Initial public ModelForge release

backend/src/modelforge_api/db.py

@@ -0,0 +1,38 @@
+from collections.abc import Generator
+from typing import Any, cast
+
+from sqlalchemy import CursorResult, Engine, create_engine
+from sqlalchemy.engine import Result
+from sqlalchemy.orm import Session
+
+from modelforge_api.persistence.runtime_engine import register_application_engine
+from modelforge_api.settings import get_settings
+
+
+def rows_affected(result: Result[Any]) -> int:
+    """How many rows a DML statement actually changed.
+
+    `Session.execute` is typed as returning `Result`, which carries no `rowcount`; a DML statement
+    always returns a `CursorResult`, which does. SQLAlchemy 2.0.52 narrowed that return type, so
+    reading `.rowcount` directly stopped type-checking — while continuing to work at runtime.
+
+    The cast is where that knowledge lives, once, rather than at ten call sites. It matters more
+    than it looks: every single-use claim in the platform is a conditional UPDATE whose row count
+    decides the winner, and that is what makes enrolment tokens and lifecycle claims atomic instead
+    of merely usually-correct.
+    """
+
+    return cast("CursorResult[Any]", result).rowcount
+
+
+def build_engine(database_url: str | None = None) -> Engine:
+    url = database_url or get_settings().database_url
+    return register_application_engine(create_engine(url, pool_pre_ping=True))
+
+
+engine = build_engine()
+
+
+def get_session() -> Generator[Session, None, None]:
+    with Session(engine) as session:
+        yield session