Keep API contract changes visible in a pull request packet

Is the handoff ready?

Use these checks before access expands or the first ticket begins.

Make the contract change explicit

An API contract change should be visible in the pull request title, the ticket. The changed files. The reviewer should not have to infer it from a modified response fixture. State which request fields, response fields, status codes, headers, or error shapes changed and which consumers are affected.

If the change is additive, say so and explain why existing clients remain compatible. If it is breaking, name the versioning or migration path. A contract change that is hidden inside a refactor is a review failure even when the code works for the current client. That check belongs in the make the contract change explicit note, with the owner and the next action visible.

Link the consumer evidence

The author should identify the applications, jobs, or external clients that call the endpoint and link the evidence that they still work. That evidence may be an integration test, a contract test, a staging request, or a documented consumer inventory. A green unit test on the server does not prove that a mobile client still parses the response. The link the consumer evidence record should be dated and linked so a second reviewer can reproduce the result.

If the consumer list is incomplete, record the uncertainty and the plan to verify it. Do not claim that no other consumers exist because the repository search found none. External integrations and cached clients can outlive the code search. That check belongs in the link the consumer evidence note, with the owner and the next action visible.

Show the error path

API changes often alter the error shape or the conditions that produce it. The pull request should show how validation failures, authorization failures, rate limits. Upstream timeouts appear to the caller. Include the status code and the response body for at least one failure case.

A reviewer who sees only the happy path cannot judge whether a client will handle the new error correctly. If the error contract is unchanged, say that explicitly and point to the test that proves it. The expected behavior should be written before the implementation is reviewed. That check belongs in the show the error path note, with the owner and the next action visible.

Record the review against the commit

Approve the exact commit that contains the contract change, not an earlier branch state. If the author pushes again after approval, the approval should be renewed or the new diff should be reviewed. A contract change can be small enough to miss in a later push, especially when the pull request already has many comments. The record the review against the commit record should be dated and linked so a second reviewer can reproduce the result.

Use the repository review record to capture the approval and any follow-up. Link the contract test result to the same commit. The reviewer should be able to answer which version of the API was approved and when, without reading a chat history. That check belongs in the record the review against the commit note, with the owner and the next action visible.

Plan the rollout and rollback

A contract change may need a staged rollout, a feature flag, or a deprecation window. Record the sequence and the condition for expanding the change. If the new behavior causes a consumer failure, name the rollback action and the person who can execute it. The plan should be proportionate to the number of consumers and the consequence of failure.

For a breaking change, the rollback may be a version switch rather than a code revert. Record that distinction so the responder does not choose the wrong path. The client owner should approve the rollout plan, not only the code. That check belongs in the plan the rollout and rollback note, with the owner and the next action visible.

Close with a compatibility check

After release, verify that the expected consumers still work, that the error path behaves as documented. That monitoring shows no unexplained change. Record the check time and the evidence. If a consumer fails, preserve the request and response details and route the issue through the rollback plan.

The check should also confirm that the documentation and client examples match the released contract. A stale example can create the same failure as a code defect. Add the finding to the next review so the contract process improves. That check belongs in the close with a compatibility check note, with the owner and the next action visible.

Document the client migration path

For a breaking change, write the steps a client must take before the old behavior is removed. Include the new field or endpoint, the compatibility period, and the date the old path will stop working. A migration guide that says update your client is not a plan. The document the client migration path record should be dated and linked so a second reviewer can reproduce the result.

If the client controls the rollout, record who will communicate the change and how the team will confirm adoption. A deprecation window without a named owner tends to expire quietly. The review should show that the consumer has a realistic path, not only that the server supports a new shape. That check belongs in the document the client migration path note, with the owner and the next action visible.

Check the contract after release

After deployment, verify the live response against the documented contract and the expected error behavior. Record the check time and the evidence. A contract test that ran before release is useful, but it does not prove that the deployed service is serving the approved shape. The check the contract after release record should be dated and linked so a second reviewer can reproduce the result.

If a mismatch appears, treat it as a release issue and use the rollback plan rather than patching the documentation to match. The post-release check should also confirm that monitoring sees the new behavior and that no unexpected consumer errors appear. That check belongs in the check the contract after release note, with the owner and the next action visible. The check should be repeated after any follow-up deployment that changes the contract.

Keep the contract test reproducible

A contract test should be runnable by someone other than the author. Document the command, the environment, and the fixture or sandbox it needs. A test that only works on one laptop is not strong evidence for a release that other people must support. The keep the contract test reproducible record should be dated and linked so a second reviewer can reproduce the result.

Record the exact version of the test and the service it exercised. If the test depends on external state, note that and describe how the state was prepared. The reviewer should be able to rerun the check when the change is questioned later. That check belongs in the keep the contract test reproducible note, with the owner and the next action visible.

Frequently asked questions

Sources

1. OpenAPI Specification

   Provides a machine-readable contract format for review and testing.

2. NIST SP 800-218, Secure Software Development Framework

   Supports review and verification of software changes.

3. GitHub Docs: About pull request reviews

   Supports approval tied to a specific commit.