# Control protocol

Shape stroke defaults are drivable with `ui.set {shapeStroke: {width, align, cap, join,
miterLimit, dashes, dashOffset, opacity}}`; partial fields merge, null disables the stroke.
Values use the existing `shape.edit` names and units. Colour uses `tools.setColors`.
`ui.inspect` exposes `toolOptions.shape_stroke`, `stroke_width`, and `strokeEditor`.
Stroke Options applies valid UI edits immediately; `strokeEditor` is the open editor state,
not an uncommitted document preview. Escape/outside clicks close it without reverting edits.
See [Shape stroke options](shape-strokes.md) for limits, preview and persistence behavior.

The desktop app listens on `127.0.0.1:<port>` (loopback only). Start it with a token file so the credential is not exposed in the process command line:

```sh
photocraft --control 7878 --control-token-file /private/path/photocraft-control.token \
  --automation-read-root /work/project --automation-write-root /work/project
```

If the file does not exist, PhotoCraft creates it with a fresh 256-bit token. On Unix the new file is mode `0600`; on Windows, protect it with an appropriate user-only ACL. An existing file is reused. If neither a token nor token file is configured, PhotoCraft generates a token for that launch and writes it to standard error. `PHOTOCRAFT_CONTROL_TOKEN` and `PHOTOCRAFT_CONTROL_TOKEN_FILE` are the environment-variable equivalents. A flag wins over its variable and an empty variable counts as unset; with `--control` (or `PHOTOCRAFT_CONTROL_PORT`), a token together with a token file, from flags or variables, is a usage error (exit status 2). Without it no token is read, so the pair is ignored.

The first request on every TCP connection must authenticate. No other method is dispatched before this succeeds. There are two ways; a refused frame gets `{"ok": false, "error": "authentication required"}` and the connection is closed.

**Challenge authentication** (what `photocraft-cli mcp --bridge` uses) never sends the token, and the server proves it holds the token before the client reveals anything derived from it, so a process that took the port (the app is not running yet, or has exited) learns nothing:

```json
{"id": 1, "method": "auth.challenge", "params": {"clientNonce": "<64 hex: 32 fresh random bytes>"}}
{"id": 1, "ok": true, "result": {"serverNonce": "<64 hex>", "serverProof": "<64 hex>"}}
{"id": 2, "method": "auth", "params": {"proof": "<64 hex>"}}
{"id": 2, "ok": true, "result": {"authenticated": true}}
```

Both proofs are lowercase hex HMAC-SHA256, keyed by the token's 64 lowercase hex characters (as ASCII), over `<label>\n<clientNonce>\n<serverNonce>` with both nonces lowercase and `\n` a newline byte (0x0A). The label is `photocraft-control-v1 server` for `serverProof` and `photocraft-control-v1 client` for `proof`. The client checks `serverProof` and, when it does not match, closes the connection without sending `auth`. After a challenge only `auth {proof}` is accepted.

**Token authentication** is the original single frame, still accepted for scripts:

```json
{"id": "auth", "method": "auth", "params": {"token": "<64 hexadecimal characters>"}}
```

It sends the token to whatever holds the port, so a client should use it only when it knows the app is the listener. PhotoCraft's own bridge never falls back to it.

Authenticate once per connection. A later `auth` or `auth.challenge` frame on the same connection gets `{"ok": false, "error": "already authenticated"}` and the connection keeps serving.

After the successful authentication reply, each request is one JSON line:

```json
{"id": 1, "method": "ui.inspect", "params": {}}
```

Each reply is one JSON line with the same `id`:

```json
{"id": 1, "ok": true, "result": { ... }}
{"id": 2, "ok": false, "error": "unknown tool `foo`"}
```

The desktop server waits up to 60 seconds for a reply. A request still queued at that deadline is rejected before dispatch; a timeout does not cancel work that has already started. The two timeouts read differently, both starting with `timeout`: a request that was never dispatched (still queued at the deadline) says `timeout: not run` and is safe to re-send, while `timeout: no reply in 60s` means the command was dispatched and may still be running and still apply, so check the document before re-sending it. The timeout error names the likely causes: the command may still be running, or the request was queued while the window was not drawing frames — on Wayland the frame update (and with it the control drain) only runs on compositor frame callbacks, so a display that is asleep or a fully occluded window makes every request time out while the app itself is healthy.

The transport is `apps/photocraft/src/control_server.rs`, and the handlers are in `crates/ui-egui/src/control.rs`. The MCP server (`photocraft-cli mcp --bridge 127.0.0.1:<port>`, crate `photocraft-automation`) wraps this same protocol. See [MCP bridge](#mcp-bridge) below.

## Methods

- `engine.execute {command, params}`: run any engine or UI command by id. Engine commands run directly with their default params and never open a dialog. Use `ui.menu.invoke` for menu-click behaviour, which opens a command's dialog when no params are given. `params` must be a JSON object (omit it or pass `null` for none); an array, string, number or boolean is an error naming the command, in every transport (control channel, `serve`, MCP and the CLI)
- `engine.commands`: list commands with enablement; the `result` is a JSON array of command objects (see [Command list replies](#command-list-replies))
- `ui.inspect`: full UI state (tool, panels, views, dialogs, windows, window size). The menu tree is not included; use `ui.menu.list`. `brushPicker` is `null` while closed and `{pos: [x, y], size: [w, h]?, list: {collapsed, filter, renaming, showName, showStroke, showTip, scale}}` while the Brush Preset picker is open (coordinates in screen points; `size` is the picker's content size once its corner grip was dragged, `null` before that, and the drag remembers both dimensions; the three `show*` flags pick the parts of each preset's card — at least one is always on; `scale` is the footer slider, 0.15–2 with 1 the standard, multiplying the cards' width and height — the heights stop at half size and the name and tip-size text hold their 1.0 size — and dropping the tips' size numbers at 0.40 and below; the parts and the scale are remembered across restarts, while the search, collapsed groups and a rename in progress are not). `view` holds the View/Window/Type preferences: `screen_mode`, `extras`, `show` and `snap_to` flags, `flip_horizontal`, `arrange` (Window › Arrange layout), pixel aspect, font preview size, language options. `perf.timings.gpuInfo` holds the graphics adapter, backend, driver, the backend chosen at launch and why, the canvas renderer (`gpu`/`cpu`) and, after a device loss, `lost` (`help.systemInfo` returns the same as `info`). `perf.renderPath` says why the active document is drawn on the CPU: `current` is `null` on the GPU, else `{doc, kind, detail}` (`kind` is one of `overBudget`, `canvasTooLarge`, `compositorBuild`, `deviceLost`, `gpuError`, `unsupported`, `adjustPreview`, `viewTransform`, `softwareAdapter`, `cpuMode`; `detail` is the English reason, with the working set and budget for `overBudget`), and `history` holds the last 32 changes, oldest first (`{t, doc, kind, detail}`, `kind` `null` for back on the GPU, `doc` the changed document's id, or 0 for a change to every document). An adjustment dialog's CPU proxy preview has its own slot: `current` reports it (`adjustPreview`) only when neither the window nor the canvas has a reason, it isn't recorded while the whole window is off the GPU, and its history entries always have `kind` `adjustPreview`, with `detail` `null` when the preview stops using the proxy (never read as back on the GPU). `perf.timings.gpuFallback` is `current`'s `detail` as text. `perf.slowFrames` lists the last 64 frames over 50 ms, oldest first, each with its stages in ms: `t` (start), `frameMs`, `inputMs` (raw input to the UI build, commands excluded), `commandMs` and `command` (the last command run since the previous frame), `damageMs` (damage tracking and GPU memory budgeting), `compositeMs`, `uploadMs`, `gpuMs` (the GPU's own composite time, or `null`), `presentMs` (the previous frame's tessellation and submission, or `null`), `refresh` and `refreshPx` (the canvas redraw's kind and pixels) and `path` (`gpu` or `cpu`). The web build keeps them too (its clock is `performance.now()`) and logs them to the browser console
- `ui.set {tool?, panels?, dockTabs?, dock?, dockWidth?, colorPanel?, maskTarget?, vectorMaskTarget?, filterMaskTarget?, selectionMode?, zoom?, center?, rotation?, fit?, theme?, brushSize?, brushSection?, brushTab?, brushesView?, brushPicker?, brushPickerName?, brushPickerStroke?, brushPickerTip?, brushPickerScale?, gradientBlendMode?, gradientClassic?, shapeStroke?}`: change UI state; any other field is an error, checked before anything changes (`zoom` is the canvas zoom where 1 = 100%, one document pixel per physical display pixel, so a scaled display doesn't magnify the image; `theme` is `pro`, `proMedium`, `studio`, `studioLight` or `classic`; `selectionMode` is the selection tools' options-bar mode, 0 New, 1 Add, 2 Subtract, 3 Intersect; `brushSection` indexes the Brush Settings sections, `brushTab` 0 = Brush Settings, 1 = Brushes; `brushesView` is `list` or `grid` for the Brushes panel; `brushPickerName`, `brushPickerStroke` and `brushPickerTip` are the Brush Preset picker's card parts (booleans, at least one on), and `brushPickerScale` its footer card-scale slider (0.15 to 2, 1 the standard); `brushPicker` is `[x, y]` in screen points to open the Brush Preset picker there (as a right-click with a painting tool does) or `null` to close it, and picking a preset in it is `tools.setBrush {"preset": name}`; `dock` is `{order: ["layers", …], heights: {"properties": 180}, collapsed: ["color"], tabOrder: {"layers": ["Paths", "Layers", "Channels"]}}`, the right-dock groups top to bottom, their heights in points, the groups collapsed to their tab strip and each group's tab order left to right by panel name (a group left out keeps its default order, unknown names are ignored and tabs not listed follow in their default order; `dockTabs` keeps indexing tabs in their default order); `dockWidth` sets the whole end dock's width in points, requested within 250..max(520, window width − 400): the change from the current width is shared equally among the columns, within their minimums and iconic caps (a column that reaches one passes the rest to the others), so those determine the achieved model width; `dockWidth` is the requested model width, and in a window too narrow for it, in either layout, the drawn dock may be narrower, clipped to its panel so the toolbar and the canvas's 200 points stay clear, and it is drawn at the stored width again when the window grows; `colorPanel` is `{background?, mode?, ramp?, webSafeRamp?}`, merged into the Color panel's state: `background` is whether it edits the background colour, `mode` its panel-menu display (`hueCube`, `brightnessCube`, `colorWheel`, `grayscaleSlider`, `rgbSliders`, `hsbSliders`, `cmykSliders`, `labSliders` or `webColorSliders`), `ramp` the colour ramp under the sliders (`rgbSpectrum`, `cmykSpectrum`, `grayscaleRamp` or `currentColors`) and `webSafeRamp` Make Ramp Web Safe; `maskTarget` targets the active layer's mask, which, like Photoshop, swaps in the foreground/background pair kept for masks (white/black until one is picked) and swaps the pixels' pair back when the pixels are targeted again; `filterMaskTarget` targets the active smart object's filter mask (an error without smart filters), so painting, fills, filters and adjustments edit it (`"target":"filterMask"`) while Move and Edit › Transform still act on the smart object)
  - `typeTransform` is `null` outside a temporary Ctrl/Cmd Type-tool drag. During a drag it reports its source document/revision, original affine, oriented `frame` (layer, local bounds, document-space corners and pivot), and captured `gesture`. Drive it with `ui.pointer` and `command: true` at `down`; `move`/`up` may release the modifier. The document/history remain unchanged during preview, and `up` applies one `type.edit` within `textEdit`'s session. Pressing Escape during the drag cancels only the preview. This pointer state is never restored from saved UI state.
- `ui.menu.invoke {id, params?, wait?}` / `ui.menu.list`: activate a menu item by id; list the menu tree. A menu item that starts a background job (a filter without a dialog, such as Blur More) replies with the job's result once it has been applied; with `"wait": false` the reply is `{job, pending: true}` at once. Window ends with the open documents as `window.document.<index>` (tab order, the active one checked, #2991); invoking one brings that document to the front and replies `{document: index}`. Camera Raw and the full-window workspaces (Liquify, Content-Aware Fill, Filter Gallery, Adaptive Wide Angle) are modal: while one is open, `ui.menu.invoke` refuses every other menu item ("menu command is unavailable while a modal dialog is open") and accepts only that workspace's own `{"ui": {...}}` requests (`filter.liquify`, `edit.contentAwareFill`, `filter.filterGallery`, `filter.adaptiveWideAngle`, `filter.cameraRaw`; `params` must hold only the `ui` object), so finish it with `{"ui":{"commit":true}}` or `{"ui":{"cancel":true}}` first. Those requests are refused too while a dialog, an unsaved-changes prompt or a crop that blocks the command is open: resolve that first, then commit or cancel the workspace. `ui.menu.list` reports the same gate: an item the modal state refuses is listed with `enabled: false`. `engine.execute` is not a menu click and is not gated
- `ui.set` also accepts `gradientBlendMode` (a layer blend mode name, such as `Difference`) and `gradientClassic` (boolean) for the Gradient tool options bar.
- `ui.set` also accepts `moveShowTransform` (boolean), the Move tool's Show Transform Controls checkbox (`ui.inspect` › `toolOptions.move_show_transform`). With Move active and the controls visible, a primary `ui.pointer` down on a handle or in the rotation zone starts the same Free Transform session as the canvas, framing all selected non-Background layers. `move` and `up` drive the existing preview; `ui.key {"key":"Enter"}` commits one "Free Transform" history step. A press inside the box keeps the ordinary Move behavior. Hidden or disabled controls do not start a transform. An invalid value rejects the whole `ui.set` request before any fields change.
- `ui.set` also accepts `camTransformOnDrop` (boolean), the Content-Aware Move tool's Transform On Drop checkbox: a drop then puts a scale/rotate box on the patch (`ui.inspect` › `camTransform`: its document/revision, drag `offset` and `frame`), driven with `ui.pointer` (handles as Free Transform's; outside the box rotates), committed with `ui.key Enter` (one `paint.contentAwareMove` with `scaleX`, `scaleY`, `rotate`) or dropped with `Escape`.
- `ui.set` also accepts `tileGrid` (boolean), a developer overlay of the active layer's storage tiles: the tile grid over the document, every stored tile filled and labelled `tx,ty`, tiles with identical pixels in a shared colour and unique ones in blue. It has no menu item and View › Extras doesn't hide it. `ui.inspect` reports it as `view.tile_grid`.
- `ui.set` also accepts `strokeTrace` (`true`, `false`, `"stderr"` or `"off"`): turn the stroke latency trace on or off at runtime; each stroke's summary is in `ui.inspect` `perf.strokeTrace`. A CSV file of every frame is set only at launch (`PHOTOCRAFT_STROKE_TRACE=<file.csv>` / `--stroke-trace <file.csv>`): the control channel doesn't write files outside the automation write root
- `ui.set` also accepts `layerFilter` (#5048), the Layers panel filter row: `{by?, kinds?, name?, effect?, mode?, attribute?, color?, smart?}`, any subset. `by` is `kind`, `name`, `effect`, `mode`, `attribute`, `color`, `smartObject`, `artboard` or `group` (the filter-type dropdown); `kinds` lists the Kind toggles that are on (`pixel`, `adjustment`, `type`, `shape`, `smart`); `name` matches part of a layer name, ignoring case; `effect` (#10880) is `bevelEmboss`, `stroke`, `innerShadow`, `innerGlow`, `satin`, `overlay` (Color, Gradient or Pattern Overlay), `outerGlow` or `dropShadow`, and lists the layers with that effect turned on; `mode` is one of the 27 layer blend modes (`Multiply`, `Screen`), not Pass Through, which the Mode list doesn't offer (#10878); `attribute` (#10881) is `visible`, `locked`, `empty`, `linked`, `clipped`, `layerMask`, `vectorMask`, `layerEffects` or `advancedBlending`, or one of their opposites `notVisible`, `notLocked`, `notEmpty`, `notLinked`, `notClipped`, `noLayerMask`, `noVectorMask`, `noLayerEffects`, `noAdvancedBlending`; `color` is a layer colour label id (`none`, `red`, `orange`, `yellow`, `green`, `seafoam`, `blue`, `indigo`, `magenta`, `fuchsia`, `violet`, `gray`; #5898); `smart` lists the Smart Object toggles that are on (`linked`: linked to a file, `missing`: linked to a file that was not there when the app last looked, `embedded`). Kind, Name and Smart Object filter only once a toggle is on or text is typed; Effect, Mode, Attribute and Color always filter, by Bevel & Emboss, by Normal, by Visible and by no colour at first, as in Photoshop. Artboard has no field of its own: it lists the artboards that hold the selected layers, with everything inside them (closed groups stay closed), and does not filter when nothing is selected or a selected layer is in no artboard. Group (#10883) has no field of its own either and filters at once: it lists every group that is not an artboard with everything inside it (the groups inside an artboard too), and hides the layers that are in no group; each group stays open or closed as it is. Fields left out keep their value; a bad one is an error and changes nothing.
- `select.findLayers` (#10884, Select › Find Layers) filters the Layers panel by Name and selects none of the matches; as with any filter, a selected layer the filter hides is deselected (#10879). With `name` it sets the Name text; without it the text is kept. Through `engine.execute` or an action step that is all; through the menu, the shortcut or `ui.menu.invoke` without `name`, the Layers panel is also shown and its Name field takes the keyboard focus with the text selected (unless Filter Options › Hide hid the filter row, which stays hidden). The reply lists the ids of the layers the Name text matches in `selected` (trimmed, ignoring case: a blank text lists every layer, a text nothing matches none) and the Name filter applied in `layerFilter` (`{by: "name", name}`).
- `ui.set` also accepts the Histogram panel: `histogramPanel` `{view?, channel?, showChannelsInColor?, showStatistics?, source?}` (any subset, kept with the preferences): `view` is `compact`, `expanded` or `allChannels`; `channel` is `composite`, `red`, `green`, `blue`, `cyan`, `magenta`, `yellow`, `black`, `a`, `b`, `luminosity` or `colors` (one the document's mode lacks shows as its composite); `source` is `entireImage`, `selectedLayer` or `adjustmentComposite` (Entire Image is counted in Compact View, when the document has one layer, or when no adjustment layer is selected for Adjustment Composite). `histogramRange` is `[from, to]` (levels 0..255) or `null`: the dragged tonal range whose Count and Percentile the statistics show. `histogramRefresh: true` is Uncached Refresh: the current state is recounted at cache level 1. `ui.inspect` › `histogram` reports the options, the channel and source as they apply, the channels the document offers, whether the shown histogram is `current` (counted for the document's revision, source and cache level the panel wants now), its `cacheLevel`, `maxCacheLevel` (Preferences › Performance › Cache Levels), `preview` (an adjustment's preview is counted) and `stats` (`mean`, `stdDev`, `median`, `pixels`, `level`, `count`, `percentile`, `clipped` percent at 0 and 255). Histograms are counted while the panel is shown.
- Each painting tool keeps its own brush, as in Photoshop: `tools.setBrush` and `ui.set {brushSize}` change the active tool's brush, and switching tools swaps in that tool's own (size, hardness, mode, opacity, flow, dynamics, smoothing). A tool used for the first time starts from the brush in hand. The colours, the erase flag and the stroke seed stay shared. So `ui.set {tool: "eraser", brushSize: 12}` sets the Eraser's size, and `ui.set {tool: "brush"}` afterwards brings the Brush's own size back.
- Brush Pose's `pose.overrideTiltX` and `pose.overrideTiltY` are independent booleans. For example, `engine.execute {"command":"tools.setBrush","params":{"pose":{"enabled":true,"tiltX":45,"overrideTiltX":true,"overrideTiltY":false}}}` fixes X at 45° while Y follows the stylus. Pose tilts are degrees (±90); the Brush Settings panel displays percentages (±100). Old stored `overrideTilt` values migrate to both axes. In command patches, `overrideTilt` sets both axes unless an explicit axis field in the same patch overrides it. `brush.get` includes both axis flags and the legacy combined readback (`overrideTilt` is true only when both flags are true). Axis-only journals omit that derived combined key so replay retains the other axis. Present flag values must be booleans; null and other types return an error.
- `ui.set` also accepts the Eyedropper options bar (#1649): `eyedropperSampleSize` (`"point"` or 1, 3, 5, 11, 31, 51, 101: the side of the averaged square, shared by the Eyedropper, a painting tool's Alt-click eyedropper, the Curves/Color Picker eyedroppers and the Info panel), `eyedropperSample` (`current`, `currentAndBelow`, `all`, `allNoAdjustments`, `currentAndBelowNoAdjustments`) and `eyedropperRing` (boolean, Show Sampling Ring). `ui.inspect` reports them under `toolOptions` (`eyedropper_size`, `eyedropper_sample`, `eyedropper_ring`). The engine command `document.sampleColor {x, y, size, sampleLayer}` returns the colour such a sample picks, as four floats 0..1 (not 0..255).
- `ui.set` also accepts the Crop tool's overlay menu (#1919): `cropOverlay` (`thirds`, `grid`, `diagonal`, `triangle`, `goldenRatio`, `goldenSpiral`), `cropOverlayShow` (`always`: the whole time a crop is pending, the default, as in the reference application; `auto`: only while the crop box is dragged; `never`) and `cropOverlayOrientation` (0..3; Triangle has two orientations and Golden Spiral four, the others ignore it). `ui.inspect` reports them under `toolOptions` (`crop_overlay`, `crop_overlay_show`, `crop_overlay_orientation`). In the app, O cycles the overlay and ⇧O its orientation while the Crop tool shows a box.
- `ui.set` also accepts the Pen tools' options bar (#1397): `penMode` (`path` or `shape`) and `penPathOp`, the Path Operations menu (`newLayer`, `combine`, `subtract`, `intersect`, `exclude`): how the next Pen, Freeform Pen or Curvature Pen path joins the selected shape layer (Shape mode; `newLayer` makes a new one) or the targeted vector mask, selected path or Work Path (Path mode, where `newLayer` combines). `ui.inspect` reports them under `toolOptions` (`vector_mode`, `pen_path_op`). Merge Shape Components is the engine command `path.mergeShapeComponents` (work, saved or `layer` path) or `layer.combineShapes.mergeShapeComponents` (shape layers).
- `ui.set` also accepts `cropFill` (`background`, the Fill dropdown's first entry, which reads Background (default), or Transparent (default) with Delete Cropped Pixels off, or `contentAware`), the Crop tool's Fill dropdown (#3823, #10872): with `contentAware`, committing a turned or extending frame passes `contentAware: true` to `image.crop`, which fills the area the image doesn't cover from its surroundings. `ui.inspect` reports it as `toolOptions.crop_content_aware`.
  Both gradient modes use the current preset, including its opacity stops. Select `Foreground to Transparent` through `gradient.presets.select`, or pass custom `stops` and `transparency: [[0,100],[1,0]]` (location 0..1, opacity 0..100). Use `applyToLayer: false` to edit only the tool preset. Classic gradient drags dispatch `paint.gradient` without overriding them.
- `ui.set` also accepts the Crop tool's gear menu (#1919) as `cropShield`, an object patching any of `show_cropped_area` (Show Cropped Area; off hides everything outside the box behind the canvas colour, H in the app), `enabled` (Enable Crop Shield), `color` (`matchCanvas`, the pasteboard colour, or `custom`), `custom_color` (`[r, g, b]`, 0..255), `opacity` (0..100, default 75), `auto_adjust` (Auto Adjust Opacity: half the opacity while the box is dragged), `classic_mode` (Use Classic Mode, default off: the box turns and moves over the image; off is Photoshop's default mode, where the box stays upright and the view turns and pans the image behind it while the Crop tool shows a frame, P in the app; in both modes picking the tool turns a rotated view upright about its centre, Classic Mode keeping the camera upright with the frame drawn turned, and the view stays upright after a commit or cancel; Classic Mode greys out Show Cropped Area, which then acts as on, and Auto Center Preview) and `auto_center_preview` (default on: in default mode a box being resized keeps its centre where it is on screen, also after a pan, a drawn one moves to the middle of the canvas, and X re-centres it; a move never re-centres the box). `ui.inspect` reports it as `toolOptions.crop_shield`. The pending frame (`crop_rect`, `crop_angle`: its turn on the image) and the `image.crop` a commit runs are the same in both modes.
- The contextual task bar (#10890) is the small floating bar under the Crop tool's frame: a grip, the crop preset dropdown (the options bar's), Straighten, a ⋯ menu (Hide bar, Reset bar position, Pin bar position) and, while a crop is pending, Cancel and Done (the options bar's cancel and commit). It sits centred under the frame with its top 11 points below the frame's bottom edge, follows the frame, and stays inside the canvas area; dragged by its grip or pinned, it stays where it is. `ui.inspect` › `taskBar` reports `enabled` (Window › Contextual Task Bar, `window.panel.contextualTaskBar`), `visible` (a bar shows now), `rect` (its screen rect `[x0, y0, x1, y1]` in points, `null` while hidden), `pinned` and `at` (its top-left in points from the canvas area's top-left once dragged or pinned, `null` while it follows the frame). `ui.set {"panels": {"context_task_bar": false}}` hides it (as Hide bar does) and `true` shows it; `ui.set {"panels": {"task_bar": {"pinned": true}}}` pins it where it is (`"at": null` with it first puts it back under the frame), `{"pinned": false, "at": null}` is Reset bar position, and `at: [x, y]` places it; a field left out keeps its value. Both are kept with the panel layout across restarts.
- `ui.dialog.open {kind, fields?}` (kinds `newDocument`, `about`, `layerStyle {effect?}`, `colorPicker {target: foreground|background}`, `command {command}` (`layer.new.group` / `layer.new.groupFromLayers` open the New Group dialog: fields `name`, `color`, `mode`, `opacity`), `newCropPreset` / `deleteCropPreset`: the Crop tool's New / Delete Crop Preset… dialogs, fields `name` and `selected: [names]`; crop presets are `crop` tool presets, so `tool.presets.new/list/edit {"tool":"crop"}` drive them too) / `ui.dialog.set {dialog, field, value}` / `ui.dialog.confirm {dialog, wait?}` / `ui.dialog.cancel {dialog}`. Like `ui.menu.invoke`, `ui.dialog.confirm` waits for a background job its command starts (a filter dialog's OK) and replies with the result; `"wait": false` replies `{job, pending: true}` at once
  - A Layer Style color field opens the shared picker with `ui.dialog.open {"kind":"colorPicker","parent":12,"effect":"fx2","field":"color"}`. `parent` is the Layer Style dialog id; `effect` is its effect instance id. `field` must be one of that instance's color parameters (`color`, or `from`/`to` for Gradient Overlay). The picker previews over the pending style without changing the document. Picker OK changes only the parent parameter; Cancel discards the preview. Confirm the parent afterwards to apply the style. Parent confirmation is refused while its picker is open; parent cancellation closes both. The binding is exposed in `ui.inspect` as `__layerStyleColor`; changed/closed targets or a document switch invalidate it.

  - Gradient Overlay color stops use `colorPicker {parent, effect, field: "stops", stop: index}`; the stop must exist.
  - `ui.dialog.open {kind:"colorPicker", textStyle:{kind:"character"|"paragraph", id:u32}}` opens the shared Color Picker for an explicitly enabled Color attribute in Style Options. It opens the matching style panel/editor after validation; inherited colors must first be enabled through the existing style command. The picker reports its bound document/revision/style under `__textStyleColor` in `ui.inspect`. Changes preview in an isolated document; OK runs the existing style `set` command once, Cancel changes nothing. Document edits/switches or closed/changed Style Options discard the picker. `textStyle` cannot be combined with `parent`, `effect`, `field` or `target`.
  - 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" | "saveAll" | "dontSave" | "dontSaveAll" | "cancel"}` (default `save`; Revert takes `dontSave` or `cancel`) and answers it as the window's buttons do, one document at a time. `saveAll` and `dontSaveAll` tick "Apply to All": they answer for every document still to ask about, and are listed in `choices` only while more than one is left. A document whose save is cancelled or fails is asked about again; `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.
  - A save dialog's answer that PhotoCraft changes, by giving a name without an extension the suggested file's or by lowercasing the extension (Preferences › File Handling › Lowercase Extension), opens a replace prompt when a file exists under the changed name: a dialog with `__replaceSaved`, `message`, `detail` and `path` (the file the save would replace). `ui.dialog.confirm` writes the file; `ui.dialog.cancel` ends the save without writing, as Cancel in the save dialog does. The file dialog counts as open until the prompt is answered. A name that differs only in letter case and reaches the same file (Windows and macOS by default) does not open it.
  - 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 all recorded source colour stops. If no source record exists (including baked PSD imports), choosing a method rebuilds from the two end colours, matching legacy command behaviour; the old curve stays unchanged until that choice. Later endpoint edits rebuild the colour curve using the recorded 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.
  - Gradient Overlay's `params.offset` is the gradient's centre as a fraction of the layer's bounds (`[x, y]`, `[0, 0]` centred, as the renderer takes it). With the dialog on a Gradient Overlay page, a drag on the image moves it by the pointer's movement over the layer's size, as a drag on a shadow page moves the shadow (#10763).
  - 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.
  - Select › Select and Mask… (`ui.menu.invoke {id: "select.selectAndMask"}`, Ctrl+Alt+R) opens Photoshop's workspace; `ui.inspect` reports it as `distort.selectAndMask`. Drive it with `ui.menu.invoke {id: "select.selectAndMask", params: {ui: {…}}}`: `tool` (`quick|refineEdge|brush|object|lasso|polygonalLasso|hand|zoom`), `mode` (`add|subtract`), `size`, `hardness`, `sampleAllLayers`, `hideView` (true shows the image without the view, as holding X does), `stroke: {points: [[x,y],…], alt?}` (a drag with the current tool in document px: Object Selection takes a click or the rectangle's corners, the lassos the polygon), `selectSubject`, `clearSelection`, `invert`, the settings (`view`, `opacity`, `showEdge`, `showOriginal`, `realTimeRefinement`, `highQualityPreview`, `overlayColor`, `indicates`, `radius`, `smartRadius`, `smooth`, `feather`, `contrast`, `shiftEdge`, `decontaminate`, `amount`, `output`, `remember`), `undo`, `redo`, `reset`, `waitPreview`, `commit` (OK: `select.refineEdge` with the workspace's `edits` and `refineStrokes`, one history step) and `cancel`. The reply describes the workspace (`edits`, `strokes`, `selectedProxyPixels`, `previewReady`, …).
  - 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"]`).
  - Image › Adjustments › Levels… (`ui.menu.invoke {id: "image.adjustments.levels"}`): `__clipping` (`"shadows"` or `"highlights"`; `null` turns it off) shows Photoshop's clipping display on the canvas instead of the preview, what the black or white Input slider clips. The app sets it while Alt and the mouse button are held on one of those sliders; it never reaches OK. The display shows only for RGB and Grayscale documents whose target is a raster layer's pixels, on the main canvas. Other targets (CMYK or Lab documents, a channel, mask or Quick Mask target, a non-pixel layer, a Smart Filter) accept the value and keep the normal preview.
  - 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. Image Size has `width` and `height` (px), `percent` and `resample` (`nearest|bilinear|bicubic|bicubicSmoother|bicubicSharper`, default `bicubic`); `__constrain` (default true at each opening) links the two sides in proportion. A side edit sets both sides and removes `percent`, which the export command otherwise applies first; a Percent edit sets both sides from it. Each opening starts at the document's full size, while `resample` is remembered with the encoding choices. The document is never resized.
  - A pixel tool pressed on a type, shape, Smart Object or fill layer (e.g. through `ui.pointer`) opens the "Rasterize?" prompt instead of painting: a dialog with `__rasterize` (`type|shape|smartObject|fill`), `message`, `layer`, `tool` and `at`. `ui.dialog.confirm` runs the `layer.rasterize.*` command only (`{"rasterized"}`; the click that opened the prompt is not replayed, as in Photoshop); `ui.dialog.cancel` does nothing.
  - Edit › Transform › Warp on editable type (`ui.menu.invoke {"id":"edit.transform.warp"}`, or the warp toggle of an open transform box) opens Warp mode with no prompt, as in Photoshop: the mesh can't be dragged or split, only the options bar's warp style, Bend, H and V apply, and the commit sets the layer's Warp Text in one step, so the type stays editable. Directly: `engine.execute {"command":"edit.transform.warp","params":{"style":"flag","bend":40}}` on a type layer. Distort and Perspective stay greyed for type.
- `ui.window.open {document?}` / `ui.window.close {window}`: extra document windows
- `ui.pointer {events: [{kind: down|move|up, x, y, pressure?, tiltX?, tiltY?, rotation?}], tool?, modifiers?, button?}`: drive the active tool in document coordinates (pressure 0..1, tilt in degrees -90..90, barrel rotation 0..360: a simulated pen). Modifier flags (`shift`, `alt`, `command`, `ctrl`, `space`) go either at the top level or grouped under `modifiers`; when `modifiers` is present, top-level flags are ignored. `space: true` holds Space (the Crop frame, marquee, lasso or shape being drawn then moves instead of growing). With the Crop tool in its default mode (Use Classic Mode off) a drag inside the box moves the image and one outside turns it, the view panning and turning with it; a drag's `move`/`up` points are read as the view showed the document at its `down`, so an `up` where the last `move` was changes nothing more. `command: true` with a painting, retouching, eraser, gradient, eyedropper or other non-selection tool makes the gesture the Move tool's, as holding ⌘ (Ctrl off the Mac) does in the app: a drag moves the active layer (the selected pixels when there is a selection), with `alt: true` as well it duplicates the layer first, and a click picks the layer under the point; the tool is unchanged afterwards. The Hand, Rotate View, Zoom, Crop, Slice, Path Selection, Pen, shape, Type and selection tools keep `command` for themselves. `ctrl: true` with `alt: true` and a brush tool is the on-canvas brush resize instead (in the app, Ctrl+Alt-drag off the Mac). `button: "right"` (or `"secondary"`) is the right button: with the Move tool (or `command: true` with any tool) it opens the canvas layer menu (`layerMenu` in `ui.inspect` lists the layers there, topmost first; select one with `layer.select`); with Marquee, Lasso, Magic Wand, Object Selection, or Pen, or with a Type tool on text being edited or on committed type, it opens a tool context menu (`canvasToolMenu` in `ui.inspect`, with ordered command ids, separators, and enabled states); with Zoom or Hand (or `space: true` alone, the Hand held over any tool) it opens the view menu there (Zoom In and Zoom Out keep the view centre with the non-temporary Zoom tool and Zoom Clicked Point to Center off; other cases retain their pressed-point behaviour; `view.fillScreen` is its Fill Screen row); with a painting tool it opens the Brush Preset picker, or erases with Preferences › Tools › Right-click with painting tools = erase. For a painting tool's Shift+right-click, see the Mode menu exception below. The menus open at the screen position of the pressed document point. Use `ui.context.choose {id}` for enabled tool-context actions. The Pen menu is documented in `docs/context-menu-parity.md`. `button` is `left` (default), `right`, `secondary` or `middle`, and an event's `kind` is `down`, `move` (default) or `up`. With a Color Picker as the top dialog, `down` and `move` sample the image into its new colour instead (its eyedropper, like a click on the canvas) and the tool is not driven. A `down`/`up` at the same point with the Rectangle, Ellipse, Triangle or Polygon tool opens Create Rectangle / Ellipse / Triangle / Polygon (Photoshop's click-to-size dialog); set its `width` and `height` (document pixels), `fromCenter`, `radii` [tl, tr, br, bl] (Rectangle) or `sides` and `starRatio` (percent, Polygon) with `ui.dialog.set`, then `ui.dialog.confirm` runs `shape.create` at the clicked point.
  - Magnetic Lasso (`tool: "magneticLasso"`): a `down`/`up` pair is a click. The first sets the first fastening point (its modifiers set the selection mode); later clicks fasten a point, or close the border on the first point. `move` events trace the border with or without a button held, fastening points by themselves; with `alt: true` a click draws a straight segment and a drag a freehand one. `ui.inspect` shows the border in progress under `magnetic` (`path`, `anchors`, `live`, `mode`). `ui.key` Enter closes it along the edges, Backspace removes the last fastening point, Escape cancels. To select along edges in one call instead, use the `select.magneticLasso` command with rough points around the shape.
  - Image › Adjustments › Curves on top, no eyedropper armed (#7325): a `down` with `command: true` adds a point on the curve the dialog shows (its Channel popup), at the pixel's tone (RGB: Rec. 709 luma; Gray: the mean) and at the curve's current output there, so the preview does not change; with `shift: true` as well, one point on each of Red, Green and Blue at that channel's value. It samples the merged image like the eyedroppers, never moves an existing point (a point already within 2 levels is selected instead, a 16-point curve takes no more), and the tool is not driven. Nothing is added with a pencil-drawn curve, in Lab or CMYK, or with a mask, saved channel or Quick Mask targeted.
  - Levels or Curves adjustment layer, Properties eyedropper armed (`layerPicker` in `ui.inspect`: `{layer, point, tool}`, set by the panel's Set Black/Neutral Gray/White Point buttons): a `down` sets that point from the image below the layer as one `layer.setAdjustment {"layer", "eyedropper": {"point", "at": [x, y], "size"}}` (send that command directly to skip the UI) and the tool is not driven; Esc, another tool or another layer disarms it.
  - Image › Adjustments › Levels/Curves on a raster mask, saved alpha/spot channel or Quick Mask uses grayscale controls in every document colour mode. Both dialogs list only the isolated target by its actual name (custom alpha/spot and mask names stay literal), with the matching channel controls and histogram; Levels Auto uses that histogram too. Black/White Point samples that plane's own values, including unstored defaults, with the Eyedropper's Sample Size clipped at the canvas edge; Neutral Gray is unavailable. Direct commands accept `{"target":"mask"|"quickMask"|{"channel":index}, "eyedropper":{"point":"black|white","at":[x,y],"size":1|3|5|11|31|51|101}}`. Sampling updates dialog parameters until OK; Cancel keeps the pixels. An Action step's explicit target takes precedence over the currently selected channel when choosing its dialog defaults, Levels/Curves channel name, histogram and preview. Its explicit `layer` selector also supplies the mask name, histogram, picker surface, preview and commit receiver without changing the selected layer. Missing or malformed tone targets show an unavailable message instead of colour controls or a colour histogram; repairing an address with `ui.dialog.set` re-seeds its recorded settings. Modal adjustment Action parameters must be an object or null; other shapes fail the step before opening a dialog. Reset, pencil editing and sampling retain that explicit target. Retargeting an armed picker through `ui.dialog.set` refreshes its sampling address, including removed address fields, while retaining its adjustment baseline. Scalar targets discard RGB/CMYK/Lab component records from recorded parameters. On scalar planes and native colour sets, a recorded `gray` alias seeds the visible combined controls so subsequent edits remain effective. Whole-image Curves Actions and Smart Filters also normalize that alias before seeding identity points. Unresolved targets retain their original alias until their address is repaired. Colour sets retain their native component records, including Lab's separate combined and Lightness settings; pencil conversion and smoothing are resolved once before dialog defaults are added. Null Lab records behave like omitted records. Opening and recalling Levels/Curves preserves accepted parameter precision, and scalar-plane sampling retains native precision. Colour-picker point rounding and pencil-map canonical precision are unchanged. Malformed aliases remain preview/commit errors. Adjustment-layer Properties keep sampling the colour image below the layer. Reopening an existing whole-image Smart Filter keeps its recorded colour controls regardless of the current channel or mask target. Captured Levels/Curves filter targets are validated before drawing controls, reading a histogram or sampling; a document switch shows an unavailable state until the original target is active again. Levels/Curves reject implicit vector-mask targets because vector masks use path editing; an explicit pixel target remains supported.
  - With a painting tool, Shift+right-click (without Alt, Ctrl or Command) opens that tool's menu, as in the reference application, even when right-click painting is set to Erase: Edit Brush… (opens the Brush Preset picker at the click) and then the tool's own Mode list from its options bar. Brush and Pencil: Edit Brush…, the painting modes with Behind and Clear; Clone Stamp, Pattern Stamp, History Brush: Edit Brush…, the blend modes; Mixer Brush, Color Replacement, Background Eraser, Blur, Sharpen, Smudge: Edit Brush… only; Eraser: Brush / Pencil / Block; Dodge and Burn: Edit Brush…, Shadows / Midtones / Highlights; Sponge: Edit Brush…, Desaturate / Saturate; Healing Brush: its blend modes; Gradient: the blend modes; Paint Bucket: the blend modes with Clear. Other tools (Spot Healing Brush, Magic Eraser, non-painting tools) keep their plain right-click route. `ui.inspect.brushModeMenu` reports its screen position, `tool`, current `mode` (the checked row's label), `choices` (the row labels, in order) and `items` (`{label, enabled, checked}` or `{separator: true}`); Behind and Clear are disabled on the Background layer. Pick a row with `ui.click`, or with `ui.context.choose {id}` where `id` is the row's English label from `choices` (an unknown or disabled row is an error that changes nothing). A row sets what the tool's options-bar control sets: a brush-based tool's blend mode goes through `tools.setBrush`; the Eraser, Range, Sponge, Gradient and Paint Bucket rows set the tool option. Clear has the same painting-only erase meaning as the options bar. Escape, an outside press or a tool change closes the menu without changing the brush or document.
- `ui.click {x, y, button?, count?}` / `ui.move {x, y}`: synthetic pointer input in screen points (`button`: `left` (default), `right` (or `secondary`) or `middle`). `count` (default 1, `2` for a double-click) is at most 256; a larger one is an error and queues nothing. `x` and `y` lie within ±1,000,000 points (off-window is fine); a larger magnitude is an error naming the field

- `ui.key {key, command?, shift?, alt?, ctrl?}` (flags may also be grouped under `modifiers`): press and release a key, e.g. `{"key": "ArrowLeft", "shift": true}`. `{"key": "AltLeft"}` is a tap on Alt, which puts the keyboard on the in-window menu bar (then `ArrowRight`, `ArrowDown`, `Enter`, `Escape` or a menu's letter drive it); `{"key": "F", "alt": true}` opens the menu with that mnemonic (#4988)
- `ui.pointer`, `ui.click`, `ui.move`, `ui.key` and `ui.screenshot` validate every parameter before acting, as `ui.set` does: an unknown field (top-level, under `modifiers` or in an event), a value of the wrong JSON type (`"x": "abc"`, `"ctrl": "yes"`), a `button`, `kind`, `tool` or `key` outside the accepted set, or a number outside its range (`pressure`, tilt, `rotation`, `count`, the `ui.click`/`ui.move` `x`/`y`) is an error naming the parameter, and nothing is queued or applied. A `null` field counts as omitted and takes its default
- Engine commands (`engine.execute`, `photocraft-cli run`, MCP `command_run`) reject a param key their `params` doc does not name for the commands listed in `STRICT` (`crates/engine/src/param_check.rs`, today `layer.hideLayers` and `layer.showLayers`): `{"ids":[4]}` is the error `unknown parameter \`ids\` (expected: layer)`, and nothing runs. Other commands still ignore unknown keys until their `params` doc is complete and they are added to that list (`coalesce` and `target` are always accepted).
- `ui.type {text}`: type text (goes to the focused widget, or to the canvas while the Type tool is editing)
- `ui.resize {width, height}`: resize the main window
- `ui.gpu.simulateLoss {error?}`: act as if the wgpu device was lost (or reported an error with `error: true`). The app switches to the CPU image compositor (after a loss for the rest of the session; after an error until a successful Retry GPU) and shows the same recovery warning as on a real loss. `gpuFallbackNotice` in `ui.inspect` contains the reason while the warning is open. Keep Using CPU saves CPU compatibility for the next launch. Retry GPU saves GPU mode; after an error (`error: true`) it also builds a new GPU canvas on the same device at once (`gpuInfo.canvas` is `gpu` again, #6577), and after a loss it asks the user to save and restart. The window renderer still requires a working graphics or software adapter. Returns `wasActive` and `gpuInfo`. For testing the fallback. With `destroy: true` it destroys the window's real wgpu device instead, as a driver reset does (see `docs/development.md` › device loss): the app saves every unsaved document for recovery and closes. Returns `destroyed`
- `ui.screenshot {path?, focus?}`: capture the main window (PNG). With no path the reply contains
  base64 PNG data; a path is relative to the automation write root. Raises the window first
  (default) because occluded macOS windows stop rendering. A request sent before the first frame
  is queued (within the same limits and deadline) and captures once the window geometry is known,
  as on 0.15. At most four captures may be outstanding (waiting for geometry, rendered or awaiting
  collection), one image may use at most 128 MiB and all of them at most 256 MiB; the budget is
  re-checked when the window changes before a queued request is captured, and an over-budget
  request is refused before it is captured. A request gives up after 8 s (including retries after
  a resize/DPI/zoom change), and a result that arrives after it was cancelled or timed out is
  discarded without a file or a second reply. Any size, scale, zoom, texture-side or minimized
  change between issuance and collection retries the capture even if the values change back, and
  a minimized window fails with an error instead of waiting for the timeout. The
  document (and its activation: a switch away and back) is fixed when the request is accepted: if
  another document becomes active before the capture, the request fails with an error rather than
  saving the wrong document
- `ui.focus`: bring the main window to the front
- `app.open {path}` / `app.save {path?, tgaBits?, ddsCompression?, ddsMipmaps?, quality?, jpegFormat?, tiffCompression?, tiffTransparency?, tiffPyramid?, tiffLayers?, maximizeCompatibility?}` (JPEG: `quality` on the 0–12 scale, `jpegFormat` `baseline`, `optimized` or `progressive`; TIFF: `tiffCompression` `none`, `lzw` or `zip`, `tiffTransparency` and `tiffPyramid` bools; automation never shows JPEG or TIFF Options; PSD/PSB: `maximizeCompatibility` false writes Photoshop's placeholder instead of the merged image (Bitmap, Indexed Color and Duotone documents still write the real image); unset or null follows Preferences › File Handling: Always and Ask When Saving write the real merged image, Never the placeholder, and `app.save` never opens a compatibility dialog): relative file I/O through the configured automation roots (`app.open` reads under the read root, `app.save` writes under the write root; absolute paths beneath the canonical or configured root are accepted, while `..` and paths escaping the root are refused, and both fail closed when no root was granted). Both reply with `warnings` (import/export notes such as "adjustment layer flattened"; `[]` when none), also shown to the user in the status bar and as a notice (`notices` in `ui.inspect`); `app.open` also returns the `path` and document `name` (directory `.pcraft` — the native on-disk form — loads through the read root's capability; the single-file (zip) form takes the bytes path), `app.save` the `path` written. `app.save` without `path` writes back only to the document's own PSD, PSB or `.pcraft` file, like File › Save. `tgaBits` (24 or 32) sets a TGA's bits per pixel: 32 writes the alpha channel (or else the transparency) as its alpha, 24 none; without it, 32 with an alpha channel or transparency, else 24. `ddsCompression` (`none`, `bc1`, `bc2` or `bc3`) and `ddsMipmaps` (bool) set a DDS texture's compression and mip chain; without them, uncompressed without mipmaps. Automation saves never show TGA, DDS, JPEG or TIFF options. Automation opens and saves never fire script events. Use these two rather than `file.open`, `file.save`, `file.saveAs` or `file.saveACopy`, which the control channel refuses (see [Engine commands](#engine-commands))
- `app.quit`

## Engine commands

Change the UI language without restarting with `prefs.set`:
`{"path":"interface.language","value":"fr"}`. Supported codes and preview/apply behaviour
are documented in [UI localisation](localization.md). `prefs.get` and the existing preference
store expose and persist the same setting; scripts keep using canonical command IDs.

`engine.execute` runs any command by id. `engine.commands` (or the engine command `command.list`) lists them all, with labels, menu paths, shortcuts, a parameter description, and whether each is currently enabled (reply shape: [Command list replies](#command-list-replies)). Each row carries `enabled` (bool), `disabledReason` (`null` when enabled, otherwise the precondition that failed, such as `"no document open"`, `"no selection"` or `"the clipboard is empty"`) and `needsDocument` (true when the command is off because no document is open, so the first step is to create or open one; a command may still have its own precondition after that, such as an active text layer. False when enabled or off for another reason). With no document open, nearly every document command reports `enabled: false, needsDocument: true`; plan around `needsDocument` rather than reading `enabled` alone (#3664). An unknown command id or method name fails with up to three near matches, for example ``unknown command `engine.commands`; did you mean `command.list`?``; a protocol method sent through `engine.execute`, or an engine command id sent as a method, says which of the two it is. Examples:

| Command | Params |
|---|---|
| `file.new` | `{"width":1920,"height":1080,"mode":"rgb","depth":8,"background":"white"}` |
| `layer.new.layer` | `{"name":"Ink"}` |
| `layer.select` | `{"layer":id\|str,"mode":"replace\|toggle\|range\|add\|remove"}` or `{"name":"Background","occurrence":0?}` (occurrence is zero-based document walk order; required for duplicate names): ⌘-click = toggle, ⇧-click = range; `document.inspect` reports `selectedLayers` and a per-layer `selected` flag |
| `channel.target` / `channel.setVisible` | Channels panel target and eyes (`"composite"`, colour name, alpha index or name, `"quickMask"`). `document.inspect` (and `channel.list`) report `channels`: composite/colour/alpha rows with visibility, channel options, `quickMask`, `target`. Pixel commands without a `target` param follow the targeted channel |
| `channel.options` | `{"channel":index\|name\|"quickMask"\|"mask",…}`: Channel Options (name, `indicates`, overlay `color`, `opacity`/`solidity`). On `"mask"` it is Layer Mask Display Options: the `color` and `opacity` of every layer mask's rubylith (`\`, ⇧⌥-click), kept in the preferences as `layerMaskOverlay` (not an undo step) and returned under that key |
| `layer.setProps` | `{"layer":id?,"name":…,"visible":…,"opacity":0..1,"blend":"Multiply"}` |
| `layer.fill.solidColor.set` | `{"layer":id?,"document":id?,"color":"#rrggbb"}`: edit a Solid Color Fill in one undo step; RGB without alpha preserves the fill's alpha. Float RGB arrays and a stored `Color` are also accepted. `document` rejects stale dialog targets. |
| `layer.fill.pattern.set` | `{"layer":id?,"document":id?,"pattern":id\|name?,"scale":1..1000?,"angle":-180..180?,"link":bool?,"phase":[x,y]?}`: edit a Pattern Fill (the Pattern Fill dialog's OK) in one undo step; omitted values keep the layer's, `phase` `[0,0]` is Snap to Origin. `layer.newFillLayer.pattern` from a menu (no params) and `layer.layerContentOptions` on a Pattern Fill layer open the Pattern Fill dialog. |
| `layer.layerMask.edit` | `{"layer":id?,"document":id?,"density":0..100?,"feather":0..1000?}`: edit pixel-mask Density (%) and Feather (px) without changing mask pixels, including adjustment masks. At least one setting is required; `document` rejects stale targets. A shared `coalesce` key groups slider updates into one undo step. |
| `layer.setExpanded` | `{"layer":id?,"expanded":bool?,"all":bool?}`: open/close a group in the Layers panel (no `expanded`: toggle; `all`: every group). A view change saved with the document (PSD open/closed folder), not an undo step; `document.inspect` reports `expanded` on groups |
| `layer.newAdjustmentLayer.hueSaturation` | `{"hue":30,"saturation":10}` |
| `paint.stroke` | `{"points":[[x,y,pressure],…],"size":20,"color":"#ff0000"}` |
| `select.rect` | `{"x":0,"y":0,"width":100,"height":50,"mode":"add","ellipse":false}` |
| `document.inspect` | `{}`: layer tree, history, snapshots (`[{id, name}]`, for `history.selectSnapshot`; id 0 is the document as opened, unless `history.options` `automaticallyCreateFirstSnapshot` is off; with `automaticallyCreateNewSnapshotWhenSaving` on, each save of a changed document adds one named `HH:MM:SS`, or `Snapshot N` in the browser; every snapshot keeps its copy of the document for the session: its tiles count against the History & Cache budget by dropping the oldest history states, but snapshots are never dropped themselves), selection bounds |
| `layer.list` | `{"document":index?,"flat":bool?}`: just the layers, top-down: `id`, `name`, `kind`, `visible`, `bounds` (`[x,y,w,h]` or null), `selected`, `active`; groups list their `children`, or with `flat` every layer is one row with its `depth` and `parent` group id |
| `document.pixel` | `{"x":10,"y":10}`: composite RGBA, four floats 0..1 (not 0..255) |
| `document.presets.list` | `{}` → `{presets:[{name,settings}]}`: saved New Document configurations |
| `document.presets.save` | `{"name":"Product square","settings":{"width":1600,"height":1600,"background":"transparent"}}`: save a snapshot; names are trimmed, 1–255 characters, and ASCII case-insensitive duplicates are rejected |
| `document.presets.get` | `{"name":"Product square"}` → `{preset,params}`: fetch settings; pass `params` to `file.new` to create a document, optionally adding a document `name` |
| `document.presets.delete` | `{"name":"Product square"}`: delete the named saved configuration |
| `document.recent.list` | `{}` → `{recent:[settings]}`: File › New › Recent, the settings of the documents last created with the New Document dialog, newest first (at most 20) |
| `document.recent.add` | `{"settings":{…as document.presets.save}}`: put settings first in Recent (the dialog does this after Create; equal entries collapse); not recorded into actions |
| `type.hitTest` | `{"layer":id?,"x":px,"y":px}`: character under a document point. No `layer` picks the topmost visible type layer there. Result `{"layer","index","line","inside"}` |
| `type.caret` | `{"layer":id?,"index":char}`: caret segment in document pixels, `{"index","line","segment":[[x,y],[x,y]]}` (rotated and vertical type included) |
| `type.navigate` | `{"layer":id?,"index":char,"move":"wordPrev\|wordNext\|linePrev\|lineNext\|lineStart\|lineEnd\|start\|end","x":px?}`: neighbouring caret. `x` keeps the column across line moves. Result `{"index"}` |
| `actions.list` | `{}` → `{actions:[{name, steps}], recording}` (the name being recorded, or null) |
| `actions.get` | `{"action": name or index}` → `{name, steps:[[id, params], …], disabled:[step, …]}`. `steps` is the shape `file.automate.batch` and droplets take; `disabled` lists the 0-based steps playback skips |
| `actions.record` | `{"name":"Red"}` starts a new action (default name `Action N`). `{"action": name or index}` appends to one that exists |
| `actions.stop` | `{}` → `{action, steps}`. Copies replayable journal entries since `actions.record` (queries and action-editing commands omitted). For portable playback, an active `layer` id is dropped only when it is the sole selected layer and does not supply source content (`layer.new.frame`, `select.loadSelection`, `type.createSelection`, `edit.checkSpelling`; a Check Spelling step keeps only `allLayers`, as the reference application's step does). Otherwise, including when several layers are selected, it is recorded by its unique name; `layer.select` records `{"name":"Layer","occurrence":0}`. Type tool keystrokes on a new layer fold into its `type.create` step; edits on an existing text layer retain separate replacements so styled text between edited spans survives replay. For commands other than `layer.select`, ambiguous layer names keep the id and require a unique name for portable playback |
| `actions.play` | `{"action": name or index, "from": step?}`. `from` and `failed.step` are 0-based. Returns `{action, ran, failed?:{step, id, error}}` and still returns ok when a step fails, so a partial run is reported. Leaves one history step per step that ran. Supports nested action calls up to 16 levels, rejecting cycles. While recording, playing another action appends one named `actions.play` step instead of its expanded commands. On an untrusted session each step is authorized the same way as a top-level command |
| `actions.move` | `{"action": name or index, "step": index?, "to": index}` moves a step within its action, or moves the whole action when `step` is omitted. `to` is the final zero-based index. Pending steps can be reordered while recording; invalid moves leave the list unchanged. |
| `actions.delete` | `{"action": name or index, "step": index?}`. With a zero-based `step`: `{action, deletedStep, steps}`, also allowed while recording. Without `step`: `{deleted}`, refused while recording |
| `actions.toggle` | `{"action": name or index, "step": index?, "enabled": bool?}` → `{action, disabled}`. Switches one 0-based step (pending recorded steps included) on or off; omitting `enabled` flips it. Without `step`, switches every step: on unless all already are. Playback, Batch and droplets skip steps that are off. In the desktop panel, click a step's check box |
| `actions.rename` | `{"action": name or index, "name": str}` → `{action, index}`. Empty, whitespace-only or duplicate names are rejected and keep the old name. Nested `actions.play` steps that call the action by name and its function key follow the new name. In the desktop panel, double-click an action's name to rename it in place (Enter commits, Esc cancels) |

The Actions list fills the resizable dock group.

Newly recorded Layers eye gestures resolve their targets by layer name and duplicate-name
ordinal during playback rather than retaining a document-local layer id. A missing target
reports a failed step instead of changing another layer.

The Actions panel shows replayable steps immediately while recording. Click an individual
step to select it, then use the trash button to remove that step; selecting the action
heading instead targets the whole action. Step deletion also works during recording
and does not undo the document edit. The control equivalent is
`actions.delete {"action": "Name", "step": 0}` (zero-based). Omitting `step` deletes
the whole action, which still requires recording to be stopped.
A step or action row dragged onto the trash is deleted without a confirmation, and one dragged onto the plus button is duplicated right after itself (`actions.duplicate`), as in Photoshop.

Desktop actions also record and replay View › Fit on Screen (`view.fitOnScreen`),
100% (`view.actualPixels`), Zoom In and Zoom Out through their menu commands or shortcuts.
Select an action and press Record to append steps; the plus button starts a new action.
A final `["view.fitOnScreen", {}]` step fits the resized document when the canvas is laid out.
Headless playback reports unsupported view commands as failed steps.

In the desktop Actions panel, right-click an action to assign a function key (F1–F12),
or choose None to remove it. The binding follows the action name, regardless of the selected
row, and is saved in preferences. For example, the existing `edit.keyboardShortcuts` command
accepts `{"set":{"actions.play:My action":"F6"},"allowUnknown":true,"removeConflicts":false}`.
A named action takes precedence over the ordinary menu shortcut while it exists and is bound;
removing its binding or deleting it restores that menu shortcut. The panel moves a key away
from another action when assigning it. Action playback still checks each nested command's
automation permissions.

UI-level commands (`view.zoomIn`, `window.theme.pro`, `edit.search`, …) are also accepted by `engine.execute` and `ui.menu.invoke`.

Commands that read or write files by path, instead of through the automation roots, are refused with "automation command `…` uses ambient filesystem paths and is disabled; use capability-scoped document methods". That covers every `file.*` command except `file.new`, the `file.close*` commands and a few path-free ones such as `file.fileInfo`, so `file.open`, `file.save`, `file.saveAs` and `file.saveACopy` always fail here: open and save with `app.open` / `app.save`. Path parameters of other commands (`layer.exportAs {path}`, `filter.distort.displace {mapPath}`, preset imports, and plug-in install/reload) are refused the same way. `prefs.set` rejects whole-preference updates and file-backed sections (`colorSettings`, `scriptEvents`, `historyLog`, `plugIns` and `scratchDisks`) so automation cannot configure ambient file access indirectly. The desktop app also refuses `image.mode.*`, which can load the colour profiles set in its preferences. The rules are in `crates/automation/src/workspace.rs`.

Embedded Smart Objects can be opened with `layer.smartObjects.editContents {layer?}` or
unpacked with `layer.smartObjects.convertToLayers {layer?}`. This includes Photoshop sources
stored by UUID in the document's embedded linked-layer blocks. Sources requiring a disk read
remain refused, including nested linked objects that need re-rendering during unpacking.
In the opened contents document, use `layer.smartObjects.saveContents {}` to update the parent
in memory, or close the dirty contents document. For nested objects, save from the deepest
contents outward. `app.save` exports the active document to a scoped file; it is not a substitute
for Save Contents. Save the parent document to disk when the edits are complete. These rules
also apply to recorded actions and synthetic UI input; interactive desktop commands retain
their usual file access. Source replacement, relinking and export commands remain restricted.

`type.editText` starts inline editing of the active type layer and selects all its text, like
double-clicking its thumbnail in Layers. Text input, Commit and Cancel use the existing Type tool
editing session; non-type layers return an error without changing the tool or document.

### Selected colour channel sets

`channel.target {"colors":[0,2]}` selects native colour components. Shift-click is
`channel.target {"channel":{"color":1},"extend":true}`: toggle that component,
starting from all colour components when the composite is selected. Masks and saved
channels cannot join a colour set. All components selected becomes the composite.
Channel inspection adds `selectedColors`; the legacy primary `target` remains.
Applicable drawing, adjustment, clipboard and filter commands follow the selected
set, or accept `"target":{"colors":[0,2]}` explicitly. Invalid or empty sets fail
without a document edit. Move/transform on partial sets and Camera Raw on a partial
set return an unsupported error. See [selected colour editing](multi-channel-editing.md).

### Command list replies

`engine.commands` (control channel and `serve`), the engine command `command.list` and the MCP
tool `command_list` all reply with a bare JSON array, not an object: there is no
`{"commands": [...]}` wrapper. On the control channel and `serve` the array is the reply's
`result` (`{"id":1,"ok":true,"result":[…]}`); the MCP tool returns it as its JSON text.
Each element describes one command, in registry order:

```json
{"id":"file.new","label":"New…","menu":["File"],"shortcut":"Cmd+N","params":"{\"width\":1..300000=1920,…}","enabled":true,"disabledReason":null,"needsDocument":false}
```

| Key | Type | Meaning |
|---|---|---|
| `id` | string | The id to pass to `engine.execute` / `command_run` |
| `label` | string | Menu label |
| `menu` | array of strings | Menu path above the item (`[]` for commands without a menu item) |
| `shortcut` | string or `null` | Default shortcut, e.g. `"Cmd+Shift+X"` |
| `params` | string | Human-readable parameter doc (not a JSON schema) |
| `enabled` | boolean | Whether the command can run in the current state |
| `disabledReason` | string or `null` | Why the command can't run now (`null` when `enabled`) |
| `needsDocument` | boolean | `true` when it is off because no document is open (#3664) |
| `keywords` | string, optional | Other names the command is found by (#5060), e.g. `select.rect`'s Elliptical Marquee; only present on commands that have them |

Filtering narrows the same array without changing its elements: `serve`'s `engine.commands
{filter}` and the MCP tool's `filter` keep commands whose id, label or keywords contain the text
(case-insensitive), and the MCP tool's `enabled_only` keeps those with `enabled: true`. The
desktop control channel's `engine.commands` takes no filter and always returns every command.
The shape is pinned by a test in `crates/automation/src/rpc.rs` (#3684).

### Background jobs (#210)

Long commands (every `filter.*`, `edit.contentAwareFill`, `edit.contentAwareScale`, `file.automate.photomerge`, `brush.presets.importAbr`), file opens, file places (`file.placeEmbedded` / `file.placeLinked`, File › Place and files dropped on the canvas: the file is read, decoded and resized on the worker, the layer is inserted when the job lands and Free Transform starts then) and interactive saves (File › Save, Save As and the TIFF Options continuation, #2017) run as background jobs in the desktop app: the window keeps drawing, the status bar shows progress with a Cancel button, and jobs that lock the active document show a modal progress dialog (Esc cancels; a place shows its progress in the status bar only, so the view stays free to pan and zoom). `engine.execute`, `ui.menu.invoke`, `ui.dialog.confirm` and `app.save` still wait for the result by default; pass `"wait": false` to get `{job, pending: true}` at once, then poll `jobs.list` (`state`: running, done, failed, cancelled; `progress` 0–1; the result or error) and stop it with `jobs.cancel {job}`. A cancelled or failed job leaves the document unchanged; a folder Batch can already have written earlier output files. A cancelled Batch has `state: "cancelled"` with its partial `result` in `jobs.list`; a waiting control request receives `{"ok":false,"error":"cancelled","result":…}`, and an MCP call through the app bridge gets the error `cancelled; partial result: {…}`. A Batch already asked to stop, or past its last input, is listed with `reason: "finishing"`. A save that has started replacing its file can no longer be cancelled: `jobs.cancel` leaves it running and lists it in `notCancelled: [{job, reason: "committing"}]` (next to `cancelled`, the number of jobs it did cancel); the save then ends as done or failed like any other. Closing its document doesn't stop it either. While a job runs, commands that would edit its document fail with "… is still running on this document". `ui.inspect` reports `jobs` (running jobs, opening files, saving files, the file being placed). Set `PHOTOCRAFT_INLINE_JOBS=1` to run everything inline. The web build has no threads: there a file place is the only job, and it runs a few milliseconds per frame on the UI thread (the same progress, cancel and result); every other command is inline.

## Preferences

Preferences (Edit › Preferences, grouped like Photoshop's dialog sections) live in the engine, so
the same commands work in the app, the CLI and headless MCP. Paths are dotted camelCase keys:
`<section>.<key>`, with sections `general`, `interface`, `workspace`, `tools`, `historyLog`,
`fileHandling`, `export`, `performance`, `scratchDisks`, `cursors`, `transparencyAndGamut`,
`unitsAndRulers`, `guidesGridAndSlices`, `plugIns`, `type`, `enhancedControls`, `rawDefaults`,
`integrations`, plus `shortcuts.<command id>`, `menus` (`hidden`, `colors.<id>`), `toolbar`
(`hidden`, `order`) and `colorSettings` (Edit › Color Settings).

| Command | Params |
|---|---|
| `prefs.get` | `{"path":"performance.historyStates"}`; no path returns everything |
| `prefs.set` | `{"path":"cursors.painting","value":"precise"}` or `{"values":{"unitsAndRulers.rulers":"cm","guidesGridAndSlices.gridColor":"#ff8800"}}`. Values are validated (choices, ranges, `#rrggbb` colours, shortcut syntax); a batch applies all or nothing. A section path takes an object and merges it key by key |
| `prefs.reset` | `{"path":"performance"}` (a section or key); no path resets everything. An individual `shortcuts.<id>` or `menus.colors.<id>` reset removes the override and returns `null`, including when it is already absent |
| `edit.preferences.<section>` | the section's values; in the app (no params) it opens the Preferences dialog on that section |
| `edit.keyboardShortcuts` | `{"set":{"edit.fill":"Cmd+Shift+F"},"reset":true\|["id",…],"removeConflicts":true,"filter":"blur","list":false,"importKys":"<.kys XML>"}`: returns overrides, matching commands and conflicts. A shortcut moved to another command is removed from its old owner unless `removeConflicts` is false. `""` removes a shortcut, `null` restores the default. The held temporary tools are bindable too: `tools.temporary.hand` (Space; also repositions a selection being drawn), `tools.temporary.zoomIn` (Cmd+Space), `tools.temporary.zoomOut` (Alt+Space; Alt added to a held Zoom In, Cmd+Alt+Space, zooms out too), `tools.temporary.erase` (`` ` ``; with the Brush or Pencil, a stroke started while it is held is in Clear mode, `paint.stroke`/`paint.pencil` `"mode": "clear"`, erasing with that tool's brush); they list with `"hold": true`. ⌘ (Ctrl off the Mac) held alone is the Move tool with the painting, retouching and other non-selection tools, as in Photoshop; it is a modifier, not a binding. `importKys` applies a Photoshop `.kys` set (the file's XML text, at most 4 MiB): rows are matched to commands by our id (`pc-id`, in sets PhotoCraft exported) or else by menu label, a key equal to the default restores it, keys also given in `set` win, and the result gains `import` (`name`, `imported`, `set`, `unknown`, `unreadable`, `alternates`, `toolKeys`, `windows`). A set saved by Photoshop on Windows (no ⌘ or Opt anywhere, Ctrl used) reads Ctrl as the primary modifier, so `Ctrl+L` is the `Cmd+L` default (`windows: true`). Tool keys are matched to tools by `pc-id` or name (a tool's own letter keeps its Shift cycling); `import.tools` lists the keys given. In the app it opens Keyboard Shortcuts and Menus, whose Import Shortcuts… button loads a `.kys` set into the dialog (opening or dropping a `.kys`, or Photoshop's live `Keyboard Shortcuts.psp`, does the same). On a desktop with Photoshop installed, the first launch that has no shortcut overrides yet asks whether to import the newest install's live set (Import / Don't Import; `ui.inspect` shows it as `kysOffer`); the answer is recorded in the preferences as `dialogs.photoshopShortcuts`, so it is asked once. **Sets** (Edit › Keyboard Shortcuts › Set): `useSet` loads a saved set's bindings (`""` or `"PhotoCraft Defaults"`: the defaults) before the call's other changes; then `saveSet` saves the bindings as they end up under a name and uses it, `deleteSet` removes one (the bindings stay), `sets` replaces every saved set (`{"<name>": {"shortcuts": {…}, "alternateShortcuts": {…}}}`, the dialog's OK) and `activeSet` names the set in use without loading it. Names are trimmed, 1–64 characters, at most 64 sets. Every reply has `sets`, `activeSet` (`""` for the defaults), `defaultsName` and `modified` (the bindings differ from the set in use). `exportKys: true` adds `kys`, the bindings of every bindable command and tool as a `.kys` file (Photoshop's macOS key spelling; each row carries our id as `pc-id`, so the file imports back exactly); `summarize: true` (or `{"mac": false}`) adds `html`, Photoshop's Summarize page. A bad parameter anywhere in the call, an export path that can't be written included, changes nothing. **Headless parity:** the shell's commands (View › Zoom In, the panels; `photocraft_engine::shell_commands::SHELL_COMMANDS`) and the tools (`tools.select.<tool>`, listed with `"tool": true`) are bindable, listed, imported, exported and checked for conflicts without the UI; tools may share a key (they cycle with Shift, so a shared letter is no conflict), while a command given a tool's key takes it from the tools. Keys the system takes first (Alt+Tab, Alt+F4, Ctrl+Alt+Delete everywhere but the Mac, plus Ctrl+Esc and Ctrl+Shift+Esc on Windows and Ctrl+Alt+F1–F12 on Linux; ⌘Tab, ⌘`, ⌘⌥Esc on the Mac) are refused, and left out of an imported set (`import.reserved`). Files: `importKys: {"path": …}` reads a `.kys`, `exportKys: {"path": …}` and `summarize: {"path": …}` write the file (the reply has `kysPath` / `htmlPath`); automation (MCP) refuses these paths, as it does `actions.save`'s |
| `edit.menus` / `edit.toolbar` | `{"hide":["edit.fade"],"show":[…],"color":{"edit.fill":"red"},"reset":false}` / `{"hidden":["Sponge"],"order":[…]}` |
| `edit.colorSettings` | `{"workingRgb":"display-p3","workingCmyk":"coated-cmyk","workingGray":"sgray","policyRgb":"preserve\|convert\|off",…,"askOnMismatch":true,"intent":"perceptual","bpc":true}`; honoured when opening files (`file.openAs`, the app's File › Open) and by Image › Mode and "working" profile specs. `color.profileMismatch {"action":"preserve\|convert\|discard\|assignWorking"}` answers the mismatch prompt |

Values the app honours live: history states (every open document), effect-cache budget, interface
theme, canvas colour and border, checkerboard size and colours (CPU and GPU canvas), gamut warning
colour and opacity, guide/grid/smart-guide colours and styles, grid spacing and subdivisions, ruler
units (rulers, Info panel, Image Size default unit), image interpolation (Image Size default),
painting and other cursors, zoom with scroll wheel, Use Shift Key for Tool Switch, Bundle Arrow-Key
Nudges and Nudge Bundle Pause (arrow keys sent with `ui.key` that follow each other within the pause
nudge the layers, selection outline or Free Transform box as one history step; an agent calling
`layer.translate` or `select.transformSelection` itself gets the same with a shared `coalesce` key),
keyboard shortcuts, hidden and coloured menu items, autosave interval and crash recovery, and the history
log text file. GPU on/off and the GPU tile size apply at the next launch.

The desktop app stores them in `preferences.json` in the platform config directory (macOS
`~/Library/Application Support/Photocraft`, Windows `%APPDATA%\Photocraft`, Linux
`$XDG_CONFIG_HOME/photocraft`; override with `PHOTOCRAFT_CONFIG_DIR`); autosaves go to its
`Recovery` folder (on Windows to `%LOCALAPPDATA%\Photocraft\Recovery`, out of the roaming
profile, and on Linux to `$XDG_STATE_HOME/photocraft/Recovery`, by default
`~/.local/state/photocraft/Recovery`, out of the config folder; autosaves left by earlier
versions move there at startup), and the window size and
position, the dock width and floating-panel geometry
to `ui.ron` beside it (a file holding values that would crash startup is discarded). In portable mode (a `portable.txt` or `PhotoCraft.portable` file beside the
executable, as in the Windows portable zip) that directory is `PhotoCraftData` next to the
executable instead. The web build keeps them in `localStorage`. A save writes only the values
this instance changed since it last loaded or saved them over what storage holds now, so a second
browser tab (or app window) never reverts the other's changes; for a value changed in both, the
latest save wins. A failed write stays pending and is retried (after 2 s, doubling up to 30 s, and
sooner after a further change); the status bar reports the first failure and a notice a
persistent one.

User and imported (`.abr`) brush presets live in the config directory's `Presets` folder: one
`.pcbrushes` JSON file per preset group, content-addressed tip bitmaps under `tips/`, and an
`index.json` with the group order and deleted built-ins (see `photocraft_engine::preset_store`).
The store loads in the background at launch and syncs after every brush preset change; built-ins
are never written. The Actions list is `actions.json` in that same folder and survives a restart.
Headless CLI/MCP sessions and the web build keep brush presets and the action list for the session
only, unless a store is attached. Gradient presets (including imported `.grd` groups) persist with
the preferences.

`brush.presets.importAbr` and `gradient.presets.importGrd` never overwrite a group by default: a
file whose group name is already taken imports beside it as `<group> (2)`, `<group> (3)`…, and the
result's `group` names the one it landed in. Pass `"replace": true` to delete that group's own
presets first (built-in brushes are kept); the preset libraries are outside document history, so
this can't be undone (#10640). In the app, opening such a file (`app.open`, File › Open,
drag-and-drop, Import Brushes…) shows a prompt instead: `ui.dialog.confirm` imports as a new
group, `ui.dialog.set {"choice":"replace"}` then `ui.dialog.confirm` replaces, and
`ui.dialog.cancel` imports nothing.

Named New Document presets also persist with preferences (`presets.documents`) on desktop and
web. File › New › Save Preset… saves the current form; the Saved tab selects a configuration or
deletes it. Selection only fills the form: Create still runs `file.new`, and the document name
is independent of the preset name. Settings include pixel width/height, resolution in ppi,
mode, depth, background, and display `unit` (`px`, `in`, `cm`, `mm`, `pt`, `pica`) and
`resolutionUnit` (`in`, `cm`). The defaults match File › New. Background Color captures the
toolbox colour as `backgroundColor: [r,g,b]` (0..1), so reusing it does not follow later toolbox
changes. Up to 256 presets are kept. Invalid saved entries are skipped independently; other
presets and preferences still load. Automatic Recent configurations are separate follow-up work.

## Update checks

On desktop, `engine.execute` with `help.checkForUpdates` and `{}` starts a background
check; `updates.status` returns `{supported, currentVersion, result}`. The result's `status`
is `idle`, `checking`, `upToDate`, `available` (with `release: {version, url}`), or `failed`
(with `message`). No document is required and neither command adds history or journal entries.
Headless and web sessions without a release transport report `supported: false`.

Set `general.automaticallyCheckUpdates` with `prefs.set` to enable or disable the next
desktop startup's single check (enabled by default). Manual checks still work when automatic checks are off.
`ui.inspect` includes `updates` and `updatesOpen`; `ui.set {"updatesOpen": false}` closes
the non-modal update window.

## Snapping

With View › Snap on, tool gestures snap to the View › Snap To targets (guides and grid while they
are shown, layer edges and centres, document bounds and centre, selection edges) within 8 screen
pixels: Move tool drags (the moved layers' bounds), marquee, crop, shape, type-box and pen points,
Free Transform handles and drags inside the box, and guides. Distort corners snap to enabled
guides and their intersections, using the actual corner even when its handle is grabbed off-centre.
Guide targets are excluded when Guides, Canvas Guides or Extras is hidden, for all snapping gestures.
Ctrl/Cmd corner distortion in Free Transform does the same with its enabled snap targets. Holding
Ctrl disables snapping for other gestures; Ctrl used for an allowed corner distortion keeps snapping.
With View › Show › Smart Guides on, the Move tool also snaps to other layers and draws
magenta alignment lines. `ui.pointer` drives the same code, so agents get identical results.

## MCP bridge

`photocraft-automation` provides an MCP server built on the official Rust SDK (`rmcp`). It runs in one of two modes:

- **Headless** (`photocraft-cli mcp`): an in-process `photocraft_engine::Session`. There is no window. CPU composition is the default; `--gpu` or `PHOTOCRAFT_GPU=1` enables optional GPU rendering with automatic CPU fallback.
- **Bridge** (`photocraft-cli mcp --bridge 127.0.0.1:7878 --control-token-file <path>`): every tool is forwarded to a running `photocraft --control 7878 --control-token-file <path>` over this protocol, so agents see and drive the live app. Explicit `--gpu` / `--no-gpu` flags are rejected with a usage error because the desktop controls rendering; `PHOTOCRAFT_GPU` is ignored in bridge mode. `--bridge 7878` is short for `--bridge 127.0.0.1:7878`. With no `--bridge`, `PHOTOCRAFT_CONTROL_PORT` selects the bridge port (`127.0.0.1:<port>`), and the CLI says so on standard error; with neither (or the variable empty), the MCP runs headless. A value that is not a port is a usage error naming the variable. `--automation-read-root` or `--automation-write-root` with the variable set is a usage error, since the bridge would drop the roots.

The bridge keeps one authenticated TCP connection open, and drops and reconnects before a call once the connection has been idle long enough that the app (which closes idle connections after 30s) may have dropped it. A transport failure while sending a request or waiting for its reply, including a reply timeout, drops the connection and reports that the operation may have completed (a call abandoned before its reply, such as a cancelled MCP wait, also drops it, so the next call never queues behind it); inspect the document before retrying an edit. Edits are never automatically resent (#1007); a connection that could not be established is reported as "the request was not sent" instead. The MCP server opts its pure-read tools (`ui_inspect`, `doc_inspect`, `command_list`, `jobs_list`, `session_list`, `ui_screenshot`) into one automatic retry on a fresh connection, since a read applies nothing; clients driving `BridgeClient` directly opt in per call with `call_read`. The next separate call reconnects and authenticates, and reply lines whose `id` does not match the request are skipped. The client's call timeout is 55s, strictly below the server's 60s reply deadline, so the bridge's error is the one callers see. A waited MCP `command_run` (or `command_batch` step) of an engine command is not bound by it (#8130): the bridge sends `engine.execute` once with `"wait": false` and, when the app starts a background job, polls `jobs.list` until the job ends and returns its result, forwarding progress and cancelling the job (`jobs.cancel`) when the request is cancelled, at once, even while a poll still waits on the app. Limits: a command that does not run as a job, a UI command (not an engine command; the app waits on it) and a lost reply to the start itself still fail at the timeout, the last with "operation may have completed" (look for the job in `jobs_list` before retrying); a failed poll of an uncancelled wait reports the job id and leaves the job running; and an unresponsive app still times out. Clients driving `BridgeClient` directly pass `"wait": false` and poll `jobs.list` themselves. It only accepts the literal loopback addresses `127.0.0.1:<port>` and `[::1]:<port>`, because the app only listens on loopback; `localhost:<port>` means `127.0.0.1:<port>` and is never looked up, since a lookup may return `[::1]` first and reach another process listening there. Every connection authenticates by challenge (see above), so the token is never sent, and a listener that cannot prove it holds the token is reported as such ("the control token was not sent"); an app too old for challenge authentication is refused the same way, so update the app with the CLI. Supply its bearer token with `--control-token-file`, `--control-token`, `PHOTOCRAFT_CONTROL_TOKEN_FILE`, or `PHOTOCRAFT_CONTROL_TOKEN`:

```sh
photocraft-cli mcp --bridge 127.0.0.1:7878 \
  --control-token-file /private/path/photocraft-control.token
```

How each MCP tool maps onto control methods in bridge mode:

| MCP tool | Control method |
|---|---|
| `command_run {id, params, wait?}` | `engine.execute {command: id, params, wait: false}`; when `wait` is true (the default), then `jobs.list` until a started job ends (`jobs.cancel` on cancellation), and with `wait: false` the `{job, pending}` reply is returned as is. A UI command id is sent with `wait` as given |
| `jobs_list` / `jobs_cancel {job?}` | `jobs.list` / `jobs.cancel {job?}` |
| `command_list {filter?, enabled_only?}` | `engine.commands` (filtered by the MCP server; replies with the same bare array, rows keep `disabledReason` and `needsDocument`, see [Command list replies](#command-list-replies)) |
| `doc_new {…}` | `engine.execute {command: "file.new", params}` |
| `doc_inspect` | `engine.execute {command: "document.inspect"}` |
| `doc_open {path}` | `app.open {path}` |
| `doc_place {path, …}` | `engine.execute {command: "file.placeEmbedded", params}` |
| `doc_replace_smart_object {path, layer?, …}` | `engine.execute {command: "layer.smartObjects.replaceContents", params}`, which the desktop refuses (the command reads an ambient path, and no control method reads it through the automation root yet; `doc_place` is refused the same way). An `index` is refused in bridge mode instead of being dropped, since the command runs on the app's active document. Use it headless or in the workspace server (`doc.replaceSmartObject`), where `path` resolves beneath the read root |
| `doc_export_layers {dir, …}` | `engine.execute {command: "file.export.layersToFiles", params}` |
| `doc_export_data_sets {dir, …}` | `engine.execute {command: "file.export.dataSetsAsFiles", params}` |
| `doc_import_data_sets {path, …}` | `engine.execute {command: "file.import.variableDataSets", params}` |
| `doc_save {path?, tgaBits?, ddsCompression?, ddsMipmaps?, maximizeCompatibility?}` / `doc_export {path, tgaBits?, ddsCompression?, ddsMipmaps?, maximizeCompatibility?}` | `app.save {path?, tgaBits?, ddsCompression?, ddsMipmaps?, maximizeCompatibility?}` |
| `doc_render_preview {max_side?}` | `ui.screenshot`, returned directly as PNG image content |
| `session_list`, `ui_inspect` | `ui.inspect` |
| `ui_screenshot {max_side?}` | `ui.screenshot`, returned as PNG image content |
| `ui_pointer {events, modifiers?, button?}` | `ui.pointer` (other arguments are an error) |
| `ui_menu_invoke {id}` | `ui.menu.invoke` |
| `ui_set {fields}` | `ui.set` |
| `control_call {method, params}` | any method, passed through unchanged |

Bridge previews capture the app window; passing `index` is an error. Headless `doc_render_preview` supports `index` without changing the active document.

`doc_select` and `doc_close` work only in headless mode. The `ui_*` tools and `control_call` work only in bridge mode; in headless mode they return a tool error that explains how to start bridge mode.

**Security note:** TCP control uses a bearer token, not client identity or general per-method
authorization. A client that possesses the token receives the non-filesystem control surface,
including UI input, command execution, and application control. Keep token files private, do not
commit or log tokens, and do not pass a token directly on a shared system where process command
lines are visible. The protocol is unencrypted and must remain on loopback; do not tunnel or proxy
it to an untrusted host.

Filesystem access fails closed unless launch-time read and/or write roots are granted with
`--automation-read-root` and `--automation-write-root`. Repeat the read flag to grant an ordered
list of directories; both `--flag <dir>` and `--flag=<dir>` syntax are supported by desktop,
headless MCP and `serve`, and duplicate read roots are allowed. Headless reads try those roots
in launch order and select the first existing regular file. Only a missing file (`NotFound`)
falls through; directory, permission, path-escape and decoding errors are terminal.
Desktop `app.open` also accepts native directory `.pcraft` documents through the selected read
capability. It searches in the same order: a ZIP file in an earlier root wins over a directory
in a later root. Once a directory is selected, loading errors are terminal. Directory opens
never establish an implicit save target, even when the read and write capabilities match;
use an explicit layered Save As beneath the write root.
Every configured root must be an existing directory. An empty, missing or invalid root fails
startup rather than being dropped. There is exactly one optional write root; repeated
`--automation-write-root` flags are usage errors (exit 2), even when the values match.

The desktop `PHOTOCRAFT_AUTOMATION_READ_ROOT` environment variable supplies a single fallback
directory, not a path list. Any explicit read-root flags replace it, preserving CLI order.
One explicit write-root flag overrides `PHOTOCRAFT_AUTOMATION_WRITE_ROOT`. These environment
variables are not supported by headless `photocraft-cli mcp` or `serve`; supply flags explicitly.
In MCP bridge mode, configure roots on the desktop process. Supplying root flags to
`photocraft-cli mcp --bridge` is a usage error; a bridge client cannot grant filesystem access.

Request paths must be non-empty, forward-slash relative paths beneath the applicable root, or
absolute paths beneath a corresponding granted root. An absolute path is compared with the
configured roots as text and the remainder is checked like a relative path. The file is opened
through the held directory capability, without ambient filesystem canonicalization of the
request. Absolute paths outside all corresponding roots, parent traversal, alternate separators
in relative paths, drive/device/stream prefixes, malformed components, and link escapes are
rejected before file effects. Read and write authority are independent: a write root never
grants reads, and writes do not search read roots. The parent of a new output file must already
exist.

An automation-opened document retains an implicit save target only when its winning read root
and configured write root use the same held directory capability. Differently configured aliases
and nested roots conservatively require explicit Save As, even if they name the same underlying
file. An explicit successful layered save beneath the write root establishes its save target;
a flat export does not. Existing PSD/PSB/`.pcraft` restrictions on pathless saves still apply.
This automation safeguard leaves interactive file-picker access unchanged. Desktop document
identity for Cmd+S and Open Recent is a separate concern.

Engine commands that still use ambient filesystem paths are disabled for automation until they
are migrated to the same capability interface. Extra read roots do not enable ambient asset reads
or headless directory-bundle access. Desktop `app.open` supports directory `.pcraft` only through
its granted read capabilities. Interactive desktop file pickers retain normal user-selected access.

## Headless server

An unused TCP headless server exits after 30 minutes without a client connection, releasing
its listening port so a later session can reuse it (#3682). An active connection prevents
idle shutdown, including during a long command. Clients should reconnect by restarting
`photocraft-cli serve` if they need a server after the idle deadline.

`photocraft-cli serve` keeps one headless engine session (no window; CPU by default, optional GPU acceleration via `--gpu` or `PHOTOCRAFT_GPU=1`) and answers the same
JSON-lines envelope on stdio, or on `127.0.0.1:<port>` with `--port <port>` or, without the flag,
`PHOTOCRAFT_CONTROL_PORT` (loopback only; each
authenticated connection shares the session). TCP uses the same first-frame `auth` exchange and
token options as desktop control. Stdio does not require this TCP handshake because access is
inherited from the process pipe. It is the fastest way for a script or agent to make many edits:
no MCP framing, no app start-up per command. Configure its file access with the same
`--automation-read-root` and `--automation-write-root` flags. When the
variable, not the flag, turns on TCP, `serve` says so on standard error; an empty value keeps
stdio, and a value that is not a port is a usage error naming the variable. Implementation:
`crates/automation/src/rpc.rs`.

| Method | Params |
|---|---|
| `engine.execute` | `{command, params?, wait?}`: any engine command (`wait: false` starts a long one as a background job: `{job, pending}`) |
| `jobs.list` / `jobs.cancel` | `{}` / `{job?}`: background jobs; cancel one or all (`{cancelled: n}`, plus `notCancelled: [{job, reason}]` for jobs left running, e.g. a save already writing its file). Every request (and MCP tool call) first applies the jobs that finished, so `doc.save`, `doc.inspect`, `doc.render` and `session.list` include a finished job's result without polling `jobs.list` first |
| `engine.commands` | `{filter?}`: registry with params docs and enablement (`enabled`, `disabledReason`, `needsDocument`); `result` is a bare array of command objects ([Command list replies](#command-list-replies)) |
| `session.list` | open documents and the active index |
| `doc.open` / `doc.new` | `{path, approveHighMemory? (false)}` / `file.new` params (`approveHighMemory` is the same one-shot PSD/PSB consent as the `file.openAs` command; see [development.md](development.md) for the structured refusal fields) |
| `doc.place` | `{path, scale? (percent), fit? (true), center? ([x, y]), approveHighMemory? (false), index?}`: places a file as a Smart Object layer above the active one and returns `{layer, scale, bounds}`. `path` resolves beneath the read root, so this is the capability-scoped `file.placeEmbedded` — that command itself still refuses an ambient path. `approveHighMemory` is refused unless it is a boolean |
| `doc.replaceSmartObject` | `{path, layer? (id or name; default the active layer), index?}` → the command's `{layer, instances}`: replaces a Smart Object's contents (one history step, transform and filters kept). `path` resolves beneath the read root, so this is the capability-scoped `layer.smartObjects.replaceContents`, which itself still refuses an ambient path (#8061) |
| `doc.exportLayers` | `{dir, format? (png), prefix?, visibleOnly? (true), quality?, index?}` → `{files, skipped}` (plus `count` for workspace exports): one file per exported top-level layer, named like `file.export.layersToFiles` names them. `count` is present only for workspace exports and counts written files only. `skipped` is always an array (empty when nothing is omitted), in top-to-bottom order, of `{layer, name, reason}`: the session layer id, original unsanitized name, and `"hidden by visibleOnly"` or `"adjustment layer has no pixels of its own"`. Visibility takes precedence for hidden adjustments; `visibleOnly:false` exports hidden non-adjustment layers. Groups export merged; their children are not separate exports or skips. Existing filenames/numbering are unchanged. `dir` resolves beneath the write root, so the ambient command stays refused. The bytes come from the command's own core, so both paths write the same files; the write capability refuses to overwrite an existing file. Encode/write failures are errors, not skips |
| `doc.exportDataSets` | `{dir, format? (png), dataSets? (all), naming? ("{name}\|{index}\|{document}"), index?}` → `{files, count}`: the capability-scoped `file.export.dataSetsAsFiles`. The batch is planned first and colliding names are refused before any file is written, as in the command |
| `doc.importDataSets` | `{path, delimiter? (,), index?}` → `{imported}`: the capability-scoped `file.import.variableDataSets`; the CSV is read beneath the read root |
| `doc.save` | `{path?, format?, quality?, index?, tiffLayers?, tiffCompression?, tiffTransparency?, tiffPyramid?, tgaBits?, ddsCompression?, ddsMipmaps?, pdfSpotPlates?, pcraftFullComposite?, maximizeCompatibility?}` (`.pcraft` native, else export by extension; set `tiffLayers: true` to preserve TIFF layers rather than exporting a flattened TIFF; `tiffCompression` (`none`, `lzw`, `zip`), `tiffTransparency` (bool: Save Transparency; unset, kept unless the document has alpha or spot channels) and `tiffPyramid` (bool) are TIFF Options; `tgaBits` 24 or 32 sets a TGA's bits per pixel, `ddsCompression`/`ddsMipmaps` a DDS texture's compression and mip chain, and `maximizeCompatibility: false` writes a layered PSD/PSB with Photoshop's placeholder instead of the merged image, except for Bitmap, Indexed Color and Duotone documents, as `app.save` does; `pdfSpotPlates: false` leaves a PDF's spot plates out, which are written by default, and refuses a Multichannel document, which has no image to write without them; `pcraftFullComposite: true` also writes the flattened document at its canvas size into a `.pcraft` file as `composite/full.png`; the save may leave it out in the cases listed in [the format guide](../book/src/formats/pcraft.md), and the manifest's `full_composite` member names it when written). Without `path` only a PSD, PSB or `.pcraft` document is written back to its own file, in its own format; anything else is an error and the file is left unchanged. A successful layered save (PSD, PSB or `.pcraft`) records the current revision as saved and makes the file the document's path, so `session.list` reports `dirty: false`; a flat export is a copy and leaves the document dirty |
| `doc.inspect` | `{index?}`: same JSON as `document.inspect` |
| `doc.render` | `{index?, maxSide? (1024; 0 = full), path?}`: PNG to `path`, else `{mime, base64}` |
| `doc.select` / `doc.close` | `{index}` / `{index?}` |
| `batch` | `{steps: [{command, params?, wait?} \| {method, params?}], stopOnError? (true)}` → `{completed, failed, results}` (a step with `wait: false` starts a long command as a background job, like `engine.execute`) |
| `methods` | the list above |

An `index` targets that one call: `doc.place`, `doc.exportLayers`, `doc.exportDataSets`,
`doc.importDataSets`, `doc.save`, `doc.inspect` and `doc.render` act on the document at `index`
without making it the active one, so the next call without `index` still runs on the document
that was active before (`doc.select` is the method that changes it).

```sh
printf '%s\n' \
  '{"id":1,"method":"doc.open","params":{"path":"in.jpg"}}' \
  '{"id":2,"method":"batch","params":{"steps":[{"command":"image.adjustments.invert"},{"command":"filter.blur.gaussianBlur","params":{"radius":3}}]}}' \
  '{"id":3,"method":"doc.save","params":{"path":"out.png"}}' | \
  photocraft-cli serve --automation-read-root /work/project --automation-write-root /work/project
```

The MCP server has the same batching as the `command_batch` tool (`{steps:[{id, params, wait?}], stop_on_error}`),
in headless and bridge mode. A step with `wait: false` returns `{job, pending}` at once, as `command_run`
does; later steps that edit the same document fail with a message naming the job until it ends.

## Transport limits

The desktop and headless TCP listeners currently enforce:

- a 1 MiB maximum encoded request line;
- an 8 MiB maximum encoded JSON reply, including the newline;
- at most 16 simultaneously serviced connections per listener;
- a 30-second socket read/write timeout;
- at most 256 steps in a headless `batch` or MCP `command_batch` request.

An oversized line, excess connection, unauthenticated request, or unauthorized filesystem path is
rejected before command dispatch or file effects. The headless JSON-lines stdio server also
enforces the request and reply byte ceilings; MCP over stdio (`photocraft-cli mcp`) does not
cap request bytes, because the MCP SDK reads its own request lines (only MCP tool results are
checked). A TCP connection is closed after an oversized
line; on stdio an oversized or non-UTF-8 line gets one error reply (`id: null`), the rest of that
line is skipped without being dispatched, and the session and its open documents keep serving. MCP tool results are checked as encoded JSON,
including the text/image content envelope, and the MCP bridge bounds incoming desktop replies.
A `batch` or `command_batch` stops at the first step whose result no longer fits the reply budget
(that step may have run; later ones do not). MCP charges each result at its size escaped inside
the text content, so the reply still lists `completed`, `failed` and every result so far, ending
with the budget error.

Headless automation previews (`doc.render` / MCP `doc_render_preview`) allow a maximum requested
edge of 2048 pixels and a source document of at most 67,108,864 pixels. `maxSide: 0` (MCP
`max_side: 0`) still means full size, but fails if the document's longest edge exceeds 2048.
PNG results are capped at 5 MiB before base64 encoding or writing a rendered file. Preview
dimension/source checks run before compositing; the encoded-PNG check runs after encoding.
Explicit trusted-local CLI rendering keeps its existing behavior.

Batch replies have an aggregate byte budget with space reserved for the outer reply and ID.
Exhausting it stops later steps even when `stopOnError` is false. A result can exceed the reply
budget after an edit has run: the error says the operation may have completed. Earlier steps
are not rolled back; inspect state before retrying. The MCP bridge drops an oversized incoming
reply without automatically retrying the operation. Bridged screenshots are decoded with
8192-pixel edge, 16,777,216-pixel, and 64 MiB allocation ceilings, even without downscaling.

These ceilings do not implement explicit JSON-depth policy, total session/document-memory
accounting, compositor scratch-space accounting, command cancellation/duration limits, or
general per-method capabilities. Desktop screenshot capture/encoding and document import/export
still need their own operation budgets; the desktop reply ceiling applies after the UI creates
its response. A bounded output does not imply bounded command cost.

### Rendering modes

`performance.renderingMode` accepts `auto`, `gpu`, or `cpu`. Automatic is the default for new
settings; older `useGpu: false` or `gpuBackend: cpu` preferences continue to select CPU mode
until an explicit mode is saved. Changes apply at the next launch. Automatic and GPU both
fall back on graphics errors rather than risk documents. CPU compatibility composites images
on the CPU and prefers software window adapters, when available. macOS still uses Metal for
the window. A failed window renderer initialization retries once in CPU compatibility mode;
a driver process crash is detected by the startup marker on the next launch.

### Camera Raw dialog

On the desktop the dialog is a window of its own (title bar, moved and resized like any window), as Adobe Camera Raw is; the main window is dimmed and takes no input while it is open, and closing the window is Cancel. Where the platform has no extra windows (the web build) it is drawn over the main window.

**Screenshots:** `ui.screenshot` captures the main window only, and eframe cannot capture an
immediate viewport, so while Camera Raw has its own window the PNG shows the dimmed main window,
not the dialog. Read the dialog's state through `ui.inspect` (`cameraRaw`: params, histogram,
zoom, control rectangles) and drive it with the `ui` params below. To *see* it, render offscreen
(`cargo run -p photocraft-ui-egui --example snapshot -- --script '[["ui.menu.invoke", {"id": "filter.cameraRaw"}]]'`
or an `egui_kittest` harness): those embed
viewports, so the dialog is drawn over the main window and appears in the image.

`ui.menu.invoke {"id":"filter.cameraRaw","params":{}}` opens Camera Raw on the active
RGB/Grayscale layer. `params: {"smartFilter": {"layer": id, "index": i}}` opens it on an existing
Camera Raw smart filter instead (as double-clicking the filter in the Layers panel does): the
stored settings over the pixels below that filter, previewed through the filter mask; commit
then runs `layer.smartFilter.setParams` with every setting. `params.ui` accepts `set` (filter settings), `before`, `scope`, `view`, `auto` (true: the Light
sliders from the image's histogram, the panel's Auto button), `commit` and
`cancel`, and while a raw file opens also `demosaic` (below). All parts of one request are validated before any is applied; a rejected request
leaves the settings, view state, preferences and document unchanged (and closes a dialog it
opened). Unknown `ui` or settings properties, non-boolean `before` / `auto` / `commit` / `cancel`, and
`commit` together with `cancel` are errors. Point curves (`pointCurve`, `pointCurveRed`,
`pointCurveGreen`, `pointCurveBlue`) are empty or 2–16 finite points in 0–255 with inputs at
least one level apart. Commit dispatches one `filter.cameraRaw` engine command; a failed commit
keeps the dialog open for correction. Nothing else writes document history.

A raw file opened from a path reads its sidecar (`IMG_0001.xmp` beside `IMG_0001.CR2`, Camera
Raw's `crs:` settings) into the open-time dialog, and Open writes changed settings back
(Preferences › Camera Raw Defaults › Write xmp sidecars). It never writes beside a DNG, over a
sidecar another application wrote (a notice says it was kept), or for a control or MCP request.
Open also applies the other Camera Raw Defaults (Sharpen For as part of the Camera Raw step, then
colour space, bit depth and Open as Smart Object, so the step works on the pixels the dialog
previewed; Apply auto tone fills the dialog), reported as `defaults` in the commit's reply; the
resolution is set when the file opens. With "Open in Camera Raw" off the sidecar and the defaults
apply without the dialog. A sidecar's crop (`crs:HasCrop="True"` with `CropTop` / `CropLeft` /
`CropBottom` / `CropRight`, fractions of the raw as stored, before its Orientation) crops the
document as Open re-develops it, before the Camera Raw step; the dialog previews the whole frame.
A straightened crop (`CropAngle` not 0) is named as not supported and not applied.

**Opening a raw file.** An interactive open (File › Open, Open Recent, drag and drop, the
command line) of a camera raw developed from its sensor data shows this dialog first, titled
"Camera Raw (name)", with **Open** and **Cancel**, as Photoshop opens raws in Adobe Camera Raw.
`ui.inspect.cameraRaw.openingRaw` is then `{name, path, demosaic}`, `demosaic` being the method
the raw is to be opened with (`ahd`, `mhc` or `bilinear`): at first the one the open developed it
with, then whatever `ui.demosaic` or the Demosaic menu at the top of Detail chose. `ui.demosaic`
is accepted only while a raw file opens (an error otherwise) and an unknown method is refused.
Commit (Open) re-develops the raw when the demosaic method differs from the one the open used or
Temperature, Tint, Exposure, Shadows, Highlights, Clarity, Texture or Dehaze changed (as-shot
white-balance gains, develop exposure, and the other five in linear light before the camera's
tone curve, as Camera Raw does for raw files; without an as-shot white balance, or without the file's bytes, they stay RGB
adjustments), applies the remaining settings as one `filter.cameraRaw` step and leaves the
document unmodified; its result is `{document, redeveloped, filter?}`. The preview keeps the
method the file was opened with. Cancel closes the document. `app.open` and other automation
opens never show the dialog. The preference `rawDefaults.openInCameraRaw` (default `true`) turns
it off; `rawDefaults.demosaic` (`ahd` by default, `mhc`, `bilinear`; Preferences › Camera Raw)
is the method the app's raw opens develop with (interactive opens, `app.open` and Place).

Imported PSD Camera Raw filters whose processing settings are all mapped or neutral use this
same editor. `params.__cameraRawPsd` is reserved import/export metadata: preserve it when editing
stored parameters. Other processing fields or versions remain opaque Photoshop filters. See
[PSD Smart Filters](camera-raw-histogram.md#psd-smart-filters) for the supported settings and export
limits.

The response and `ui.inspect.cameraRaw` contain:

- `histogram`: `source` (`before` | `after`), `size`, `approximate`, 256-bin `red` / `green` /
  `blue`, `samples`, `transparent`, `invalid`, per-channel `underflow` / `overflow`, and exact
  endpoint counters `shadows` (≤0) / `highlights` (≥1). Counts describe the bounded preview
  proxy in its RGB sample domain, not full-resolution or ICC display-gamut statistics.
- `previewRevision` (advances only when the proxy is re-developed), `renderMs`, `histogramMs`
  (CPU only; zero on WebAssembly).
- `curveState` (`selected`, `drag`) and `curveRect: [left, top, right, bottom] | null` (null while
  the Curve section is closed). Changing `set.pointCurve` cancels a stale gesture.
- `scope` (the view state below), `hasScopeSelection`, `vectorscope` (`bins`, `samples`,
  `before`, `selectedRegion`) or null, `scopeMs`, `scopeRevision`, `overlayRevision`.
- `pointerReadout` and `samplerReadouts`: `position`, `space` (`rgb` 0–255 in the preview sample
  space, or `lab` through the document ICC profile → D50), `values`, `alpha`; null on invisible
  pixels.
- `hoverSample`: `position`, `rgb` (histogram domain) and `hueSaturation` (turns, 0–1; only
  while the vectorscope is shown), or null.
- `hoveredZone`, `previewRect`, `scopeRect`, `vectorscopeRect`.
- `view` (`zoom: null` for fit, or a numeric factor where 1 = 100%, `center: [u,v]`,
  `hand`), `zoom` (effective factor, null before layout), `sourceSize`, `viewportRect`.
  At 100%, one source pixel maps to one physical display pixel, including on HiDPI displays.
- `previewApproximate`, `detailPending`, `detailError`: whether the visible image still uses
  the proxy, whether full-resolution refinement is running, and any refinement error.

`params.ui.view` changes navigation only: `zoom: "fit" | 0.0001..=16`, `center: [u,v]`
(finite coordinates in 0..=1, clamped to keep the image within view), `hand: bool`. Fit recentres
and follows window resizing; navigation resets when opening a different Camera Raw dialog.
Invalid mixed requests are atomic, just like scope and filter settings. View requests do not
re-develop the proxy or change filter parameters/history.

With the Zoom tool (Z), click toggles Fit / 100%; click-drag right/left scrubs in/out.
Ctrl-drag (Command on macOS) fits a rectangular region. H selects Hand; Space temporarily pans,
including while placing colour samplers. Alt/Option + wheel zooms at the pointer; an unmodified
wheel pans. Pinch zooms. Ctrl/Command +/- zoom, 0 fits, and Alt/Option + Ctrl/Command + 0 shows
100%; Ctrl/Command+Shift-click also selects 100%. Right-click opens Fit / 100% / preset
percentages. Tool double-clicks fit the image.
Text fields retain their keys and wheel gestures over the settings panel still scroll it.

The proxy remains the fast path while changing settings. Where more source pixels are needed,
Camera Raw lazily refines with the **same engine Camera Raw pipeline** at pixelScale=1 and the
same selection/filter-mask coverage. Native refinement runs off the UI thread (one revision at
a time); stale results are discarded. Only a bounded visible crop is uploaded to the GPU, and
pan/zoom reuse developed pixels. Before and neutral settings read the original pixels directly.
Absurd proxy domains (over 512 MP, including distant sparse off-canvas pixels) are rejected
before reading pixels. Full-resolution refinement is capped at 64 MP to bound the existing full-image engine pipeline;
above that it explicitly reports unavailability and keeps the proxy. Oversized viewport crops
also retain the proxy. Without a browser worker, wasm explicitly retains the filtered proxy
rather than block its UI; Before and neutral settings still crop the original source pixels.
The histogram and vectorscope continue to analyse the bounded proxy; readouts and clipping
warnings use the full-resolution pixels once refinement is visible.

`params.ui.scope` changes presentation only: `shadows` / `highlights` (clipping warnings, U / O),
`lab`, `samplerTool` (S), `vectorscope`, `selectedRegion` (requires a document selection),
`redRight`, `hideSkinLine`, `floating`, `floatingRect: [left, top, right, bottom]` (200×150 to
4096×4096 points), `sample: [u,v] | null`, and the probe list: `samplers: [[u,v], …]` replaces it,
or `clearSamplers: true`, `removeSampler: index` and `addSampler: [u,v]` edit it, applied in that
order (the two forms can't be combined). Coordinates are normalized to the displayed proxy; at
most nine probes. `tone: {zone: "blacks|shadows|exposure|highlights|whites", delta}` adjusts the
same parameter as a histogram drag (`reset: true` sets it to 0); Exposure clamps to ±5 stops, the
others to ±100.

Hover, probe movement, theme changes and panel resizing never re-develop the image; Before/After
and region changes rebuild only the dependent analysis. Display options and the floating panel
geometry persist in preferences `dialogs["filter.cameraRaw.scope"]`; probes and vectorscope
visibility reset when the dialog opens. HDR scopes are not implemented. See
[camera-raw-histogram.md](camera-raw-histogram.md).

### Editing and composing actions

Newly recorded Select Layer steps store the layer name instead of a document-specific ID,
and the Actions panel shows `Select Layer (Background)`. Duplicate names include a zero-based
`occurrence` in document walk order (including layers inside groups); keep that order consistent
between source and target documents. A missing name or occurrence stops playback; a name without
an occurrence is rejected when ambiguous. Names are captured at selection time, so a later
rename in the action does not change the earlier target. Numeric `layer` IDs remain supported
for direct commands and older recordings, which the panel labels `Select Layer (ID 26)`.
String-valued `layer` targets from imported Photoshop actions keep main's topmost-name matching
and show the same named label; `remove` selection mode is supported for either target form.
Re-record old Select Layer steps: their original names cannot be recovered from an ID alone.

Creating an action scrolls its row into view; newly recorded steps are revealed immediately.
Drag a step above or below another step in the same action to reorder it. Drag an action header
to reorder the action list. The insertion line marks the drop position; dragging near the rows'
top or bottom scrolls the list. Reordering is saved with the actions and does not undo image edits.

While recording, press a function key assigned to another action (or play it from the panel).
The recorder adds **Play Action: <name>** as one step, and the called action still executes.
Playback resolves the name each time, so editing or moving the called action does not freeze or
retarget the caller. Reassigning F6 later does not change an already recorded named call.
Missing actions, recursive calls and nesting beyond 16 levels fail visibly; a child failure stops
the parent before its next step. Every nested command retains the normal automation permission check.
Existing recordings containing expanded commands remain unchanged; remove those steps and record
the named call again if desired.

Actions sit in **set folders** (`set` on `actions.list` / `actions.get`, filled by Load Actions,
written by Save Actions, changed with `actions.assignSet`): the panel shows loose actions first,
then each set as a collapsible folder (`ui.actions.collapsedSets`); dropping an action among
another set's rows moves it into that set. Each step has Photoshop's two toggles: the check
(`actions.toggle`, skipped when off) and the **dialog** toggle (`actions.dialog`). Playing a
step with its dialog on opens that command's dialog seeded with the recorded values and pauses:
the play result carries `paused: {step, id, dialog}`, OK runs the dialog's values and continues
from the next step, Cancel stops the action. Agents (`automation_input`) play headlessly with the
recorded values. The panel menu's **Insert Stop…** adds an `actions.stopMessage` step after the
selected step (`actions.insert` takes any command id and params). `actions.conditional {if, then,
else}` is Photoshop's Insert Conditional as a step: it tests the document or active layer
(`always`, `landscape`, `modeIsRGB`, `hasLayers`, `isBackground`, `hasPixelMask`… see its params)
and plays the matching action by name, failing the caller when that action fails.

Layer-panel **Quick Export as PNG** exports every selected layer as a separate PNG. A single
Save dialog chooses the first filename; remaining files are numbered siblings with sanitized
layer names. Selection is captured before opening the dialog; an unselected layer is excluded.

## Shared panel docking

Panel arrangements support tab grouping and reordering, horizontal and vertical splits,
and movable, resizable floating groups. Drag a panel tab or a group's drag bar, or use its
context menu. On the desktop a floating group opens in its own OS window; on Wayland, in the
web build and for the Studio Properties card it stays inside the application window.

The shared layout begins with the existing workspace on the first docking operation.
Workspace saves keep its groups, active tabs, split sizes, floating geometry, and the
positions of hidden panels. Resetting a built-in workspace restores its default dock.

The docking commands are craft-ui's shared vocabulary (`DockCommand`). Panels may be named
by ID or label, and `onto` is accepted for `anchor`.

- `window.panel.move {panel, anchor, zone?, before?, group?, placement?}` moves a panel into the
  target group. `zone` is `tab` (default), `center`, `left`, `right`, `top`, `bottom`, `above`
  or `below`; `before` reorders tabs by panel ID; `group: true` moves the panel's whole group.
- `window.panel.float {panel, x?, y?, width?, height?, group?, column?}` detaches a panel (at
  400, 140 and 300x400 by default) or its group.
- `window.panel.dock {panel, anchor?, zone?, before?, group?, side?}` returns a floating panel to
  the dock place it floated from when possible, or to the supplied destination.
- `window.panel.activate {panel}` reveals and selects a panel, restoring its saved
  position when possible. `window.panel.close {panel}` hides it; `window.panel.closeGroup` and
  `window.panel.closeOthers` close its group or the group's other panels.
- `window.panel.minimize {panel, minimized?}` collapses a floating window to its title bar.
- `window.panel.window {panel, native?}` floats a docked panel's group and gives its floating
  window its own OS window. On the desktop every floating window has one, except the Studio
  themes' Properties card, which stays over the canvas, and on Wayland, where floating windows
  stay in the main window. The web refuses the command: floating panels stay in the page.
- `ui.dock {operation, …}` takes the shared `ui.dock` operations (`open`, `close`, `activate`,
  `float`, `moveFloating`, `move`, `setStackOpen`, `resizeStack`, `resizeSplit`) or `{action}`.
- `window.workspace.lock {locked?}` sets Lock Workspace; `window.workspace {name}`,
  `window.workspace.new {name}`, `window.workspace.delete {name}` and `window.workspace.reset`
  run the Window › Workspace commands.

Panel IDs are stable across themes. Invalid IDs, non-finite or invalid geometry, and
invalid destinations return an error without changing the arrangement.

Lock Workspace prevents moving, detaching, and closing panels; activating a panel remains available.

`window.panel.layout {action}` also accepts the shared, externally tagged action schema.
For example, `{"action":{"MoveFloating":{"panel":"properties","rect":[44,66,360,450]}}}`
updates a floating group's position and size; `{"action":{"ResizeSplit":{"path":[],"size":{"Ratio":0.35}}}}`
resizes the root divider (`false`/`true` path entries select first/second children).
`Move` with `placement: {"Tab":{"before":"swatches"}}` reorders tabs, and
`SetStackOpen {panel,open}` / `ResizeStack {panel,height}` control accordion entries.
The UI dispatches these same commands. Unknown panel IDs, invalid geometry, and stale
split paths return an error without changing the workspace.

The `docking` object in `ui.state` and in saved workspaces is craft-ui's `Workspace`:
`version` (2), `layout`, `hidden` (each closed panel with its return place), `saved` and
`locked`. `dockingReturns` holds where each floating panel docks back, and
`dockingCollapsed` the panels of collapsed custom groups. Any other saved `docking` value,
such as a bare layout with `dockingHidden`, loads as the default layout, built from the
saved `panels`, `dockTabs` and `dock`.

The existing `ui.set` panel visibility, `dockTabs` selection and `dockWidth` controls
remain available after customization. Width requests use the window-dependent range
250..max(520, window width − 400), with achieved widths subject to column minimums
and iconic caps; constrained dock-edge rendering still reserves canvas space. Named
`dock.hidden_tabs` and intact native-group collapse settings are also preserved. A
legacy `dock` replacement that changes flat group order or heights is rejected after
customization: use `window.panel.layout` to change a custom split tree. A replacement
that changes legacy collapse settings is also rejected when a custom root group mixes
panels from different native groups; use `window.panel.group` to collapse or expand
that group. Validation is atomic across mixed `ui.set` requests.

`window.panel.group {panel, operation}` applies `close`, `collapse`, `expand`, `up`,
or `down` to the panel's entire current group. With `operation:"move"`, provide
`anchor` and optional `zone`/`before` (as for panel.move), or a serialized `placement`,
to transfer all members atomically while preserving their order and selecting the
requested `panel`.
A floating group's drag bar or title bar also transfers the whole group when dropped on a
dock target. The panel menu and icon rail remain
available in custom workspaces. `window.panel.<id> {show:true}` always reveals, selects
and expands the panel, including when another tab is selected. Workspace snapshots
retain custom collapse settings and Timeline visibility.

### Frame Tool controls

`ui.set {"tool":"frame","frameShape":"rectangle|ellipse|triangle|polygon|custom","frameSides":5,"frameTarget":"frame|content|both"}` selects creation options or the target inside the active frame. `ui.inspect` includes `frameTool`. `layer.frame.info {"layer":id}` queries geometry, stroke, and content without adding history. Frame edits use `layer.frame.set`, `layer.frame.fit`, `layer.frame.convert` and `layer.frame.setContent`; placement accepts `frame: id` to target an explicit frame or `frame: false` to place outside frames. See [Frame Tool behavior and persistence limits](frame-tool.md).

### Select the layer under the pointer

Assign **Select Layer Under Cursor** in Keyboard Shortcuts to choose the topmost visible, pickable layer beneath the canvas pointer. Empty pixels and points outside the document leave the selection unchanged; dialogs, strokes and brush-resize gestures block it. The command follows zoom, pan, view rotation and horizontal flipping. Agents can invoke `ui.menu.invoke {"id":"layer.selectUnderCursor"}` after moving the screen pointer with `ui.move {"x": ..., "y": ...}`. The command has no default shortcut.