CacheStore

Storage and nearest-neighbour search behind a SemanticCache.

kmemo splits responsibilities on purpose: the store owns where entries live and when they are dropped (capacity, eviction, TTL), while SemanticCache owns whether a candidate is good enough to serve (threshold, guards, verification). That split is what lets a Redis or pgvector adapter delegate expiry to the database without reimplementing any match logic.

Implementations must honour three rules:

1. search never returns an expired entry. Expiry is the store's business; the cache trusts it.

2. search returns at most limit results, sorted by descending similarity.

3. Every method is safe to call concurrently from multiple coroutines.

Inheritors