I’m facing issues while logging traces in LangSmith with a setup that involves a Host Agent built using ADK and a Remote Agent built using LangGraph. These agents communicate via the Agent-to-Agent (A2A) protocol.
Problems observed:
- Broken traces between Host Agent (ADK) and Remote Agent (LangGraph):
- When the Host Agent (implemented using the Agent Development Kit - ADK) calls the Remote Agent (implemented in LangGraph) through A2A, the traces are broken.
- Instead of a single end-to-end trace, I see fragmented traces for the Host Agent and the Remote Agent separately, making it hard to correlate the full chain of execution.
- Subsequent API calls result in incomplete traces:
- The first time I hit the API, the trace logs correctly and shows up in LangSmith as expected.
- However, on any subsequent calls, the request keeps loading and the trace remains incomplete in LangSmith — it never finalizes.
Additional context:
- When I run similar traces entirely within LangGraph (end-to-end), the traces log perfectly.
- So this issue seems specific to the ADK Host → LangGraph Remote scenario when connected via the A2A protocol.
Expected behavior:
- Traces should be continuous and automatically linked between the Host Agent (ADK) and Remote Agent (LangGraph).
- Every API call should produce a complete trace consistently, not just the first call.