Agent Orchestration Explained
Agents as graphs, steps and checkpoints.
An interactive guide to agents as graphs: steps, checkpoints, multi-agent patterns and durable runs, on an engine checked against LangGraph.
How this is checkedEach of 39 sessions also runs in real LangGraph 1.2.14, and after every one of 71 operations its whole checkpoint history equals the engine's. How it is tested →
What you'll learn
A multi-step agent is a discrete-event system: nodes run in steps, write to a shared state, wait at barriers, save checkpoints, pause for people, crash and resume. This site takes LangGraph's execution model apart, super-step by super-step, and then durable execution: replaying a workflow's history after a crash without paying for its side effects twice. Then it scales up: multi-agent patterns compared on one task, fan-out against a rate limit, reliability with retries and verifiers, hundreds of workflows sharing one endpoint, and a pattern chosen from the simulation rather than from opinion.
The animations are driven by Agent_Loop_Sim's orchestration module, identically in Python and in your browser. Its graph runtime is checked against real LangGraph 1.2.14 in CI: 39 sessions, 71 operations (runs, crashes, resumes, interrupts, edits, time travel, Send fan-outs) and 232 checkpoints, every one equal. No language model runs anywhere.
01
From a chain to a graph
A request flowing through a graph, super-step by super-step: nodes light up together, writes wait at a barrier, state flows along the edges, and a step lasts as long as its slowest node.
02
State, channels and reducers
Two parallel branches write the same key: no reducer is an error, an add reducer keeps both in a fixed order, a custom reducer picks one; and what a router can see.
03
Checkpoints and interrupts
A checkpoint after every super-step: a run that crashes and resumes, a human interrupt, an edit, and time travel that forks the thread, on a timeline of checkpoints.
04
Durable execution
An event history replayed after a crash: recorded steps are not run again, a step that reads the clock breaks the replay, and an idempotency key stops a double charge.
05
Multi-agent patterns
Single agent, supervisor, hierarchical, swarm, debate and map-reduce on the same task: every call on a timeline, each agent's context, and what each pattern costs in tokens, time and reliability.
06
Fan-out and map-reduce
Parallel workers under a rate limit: watch calls queue for token capacity and the speed-up saturate, against Amdahl's law and the bound the token bucket sets.
07
Reliability
Success decays with every step; retries fix visible errors, a verifier catches silent ones. The closed forms beside seeded simulations and their confidence intervals.
08
Running at scale
Hundreds of workflows sharing one rate-limited endpoint: queueing, tail latency, retries and cost per successful task, and the knee where load meets capacity.
09
Choosing a pattern
A decision guide built from the simulation: set constraints on success, latency, cost and throughput, and watch them strike out patterns until one is left.
Part of a family of sixteen companion sites in four tracks, all in the site menu above: Foundations (Decoder, Training), Hardware (Kernels, Systolic, Accelerators, Racks), Inference (Serving, Architectures, Numerics, Trade-offs) and Agents (Harnesses, Protocols, Context, Orchestration, Evals, Security). It is the fourth of the six agent sites. How this one was built, and how to check it: about.