Previously hardcoded at 3s (5s for tracks >10min) — files drifting
past that got quarantined with no user override. Live recordings,
alternate masterings, and some legitimate uploads routinely drift
further.
New setting `post_processing.duration_tolerance_seconds`. Default 0
means "use auto-scaled defaults" (unchanged behavior for users who
don't touch it). Positive value overrides the per-track defaults.
Capped at 60s — past that the check is effectively off.
Logic lifted to pure helper `resolve_duration_tolerance` in
file_integrity.py. Coerces every plausible input (None / empty /
zero / negative / unparseable / above-cap / numeric string / float)
to either a float override or None for auto. 12 tests pin every
shape.
Wired into `core/imports/pipeline.py` at the integrity-check call
site — runs for ALL matched downloads (Soulseek / Tidal / Qobuz /
HiFi / YouTube / Deezer-direct) since they all share that pipeline.
Settings UI input under Settings → Metadata → Post-Processing.
