The MailPruner/MailBackfiller unit tests mock the DAO, so the queries that
actually define the device-only retention floor were never exercised against a
real database: the newest-N-by-(timestampMillis, uid) prune selection, the
strict age cutoff, the windowed reconcile that spares backfilled history, and
the lowest-uid / count / oldest floor probes the backfiller stops on.
Add an instrumented MessageDao test on an in-memory Room DB covering all of
them, including the timestamp/uid tie-break direction (a flipped ORDER BY would
locally delete the user's newest mail) and inInbox/folder/account scoping.
This closes the disjoint-sets safety argument at the SQL-boundary level, not
just the orchestration level. Verified on the API 37 emulator (5/5).
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
JMR-devandClaude Opus 4.8
ec60348c89