fix(stock): AI 뉴스 호재/악재 명확히 구분

(1) 부호 게이트: top_pos는 score>0, top_neg는 score<0만 분류해 양수(호재)
종목이 악재란에 채워지는 문제 제거. 중립(0)은 양쪽 모두 제외.
(2) 프롬프트: reason을 score 부호와 같은 방향 근거만 쓰도록 명시 —
호재 평가에 악재 내용, 악재 평가에 호재 내용 혼입 금지.
부호 게이트 회귀 테스트 2건 추가.

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

stock/tests/test_ai_news_pipeline.py

@@ -140,6 +140,71 @@ async def test_refresh_daily_no_match_ticker_skipped(conn):
     assert {r["ticker"] for r in rows} == {"005930"}
 
 
+@pytest.mark.asyncio
+async def test_refresh_daily_sign_gate_no_positive_in_neg(conn):
+    """전 종목 양수 점수면 top_neg는 비어야 함 (호재 종목이 악재란에 채워지면 안 됨)."""
+    asof = dt.date(2026, 5, 13)
+    fake_articles_by_ticker = {
+        "005930": [{"title": "h", "summary": "", "press": "", "pub_date": ""}],
+        "000660": [{"title": "h", "summary": "", "press": "", "pub_date": ""}],
+        "373220": [{"title": "h", "summary": "", "press": "", "pub_date": ""}],
+    }
+    fake_stats = {"total_articles": 3, "matched_pairs": 3, "hit_tickers": 3}
+    scores = {"005930": 6.0, "000660": 2.0, "373220": 0.5}  # 모두 양수
+
+    async def fake_score(llm, ticker, news, *, name=None, model="m"):
+        return {
+            "ticker": ticker, "score_raw": scores[ticker], "reason": "r",
+            "news_count": 1, "tokens_input": 1, "tokens_output": 1, "model": model,
+        }
+
+    with patch.object(pipeline, "articles_source") as mas, \
+         patch.object(pipeline, "_analyzer") as ma, \
+         patch.object(pipeline, "_make_llm") as ml:
+        mas.gather_articles_for_tickers = MagicMock(return_value=(fake_articles_by_ticker, fake_stats))
+        ma.score_sentiment = fake_score
+        ml.return_value.__aenter__.return_value = AsyncMock()
+        ml.return_value.__aexit__.return_value = None
+        result = await pipeline.refresh_daily(conn, asof, concurrency=3)
+
+    assert len(result["top_pos"]) == 3
+    assert result["top_neg"] == []  # 양수 종목이 악재란에 들어가면 안 됨
+
+
+@pytest.mark.asyncio
+async def test_refresh_daily_sign_gate_excludes_neutral(conn):
+    """score=0(중립)은 호재·악재 어디에도 포함되지 않음."""
+    asof = dt.date(2026, 5, 13)
+    fake_articles_by_ticker = {
+        "005930": [{"title": "h", "summary": "", "press": "", "pub_date": ""}],
+        "000660": [{"title": "h", "summary": "", "press": "", "pub_date": ""}],
+        "373220": [{"title": "h", "summary": "", "press": "", "pub_date": ""}],
+    }
+    fake_stats = {"total_articles": 3, "matched_pairs": 3, "hit_tickers": 3}
+    scores = {"005930": 3.0, "000660": 0.0, "373220": -3.0}
+
+    async def fake_score(llm, ticker, news, *, name=None, model="m"):
+        return {
+            "ticker": ticker, "score_raw": scores[ticker], "reason": "r",
+            "news_count": 1, "tokens_input": 1, "tokens_output": 1, "model": model,
+        }
+
+    with patch.object(pipeline, "articles_source") as mas, \
+         patch.object(pipeline, "_analyzer") as ma, \
+         patch.object(pipeline, "_make_llm") as ml:
+        mas.gather_articles_for_tickers = MagicMock(return_value=(fake_articles_by_ticker, fake_stats))
+        ma.score_sentiment = fake_score
+        ml.return_value.__aenter__.return_value = AsyncMock()
+        ml.return_value.__aexit__.return_value = None
+        result = await pipeline.refresh_daily(conn, asof, concurrency=3)
+
+    pos_tickers = {r["ticker"] for r in result["top_pos"]}
+    neg_tickers = {r["ticker"] for r in result["top_neg"]}
+    assert pos_tickers == {"005930"}
+    assert neg_tickers == {"373220"}
+    assert "000660" not in pos_tickers and "000660" not in neg_tickers
+
+
 def test_top_market_cap_tickers(conn):
     out = pipeline._top_market_cap_tickers(conn, n=2)
     assert out == ["005930", "000660"]