refactor(tests): per-model fakes, FakeMCP and session mocks come from tests/helpers (#2825, milestone 296 area 1, batch 2)

Second pass over the tests/ ledger after bbee0d0. fake_record(**attrs) is the
one MagicMock-with-real-attributes builder (to_dict mirrors them; the
note-2109 hazard documented once); fake_note/fake_task/fake_snippet/
fake_project/fake_milestone/fake_system/fake_rulebook/fake_topic/fake_rule
carry each model's ordinary defaults on top of it, replacing 14 per-file
factories (two rulebook trios in tool-vs-service wordings, _fake_task, _fake_ms,
_fake_project, _plan_note, _fake_snippet, two _snippet adapters now one-liners
over fake_snippet). FakeMCP replaces the five closure-over-a-list registrar
fakes (+ _Recorder); loc() and design_token_stub() replace the paired _loc /
_token / _T stand-ins; every hand-built async_session mock (9 helper defs and
14 inline copies) now starts from make_mock_session(). Call sites rewritten by
AST with each file's former defaults made explicit, so behaviour is unchanged.

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

tests/test_mcp_tool_planning.py

@@ -1,6 +1,7 @@
-from unittest.mock import AsyncMock, MagicMock, patch
+from unittest.mock import AsyncMock, patch
 
 import pytest
+from tests.helpers import fake_task
 
 
 pytestmark = pytest.mark.usefixtures("_bind_user")
@@ -18,25 +19,12 @@ async def test_start_planning_tool_delegates_to_service():
     assert mock.call_args.kwargs == {"user_id": 7, "project_id": 3, "title": "Plan it"}
 
 
-def _plan_note(task_kind: str):
-    note = MagicMock()
-    note.parent_id = None
-    note.project_id = 3
-    note.id = 9
-    # Real values — get_task reads deleted_at and compares user_id to the bound
-    # caller, and a MagicMock is truthy on both (note 2109).
-    note.user_id = 7
-    note.deleted_at = None
-    note.to_dict.return_value = {"id": 9, "task_kind": task_kind, "project_id": 3}
-    return note
-
-
 @pytest.mark.asyncio
 async def test_get_task_augments_plan_with_rules():
     applicable = {"rules": [{"id": 1, "title": "r"}], "truncated": False,
                   "subscribed_rulebooks": [{"id": 2, "title": "rb"}]}
     with patch("scribe.mcp.tools.tasks.notes_svc.get_note_for_user",
-               AsyncMock(return_value=(_plan_note("plan"), "owner"))), \
+               AsyncMock(return_value=(fake_task(task_kind="plan", id=9, project_id=3), "owner"))), \
          patch("scribe.mcp.tools.tasks.rulebooks_svc.get_applicable_rules",
                AsyncMock(return_value=applicable)):
         from scribe.mcp.tools.tasks import get_task
@@ -49,7 +37,7 @@ async def test_get_task_augments_plan_with_rules():
 @pytest.mark.asyncio
 async def test_get_task_work_kind_has_no_rules():
     with patch("scribe.mcp.tools.tasks.notes_svc.get_note_for_user",
-               AsyncMock(return_value=(_plan_note("work"), "owner"))), \
+               AsyncMock(return_value=(fake_task(task_kind="work", id=9, project_id=3), "owner"))), \
          patch("scribe.mcp.tools.tasks.rulebooks_svc.get_applicable_rules",
                AsyncMock()) as mock_rules:
         from scribe.mcp.tools.tasks import get_task