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Danila Poyarkov 19d01f0835
fix(harness): start Pi sessions with MCP tools under Node (#897)
* fix(harness): start Pi sessions with MCP tools under Node

The desktop app always gives Pi OpenPencil's MCP server, and the
published companion failed every such session:

- @ai-sdk/harness-pi imports pi-mcp-adapter, which publishes only
  TypeScript sources, and Node refuses to strip types under
  node_modules. A module load hook now strips them for TypeScript
  dependencies only; Bun runs them as is. (vercel/ai#22040)
- pi-mcp-adapter imports @earendil-works/pi-tui but declares it as an
  optional peer, so npm leaves it out. The companion depends on it at
  the version pi-coding-agent uses, and a test keeps the two in step.
  (nicobailon/pi-mcp-adapter#805)
- Pi reports live-process resume, yet the service handed it state
  saved by an earlier session, and the just-bash sandbox cannot resume,
  so every later session with that ID failed. Live-process backends now
  start fresh and drop saved state.

Pi also installs the packages from a person's Pi settings with npm on
every session, writing npm's output to the companion's stdout. The
companion now keeps the real stdout for protocol messages, sends other
writes to stderr, and quiets npm on success. The app logs companion
stderr as diagnostics, since failures arrive as protocol errors.

* fix(harness): reject another backend's state before dropping it

loadResumeState removed saved state for a live-process backend before
createSession checked which backend owned it, so state saved by another
backend was lost instead of rejected. Ownership is checked first, and
only state that belongs to the live-process backend is dropped.
2026-10-05 17:21:50 +00:00
.claude ci: keep AI disclosure out of co-author credits 2026-09-15 23:12:44 +03:00
.devcontainer refactor: rename @open-pencil/codegen to @open-pencil/emit (#822) 2026-10-04 11:22:20 +00:00
.github fix(ci): install the review guidance tool's dependencies (#891) 2026-10-05 06:24:03 +00:00
.storybook fix(vue): start CanvasKit once CanvasSurface provides the canvas (#823) 2026-10-02 00:23:49 +04:00
.vscode
assets/brand build(tools): group tools by role and gate them like the rest of the repo (#791) 2026-09-30 05:00:31 +04:00
desktop feat: create, fill, and edit slots (#862) 2026-10-04 17:02:28 +00:00
lint build(tools): group tools by role and gate them like the rest of the repo (#791) 2026-09-30 05:00:31 +04:00
packages fix(harness): start Pi sessions with MCP tools under Node (#897) 2026-10-05 17:21:50 +00:00
public feat: refresh branding with generated platform icons (#707) 2026-09-16 11:54:07 +03:00
skills/open-pencil fix: share CSS value parsing between dom-css and design JSX (#910) 2026-10-05 17:02:43 +00:00
src fix(harness): start Pi sessions with MCP tools under Node (#897) 2026-10-05 17:21:50 +00:00
tests fix: share CSS value parsing between dom-css and design JSX (#910) 2026-10-05 17:02:43 +00:00
tools test: run each heavy unit test file in its own process (#899) 2026-10-05 14:13:53 +00:00
vite feat(lint): suggest group-to-frame and hidden-layer fixes; keep canvas edits in code previews (#870) 2026-10-04 12:46:06 +00:00
.coderabbit.yaml chore: hide review status chatter and test generation prompts 2026-09-15 21:43:04 +03:00
.gitattributes build: merge CHANGELOG.md entries instead of conflicting (#905) 2026-10-05 12:56:22 +00:00
.gitignore build(tools): group tools by role and gate them like the rest of the repo (#791) 2026-09-30 05:00:31 +04:00
.gitleaks.toml
.lfsconfig
.oxfmtrc.json
AGENTS.md fix: lay out fill text and repeat() grid tracks (#866) 2026-10-05 14:06:07 +00:00
bun.lock fix(harness): start Pi sessions with MCP tools under Node (#897) 2026-10-05 17:21:50 +00:00
bunfig.toml
CHANGELOG.md fix(harness): start Pi sessions with MCP tools under Node (#897) 2026-10-05 17:21:50 +00:00
commitlint.config.ts build(tools): group tools by role and gate them like the rest of the repo (#791) 2026-09-30 05:00:31 +04:00
CONTRIBUTING.md docs: describe rebasing and merging stacked pull requests (#869) 2026-10-04 10:17:30 +00:00
index.html fix: explain unsupported browsers instead of a blank window (#745) 2026-09-22 14:40:59 +04:00
knip.json
LICENSE docs: acknowledge OpenPencil contributors in license 2026-08-31 09:11:10 +03:00
oxlint.json chore: prefer es-toolkit helpers and lint the mechanical cases (#898) 2026-10-05 09:34:00 +00:00
package.json test: typecheck the test suites and fix what that found (#896) 2026-10-05 12:42:38 +00:00
playwright.config.ts chore: merge master into live-editor-regressions 2026-09-16 00:14:31 +03:00
portless.json
README.md docs: trim the README CLI section and align its examples (#885) 2026-10-04 16:38:28 +00:00
SECURITY.md
steiger.config.ts build(tools): group tools by role and gate them like the rest of the repo (#791) 2026-09-30 05:00:31 +04:00
tsconfig.json test: typecheck the test suites and fix what that found (#896) 2026-10-05 12:42:38 +00:00
tsconfig.node.json ci: validate PR commits and streamline package verification 2026-09-15 20:51:33 +03:00
tsconfig.tests.json test: typecheck the test suites and fix what that found (#896) 2026-10-05 12:42:38 +00:00
vite.config.ts feat: preview streamed JSX on the canvas (#692) 2026-10-01 10:52:36 +04:00
wdio.conf.ts test(native): cover the desktop MCP server lifecycle (#723) 2026-09-18 11:42:55 +03:00

OpenPencil

MIT license npm Discord GitHub Discussions

Open-source design editor. Opens .fig and .pen design files, includes built-in AI, and ships as a programmable toolkit with a headless Vue SDK for building custom editors.

Status: Active development. Usable today, with some rough edges as features evolve.

Try it online → · Download · Documentation · Roadmap · llms.txt

OpenPencil

Installation

macOS (Homebrew):

brew install --cask openpencil

Or download from the releases page, or use the web app — no install needed.

Requires macOS 13 or later with current Safari updates, Windows 10 or later, or Linux with WebKitGTK 2.40+; the web app needs Chrome 111, Edge 111, Firefox 128, or Safari 16.4 or later. See system requirements.

What it does

  • Opens .fig and .pen files — read and write native Figma files, open supported Pencil documents from the app or OS file browser, copy & paste nodes between apps
  • AI builds designs — describe what you want in chat, 100+ tools create and modify nodes. Connect OpenRouter, Anthropic, OpenAI, Google AI, DeepSeek, Z.ai, MiniMax, or compatible endpoints
  • Fully programmable — headless CLI, XPath queries, Figma Plugin API via eval, MCP server for AI agents, and desktop agent integrations for Claude Code, Codex, and Gemini CLI
  • Lint, convert, and extract tokens — inspect documents, lint naming/layout/accessibility, convert between supported formats, analyze colors/typography/spacing/clusters, and extract design tokens
  • Components and variants — create reusable components, group variants into component sets, insert local assets as instances, and switch variants from the inspector
  • Image vectorization — convert image layers into editable vector layers with Recraft or fal.ai
  • Design-to-code export — export selections as JSX/Tailwind, generate token outputs, and map designs into component-oriented code workflows
  • Vue SDK for custom editors — headless components and composables for embedding OpenPencil into other apps or building workflow-specific editing surfaces. Read the SDK docs →
  • Real-time collaboration — P2P via WebRTC, no server, no account. Cursors, presence, follow mode
  • Auto layout & CSS Grid — flex and grid layout via Yoga WASM, with gap, padding, alignment, track sizing
  • ~15 MB desktop app — Tauri v2 for macOS, Windows, Linux. Also runs in the browser as a PWA

CLI

npm install -g @open-pencil/cli
# or: bun add -g @open-pencil/cli

Inspect design files

Browse node trees, search by name or type, dig into properties — all without opening the editor:

openpencil tree design.fig
openpencil find design.pen --type TEXT
openpencil node design.fig --id 1:23
openpencil info design.fig
[0] [page] "Getting started" (0:46566)
  [0] [section] "" (0:46567)
    [0] [frame] "Body" (0:46568)
      [0] [frame] "Introduction" (0:46569)
        [0] [frame] "Introduction Card" (0:46570)
          [0] [frame] "Guidance" (0:46571)

Query with XPath

Find nodes by type, attributes, and structure:

openpencil query design.fig "//FRAME[@width < 300]"  # Frames under 300px
openpencil query design.fig "//SECTION//TEXT"        # Text inside sections

Export, convert, and import

Render to PNG, JPG, WEBP, SVG, PDF, PPTX, HTML, JSX, Storybook stories, or .fig, convert between document formats, and turn HTML/CSS into editable layers:

openpencil export design.fig                  # PNG
openpencil export design.fig -f jpg -s 2      # JPG at 2x
openpencil export design.fig -f tailwind-jsx  # Tailwind JSX
openpencil export design.fig -f storybook     # Storybook stories per component
openpencil convert design.pen design.fig      # Between document formats
openpencil import card.html --css card.css    # HTML/CSS → editable .fig

Lint and analyze

Catch naming, layout, and accessibility issues, and audit a design system's real palette, type scale, spacing, and repeated components:

openpencil lint design.fig --preset strict  # Naming, layout, accessibility
openpencil analyze colors design.fig        # Also typography, spacing, clusters
openpencil variables design.fig             # Variables and collections
#1d1b20  ██████████████████████████████ 17155×
#49454f  ██████████████████████████████ 9814×
#ffffff  ██████████████████████████████ 8620×
#6750a4  ██████████████████████████████ 3967×

Script with the Figma Plugin API

eval runs JavaScript against the document with Figma's Plugin API; -w writes the result back:

openpencil eval design.fig -c "figma.currentPage.selection.forEach(n => n.opacity = 0.5)" -w

Control the running app

Omit the file argument and the CLI works on the document open in the editor:

openpencil tree                                 # Inspect the live document
openpencil documents list                       # Also open, new, save, close, activate
openpencil tool call get_selection              # Run any MCP tool
openpencil undo                                 # Undo the newest automation change
openpencil settings set appearance.theme light  # Change editor settings

Every command supports --json. See the CLI reference for all commands and options.

AI & MCP

Built-in chat

Press ⌘J (CtrlJ on Windows and Linux) to open the AI assistant. It has 100+ tools that can create shapes, set fills and strokes, manage auto-layout, work with components and variables, run boolean operations, analyze design tokens, and export assets. Bring your own API key for OpenRouter, Anthropic, OpenAI, Google AI, DeepSeek, Z.ai, MiniMax, or compatible endpoints. No backend, no account.

Not every provider works in the browser, and not every model streams tool calls correctly. See BYOK provider & model compatibility for measured results — contributions welcome.

Coding agents (desktop)

Use Claude Code, Codex, or Gemini CLI directly in the chat panel. The agent connects to the editor's MCP server and uses all 100+ design tools. Requires the desktop app and the agent CLI installed locally.

Pi works too: install @open-pencil/harness globally, then add a Pi model profile in Settings → AI & agents.

Setup (Claude Code):

  1. Install the ACP adapter: npm install -g @agentclientprotocol/claude-agent-acp
  2. Add MCP permission to ~/.claude/settings.json:
    {
      "permissions": {
        "allow": ["mcp__open-pencil__*"]
      }
    }
    
  3. Open the desktop app → ⌘J → select Claude Code from the provider dropdown

MCP server

Connect Claude Code, Cursor, Windsurf, or any MCP client to inspect, modify, and export design documents headlessly. 100+ tools. Full docs →

Stdio (Claude Code, Cursor, Windsurf):

npm install -g @open-pencil/mcp
claude mcp add --scope user open-pencil -- openpencil-mcp

For other MCP clients:

{
  "mcpServers": {
    "open-pencil": {
      "command": "openpencil-mcp"
    }
  }
}

HTTP (scripts, CI):

openpencil-mcp-http   # Unix socket on macOS/Linux + http://127.0.0.1:7600/mcp

Set OPENPENCIL_MCP_ROOT to limit file access to one directory; it defaults to the current working directory.

AI agent skill

Teach your AI coding agent to use OpenPencil — inspect designs, export assets, analyze tokens, modify .fig files:

npx skills add open-pencil/open-pencil

Works with Claude Code, Cursor, Windsurf, Codex, and any agent that supports skills.

For documentation-aware agents, the docs site publishes llms.txt, llms-full.txt, and per-page Markdown files generated from the VitePress docs.

Collaboration

Share a link to co-edit in real time. No server, no account — peers connect directly via WebRTC.

  1. Click the share button in the top-right panel
  2. Share the generated link (app.openpencil.dev/share/<room-id>)
  3. Collaborators see your cursor, selection, and edits in real time
  4. Click a peer's avatar to follow their viewport

Why

Figma is a closed platform that actively fights programmatic access. Their MCP server is read-only. figma-use added full read/write automation via CDP — then Figma 126 killed CDP. Your design files are in a proprietary binary format that only their software can fully read. Your workflows break when they decide to ship a point release.

OpenPencil is the alternative: open source (MIT), reads .fig files natively, every operation is scriptable, and your data never leaves your machine.

See the roadmap for product direction and current Figma compatibility gaps.

Community

Contributing

bun install
bun run dev:portless  # Web editor at https://open-pencil.localhost
bun run tauri dev     # Desktop app (requires Rust)

CONTRIBUTING.md covers setup, quality gates, pull requests, and commits. AGENTS.md maps the repository and links the guide inside each package. Desktop builds need Rust and the Tauri v2 prerequisites; run bun run tauri build.

Tech stack

Layer Tech
Rendering Skia (CanvasKit WASM)
Layout Yoga WASM (flex + grid via fork)
UI Vue 3, Reka UI, Tailwind CSS 4
File format Kiwi binary + Zstd + ZIP
Collaboration Trystero (WebRTC P2P) + Yjs (CRDT)
Desktop Tauri v2
AI/MCP Vercel AI SDK (multi-provider BYOK), MCP SDK, Hono

Acknowledgments

Thanks to @sld0Ant (Anton Soldatov) for creating and maintaining the documentation site.

License

OpenPencil is licensed under the MIT License.

Copyright (c) 2026 Danila Poyarkov and OpenPencil contributors.