Offline-first in Flutter works when the UI only ever reads from the local Drift database, and every write goes into that database along with an outbox row in the same transaction. A background worker then sends the outbox to your API with idempotency keys. Last-write-wins settles conflicts for most fields, and explicit merge rules cover the few fields where a blind overwrite would throw away someone's work. Below is a version of that design you can read in one sitting, plus the tests that cat...