Create the runnable skeleton and contracts

Implement types or schemas around secrets manager path openai/prod so illegal states are unrepresentable at the boundary. For answer API + indexer sharing provider key via versioned secrets manager, trusted inputs come from sessions, signatures, pinned digests, or workload identity — not from free-form model text. security engineer rotating openai/prod after contractor offboarding should be able to read the contract and know which fields are optional, which are enumerated, and which abort the request. Constructors and boot paths must not perform provider side effects; injection points keep tests honest.

Document required env vars in .env.example with placeholders only. Rotation story belongs later, but the contract already forbids printing secrets and forbids defaulting to fail-open when a dependency is missing. Invariant to encode in types/tests: dual-key window: readers accept v1+v2; revoke v1 only after emit proves zero v1 use for 30m. If a config number lacks units, fix the name (timeout_ms, rpm_hard) before writing logic.

Create fixtures for the golden path and for SEC-REVOKE-EARLY-21. Name files after the behavior (429-retry-after.json, cross-tenant.json, empty-citation.json) rather than test1. Each fixture carries expected status/code. This kit is the shared language for validation and failure pages.

Compatibility promise: additive fields may appear only if readers ignore unknowns safely; breaking changes bump a version visible on the wire. For AI payloads, size limits arrive before JSON parse when hostile blobs are a risk. Document how clock skew, idempotency keys, and tracing headers travel through answer API + indexer sharing provider key via versioned secrets manager. If you use feature flags later, the contract already states that flags are not authorization. Link each config knob to a unit and a failure mode (“0 means disabled” vs “0 means divide-by-zero”). A peer reviewing the PR should find SEC-REVOKE-EARLY-21 named in a comment on the adversarial fixture.

Generate OpenAPI or a typed client only after the hand schema is stable for one fixture round-trip. Record how errors look on the wire — problem+json, envelope, or bare status — and stick to one. Clock sources must be injectable for skew tests. If webhooks appear later, document signature header names now even as TODOs. Keep sample payloads UTF-8 and free of real emails. Add a makefile or npm script that validates schemas without network. In this chapter the product is answer API + indexer sharing provider key via versioned secrets manager, the human stakeholder is security engineer rotating openai/prod after contractor offboarding, and the incident id you design against is SEC-REVOKE-EARLY-21. Re-state the oracle in your notes — rotate to v2 → deploy → traffic on v2 → revoke v1 with audit event ROT-2026-07-30 — and keep the invariant visible: dual-key window: readers accept v1+v2; revoke v1 only after emit proves zero v1 use for 30m. Track secret_version_share and auth_fail_rate as the scoreboard. Surface under change control: secrets manager path openai/prod. If you only have forty minutes, finish the fixture for revoke v1 while indexer still cached v1 → 401 storm before polishing UI. Promotion language stays ternary: promote, hold, or roll back based on evidence, not hope.