Agent Canvas

An AI agent skill for drawing diagrams, flowcharts, and visualizations on Excalidraw.

Features

🔌 Works with any AI agent — Claude Code, Codex, Cursor, or any agent that supports skills and bash.

🧠 Context-aware — Unlike web-based drawing tools, your agent sees your entire codebase. Ask it to "draw the architecture of this project" and it will analyze your code structure to generate accurate diagrams.

⚡ Token efficient — CLI commands instead of generating .excalidraw JSON (thousands of tokens per element):

# JSON approach: 500+ tokens per shape
# CLI approach: ~50 tokens
agent-canvas add-shape -t rectangle -x 100 -y 100 -l "Hello"

🔄 Real-time & iterative — See changes instantly in browser. Use --animated to auto-zoom to each new element and watch the diagram being built step by step. Refine through natural conversation: "make the boxes blue", "add a database layer".

👀 Bidirectional — Agent can export and view the canvas anytime. Make manual edits in Excalidraw, then ask the agent to continue — no screenshots needed.

📦 Easy setup — Skill automatically installs and updates the CLI. Just start drawing.

🗂️ Multi-canvas — Work on multiple diagrams simultaneously. Switch between canvases via sidebar or CLI commands.

🧩 Extensible — Add custom drawing tutorials in references/ to teach your agent domain-specific diagram styles.

Installation

npx skills add WHQ25/agent-canvas --skill agent-canvas

This installs the skill to your AI coding agent (Claude Code, Codex, Cursor, etc.).

After installation, just ask your agent to draw something:

• "Draw a flowchart for user authentication"
• "Create an architecture diagram for a microservices system"
• "Sketch a mind map for project planning"

How It Works

1. agent-canvas start opens a local Excalidraw canvas in your browser
2. CLI sends drawing commands via WebSocket, canvas updates in real-time
3. You and your agent collaborate on the same canvas

flowchart LR
    A[You] -->|natural language| B[AI Agent]
    A -->|edit directly| D
    B -->|CLI commands| C[CLI Server]
    B -.->|reads| E[Codebase +\nSkill tutorials]
    C <-->|WebSocket| D[Browser\nExcalidraw]

Examples

Sequence Diagram

Prompt:

Draw a sequence diagram for WeChat OAuth login flow

Output:

Flowchart with Iterative Refinement

Prompt 1:

Draw a flowchart for the add-text command processing flow

Prompt 2 (refining):

Show all 9 anchor types in a grid, use dashed rectangle to group them

Output:

Architecture Diagram

Prompt:

Draw an architecture diagram for the Excalidraw project based on its codebase structure

Output:

UI Mockup

Prompt:

Design an e-commerce app with product detail, shopping cart, and checkout pages

Output:

CLI Installation

The skill will guide the agent to install the CLI automatically. You can also install it manually:

npm install -g @agent-canvas/cli

Contributing

Contributions are welcome!

The skill is located in skills/agent-canvas/:

• SKILL.md - CLI command reference (how to use each command)
• references/ - Drawing tutorials for specific diagram types (flowcharts, UI mockups, etc.)

How to contribute:

1. Add new drawing tutorials to skills/agent-canvas/references/
2. Improve the CLI tool in packages/cli/
3. Report issues or suggest features

Development

# Install dependencies
bun install

# Start dev server (Vite HMR + WS relay, no build needed)
bun run dev

# Run CLI commands during development
bun dev:cli <command>
# Example: bun dev:cli add-shape -t rectangle -x 100 -y 100

# Build all packages
bun run build

bun run dev starts a Vite dev server with hot module replacement — web-app changes auto-reload in the browser without rebuilding.