Module cache 

Pluggable caching for fetched provider results.

CacheBackend is the trait host apps implement to plug in tier-1 storage (default MemoryBackend is in-process), tier-2 storage (IndexedDbBackend lands in phase 3b), or anything else they like (Redis, file-system, etc.).

CachedEntry carries the DataTable, the wall-clock time it was fetched, the TTL, free-form bulk-invalidation tags, and provider metadata so cache-hits return identical metadata to the original fetch.

Structs

CachedEntry

One cached source entry. Cloning is cheap because DataTable is Arc-backed; metadata + tag clones are a small HashMap/Vec.

MemoryBackend

Default in-process tier-1 cache. Arc<Mutex<HashMap<u64, CachedEntry>>> — no async I/O, no external dependencies, identical behavior on native and WASM.

Enums

CacheError

Cache backend errors. Backed by thiserror so backends can wrap their native error type (Mutex poisoning, IndexedDB errors, IO errors, etc.).

Traits

CacheBackend

Pluggable cache backend trait. ?Send on WASM mirrors the DataSourceProvider / TransformMiddleware story so single-threaded browser environments don’t need Send bounds.