Agent skill

canvas

View SKILL.md on GitHub Repository
Stars 1,878
Forks 294

Install this agent skill to your Project

npx add-skill https://github.com/LeoYeAI/openclaw-master-skills/tree/main/skills/canvas

SKILL.md

Canvas Skill

Display HTML content on connected OpenClaw nodes (Mac app, iOS, Android).

Overview

The canvas tool lets you present web content on any connected node's canvas view. Great for:

  • Displaying games, visualizations, dashboards
  • Showing generated HTML content
  • Interactive demos

How It Works

Architecture

┌─────────────────┐     ┌──────────────────┐     ┌─────────────┐
│  Canvas Host    │────▶│   Node Bridge    │────▶│  Node App   │
│  (HTTP Server)  │     │  (TCP Server)    │     │ (Mac/iOS/   │
│  Port 18793     │     │  Port 18790      │     │  Android)   │
└─────────────────┘     └──────────────────┘     └─────────────┘
  1. Canvas Host Server: Serves static HTML/CSS/JS files from canvasHost.root directory
  2. Node Bridge: Communicates canvas URLs to connected nodes
  3. Node Apps: Render the content in a WebView

Tailscale Integration

The canvas host server binds based on gateway.bind setting:

Bind Mode Server Binds To Canvas URL Uses
loopback 127.0.0.1 localhost (local only)
lan LAN interface LAN IP address
tailnet Tailscale interface Tailscale hostname
auto Best available Tailscale > LAN > loopback

Key insight: The canvasHostHostForBridge is derived from bridgeHost. When bound to Tailscale, nodes receive URLs like:

http://<tailscale-hostname>:18793/__openclaw__/canvas/<file>.html

This is why localhost URLs don't work - the node receives the Tailscale hostname from the bridge!

Actions

Action Description
present Show canvas with optional target URL
hide Hide the canvas
navigate Navigate to a new URL
eval Execute JavaScript in the canvas
snapshot Capture screenshot of canvas

Configuration

In ~/.openclaw/openclaw.json:

json
{
  "canvasHost": {
    "enabled": true,
    "port": 18793,
    "root": "/Users/you/clawd/canvas",
    "liveReload": true
  },
  "gateway": {
    "bind": "auto"
  }
}

Live Reload

When liveReload: true (default), the canvas host:

  • Watches the root directory for changes (via chokidar)
  • Injects a WebSocket client into HTML files
  • Automatically reloads connected canvases when files change

Great for development!

Workflow

1. Create HTML content

Place files in the canvas root directory (default ~/clawd/canvas/):

bash
cat > ~/clawd/canvas/my-game.html << 'HTML'
<!DOCTYPE html>
<html>
<head><title>My Game</title></head>
<body>
  <h1>Hello Canvas!</h1>
</body>
</html>
HTML

2. Find your canvas host URL

Check how your gateway is bound:

bash
cat ~/.openclaw/openclaw.json | jq '.gateway.bind'

Then construct the URL:

  • loopback: http://127.0.0.1:18793/__openclaw__/canvas/<file>.html
  • lan/tailnet/auto: http://<hostname>:18793/__openclaw__/canvas/<file>.html

Find your Tailscale hostname:

bash
tailscale status --json | jq -r '.Self.DNSName' | sed 's/\.$//'

3. Find connected nodes

bash
openclaw nodes list

Look for Mac/iOS/Android nodes with canvas capability.

4. Present content

canvas action:present node:<node-id> target:<full-url>

Example:

canvas action:present node:mac-63599bc4-b54d-4392-9048-b97abd58343a target:http://peters-mac-studio-1.sheep-coho.ts.net:18793/__openclaw__/canvas/snake.html

5. Navigate, snapshot, or hide

canvas action:navigate node:<node-id> url:<new-url>
canvas action:snapshot node:<node-id>
canvas action:hide node:<node-id>

Debugging

White screen / content not loading

Cause: URL mismatch between server bind and node expectation.

Debug steps:

  1. Check server bind: cat ~/.openclaw/openclaw.json | jq '.gateway.bind'
  2. Check what port canvas is on: lsof -i :18793
  3. Test URL directly: curl http://<hostname>:18793/__openclaw__/canvas/<file>.html

Solution: Use the full hostname matching your bind mode, not localhost.

"node required" error

Always specify node:<node-id> parameter.

"node not connected" error

Node is offline. Use openclaw nodes list to find online nodes.

Content not updating

If live reload isn't working:

  1. Check liveReload: true in config
  2. Ensure file is in the canvas root directory
  3. Check for watcher errors in logs

URL Path Structure

The canvas host serves from /__openclaw__/canvas/ prefix:

http://<host>:18793/__openclaw__/canvas/index.html  → ~/clawd/canvas/index.html
http://<host>:18793/__openclaw__/canvas/games/snake.html → ~/clawd/canvas/games/snake.html

The /__openclaw__/canvas/ prefix is defined by CANVAS_HOST_PATH constant.

Tips

  • Keep HTML self-contained (inline CSS/JS) for best results
  • Use the default index.html as a test page (has bridge diagnostics)
  • The canvas persists until you hide it or navigate away
  • Live reload makes development fast - just save and it updates!
  • A2UI JSON push is WIP - use HTML files for now

Recommended Agent Skills

Expand your agent's capabilities with these related and highly-rated skills.

LeoYeAI/openclaw-master-skills

audit-website

Audit websites for SEO, performance, security, technical, content, and 15 other issue cateories with 230+ rules using the squirrelscan CLI. Returns LLM-optimized reports with health scores, broken links, meta tag analysis, and actionable recommendations. Use to discover and asses website or webapp issues and health.

1,878 294
Explore
LeoYeAI/openclaw-master-skills

firecrawl

Web search and scraping via Firecrawl API. Use when you need to search the web, scrape websites (including JS-heavy pages), crawl entire sites, or extract structured data from web pages. Requires FIRECRAWL_API_KEY environment variable.

1,878 294
Explore
LeoYeAI/openclaw-master-skills

computer-use

Full desktop computer use for headless Linux servers. Xvfb + XFCE virtual desktop with xdotool automation. 17 actions (click, type, scroll, screenshot, drag, etc). Unlike OpenClaw's browser tool, operates at the X11 level so websites cannot detect automation. Includes VNC for live viewing.

1,878 294
Explore
LeoYeAI/openclaw-master-skills

social-media-analyzer

Social media campaign analysis and performance tracking. Calculates engagement rates, ROI, and benchmarks across platforms. Use for analyzing social media performance, calculating engagement rate, measuring campaign ROI, comparing platform metrics, or benchmarking against industry standards.

1,878 294
Explore
LeoYeAI/openclaw-master-skills

business-growth-skills

4 production-ready business and growth skills: customer success manager with health scoring and churn prediction, sales engineer with RFP analysis, revenue operations with pipeline and GTM metrics, and contract & proposal writer. Python tools included (all stdlib-only). Works with Claude Code, Codex CLI, and OpenClaw.

1,878 294
Explore
LeoYeAI/openclaw-master-skills

contract-and-proposal-writer

Contract & Proposal Writer

1,878 294
Explore

Didn't find tool you were looking for?

Be as detailed as possible for better results