feat(search): Phase 2A E-1 — Qwen 후보 3종 백필 CLI + eval 디스패처 확장 (마이그 328~333)

- 후보 섀도 테이블 6종(전부 vector 타입 — eval=exact scan 이라 인덱스 불요, halfvec 은 C-1 소관)
- workers/phase2a_cand_backfill: resumable(NOT EXISTS)·배치 커밋·동결셋 한정(--doc/chunk-id-max),
  문서/청크 입력 = production 경로 동일 구성 + plain
- CANDIDATE_BACKEND_MAP += cand_qwen06/qwen4/qwen4m (embed_kind=ollama, 쿼리측 instruct prefix
  G-1 핀 문자열, qwen4m = dimensions 1024 MRL)
- qwen4m 적재는 qwen4 에서 SQL 파생(subvector+l2_normalize) — 본 CLI 비대상

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

app/services/search/retrieval_service.py

@@ -63,8 +63,41 @@ CANDIDATE_BACKEND_MAP: dict[str, dict[str, str] | None] = {
         "chunks_table": "document_chunks_cand_snowflake_l_v2",
         "embed_endpoint": "http://embedding-cand-snowflake-l-v2:80/embed",
     },
+    # ─── Phase 2A (embedding-phase2a-1, 2026-06-12): Qwen3-Embedding 후보 3종 ───
+    # embed_kind="ollama" = /api/embed 호출 + 쿼리측 instruct prefix (비대칭 사용,
+    # G-1 fixture 실측: prefix 가 관련쌍 cos +0.016). 문서측은 backfill 이 plain 으로 적재.
+    # qwen4m = 4B 의 MRL 1024d (dimensions 옵션 — Ollama 가 truncate+재정규화 수행, G-1 실측).
+    "cand_qwen06": {
+        "docs_table": "documents_cand_qwen06",
+        "chunks_table": "document_chunks_cand_qwen06",
+        "embed_endpoint": "http://ollama:11434/api/embed",
+        "embed_kind": "ollama",
+        "embed_model": "qwen3-embedding:0.6b",
+    },
+    "cand_qwen4": {
+        "docs_table": "documents_cand_qwen4",
+        "chunks_table": "document_chunks_cand_qwen4",
+        "embed_endpoint": "http://ollama:11434/api/embed",
+        "embed_kind": "ollama",
+        "embed_model": "qwen3-embedding:4b",
+    },
+    "cand_qwen4m": {
+        "docs_table": "documents_cand_qwen4m",
+        "chunks_table": "document_chunks_cand_qwen4m",
+        "embed_endpoint": "http://ollama:11434/api/embed",
+        "embed_kind": "ollama",
+        "embed_model": "qwen3-embedding:4b",
+        "embed_dimensions": 1024,
+    },
 }
 
+# G-1 핀 고정 instruct 문자열 (inventory 2026-06-12-c 기록과 동일해야 함 —
+# 문구 변경 = 저장=조회 불변식 위반과 동급. 쿼리 측 전용, 문서 적재는 plain).
+QWEN3_QUERY_INSTRUCT = (
+    "Instruct: Given a web search query, retrieve relevant passages that answer the query"
+    "\nQuery: "
+)
+
 # 2단계 gate (R2-B1) — SQL string interpolation 직전 final allowlist.
 _VALID_DOCS_TABLE = re.compile(r"^(documents|documents_cand_[a-z0-9_]+)$")
 # corpus_chunks = document_chunks WHERE in_corpus=true 뷰 (Hier-Decomp-1 c2 choke point).
@@ -137,6 +170,34 @@ async def _embed_query_via_tei(endpoint: str, text_: str) -> list[float] | None:
         return None
 
 
+async def _embed_query_via_ollama(cfg: dict, text_: str) -> list[float] | None:
+    """Phase 2A 후보 쿼리 임베딩 — Ollama /api/embed + 비대칭 instruct prefix.
+
+    쿼리 측 전용: QWEN3_QUERY_INSTRUCT 를 선두에 붙인다 (문서 적재 = plain).
+    embed_dimensions 지정(qwen4m) 시 Ollama dimensions 옵션 = MRL truncate+재정규화
+    (G-1 fixture: 1024 출력 L2=1.0 실측). cache 미사용 — slug 별 분포 상이.
+    """
+    if not text_:
+        return None
+    import httpx
+    body: dict = {"model": cfg["embed_model"], "input": [QWEN3_QUERY_INSTRUCT + text_]}
+    if cfg.get("embed_dimensions"):
+        body["dimensions"] = cfg["embed_dimensions"]
+    try:
+        async with httpx.AsyncClient(timeout=60.0) as c:
+            r = await c.post(cfg["embed_endpoint"], json=body)
+            r.raise_for_status()
+            embs = r.json().get("embeddings")
+        if not isinstance(embs, list) or not embs or not isinstance(embs[0], list):
+            raise ValueError("unexpected /api/embed shape")
+        return embs[0]
+    except Exception as exc:
+        logger.warning(
+            "candidate ollama embed failed model=%s err=%r", cfg.get("embed_model"), exc
+        )
+        return None
+
+
 def _query_embed_key(text_: str) -> str:
     return hashlib.sha256(f"{text_}|bge-m3".encode("utf-8")).hexdigest()
 
@@ -323,7 +384,10 @@ async def search_vector(
     else:
         docs_table = cfg["docs_table"]
         chunks_table = cfg["chunks_table"]
-        query_embedding = await _embed_query_via_tei(cfg["embed_endpoint"], query)
+        if cfg.get("embed_kind") == "ollama":
+            query_embedding = await _embed_query_via_ollama(cfg, query)
+        else:
+            query_embedding = await _embed_query_via_tei(cfg["embed_endpoint"], query)
 
     logger.info(
         "[embedding-dispatch] backend=%s docs_table=%s chunks_table=%s snapshot_doc_id_max=%s "

app/workers/phase2a_cand_backfill.py

@@ -0,0 +1,142 @@
+"""Phase 2A 후보 임베딩 백필 CLI (embedding-phase2a-1 E-1).
+
+    docker compose exec -T fastapi python -m workers.phase2a_cand_backfill \
+        --target qwen06 --doc-id-max 41944 --chunk-id-max 104140 [--batch 32]
+
+설계 원칙 (plan r3):
+  - resumable/idempotent: 대상 = NOT EXISTS(후보 테이블) — 중단/재실행 시 이어서.
+    배치 단위 커밋. C-1 백필 게이트 = "후보 카운트 == 동결셋 카운트".
+  - 동결셋: id <= *_id_max AND 베이스라인 embedding IS NOT NULL (AND docs.deleted_at IS NULL).
+    cand 테이블은 동결 범위로만 INSERT (retrieval cand path 가 snapshot filter 를 안 타는 전제).
+  - 문서/청크 입력 = production 경로와 동일 구성(embed_worker._build_embed_input /
+    chunk_worker 의 [제목][섹션][본문]) + plain (instruct prefix 는 쿼리 측 전용 — G-1 불변식).
+  - 임베딩 = Ollama /api/embed 배치 호출 (G-1 fixture: 정규화 출력).
+  - qwen4m 은 본 CLI 대상이 아님 — qwen4 적재 후 SQL 파생(subvector+l2_normalize), plan E-1.
+"""
+
+import argparse
+import asyncio
+import hashlib
+import time
+
+import httpx
+from sqlalchemy import text
+
+from core.database import async_session
+from core.utils import setup_logger
+from models.document import Document
+from workers.embed_worker import _build_embed_input
+
+logger = setup_logger("phase2a_cand_backfill")
+
+OLLAMA_EMBED = "http://ollama:11434/api/embed"
+
+TARGETS = {
+    "qwen06": {
+        "model": "qwen3-embedding:0.6b", "dim": 1024,
+        "docs": "documents_cand_qwen06", "chunks": "document_chunks_cand_qwen06",
+    },
+    "qwen4": {
+        "model": "qwen3-embedding:4b", "dim": 2560,
+        "docs": "documents_cand_qwen4", "chunks": "document_chunks_cand_qwen4",
+    },
+}
+
+
+async def _embed_batch(client: httpx.AsyncClient, model: str, texts: list[str]) -> list[list[float]]:
+    r = await client.post(OLLAMA_EMBED, json={"model": model, "input": texts}, timeout=600)
+    r.raise_for_status()
+    embs = r.json()["embeddings"]
+    if len(embs) != len(texts):
+        raise RuntimeError(f"embed count mismatch: {len(embs)} != {len(texts)}")
+    return embs
+
+
+async def backfill_docs(target: dict, doc_id_max: int, batch: int, http: httpx.AsyncClient) -> int:
+    total = 0
+    while True:
+        async with async_session() as session:
+            rows = (await session.execute(text(f"""
+                SELECT d.id FROM documents d
+                WHERE d.id <= :m AND d.embedding IS NOT NULL AND d.deleted_at IS NULL
+                  AND NOT EXISTS (SELECT 1 FROM {target['docs']} c WHERE c.doc_id = d.id)
+                ORDER BY d.id LIMIT :b
+            """), {"m": doc_id_max, "b": batch})).scalars().all()
+            if not rows:
+                break
+            docs = [(await session.get(Document, i)) for i in rows]
+            inputs = [_build_embed_input(d) for d in docs]
+            embs = await _embed_batch(http, target["model"], inputs)
+            for d, inp, e in zip(docs, inputs, embs):
+                await session.execute(text(f"""
+                    INSERT INTO {target['docs']} (doc_id, embed_input_hash, embedding)
+                    VALUES (:i, :h, cast(:e AS vector))
+                    ON CONFLICT (doc_id) DO NOTHING
+                """), {"i": d.id, "h": hashlib.sha256(inp.encode()).hexdigest()[:16], "e": str(e)})
+            await session.commit()
+            total += len(rows)
+            if total % (batch * 10) < batch:
+                logger.info(f"[{target['docs']}] +{total} (last id={rows[-1]})")
+    return total
+
+
+async def backfill_chunks(target: dict, chunk_id_max: int, batch: int, http: httpx.AsyncClient) -> int:
+    total = 0
+    while True:
+        async with async_session() as session:
+            rows = (await session.execute(text(f"""
+                SELECT c.id, c.doc_id, c.chunk_index, c.section_title, c.text, d.title
+                FROM corpus_chunks c JOIN documents d ON d.id = c.doc_id
+                WHERE c.id <= :m AND c.embedding IS NOT NULL AND d.deleted_at IS NULL
+                  AND NOT EXISTS (SELECT 1 FROM {target['chunks']} k WHERE k.id = c.id)
+                ORDER BY c.id LIMIT :b
+            """), {"m": chunk_id_max, "b": batch})).all()
+            if not rows:
+                break
+            inputs = [
+                f"[제목] {r.title or ''}\n[섹션] {r.section_title or ''}\n[본문] {r.text}"
+                for r in rows
+            ]
+            embs = await _embed_batch(http, target["model"], inputs)
+            for r, e in zip(rows, embs):
+                await session.execute(text(f"""
+                    INSERT INTO {target['chunks']} (id, doc_id, chunk_index, section_title, text, embedding)
+                    VALUES (:i, :d, :x, :s, :t, cast(:e AS vector))
+                    ON CONFLICT (id) DO NOTHING
+                """), {"i": r.id, "d": r.doc_id, "x": r.chunk_index,
+                       "s": r.section_title, "t": r.text, "e": str(e)})
+            await session.commit()
+            total += len(rows)
+            if total % (batch * 10) < batch:
+                logger.info(f"[{target['chunks']}] +{total} (last id={rows[-1]})")
+    return total
+
+
+async def run(target_key: str, doc_id_max: int, chunk_id_max: int, batch: int) -> None:
+    target = TARGETS[target_key]
+    start = time.monotonic()
+    async with httpx.AsyncClient() as http:
+        nd = await backfill_docs(target, doc_id_max, batch, http)
+        nc = await backfill_chunks(target, chunk_id_max, batch, http)
+    mins = (time.monotonic() - start) / 60
+    async with async_session() as session:
+        cd = (await session.execute(text(f"SELECT count(*) FROM {target['docs']}"))).scalar_one()
+        cc = (await session.execute(text(f"SELECT count(*) FROM {target['chunks']}"))).scalar_one()
+    logger.info(
+        f"[{target_key}] 완료 — 이번 run docs +{nd} chunks +{nc} ({mins:.1f}분) · "
+        f"누적 docs {cd} / chunks {cc} (동결 게이트 = 베이스라인 동결셋 카운트와 일치 확인)"
+    )
+
+
+def main() -> None:
+    p = argparse.ArgumentParser(description="Phase 2A 후보 임베딩 백필 (resumable)")
+    p.add_argument("--target", required=True, choices=sorted(TARGETS))
+    p.add_argument("--doc-id-max", type=int, required=True)
+    p.add_argument("--chunk-id-max", type=int, required=True)
+    p.add_argument("--batch", type=int, default=32)
+    a = p.parse_args()
+    asyncio.run(run(a.target, a.doc_id_max, a.chunk_id_max, a.batch))
+
+
+if __name__ == "__main__":
+    main()