Maker-Checker Loop
Use one agent to implement and another independent reviewer to check the result.
The handoff below was checked against the template boundaries: the checker stays read-only and a person keeps merge authority.
Practical evidence
Evidence handoff example
Scoped diff, failing-before and passing-after test output, commands run, and a short residual-risk note.
The regression test passes, but the diff also changes an unrelated timeout default outside the approved scope.
The maker removes the unrelated change, reruns the required checks, and returns a new evidence packet.
A person reviews the final diff, checker result, and evidence before approving merge or deployment.
What this Loop Engineering template does
Implement a change with a maker agent, then have an independent checker verify it before a human merges.
The checker must be a separate, read-only process from the maker. Human approval is required before merge.
When to use it
When not to use it
Validation checks
Boundaries & stop rule
Copy the loop prompt
/goal Implement a change with a maker agent, then have an independent checker verify it before a human merges.Task type: Code ReviewTarget tool: Claude CodeWork toward this goal until all validation checks pass or the stop rule is reached.Design hypothesis:This maker-checker loop can produce a safer result if the scope stays narrow, validation is explicit, and a checker can reject shortcut work.Smallest useful run:Run one bounded pass on the newest relevant signal before expanding scope or adding a schedule.Loop cycle:1. Discovery — Read the latest signal for this template before acting: CI output, issue detail, review comment, dataset report, or content brief.2. Handoff — Hand the work to one agent in an isolated branch, worktree, or clearly scoped session. Keep final approval with a human.3. Verification — Use an independent review pass to confirm the result, inspect the diff or artifact, and reject shortcut work.4. Persistence — Save a short run note with the signal reviewed, actions taken, validation result, and next recommended step.5. Scheduling — Run manually until the loop is reliable; only then consider a scheduled or event-triggered run.Context:The checker must be a separate, read-only process from the maker. Human approval is required before merge.Validation:Maker output passes testsChecker report is generatedBlocking issues are resolved or escalatedValidation evidence:Record the original signal, checks run, final result, changed files or artifacts, and any checker rejection.Independent checker:Use an independent review pass to confirm the result, inspect the diff or artifact, and reject shortcut work.Boundaries:Checker must not be the same process that made the changeChecker should be read-only unless explicitly authorizedHuman approval required before mergeStop rule:Stop when the checker passes and a human approves, or escalate if blocking issues remain after 3 maker-checker rounds.Maximum iterations: 4Budget:Example only: stop before exceeding the agreed per-run token budget.Human approval:Required before merge, deploy, delete, purchase, or external communication.Fallback:If maker and checker disagree, summarize both positions and escalate to a human.Loop Validation Log:- Hypothesis: This maker-checker loop can produce a safer result if the scope stays narrow, validation is explicit, and a checker can reject shortcut work.- Smallest useful run: Run one bounded pass on the newest relevant signal before expanding scope or adding a schedule.- Expected evidence: Record the original signal, checks run, final result, changed files or artifacts, and any checker rejection.- Actual evidence: [fill in after the run]- Passed? [yes / no / partial]- Feedback: After the run, note what the loop learned, what failed, and what should change before the next pass.- Next step: [stop / adjust the loop / run the next pass]Do not delete tests, bypass checks, or modify unrelated files just to satisfy the validation condition. If blocked, stop and summarize the blocker, attempted fixes, and recommended next action.
Failure modes to watch
Review receipt
This is a bounded review exercise for the template, not a claim about a production deployment.
Scenario
The maker claims a CI repair is complete after deleting the regression test that exposed the failure.
Baseline evidence
The checker receives the maker diff, before-and-after command output, original failing test name, declared boundaries, and merge authority separately from the maker's completion summary.
Validation result
Aggregate CI is green, but the checker returns Stop because required evidence disappeared; a corrected artifact restores the test, fixes the parser, and leaves merge to a person.
Shortcut rejected
Treating a green aggregate status as sufficient evidence is rejected when the exact regression test has been removed or weakened.
Human gate
A human reviews the independent checker findings and decides whether the corrected change may advance; neither maker nor checker can merge automatically.
Loop Engineering FAQ
A reviewer that shares the maker's context inherits its blind spots. Independence is what makes the check meaningful.