fix(langfuse): v4 가 옛 ingestion 을 거부 — OTLP/HTTP JSON(/api/public/otel/v1/traces)으로 전환, 로컬 Langfuse 실측 통과. 사용자·세션 속성은 자식 span 에도 복사

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

5_django_backend/tests/test_gateway.py

@@ -133,13 +133,16 @@ async def test_stream_reports_generation_to_langfuse(upstream, monkeypatch):
     from apps.gateway import langfuse
 
     got = []
-    monkeypatch.setattr(langfuse, "TRANSPORT", httpx.MockTransport(lambda r: (got.append(json.loads(r.content)), httpx.Response(207, json={}))[1]))
+    monkeypatch.setattr(langfuse, "TRANSPORT", httpx.MockTransport(lambda r: (got.append(json.loads(r.content)), httpx.Response(200, json={}))[1]))
     upstream(lambda r: _sse(b'data: {"choices":[{"delta":{"content":"hi"}}],"usage":{"prompt_tokens":2,"completion_tokens":1}}\n\ndata: [DONE]\n\n'))
     resp = await _post({"model": "581", "stream": True, "messages": [{"role": "user", "content": "q"}]})
     b"".join([c async for c in resp.streaming_content])
     await asyncio.gather(*list(langfuse._pending))
-    gen = got[0]["batch"][1]["body"]
-    assert gen["model"] == "581" and gen["output"] == "hi" and gen["usage"]["total"] == 3 and gen["input"][0]["content"] == "q"
+    spans = got[0]["resourceSpans"][0]["scopeSpans"][0]["spans"]
+    ga = {a["key"]: a["value"].get("stringValue") for a in spans[1]["attributes"]}
+    assert ga["langfuse.observation.model.name"] == "581" and ga["langfuse.observation.output"] == "hi"
+    assert json.loads(ga["langfuse.observation.usage_details"])["total"] == 3
+    assert json.loads(ga["langfuse.observation.input"])[0]["content"] == "q"
 
 
 @override_settings(FABRIX_ENV=FULL_ENV)