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_systems.py

@@ -2,21 +2,14 @@
 from unittest.mock import AsyncMock, MagicMock, patch
 
 import pytest
-from tests.helpers import fake_note
-
-
-def _fake_system(sid=1, name="Reader", project_id=5):
-    s = MagicMock()
-    s.to_dict.return_value = {"id": sid, "name": name, "project_id": project_id}
-    s.project_id = project_id
-    return s
+from tests.helpers import fake_note, fake_system
 
 
 @pytest.mark.asyncio
 async def test_create_system_returns_dict():
     with patch("scribe.mcp.tools.systems.current_user_id", return_value=1), \
          patch("scribe.mcp.tools.systems.systems_svc") as svc:
-        svc.create_system = AsyncMock(return_value=_fake_system(name="Reader"))
+        svc.create_system = AsyncMock(return_value=fake_system(name="Reader"))
         from scribe.mcp.tools.systems import create_system
         result = await create_system(project_id=5, name="Reader", description="pdf reader")
     assert result["name"] == "Reader"
@@ -39,7 +32,7 @@ async def test_get_system_splits_records_by_kind():
     note = MagicMock(); note.to_dict.return_value = {"id": 12}; note.task_kind = "work"; note.status = None
     with patch("scribe.mcp.tools.systems.current_user_id", return_value=1), \
          patch("scribe.mcp.tools.systems.systems_svc") as svc:
-        svc.get_system = AsyncMock(return_value=_fake_system(sid=3))
+        svc.get_system = AsyncMock(return_value=fake_system(id=3))
         svc.list_records_for_system = AsyncMock(return_value=[issue, work, note])
         from scribe.mcp.tools.systems import get_system
         result = await get_system(system_id=3)
@@ -164,7 +157,7 @@ async def test_populated_vocabulary_never_counts_records():
 
 @pytest.mark.asyncio
 async def test_create_system_same_normalized_name_is_duplicate_gated():
-    existing = _fake_system(sid=7, name="Scrape Pipeline")
+    existing = fake_system(id=7, name="Scrape Pipeline")
     existing.id = 7
     existing.name = "Scrape Pipeline"
     with patch("scribe.mcp.tools.systems.current_user_id", return_value=1), \
@@ -180,12 +173,12 @@ async def test_create_system_same_normalized_name_is_duplicate_gated():
 
 @pytest.mark.asyncio
 async def test_create_system_distinct_name_passes_the_gate():
-    other = _fake_system(sid=7, name="Workers")
+    other = fake_system(id=7, name="Workers")
     other.name = "Workers"
     with patch("scribe.mcp.tools.systems.current_user_id", return_value=1), \
          patch("scribe.mcp.tools.systems.systems_svc") as svc:
         svc.list_systems = AsyncMock(return_value=[other])
-        svc.create_system = AsyncMock(return_value=_fake_system(sid=8, name="Exporter"))
+        svc.create_system = AsyncMock(return_value=fake_system(id=8, name="Exporter"))
         from scribe.mcp.tools.systems import create_system
         result = await create_system(project_id=5, name="Exporter")
     assert result["name"] == "Exporter"