Cache a public API response in an AI app: freshness, variants and invalidation

A worked example: where the task becomes difficult

A fictional resource directory serves the same public categories to every visitor, making it a suitable cache candidate. A neighboring endpoint returns account preferences under a similar URL. Applying one broad caching rule to both would leak or mix private results. Classify responses before optimizing and keep user-specific behavior outside the shared public cache.

Decisions to make before implementation

Identify which query parameters change the result and include them in the relevant key. Define how long stale information is acceptable and whether a background refresh is suitable. Choose application, server or delivery-layer caching based on deployment behavior. Treat errors and empty results deliberately: a temporary failure should not become an apparently valid long-lived summary.

A practical sequence for the work

Use the sequence below as a task boundary, not as a claim that the example has been executed. Work with approved inputs and the project’s actual architecture. If a required integration or permission is unavailable, keep that stage visibly incomplete rather than generating a plausible substitute result.

• Classify response visibility and the acceptable freshness window.
• Define key variants and the layer that owns the cache.
• Implement bounded reuse and a deliberate refresh or invalidation path.
• Test changed data, parameter variants and private-response exclusion.

A detailed brief you can adapt for your agent

Replace the illustrative context with your approved facts and controlled inputs. Keep the stated boundaries when adapting the brief. The expected deliverable matters more than a particular tool name: ask for an explanation grounded in the inspected material and evidence for the requested outcome.

Cache the public category endpoint under this freshness policy. Inspect response visibility and parameter variants first. Define the key, lifetime and refresh behavior at the intended deployment layer. Keep account preferences out of the shared cache and handle errors separately. Test source updates and different interval requests.

Failure modes that an attractive preview can hide

A cache can improve response time while serving the wrong interval, language or account. Keep keys tied to the result contract. Long-lived caching of an error can make recovery look broken. Do not infer current state from an old cached payload without showing its timestamp where the user’s decision depends on freshness.

Technical references: MDN: HTTP caching

Acceptance checks and the evidence to retain

Keep the cache classification, key contract, freshness policy and observed hit/miss behavior. Document what can remain stale and for how long.

Specific answers

Common questions