Why there is not on_agent_start callback?

[wuodar]

As in the title. I can't find it anywhere. Is it on purpose? If yes - why?

[hinthornw]

What do you hope to accomplish with an on_agent_start callback?

The on_chain_start event is triggered at each node - does that work for you?

[wuodar]

Yes, thanks!

Is somwhere some more in-depth description of langgraph constructs and how are they compiled to (and which) langchain constructs?
Before your answer I didn't know that node is a chain from the langchain perspective.