.drag_started() {
+                    *selected = Some(a.id);
+                }
+                if resp.dragged() {
+                    let prev = view.drag.filter(|(id, _)| *id == a.id).map_or(V2::ZERO, |d| d.1);
+                    let d = resp.drag_delta();
+                    view.drag = Some((a.id, prev + V2 { x: f64::from(d.x), y: f64::from(d.y) } / cam.zoom));
+                }
+                if resp.drag_stopped()
+                    && let Some((id, off)) = view.drag.take()
+                    && off != V2::ZERO
+                {
+                    commit = Some((id, off));
+                }
+            }
+        });
+    commit
+}
+
+fn pill(ctx: &egui::Context, ed: &Editor, view: &mut AnnotationsView, canvas: Rect, mode: Mode) {
+    let chord = shortcuts::chord_text(shortcuts::Action::ToggleAnnotations);
+    let text = if mode == Mode::Hidden {
+        format!("Annotations off · {chord}")
+    } else {
+        format!("Annotations on · {} · {chord}", ed.doc.annotations.len())
+    };
+    let display = ed.active_template(ed.active_page).display;
+    egui::Area::new("annotations-pill".into())
+        .order(egui::Order::Middle)
+        .fade_in(false)
+        .pivot(Align2::CENTER_BOTTOM)
+        .fixed_pos(Pos2::new(canvas.center().x, canvas.bottom() - PILL_LIFT))
+        .show(ctx, |ui| {
+            let p = theme::pal(ui);
+            let r = egui::Frame::new()
+                .fill(p.popover)
+                .corner_radius(egui::CornerRadius::same(255))
+                .inner_margin(egui::Margin::symmetric(14, 6))
+                .show(ui, |ui| {
+                    ui.horizontal(|ui| {
+                        let (ir, _) = ui.allocate_exact_size(vec2(14.0, 14.0), Sense::hover());
+                        theme::paint_icon(ui.painter(), ir, Icon::Page, p.secondary);
+                        ui.add(egui::Label::new(
+                            egui::RichText::new(text).font(theme::semibold(theme::SECONDARY)).color(p.text),
+                        ).selectable(false));
+                    });
+                });
+            if ui.interact(r.response.rect, egui::Id::new("annotations-pill-click"), Sense::click()).clicked() {
+                view.cycle(display);
+            }
+        });
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn cycle_full_badges_hidden() {
+        let mut v = AnnotationsView::default();
+        assert_eq!(v.effective(Display::Full), Mode::Full);
+        v.cycle(Display::Full);
+        assert_eq!(v.effective(Display::Full), Mode::Badges);
+        v.cycle(Display::Full);
+        assert_eq!(v.effective(Display::Full), Mode::Hidden);
+        v.cycle(Display::Full);
+        assert_eq!(v.effective(Display::Full), Mode::Full);
+        // Template default Badges starts there.
+        let mut v = AnnotationsView::default();
+        assert_eq!(v.effective(Display::Badges), Mode::Badges);
+        v.cycle(Display::Badges);
+        assert_eq!(v.effective(Display::Badges), Mode::Hidden);
+    }
+
+    #[test]
+    fn route_shapes() {
+        let card = Rect::from_min_size(Pos2::new(0.0, 0.0), vec2(100.0, 40.0));
+        // Anchor right of the card, different y: H-V-H elbow from the right edge.
+        let r = leader_route(card, Pos2::new(300.0, 100.0));
+        assert_eq!(r.len(), 4);
+        assert_eq!(r[0], Pos2::new(100.0, 20.0));
+        assert_eq!(r[3], Pos2::new(300.0, 100.0));
+        assert_eq!(r[1].y, r[0].y);
+        assert_eq!(r[2].x, r[1].x);
+        assert_eq!(r[2].y, 100.0);
+        // Level anchor: straight.
+        assert_eq!(leader_route(card, Pos2::new(300.0, 20.0)).len(), 2);
+        // Left of the card: leaves the left edge.
+        assert_eq!(leader_route(card, Pos2::new(-50.0, 90.0))[0].x, 0.0);
+        // Below the card: vertical from the bottom.
+        let r = leader_route(card, Pos2::new(40.0, 200.0));
+        assert_eq!(r, vec![Pos2::new(40.0, 40.0), Pos2::new(40.0, 200.0)]);
+    }
+
+    #[test]
+    fn scale_is_bucketed_and_clamped() {
+        assert_eq!(scale_bucket(0.01), scale_bucket(0.6));
+        assert_eq!(scale_bucket(50.0), scale_bucket(1.5));
+        assert_eq!(scale_bucket(1.0), 10);
+    }
+
+    #[test]
+    fn edge_anchor_faces_card() {
+        let t = Rect::from_min_size(Pos2::new(100.0, 100.0), vec2(200.0, 50.0));
+        assert_eq!(edge_toward(t, Pos2::new(400.0, 500.0)), Pos2::new(300.0, 150.0));
+        assert_eq!(edge_toward(t, Pos2::new(0.0, 120.0)), Pos2::new(100.0, 120.0));
+        assert_eq!(edge_toward(t, Pos2::new(150.0, 0.0)), Pos2::new(150.0, 100.0));
+    }
+
+    #[test]
+    fn line_hit_test() {
+        let pts = [Pos2::new(0.0, 0.0), Pos2::new(100.0, 0.0)];
+        assert!(near_line(&pts, Pos2::new(50.0, 3.0)));
+        assert!(!near_line(&pts, Pos2::new(50.0, 20.0)));
+    }
+}
--- a/Show More
+++ b/Show More
Author	SHA1	Message	Date
Marcos Paulo	238249309f	chore: release 0.6.1 Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>	2026-10-22 05:37:26 -03:00
Marcos Paulo	35dc8aed8f	docs: agents and annotations guides, specs, mock-ups, 0.6.1 checks Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>	2026-10-22 05:37:20 -03:00
Marcos Paulo	73353dd4ca	feat: any agent via ACP, annotations with templates, chat fixes Chat: agents are found on the login-shell PATH, so apps launched from the Dock see claude, codex and Homebrew CLIs. A generic Agent Client Protocol backend runs OpenCode, Gemini CLI, Cursor, Pi (pi-acp) and others from a data registry, plus custom agents; papercraft tools are auto-approved only when announced and not destructive. New agent panel and Settings > Chat layout, sign-in card, several @ selections, no install instructions. Fixes Send silently doing nothing when the CLI path was set in Settings. Annotations: numbered notes with leader lines that explain a design. Categories drive the look; templates (project default, per-page) choose which kinds are used. Annotate tool (N), side view, Customize, inspector section, Annotate with AI, view modes (Cmd+Shift+A). MCP: annotate (batched), get/update/delete, get/set_annotation_template; notes appear in get_design_spec and get_jsx and in agent-run review and revert. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>	2026-10-22 05:37:20 -03:00
Marcos Paulo	33a0e265b8	chore: release 0.6.0 Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>	2026-10-21 22:43:18 -03:00
Marcos Paulo	45f197250b	docs: Chat mode guide, spec, mock-ups and end-to-end screenshots Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>	2026-10-21 22:43:11 -03:00
Marcos Paulo	13bc2d582e	feat: Chat mode with Claude Code, Codex and generic API endpoints A Design \| Chat layout (Cmd+J): a chat column next to the live canvas. Agents run through PaperCraft's own tools, so agent runs, undo, review and revert work as for any MCP client. The thread shows streamed text, reasoning, tool cards grouped into steps, the agent's plan, approvals for destructive tools, checkpoints with Restore to here, run cards and usage. Chats are saved in the project under chats/. Backends: Claude Code (claude -p stream-json) and Codex (codex exec --json) with the app's MCP server, using their own logins; or any API endpoint in Anthropic Messages or OpenAI Chat Completions format with a key kept in the OS keychain. Settings > Chat configures them. Also: the offline CLI no longer saves a camera fitted to a fake window, and top-level shapes without a position go to the next free spot. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>	2026-10-21 22:43:11 -03:00