The actual HiFi/Monochrome bug isn't silence padding — it's a TRUNCATED file:
the container claims the full length (e.g. 3:08) but only ~30s of audio
decodes. silencedetect finds nothing (there's no silent audio, just missing
audio) and ffmpeg's time= even reports 0 with no error, so the duration and
quality guards all pass.
Detect it by decoding and comparing the real audio length (astats sample
count / sample rate) against the container duration: reject when the real
audio covers < 85% of the claimed length. detect_broken_audio() runs this
truncation check first, then the silence-ratio check. Wire it into the guard
that runs at the integrity/length verification point.
Verified on the real file: 'only ~30s actually decodes of a 188s file (16%)';
a normal 180s file is not flagged.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
HiFi/Monochrome HLS assembly can produce a file with the correct container
duration but only ~30s of real audio + silence padding — the duration and
quality guards both pass, so nothing caught it until you listened. Add
core/imports/silence.py: ffmpeg silencedetect over the audio, reject when the
silent fraction exceeds 50%. Wire it into the post-download pipeline with the
same quarantine + next-candidate retry pattern as the quality guard
(trigger='silence'), and surface it via import_rejection_reason. Fails open
when ffmpeg/mutagen are unavailable so tooling problems never quarantine a
legit file.
Also mark 'quality filter' and 'silence guard' failures as recoverable
quarantine rows in the downloads UI (were shown as plain failures).
Verified end-to-end: a 30s-tone + 180s-silence FLAC is flagged '86% silence
(only ~30s audible of 210s)'; a 210s tone passes. 7 parser unit tests.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
