- VectorStore.get_vector() and get_metadata() were hardcoded to access
self.vectors and self.metadata dicts, which are only initialized for
the inmemory backend, causing AttributeError on all persistent backends
(FAISS, Qdrant, Pinecone, Milvus, Weaviate, PgVector, SQLiteVec).
Changes:
- Refactor VectorStore.get_vector() and get_metadata() to branch on
self.backend == 'inmemory' (zero behavior change) and delegate to
self._backend_store otherwise.
- Harden save() to use getattr(self, 'vectors', {}) / getattr(self,
'metadata', {}) to prevent crash when saving a persistent backend store.
- Add get_vector() and get_metadata() to all 7 backend wrappers:
- FAISSStore: get_vector uses index.reconstruct(); get_metadata raises
NotImplementedError (FAISS has no metadata storage natively).
- QdrantStore: uses client.retrieve() with with_vectors/with_payload.
- PineconeStore: wraps existing fetch_vectors() call.
- MilvusStore: raises NotImplementedError (auto_id=True schema discards
string IDs at insert time, making by-ID lookup impossible in this
wrapper's current schema).
- WeaviateStore: uses collection.query.fetch_object_by_id().
- PgVectorStore: wraps existing get_vectors() SQL method.
- SQLiteVecStore: wraps existing get_vectors() SQL method.
- Add TestVectorStoreRetrieval regression tests covering inmemory and
FAISS backends with real (non-mocked) assertions.
All 28 tests pass.