Summary

Closes #210: Removes hard dependency on Langfuse for /threads and /response, allowing use with only OpenAI credentials.

Fixes #249: Eliminates race conditions caused by shared langfuse_context across async requests and background jobs.

Closes #244: Brings tracing to /responses, ensuring consistent Langfuse session grouping.

Key Changes:

• Introduced LangfuseTracer, a modular tracing utility that conditionally activates based on credentials.
• Context is now thread-safe: each request and scheduled job maintains its own tracer instance.
• Ensured compatibility: Langfuse tracing is bypassed if credentials are not configured.
• Set session_id = thread_id to logically group traces per conversation thread.

Grouping of traces in Response API

To group traces by conversation:

• For the first response in a conversation, we generate a new session_id and associate it with the trace and we will add tag to this trace which is response_id . For subsequent responses in the same conversation:
• We query tags in Langfuse traces using the previous response_id to fetch the trace metadata.
• From this metadata, we extract the associated session_id.
• The new trace for the current response is then assigned the same session_id, effectively grouping all related traces under the same conversation session.

Checklist

• Ran fastapi run --reload app/main.py or docker compose up in the repository root and test.
• If you've fixed a bug or added code that is tested and has test cases.

Notes

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