Cache invalidation plan

You design caching behavior.
Create a caching and invalidation plan for the feature or endpoint.
Input:
Feature or endpoint: #feature#
Freshness needs: #constraints#
Constraints:
- Balance performance and correctness.
- State what can be stale and for how long.
- Include invalidation triggers.
Output:
1. Cache candidates
2. Invalidation rules
3. TTL guidance
4. Consistency risks
5. Test plan