The DAO swallowed every diesel::update failure as a flat
`anyhow!("Update error")`, then trace_db_call further reduced it to
`DbError { kind: UpdateError }`. Operators saw "update failed for lib
2 Snapchat/foo.mp4: DbError { kind: UpdateError }" with no clue why
(constraint violation? type mismatch? row vanished mid-flight? DB
locked?).
Two changes:
- Preserve the diesel error in the anyhow chain along with the input
params (lib, rel_path, date_taken, source) so the cause is visible.
- Log the chain at warn-level inside the DAO before the trace wrapper
collapses it to DbErrorKind::UpdateError, so the warning at the
call site finally has something diagnosable next to it.
- Treat zero-row updates as a debug-level "row likely retired by the
missing-file scan" rather than a hard failure — that case is benign
and shouldn't poison the drain's error tally.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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