Canvas OS

Canvas as an app platform. Build, store, and run rich visual apps on the OpenClaw Canvas.

Philosophy

You are an OS. Canvas is the window. Apps are built locally and run on Canvas.

Rich HTML/CSS/JS UIs — not just text. Full interactivity, animations, live data.

Quick Commands

How It Works

Key principle: Apps run on Canvas, not in a browser tab. Canvas is your UI window.

Canvas Loading Methods

Canvas has security restrictions that block file path access. Three methods work:

❌ Does NOT work: file:///path/to/file.html (blocked by Canvas security)

📖 See: CANVAS-LOADING.md for detailed guide + troubleshooting

Helper script: canvas-inject.py — Formats HTML for direct injection

1. Apps are HTML/CSS/JS files

~/.openclaw/workspace/apps/[app-name]/
├── index.html    # The UI (self-contained recommended)
├── data.json     # Persistent state
└── manifest.json # App metadata

2. Serve via localhost

cd ~/.openclaw/workspace/apps/[app-name]
python3 -m http.server [PORT] > /dev/null 2>&1 &

3. Navigate Canvas to localhost

NODE="Your Node Name"  # Get from: openclaw nodes status
openclaw nodes canvas navigate --node "$NODE" "http://localhost:[PORT]/"

Important: This opens the app on Canvas (the visual panel), NOT in a browser.

4. Agent injects data via JS eval

openclaw nodes canvas eval --node "$NODE" --js "app.setData({...})"

Note: The openclaw-canvas:// URL scheme has issues in current OpenClaw versions. Use http://localhost: instead.

Opening an App

What this does: Displays the app on Canvas (the visual panel), not in a browser tab.

Method 1: Localhost Server (Recommended for Complex Apps)

Full sequence:

NODE="Your Node Name"
PORT=9876
APP="my-app"

# 1. Kill any existing server on the port
lsof -ti:$PORT | xargs kill -9 2>/dev/null

# 2. Start server
cd ~/.openclaw/workspace/apps/$APP
python3 -m http.server $PORT > /dev/null 2>&1 &

# 3. Wait for server
sleep 1

# 4. Navigate Canvas
openclaw nodes canvas navigate --node "$NODE" "http://localhost:$PORT/"

# 5. Inject data
openclaw nodes canvas eval --node "$NODE" --js "app.loadData({...})"

Method 2: Direct HTML Injection (For Quick Displays)

When to use: File paths don't work in Canvas (security sandboxing). Data URLs can be unreliable. Use this for instant displays without localhost.

# Example using canvas tool
canvas.present(url="about:blank", target=node_name)

html_content = """\x3C!DOCTYPE html>
\x3Chtml>
\x3Chead>
    \x3Cstyle>
        body { background: #667eea; color: white; padding: 40px; }
        .card { background: white; color: #333; padding: 30px; border-radius: 16px; }
    \x3C/style>
\x3C/head>
\x3Cbody>
    \x3Cdiv class="card">
        \x3Ch1>Your Content Here\x3C/h1>
    \x3C/div>
\x3C/body>
\x3C/html>"""

# Escape backticks and inject
js_code = f"""document.open();
document.write(`{html_content}`);
document.close();"""

canvas.eval(javaScript=js_code, target=node_name)

Key limitation: File paths (file:///path/to/file.html) are blocked in Canvas for security. Always use localhost or direct injection.

Building Apps

App API Convention

Every app should expose a window.app or window.[appname] object:

window.app = {
  // Update values
  setValue: (key, val) => {
    document.getElementById(key).textContent = val;
  },
  
  // Bulk update
  loadData: (data) => { /* render all */ },
  
  // Notifications
  notify: (msg) => { /* show toast */ }
};

Two-Way Communication

Apps send commands back via deep links:

function sendToAgent(message) {
  window.location.href = `openclaw://agent?message=${encodeURIComponent(message)}`;
}

// Button click → agent command
document.getElementById('btn').onclick = () => {
  sendToAgent('Refresh my dashboard');
};

Templates

Dashboard

Stats cards, progress bars, lists. Self-contained HTML.

• Default port: 9876
• API: dashboard.setRevenue(), dashboard.setProgress(), dashboard.notify()

Tracker

Habits/tasks with checkboxes and streaks. Self-contained HTML.

• Default port: 9877
• API: tracker.setItems(), tracker.addItem(), tracker.toggleItem()

Quick Display (A2UI)

For temporary displays without a full app:

openclaw nodes canvas a2ui push --node "$NODE" --text "
📊 QUICK STATUS

Revenue: \$500
Users: 100

Done!
"

Port Assignments

Design System

:root {
  --bg-primary: #0a0a0a;
  --bg-card: #1a1a2e;
  --accent-green: #00d4aa;
  --accent-blue: #4a9eff;
  --accent-orange: #f59e0b;
  --text-primary: #fff;
  --text-muted: #888;
  --border: #333;
}

Best Practices

1. Self-contained HTML — Inline CSS/JS for portability
2. Dark theme — Match OpenClaw aesthetic
3. Expose app API — Let agent update via window.app.*
4. Use IDs — On elements the agent will update
5. Live clock — Shows the app is alive
6. Deep links — For two-way communication

Troubleshooting

App opens in browser instead of Canvas?

• Make sure you're using openclaw nodes canvas navigate, not just open
• Canvas navigate targets the Canvas panel specifically

"Not Found" on Canvas?

• File paths don't work: Canvas blocks file:/// URLs for security (sandboxing)
• Data URLs may fail: Use direct HTML injection via canvas eval + document.write() instead
• For localhost: Verify server is running: curl http://localhost:[PORT]/
• Check port is correct
• Use http://localhost: not openclaw-canvas:// (URL scheme has issues)

Canvas shows "Not Found" even with correct URL?

• This is a security boundary: Canvas can't access local filesystem
• Solution: Use Method 2 (Direct HTML Injection) from "Opening an App" section
• Or serve via localhost (Method 1)

App not updating?

• Check window.app API is defined: openclaw nodes canvas eval --js "typeof window.app"
• Verify JS eval syntax: single quotes inside double quotes

Server port already in use?

• Kill existing: lsof -ti:[PORT] | xargs kill -9

Helper Scripts

canvas-inject.py

Python helper for direct HTML injection (Method 2).

# Example usage in Python
from canvas_inject import inject_html_to_canvas

html = open("my-dashboard.html").read()
commands = inject_html_to_canvas(html, node_name="Your Node")

# Then use canvas tool with these commands
canvas.present(**commands["step1_present"])
canvas.eval(**commands["step2_inject"])

Or just follow the pattern manually (see Method 2 in "Opening an App").

Requirements

• OpenClaw with Canvas support (macOS app)
• Python 3 (for http.server)
• A paired node with canvas capability