Optimize signal read paths and enforce score invariants

app/models/fundamental.py

@@ -1,6 +1,6 @@
 from datetime import date, datetime
 
-from sqlalchemy import Date, DateTime, Float, ForeignKey, Text
+from sqlalchemy import Date, DateTime, Float, ForeignKey, Text, UniqueConstraint
 from sqlalchemy.orm import Mapped, mapped_column, relationship
 
 from app.database import Base
@@ -8,6 +8,9 @@ from app.database import Base
 
 class FundamentalData(Base):
     __tablename__ = "fundamental_data"
+    __table_args__ = (
+        UniqueConstraint("ticker_id", name="uq_fundamental_data_ticker"),
+    )
 
     id: Mapped[int] = mapped_column(primary_key=True)
     ticker_id: Mapped[int] = mapped_column(