In my experience the approach matters a lot, I recently implemented Otel with Claude Code in a medium sized ~200k loc project:

- initially it wasn't working, plenty of parent/child relationships problems like described in the post

- so I designed a thin a wrapper and used sealed classes for events instead of dynamic spans + some light documentation

It took me like a day to implement tracing on the existing codebase, and for new features it works out of the box using the documentation.

At the end of the day, leveraging typing + documentation dramatically constrains LLMs to do a better job

I had issues in the beginning, now it works fine, Claude is using it all the time to find things in my codebase.

Thanks for the tip. I was dubious, I tried GPT 5.2 for a start on a large plan and it was way better than reviewing it with Claude itself or Gemini. I then used it to help me with feature I was reviewing, it caught real discrepancies between the plan and the actual integration!