Unit of Work (UoW) is the sole owner of the SQLAlchemy Session. Repository classes that receive a Session via constructor injection do not own it — calling rollback() on a shared session rolls back ALL pending work in the transaction, discarding writes from other repos in the same UoW scope.

Removed self.session.rollback() calls from:

  - ProjectRepository.create() (OperationalError/SQLAlchemyDatabaseError handler)

  - ActorRepository.set_default_name() (IntegrityError race-condition handler)

Repositories using the session_factory pattern retain their rollback handlers since

each method creates its own session.

Added BDD regression tests to verify:

  - Repository error handlers never invoke session.rollback()

  - Writes from other UoW repositories are preserved when one operation fails

ISSUES CLOSED: #7489

@@ -0,0 +6,4 @@
+  Background:
+    Given I have a database session with SQLite memory database
+
+  Scenario Outline: ProjectRepository.create does NOT rollback the shared session

@@ -0,0 +42,4 @@
+    And I should be able to retrieve the project by ID
+    And I should be able to retrieve the project by name
+
+  Tags: @tdd_issue, @tdd_issue_7489

@@ -0,0 +32,4 @@
+        "cleveragents.infrastructure.database.models", fromlist=["Base"]
+    )
+    engine = create_engine("sqlite:///:memory:")
+    db_models.Base.metadata.create_all(engine)  # type: ignore

@@ -0,0 +166,4 @@
+        id = 1
+        default_actor_name = None
+
+    preferences_model = FakePreferencesModel()

@@ -0,0 +169,4 @@
+    preferences_model = FakePreferencesModel()
+    actor_prefs_model = __import__(
+        "cleveragents.infrastructure.database.models",
+        fromlist=["ActorPreferencesModel"],

@@ -0,0 +193,4 @@
+    from datetime import UTC, datetime
+
+    if not hasattr(context, "context_repo"):
+        from steps.data_integrity_steps import step_have_database_session  # type: ignore