Function read_test_db 

pub fn read_test_db(store_dir: StoreDir, namespace: &str) -> Database

The synthetic store’s schema and Database constructors, which the database layer owns and its own tests open directly. Open a read-test Database whose note_photos child carries a blob in namespace, so read_blob’s locality dispatch can resolve a blob in that namespace up to its gated notes root. The decl’s namespace MUST match the blobs the test reads (the read path resolves the carrying table from the blob’s namespace); its provenance/fill don’t matter to that resolution (the read reads the row → root → gate, and takes provenance off the BlobRef), so this fixes them. Pair with Database::plant_blob_row_for_test.