Concepts

Each page is a focused take on one idea. Read top-to-bottom for a tour of the framework, or jump to whichever concept you need.

• State and reducers — typed state, per-field merge policies, what makes nodes safe to write.
• Graphs: nodes, edges, build, invoke — the four moves you make to turn a state schema into a runnable pipeline.
• Composition: conditional edges, subgraphs, projection — routing decisions, encapsulated sub-pipelines, the parent ↔ subgraph data seam.
• Fan-out — running the same subgraph many times in parallel, results merged back deterministically.
• Observability — node-boundary hooks, OTel mapping, log correlation.
• Checkpointing — save state at each node boundary, resume from a prior point.

If you're brand-new, Quickstart is the faster entry — under a minute to a running graph. Come back here when you want to know why things are shaped the way they are.