test(retrieval): two source guards read the pipeline where the rule arms now live (milestone 456 step 2, #4904)

CI run 8137 had two failures, both source-scanning guards whose property
moved to the pipeline. The property itself still held:

- test_every_surface_name_is_a_real_telemetry_source looked for
  source="<name>" literals. The rule arms now record under their spec field,
  so the spec is the join key, read from RULE_ARMS.
- test_every_hook_rule_search_says_which_project_it_is_for counted 4 direct
  searches in plugin_context. It now expects 0 there, so a copied arm fails
  the count. It also asserts that the pipeline has exactly one search and
  that its keyword literal carries project_id and never everywhere.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

tests/test_rule_usage_wiring.py

@@ -1698,7 +1698,10 @@ def test_every_hook_rule_search_says_which_project_it_is_for():
     `everywhere` is not an acceptable answer in a hook, which speaks unasked.
     """
     sources = {
-        "src/scribe/services/plugin_context.py": 4,
+        # Since milestone 456 the hook arms search through the pipeline's one
+        # ranked-search stage, checked below — so a direct search appearing
+        # here again is a copy of the arm coming back, and fails the count.
+        "src/scribe/services/plugin_context.py": 0,
         "src/scribe/services/reply_preferences.py": 1,
     }
     for path, expected in sources.items():
@@ -1724,6 +1727,31 @@ def test_every_hook_rule_search_says_which_project_it_is_for():
                 f"{path}:{call.lineno} searches every project's rules from a hook"
             )
 
+    # The pipeline: exactly one search, in `_ranked`, whose keyword set is
+    # built as a dict literal — so the keys are read from that literal.
+    pipeline = ast.parse(Path("src/scribe/services/retrieval_pipeline.py").read_text())
+    searches = [
+        n for n in ast.walk(pipeline)
+        if isinstance(n, ast.Call) and getattr(n.func, "attr", None) == "search"
+    ]
+    assert len(searches) == 1, (
+        f"the pipeline has {len(searches)} rule searches, expected 1 — every "
+        f"arm is meant to reach the ranker through `_ranked`"
+    )
+    ranked = next(n for n in ast.walk(pipeline)
+                  if isinstance(n, ast.AsyncFunctionDef) and n.name == "_ranked")
+    keys = {
+        k.value for d in ast.walk(ranked) if isinstance(d, ast.Dict)
+        for k in d.keys if isinstance(k, ast.Constant)
+    }
+    assert "project_id" in keys, (
+        "the pipeline's rule search no longer passes project_id, so every hook "
+        "arm gets global rules only and never its own project's"
+    )
+    assert "everywhere" not in keys and not any(
+        isinstance(n, ast.keyword) and n.arg == "everywhere" for n in ast.walk(ranked)
+    ), "the pipeline searches every project's rules from a hook"
+
 
 @pytest.mark.asyncio
 @pytest.mark.parametrize("bound, scope", [(7, 7), (0, None)])