Workflow Design

Before designing: What are the business states? What events trigger transitions? What invariants? What can fail?

After designing: Is every state reachable? Can every state exit? Are guards mutually exclusive? Are error states recoverable?

Invariant Principles

1. States Are Business Concepts: "ProcessingPayment" not "step3"
2. Transitions Are Events: Every arrow needs a named trigger
3. Guards Prevent Ambiguity: Mutually exclusive and exhaustive
4. Error States Are First-Class: Every state needs an error path
5. Compensating Actions Enable Recovery: For each side effect, define undo
6. Invariants Are Explicit: Violations are bugs, not edge cases
7. Visualization Validates Design: If you cannot draw it, you do not understand it