01 / What each boundary answers
Compare the decision, not the label.
Lets an accountable reviewer approve a specific proposed action when judgment or separation of duties is required.
Checks request parameters, approval binding, expiry, current grant and execution constraints at the effect boundary.
02 / Same operating case
Which request must be stopped?
A reviewer approves a $9,000 vendor payment; the agent later changes the payee.
Evaluation exercise
Approve a canonical payment request and alter one byte of the payee account before execution. The executor should reject the approval digest rather than trusting the reviewer event alone.
03 / Architecture fit
How the controls can compose
Route exceptional decisions to people, then bind their approval to an immutable action digest and enforce it in code.
Human review is not a substitute for technical prevention of replay or parameter changes.
04 / Evidence
Prove the decision and the effect separately.
Reviewer, displayed proposal, approval digest, current policy decision, payment attempt and settlement.
Primary sources