Bridge: any installed extension can connect without the token via a chrome-extension:// Origin #108

Summary

BridgeServer.attach() (packages/browser/bridge-browser/src/server.ts, the loopbackNoToken branch) grants the loopback bearer-token exemption to every Origin that starts with chrome-extension:// — not just this extension. Any other installed extension can open a WebSocket to ws://127.0.0.1:<port>/ext/bridge, send a tokenless hello, and drive the browser_* tools.

Pages cannot forge an Origin header, but any extension can present its own chrome-extension://<id> Origin, so the prefix check is not an identity boundary between extensions.

Impact

A malicious/compromised co-installed extension gains unauthenticated access to the bridge (prompt/approval flows still apply, but the auth layer is bypassed). This becomes more relevant if #100 widens connect-src for remote bridges.

Suggested fix

• Replace the prefix check with an exact-match allowlist of extension origins.
• Ship a stable manifest key so this extension's Chromium id is deterministic (path-independent), and pin that single origin by default.
• Keep the token path for everything else (Firefox moz-extension:// UUIDs, custom builds, non-loopback clients); make the list configurable for forks.