canvas

A skill for displaying HTML content on connected Mayros devices such as Macs, iPhones, and Android phones. It can show web pages, games, dashboards, and interactive demonstrations on a device canvas.

In plain words
What is it for?
Use it to serve HTML, CSS, and JavaScript content and open it on connected devices for demos, visualisations, dashboards, or interactive interfaces.
Why use it?
It provides a way to present locally served HTML content on another connected screen instead of limiting the display to the development machine.

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/apiliumcode/mayros/canvas
Any agent
npx skills add ApiliumCode/mayros --skill canvas
Clone the repo
git clone --depth 1 https://github.com/ApiliumCode/mayros

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 1,407 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 1 finding. Scan, not verified.
Origin original No closer match found 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 $0.01407
Opus 5 $0.00000 $0.00704
Sonnet 5 $0.00000 $0.00281
Haiku 4.5 $0.00000 $0.00141

Measured 2d ago against content hash 2baae4a31ade, 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 2d ago.

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/__mayros__/canvas/<file>.html`
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 Mayros 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/__mayros__/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. 2d ago First seen · 199 lines · 0 tokens per session scan A 2baae4a31ade

Subscribe to this mod's changes

canvas is a skill published in the GitHub repository ApiliumCode/mayros (12 stars, last pushed 1mo ago), licensed MIT. It costs nothing until one of its globs matches a file; then it loads 1,407 tokens. A static security scan graded it A with 1 finding (makes network calls). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.