Skip to main content
The macOS app embeds an agent-controlled Canvas panel using WKWebView, a lightweight visual workspace for HTML/CSS/JS, A2UI, and small interactive UI surfaces.

​
Where Canvas lives

Canvas state is stored under Application Support:
  • ~/Library/Application Support/OpenClaw/canvas/<session>/...
The Canvas panel serves those files via a custom URL scheme, openclaw-canvas://<session>/<path>:
  • openclaw-canvas://main/ -> <canvasRoot>/main/index.html
  • openclaw-canvas://main/assets/app.css -> <canvasRoot>/main/assets/app.css
  • openclaw-canvas://main/widgets/todo/ -> <canvasRoot>/main/widgets/todo/index.html
If no index.html exists at the root, the app shows a built-in scaffold page.

​
Panel behavior

  • Borderless, resizable panel anchored near the menu bar (or mouse cursor).
  • Remembers size/position per session.
  • Auto-reloads when local canvas files change.
  • Only one Canvas panel is visible at a time (session switches as needed).
Canvas can be disabled from Settings -> Allow Canvas. When disabled, canvas node commands return CANVAS_DISABLED.

​
Agent API surface

Canvas is exposed via the Gateway WebSocket, so the agent can show/hide the panel, navigate to a path or URL, evaluate JavaScript, and capture a snapshot image:
canvas.navigate accepts local canvas paths, http(s) URLs, and file:// URLs. Passing "/" shows the local scaffold or index.html. Gateway-hosted targets under /__openclaw__/canvas/ and /__openclaw__/a2ui/ are resolved through the node session’s current scoped Canvas URL. The app refreshes that short-lived capability before navigation; you do not need to construct or copy a capability URL yourself.

​
A2UI in Canvas

A2UI is hosted by the Gateway canvas host and rendered inside the Canvas panel. When the Gateway advertises a Canvas host, the macOS app auto-navigates to the A2UI host page on first open. The advertised URL is capability-scoped, for example http://<gateway-host>:18789/__openclaw__/cap/<token>/__openclaw__/a2ui/?platform=macos. Treat it as ephemeral credentials, not a stable link.

​
A2UI commands (v0.8)

Canvas accepts A2UI v0.8 server-to-client messages: beginRendering, surfaceUpdate, dataModelUpdate, deleteSurface. createSurface (v0.9) is not supported yet.
Quick smoke test:

​
Triggering agent runs from Canvas

Canvas can trigger new agent runs via openclaw://agent?... deep links:
Supported query parameters: The app prompts for confirmation unless a valid key is provided. Unkeyed links show the message and URL before approval, and ignore delivery routing fields; keyed links use the normal Gateway run path.

​
Security notes

  • Canvas scheme blocks directory traversal; files must live under the session root.
  • Local Canvas content uses a custom scheme (no loopback server required).
  • External http(s) URLs are allowed only when explicitly navigated.
  • Ordinary web pages are render-only. Agent actions are accepted only from the app-owned Canvas scheme or the exact capability-scoped Gateway A2UI document selected by the app; subframes, redirects, stale capabilities, and changed queries cannot dispatch actions.