@traced_stt had the same root issue as @traced_tts: the span lifetime
was tied to a per-transcript handler call, which doesn't match the
operation we want to trace. Now uses the __set_name__ pattern to
install:
- A push_frame wrapper that drives one STT span per finalized
TranscriptionFrame. The span is anchored at speech start
(VADUserStartedSpeakingFrame.timestamp - start_secs) but lazy-opened
on the first TranscriptionFrame. Opening earlier (on VAD or
UserStartedSpeakingFrame) races with TurnTraceObserver._handle_turn_started,
which runs as a background task via _call_event_handler (sync=False),
so the span would end up parented to the previous turn. Deferring
the open to the first TranscriptionFrame avoids that race because
STT only emits transcripts well after the turn observer has set
the current turn's context.
- A stop_ttfb_metrics wrapper that closes the span on the TTFB-timeout
path (called with end_time != None from stt_service.py:566). The
span is marked stt.timed_out=True and its end_time is pinned to
the timeout's end_time (= _last_transcript_time) so the duration
reflects when STT actually stopped responding, not when the timeout
fired.
Span lifecycle:
- Open: lazy on first TranscriptionFrame of a segment.
- Close (success): finalized=True attaches metrics.ttfb and closes
the span. Multiple finalized transcripts in a single turn produce
multiple spans.
- Close (timeout): stop_ttfb_metrics(end_time=...) closes with
stt.timed_out=True.
- Close (orphan): UserStoppedSpeakingFrame closes any still-open
span with stt.incomplete=True (covers turns where no finalized
transcript and no timeout fired).
No changes required outside service_decorators.py — stt_service.py
and every per-service file are untouched.
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