OpenClaw integration is blocked by missing Chromium-style discovery endpoints (/json, /json/list, /json/protocol) despite successful CDP connect and navigation

[Cyrillico]

Summary

We tried integrating Lightpanda as a remote CDP browser backend for OpenClaw and found the following behavior:

• Lightpanda CDP server starts successfully
• /json/version is available
• OpenClaw can connect successfully and can perform a basic open <url> navigation
• However, most browser control operations used by OpenClaw fail afterwards with HTTP 404

The blocker appears to be strongly related to missing Chromium-style discovery endpoints, especially:

• /json
• /json/list
• /json/protocol
• /json/new?...

All of these return 404 on the current Lightpanda server, while OpenClaw’s current browser stack appears to rely on at least part of this discovery / target enumeration behavior.

So at the moment Lightpanda can be “partially connected”, but cannot be used as a drop-in backend for OpenClaw’s existing browser control stack.

Environment

• Lightpanda: lightpanda/browser:nightly Docker image
• Platform: macOS arm64
• OpenClaw: local gateway/browser control
• Transport: remote CDP via ws://127.0.0.1:9222

Reproduction

1. Start Lightpanda

docker run -d --name lightpanda-test -p 9222:9222 -e LIGHTPANDA_DISABLE_TELEMETRY=true lightpanda/browser:nightly

Container logs show:

server running address=0.0.0.0:9222

2. Check discovery endpoints

curl http://127.0.0.1:9222/json/version

Response:

{"webSocketDebuggerUrl":"ws://0.0.0.0:9222/"}

But the following endpoints return 404:

curl http://127.0.0.1:9222/json
curl http://127.0.0.1:9222/json/list
curl http://127.0.0.1:9222/json/protocol
curl 'http://127.0.0.1:9222/json/new?https://example.com'

3. Configure a remote CDP profile in OpenClaw

For example:

{
  browser: {
    profiles: {
      lightpanda: {
        cdpUrl: "ws://127.0.0.1:9222"
      }
    }
  }
}

4. Run tests

These commands succeed:

openclaw browser --browser-profile lightpanda status
openclaw browser --browser-profile lightpanda open https://example.com

But the following commands all fail with HTTP 404:

openclaw browser --browser-profile lightpanda tabs
openclaw browser --browser-profile lightpanda snapshot
openclaw browser --browser-profile lightpanda snapshot --interactive
openclaw browser --browser-profile lightpanda screenshot
openclaw browser --browser-profile lightpanda evaluate --fn '() => document.title'
openclaw browser --browser-profile lightpanda wait --text 'Example Domain'

Actual result

• CDP server is running
• /json/version works
• Navigation works
• But tabs / snapshot / screenshot / evaluate / wait all fail with HTTP 404

Expected result

Either of the following would help integration significantly:

Option A

Implement Chromium-style discovery endpoints, at least:

• /json
• /json/list
• /json/protocol

This would make it easier for existing CDP/browser clients like OpenClaw to reuse their current discovery logic.

Option B

If these endpoints are intentionally not supported, it would help to document clearly that:

1. Chromium-style /json/* discovery is not currently supported
2. Recommended integration should use:
   • persistent WebSocket connection
   • Target.createTarget
   • Target.attachToTarget
   • avoid relying on /json/list
3. What the recommended stable target discovery / current-page attach pattern is

Related issues

We found a couple of related issues that suggest this is not an isolated case:

• Playwright connectOverCDP fails: frame ID mismatch in Page.getFrameTree (startup path) #1800: Playwright connectOverCDP fails: frame ID mismatch in Page.getFrameTree (startup path)
• Integration: Neo CLI works with Lightpanda as headless backend #1908: Integration: Neo CLI works with Lightpanda as headless backend

Issue #1908 in particular mentions that:

• /json/list is not implemented
• they work around it via Target.createTarget + Target.attachToTarget
• which suggests the core CDP functionality is usable, but differs from Chromium’s default discovery model

Questions

Could you clarify:

1. Is the absence of /json, /json/list, and /json/protocol expected behavior?
2. Are there plans to implement these endpoints for better compatibility with existing Chromium-oriented CDP clients?
3. If raw CDP attach is the recommended integration path, would you consider documenting that more explicitly in the README / docs?