Canvas

The macOS app embeds an agent‑controlled Canvas panel using

. It is a lightweight visual workspace for HTML/CSS/JS, A2UI, and small interactive UI surfaces.

Where Canvas lives

Canvas state is stored under Application Support:

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  ~/Library/Application Support/OpenClaw/canvas/<session>/...

The Canvas panel serves those files via a custom URL scheme:

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  openclaw-canvas://<session>/<path>

Examples:

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  openclaw-canvas://main/
  →
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  <canvasRoot>/main/index.html
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  openclaw-canvas://main/assets/app.css
  →
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  <canvasRoot>/main/assets/app.css
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  openclaw-canvas://main/widgets/todo/
  →
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  <canvasRoot>/main/widgets/todo/index.html

If no

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 is switched as needed).

Canvas can be disabled from Settings → Allow Canvas. When disabled, canvas node commands return

.

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
• capture a snapshot image

CLI examples:

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openclaw nodes canvas present --node <id>
openclaw nodes canvas navigate --node <id> --url "/"
openclaw nodes canvas eval --node <id> --js "document.title"
openclaw nodes canvas snapshot --node <id>

Notes:

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  canvas.navigate
  accepts local canvas paths,
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  http(s)
  URLs, and
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  file://
  URLs.
• If you pass
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  "/"
  , the Canvas shows the local scaffold or
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  index.html
  .

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:

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http://<gateway-host>:18789/__openclaw__/a2ui/

A2UI commands (v0.8)

Canvas currently accepts A2UI v0.8 server→client messages:

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  beginRendering
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  surfaceUpdate
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  dataModelUpdate
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  deleteSurface

(v0.9) is not supported.

CLI example:

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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

openclaw nodes canvas a2ui push --jsonl /tmp/a2ui-v0.8.jsonl --node <id>

Quick smoke:

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openclaw nodes canvas a2ui push --node <id> --text "Hello from A2UI"

Triggering agent runs from Canvas

Canvas can trigger new agent runs via deep links:

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  openclaw://agent?...

Example (in JS):

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window.location.href = "openclaw://agent?message=Review%20this%20design";

The app prompts for confirmation unless a valid key is provided.

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
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  http(s)
  URLs are allowed only when explicitly navigated.

Related

• macOS app
• WebChat