Deep-review round 1 found the new tests asserted end-state only, so both
safety mechanisms this change adds were untested (a regression would ship
green):
- Per-page cursor durability: add test_a_mid_run_failure_leaves_the_prior_page
_durably_committed, which fails the 2nd page's fetch after page 1 committed
and asserts the cursor + rows are already persisted (re-read via db.expire).
Mutation-verified: reverting to a single end-of-loop commit makes it fail
while the pre-existing paging tests stay green — the property the original
test could not distinguish.
- Reserve guard: add test_backfill_reserve_reached_tracks_the_boundary, driving
real record_usage spend across the 9000/2000 default boundary and asserting
the un-mocked quota.backfill_reserve_reached() flips at exactly remaining<=reserve.
Full backend suite: 244 passed, 2 skipped (network-gated).
peter
ee2bd81254