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_snippets.py

@@ -2,32 +2,12 @@
 from unittest.mock import AsyncMock, MagicMock, patch
 
 import pytest
+from tests.helpers import FakeMCP, fake_snippet
 
 
 pytestmark = pytest.mark.usefixtures("_bind_user")
 
 
-def _fake_snippet(user_id: int = 7):
-    n = MagicMock()
-    n.id = 1
-    n.title = "debounce — rate-limit a callback"
-    n.body = "```js\nreturn 1\n```\n"
-    n.tags = ["js", "snippet"]
-    n.note_type = "snippet"
-    # Real int, matching the bound caller by default. The tools compare it to
-    # decide whether to attach a shared/owner marker; an auto-MagicMock would read
-    # as another user's record and send them off to look up a username.
-    n.user_id = user_id
-    # Explicitly None, not an auto-attribute: snippet_fields prefers `data` when
-    # truthy, and a MagicMock is truthy — every parsed field would come back as a
-    # MagicMock instead of a string.
-    n.data = None
-    n.to_dict.return_value = {
-        "id": 1, "title": n.title, "note_type": "snippet", "tags": n.tags,
-    }
-    return n
-
-
 @pytest.mark.asyncio
 async def test_create_snippet_requires_name_and_code():
     from scribe.mcp.tools.snippets import create_snippet
@@ -39,7 +19,7 @@ async def test_create_snippet_requires_name_and_code():
 
 @pytest.mark.asyncio
 async def test_create_snippet_records_and_returns_parsed():
-    created = _fake_snippet()
+    created = fake_snippet()
     with patch("scribe.services.dedup.find_duplicate_note", AsyncMock(return_value=None)), \
          patch("scribe.services.snippets.create_snippet",
                AsyncMock(return_value=created)) as mock_create:
@@ -88,7 +68,7 @@ async def test_update_snippet_missing_raises():
 async def test_update_snippet_empty_string_clears_a_field():
     # An omitted field must stay None ("leave alone"), but an explicit empty
     # string has to reach the service as "" so a stale field can be removed.
-    updated = _fake_snippet()
+    updated = fake_snippet()
     with patch("scribe.services.snippets.update_snippet",
                AsyncMock(return_value=updated)) as mock_update:
         from scribe.mcp.tools.snippets import update_snippet
@@ -101,7 +81,7 @@ async def test_update_snippet_empty_string_clears_a_field():
 @pytest.mark.asyncio
 async def test_update_snippet_project_id_conventions():
     from scribe.services import snippets as snippets_svc
-    updated = _fake_snippet()
+    updated = fake_snippet()
     cases = {0: snippets_svc.UNSET, -1: None, 5: 5}
     for given, expected in cases.items():
         with patch("scribe.services.snippets.update_snippet",
@@ -115,7 +95,7 @@ async def test_update_snippet_project_id_conventions():
 async def test_create_and_update_pass_locations_through():
     locs = [{"repo": "a", "path": "a.py", "symbol": "f"},
             {"repo": "b", "path": "b.py", "symbol": "g"}]
-    created = _fake_snippet()
+    created = fake_snippet()
     with patch("scribe.services.dedup.find_duplicate_note", AsyncMock(return_value=None)), \
          patch("scribe.services.snippets.create_snippet",
                AsyncMock(return_value=created)) as mock_create:
@@ -187,7 +167,7 @@ async def test_merge_snippets_requires_a_source():
 
 @pytest.mark.asyncio
 async def test_merge_snippets_returns_survivor_and_merged_ids():
-    survivor = _fake_snippet()
+    survivor = fake_snippet()
     with patch("scribe.services.snippets.merge_snippets",
                AsyncMock(return_value=(survivor, [2, 3]))) as mock_merge:
         from scribe.mcp.tools.snippets import merge_snippets
@@ -209,18 +189,10 @@ async def test_merge_snippets_not_found_raises():
 
 def test_register_attaches_all_tools():
     from scribe.mcp.tools import snippets
-    names: list[str] = []
+    mcp = FakeMCP()
 
-    class FakeMcp:
-        def tool(self, name):
-            names.append(name)
-
-            def deco(fn):
-                return fn
-            return deco
-
-    snippets.register(FakeMcp())
-    assert set(names) == {
+    snippets.register(mcp)
+    assert set(mcp.names) == {
         "list_snippets", "create_snippet", "get_snippet", "update_snippet",
         "delete_snippet", "merge_snippets", "verify_snippet",
         "find_duplicate_snippets", "unmerge_snippet",