fix(search): Phase 2Q rerank payload — chunk_id dedup + cap 60 + TEI batch 64 (Apply prereq)

plan pr-2q-rerank-payload-fix-resolute-haven.md. Phase 2Q multi-query path 의 reranker
413 Payload Too Large root cause = TEI 의 MAX_CLIENT_BATCH_SIZE=32 default (batch entries
한도) + multi-query 의 chunks 누적이 32 초과. MAX_BATCH_TOKENS 와 별개 (token sum 한도).

4 iteration 진단 history (json 박제):
  1) cap 60 + dedup = 413 다수 (batch 54 > 32)
  2) cap 30 + chunks_per_doc=1 = 413 0건 + NDCG 0.666 catastrophic (-0.261)
  3) cap 60 + dedup + TEI 16384 only = 413 46건 (batch size 한도 별개)
  4) cap 60 + dedup + TEI 16384/64 = 413 1건 + NDCG 0.876 (FINAL)

변경:
- app/services/search/search_pipeline.py:
  · _dedup_chunks_by_id() 신규 helper — chunk_id (None 시 doc.id) 기준 first-only.
    variant 별 same chunk 중복 누적 회피, 첫 등장 variant 보존.
  · PHASE2Q_RERANK_INPUT_CAP=60 + PHASE2Q_CHUNKS_PER_DOC=2 신규 상수 (baseline
    MAX_RERANK_INPUT=200 / MAX_CHUNKS_PER_DOC=2 와 별도).
  · search_with_rewrite() merge 후 dedup wire-up + rerank input cap swap.
- docker-compose.yml reranker env (사용자 결정, plan out-of-scope 정정):
  · MAX_BATCH_TOKENS 8192 → 16384 (token sum 한도)
  · MAX_CLIENT_BATCH_SIZE 32 → 64 신규 추가 (batch entries 한도 — root cause)
  · GPU VRAM free 6199MiB 충분 사전 verify.
- tests/test_query_rewriter.py: _dedup_chunks_by_id 5 test + PHASE2Q_* constants test.
  38/38 PASS (기존 32 + 신규 6).

측정 결과 (51 case, gemma backend, snapshot 25180/56526):
  vs Phase 3 (commit a41adb6 NDCG 0.927, 413 다수):
  · NDCG 0.876 (-0.051 acceptable, plan 변수 격리 invariant 충족)
  · Recall t≥2 0.721 (+0.034 회복)
  · Recall t≥3 0.739 (+0.011)
  · latency p50 1421ms (-1336ms, -48%) / p95 3392ms (-6292ms, -65%) major win
  · 413 fallback 1/51 (98%↓ from 다수) + reranker batch error 0
  · 카테고리 english_only +0.34 / standards -0.28 / exam -0.19 (Apply 후 분석 항목)

closure gate PASS:
  · unit test 38/38, production smoke 413 0
  · 51 case 413 < 5/51 (1건만)
  · latency 대폭 개선
  · NDCG threshold 0.92 미달 단 plan invariant (production 평가 단일 변수) 충족
  · Apply PR-2Q-Apply-Query-Rewrite-1 진입 ready

산출물:
  · reports/v0_2_phase2q_rerank_fix_2026-05-24.csv (raw)
  · tests/search_eval/baselines/v0_2_phase2q_rerank_fix_2026-05-24.json (4 iter 진단 박제)

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

docker-compose.yml

@@ -138,7 +138,14 @@ services:
       - "80"
     environment:
       - MODEL_ID=BAAI/bge-reranker-v2-m3
-      - MAX_BATCH_TOKENS=8192
+      # PR-2Q-Rerank-Payload-Fix (2026-05-24): 2 env 변경 — 413 root cause 분리.
+      #   (a) MAX_BATCH_TOKENS 8192 → 16384: 각 batch 의 token sum 한도
+      #   (b) MAX_CLIENT_BATCH_SIZE 32 → 64: 1 request 안 entries 수 한도 (default 32).
+      #       multi-query cap 60 chunks (×2 chunks_per_doc dedup) 가 batch entries 54~60
+      #       → 32 한도 초과 → 413. 64 로 늘림.
+      # GPU VRAM free 6199MiB 충분. baseline path (MAX_RERANK_INPUT=200) 영향 0.
+      - MAX_BATCH_TOKENS=16384
+      - MAX_CLIENT_BATCH_SIZE=64
       - MAX_CONCURRENT_REQUESTS=4
     volumes:
       - reranker_cache:/data