Defining Router Logic

Sometimes a simple status-to-status transition isn't enough.
You may want to route actions conditionally based on context, payload, or shared state.

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🧠 What is Router Logic?

Router logic lets you override or extend transitions using:

• Contextual conditions (ctx.state, ctx.sv, etc.)
• Action payloads
• Runtime data

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🔀 Example: Conditional Transition

const transitionSelectors = {
  idle: {
    increment: ({ ctx, payload }) => {
      return ctx.state.count >= 5 ? 'cooldown' : 'incrementing';
    },
  },
};

This overrides the static transition and dynamically decides where to go.

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🧪 Use Case Scenarios

Use Case	Example
Form validation	Go to error if ctx.state.valid === false
API throttling	Go to cooldown if call limit exceeded
Dynamic branching	Route based on payload flag

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⚠️ Things to Watch Out For

• Avoid side effects inside routing logic
• Always return a valid status string
• Consider fallback/default transitions

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🔗 Related Config Field

This logic is usually passed to createMachineConfig() as:

createMachineConfig({
  ...transitionSelectors,
});

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