test(tasks): copre recipe_id nel copy-on-write di create_task (#4)

Sospetto MissingGreenlet su TaskResponse.recipe_id (via RecipeTask.version)
quando create_task passa per il copy-on-write - il task appena creato non
ha .version precaricato. Test aggiunto: verde, non riproducibile. La
lazy load risolve via identity map (new_version è già nella sessione,
FK semplice → use_get), senza toccare il DB. Test tenuto come guardia
di regressione.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

src/backend/tests/test_tasks.py

@@ -73,6 +73,45 @@ class TestCreateTask:
         assert len(data["subtasks"]) == 1
         assert data["subtasks"][0]["description"] == "Surface roughness"
 
+    async def test_create_task_on_version_with_measurements_has_recipe_id(
+        self,
+        client: AsyncClient,
+        maker_user: User,
+        measurement_tec_user: User,
+        db_session: AsyncSession,
+    ):
+        """Copy-on-write branch (gitea#4): TaskResponse.recipe_id must not crash."""
+        recipe = await create_test_recipe(db_session, maker_user.id, code="COW-CT")
+        task = (await client.get(
+            f"/api/recipes/{recipe.id}/tasks", headers=auth_headers(maker_user),
+        )).json()[0]
+        subtask_id = task["subtasks"][0]["id"]
+        assert (await _measure(
+            client, measurement_tec_user, subtask_id, task["version_id"]
+        )).status_code == 200
+
+        resp = await client.post(
+            f"/api/recipes/{recipe.id}/tasks",
+            headers=auth_headers(maker_user),
+            json={
+                "title": "New Task After Measurement",
+                "subtasks": [
+                    {
+                        "marker_number": 1,
+                        "description": "Surface roughness",
+                        "nominal": 5.0,
+                        "utl": 5.5,
+                        "ltl": 4.5,
+                        "unit": "um",
+                    }
+                ],
+            },
+        )
+        assert resp.status_code == 201, resp.text
+        data = resp.json()
+        assert data["recipe_id"] == recipe.id
+        assert data["version_id"] != task["version_id"]
+
 
 class TestUpdateTask:
     """PUT /api/tasks/{task_id} tests."""