Drawgent: coding agent on a live Excalidraw canvas

drawgent is a small open-source project that connects a coding agent to a live Excalidraw whiteboard. Published on the Tangled code host, it is a single Rust binary (roughly 82% of the repository is Rust, 12.5% JavaScript) that serves an Excalidraw editor and links the user's own Claude Code, Codex or opencode installation to it. The repository appeared with a single commit.

Bring your own agent

drawgent never bundles an agent. The setup command (drawgent setup claude|codex|opencode) checks that the chosen CLI is on the PATH, verifies the login, prepares an ACP bridge and writes its configuration to ~/.config/drawgent/config.toml. opencode speaks ACP natively, while Claude Code and Codex use official adapters, installed into a cache of about 60 MB and pointed at the user's own CLI. A headless Chrome renderer (Chrome Headless Shell, about 120 MB) can be downloaded without sudo.

The canvas as an interface

drawgent up starts the editor and API on 127.0.0.1:7300, or the next free port if that one is taken, opens a new agent session in the current directory and launches the browser. The scene lives in .drawgent/scene.json, which git ignores automatically. A request can be typed into the chat panel, where replies and tool calls stream in and permission prompts are approved, or written on the canvas as a note starting with AGENT: next to a shape. Such a note fires about 2.5 seconds after typing stops and carries its position and context; the agent looks at the canvas through a screenshot and the scene, edits the drawing live and marks the note green as DONE. Prompts are queued and run one at a time.

Attaching, rooms and MCP tools

With drawgent up --attach the canvas connects to a session that is already running. Claude Code is attached by forking the conversation over ACP, so the terminal session is left untouched; opencode is driven live through its local server, and Codex through codex queue. The agent sees the drawing through MCP tools such as get_scene, get_screenshot, update_elements and add_mermaid. The --room option makes drawgent join an excalidraw.com room as a collaborator; traffic is end-to-end encrypted with the room key. By default, drawing tools are approved automatically while anything else is asked in the chat panel.

Limits

The README lists several caveats: the renderer still requires Chrome, with a native one planned, and Claude attach is a fork because Claude Code offers no public way to inject into a running terminal session. Live Codex attach is implemented but has not been tested yet against a logged-in Codex, there is one scene per workspace, and images or files are not synced.