review-loop — the independent adversarial loop

Nobody grades their own exam. The maker implements, a separate fresh checker tries to break the claim, and the two alternate until the checker approves the code as it stands right now.

When this applies

Any change to behaviour: executable code, shell/Python/JS/TS/SQL, CI/CD, hooks, commands, agent and skill definitions, runtime prompts, and configuration that changes what the system does.

Exempt: prose documentation, marketing copy, typos, and formatting that cannot change behaviour. When a documentation-only change also touches something a runtime reads, it is behavioural. If you are unsure which side a change falls on, treat it as behavioural.

File count and diff size are not exemptions. A one-line change to an authorization check is behavioural; a 900-line documentation reflow is not.

Risk	Lanes required
Ordinary behavioural change	1 independent checker
Auth, authorization, payments, access-control rules, secrets, destructive data changes, irreversible deploys	2 lanes, run by different checkers: correctness plus the risk-specific angle (runtime security, or rollback)

The loop

maker implements → targeted test / real-surface QA → fresh checker
     ↑                                                    │
     └────────── REQUEST_CHANGES ← findings ──────────────┘
                                                          │
                                          APPROVE on current code → done

There are exactly three verdicts: APPROVE, REQUEST_CHANGES, UNVERIFIED.

• APPROVE is a completion candidate only when it was issued against the revision that is checked out now, with evidence produced from that same revision.
• REQUEST_CHANGES means the maker fixes the findings surgically, re-runs the tests, and calls a fresh checker again. Fixing more than the findings restarts the argument.
• UNVERIFIED means no judgement was reached: the checker never ran, returned empty, timed out, errored, was rate-limited, returned a malformed envelope, or reviewed a state that has since moved. It is not a pass. Retry with a different checker, runtime, or strategy.

If a checker modifies the source, it has joined the maker set and its verdict is void. A past maker can never be that change's checker.

Running it

1. Implement. Keep the change inside the scope you declared. Unrelated cleanup that arrives in the same diff will be reviewed as part of it.

2. Produce evidence before dispatch. Run the targeted tests and, when the change has a surface a person uses, exercise that surface the way they would. Record the exact commands and their exit status. Evidence from before your last edit is stale.

3. Dispatch a fresh checker. Use the Task/Agent tool to spawn adversarial-reviewer in its own context, or a general-purpose agent given that agent's contract. Hand it:

   • the goal and acceptance criteria in one paragraph,
   • the scope (paths, or the diff range),
   • the commands you ran and what they returned,
   • the revision under review (git rev-parse HEAD).

   Do not hand it your conclusion. "I verified this works" is the claim under test, not context.

4. Read the verdict, not the tone. A checker that praises the change but lists a HIGH finding has returned REQUEST_CHANGES. A checker that died mid-run has returned UNVERIFIED, however encouraging its last message was.

5. Fix and re-dispatch. Every round gets a checker with a fresh context. Reusing the previous checker means asking someone to re-read their own conclusion.

6. Stop when a current APPROVE exists for the code as it stands, backed by evidence from that same revision.

Re-verification etiquette

When you come back for round N+1, say so plainly:

• state what changed since the last round, in one or two lines, and name the finding each edit addresses;
• ask the checker to re-reproduce the original defect, not to take your word that it is gone;
• explicitly invite it to attack the fix itself. Fixes introduce their own defects, and a fix written under review pressure is exactly where a second one hides.

Both of the defects worked through in docs/VERIFICATION-LOOP.md were found this way: the first review broke the guard, and the review of the fix broke the fix.

When rounds stop converging

Three rounds on the same strategy is not a reason to stop, and it is not a reason to keep going unchanged. Switch strategy: a different reproduction, a narrower test, a different checker or runtime, or a re-plan of the approach. See references/convergence-detection.md.

Escalate to the human when the same finding comes back REQUEST_CHANGES twice in a row: two failed attempts at one defect means the diagnosis is wrong, and a third attempt usually makes it worse. Report the finding, both attempted fixes, and the reproduction. See rules/adversarial-review.md.

Never report success when

• the reviewed revision is not the revision that is checked out now;
• there is no successful evidence from after the last edit;
• the checker was the maker, or a fork of the maker's context;
• a required lane is missing;
• the checker modified code, returned an empty or malformed verdict, or timed out;
• you are reusing an APPROVE from a different change or a different session.

In every one of those cases the honest report is what is missing, not "done".