Cache

Outcome: Design or review Cache for this system while keeping data correct, secure, and easy to operate. User context: A product catalog stays in the cache for five minutes. An inventory update clears that copy at once. Technical concept or control: Cache. Why it fits: Use a cache only when the age limit, owner, keys, and invalidation rules are clear. Do not use it when: Never cache sensitive, user-only, or fast-changing data under shared keys. 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): No single official standard controls the whole term. Its meaning may change across teams, platforms, or frameworks. 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.