88 lines
5.3 KiB
Markdown
88 lines
5.3 KiB
Markdown
# Control protocol
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The desktop app exposes a control channel for agents, tests and the MCP bridge:
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```sh
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effectcraft --control 9877 # or EFFECTCRAFT_CONTROL_PORT=9877
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```
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- **Transport:** TCP on `127.0.0.1` only, one JSON object per line in each direction. Connections are
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persistent; requests on one connection are answered in order.
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- **Request:** `{"id": 1, "method": "engine.execute", "params": {...}}` (`id` is echoed back, `params`
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defaults to `{}`).
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- **Reply:** `{"id": 1, "ok": true, "result": ...}` or `{"id": 1, "ok": false, "error": "message"}`.
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- Requests run on the UI thread between frames. Input methods (`ui.click`, `ui.key` and similar)
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reply after the synthetic input has been processed. Methods that need an element that isn't drawn
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yet are retried for a few frames. A request times out after 60 s.
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Quick test:
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```sh
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printf '{"id":1,"method":"engine.execute","params":{"command":"comp.new","params":{"name":"A"}}}\n' | nc 127.0.0.1 9877
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```
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## Engine
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| Method | Params | Result |
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| `engine.execute` | `{command, params?}` | The command's result. Every engine command (`effectcraft-cli commands`) runs exactly as it does headless, so it never opens a dialog: `comp.new {}` creates a default comp. UI-only ids (`tool.*`, `view.*`, `window.*`, `playback.*`, `timeline.*`, `app.*`) fall through to the menu dispatcher. Unknown top-level params are rejected, and the error lists the accepted keys. |
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| `ui.menu.invoke` | `{id, params?}` | Like a menu click: commands with empty params may open their dialog (New Composition, Solid Settings, file pickers). |
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| `engine.commands` | `{filter?, enabledOnly?}` | `[{id, label, menu, shortcut, params, enabled, why}]` |
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| `ui.menu.list` | `{}` | The menu tree with enablement. |
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| `render.frame` | `{comp?, time?, max_side?, path?, base64?}` | Renders a comp frame through the session, independent of the viewer zoom or resolution. `comp` is an id or name (default: the active comp), `time` is in comp seconds (default: the CTI), `max_side` caps the longest side (0 = full size). Writes a PNG to `path` (default: a temp file) and returns `{comp, time, width, height, path}`. With `base64: true` it returns `{…, png: "<base64>"}` and writes no file. |
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Useful query commands for `engine.execute` (they aren't journaled or undoable): `project.summary`,
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`comp.info {comp?}`, `layer.tree {layer, comp?, depth?, time?}` (every node has a `path`),
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`prop.get {layer, path, comp?, time?}`, `editor.state`, `command.list {filter?, enabledOnly?}`.
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## UI state
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| Method | Params | Result |
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| `ui.inspect` | `{}` | Window size, pixels per point, fps, serialized `UiState`, playback, time, active comp, selection, open dialog, last render ms. |
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| `ui.elements` | `{prefix?}` | `[{id, label, rect: [x, y, w, h]}]`: the widgets drawn in the last frame, in points. |
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| `ui.set` | `{tool?, workspace?, theme?, focused?, viewer?, timeline?, menuBar?, home?}` | `viewer: {zoom (null = fit), res: Full\|Half\|Third\|Quarter\|Auto, pan: [x,y], grid, rulers, safeMargins, transparencyGrid}`; `timeline: {pps (null = fit), start, graphEditor, showModes, openLayers: [ids], openGroups: [uids]}`. |
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| `ui.panel.show` / `ui.panel.close` | `{panel}` | Panels: `Project`, `Composition`, `Timeline`, `EffectControls`, `EffectsPresets`, `Info`, `Preview`, `Character`, `Paragraph`, `Align` and others. |
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| `ui.playback` | `{action: play\|stop\|toggle}` | `{playing, time}` |
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| `ui.resize` | `{width, height}` | Resizes the window (points). |
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| `ui.focus` | `{}` | Activates the window and takes keyboard focus. Agents normally avoid this, because the app is started without stealing focus. |
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| `app.quit` | `{}` | Closes the app. |
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## Input
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Points are logical window coordinates. A target is `{id}` (the element's centre; add `fx`/`fy` between
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0 and 1 to pick a spot inside it) or `{x, y}`. `modifiers` is `{shift, alt, command, ctrl}`, where
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`command` is ⌘ on macOS and Ctrl elsewhere.
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| Method | Params |
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| `ui.click` | `{id \| x,y, button?: left\|right\|middle, count?, modifiers?}` |
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| `ui.move` | `{id \| x,y}` |
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| `ui.drag` | `{from: target, to: target, steps? (12), modifiers?}`: press, move, release |
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| `ui.scroll` | `{id \| x,y, dx, dy}` |
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| `ui.key` | `{key}`, for example `Space`, `F9`, `Cmd+Z`, `Cmd+Shift+Z`, `PageDown`, `Escape` |
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| `ui.type` | `{text}`: text input into the focused field |
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## Locating things
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| Method | Params | Result |
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| `ui.viewer.locate` | `{x, y}` (comp pixels) | `{x, y}` window point |
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| `ui.viewer.hit` | `{id \| x,y}` (window point) | `{x, y}` comp pixel |
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| `ui.timeline.locate` | `{layer (id), time?}` | `{x, y}` window point on the layer bar |
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## Screenshots
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| Method | Params | Result |
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| `ui.screenshot` | `{path?, panel?, id?}` | `{path, width, height}`: a PNG of the window, or cropped to one panel or element. |
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Element ids are stable, for example `tools.Selection`, `panel.Timeline`, `panel.tab.EffectControls`,
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`header.workspace.Animation`, `project.item.<id>`, `viewer.comp`, `viewer.handle.<layer>.<i>`,
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`timeline.layer.<id>.bar`, `timeline.layer.<id>.twirl`, `timeline.prop.<uid>.stopwatch`,
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`timeline.key.<uid>.<frame>`, `timeline.cti`, `effectControls.prop.<uid>.value` and
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`effects.item.<name>`. Use `ui.elements` to see what is on screen.
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The MCP server's bridge mode (`effectcraft-cli mcp --bridge 9877`) is a thin client of this protocol;
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see [agents.md](agents.md).
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