Deep-review round 3: the only surviving finding — a comment-drift nit. The
fallback's cull-yield comment named the route's 'Not available yet' path, but a
culled-key segment request actually returns 'No active playback session' (the
substantive invariant — never a None that 404s as file-not-found — is unchanged).
Reworded to match the route. Concurrency + correctness came back clean.