fix: 数据库与数据管线 6 个 P1 + 5 个 P2 审查问题修复

P1-1 [context_builder] build_context 共享 session,切片函数传 db 参数,
        回测 20 场并发连接需求从 100+ 降至每场 1 个
P1-2 [bzzoiro] 预加载改为按 raw_events 日期范围 ±30 天按需加载
P1-3 [understat] 批量查询球队 + 比赛,从 1140 次往返降到 3 次
P1-4 [injuries] 批量幂等检查 + 分批 flush,IntegrityError 逐条回退
P1-5 [predict] 删除 threading.Lock,dict 操作原子无需同步锁
P1-6 [models] 添加 (match_id, provider, model) 唯一约束 + 迁移

P2-1 [unit_of_work] get_uow 返回类型改为 AsyncIterator[AsyncSession]
P2-2 [normalize] _parse_date 失败时记录 warning 避免静默丢数据
P2-3 [repositories] find_by_teams_and_date 改用 match_date_date 等值匹配
P2-4 [migration] 幽灵列 cutoff_at 已在 0006 迁移删除(已有)
P2-5 [migration] injuries 约束命名对齐 ORM,UniqueConstraint → 唯一索引

src/db/models.py

@@ -14,6 +14,7 @@ from sqlalchemy import (
     Integer,
     String,
     Text,
+    UniqueConstraint,
     func,
 )
 from sqlalchemy.dialects.postgresql import JSONB
@@ -198,6 +199,11 @@ class Prediction(Base):
     match: Mapped[Match] = relationship(back_populates="predictions")
 
     __table_args__ = (
+        # P1-6: 数据库级唯一约束,防止同一 match+provider+model 产生重复预测
+        UniqueConstraint(
+            "match_id", "provider", "model",
+            name="uq_predictions_match_provider_model",
+        ),
         Index("ix_predictions_match", "match_id"),
         Index("ix_predictions_provider_model", "provider", "model"),
         # 数据截止时间过滤查询用(按 prediction_cutoff_at 取「赛前已生成」的预测)

src/db/repositories.py

@@ -5,7 +5,8 @@ Repository 只负责查询,不负责事务提交。
 """
 from __future__ import annotations
 
-from sqlalchemy import func, select
+from datetime import datetime
+from sqlalchemy import select
 from sqlalchemy.orm import selectinload
 from sqlalchemy.ext.asyncio import AsyncSession
 
@@ -41,9 +42,17 @@ class MatchRepository:
 
         预加载 stats:调用方(understat 回填)会读取 existing.stats,
         async session 下惰性加载会抛 MissingGreenlet。
+
+        P2-3: 使用 match_date_date(已建索引)做等值匹配,避免 func.date()
+        导致的全表扫描。
         """
-        if hasattr(date, "date"):
+        if isinstance(date, datetime):
             date = date.date()
+        elif hasattr(date, "date"):
+            date = date.date()
+        else:
+            # 字符串等其它格式,尝试转换
+            date = datetime.fromisoformat(str(date)).date()
 
         stmt = (
             select(Match)
@@ -51,7 +60,7 @@ class MatchRepository:
             .where(Match.league_id == league_id)
             .where(Match.home_team_id == home_team_id)
             .where(Match.away_team_id == away_team_id)
-            .where(func.date(Match.match_date) == date)
+            .where(Match.match_date_date == date)
         )
         return (await self._session.execute(stmt)).scalar_one_or_none()
 

src/db/unit_of_work.py

@@ -9,12 +9,16 @@ from __future__ import annotations
 
 from collections.abc import AsyncIterator
 from contextlib import asynccontextmanager
+from typing import TYPE_CHECKING
 
 from src.db.base import AsyncSessionLocal
 
+if TYPE_CHECKING:
+    from sqlalchemy.ext.asyncio import AsyncSession
+
 
 @asynccontextmanager
-async def get_uow() -> AsyncIterator[AsyncSessionLocal]:
+async def get_uow() -> AsyncIterator[AsyncSession]:
     """创建新的工作单元(用于非路由上下文)。
 
     用法: