tldraw offline Skill

Work with the tldraw offline desktop app (offline.tldraw.com): read the open
canvas, make edits, and write document scripts — JavaScript embedded in a
.tldraw file that runs on load and gives the file durable behavior. The app
runs a local HTTP API (default localhost:7236) that a coding agent drives
with plain curl from its terminal — this is exactly how the app's own homepage
demo (Codex editing a canvas live) works. The agent does NOT use computer-use /
GUI clicking, and does NOT hand-edit the .tldraw file directly. Keep tldraw
offline open while you work.

When to Use

• The user has tldraw offline open and asks you to build or modify a canvas
  (diagrams, wireframes, layouts).
• You want to add durable behavior to a drawing (reactive shapes, interactive
  buttons, animation, connection logic) via an embedded document script.

Do NOT hand-place shapes to imitate a drawing — write the code that generates
them. Agents are far better at scripting the canvas than at drawing on it.

Prerequisites

• tldraw offline installed and running, with a document open. Releases:
  https://github.com/tldraw/tldraw-offline/releases/latest (macOS DMG, Windows
  x64/Arm64, Linux x86_64/arm64 AppImage or amd64/arm64 .deb).
• Agent skills installed in the app: Develop → Install Agent Skills. The
  app writes its own tldraw skill into ~/.codex/skills/, ~/.claude/skills/,
  ~/.cursor/skills/, and ~/.gemini/skills/ — teaching that agent the curl
  recipes below. (This Loki skill mirrors that guidance for Loki.)
• The local control API. On launch the app writes server.json to its config
  dir (Linux ~/.config/tldraw/, macOS ~/Library/Application Support/tldraw/,
  Windows %APPDATA%\tldraw\) with port (default 7236), a bearer token,
  pid, and startedAt. Every request except GET / needs
  Authorization: Bearer <token>. A clean quit removes server.json; if it's
  present but the port doesn't answer, the app quit uncleanly — treat as not
  running.
• Re-read port + token on EVERY shell call. Each terminal call is a fresh
  shell, so an exported token does not persist — "export once and reuse" sends
  an empty token and 401s. Read both inline at the top of each call:
  PORT=$(jq -r .port <server.json>); TOKEN=$(jq -r .token <server.json>).
• No account or network needed for local editing.

How to Run

Two distinct workflows. Pick by whether the change must survive a reload.

A. One-off canvas edits (/exec) — layout, generating shapes, cleanup. This
is a live edit, not saved script:

BASE=http://localhost:7236
TOKEN=$(python -c "import json;print(json.load(open('$HOME/.config/tldraw/server.json'))['token'])")
# find the focused document id
DOC=$(curl -s "$BASE/api/search" -X POST -H 'content-type: application/json' \
  -H "Authorization: Bearer $TOKEN" \
  -d '{"code":"return (await api.getFocusedDoc()).id"}' | python -c "import sys,json;print(json.load(sys.stdin)['result'])")
# run code with the live `editor` + `helpers` in scope
curl -s "$BASE/api/doc/$DOC/exec" -X POST -H 'content-type: application/json' \
  -H "Authorization: Bearer $TOKEN" \
  -d '{"code":"const {createShapeId,toRichText}=await import(\"tldraw\"); editor.createShape({id:createShapeId(),type:\"geo\",x:0,y:0,props:{geo:\"rectangle\",w:200,h:100,color:\"blue\",fill:\"solid\",richText:toRichText(\"hello\")}}); return editor.getCurrentPageShapes().length"}'

B. Durable behavior (script/main.js) — reactive/interactive logic that must
survive reload. Edit the file on disk; the app's watcher applies it:

# get the live script file path for the doc
curl -s "$BASE/api/doc/$DOC/script-workspace" -X POST \
  -H "Authorization: Bearer $TOKEN"          # -> result.mainJsPath, result.isDefaultScript
# edit result.mainJsPath with read_file / patch / write_file (see scripts/main.js)
# then confirm the watcher applied it:
curl -s "$BASE/api/doc/$DOC/script-status" -H "Authorization: Bearer $TOKEN"

The ready-to-adapt document script is scripts/main.js.

Quick Reference

The document-script contract (verified against the app's bundled
script-context.d.ts):

import { createShapeId, toRichText } from 'tldraw'   // primitives: import, not globals

export default function ({ editor, helpers, signal }) {
  editor.run(() => {                                 // batch = one undo step
    helpers.createShapeIfMissing({                   // idempotent furniture
      id: createShapeId('node-1'), type: 'geo', x: 0, y: 0,
      props: { geo: 'rectangle', w: 200, h: 100, richText: toRichText('hi') },
    })
  })

  const stop = editor.store.listen(() => { /* react */ })  // fires the tick AFTER a commit
  signal.addEventListener('abort', () => stop())           // REQUIRED cleanup on rerun/close
}

• ctx.editor — the live Editor (createShape, updateShape, deleteShapes,
  getCurrentPageShapes, getShape, getBindingsFromShape, zoomToFit,
  on('tick'|'event', fn), run(fn, { history: 'ignore' })).
• ctx.helpers — createShapeIfMissing, createShapesIfMissing,
  createArrowBetweenShapes(from, to, { arrowheadEnd }), translateShapes,
  onShapeTranslate(id, fn, { signal }), richTextToPlainText, boxShapes,
  getLints.
• ctx.signal — AbortSignal; attach every listener/interval teardown to it.
• config.js (separate file) registers custom shape/tool/component utils and
  runs before mount; main.js runs against the mounted editor and reruns on save.

Interactive UI (clickable buttons that drive state)

Drawn shapes can behave like a real app — the thing a static whiteboard can't do.
Full example: scripts/counter.js (a number display + MINUS/RESET/PLUS buttons).

Verification boundary — read this before claiming interaction works or doesn't.
The app's OWN agent playbook says to verify a clickable-UI script with "one
simulated click and one state read" via /exec (editor.dispatch a pointer
event, await a tick, read the shape's state) — NOT by driving a real mouse. By
that standard the counter is verified: dispatched clicks stepped it
0 → 1 → 2 → 1 → 0. Two caveats worth writing down:

• The script only runs once the app's file-watcher applies it. On Linux that
  watcher uses inotify; a host with an exhausted fs.inotify.max_user_instances
  logs inotify_add_watch ... No space left on device, script-status shows
  state: "not-watching" / hasEntry: false, and the script never executes.
  This is a host limit, not a script bug — a normal desktop is unaffected.
• Driving the canvas with computer-use needs FOREGROUND delivery, not
  background. cua-driver's default background delivery returns
  background_unavailable against Electron's occluded renderer — but that is the
  first rung, not a wall. cua-driver returns an escalation: "foreground" hint;
  set delivery_mode: "foreground" (pair with bring_to_front) and its X11 XTest
  path (x11_xtest_fg) clicks land — this dismisses the "Run Script" consent
  dialog and clicks the canvas. Verified by the Cua team on this exact v1.11.0
  AppImage (Linux/X11). Do NOT conclude "Electron rejects synthetic clicks" and
  give up in background mode — climb to foreground. (The real product path is
  still /exec, not clicks; this note is for computer-use-driven testing.)

The pattern:

export default function ({ editor, helpers, signal }) {
  // 1. Build buttons idempotently; tag each with meta so the handler finds them.
  //    Give buttons a visible label AND a meta.action.
  // 2. Hit-test pointer_down in PAGE coordinates against the button bounds:
  const inside = (b, p) => p.x >= b.x && p.x <= b.x + b.w && p.y >= b.y && p.y <= b.y + b.h
  function onEvent(info) {
    if (!info || info.name !== 'pointer_down') return
    let p = null
    try { if (info.point && editor.screenToPage) p = editor.screenToPage(info.point) } catch {}
    p = p ?? editor.inputs?.currentPagePoint
    if (!p) return
    const hit = editor.getCurrentPageShapes().find(
      (s) => s.meta?.ui === 'button' &&
        inside({ x: s.x, y: s.y, w: s.props.w, h: s.props.h }, p)
    )
    if (hit) runAction(hit.meta.action)   // mutate state; store it in a shape's meta
  }
  editor.on('event', onEvent)
  signal.addEventListener('abort', () => editor.off('event', onEvent))  // REQUIRED
}

• Find buttons by meta (or visible label via helpers.richTextToPlainText),
  not by hard-coded coordinates.
• One script owns both build and read. If the shapes are created by one code
  path (with meta.action: 'inc') and the handler reads another convention
  (meta.action === 'PLUS'), clicks silently do nothing. Ship the buttons built
  by the same script that handles them, or ship an empty canvas so the script
  builds them fresh — never pre-bake mismatched shapes into the file's db.
• Keep app state in a shape's meta (e.g. meta.count) and render it as that
  shape's richText label, so it survives save and is readable for verification.
• Detach the listener on signal abort. Skipping this is not cosmetic: on
  the next save the old onEvent stays attached alongside the new one, so every
  click fires twice and a counter jumps by 2 instead of 1.
• For continuous motion use editor.on('tick', fn); for a moving anchor with
  attached pieces use helpers.onShapeTranslate(id, fn, { signal }).

Shipping a self-running scripted .tldraw

A .tldraw is a zip of metadata.json + session.json + db.sqlite + assets/

• script/ (only those entries are packable). For the script to auto-run without
  the "This document contains a script → Run Script" consent dialog:

• metadata.json must carry a script manifest: { "sha256": "<digest>" }, where
  the digest is sha256 over each sorted script/ path as `${path}\0${sha256hex(bytes)}\n`.
  A mismatch is rejected as tampered.
• Pre-trust the digest by adding it to ~/.tldraw/script-trust.json
  ({ "trusted": ["<digest>"] }, or $TLDRAW_SCRIPT_TRUST). The app skips consent
  when isScriptTrusted(digest) is true.

Procedure

1. Read the current token/port from server.json. Find the target doc with
   api.getFocusedDoc() (or api.getDocs()); name it explicitly if several are
   open.
2. For layout/generation, use /exec. For durable behavior, edit
   script/main.js via /script-workspace.
3. Make scripts idempotent: create durable shapes with helpers.createShapeIfMissing
   and stable createShapeId('name') ids. Scripts rerun on every load.
4. Keep script-owned writes out of the user's undo stack:
   editor.run(fn, { history: 'ignore' }) (or helpers.translateShapes, which
   already does).
5. For reactivity, editor.store.listen(cb) and tear it down on signal abort.
   For interaction, editor.on('event', h) (hit-test pointer_down in page
   coords); for animation, editor.on('tick', h).
6. For a single moving anchor + attached internals, prefer
   helpers.onShapeTranslate(anchorId, fn, { signal }) over a broad store
   listener — a broad listener can turn your own writes into feedback loops.

Shape props (validated against tldraw SDK v5 schema)

editor.createShape / createShapeIfMissing accept partial props (shape utils
fill defaults). When building raw records for a file snapshot, every prop
below is required (run scripts/validate_shapes.mjs):

Shape	Required props
note	richText, color, labelColor, size, font, align, verticalAlign, growY, fontSizeAdjustment, url, scale, textLastEditedBy
text	richText, color, size, font, textAlign, w, scale, autoSize
frame	w, h, name, color
geo	geo, w, h, color, fill, richText (+ dash/size/etc. defaulted)

richText must be toRichText('...') — a bare string is rejected. color enum:
black grey light-violet violet blue light-blue yellow orange green light-green light-red red white. font enum: draw sans serif mono.

Pitfalls

• store.listen fires on the tick AFTER a commit, not synchrowundercorply. If you
  write a shape and immediately read state expecting the listener to have run, it
  hasn't. Verified live: an in-turn read shows 0 fires; after one setTimeout
  tick it shows 1. Same reason the app notes editor.dispatch is async — await a
  tick before verifying.
• ctx, not globals. The entry is export default function ({ editor, helpers, signal }). There is no bare editor global in a document script.
  createShapeId / toRichText / Vec come from import ... from 'tldraw'.
• richText, not text. Text/note/geo labels use richText: toRichText(s).
• Raw records need every prop; createShape does not. In-app pass only the
  props you care about; a hand-built .tldraw snapshot needs the full set (table).
• Scripts rerun on every load — be idempotent. Use createShapeIfMissing
  with stable ids or you duplicate content and clobber user edits.
• Clean up on signal. signal.addEventListener('abort', () => stop()) for
  every store.listen / editor.on / setInterval; the signal fires before
  rerun and on close.
• Keep script writes out of undo: editor.run(fn, { history: 'ignore' }).
• editor.on('tick') pauses when the window is hidden (it is a RAF loop);
  setInterval keeps firing but Electron throttles it to ~1/s in the background.
• The API needs the bearer token from server.json; the port can be non-default
  (server.listen(0) picks one) — always read the file, don't hardcode 7236.
• Only tldraw / react / react-dom import — not a Node project.

Verification

• Shape schema (offline, no app): node scripts/validate_shapes.mjs — builds
  the real tldraw schema and validates note/text/frame. Passing prints 3/3.
• Live canvas edits: after /exec, read back with /api/search →
  api.getShapes(docId) (returns { page, viewport, shapes }) and
  api.getBindings(docId) (array). Confirm expected shapes/bindings exist. Grab
  api.getScreenshot(docId) (returns { filePath, ... }) and inspect the PNG/JPEG
  with vision_analyze.
• Durable script applied: GET /api/doc/:id/script-status. Success is
  state: "applied" (currentDiskDigest === lastAppliedDigest === manifestSha256,
  pendingApply === false, lastApplyError === null). If it stays "pending"
  after a short retry, report that instead of claiming success; "error" means
  the apply failed — read errorLogPath.