The reconciliation job — trust, but verify

Every pattern so far can lose data quietly: a dropped event, a skipped row, a retry that gave up. Each loss is rare; across a year they are a certainty.

The reconciliation job is the answer, and it is gloriously boring: every night, count and sum both sides for the previous day, compare, and raise a case on any mismatch. This lesson builds it as a Batch Apex job, tunes the comparison window around timezone edges — where every reconciliation bug lives — and finishes the course with the claim the whole thing has been building to: an integration is not done when it works; it is done when you would know if it stopped.