Trigger automatic speaker-to-face matching in suggestions mode.

Same body, auth, and prerequisites as POST .../speaker-face-match, but does not write face.speaker_id, face.accuracy, or face.personality_traits. The worker (or a fully-resolved name-channel pre-pass) stores an advisory block on video.speaker_face_match.suggestions that the client commits verbatim through the existing PUT.

Poll GET .../statuses?speaker_face_match_status=true. The stored in-flight value is "queue" (the trigger response status is "processing"); a finished suggest run writes "completed" or "failed". GET .../speaker-face-match/suggestions returns 404 when no block exists. Stop polling when the statuses states.speaker_face_match_status.terminal flag is true, including failed with speaker_face_match_reason: "timed_out".

No eligible speakers in the requested scope completes immediately with items: [] and leaves bindings and personality unchanged. reason: "no_speakers" is included only when the whole audio has no eligible speakers. Pending transcript replacement returns 409.

Returns 409 if a non-stale run is already in flight (status=="queue" and queued_at within 15 minutes). queued_at is stamped only on suggest-mode triggers. A historical or commit-mode "queue" with no queued_at (commit-mode write-back never terminals that field) is treated as stale and does not 409.

A commit-mode POST issued while a suggest run is in flight also 409s, so an impatient click cannot convert the in-flight preview into a personality- wiping commit. After the stale window that 409 lifts, a late suggest-era worker PUT .../matched_speakers can still arrive. If a commit POST has already cleared mode (and possibly personality), that late PUT takes the commit branch and mutates faces[] with the old preview's matches. There is no run-id on the worker contract to ignore it.

Error Responses

• 401 Unauthorized: User is not authenticated or not authorized to access this video
• 404 Not Found: Video not found
• 409 Conflict: Video or audio processing not completed, or a match run is already in flight
• 400 Bad Request: Audio ID missing in video document, target_speaker_ids is an empty list, or target_speaker_ids contains a speaker ID not present in the audio
• 422 Unprocessable Entity: Request body includes the removed target_face_ids field