Pregel

Shows how to resume a LangGraph stream after a custom human_assistance tool calls interrupt(). Use when your chatbot pauses for human input mid-stream and you need the stream to continue after the human answers. Requires a checkpointer; res

Explains LangGraph's interrupt_after semantics: it fires after the node AND its outgoing edges run. Use when interrupt_after seems to trigger at the wrong time or your conditional edge runs before the pause. Fixed by switching to interrupt_

Explains LangGraph's "Found edge starting at unknown node" validation error. Use when graph.compile() or validate() raises it. It means an edge references a node name that was never added, usually a typo. Fix the name; every edge source mus