Optimize signal read paths and enforce score invariants

app/database.py

@@ -1,5 +1,8 @@
 from collections.abc import AsyncGenerator
+from typing import Any
 
+from sqlalchemy.dialects.postgresql import insert as postgresql_insert
+from sqlalchemy.dialects.sqlite import insert as sqlite_insert
 from sqlalchemy.ext.asyncio import (
     AsyncSession,
     async_sessionmaker,
@@ -28,6 +31,13 @@ class Base(DeclarativeBase):
     pass
 
 
+def insert_for_session(session: AsyncSession, table: Any) -> Any:
+    """Build a dialect-native INSERT that supports conflict handling."""
+    if session.get_bind().dialect.name == "postgresql":
+        return postgresql_insert(table)
+    return sqlite_insert(table)
+
+
 async def get_session() -> AsyncGenerator[AsyncSession, None]:
     async with async_session_factory() as session:
         yield session