http-api-openapi

Use this skill when

• The task adds or changes a public HTTP endpoint and the OpenAPI contract must stay aligned.
• Request/response schemas, status codes, auth requirements, or documented errors are changing together.
• Code and API contract have drifted and the repo needs the correct sync workflow.

Do not use this skill when

• The request is a generic REST/OpenAPI tutorial.
• The task is only to generate a client SDK from an existing spec with no server-contract change.
• The change is internal-only code with no HTTP contract or no OpenAPI surface in play.

Inputs to gather

• Where the API contract lives:
  • hand-authored spec files
  • code annotations/types/routes that generate the spec
  • a hybrid flow that updates both
• Validation/generation commands for the repo (make validate-openapi, swagger-cli, codegen targets, etc.).
• The exact endpoint surface being changed: path, method, auth, request body, success responses, error responses.
• Whether the endpoint is public/external, internal-only, or intentionally undocumented.

First move

Determine the repo's contract flow before editing anything: spec-first, code-first, or hybrid. Do not assume openapi.yaml is the source of truth or that it should be hand-edited.

Workflow

1. Identify the contract owner.

   • Read the repo docs, build targets, and generation tooling to see whether the spec is hand-maintained, generated from code, or maintained in both places.

2. Follow the repo's contract path.

   • Spec-first repos: update the OpenAPI contract first, validate it, then implement handlers/middleware/tests to match.
   • Code-first repos: update the handler/types/annotations first, regenerate the spec/artifacts, then verify the generated contract matches the intended behavior.
   • Hybrid repos: update both authored surfaces in the order the repo expects, then run validation/generation to reconcile them.

3. Verify the behavior-contract alignment.

   • Match auth requirements, request validation, response schemas, status codes, and documented error shapes.
   • Confirm the changed endpoint is included or intentionally excluded from the OpenAPI surface.

4. Run the repo's API checks.

   • Validate the spec when the repo has a validator.
   • Run the relevant integration/unit/contract tests for the changed surface.

Outputs

• Updated contract-owner artifacts for the changed API surface, including spec, handler/type inputs, and any generated OpenAPI output the repo expects.
• A documented behavior-to-contract alignment for auth requirements, request validation, response schemas, status codes, and error shapes.
• Spec validation, generation, and/or API test evidence confirming the handler behavior and OpenAPI contract stay in sync.

Guardrails

• Do not hand-edit generated OpenAPI output in code-first repos; change the source inputs that own it.
• Do not change public endpoint behavior without the matching contract update or regeneration.
• Auth requirements, status codes, and error shapes must align with the contract owner the repo actually uses.
• If the repo has no OpenAPI contract for this surface, do not invent one unless the user asks for that design decision; document the gap instead.
• When handler changes also affect generated clients/server stubs, coordinate with the code-generation workflow rather than patching generated artifacts directly.

Validation

• The repo's spec validation or generation step succeeds.
• Handler behavior, tests, and contract artifacts agree on auth, schemas, and status codes.
• Any generated contract files or checked-in specs show only the expected diff.

Support files

• Read references/examples.md when you need examples of drift repair or endpoint changes that must keep contract and implementation aligned.
• Read references/edge-cases.md when the repo lacks a spec, uses generated specs, or the request may really be SDK generation or a non-HTTP change.