caching-plan.txt
This is slow: <describe the operation and roughly how slow>

Before adding a cache, tell me honestly: is caching the right fix here,
or am I hiding a query I should just make faster?

If caching is right:
- What exactly gets cached, keyed by what.
- How long it lives, and what specifically invalidates it early.
- What a user sees if they get stale data — is that acceptable?

The hard part of caching was never the storing. It is knowing when what you stored stopped being true.