refactor(tests): one definition each for the copied fixtures and fakes (#2825, milestone 296 area 1)

The shape ledger showed the same test scaffolding defined over and over:
_bind_user x12 (byte-identical), _dispose_engine x10 in three wordings,
_no_supersession x3, _make_mock_session x7 in three subsets, a get-or-create
User helper x2 (+3 inlined), and fifteen hand-rolled MagicMock note factories
each re-explaining the same "an auto-MagicMock attribute is truthy" hazard
(note 2109).

Now: conftest.py carries _bind_user / _dispose_engine / _no_supersession as
opt-in fixtures (pytestmark = usefixtures(...) per module, so unit tests pay
nothing), and tests/helpers.py carries make_mock_session(), ensure_user() and
fake_note(**attrs) — the hazard documented once, real values on every
attribute the product reads. Call sites were rewritten by AST so titles with
dashes and commas survived; the three SimpleNamespace _note stand-ins that
only feed a single function stay local.

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

tests/test_mcp_tool_notes.py

@@ -1,20 +1,16 @@
 """Tests for fable_*_note tools."""
-from unittest.mock import AsyncMock, MagicMock, patch
+from unittest.mock import AsyncMock, patch
 
 import pytest
 
-from scribe.mcp._context import _user_id_ctx
 from scribe.mcp.tools.notes import (
     list_notes, get_note, create_note,
     update_note, delete_note,
 )
+from tests.helpers import fake_note
 
 
-@pytest.fixture(autouse=True)
-def _bind_user():
-    token = _user_id_ctx.set(7)
-    yield
-    _user_id_ctx.reset(token)
+pytestmark = pytest.mark.usefixtures("_bind_user")
 
 
 @pytest.fixture(autouse=True)
@@ -32,21 +28,6 @@ def _no_supersession():
         yield
 
 
-def _fake_note(*, user_id: int = 7, **overrides) -> MagicMock:
-    note = MagicMock()
-    base = {"id": 1, "title": "t", "body": "b", "tags": [], "is_task": False}
-    base.update(overrides)
-    note.to_dict.return_value = base
-    # Real values, not auto-attributes: get_note reads deleted_at, and compares
-    # user_id against the bound caller to decide whether to attach a shared/owner
-    # marker. A MagicMock is truthy on both, so it would read as another user's
-    # trashed note and reach for the DB (note 2109).
-    note.id = base["id"]
-    note.user_id = user_id
-    note.deleted_at = None
-    return note
-
-
 @pytest.mark.asyncio
 async def test_create_note_blocked_by_duplicate_gate():
     from scribe.services.dedup import DuplicateMatch
@@ -67,7 +48,7 @@ async def test_create_note_force_bypasses_duplicate_gate():
     find_mock = AsyncMock()
     with patch("scribe.mcp.tools.notes.dedup_svc.find_duplicate_note", find_mock), \
          patch("scribe.mcp.tools.notes.notes_svc.create_note",
-               AsyncMock(return_value=_fake_note(id=3))):
+               AsyncMock(return_value=fake_note(id=3))):
         out = await create_note(title="dup", force=True)
     assert out["id"] == 3
     find_mock.assert_not_called()
@@ -75,7 +56,7 @@ async def test_create_note_force_bypasses_duplicate_gate():
 
 @pytest.mark.asyncio
 async def test_list_notes_repackages_tuple_into_dict():
-    rows = [_fake_note(id=1), _fake_note(id=2)]
+    rows = [fake_note(id=1), fake_note(id=2)]
     with patch(
         "scribe.mcp.tools.notes.notes_svc.list_notes",
         AsyncMock(return_value=(rows, 2)),
@@ -128,7 +109,7 @@ async def test_list_notes_limit_clamped():
 
 @pytest.mark.asyncio
 async def test_get_note_returns_dict():
-    fake = _fake_note(id=5, title="found")
+    fake = fake_note(id=5, title="found")
     with patch(
         "scribe.mcp.tools.notes.notes_svc.get_note_for_user",
         AsyncMock(return_value=(fake, "owner")),
@@ -153,7 +134,7 @@ async def test_get_note_warns_in_words_when_a_later_note_overtook_it():
     field to notice would be worse than not surfacing it, because the reader
     acts on it confidently either way.
     """
-    fake = _fake_note(id=5, title="June's answer")
+    fake = fake_note(id=5, title="June's answer")
     with patch("scribe.mcp.tools.notes.notes_svc.get_note_for_user",
                AsyncMock(return_value=(fake, "owner"))), \
          patch("scribe.mcp.tools.notes.supersession_svc.get_relations",
@@ -170,7 +151,7 @@ async def test_get_note_opens_a_shared_record_and_says_whose_it_is():
     that menu can list a collaborator's note reached through a shared project.
     An owner-only fetch would answer "not found" for a record the agent was just
     handed — and the web UI opens the same note fine."""
-    theirs = _fake_note(id=5, title="Their note", user_id=9)
+    theirs = fake_note(id=5, title="Their note", user_id=9)
     with patch(
         "scribe.mcp.tools.notes.notes_svc.get_note_for_user",
         AsyncMock(return_value=(theirs, "viewer")),
@@ -199,7 +180,7 @@ async def test_get_note_raises_when_not_found():
 async def test_get_note_treats_a_trashed_note_as_missing():
     """get_note_for_user resolves permission, not liveness — the trash filter is
     the caller's to apply."""
-    trashed = _fake_note(id=5)
+    trashed = fake_note(id=5)
     trashed.deleted_at = "2026-07-01T00:00:00Z"
     with patch(
         "scribe.mcp.tools.notes.notes_svc.get_note_for_user",
@@ -211,7 +192,7 @@ async def test_get_note_treats_a_trashed_note_as_missing():
 
 @pytest.mark.asyncio
 async def test_create_note_passes_through():
-    fake = _fake_note(id=10, title="new")
+    fake = fake_note(id=10, title="new")
     mock = AsyncMock(return_value=fake)
     with patch("scribe.mcp.tools.notes.notes_svc.create_note", mock):
         out = await create_note(title="new", body="x", tags=["a"], project_id=5)
@@ -223,7 +204,7 @@ async def test_create_note_passes_through():
 @pytest.mark.asyncio
 async def test_create_note_project_zero_becomes_none():
     """project_id=0 sentinel must become None at the service layer (orphan note)."""
-    fake = _fake_note()
+    fake = fake_note()
     mock = AsyncMock(return_value=fake)
     with patch("scribe.mcp.tools.notes.notes_svc.create_note", mock):
         await create_note(title="t", project_id=0)
@@ -234,7 +215,7 @@ async def test_create_note_project_zero_becomes_none():
 async def test_update_note_only_sends_non_default_fields():
     """Omitted (default) fields must NOT reach the service — otherwise they'd
     overwrite real data with empty strings."""
-    fake = _fake_note()
+    fake = fake_note()
     mock = AsyncMock(return_value=fake)
     with patch("scribe.mcp.tools.notes.notes_svc.update_note", mock):
         await update_note(note_id=1, title="new title")
@@ -247,7 +228,7 @@ async def test_update_note_only_sends_non_default_fields():
 @pytest.mark.asyncio
 async def test_update_note_empty_tags_clears_explicitly():
     """tags=[] is an explicit clear, distinct from tags=None (omit)."""
-    fake = _fake_note()
+    fake = fake_note()
     mock = AsyncMock(return_value=fake)
     with patch("scribe.mcp.tools.notes.notes_svc.update_note", mock):
         await update_note(note_id=1, tags=[])
@@ -256,7 +237,7 @@ async def test_update_note_empty_tags_clears_explicitly():
 
 @pytest.mark.asyncio
 async def test_update_note_tags_none_means_omit():
-    fake = _fake_note()
+    fake = fake_note()
     mock = AsyncMock(return_value=fake)
     with patch("scribe.mcp.tools.notes.notes_svc.update_note", mock):
         await update_note(note_id=1, tags=None)