test: the milestone result shape moved, and its fake had a mock for a body

test_milestone_search_is_its_own_shape asserts the result dict exactly, so
adding `matched` / `matched_is` / `body_length` broke it — which is the test
doing its job.

Its fake was a bare MagicMock, so `m.body` autovivified: `matched` came out as
a mock object and `body_length` as 0, and nothing in the old assertion touched
either. Lesson #2833 is about exactly this, and the failure output is what
surfaced it. The fake now carries a real body string and a report with the
chunk that matched, so the assertion is about the product rather than about
MagicMock's attribute behaviour.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01821k5B3Ysecp9fNYs92Kuy

tests/test_mcp_tool_search.py

@@ -211,16 +211,36 @@ async def test_milestone_search_is_its_own_shape_and_scopes_to_the_project():
     from unittest.mock import MagicMock
 
     _user_id_ctx.set(7)
+    # `body` is a REAL string, not left to MagicMock's attribute autovivication:
+    # the result now reads it, and a mock body would make `matched` a mock
+    # object and `body_length` zero while the assertion still looked green
+    # (lesson #2833).
     ms = MagicMock(id=339, title="M3 — Metadata", description="works, editions",
-                   status="active", project_id=30)
-    found = AsyncMock(return_value=[(0.81, ms)])
+                   status="active", project_id=30,
+                   body="Step 4 — the metadata editions table.")
+
     summary = AsyncMock(return_value=[{"id": 339, "total": 0, "completed": 0}])
-    with patch("scribe.mcp.tools.search.semantic_search_milestones", found), \
+    seen: dict = {}
+
+    async def _milestone_search(*_a, **kw):
+        seen.update(kw)
+        kw["report"]["best_chunk"] = {
+            339: {"index": 1, "text": "Step 4 — the metadata editions table."}
+        }
+        return [(0.81, ms)]
+
+    with patch("scribe.mcp.tools.search.semantic_search_milestones",
+               _milestone_search), \
          patch("scribe.services.milestones.get_project_milestone_summary", summary):
         out = await search(q="book metadata", content_type="milestone", project_id=30)
-    assert found.await_args.kwargs["project_id"] == 30
+    assert seen["project_id"] == 30
     assert out["results"] == [{
         "id": 339, "title": "M3 — Metadata", "description": "works, editions",
+        # The plan body stays out; the passage that matched comes along, and
+        # says which of the two it is (#4243).
+        "matched": "Step 4 — the metadata editions table.",
+        "matched_is": "matched_passage",
+        "body_length": len("Step 4 — the metadata editions table."),
         "status": "active", "project_id": 30, "total": 0, "completed": 0,
         "similarity": 0.81,
     }]