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Canvas (macOS app)

The macOS app embeds an agent‑controlled Canvas panel using WKWebView. It is a lightweight visual workspace for HTML/CSS/JS, A2UI, and small interactive UI surfaces.

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Where Canvas lives

Canvas state is stored under Application Support:
  • ~/Library/Application Support/Clawdbot/canvas/<session>/...
The Canvas panel serves those files via a custom URL scheme:
  • clawdbot-canvas://<session>/<path>
Examples:
  • clawdbot-canvas://main/ → <canvasRoot>/main/index.html
  • clawdbot-canvas://main/assets/app.css → <canvasRoot>/main/assets/app.css
  • clawdbot-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.

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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 is switched as needed).
Canvas can be disabled from Settings → Allow Canvas. When disabled, canvas node commands return CANVAS_DISABLED.

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Agent API surface

Canvas is exposed via the node bridge, so the agent can:
  • show/hide the panel
  • navigate to a path or URL
  • evaluate JavaScript
  • capture a snapshot image
CLI examples: 
clawdbot nodes canvas present --node <id>
clawdbot nodes canvas navigate --node <id> --url "/"
clawdbot nodes canvas eval --node <id> --js "document.title"
clawdbot nodes canvas snapshot --node <id>
Notes:
  • canvas.navigate accepts local canvas paths, http(s) URLs, and file:// URLs.
  • If you pass "/", the Canvas shows the local scaffold or index.html.

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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. Default A2UI host URL: 
http://<gateway-host>:18793/__clawdbot__/a2ui/

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A2UI commands (v0.8)

Canvas currently accepts A2UI v0.8 server→client messages:
  • beginRendering
  • surfaceUpdate
  • dataModelUpdate
  • deleteSurface
createSurface (v0.9) is not supported. CLI example: 
cat > /tmp/a2ui-v0.8.jsonl <<'EOFA2'
{"surfaceUpdate":{"surfaceId":"main","components":[{"id":"root","component":{"Column":{"children":{"explicitList":["title","content"]}}}},{"id":"title","component":{"Text":{"text":{"literalString":"Canvas (A2UI v0.8)"},"usageHint":"h1"}}},{"id":"content","component":{"Text":{"text":{"literalString":"If you can read this, A2UI push works."},"usageHint":"body"}}}]}}
{"beginRendering":{"surfaceId":"main","root":"root"}}
EOFA2

clawdbot nodes canvas a2ui push --jsonl /tmp/a2ui-v0.8.jsonl --node <id>
Quick smoke: 
clawdbot nodes canvas a2ui push --node <id> --text "Hello from A2UI"

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Triggering agent runs from Canvas

Canvas can trigger new agent runs via deep links:
  • clawdbot://agent?...
Example (in JS): 
window.location.href = "clawdbot://agent?message=Review%20this%20design";
The app prompts for confirmation unless a valid key is provided.

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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.