Resolves two gaps found in a project-state review:
1. Python build was broken: PyO3/numpy 0.23 caps at Python 3.13 but the
environment has 3.14. Bumped to 0.28 and updated the two breaking APIs
(PyObject -> Py<PyAny>, allow_threads -> detach). The extension module now
imports and round-trips under Python 3.14, unblocking cargo build --workspace.
2. The "HNSW vector search over agent memories" headline was unwired:
clawhdf5-ann had zero dependents and the agent used a linear cosine+BM25 scan.
- clawhdf5-ann is now a live index: insert, mark_deleted (soft delete with a
deleted bitset, traversed but never returned), compact, and a format
version tag (v2) with backward-compatible load of v1 files.
- clawhdf5-agent wires HNSW behind the `hnsw` feature (ON by default). The
index mirrors the cache (node id == cache index) and self-heals: it rebuilds
whenever hnsw_synced_len drifts from cache.len(), so unhooked pushes can't
desync it. Non-indexable stores (no/zero-dim/mixed embeddings) and queries
whose dim doesn't match fall back to the exact linear scan.
- hybrid.rs gains merge_vector_keyword, shared by the linear and HNSW paths.
- tests/hnsw_integration.rs validates recall vs a brute-force oracle plus
insert/delete/batch behaviour.
Disable HNSW for exact search with `--no-default-features --features float16`.
Co-Authored-By: Claude Opus 4.8 (1M context) <[email protected]>
