438 lines
18 KiB
Markdown
438 lines
18 KiB
Markdown
# `open-pencil eval` — Figma-like Plugin API for Headless Scripting
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## Overview
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`bun open-pencil eval <file> --code '<js>'` executes JavaScript against a `.fig` file with a Figma-compatible `figma` global object. This enables headless scripting, batch operations, AI tool execution, and testing — all without the GUI.
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The `figma` object mirrors Figma's Plugin API surface as closely as possible, so existing Figma plugin knowledge and code snippets transfer directly.
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```bash
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# Create a frame, set auto-layout, add children
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bun open-pencil eval design.fig --code '
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const frame = figma.createFrame()
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frame.name = "Card"
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frame.resize(300, 200)
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frame.layoutMode = "VERTICAL"
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frame.itemSpacing = 12
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frame.paddingTop = frame.paddingBottom = 16
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frame.paddingLeft = frame.paddingRight = 16
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frame.fills = [{ type: "SOLID", color: { r: 1, g: 1, b: 1 } }]
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const title = figma.createText()
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title.characters = "Hello World"
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title.fontSize = 24
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frame.appendChild(title)
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return { id: frame.id, name: frame.name }
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'
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# Query nodes
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bun open-pencil eval design.fig --code '
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const buttons = figma.currentPage.findAll(n => n.type === "FRAME" && n.name.includes("Button"))
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return buttons.map(b => ({ id: b.id, name: b.name, w: b.width, h: b.height }))
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'
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# Read from stdin (for multiline scripts / piping)
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cat transform.js | bun open-pencil eval design.fig --stdin
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# Write changes back
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bun open-pencil eval design.fig --code '...' --write
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bun open-pencil eval design.fig --code '...' -o modified.fig
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```
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## Architecture
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```
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┌──────────────────────────────────────────────────────┐
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│ CLI: `open-pencil eval <file> --code '...'` │
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│ ↓ │
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│ loadDocument(file) → SceneGraph │
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│ ↓ │
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│ FigmaAPI(sceneGraph) → `figma` proxy object │
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│ ↓ │
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│ AsyncFunction('figma', wrappedCode)(figmaProxy) │
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│ ↓ │
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│ print result as JSON / agentfmt │
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│ optionally: saveDocument(file) if --write │
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└──────────────────────────────────────────────────────┘
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```
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### Key classes
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| Class | Location | Role |
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|-------|----------|------|
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| `FigmaAPI` | `packages/core/src/figma-api.ts` | Proxy object implementing `figma.*` methods against `SceneGraph` |
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| `FigmaNode` | `packages/core/src/figma-api.ts` | Proxy wrapping `SceneNode` with Figma-style property access (`.fills`, `.resize()`, `.appendChild()`, etc.) |
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| `eval` command | `packages/cli/src/commands/eval.ts` | CLI command that loads doc, creates API, executes code |
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### Why in `@open-pencil/core`?
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The `FigmaAPI` class lives in core (not CLI) because:
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- **AI tools reuse it** — the chat panel's `render` tool can execute JSX through the same API
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- **Test scripts** — unit tests can use the API to set up fixtures
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- **No DOM deps** — runs headless in Bun, no browser APIs needed
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## `FigmaAPI` — Phased Implementation
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### Phase 1: Core (MVP for eval command)
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These cover ~80% of real plugin scripts:
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#### Document & Page
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| Figma API | Our implementation | Notes |
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|-----------|--------------------|-------|
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| `figma.root` | Getter → proxy for root node | `.children` returns page proxies |
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| `figma.currentPage` | Getter/setter → first page by default | Settable to any page proxy |
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| `figma.currentPage.selection` | Get/set → tracked selection array | |
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| `figma.getNodeById(id)` | `graph.getNode(id)` wrapped in proxy | Sync, like Figma's deprecated version |
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#### Node Creation
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| Figma API | Maps to |
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|-----------|---------|
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| `figma.createFrame()` | `graph.createNode('FRAME', currentPageId)` |
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| `figma.createRectangle()` | `graph.createNode('RECTANGLE', ...)` |
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| `figma.createEllipse()` | `graph.createNode('ELLIPSE', ...)` |
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| `figma.createText()` | `graph.createNode('TEXT', ...)` |
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| `figma.createLine()` | `graph.createNode('LINE', ...)` |
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| `figma.createPolygon()` | `graph.createNode('POLYGON', ...)` |
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| `figma.createStar()` | `graph.createNode('STAR', ...)` |
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| `figma.createComponent()` | `graph.createNode('COMPONENT', ...)` |
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| `figma.createPage()` | `graph.addPage(name)` |
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| `figma.createSection()` | `graph.createNode('SECTION', ...)` |
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#### Node Properties (via `FigmaNode` proxy)
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Read/write on any node proxy. Property access maps to `SceneNode` fields:
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```ts
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// Geometry
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node.x, node.y // direct
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node.width, node.height // read-only, use node.resize(w, h)
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node.rotation // direct
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node.resize(w, h) // updates width + height
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node.resizeWithoutConstraints(w, h) // same (no constraint engine yet)
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// Visual
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node.fills // get/set Fill[]
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node.strokes // get/set Stroke[]
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node.effects // get/set Effect[]
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node.opacity // get/set number
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node.visible // get/set boolean
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node.locked // get/set boolean
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node.blendMode // get/set BlendMode
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node.clipsContent // get/set boolean
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// Corner radius
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node.cornerRadius // get/set (number or figma.mixed)
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node.topLeftRadius // get/set
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node.topRightRadius // get/set
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node.bottomLeftRadius // get/set
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node.bottomRightRadius // get/set
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node.cornerSmoothing // get/set
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// Identity
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node.id // read-only
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node.name // get/set
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node.type // read-only
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node.parent // read-only → FigmaNode | null
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node.removed // read-only boolean
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```
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#### Tree Operations
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```ts
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node.children // read-only FigmaNode[]
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node.appendChild(child) // reparent to end
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node.insertChild(index, child) // reparent at index
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node.remove() // graph.deleteNode(id)
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// Traversal
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node.findAll(callback?) // recursive find
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node.findOne(callback) // first match
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node.findChild(callback) // direct children only
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node.findChildren(callback?) // direct children only
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```
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#### Auto-layout
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```ts
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node.layoutMode // 'NONE' | 'HORIZONTAL' | 'VERTICAL'
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node.primaryAxisAlignItems // 'MIN' | 'CENTER' | 'MAX' | 'SPACE_BETWEEN'
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node.counterAxisAlignItems // 'MIN' | 'CENTER' | 'MAX' | 'BASELINE'
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node.itemSpacing // number
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node.counterAxisSpacing // number | null
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node.paddingTop / Right / Bottom / Left // number
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node.layoutWrap // 'NO_WRAP' | 'WRAP'
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// Child sizing
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node.layoutPositioning // 'AUTO' | 'ABSOLUTE'
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node.layoutGrow // 0 | 1
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node.layoutSizingHorizontal // 'FIXED' | 'HUG' | 'FILL'
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node.layoutSizingVertical // 'FIXED' | 'HUG' | 'FILL'
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```
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#### Text
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```ts
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node.characters // get/set (maps to node.text)
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node.fontSize // get/set
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node.fontName // get/set { family, style }
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node.fontWeight // get/set
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node.textAlignHorizontal // get/set
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node.textAlignVertical // get/set
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node.textAutoResize // get/set
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node.letterSpacing // get/set
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node.lineHeight // get/set
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node.maxLines // get/set
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node.textCase // get/set
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node.textDecoration // get/set
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```
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#### Stroke details
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```ts
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node.strokeWeight // get/set (maps to strokes[0].weight)
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node.strokeAlign // get/set (maps to strokes[0].align)
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node.dashPattern // get/set
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```
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#### Misc
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```ts
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figma.mixed // Symbol sentinel for mixed values
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figma.group(nodes, parent) // creates GROUP with given children
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figma.ungroup(node) // ungroups, reparents children
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figma.flatten(nodes) // NOT IMPLEMENTED YET — returns first node
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```
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#### Export
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```ts
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node.exportAsync(settings?) // only works if CanvasKit is loaded
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// settings: { format: 'PNG'|'JPG'|'SVG', constraint? }
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```
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### Phase 2: Components & Instances
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| API | Maps to |
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|-----|---------|
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| `figma.createComponent()` | `graph.createNode('COMPONENT', ...)` |
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| `figma.createComponentFromNode(node)` | Convert existing frame to component |
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| `figma.combineAsVariants(components, parent)` | Create COMPONENT_SET |
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| Node: `node.createInstance()` | `graph.createInstance(componentId, parentId)` |
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| Node: `node.detachInstance()` | `graph.detachInstance(id)` |
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| `figma.getNodeById(id).mainComponent` | `graph.getMainComponent(id)` |
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### Phase 3: Variables
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| API | Maps to |
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|-----|---------|
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| `figma.variables.getLocalVariables(type?)` | `graph.variables` filtered |
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| `figma.variables.getLocalVariableCollections()` | `graph.variableCollections` |
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| `figma.variables.createVariable(name, collection, type)` | `graph.addVariable(...)` |
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| `figma.variables.createVariableCollection(name)` | `graph.addCollection(...)` |
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| `figma.variables.getVariableById(id)` | `graph.variables.get(id)` |
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| `node.setBoundVariable(field, variable)` | `graph.bindVariable(...)` |
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| `node.boundVariables` | getter from SceneNode |
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### Phase 4: Styles & Advanced
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| API | Notes |
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|-----|-------|
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| `figma.createPaintStyle()` | Requires style storage in SceneGraph |
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| `figma.createTextStyle()` | Requires style storage in SceneGraph |
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| `figma.createEffectStyle()` | Requires style storage in SceneGraph |
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| `figma.loadFontAsync(fontName)` | No-op (we don't have font loading constraints) |
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| `figma.listAvailableFontsAsync()` | Return system fonts if available |
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| Boolean operations (`union`, `subtract`, `intersect`, `exclude`) | Requires path boolean engine |
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| `figma.createNodeFromJSXAsync(jsx)` | Port figma-use's JSX renderer |
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## `FigmaNode` Proxy Design
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The proxy wraps a `SceneNode` and translates Figma property names to our internal names. Key mappings:
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```ts
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const PROPERTY_MAP: Record<string, string> = {
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// Figma name → SceneNode field name (only where they differ)
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'characters': 'text',
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'strokeWeight': → computed from strokes[0].weight,
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'strokeAlign': → computed from strokes[0].align,
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'fontName': → computed from { family: fontFamily, style: ... },
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'primaryAxisAlignItems': 'primaryAxisAlign',
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'counterAxisAlignItems': 'counterAxisAlign',
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'primaryAxisSizingMode': 'primaryAxisSizing', // value mapping: 'AUTO' → 'HUG', 'FIXED' → 'FIXED'
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'counterAxisSizingMode': 'counterAxisSizing',
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'layoutSizingHorizontal': → computed from primaryAxisSizing / counterAxisSizing depending on layoutMode
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'layoutSizingVertical': → computed
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}
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```
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Methods on the proxy:
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```ts
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class FigmaNode {
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// The proxy is created via: new Proxy(target, handler)
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// where handler.get intercepts property reads and handler.set intercepts writes
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resize(width: number, height: number): void
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resizeWithoutConstraints(width: number, height: number): void
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remove(): void
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appendChild(child: FigmaNode): void
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insertChild(index: number, child: FigmaNode): void
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findAll(callback?: (node: FigmaNode) => boolean): FigmaNode[]
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findOne(callback: (node: FigmaNode) => boolean): FigmaNode | null
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findChild(callback: (node: FigmaNode) => boolean): FigmaNode | null
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findChildren(callback?: (node: FigmaNode) => boolean): FigmaNode[]
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exportAsync(settings?: ExportSettings): Promise<Uint8Array>
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// Components (Phase 2)
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createInstance(): FigmaNode
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detachInstance(): void
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get mainComponent(): FigmaNode | null
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}
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```
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## CLI Command
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```
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bun open-pencil eval <file> [options]
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Arguments:
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file .fig file to operate on
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Options:
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--code, -c JavaScript code to execute (has access to `figma` global)
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--stdin Read code from stdin instead of --code
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--write, -w Write changes back to the input file
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-o, --output Write to a different file
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--json Output result as JSON (default for non-TTY)
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--quiet, -q Suppress output, only write file
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```
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### Execution model
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1. Load `.fig` → `SceneGraph`
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2. Create `FigmaAPI(graph)` → `figma` proxy
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3. Wrap user code in async function: `return (async () => { <code> })()`
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4. Execute with `figma` as sole argument
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5. Print return value (JSON or agentfmt)
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6. If `--write` or `-o`: serialize `SceneGraph` back to `.fig`
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### Return value formatting
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- `undefined` / `void` → no output
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- Primitives → printed directly
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- Objects/arrays → `JSON.stringify(result, null, 2)` or agentfmt tables
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- `FigmaNode` → serialized as `{ id, type, name, x, y, width, height, fills, ... }`
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- Arrays of `FigmaNode` → serialized as list
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## Shared with AI Tools
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The `FigmaAPI` class is the **same API surface** that AI tools use. Currently `src/ai/tools.ts` calls `store.createShape()`, `store.updateNodeWithUndo()`, etc. — these should be refactored to go through `FigmaAPI`:
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```ts
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// Before (current AI tools)
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execute: async ({ type, x, y, width, height }) => {
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const id = store.createShape(type, x, y, width, height)
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return { id }
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}
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// After (using FigmaAPI)
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execute: async ({ type, x, y, width, height }) => {
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const frame = figma.createFrame()
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frame.resize(width, height)
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frame.x = x
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frame.y = y
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return { id: frame.id }
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}
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```
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This ensures CLI scripts and AI tools behave identically.
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## File Layout
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```
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packages/core/src/
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figma-api.ts # FigmaAPI class + FigmaNode proxy (Phase 1–4)
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figma-api.test.ts # Unit tests against headless SceneGraph
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packages/cli/src/commands/
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eval.ts # CLI command
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packages/cli/src/commands/eval.test.ts # Integration tests
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```
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## Test Plan
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### Unit tests (`packages/core/src/figma-api.test.ts`)
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1. **Node creation** — each `createX()` creates correct type, added to current page
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2. **Property access** — `.fills`, `.x`, `.width`, `.name`, `.characters` read/write correctly
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3. **Resize** — `.resize(w, h)` updates width/height
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4. **Tree operations** — `.appendChild()`, `.insertChild()`, `.remove()`, `.parent`, `.children`
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5. **Traversal** — `.findAll()`, `.findOne()`, `.findChild()`, `.findChildren()` with callbacks
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6. **Auto-layout** — `.layoutMode`, `.itemSpacing`, `.paddingTop`, etc.
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7. **Text** — `.characters` maps to `.text`, `.fontName` maps to `{ family, style }`
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8. **Mixed values** — `.cornerRadius` returns `figma.mixed` when corners differ
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9. **Selection** — `figma.currentPage.selection` get/set
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10. **Page switching** — `figma.currentPage = page2` works
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11. **Group/ungroup** — `figma.group()` creates group, `figma.ungroup()` dissolves it
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12. **Clone** — node creation produces independent copies
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### CLI integration tests (`packages/cli/src/commands/eval.test.ts`)
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1. **Basic eval** — `eval test.fig --code 'return figma.currentPage.name'` → page name
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2. **Create + read** — create a frame, return its properties
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3. **Query nodes** — `findAll` returns correct nodes
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4. **Write back** — `--write` saves changes, reloading shows them
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5. **Stdin** — `echo 'return 42' | bun open-pencil eval test.fig --stdin` → `42`
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6. **JSON output** — `--json` returns valid JSON
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7. **Error handling** — syntax errors, runtime errors reported cleanly
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## Implementation Order
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1. **`FigmaNode` proxy** — property mapping, `.resize()`, `.remove()`, tree methods
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2. **`FigmaAPI` class** — `createFrame/Rectangle/...`, `.root`, `.currentPage`, `.getNodeById()`, `.mixed`, `.group()`
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3. **CLI `eval` command** — argument parsing, code wrapping, output formatting
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4. **Unit tests** — all 12 test groups above
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5. **CLI integration tests** — all 7 test groups above
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6. **Wire to AI tools** — refactor `src/ai/tools.ts` to use `FigmaAPI` where possible
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7. **Phase 2** — components & instances
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8. **Phase 3** — variables
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9. **Phase 4** — styles, boolean ops, JSX renderer
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## Property Mapping Reference
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| Figma Property | SceneNode Field | Type | Notes |
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|---------------|-----------------|------|-------|
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| `characters` | `text` | `string` | |
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| `fontName` | `fontFamily` + `fontWeight` + `italic` | `{ family, style }` | Computed: `style` = "Bold Italic" etc. |
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| `strokeWeight` | `strokes[0].weight` | `number` | Computed |
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| `strokeAlign` | `strokes[0].align` | `string` | Computed |
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| `primaryAxisAlignItems` | `primaryAxisAlign` | `string` | |
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| `counterAxisAlignItems` | `counterAxisAlign` | `string` | |
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| `layoutSizingHorizontal` | `primaryAxisSizing` or `counterAxisSizing` | `string` | Depends on `layoutMode` |
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| `layoutSizingVertical` | (opposite of horizontal) | `string` | |
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| `absoluteTransform` | computed from `x`, `y`, `rotation` | `Transform` | Read-only |
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| `absoluteBoundingBox` | `getAbsoluteBounds(id)` | `Rect` | Read-only |
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| All others | Same name | Same type | Direct passthrough |
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## Open Questions
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1. **Font loading**: `figma.loadFontAsync()` — should it be a no-op (we don't have font gating) or should we track loaded fonts?
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→ **Decision: No-op that returns resolved Promise.** We don't gate text editing on font loading.
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2. **Export in headless mode**: `node.exportAsync()` requires CanvasKit. Should eval load CanvasKit?
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→ **Decision: Optional.** If CanvasKit is available (via `--with-canvaskit` flag or env), enable export. Otherwise, throw "Export requires CanvasKit" error.
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3. **`figma.mixed` symbol**: Should we use the actual Figma symbol or our own?
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→ **Decision: Our own `Symbol('mixed')`.** Exposed as `figma.mixed`.
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4. **Undo**: `figma.commitUndo()` / `figma.triggerUndo()` — relevant in headless?
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→ **Decision: No-op in CLI.** Undo only matters in the live editor. The AI tools can add undo support separately via EditorStore.
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5. **Write format**: Should `--write` produce `.fig` (Kiwi binary) or also support `.json`?
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→ **Decision: `.fig` only for now.** JSON export is a separate feature.
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