Daemon crashes on startup with Chrome 151: "data did not match any variant of untagged enum Message" #61

Summary

On Windows 11 with Chrome 151, the gsd-browser daemon dies during startup. The Rust CDP message deserializer rejects messages emitted by this Chrome build, so every MCP browser_* tool and the gsd-browser CLI (navigate / set-viewport / etc.) hangs or crashes. There is no working session.

Environment

• @opengsd/gsd-browser: 0.2.2 (latest published)
• Chrome: 151.0.7922.170 (C:\Program Files\Google\Chrome\Application\chrome.exe)
• OS: Windows 11 Home 26200
• Node: >=16

Symptoms / logs

Daemon startup logs the following, then exits:

WARN WS Invalid message: data did not match any variant of untagged enum Message
daemon exited during startup with status exit code: 1

The first line points at the untagged-enum CDP Message deserializer failing to match a frame from Chrome 151. The daemon then terminates with exit code 1 before it is ready, so no browser session is ever established.

Additional observation (may be a second, separable issue)

Loopback fetches from the controlled browser are refused with:

localNetworkAccessRequestPolicy: PermissionBlock

Chrome 151 enforces the Local Network Access permission gate; automating http://localhost:* targets requires the LocalNetworkAccess check to be disabled on launch. Worth surfacing in docs even independent of the deserializer crash.

Impact

Complete loss of the tool surface on this machine — no MCP browser tools and no CLI navigation are usable against Chrome 151.

Workaround in use

Bypassing the daemon entirely: launching headless Chrome with --remote-debugging-port=9222 (and LocalNetworkAccess checks disabled) and driving it over a raw CDP WebSocket from a small Node script. Functional, but a parallel path rather than a fix.

Likely root cause

The untagged Message enum in the daemon's CDP deserializer doesn't cover a message shape/variant introduced (or changed) in Chrome 151's protocol output. A tolerant/#[serde(other)]-style fallback, or updating the protocol schema to Chrome 151, would likely resolve it.