Module resident 

Resident access to HNSW indexes that eviction can drop from memory.

Eviction writes an index’s checkpoint to storage and removes it from hnsw_indices. Every insert, search and delete reaches its index through this module, which loads a stored index back before handing it out:

• [lock_resident] locks the index map with the index loaded when storage holds one.
• [lock_resident_or_create] does the same, then creates an empty index only when neither memory nor storage holds one. Creating one over an evicted index would hide every vector it held.

A load awaits storage, so eviction can run between the load and the lock. The eviction mark (VectorState::evicted) catches that: an index absent from memory and still marked is loaded again before the lock is returned.