fix(tests): align stale tests with current API + bypass identity-map cache

- test_recipes: split update test into in-place vs copy-on-write paths
  (PUT now updates in-place when current version has no measurements).
  Added _seed_measurement() helper to force copy-on-write where needed.
- test_tasks::reorder: expunge_all() between POST and GET so the shared
  test session re-fetches RecipeVersion.tasks instead of returning the
  cached collection. Prod uses one session per request, so identity-map
  staleness only affects tests.
- test_measure::save_measurement_proxy: payload aligned to current API
  (version_id is required; pass_fail/deviation are computed server-side).

All 179 tests green.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/backend/tests/test_recipes.py

@@ -1,12 +1,40 @@
 """Tests for recipes router (/api/recipes)."""
 import pytest
 from httpx import AsyncClient
+from sqlalchemy import select
 from sqlalchemy.ext.asyncio import AsyncSession
 
+from src.backend.models.orm.measurement import Measurement
+from src.backend.models.orm.recipe import RecipeVersion
+from src.backend.models.orm.task import RecipeSubtask
 from src.backend.models.orm.user import User
 from src.backend.tests.conftest import auth_headers, create_test_recipe
 
 
+async def _seed_measurement(db: AsyncSession, recipe_id: int, user_id: int) -> None:
+    version_id = (await db.execute(
+        select(RecipeVersion.id).where(
+            RecipeVersion.recipe_id == recipe_id,
+            RecipeVersion.is_current == True,  # noqa: E712
+        )
+    )).scalar_one()
+    subtask_id = (await db.execute(
+        select(RecipeSubtask.id)
+        .join(RecipeSubtask.task)
+        .where(RecipeSubtask.task.has(version_id=version_id))
+    )).scalar_one()
+    db.add(Measurement(
+        subtask_id=subtask_id,
+        version_id=version_id,
+        measured_by=user_id,
+        value=10.0,
+        pass_fail="pass",
+        deviation=0.0,
+        input_method="manual",
+    ))
+    await db.flush()
+
+
 class TestListRecipes:
     """GET /api/recipes tests."""
 
@@ -160,18 +188,13 @@ class TestCreateRecipe:
 class TestUpdateRecipe:
     """PUT /api/recipes/{recipe_id} tests."""
 
-    async def test_update_recipe(
+    async def test_update_recipe_in_place(
         self,
         client: AsyncClient,
         maker_user: User,
         db_session: AsyncSession,
     ):
-        """Updating a recipe creates a new version (copy-on-write).
+        """Updating a recipe without measurements updates current version in-place."""
-
-        We verify the new version exists by listing versions, since
-        SQLAlchemy identity-map staleness with StaticPool can cause
-        ``is_current`` to appear stale in some responses.
-        """
         recipe = await create_test_recipe(db_session, maker_user.id)
         resp = await client.put(
             f"/api/recipes/{recipe.id}",
@@ -183,7 +206,9 @@ class TestUpdateRecipe:
         )
         assert resp.status_code == 200
 
-        # Verify via versions list which always does a clean query
+        # expire identity-map cache so subsequent GETs see fresh data
+        db_session.expunge_all()
+
         versions_resp = await client.get(
             f"/api/recipes/{recipe.id}/versions",
             headers=auth_headers(maker_user),
@@ -191,8 +216,38 @@ class TestUpdateRecipe:
         assert versions_resp.status_code == 200
         versions = versions_resp.json()
         version_numbers = [v["version_number"] for v in versions]
-        assert 1 in version_numbers
+        assert version_numbers == [1]
-        assert 2 in version_numbers
+
+    async def test_update_recipe_copy_on_write(
+        self,
+        client: AsyncClient,
+        maker_user: User,
+        db_session: AsyncSession,
+    ):
+        """Updating a recipe with measurements creates a new version (copy-on-write)."""
+        recipe = await create_test_recipe(db_session, maker_user.id)
+        await _seed_measurement(db_session, recipe.id, maker_user.id)
+        db_session.expunge_all()
+
+        resp = await client.put(
+            f"/api/recipes/{recipe.id}",
+            headers=auth_headers(maker_user),
+            json={
+                "name": "Updated Recipe",
+                "change_notes": "Triggers copy-on-write",
+            },
+        )
+        assert resp.status_code == 200
+        db_session.expunge_all()
+
+        versions_resp = await client.get(
+            f"/api/recipes/{recipe.id}/versions",
+            headers=auth_headers(maker_user),
+        )
+        assert versions_resp.status_code == 200
+        versions = versions_resp.json()
+        version_numbers = sorted(v["version_number"] for v in versions)
+        assert version_numbers == [1, 2]
 
 
 class TestDeleteRecipe:
@@ -222,31 +277,34 @@ class TestRecipeVersioning:
         maker_user: User,
         db_session: AsyncSession,
     ):
-        """Multiple updates create consecutive versions."""
+        """Each update creates a new version when measurements exist (copy-on-write)."""
         recipe = await create_test_recipe(db_session, maker_user.id)
+        await _seed_measurement(db_session, recipe.id, maker_user.id)
+        db_session.expunge_all()
 
-        # Update once -> v2
+        # Update once -> v2 (v1 had measurements)
         await client.put(
             f"/api/recipes/{recipe.id}",
             headers=auth_headers(maker_user),
             json={"change_notes": "Version 2"},
         )
+        db_session.expunge_all()
+        await _seed_measurement(db_session, recipe.id, maker_user.id)
+        db_session.expunge_all()
 
-        # Update again -> v3
+        # Update again -> v3 (v2 now has measurements too)
         await client.put(
             f"/api/recipes/{recipe.id}",
             headers=auth_headers(maker_user),
             json={"change_notes": "Version 3"},
         )
+        db_session.expunge_all()
 
-        # List versions
         resp = await client.get(
             f"/api/recipes/{recipe.id}/versions",
             headers=auth_headers(maker_user),
         )
         assert resp.status_code == 200
         versions = resp.json()
-        version_numbers = [v["version_number"] for v in versions]
+        version_numbers = sorted(v["version_number"] for v in versions)
-        assert 1 in version_numbers
+        assert version_numbers == [1, 2, 3]
-        assert 2 in version_numbers
-        assert 3 in version_numbers

src/backend/tests/test_tasks.py

@@ -189,7 +189,7 @@ class TestReorderTasks:
         """Maker can reorder tasks by providing task IDs in desired order."""
         recipe = await create_test_recipe(db_session, maker_user.id)
 
-        # Add a second task via copy-on-write
+        # Add a second task (no measurements → appended to current version)
         add_resp = await client.post(
             f"/api/recipes/{recipe.id}/tasks",
             headers=auth_headers(maker_user),
@@ -197,7 +197,11 @@ class TestReorderTasks:
         )
         assert add_resp.status_code == 201
 
-        # Get tasks from new version
+        # Force SQLA to re-fetch RecipeVersion.tasks: the shared test session
+        # caches the collection from create_test_recipe, so the GET below would
+        # otherwise return a stale list. In prod each request gets its own session.
+        db_session.expunge_all()
+
         tasks_resp = await client.get(
             f"/api/recipes/{recipe.id}/tasks",
             headers=auth_headers(maker_user),

src/frontend/flask_app/tests/test_measure.py

@@ -61,7 +61,7 @@ class TestSaveMeasurement:
         mock_api_client.post.return_value = {
             "id": 1,
             "subtask_id": 10,
-            "task_id": 5,
+            "version_id": 3,
             "value": 9.95,
             "pass_fail": "pass",
         }
@@ -70,10 +70,8 @@ class TestSaveMeasurement:
             "/measure/save-measurement",
             json={
                 "subtask_id": 10,
-                "task_id": 5,
+                "version_id": 3,
                 "value": 9.95,
-                "pass_fail": "pass",
-                "deviation": 0.05,
             },
             content_type="application/json",
         )
@@ -86,7 +84,7 @@ class TestSaveMeasurement:
         """Missing required fields return 400."""
         resp = logged_in_client.post(
             "/measure/save-measurement",
-            json={"subtask_id": 10},  # missing task_id and value
+            json={"subtask_id": 10},  # missing version_id and value
             content_type="application/json",
         )
         assert resp.status_code == 400