Tldraw Offline

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):

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.