Found by ChatGPT Codex reviewing PR #150 at af7fae0e, and correct. The tally was
incremented while walking a record's categories, before the record was known to
survive that walk. A row whose Date is unparseable and whose LATER required
category is missing is skipped entirely — it never lands in the imported model —
yet it had already been charged to the derived column. So the warning counted a
row nothing else in the import reports, and its value depended on the order the
categories happen to be walked in.
Mismatches are now collected per record and merged only after missing.is_none().
The regression asserts the fixture's category order explicitly, because it only
discriminates while Date precedes the missing category: a later change to
proposal order would otherwise make the test pass by never reaching the bad
date. Before the fix it reports three warnings where one is correct; the rival —
merging before the missing check rather than after — reproduces exactly that.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01FC2jVn8Au7E9JPkw6bwXXH
Edward Langley
d7ae99722b