HTTP Status Code

Outcome: Design or review HTTP Status Code for this system while keeping data correct, secure, and easy to operate. User context: An import API returns 202 and a status URL while work continues. It returns 201 with `Location` after an immediate creation. It returns 409 for a version conflict and 422 for CSV fields with invalid meaning. A JSON problem body adds useful details without changing what the code means. Technical concept or control: HTTP Status Code. Why it fits: Return the most exact registered code that fits the result. Add useful headers and a stable error body when needed. Do not use it when: Do not return 200 for every business failure. Also avoid errors so specific that they reveal secret authorization details. Engineering requirements: Define inputs, outputs, contracts, and rules that must always hold. Set authorization and input checks. Define failures, timeouts, retries, one-time effects, data moves, and compatibility limits. Operations: Add useful signals and logs that hide sensitive data. Set capacity limits and write an operator guide. Test recovery and rollback. Acceptance criteria: Contract and failure-path tests pass. Data and authorization rules still hold during retries and partial failures. Check performance limits, monitoring, recovery, and rollback. Evidence and limits (evidence boundary): The standard covers only the listed scope. It does not choose the visual style, product decision, or Vibulary example. Unknowns to confirm: Where the code runs, data stores, traffic shape, consistency needs, and the security boundary. Also confirm the compatibility period, service goals, and rollback limits.