What does createMachine give you?

Ben

So... declaring the machine and running it are separate things, right? Then... couldn't we run several independent machines from a single declaration?

Exactly, Ben. createMachine gives you back a plain object — a blueprint. Let me build it. We wrap everything in createMachine. It always starts with initial: 'idle' — the machine always powers on there. Then we add the states map and fill in every rule we wrote across the last few episodes.

Look at the blueprint — for the first time, nothing is lit. No timers, no fetches. Nothing is running.

And that means one machine can power many running copies at once. We can spin up actor one, actor two, actor three — each holding its own state, none aware of the others. The blueprint itself never changes. Each running copy is called an actor.

What makes it run?

createActor wraps the machine in an actor — a separate thing, with a mailbox for events and a stream of snapshots. Not running yet — just built.

That snapshot stream is for subscribers. Anyone can subscribe to the actor — the UI, a logger, a test. We subscribe first, so we don't miss a single snapshot — in our case, we'll just console log it.

Now, call .start() — and the actor comes alive: its current state is idle, and the first snapshot goes out. The actor runs; subscribers watch.

Send SAVE. It lands in the mailbox. The actor looks up the rule on the blueprint — idle has one for SAVE. It fires, and a new snapshot goes out: saving.

Send SUCCESS. Same loop: saving has a rule for it. It fires, and another snapshot goes out — saved.

The machine is the plan — every possible path, written down before anything runs. The actor is the plan, running. And with that, every piece is on the table: states, events, context, guards, actions, actors. Time to see them all in one picture.