Agent workflow dependency graph

[yanxi0830]

🚀 Describe the new functionality needed

We want to be able to keep track of message passing flow in multi-agent workflows. e.g. https://github.com/meta-llama/llama-stack/blob/main/docs/notebooks/Llama_Stack_Agent_Workflows.ipynb

1/ expose api to keep track of upstream metadata in agent create turn 2/ functionality in backend agents to build dependency graph 3/ ability to query dependency graph for session & message history within a workflow

💡 Why is this needed? What if we don't build it?

better multi-agent workflow monitoring

Other thoughts

No response