dropped_chunks was incremented on cpal-callback channel-full and
validation requeue overflow but never read by the live session, so
the UI's dropped_audio_ms missed callback-level losses entirely.
Architecture doc had flagged this as a TODO. Also: the 350ms
validation buffer was requeued via try_send into the same 32-slot
channel, silently dropping past the cap on small-buffer audio hosts
(WASAPI exclusive, low-latency ALSA at 256 frames -> ~65 chunks).
Fix: live runtime reads MicrophoneCapture::dropped_chunks() on each
recv_audio tick (LiveSessionRuntime::poll_capture_drops) and converts
the per-chunk-duration delta into the dropped_audio_ms surfaced to
the UI overload status. Per-chunk duration is derived from the most
recent AudioChunk's sample_rate + samples-per-channel so it adapts
to whatever rate cpal is delivering at. Validation requeue moved
from try_send into the bounded channel onto a VecDeque<AudioChunk>
returned alongside the Receiver; ActiveCapture drains the replay
buffer before reading rx in recv_audio, bypassing the 32-slot cap
entirely. Architecture doc updated to remove the TODO and document
the new pre-roll path.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Jake
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