Preserve timestamp encoding in raw SQL predicates

When a background worker query interpolates date objects into raw SQL, verify the driver-bound parameter types. An ORM’s typed timestamp comparisons may encode dates while raw template parameters bypass that encoding, producing client-side serialization failures before any row can be claimed. Prefer typed comparison operators and test the compiled query or actual driver boundary; mocked query results alone do not validate serialization. A recurring worker failure can dominate a shared API error ratio even while interactive requests succeed, so assess impact by route and worker stage. This diagnosis applies only when nested error causes and the deployed query agree.