Probe whether the code/Serena tunnel slot is ready for this project.

Called by the code_intel_guard hook after it confirms code_intel_enabled=1. Performs an actual tools/list round-trip to the code slot (which wakes up an idle-killed Serena daemon via the tunnel's lazy-spawn mechanism) and returns the readiness result.

Response shape: { "slot": "code", "ready": bool, # True when the slot answered tools/list "has_tunnel": bool, # False on self-hosted (no tunnel = fail-open) "probed": bool, # True when a live probe was attempted "fallback_reason": str # present only when ready=False (visible log hint) }

Fails open (ready=true, has_tunnel=false) when no tunnel is connected so the hook never blocks an executor that has no tunnel (the enabled flag is still the primary gate; this is only a secondary readiness gate).