# Driving EffectCraft from agents

Everything in EffectCraft is an engine command with a stable id and JSON params. Menus, shortcuts,
panel gestures, the CLI, the control channel and MCP all go through the same commands, so anything a
user can do, an agent can do too. There are three ways in:

| Interface | Best for | Needs a window |
|---|---|---|
| **MCP** (`effectcraft-cli mcp`) | Claude Code and other MCP clients | no (headless), or yes with `--bridge` |
| **CLI** (`effectcraft-cli exec/get/set/...`) | one-shot scripting and CI; JSON output with `--json` | no |
| **Control channel** (`effectcraft --control 9877`) | driving and seeing the live UI; see [control-protocol.md](control-protocol.md) | yes |

## MCP setup

Build once with `cargo build --release -p effectcraft-cli`, then register the server. For Claude
Code, add a `.mcp.json` at the project root:

```json
{
  "mcpServers": {
    "effectcraft": {
      "command": "/path/to/effectcraft/target/release/effectcraft-cli",
      "args": ["mcp"]
    }
  }
}
```

This repository ships a ready-made [`.mcp.json`](../.mcp.json): `effectcraft` (headless, demo
project loaded) and `effectcraft-app` (bridged to a desktop app started with `--control 9877`). Both
run through `cargo run --release`, so the first start compiles; run
`cargo build --release -p effectcraft-cli` once beforehand to avoid an MCP startup timeout.

You can also register it from the command line:
`claude mcp add effectcraft -- /path/to/target/release/effectcraft-cli mcp`. Other clients (Claude
Desktop, Cursor and the like) take the same `command` and `args`.

- **Headless** (`["mcp"]`): an in-process session with no window. Add `"--demo"` or
  `"--project", "file.ecproj"` to start with content. Startup is instant. It renders on the CPU
  unless you add `"--gpu"` (`["mcp", "--gpu"]`), which attaches the GPU compositor on a device of
  its own; if no adapter is usable the server says why and exits. `get_project`'s `renderer`
  (`render.backend`) reports `active` (`gpu` / `cpu`) and, on the CPU, `why`.
- **Bridge** (`["mcp", "--bridge", "9877"]`): drives a running `effectcraft --control 9877`, so you
  see every change live. Bridge mode adds `screenshot` and the `ui_*` tools.

The server speaks JSON-RPC 2.0 over stdio, one message per line, and supports MCP protocol versions
2025-06-18, 2025-03-26 and 2024-11-05 (`initialize`, `ping`, `tools/list`, `tools/call`).

### Tools

| Tool | What it does |
|---|---|
| `list_commands {filter?, enabled_only?, schemas?}` | Discover command ids, their param docs (and, with `schemas`, a JSON Schema each), and whether each can run now. |
| `describe_command {command}` | One command in full: label, menu, shortcut, params doc, JSON `schema`, enabled / `why`. |
| `execute_command {command, params?}` | Run any command (undoable). Unknown parameter keys are rejected with the accepted list. |
| `get_state` | Editor state (active comp, time, selections, tool) plus `app`: version, command and effect counts, export formats, parity summary. |
| `run_script {code, name?}` | Run JavaScript with the After Effects-style scripting object model (`app.project`, `comp.layers.addText(…)`, `layer.property("ADBE Transform Group").property("ADBE Position").setValueAtTime(…)`…). Returns `{ok, result, output, error: {message, line, column}}`; edits are undoable. |
| `get_project` / `get_comp {comp?}` | Project items, comp settings and layers. |
| `get_layer {layer, comp?, time?, depth?, flat?}` | A layer's property tree (`depth` limits how many group levels expand). Every node has a `path`. |
| `get_property {layer, path, comp?, time?}` | Value at a time, keyframes and expression. |
| `set_property {layer, path, value?, time?, expression?, comp?}` | Sets a static value. With `time` it sets a keyframe; with `expression` it sets an expression. |
| `add_keyframe {layer, path, time+value \| keys:[...], interpolation?, comp?}` | Adds keys, then optionally applies linear/bezier/hold/easyEase. |
| `list_effects {filter?}` | Effect ids, names, categories, GPU / 32-bpc support and parameters. |
| `list_fonts {query?, rescan?}` | Font families text layers can use, bundled and installed, with their styles, origin and own-language name; `rescan` picks up fonts installed since launch. |
| `add_effect {layer, effect, values?, comp?}` | Apply an effect and set its parameters in one call and one undo step (a failing value leaves nothing applied); returns the instance path (`effects/#n`) and its parameter paths. |
| `render_frame {comp?, time?, max_side?, path?, inline?, transparent?}` | Returns a PNG image of a frame; `transparent: true` keeps the alpha (as an RGB + Alpha render writes it) instead of compositing over the comp background. |
| `open_project {path \| demo \| new}` / `save_project {path?}` | Open and save files. |
| `undo {steps?}` / `redo {steps?}` | History. |
| `history {goto?}` | The branching undo history (History panel): every state with its index, id, label, branch depth and whether it's current; `goto` (an index or id) jumps to any state, on any branch, without losing the others. |
| `script_ui {action?, window?, widget?, value?, result?}` | Drive ScriptUI windows that scripts opened: `list` (default) the open windows, `get` a window's control tree, `click` a button / checkbox / radio button, `set` text, a slider or a list item, `close` a window (`result`: what a dialog's `show()` returns, default 2 = Cancel). |
| `batch {steps: [{command, params}], label?, atomic?}` | Several commands in one call and one undo step (`engine.batch`); `"$N.key"` in a param is step N's result (`"$1.layer"`). A failing step rolls the batch back and names the step. |
| *(bridge)* `screenshot {panel?, id?, max_side?, path?}`, `ui_inspect`, `ui_elements {prefix?}`, `ui_click`, `ui_drag`, `ui_key`, `ui_type`, `ui_set`, `control {method, params}` | Look at and operate the live window. |

Layers are referenced by id (from `get_comp`), `"#n"` (1-based index from the top) or name. Comps are
referenced by id or name, and default to the active comp. Property paths come from `get_layer`, for
example `transform/position`, `transform/opacity`, `effects/#1/blurriness` or `@57` (by uid). Times
are in seconds. Keyframe times are layer time, which equals comp time unless the layer is offset or
stretched.

Command params are checked against each command's `params` doc. An unknown key, such as
`layer.select {"index": 2}`, returns an error that lists the accepted keys (here `layers, add, toggle`)
instead of being ignored.

### A typical session

1. `execute_command {"command":"comp.new","params":{"name":"Intro","width":1920,"height":1080,"frameRate":30,"duration":4}}`
2. `execute_command {"command":"layer.newText","params":{"text":"Hello","size":160,"fill":"#ffffff"}}` returns `{"layer": 2}`.
3. `add_keyframe {"layer":2,"path":"transform/position","keys":[{"time":0,"value":[-300,540]},{"time":1.5,"value":[960,540]}],"interpolation":"easyEase"}`
4. `execute_command {"command":"effect.apply","params":{"layer":2,"effect":"Gaussian Blur"}}`, then `set_property {"layer":2,"path":"effects/#1/blurriness","value":8}`
5. `render_frame {"time":1.0}` lets you look at the result, and `save_project {"path":"intro.ecproj"}` saves it.

### Cookbook

Short recipes; every step is one tool call.

| Goal | Calls |
|---|---|
| Orient yourself | `get_state` → `get_project` → `get_comp {}` |
| Find the right command | `list_commands {"filter":"mask"}` → `describe_command {"command":"mask.new"}` (params + JSON Schema) |
| Title card | `execute_command comp.new {...}` → `execute_command layer.newText {"text":"Hi","size":120}` → `render_frame {"time":0}` |
| Animate | `add_keyframe {"layer":2,"path":"transform/scale","keys":[{"time":0,"value":[0,0]},{"time":0.5,"value":[100,100]}],"interpolation":"easyEase"}` |
| Effect with settings | `list_effects {"filter":"glow"}` → `add_effect {"layer":2,"effect":"Glow","values":{"threshold":40,"radius":30}}` → `set_property {"layer":2,"path":"effects/#1/intensity","value":2}` |
| Key a green screen | `add_effect {"layer":2,"effect":"Keylight (1.2)"}` → `execute_command effect.pickColor {"layer":2,"effect":1,"param":"screenColour","x":20,"y":20,"average":true}` (a screen pixel, layer space; samples the effect's input) → `set_property {"layer":2,"path":"effects/#1/screenMatte/clipBlack","value":10}` → `render_frame {"transparent":true}` |
| Drive with an expression | `set_property {"layer":2,"path":"transform/rotation","expression":"time*90"}` |
| Inspect a layer | `get_layer {"layer":2,"flat":true}` (every property with its `path`, value, key count) |
| Check the result | `render_frame {"time":1.5,"max_side":640}`; in bridge mode `screenshot {"panel":"Timeline"}` |
| Undo a mistake | `undo {}`, or `history {}` then `history {"goto": n}` |
| Missing media after opening | `execute_command footage.check {"wait":true}` → `{checked, missing, probed}`; then `file.findMissing {"what":"footage"}` |
| Save | `save_project {"path":"out.ecproj"}` |

The desktop app checks footage in the background after every open (a "Checking footage" job in
the Progress panel, `jobs.list`); headless sessions run `footage.check` when they want it.
### Cookbook (from end-to-end QA)

The scenarios in `crates/automation/tests/qa/` and `apps/effectcraft-cli/tests/qa_template.rs`
build real projects through these interfaces; they are worked examples of everything below.

* **Name things when you create them**: `layer.newText`, `layer.newShape`, `layer.newSolid`,
  `layer.newNull`, `layer.newCamera` and `layer.newLight` take `name`, so later calls can say
  `"layer": "Title"`. A reference that matches no layer is an error, never a silent no-op.
* **Nested comps**: `comp.settings {preserveFrameRate, preserveResolution}` (Composition Settings ▸
  Advanced); `comp.info` / `get_comp` report both. A precomp layer shows nothing outside its
  nested comp's span.
* **Several footage items at once**: `file.newCompFromSelection {single, dimensionsFrom, duration,
  sequence, overlap, overlapDuration, transition, addToRenderQueue}` is one undo step (select the
  items first: `project.select`).
* **Locked layers** are left alone: `edit.clear`, `layer.arrange`, `layer.transform` and
  `layer.centerAnchor` skip them and fail when every target is locked ("… is locked"); Select
  All and `layer.selectNext` / `selectPrevious` step over them. Unlock with
  `layer.setSwitch {"layers": [...], "switch": "lock", "value": false}` or `layer.unlockAll`.
* **Solid Settings**: `layer.settings {layer, name?, color?, width?, height?, pixelAspect?,
  affectAll?}` edits a solid or adjustment layer's solid (and renames the layer and the solid).
  A solid shared by several layers (duplicates share theirs) changes for all of them unless
  `affectAll: false`, which gives this layer its own copy; the reply names it (`{layer, solid}`).
  Cameras and lights take their own settings through the same command.
* **Use the paths replies give you**: `effect.apply` returns `{effects: [uid], paths:
  ["effects/#2"]}`; `layer.addShapeItem {kind, group?: uid|path}` returns `{uid, path}` (e.g.
  `contents/group/contents/gfill`), ready for `set_property`. `@uid` works as a whole path.
* **One call, one undo step**: `batch {"steps":[{"command":"layer.newShape","params":{"kind":"ellipse","name":"Ring"}},{"command":"layer.addShapeItem","params":{"layer":"$1.layer","kind":"trim"}},{"command":"prop.addKey","params":{"layer":"$1.layer","path":"transform/opacity","time":0,"value":0}}]}`
  (a string param that is exactly `"$N"` or `"$N.key"` is replaced; `$2.path` is the trim's path).
* **Expressions**: `set_property`/`get_property` replies carry `evaluated` (what renders) next to
  `value` (the keyframed value) and `expressionError` when the expression fails. An expression with
  a syntax error is kept but disabled, so it renders `value` and reports the syntax error.
* **Keyframes like a person**: `keys.select {keys, toggle: true}` (Shift+click), `keys.selectEqual`
  / `selectPrevious` / `selectFollowing`, `keys.move {delta, merge}` (steps sharing a merge key are
  one drag: each applies to the keys as they were before it, so a key passed over survives) and
  `keys.transform {…, merge, fromStart: true}` (values are the whole transform since the drag
  started). Keys of locked layers can't be selected. Copy / paste: `keys.copy`, then `keys.paste`
  at the current time (keys copied from several layers go to as many selected layers in order).
  `time.nextKey` / `time.previousKey` / `keys.selectAll` take `visible: [{layer, prop}]` to act
  only on those properties (the Timeline passes its revealed ones, as J / K and Ctrl+Alt+A do).
* **Easing with Keyframe Velocity**: select keys by path, `keys.select {"keys":[{"layer":"Ring","path":"contents/trim/end","time":0}]}`,
  then `keys.velocity {"outSpeed":0,"outInfluence":33.33}`.
* **Gradients**: `set_property {"path":"contents/gfill/colors","value":["#0080ff","#ffff00"]}` or
  `{"colors":[[0,"#0080ff"],[1,[1,1,0]]],"opacities":[[0,1],[1,0.5]]}`.
* **Image sequences** import at 30 fps (Settings ▸ Import); `file.interpretFootage {"items":[id],
  "frameRate":12}` conforms them (the item and layers that ran to its end get the new length).
* **Masks**: `layer.addMask {layer, shape: rect|ellipse, rect}` first, then `layer.mask.set
  {field: feather|expansion|opacity, value}`.
* **Renders**: `renderQueue.add {comp, format: h264|prores|webm|png…, channels: rgba,
  proresProfile: 4444, output}` then `renderQueue.render {"wait": true}`. Check a render by
  importing it (`file.import`, `file.newCompFromSelection`) and `render_frame {transparent: true}`
  for its alpha (ProRes 4444 and WebM VP9 alpha both read back as straight alpha).
* **Essential Graphics**: controls can be addressed by name (`essential.set {"layer":"#1",
  "control":"Title","value":"John Smith"}`); a command that targets an explicit `comp` runs even
  when the active comp would disable it (`essential.exportTemplate {"comp":"Lower Third", …}`).
* **History**: Levels of Undo defaults to 32 (`prefs.set {"key":"general.undoLevels","value":99}`);
  `history` lists branches and `history {"goto": id}` jumps between them. A command that changes
  nothing (a value set to what it already is) records no undo step. `get_state` reports `dirty`
  (unsaved changes); it follows undo, so undoing back to the saved state clears it.
* **Unsaved changes**: commands run through MCP / `engine.execute` never ask to save. In the
  desktop app, `ui.menu.invoke` of a command that closes a modified project (`file.open`,
  `file.newProject`, `file.closeProject`, `file.revert`…) and the window's close button show the
  Save / Don't Save / Cancel prompt (`ui_click` on `dialog.unsaved.save` / `dontSave` / `cancel`;
  `dialog.unsaved.revert` for Revert); the control channel's `app.quit {"force": true}` skips it.

### Motion tracking

Trackers live on the tracked layer (`Motion Trackers ▸ Tracker n ▸ Track Point n`) and are driven
with `track.*` commands. `track.analyze` runs in the background in the app (poll `track.status`);
pass `"wait": true` to block until it finishes, which is what the CLI and headless MCP want.

1. `execute_command {"command":"track.motion","params":{"layer":"clip.mov"}}` creates a Transform
   tracker (Motion Target: the layer above). Use `track.stabilize` for Stabilize, or `track.new` with
   `kind` `transform|stabilize|affine|perspective|raw` and `rotation`/`scale`.
2. `execute_command {"command":"track.setPoint","params":{"point":1,"center":[812,440],"featureSize":[40,40],"searchSize":[96,96]}}`
3. `execute_command {"command":"track.analyze","params":{"direction":"forward","wait":true}}` keys Feature
   Center, Confidence and Attach Point on every frame from the current time to the layer's end.
4. `execute_command {"command":"track.apply","params":{"dimensions":"xy"}}` keys the target's Position
   (and Rotation/Scale), the layer's own Anchor Point and Position for Stabilize, or a Corner Pin
   effect for `affine`/`perspective` tracks. `track.options` sets the channel, blur/enhance,
   adapt-feature and "If Confidence is Below" behaviour; `track.status` reports the track points.

```sh
effectcraft-cli run clip.ecproj track.motion '{"layer":"#2"}' \
  track.setPoint '{"point":1,"center":[812,440]}' \
  track.analyze '{"wait":true}' track.apply '{}' --save
```

### Mask tracking and Mask Interpolation

`track.mask` follows the pixels inside a mask and keys its Mask Path on every frame (vertices and
tangents move with the fitted motion). `method` is `position`, `positionScale`,
`positionScaleRotation` (the default, also kept as the Tracker panel's Method), `positionScaleRotationSkew`,
`perspective`, `faceOutline` (Face Tracking (Outline Only): the mask, drawn around a face, becomes
the face outline on every frame) or `faceDetailed` (Face Tracking (Detailed Features): also keys a
Face Track Points effect with one point per landmark — eyebrows, eyes, pupils, nose tip,
nostrils, mouth corners and lips, chin, jaw); `direction` is `forward|backward|frameForward|frameBackward` from the current
time (or `start` / `end` in seconds). Like `track.analyze` it runs in the background in the app
(progress in `track.status` under `mask`, `track.stop` cancels and keeps what was tracked) and is
one undo step; `"wait": true` blocks. `track.extractFaceMeasurements {layer?}` (Extract & Copy Face
Measurements) keys a Face Measurements effect from the Face Track Points (head position, scale and
orientation X/Y/Z, eye openness, eyebrow distance from eye, mouth openness, width and offset), puts
those keys on the keyframe clipboard and returns them per frame plus a tab-separated `clipboard`
text.

Face tracking's trained model works like Roto Brush's (below): `face.models` lists the built-in
tracker and MediaPipe Face Landmarker with its authors and licence; `face.model.download {id}` /
`face.model.install {path, id?}` install it (verified); `face.model.select {id:
classical|mediapipe-face}` chooses it; `face.model.remove {id}` deletes it. Downloads and loading
run in the background; `"wait": true` on download, install or select returns once the model is in
use (or with its error), which scripts need before tracking. `track.mask` with a
face method returns `faceModel`, the engine it tries first (the classical one when the model finds
no face in the mask).

```sh
effectcraft-cli run clip.ecproj face.model.download '{"id":"mediapipe-face","wait":true}' face.model.select '{"id":"mediapipe-face","wait":true}' \
  track.mask '{"layer":"#1","mask":1,"method":"faceDetailed","direction":"forward","wait":true}' --save
```

`mask.interpolate` (Window ▸ Mask Interpolation ▸ Apply) adds in-between Mask Path keys between
each pair of selected Mask Path keys (or the existing keys at `times`, in seconds), giving both
ends the same vertex count with a matched correspondence. Options: `keyframeRate` (number or
`"auto"` = the comp rate), `keyframeFields`, `linearVertexPaths`, `bendingResistance`, `quality`,
`addVertices` (number or `false`) with `addVerticesUnit` `pixels|total|percent`, `matchingMethod`
`auto|curve|polyline`, `oneToOne`, `firstVerticesMatch`. `mask.interpolationOptions` sets the
panel's defaults.

```sh
effectcraft-cli exec track.mask '{"layer":"#2","mask":1,"method":"perspective","wait":true}' clip.ecproj --save
effectcraft-cli exec mask.interpolate '{"layer":"#2","mask":"Mask 1","times":[0,2],"addVertices":10}' clip.ecproj --save --json
```

### Warp Stabilizer

Effect ▸ Distort ▸ Warp Stabilizer (`effect.apply {"effect":"Warp Stabilizer"}`), Animation ▸ Warp
Stabilizer VFX and the Tracker panel's button (`track.warpStabilizer`, which applies the effect and
starts analysing) stabilize a layer. `warp.analyze {layer?, effect?, wait?}` analyses every frame
between the layer's In and Out points in the background ("Analyzing in background (step 1 of 2)",
then "Stabilizing..."; `warp.status` reports `progress`, `banner`, whether the effect is
`analyzed`, and the current frame's `warp` matrix, `autoScale` and `crop`); `warp.cancel` stops it
without writing anything. The analysis is stored in the effect (saved with the project) and is
one undo step; trimming, slipping, time-remapping or replacing the layer's source clears it and
the app re-analyses automatically (headless: run `warp.analyze` again). Settings are ordinary
properties under the instance's groups, e.g. `effects/#1/stabilization/result` (0 Smooth Motion,
1 No Motion), `effects/#1/stabilization/smoothness`, `effects/#1/stabilization/method`,
`effects/#1/borders/framing` (0 Stabilize Only … 3 Stabilize, Synthesize Edges),
`effects/#1/borders/autoScale/maximumScale`, `effects/#1/advanced/showTrackPoints`. Method 3
(Subspace Warp, the default) bends a mesh per frame to the smoothed feature trajectories, so
scenes with depth stabilise where one perspective transform cannot;
`effects/#1/advanced/rollingShutterRipple` (0 Automatic Reduction, 1 Enhanced Reduction: a finer,
softer mesh) tunes it.

```sh
effectcraft-cli run shaky.ecproj track.warpStabilizer '{"layer":"#1","wait":true}' \
  prop.set '{"layer":"#1","path":"effects/#1/stabilization/result","value":1}' --save
effectcraft-cli exec warp.analyze '{"layer":"#1","wait":true}' shaky.ecproj --save --json
effectcraft-cli exec warp.status '{"layer":"#1"}' shaky.ecproj --json
```

### 3D Camera Tracker

Animation ▸ Track Camera and the Tracker panel's button (`track.camera {layer?, shotType?:
fixed|variable|specify, aov?, solveMethod?: auto|typical|flat|tripod, detailed?, lensDistortion?,
undistort?, wait?}`) apply
Effect ▸ Perspective ▸ 3D Camera Tracker (or reuse the layer's) and analyse it in the background:
"Analyzing in background (step 1 of 2)" tracks features, "Solving camera" solves.
`camera.analyze {layer?, effect?, wait?}` re-runs it, `camera.cancel` stops it without writing
anything. `camera.solveStatus` reports `progress`/`banner`, `analyzed`, `solved`, `methodUsed`,
`averageError` (pixels), `focalLength`, `horizontalAngleOfView`, the current frame's `camera`
(position, orientation, zoom), `groundPlane` and the solved `lensDistortion` (`k1`, `k2`, normalised by
half the frame diagonal) when Solve Lens Distortion (`effects/#1/advanced/lensDistortion`, also on
with Detailed Analysis) is on; `effects/#1/advanced/undistort` renders the footage undistorted so
the solved camera's 3D layers line up. `camera.points {time?}` lists the solved points
visible now with their `id`, `comp` position, `depth`, `world` position and `error`.

Select points with `camera.selectPoints {points, add?, toggle?}` (the viewer's click / Shift-click /
marquee), then the right-click menu's commands: `camera.setGroundPlane {points?}` (Set Ground Plane
and Origin), `camera.createFromSolve {kind: text|solid|null|shadowCatcher, points? | target:
{center, normal, size?}, multiple?}` (Create Text / Solid / Null / Shadow Catcher, Camera and Light,
Create Multiple …), `camera.deletePoints {points?, wait?}` (re-solves; with Auto-delete Points
Across Time the same feature's other tracks go too) and `camera.create` (the Create Camera button).
Each is one undo step; the first create adds the one-node "3D Tracker Camera" keyed on every frame.
Changing the layer's frames clears the analysis; changing `effects/#1/shotType`,
`effects/#1/horizontalAngleOfView`, `effects/#1/advanced/solveMethod` re-solves the stored tracks.

```sh
effectcraft-cli run shot.ecproj track.camera '{"layer":"#1","wait":true}' \
  camera.points '{}' --json
effectcraft-cli run shot.ecproj camera.createFromSolve '{"kind":"solid","points":[12,40,77]}' --save
```

### Roto Brush & Refine Edge

The Roto Brush tool (Alt+W cycles Roto Brush / Refine Edge) paints in the Layer panel; agents use
`roto.stroke {layer, kind: fg|bg|refine|refineErase, points: [[x, y], …], frame?, radius?}`
(layer pixels, layer frames). The first foreground stroke applies the Roto Brush & Refine Edge
effect and sets the base frame with a span of 20 frames each side. `roto.propagate {layer,
direction?: forward|backward|both, to?, wait?}` segments the span (in the background unless
`wait`); strokes on any other frame correct it and propagation restarts from there.
`roto.span {start?, end?}`, `roto.freeze {wait?}` / `roto.unfreeze`, `roto.clearStrokes {frame?,
kind?}`, `roto.cancel` and `roto.options {diameter?, refineDiameter?, view?: alphaBoundary|alpha|
alphaOverlay|none}` complete the set; every edit is one undo step. `roto.status {layer, frame?,
matte?, compute?, compareTo?}` reports the base frame, span, computed and stroked frames, frozen
state, job progress and, for a frame, the matte's area, centroid, RLE matte and IoU against a
reference. Matte settings are ordinary properties (`effects/#1/rotoBrushMatte/searchRadius`,
`effects/#1/refineEdgeMatte/decontaminateEdgeColors`, …).

Trained model (Roto Brush 2.0 / 3.0):
- `roto.models` lists the built-in engine and every registered model, with its authors,
  licence, size, URL, SHA-256 and whether it is installed, selected and active.
- `roto.model.download {id}` fetches and verifies the official weights in the background;
  `roto.model.install {path, id?}` installs a file you already have.
- `roto.model.select {id: classical|mobilesam}` chooses which one Roto Brush uses. Loading runs
  in the background; `"wait": true` (also on download and install) returns once it is in use.
- `roto.model.remove {id}` deletes the installed weights.
- The `version` property (`effects/#1/version`: 0 = 1.0, 1 = 2.0, 2 = 3.0) picks between the
  classic engine (1.0) and the chosen model (2.0, 3.0).

```sh
effectcraft-cli run clip.ecproj roto.model.install '{"path":"mobile_sam.pt"}' roto.model.select '{"id":"mobilesam","wait":true}' \
  roto.stroke '{"layer":"#1","points":[[300,200],[360,230]],"radius":10}' roto.propagate '{"layer":"#1","wait":true}' --save
```

```sh
effectcraft-cli run clip.ecproj roto.stroke '{"layer":"#1","points":[[300,200],[360,230]],"radius":10}' \
  roto.stroke '{"layer":"#1","kind":"bg","points":[[40,40],[600,40]],"radius":12}' \
  roto.propagate '{"layer":"#1","wait":true}' roto.freeze '{"layer":"#1","wait":true}' --save
```

### Text: styles and editing

Source Text holds character style runs and per-paragraph settings. `layer.setText` changes the
whole layer, or only characters `range: [start, end]` (character indices): character attributes
(`font`, `size`, `fill`, `tracking`, `kerning: metrics|optical|<1/1000 em>`, `tsume`,
`baseline: superscript|subscript`, `allCaps`…) split the text into runs; paragraph attributes
(`justify`, `indentLeft`, `indentFirst`, `spaceBefore`, `direction`, `composer`,
`hangingPunctuation`…) apply to the paragraphs the range touches. Editing mirrors the Type tool:

1. `layer.newText {"text":"", "box":[100,100,600,300], "edit":true}` makes paragraph text and
   starts editing (`position` instead of `box` makes point text; `vertical: true` vertical type).
2. `text.insert {"text":"Hello world"}` types at the caret (replacing the selection);
   `text.setSelection {"start":6,"end":11}` selects "world"; `text.moveCaret {"to":"wordLeft",
   "extend":true}` moves like the arrow keys; `text.delete {"word":true}` is Alt+Backspace.
3. `layer.setText {"range":[6,11], "size":40, "fill":"#ff5500"}` styles the selection (the
   Character panel does the same); with an empty range it sets the style the next typed text takes.
4. `edit.copy`, `edit.paste`, `edit.pasteTextMatchFormatting` and `edit.pasteTextFormattingOnly`
   work on the selected text; `text.endEdit` commits (an empty Type-tool layer is removed).

Fonts: `text.fonts` (MCP `list_fonts`) lists every family a text layer can use, bundled and installed, with its
styles, origin (`bundled`, `system`, `user`) and own-language name (`{"query":"gothic"}` filters
by name; `{"rescan":true}` first picks up fonts installed since launch). Pass a listed `family` and
one of its `styles` to `layer.setText {"font", "style"}`; `text.fontFeatures` says which OpenType
options a font draws with its own glyphs.

In expressions, `text.sourceText.style` / `getStyleAt(i, t)` read styles and the setters
(`setFontSize(v, start?, count?)`, `setFillColor`, `setText`, `setJustification`…) return a
styled document.

### Scripts and ScriptUI windows

Scripts that build ScriptUI windows publish them to the session; agents drive them like a user:

1. `scriptui.list` → `[{window, title, kind: dialog|palette|window|panel, script, modal, size}]`.
2. `scriptui.get {"window": id}` → the control tree (`type`, `name`, `text`, `value`, `checked`,
   `items`, `selection`, laid-out `bounds`, `handlers`…).
3. `scriptui.click {"widget": "ok"}` presses a button / toggles a checkbox / picks a radio button or
   tab; `scriptui.set {"widget": "#4", "value": "Shot_"}` types into edit text, moves a slider or
   picks a list item (index or text); `scriptui.close {"result": 2}` closes. Controls are addressed
   by id, `#id`, `properties.name` or text; `window` can be omitted when one window is open. Each
   returns the handler run's `{ok, output, error}`.

A dialog's `show()` waits for the user: the `script.run` / `file.runScript` reply carries
`"waiting": true`, and the script continues (its final output arrives in the reply of the click
that closes the dialog). File ▸ Scripts: `file.scripts.list`, `file.runScript {"name": …}`,
`file.installScript` / `file.installScriptUIPanel {"path": …}`, `window.scriptPanel {"name": …}`.

### Timeline: layer order, properties and shortcuts

* `layer.arrange {"layers": [...], "above": "Layer Name"}` moves layers to just above another
  one (what dragging Timeline rows does: the selected layers move together, one undo step);
  `to: front|forward|backward|back` and `index` still work.
* The reveal shortcuts are UI commands (`ui.menu.invoke` or the keys themselves): A Anchor Point,
  P Position, S Scale, R Rotation, T Opacity, M Mask Path, F Mask Feather, E Effects, L Audio
  Levels, U keyframed properties; pressed twice quickly AA Material Options, PP paint / Roto
  Brush / Puppet, SS selected properties, RR Time Remap, TT Mask Opacity, MM all mask
  properties, FF missing effects, EE Expressions, LL Waveform, UU everything changed from its
  default. Shift+key adds or removes a set; the same key again hides it; Ctrl/Cmd+` twirls the
  selected layers open or closed. With no layer selected they apply to every layer.
* `keys.toggleTransform {"layers"?: [...], "prop": "position"}` (Alt+Shift+A/P/S/R/T) adds or
  removes a keyframe at the current time on that Transform property of each layer, in one undo
  step (separated X/Y/Z Position; Orientation and X/Y/Z Rotation on 3D layers).
* Rename a layer with Enter (or double-click a name): the whole name is selected, Enter or a
  click elsewhere commits, Escape cancels; `layer.rename {layer, name}` does it directly.

### History, puppet recording, plug-ins

* `edit.history.list` lists every undo state as a tree (undoing then editing keeps the undone
  states as a branch); `edit.history.goto {"index": n}` (or `id`, or `steps`) jumps to any of
  them. MCP: the `history` tool.
* `puppet.recordPin {"layer": "#1", "pin": "Puppet Pin 1", "samples": [[t, x, y]…]}` records a
  drag (t = seconds since it began, layer space) into Position keys at the comp frame rate from the
  current time; `puppet.recordOptions {speed, smoothing, useDraftDeformation, showMesh}`.
* `puppet.selectPins {"layer": "#1", "pins": ["Puppet Pin 1"], "add"?, "toggle"?}` selects pins
  like the viewer's click / Shift-click (`pins: []` deselects); Edit ▸ Clear (Delete) then removes
  the selected pins, not their layer (`puppet.removePin {pins?}`). Advanced and Bend pins turn by
  their ring and scale by its square in the viewer (Shift: 15° / 5 % steps; automation ids
  `viewer.puppetPin.<uid>.rotate` / `.scale`), or `puppet.setPin {rotation, scale}`. A drag
  outside the art (or Alt-drag) marquee-selects pins; Edit ▸ Select All with a pin selected selects
  every pin of that kind; `puppet.recordPin {..., "pins": [...]}` records several pins moving
  together (⌘/Ctrl-drag one of several selected pins).
* Rigging pins: `paths.pointsFollowNulls {"layer": "#1", "pins"?: [...]}` gives each Position /
  Advanced pin a null that drives it (parent the nulls to each other to build limbs);
  `paths.nullsFollowPoints {..., "pins": [...]}` makes nulls that ride on pins (parent props to
  them). Without `pins` they use the selected pins, or every pin of a layer with no path.
* Follow-through (hair, cloth, tails): `puppet.follow {"leader": "Puppet Pin 1", "pins": [...],
  "delay": 0.1, "amount": 100, "cascade": true}` makes the pins trail the leader's motion (the
  k-th nearest by k × delay with `cascade`) through Position expressions; without `leader` /
  `pins` the first selected pin leads the other selected pins.
* `effect.plugins.load {"path": "x.wasm"}` / `effect.plugins.list`: WebAssembly effect plug-ins
  ([plugins.md](plugins.md)), then `effect.apply` by id like a built-in.

## CLI

Each invocation runs a headless engine with no window. It opens the demo project unless you pass
`--project F.ecproj`, a positional `*.ecproj` or `--empty`. Add `--json` for one compact JSON document
on stdout. Errors print `{"error": ...}` and exit with status 1; usage errors, such as an unknown
option, exit with status 2 before anything runs.

```sh
effectcraft-cli info --json
effectcraft-cli commands --filter keys
effectcraft-cli exec --list --schemas --json                     # every command with its params JSON Schema
effectcraft-cli exec comp.new --params '{"name":"Main","width":1280,"height":720}' --empty --save-as main.ecproj
effectcraft-cli exec layer.newSolid '{"color":"#3366ff"}' main.ecproj --save
effectcraft-cli props Main '#1' --project main.ecproj           # flat property list with paths
effectcraft-cli set Main '#1' transform/opacity 40 main.ecproj --save
effectcraft-cli set Main '#1' transform/position '[100,360]' --time 0 main.ecproj --save
effectcraft-cli get Main '#1' transform/position --time 0.5 main.ecproj --json
effectcraft-cli run main.ecproj comp.open '{"comp":"Main"}' time.set '{"time":1}' --json
effectcraft-cli render-frame main.ecproj --time 1 --max-side 640 --out f.png --json
effectcraft-cli exec layer.newNull --bridge 9877                 # same commands, against the live app
effectcraft-cli exec file.exportLottie '{"comp":"Main","path":"main.json","includeExpressions":true}' main.ecproj --json
effectcraft-cli exec file.importLottie '{"path":"anim.json"}' main.ecproj --save
```

Scripts written against After Effects' documented scripting API run with `script`:

```sh
effectcraft-cli script build.jsx --save-as main.ecproj     # empty project unless one is given
effectcraft-cli script --eval 'app.project.item(1).numLayers' main.ecproj --json
effectcraft-cli script tweak.jsx --bridge 9877              # against the live app
```

`writeLn`/`$.writeln`/`alert` output is printed, then the value of the last expression. A script
error exits with status 1 and `file:line:col: message`. Scripts may read files only in the
project's folder and may not write files or use the network unless the user turns on Preferences ▸
Scripting & Expressions ▸ Allow Scripts to Write Files and Access Network.

`file.exportLottie` returns `{path, bytes, warnings}`: the warnings list every feature Lottie
cannot express (most effects, cameras and lights, layer styles, audio, video footage…), so an
agent can check what a player will not show. A `.lottie` path writes a dotLottie archive.
`file.importLottie` returns `{comp, items, warnings}` and opens the new composition.

Premiere Pro interop goes through timeline interchange (MCP: the `execute_command` tool; control channel: `engine.execute`
with the same ids):

```sh
effectcraft-cli exec file.importTimeline '{"path":"edit.xml"}' main.ecproj --save      # FCP7 XML / .fcpxml / .otio / .edl / .aaf / .omf
effectcraft-cli exec file.exportTimeline '{"comp":"Main","path":"Main.xml"}' main.ecproj --json
effectcraft-cli exec file.exportTimeline '{"comp":"Main","path":"Main.otio","prerender":"none"}' main.ecproj
```

`file.importTimeline` returns `{format, folder, comps, allComps, items, missing, warnings}`
(`missing` lists media imported as placeholders). `file.exportTimeline` writes Final Cut Pro XML
(`.xml`, which Premiere Pro opens with File ▸ Import) unless `format` or the extension says
`fcpxml`, `otio`, `edl`, `aaf` or `omf`; `prerender` (`unsupported` by default, `all`, `none`) controls which
layers are rendered to ProRes 4444 movies next to the document. It returns `{path, format,
sequences, videoTracks, audioTracks, clips, prerendered, warnings}`. Native `.prproj` files are
not read or written.

`<comp>` is an id or name, or `-` for the active comp. `<value>` is JSON (`50`, `[960,540]`,
`"#ff0000"`) or a bare string.

## Seeing the UI

To work on the UI, start the app with `cargo run -p effectcraft -- --control 9877` (add `--demo` to
open the demo project; without it the app starts with an empty project) and use MCP bridge
mode or the raw control channel. A good loop is: `ui_elements` to find an id, `ui_click` or `ui_drag`
to act, then `screenshot {"panel":"Timeline"}` to check the result. `render_frame` shows the
composition itself at any zoom.