Two repository-guide violations raised in review on #7570.
Selection is what this fix changes, but the regression test seeded only the
producer being retired. It now seeds a sibling approval on the same run and a
producer belonging to an unrelated run, then asserts the target is consumed,
both survivors remain queued, and reconciliation does not resurrect the denied
approval's mirror. Mutation-checked so the new assertions have teeth: an
over-aggressive filter that retires every same-run entry fails on the sibling
assertion, and the unfixed implementation fails on the target assertion.
Runtime behaviour also changed without tracked documentation of the invariant.
The api/route_approvals.py module docstring now records the producer/mirror
ownership direction and the retirement rules, including why an unattributable
same-run producer is retired with its run.
Additive commit: the previous commit is published and under review, so the
reviewed history is preserved rather than rewritten.
Michael Snoyman
571ef3eec2