feat: improve input/output detection for traces in the langwatch integration

[0xdeafcafe]

Hey, I'm an engineer at @langwatch. This PR improves the input/output detection for traces when the langwatch integration is enabled.

Related issue: #6909

[codspeed-hq]

CodSpeed Performance Report

Merging #7067 will improve performances by 15.66%

_{Comparing 0xdeafcafe:improve/langwatch-tracing-input-output-detection (f045712) with main (4d9138f)}

Summary

⚡ 2 improvements
✅ 17 untouched benchmarks

Benchmarks breakdown

	Benchmark	BASE	HEAD	Change
⚡	test_build_flow_invalid_job_id	9.3 ms	8.3 ms	+11.61%
⚡	test_cancel_build_success	248.7 ms	215 ms	+15.66%

[Copilot]

Pull Request Overview

This PR enhances the langwatch integration by refining how input/output data for traces is detected and updated. The changes add conditional updates for the root trace span based on the sender of the inputs.

• Update root span input when the sender is "User"
• Update root span output when the sender is "Machine"

[italojohnny]

Hey, @0xdeafcafe ! How’s it going?

I tried running your PR locally and got the following exception:

ValueError: No current trace found, could not get_current_trace(), make sure you added a @langwatch.trace() decorator
on your LLM pipeline top-level function

The current code on the main branch doesn’t throw this exception, so I’m guessing something’s off. Could you clarify what might be happening?