Clarify Gradient Overlay source loss when saving styles

docs/control-protocol.md

@@ -67,7 +67,7 @@ The transport is `apps/photocraft/src/control_server.rs`, and the handlers are i
   - The shell's own dialogs (Window › Workspace › New Workspace / Delete Workspace, View › Pixel Aspect Ratio › Custom Pixel Aspect Ratio…, View › Show › Show Extras Options…, View › 32-bit Preview Options…) are listed in `ui.inspect`'s `dialogs` with the id `"shell"` (at most one is open). `ui.dialog.set`, `ui.dialog.confirm` and `ui.dialog.cancel` take `{"dialog": "shell"}`; OK runs the dialog's command and keeps the dialog open if it fails
   - The unsaved-changes prompt (closing a document, Revert, quitting with unsaved work) is listed in `ui.inspect`'s `dialogs` with the id `"discard"` while it is up: `fields` gives the waiting `command` (`file.close`, `file.exit`…), the `document` it asks about, how many are `remaining`, and its `choices`. `ui.dialog.confirm` takes `{"dialog": "discard", "choice": "save" | "dontSave" | "cancel"}` (default `save`; Revert takes `dontSave` or `cancel`) and answers it as the window's buttons do, one document at a time; `ui.dialog.cancel` with `{"dialog": "discard"}` cancels it. Save of an untitled document opens the save dialog first, so the reply's `fileDialog` is true and the prompt stays open until that is answered.
   - Layer Style (`layerStyle {effect?}` opens on that effect kind): the fields hold the dialog's whole state, so agents read and drive it like a user. `effects` lists every effect instance in the layer's order as `{id, kind, on, params, fx}` (`fx` is the effect snapshot the dialog loaded; OK edits that snapshot with `params`, so anything the dialog doesn't model survives). `selected` picks the page (`blendingOptions` or an instance id), `preview` (default on) gates the live canvas preview, `p:blendingOptions` edits blend mode/opacity/fill opacity, and `patternList` names the usable patterns. OK replaces the layer's effects in one step (`layer.layerStyle.replace`); Cancel discards. "New Style…" saves the pending state via `style.presets.new {effects}`, a swatch click applies a style preset, and Make/Reset Default use `layer.layerStyle.makeDefault` / `layer.layerStyle.defaultFor`
-  - Gradient Overlay exposes `params.method` (`smooth`, `perceptual`, `linear`, `classic`). `custom` denotes an existing curve without a recorded method and preserves it. Choosing a method retains the full source colour-stop list; later endpoint edits rebuild the colour curve using that method. The source stops, smoothness and method survive dialog reopening, undo/redo, style presets and native `.pcraft` saves. PSD export continues to write the baked appearance; reopening that PSD shows Custom because editable interpolation metadata is not exported yet. Opacity interpolation and the multi-stop editor are separate work.
+  - Gradient Overlay exposes `params.method` (`smooth`, `perceptual`, `linear`, `classic`). `custom` denotes an existing curve without a recorded method and preserves it. Choosing a method retains the full source colour-stop list; later endpoint edits rebuild the colour curve using that method. The source stops, smoothness and method survive dialog reopening, undo/redo and native `.pcraft` saves. Saving a style preset through "New Style…" may lose the multi-stop source curve: it passes only params to `style.presets.new`, and `effect_from_params` rebuilds the effect from the default gradient. PSD export continues to write the baked appearance; reopening that PSD shows Custom because editable interpolation metadata is not exported yet. Opacity interpolation and the multi-stop editor are separate work.
   - Preferences (`ui.menu.invoke {id: "edit.preferences.interface"}`) exposes the sections in its `values` field. Apply (`ui.dialog.apply`) and OK (`ui.dialog.confirm`) on Preferences are refused over control because automation denies whole-preferences updates and filesystem-bearing preference sections. A refused `ui.dialog.apply` returns an error and keeps the dialog open; a refused `ui.dialog.confirm` returns an error but closes and removes the dialog. `ui.dialog.cancel` closes the dialog without saving. Individual safe preferences can instead be changed with `engine.execute` using `prefs.set` (e.g. `{"command": "prefs.set", "params": {"path": "interface.showTooltips", "value": false}}`). Settings marked for the next launch still require a restart.
   - Edit › Fill… (`ui.menu.invoke {id: "edit.fill"}`, Shift+F5, Shift+Backspace) opens the Fill dialog; its fields are `edit.fill`'s params (`contents`, `color`, `pattern`, `colorAdaptation`, `mode`, `opacity`, `preserveTransparency`), and OK remembers them in the preferences (`dialogs["edit.fill"]`).
   - Save for Web (`ui.menu.invoke {id: "file.export.saveForWebLegacy"}`) is resizable with independently scrolling settings. Dialog fields `__view` (`original|optimized|2up|4up`), `__zoom` (`null` = Fit, otherwise a factor; 1 = 100% in physical display pixels), and `__center: [u,v]` control the shared preview navigation. `__previewRects` reports pane rectangles in screen points. Drag a preview to pan, scroll/pinch to zoom at the pointer, or double-click to fit. GIF/PNG-8 expose `colorTable: ["#rrggbb", …]` (opaque source entries) and `colorTableEdits: {"0":"#rrggbb", …}` (zero-based replacements after quantization). A swatch opens a color picker; edits update the preview and saved file without remapping pixel indices or changing the document. Reset clears replacements. Changing palette/size/matte/transparency settings regenerates the table and clears index-based edits. Previews and generated tables use a bounded 2048-pixel proxy; full-size export uses that explicit table unchanged. `__paletteApproximate` reports proxy-derived palette generation, and enlarged proxy previews are labelled. The engine export command accepts the same table/edit parameters; its no-path estimate returns the source `colorTable` and `transparentIndex` as well as size statistics. Opening a new dialog does not carry a previous image's table across.