canvas

A tool for showing HTML web content on connected Mac, iPhone, iPad, and Android devices through their canvas views. HTML is the standard format used to build web pages.

In plain words
What is it for?
Use it to display dashboards, games, visualizations, generated web pages, and interactive demos on connected devices.
Why use it?
It lets you send a web page or interactive display to another connected device instead of viewing it only on the computer where it was created.

Skill for Claude CodeCodex

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add skills/beita6969/scienceclaw/canvas
Any agent
npx skills add beita6969/ScienceClaw --skill canvas
Clone the repo
git clone --depth 1 https://github.com/beita6969/ScienceClaw

Made for: Claude Code, Codex.

Per session 0 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,421 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 1 finding. Scan, not verified.
Origin 88% copy Near-identical to another mod in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.00000 $0.01421
Opus 5 $0.00000 $0.00711
Sonnet 5 $0.00000 $0.00284
Haiku 4.5 $0.00000 $0.00142

Measured yesterday against content hash 931e65501872, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

canvas scanned grade A with 1 finding against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured yesterday.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Makes network callslowCapability

Not a fault in itself. Listed so you know the mod talks to something, and to what.

3. Test URL directly: `curl http://<hostname>:18793/__openclaw__/canvas/<file>.html`
Origin

This is a copy

88% identical to canvas — 7 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.

skills/canvas/SKILL.md · 199 lines

How it starts

The opening of the file, as written. The whole thing — 199 lines — stays where its author put it; the contents beside it link to each section on GitHub.

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

Read the full file on GitHub · 199 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. yesterday First seen · 199 lines · 0 tokens per session scan A 931e65501872

Subscribe to this mod's changes

canvas is a skill published in the GitHub repository beita6969/ScienceClaw (886 stars, last pushed 2mo ago), licensed MIT. It costs nothing until one of its globs matches a file; then it loads 1,421 tokens. A static security scan graded it A with 1 finding (makes network calls). It is 88% identical to canvas, differing in 7 lines, and is treated as a copy.

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