- LangGraph — agents as explicit state graphs with nodes, edges, checkpointing, and human-in-the-loop interrupts. Best when you need durable, resumable, auditable workflows. - CrewAI — role-based crews (`role`, `goal`, `backstory`) with sequential or hierarchical processes. Fast to express "team of specialists" products. - AutoGen / AG2 — conversation-centric multi-agent chat, strong for code-executing agents in sandboxes. - LlamaIndex — retrieval-first agents over indexed corpora. - Agno, CAMEL, AWS Strands — lightweight or provider-aligned runtimes.
python
from langgraph.graph import StateGraph, END
g = StateGraph(State)
g.add_node("plan", plan_node)
g.add_node("act", act_node)
g.add_conditional_edges("act", lambda s: "act" if s["pending"] else END)
g.set_entry_point("plan")
app = g.compile(checkpointer=saver) # resumable across process restartsAdopt a framework for what is genuinely hard: durable state, checkpoint/resume, human approval gates, and tracing. A single-tool assistant does not need one — a 60-line loop is easier to debug and cheaper to run.
Exercise: rebuild your loop in LangGraph with a checkpointer, kill the process mid-run, and resume from the last checkpoint.