ADR-0008 · No Data Caching in the Router
Status: Accepted
The router does not cache getData() results. Each call to a route's data hook runs fresh. Components own their own caching, deduplication, and invalidation if they want it.
Why
Caching looks easy until you ask the hard questions: How long? Per user? Per query param? When a mutation in widget A happens, does it invalidate page B? The router has no information to answer any of these — only the component does.
Putting a cache in the router would either be wrong for most consumers or so configurable it becomes its own framework. Better to leave the slot empty and let the component decide. Most components don't need a cache anyway — fetch already has HTTP caching.