Add a unique constraint for filenames per record

formatscaper/models.py

 import dataclasses
 from typing import List, Optional
 
-from sqlalchemy import ForeignKey, create_engine
+from sqlalchemy import ForeignKey, UniqueConstraint, create_engine
 from sqlalchemy.orm import DeclarativeBase, Mapped, Session, mapped_column, relationship
 
 
@@ -98,6 +98,9 @@ class Result(ModelBase):
     format_id: Mapped[Optional[int]] = mapped_column(ForeignKey("format.id"))
     format: Mapped[Format] = relationship(back_populates="results")
 
+    # filenames are unique per record
+    __table_args__ = UniqueConstraint("record", "filename")
+
     @property
     def risk(self):
         """Calculate the risk assessment for the file."""