LangGraph

LangChain's answer to 'agents need state machines, not chains.'

When to use it

Use this when your agent needs explicit branching, retries and cycles, and you're already in the LangChain ecosystem.

Microsoft's multi-agent conversation framework, one of the first to stick.

Role-based orchestration: give each agent a job title and a goal.

The agent scaffold built specifically to fix real GitHub issues.