/cache-strategy

Implement a permanent cache-first strategy: read from cache, fall back to DB on miss, write to cache, invalidate only on data mutation. No expiry timers — the cache stays valid until the underlying data changes.

Philosophy

The goal is one DB read per data item, ever (until it changes):

READ:   cache hit? → return cached value
        cache miss? → query DB → write to cache → return value

WRITE:  update DB → invalidate (or update) cache entry → done

This is the Play Framework model: no TTL, no polling, no background refresh. The cache is always warm and always correct because it is invalidated precisely when the source changes.