Add Langfuse as a self-hosted eval and trace viewer

apps/ai-service/tests/test_api.py

@@ -162,6 +162,66 @@ def test_history_rejects_an_oversized_conversation_id_before_querying_storage():
     assert traces.calls == []
 
 
+def test_transcript_returns_user_and_assistant_turns_oldest_first():
+    when = datetime(2026, 8, 14, 10, 0, tzinfo=timezone.utc)
+    traces = FakeHistoryTraceWriter({
+        # list_by_conversation contract is newest-first, same as /history.
+        "case-1": [
+            RetrievalTrace(
+                trace_id="t2", query="Chống chỉ định metformin?",
+                subject_scope="human", intent="fact_lookup",
+                decision="answerable", reason="grounded_evidence_available",
+                resolved_drug_id="metformin", citations=(),
+                conversation_id="case-1", created_at=when,
+                response_payload={
+                    "answer": "Suy thận nặng.",
+                    "resolved_drug_id": "metformin",
+                    "citations": [{"chunk_id": "metformin::cci::0"}],
+                    "generated": True,
+                    "quick_replies": [],
+                    "blocks": [],
+                    "answer_mode": "concise",
+                    "answer_plan": None,
+                    "candidate_assessments": [],
+                    "disclaimer": "disclaimer text",
+                },
+            ),
+            RetrievalTrace(
+                trace_id="t1", query="Chỉ định metformin?",
+                subject_scope="human", intent="fact_lookup",
+                decision="answerable", reason="grounded_evidence_available",
+                resolved_drug_id="metformin", citations=(),
+                conversation_id="case-1", created_at=when,
+                response_payload=None,
+            ),
+        ],
+    })
+    app = create_app(settings=Settings(), trace_writer=traces)
+
+    response = TestClient(app).get("/v1/rag/transcript", params={"conversation_id": "case-1"})
+
+    assert response.status_code == 200
+    body = response.json()
+    # t1 (oldest) has no persisted answer -> user turn only. t2 has one -> both.
+    roles = [(m["trace_id"], m["role"]) for m in body["messages"]]
+    assert roles == [("t1", "user"), ("t2", "user"), ("t2", "assistant")]
+    assistant = body["messages"][2]
+    assert assistant["content"] == "Suy thận nặng."
+    assert assistant["citations"] == [{"chunk_id": "metformin::cci::0"}]
+    assert assistant["generated"] is True
+
+
+def test_transcript_with_empty_conversation_id_returns_no_messages():
+    traces = FakeHistoryTraceWriter({})
+    app = create_app(settings=Settings(), trace_writer=traces)
+
+    response = TestClient(app).get("/v1/rag/transcript", params={"conversation_id": "  "})
+
+    assert response.status_code == 200
+    assert response.json() == {"messages": []}
+    assert traces.calls == []
+
+
 def test_health_and_fail_closed_rag_response_are_traced():
     traces = MemoryTraceWriter()
     app = create_app(
@@ -324,6 +384,35 @@ def test_query_routes_through_the_agent_when_one_is_configured():
     assert agent.calls == [("Liều metformin?", "c1", "ai")]
 
 
+def test_query_persists_the_full_answer_for_later_transcript_replay():
+    """The `/transcript` endpoint can only redraw a conversation if this
+    survives to storage — a plain trace row (decision/reason only) is not
+    enough to show what the AI actually said."""
+    agent = FakeAgent(AgentReply(
+        decision="answerable", reason="grounded_evidence_available",
+        answer="Liều 500 mg [1].", citations=(_citation(),),
+        drugs=("metformin",), turn_type="drug_attribute", generated=True,
+    ))
+    traces = MemoryTraceWriter()
+    app = create_app(
+        settings=Settings(),
+        answer_service=GroundedAnswerService(FixedRouting()),
+        conversational=agent,
+        trace_writer=traces,
+    )
+    TestClient(app).post("/v1/rag/query", json={
+        "query": "Liều metformin?", "subject_scope": "human",
+        "intent": "fact_lookup", "conversation_id": "c1",
+    })
+
+    payload = traces.rows[-1]["response_payload"]
+    assert payload["answer"] == "Liều 500 mg [1]."
+    assert payload["resolved_drug_id"] == "metformin"
+    assert payload["generated"] is True
+    assert len(payload["citations"]) == 1
+    assert payload["citations"][0]["chunk_id"] == "metformin::lieu::0"
+
+
 def test_query_forwards_monograph_response_mode_to_agent():
     agent = FakeAgent(AgentReply(
         decision="clarify",