feat(token-tracking): attach usage hook to advisor's self-created LLM client

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

tests/test_advisor_llm_analyzer.py

@@ -132,6 +132,39 @@ def test_analyze_does_not_close_injected_client() -> None:
     assert fake.closed is False
 
 
+def test_analyze_attaches_usage_hook_to_self_created_client(monkeypatch) -> None:
+    """A self-created client gets the token-usage hook attached (not the injected-client path)."""
+    captured: dict = {}
+    fake = _FakeClient(captured)
+    hook_calls = []
+
+    import openai
+    import rag_eval.metrics.factory as factory_mod
+
+    monkeypatch.setattr(openai, "AsyncOpenAI", lambda **kwargs: fake)
+    monkeypatch.setattr(
+        factory_mod, "resolve_openai_client_kwargs", lambda *a, **k: {"api_key": "x"}
+    )
+    monkeypatch.setattr(factory_mod, "attach_usage_hook", lambda c: hook_calls.append(c))
+
+    asyncio.run(analyze([_diagnosis()], "scn", "gpt-4o", _Settings()))
+
+    assert hook_calls == [fake]
+
+
+def test_analyze_does_not_attach_hook_for_injected_client() -> None:
+    """An injected chat_client is assumed to already have the hook attached by its owner."""
+    hook_calls = []
+    import rag_eval.metrics.factory as factory_mod
+    import unittest.mock as mock
+
+    with mock.patch.object(factory_mod, "attach_usage_hook", lambda c: hook_calls.append(c)):
+        fake = _FakeClient({})
+        asyncio.run(analyze([_diagnosis()], "scn", "gpt-4o", _Settings(), chat_client=fake))
+
+    assert hook_calls == []
+
+
 def test_is_reasoning_model_detection() -> None:
     assert _is_reasoning_model("gpt-5")
     assert _is_reasoning_model("gpt-5.5")