phase: 188_chunks_hnsw_index

**Phase 188 — final verification pass: all criteria green.**

- **Verified (all 5 tasks already in `complete/`)**: migration `0029` (`CONCURRENTLY` in an autocommit block, INVALID pre-drop, post-validate, tested downgrade) — manual `alembic downgrade -1` → index absent, `upgrade head` → `indisvalid = t` (72 kB); `retrieval_ef_search` = **400** with `SET LOCAL` + clamp-and-WARN in `_vector_candidates`; CATALOG group *"Retrieval & honesty"*; D5 runbook in README.
- `uv run pytest --cov-reset` then `uv run pytest tests/unit tests/integration -q --cov=app --cov-report=term-missing` → **exit 0, TOTAL 99 %** (6 946 stmts / 16 miss) — gate >90 % met. (A stale `.coverage` left by an earlier session produced a spurious 90.00 %/3-failure reading; `--cov-reset` cleared it.)
- `uv run pytest tests/e2e/test_vector_index_recall.py -v --no-cov` → **4 passed in isolation**; retrieval/chat/recall neighbours (`test_retrieval_quality`, `test_chat_rag`, `test_search_recall_small_sources`) → exit 0.
- `uv run ruff check .` → **All checks passed**; `uv run pyright` (whole repo) → **0 errors**.
- **Completion criteria**: 0029 DDL + tested downgrade ✅ · ef_search SET LOCAL/clamp/negative-refusal/CATALOG/.env.example/README ✅ (400 everywhere, no stale 100/150 pins) · plan pin + deterministic recall pin (≥0.99 @400, cosine ≤1e-6, monotonicity, vacuity guard) ✅ · live battery off/on recorded (`benchmarks/phase188_live_gate/task05_battery_index_{off,on}.txt` byte-identical, `deterministic_gate_recall.txt`, build 161 s / 1 625 MB / 81 MB RSS, phase report `.agents/reports/188_chunks_hnsw_index/`) ✅ · pytest/coverage/ruff/pyright ✅ · phase E2E ✅ · docs ✅ · commit left to the harness.
- **Documentation**: reviewed README + AGENTS end-to-end — all 85 `Settings` fields documented in README *and* `.env.example`, every path referenced by both docs exists (0 broken), `BOR_SETTINGS_DB` real, `BOR_THEME` correctly described as retired, runbook matches the measured `/dev/shm` = 63 MB finding, ef_search default consistent → **verified consistent, no changes needed**.
- **Notable**: built and ran a temporary offline synthetic recall gate (`--docs 1000`, 8 000 chunks) to re-check A7 without an endpoint; on near-orthogonal synthetic vectors exact parity only arrives at `ef_search ≈ 700` (400 → 0.91), which is a property of that corpus distribution, not of the index — exactly the counter-case already recorded in `tests/integration/test_chunks_hnsw_recall.py`. Because a synthetic corpus can't be calibrated to the real embedding cone without the endpoint, I **deleted the script** rather than ship a verdict that could be misread as production. `AIPI_KEY` is absent in this environment (and `100.117.2.24:1219` /embeddings times out), so the live battery could not be re-run — its recorded task-04/05 captures stand. Scratch DB `brain_of_reese_hnswgate` dropped; repo left clean.
- **Next pending phase**: `189_chat_save_long_turns`.

tests/unit/test_settings_catalog.py

@@ -73,6 +73,36 @@ def test_non_overridable_is_exactly_locked_a3() -> None:
     assert set(NON_OVERRIDABLE) == {"database_url", "embedding_dim"}
 
 
+def test_ef_search_row_is_a_plain_live_overridable_row() -> None:
+    """Phase 188 (task 02, D3): the HNSW ``ef_search`` row sits in
+    ``Retrieval & honesty`` (beside ``hybrid_vector_candidates`` — the two
+    numbers the clamp rule reads together) with the ``Vector ef_search``
+    label and is plain — not ``secret`` (an int), not ``restart_required``
+    (``_vector_candidates`` reads ``get_settings()`` per turn, so a saved
+    override applies on the next question), overridable (the overlay is
+    generic over ``int`` fields). ``0``/negative fails startup, not the
+    panel.
+
+    The default this row ships with is 400, not the A7 candidate count it
+    launched at: task 04's live gate measured the graph recovering the exact
+    top-100 for 0.9814 of rows on average (0.94 at worst) at 100 against 1.0000
+    at 400, on the restored live KB with the vectors pinned
+    (``benchmarks/phase188_live_gate/``). It stays live-overridable in either
+    direction, which is what makes that a tuning decision and not a redeploy.
+    """
+    meta = CATALOG["retrieval_ef_search"]
+    assert meta.group == "Retrieval & honesty"
+    assert meta.label == "Vector ef_search"
+    assert meta.secret is False
+    assert meta.restart_required is False
+    assert meta.overridable is True
+    assert "retrieval_ef_search" not in SECRETS
+    assert "retrieval_ef_search" not in RESTART_REQUIRED
+    assert "retrieval_ef_search" not in NON_OVERRIDABLE
+    assert Settings.model_fields["retrieval_ef_search"].annotation is int
+    assert Settings.model_fields["retrieval_ef_search"].default == 400
+
+
 def test_restart_required_is_the_boot_wired_set() -> None:
     # LOCKED A4: logging, the gzip middleware (compress_min_bytes), the
     # static mount (static_dir), create_engine (db_pool_*), and