observability-context-propagation-using-fastapi-streamingresponse-with-tracing-libra-d1fc4858

THEN Capture the current tracing context (e.g., via contextvars.copy_context()) before starting the streaming response, then restore that context inside the async generator at each yield. Alternatively, use FastAPI's lifespan or middleware to ensure context is properly propagated across coroutine boundaries.

from contextvars import copy_context
async def streaming_response():
    ctx = copy_context()
    async for chunk in async_generator:
        ctx.run(restore_trace_context)
        yield chunk