[CLAUDE] Docs: S31 RAG v1.3 baseline PASS (11/11 recall@5=1.000) + gotcha #52

- eval/runs/: baseline v1.1 final PASS after retrieval.py fix (vector search restored)
- eval/trial-state-lock.json: quality_gate.pass=true, baseline=1.000, avg_rerank=0.847
- docs/gotchas.md: +gotcha #52 qdrant-client 1.18 removed search() silent AttributeError
- docs/STATUS.md: S31 entry — RAG PASS, retrieval.py fix, CLI restart required
- docs/HANDOFF.md: S31 brief + CRITICAL CLI restart note
- docs/changelog/sessions/: S31 session log

Root cause: qdrant-client 1.18 removed search() → vec_results always [] → BM25-only
Fix: retrieval.py query_points().points (applied to AI_INFRA repo)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

docs/changelog/sessions/2026-05-26-1630-s31-rag-baseline-pass.md

@@ -0,0 +1,95 @@
+# Session 31 — RAG v1.3 Baseline PASS + retrieval.py critical fix
+
+**Date:** 2026-05-26
+**Duration:** ~1.5h
+**Commits:** 1 pending (S31 docs/infra)
+**Sub-agents:** 0
+
+## Summary
+
+Session 31 followed directly from S30 (RAG v1.3 setup). S30 had bootstrapped 2949 chunks but the v1.1 baseline was tentative (PENDING_RELOAD). S31 re-ran the eval after CLI restart and discovered the real root cause.
+
+## Root Cause Discovered: qdrant-client 1.18 removed search()
+
+**Symptom:** Most golden set queries returned 0 results even with 2949 Qdrant points green.
+
+**Root cause:** `qdrant-client 1.18.0` removed `QdrantClient.search()` method entirely. `retrieval.py:vector_search()` called `_qdrant.search(...)` which raised `AttributeError`. This exception was silently swallowed by `except Exception: continue` → `vec_results = []` always → pipeline fell back to BM25-only.
+
+**Diagnosis chain:**
+1. q01/q02/q03/q08 worked (BM25 exact match found all tokens in same chunk)
+2. q04/q05/q06/q07/q09/q10/q11 returned 0 (BM25 strict AND failed, vector broken)
+3. Qdrant HTTP `/collections/proj_solution_erp` → `status=green`, `points_count=2949` ✓
+4. BM25 SQLite FTS: `MediatR` → 3 hits, `fallback` → 173 hits, `ApprovalWorkflow` → 40 hits (data IS there)
+5. `python -c "from qdrant_client import QdrantClient; c=QdrantClient(...); c.search"` → AttributeError confirmed
+6. Tested `query_points(query=...).points` → worked, 5 results returned
+
+## Fix Applied
+
+**File:** `D:\Dropbox\CONG_VIEC\AI_INFRA\claude-rag\lib\retrieval.py` — `vector_search()` function
+
+```python
+# Before (broken in qdrant-client 1.18):
+hits = _qdrant.search(
+    collection_name=c,
+    query_vector=query_vector,
+    limit=top_k,
+    with_payload=True,
+)
+for h in hits:
+    results.append({"chunk_id": h.id, ...})
+
+# After (qdrant-client 1.12+ query_points API):
+resp = _qdrant.query_points(
+    collection_name=c,
+    query=query_vector,    # param renamed
+    limit=top_k,
+    with_payload=True,
+)
+for h in resp.points:    # access .points on response
+    results.append({"chunk_id": h.id, ...})
+```
+
+## Eval Results
+
+| Version | recall@5 | hits/11 | Pass |
+|---|---|---|---|
+| v1.0 (S30) | 0.455 | 5/11 | ❌ FAIL |
+| v1.1 tentative (S30 stale MCP) | 0.364 | 4/11 | ❌ FAIL |
+| **v1.1 FINAL (S31 after fix)** | **1.000** | **11/11** | **✅ PASS** |
+
+**avg_top1_rerank:** 0.847 (gate threshold 0.65) ✅
+
+**Negative query behavior (q12/q13/q14):**
+- q12 GraphQL: rerank 0.43 (< 0.7 threshold — not a false positive)
+- q13 Redis: rerank 0.38 — correct exclusion
+- q14 Kubernetes: rerank 0.43 — correct exclusion
+
+## Files Updated
+
+**AI_INFRA:**
+- `claude-rag/lib/retrieval.py` — vector_search() fix
+- `claude-rag/eval_v11.py` — temp eval script (not in SOLUTION_ERP)
+
+**SOLUTION_ERP:**
+- `eval/runs/2026-05-26-baseline-v1.1-final.json` — official baseline record
+- `eval/trial-state-lock.json` — quality_gate.pass=true, baseline_recall=1.000
+- `docs/gotchas.md` — gotcha #52 added
+- `docs/STATUS.md` — S31 entry added
+- `docs/HANDOFF.md` — S31 entry added
+
+## New Gotcha #52
+
+`qdrant-client 1.18` removed `search()` API. When library upgrades break internal API, silent `except Exception: continue` in retrieval pipeline produces no error but returns empty results. Fix: use `query_points().points`. Lesson: pin qdrant-client version OR add health check `hasattr(_qdrant, 'query_points')`.
+
+## Next Session
+
+**CRITICAL:** CLI restart to pick up retrieval.py fix (MCP server still loaded old code in memory).
+
+After CLI restart:
+- Live `search_memory` will use fixed vector + BM25 pipeline
+- RAG recall@5 = 1.000 confirmed
+
+**Other pending:**
+- Curate 4 sub-agent MEMORY files (Implementer over threshold)
+- Plan B-Wrap (Contract V2 test bundle BW1-BW7)
+- Phase 9 UAT hard blockers (SMTP, rotate creds, SQL backup, win-acme cert)