Production disproved the copy-from-batch approach in two ways:
- 10 delivery-note batches carry no file_hash at all (they predate
78fa8da), and all 10 sit inside the 30-day dedup window, so copying
would have left a live gap rather than a historical one
- one PO row was produced from two different files with different
hashes via the dedup-by-PO-number branch, so copying gives
last-write-wins on an arbitrary one
Hashing the stored bytes has neither problem and does not depend on the
collection we are about to delete. 56/56 records covered, none skipped.
Immediately surfaced a real duplicate the old path missed: two delivery
notes numbered IN132202 with identical bytes.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
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