coalesce safe identifier task duplicates

Assistant: codex
Assistant-Model: gpt-5.6-sol
Assistant-Session: 01a053ff-1d6f-7fe2-ac1c-a6eb40a42a0c

tests/test_work_record_identifier_migration.py

@@ -318,6 +318,111 @@ async def test_repository_migration_accepts_mixed_legacy_and_derived_projection(
     assert retried.already_derived == 2
 
 
+@pytest.mark.asyncio
+async def test_repository_migration_coalesces_identical_unreferenced_task_duplicate(
+    test_engine,
+):
+    factory = async_sessionmaker(test_engine, class_=AsyncSession, expire_on_commit=False)
+    ids = await _seed_projection(factory, "duplicate-repo")
+    plan = _sealed_plan("duplicate-repo", ids["workplan"], ids["task"])
+    task_new = _derived("TEST-WP-0001-T01")
+    workplan_new = _derived("TEST-WP-0001")
+
+    async with factory() as session:
+        await session.execute(
+            text("DELETE FROM workplan_dependencies WHERE to_task_id = :task_id"),
+            {"task_id": ids["task"]},
+        )
+        await session.execute(
+            text("DELETE FROM progress_events WHERE task_id = :task_id"),
+            {"task_id": ids["task"]},
+        )
+        await session.execute(
+            text("DELETE FROM token_events WHERE task_id = :task_id"),
+            {"task_id": ids["task"]},
+        )
+        await session.execute(
+            text("DELETE FROM tasks WHERE parent_task_id = :task_id"),
+            {"task_id": ids["task"]},
+        )
+        legacy = await session.get(Task, ids["task"])
+        session.add(
+            Task(
+                id=task_new,
+                workplan_id=legacy.workplan_id,
+                record_id="TEST-WP-0001-T01",
+                title=legacy.title,
+                description=legacy.description,
+                status=legacy.status,
+                priority=legacy.priority,
+                assignee=legacy.assignee,
+                due_date=legacy.due_date,
+                blocking_reason=legacy.blocking_reason,
+                needs_human=legacy.needs_human,
+                intervention_note=legacy.intervention_note,
+                parent_task_id=legacy.parent_task_id,
+            )
+        )
+        await session.commit()
+
+    async with factory() as session:
+        result = await apply_repository_identifier_migration(
+            session, plan, "duplicate-repo"
+        )
+    assert result.migrated == 2
+    assert result.already_derived == 0
+
+    async with factory() as session:
+        assert await session.get(Task, ids["task"]) is None
+        task = await session.get(Task, task_new)
+        assert task is not None
+        assert task.workplan_id == workplan_new
+        assert task.record_id == "TEST-WP-0001-T01"
+
+    async with factory() as session:
+        await reverse_repository_identifier_migration(session, plan, "duplicate-repo")
+    async with factory() as session:
+        task = await session.get(Task, ids["task"])
+        assert task is not None
+        assert task.record_id == "TEST-WP-0001-T01"
+        assert await session.get(Task, task_new) is None
+
+
+@pytest.mark.asyncio
+async def test_repository_migration_rejects_referenced_task_duplicate(test_engine):
+    factory = async_sessionmaker(test_engine, class_=AsyncSession, expire_on_commit=False)
+    ids = await _seed_projection(factory, "referenced-duplicate-repo")
+    plan = _sealed_plan(
+        "referenced-duplicate-repo", ids["workplan"], ids["task"]
+    )
+    async with factory() as session:
+        legacy = await session.get(Task, ids["task"])
+        session.add(
+            Task(
+                id=_derived("TEST-WP-0001-T01"),
+                workplan_id=legacy.workplan_id,
+                record_id="TEST-WP-0001-T01",
+                title=legacy.title,
+                description=legacy.description,
+                status=legacy.status,
+                priority=legacy.priority,
+                assignee=legacy.assignee,
+                due_date=legacy.due_date,
+                blocking_reason=legacy.blocking_reason,
+                needs_human=legacy.needs_human,
+                intervention_note=legacy.intervention_note,
+                parent_task_id=legacy.parent_task_id,
+            )
+        )
+        await session.commit()
+
+    async with factory() as session:
+        with pytest.raises(IdentifierMigrationError, match="inbound references"):
+            await apply_repository_identifier_migration(
+                session, plan, "referenced-duplicate-repo"
+            )
+
+
 @pytest.mark.asyncio
 async def test_repository_migration_rejects_neither_legacy_nor_derived(test_engine):
     factory = async_sessionmaker(test_engine, class_=AsyncSession, expire_on_commit=False)