State Machine¶

Stable ID: pattern.state-machine
Kind: design-pattern
Status: stable
Source: skill/references/design-patterns/state-machine.md

Purpose¶

Model allowed states, events, guards, and transitions explicitly when lifecycle behaviour is non-trivial.

Use when¶

• Illegal transitions must be prevented and explained.
• Concurrent or long-lived workflows have observable lifecycle states.

Avoid when¶

• There are only two obvious states with no transition rules.
• A large framework obscures a small enum and match statement.

Applicability¶

• Languages: any, python, q-kdbplus, cpp, rust, dart-flutter, typescript
• Related entries: example.explicit-state-machine, pattern.command