SpeechTimeoutUserTurnStopStrategy previously collapsed two waits into
max(stt_timeout, user_speech_timeout), which over-waited for finalizing
STT services and could also end the turn early in a legacy code path.
Run them as independent timers instead:
- user_speech_timeout: policy floor, always runs to completion.
- stt_timeout: latency safety net, short-circuited by a finalized
transcript since STT has signaled it has nothing more to send.
The no-VAD fallback now waits only user_speech_timeout rather than
max(stt_timeout, user_speech_timeout); stt_timeout is defined relative
to VAD stop and has no meaning when no VAD event occurred. This
shortens the fallback wait for users who set stt_timeout greater than
user_speech_timeout.
When the STT p99 timeout fires without a transcript, the turn stop
strategy previously did nothing — falling through to the 5-second
user_turn_stop_timeout. Now, a _timeout_expired flag tracks when the
timeout has elapsed so that a late transcript triggers the turn stop
immediately instead of waiting for the fallback.
Add warnings in SpeechTimeoutUserTurnStopStrategy and
TurnAnalyzerUserTurnStopStrategy when stop_secs differs from the
recommended default (0.2s) or when stop_secs >= STT p99 latency,
which collapses the STT wait timeout to 0s. Document the stop_secs=0.2
assumption in stt_latency.py.
Reset stop strategies at turn start (not just turn stop) so that late
transcriptions arriving between turns do not leave stale _text that
causes premature stops on the next turn. Also cancel pending timeout
tasks in reset() for both SpeechTimeout and TurnAnalyzer strategies.
Refactor TranscriptionUserTurnStopStrategy and TurnAnalyzerUserTurnStopStrategy
to use VADUserStoppedSpeakingFrame as the ground truth for when speech ended,
rather than triggering timeouts from transcription frames.
