Idempotency and Atomicity

Backlog field	Value
Story ID	CTRL-005
Epic	Cross Cutting Controls
Story type	Transaction control
Review status	Draft - business analyst and business owner review required
Source evidence	Draft-only posting checks, SaveToContext boundaries, unit of work, source IDs, external identifiers
Last source review	2026-07-10

As a finance owner, I want Post and integration retries to apply their business effect no more than once and all linked effects to succeed or fail together.

Acceptance scenarios

Duplicate Post on a non-Draft document is rejected. Commercial journal, stock, payment, balances, credit, source status, and audit commit atomically. External retries use stable external identity. Partial failures do not leave one linked leg effective.