Surface which Chrome profile / DISPLAY / CDP port the live FSB session is bound to

[Trace824]

Summary

Operators debugging attach issues cannot see which Chrome profile, DISPLAY, or remote-debugging port the live FSB bridge session is bound to. CDP port vs DISPLAY mismatch (e.g. Chrome on one display while scripts expect another) is hard to diagnose.

Repro

• Context: Multiple Chromes / displays; MCP connected via hub :7225 or HTTP :7226.
• Steps:
  1. Connect MCP; call health / list_tabs / a no-op tool.
  2. Attempt to determine profile path, DISPLAY, and --remote-debugging-port from FSB alone.
• Observed: no first-class session metadata; mismatches discovered only via OS process inspection.

Code pointers (verified against /workspace/FSB)

• mcp/src/bridge.ts — hub/relay connection state.
• mcp/README.md — http://127.0.0.1:7226/health.
• mcp/src/native-host/constants.ts — NATIVE_HOST_SERVICE_PORT = 7226.
• Likely area: extend health or a read-only diagnostic tool with extension-reported environment hints (no invented fields until designed).

Proposed fix

Expose read-only session diagnostics (health or tool): extension id/instance, whether a window exists, optional user-agent/profile label if available, and bridge mode (hub vs relay). Document that OS DISPLAY/CDP ports are operator concerns unless exposed by the launcher.

Acceptance / regression

• Health or diagnostic output identifies which extension connection is active.
• Docs describe how to map that to profile/DISPLAY in local setups.

Owner

mcp-server (+ extension metadata)

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Priority: P2 · Owner: mcp-server