How to achieve nested tracing across SERVERS

LangSmith Product Help Observability & Evals
1

Can anyone guide me on how to nested-
across servers. Here is a sample code
I have using but it is not giving a nested-
trace.
https://drive.google.com/file/d/1eBoH2fo98avuPRz4fiiXwzMsqZMNqAmL/view?usp=sharing

4