A successful finalize edit can carry only the last streamed preview
snapshot: deltas generated between the last preview edit and stream
completion never reach any Bot API call, yet final_response_sent /
final_content_delivered were set from the call's success and suppressed
the gateway's normal final send — losing the tail permanently.
The stream consumer now records the exact cleaned payload of every
turn-final delivery (delivered_final_matches tri-state), and gateway/run.py
reconciles that record against the completed final_response before
trusting either suppression flag. On a demonstrable mismatch it edits the
streamed message up to the complete response, falling back to the normal
final send if the edit fails. Multi-message split deliveries and legacy
paths without a record keep the existing flag-trusting behavior, so
overflow splits and the failed-finalize handling (#51828/#33793) are
untouched.
Fixes#71643
Teknium