State Machine Skill

Document the state machine for UI components, comparing current behavior to expected behavior and mapping all state transitions.

When to Use

• During Ask mode CONVERGE loop for stateful components
• When refactoring existing components with complex state
• Before implementing new interactive UI components

Instructions

Phase 1: Identify States

List all possible states for the component:

State	Current Behavior	Expected Behavior
Initial	[What happens now]	[What should happen]
Loading	[Current loading UX]	[Expected loading UX]
Success	[Current success display]	[Expected success display]
Error	[Current error handling]	[Expected error handling]
Empty	[Current empty state]	[Expected empty state]

Common States to Consider:

State Type	Examples
Data states	Initial, Loading, Success, Error, Empty, Stale
Interaction states	Idle, Hover, Focus, Active, Disabled
Visibility states	Hidden, Visible, Collapsed, Expanded
Selection states	Unselected, Selected, Partially selected
Validation states	Valid, Invalid, Pending validation

Phase 2: Map Transitions

Define what triggers each state change:

From	To	Trigger	Side Effects
Initial	Loading	User action / Mount	Start fetch
Loading	Success	Data received	Populate UI
Loading	Error	Request failed	Show error message
Loading	Empty	Empty response	Show empty state
Error	Loading	Retry clicked	Restart fetch
Success	Loading	Refresh clicked	Refetch data

Phase 3: State Diagram

Create a Mermaid state diagram:

stateDiagram-v2
    [*] --> Initial
    Initial --> Loading : fetch
    Loading --> Success : data received
    Loading --> Error : request failed
    Loading --> Empty : no data
    Error --> Loading : retry
    Success --> Loading : refresh
    Empty --> Loading : refresh
    Success --> [*] : unmount

Phase 4: Data Requirements

For each state, define what data is needed:

State	Required Data	UI Elements
Initial	None	Placeholder or skeleton
Loading	None	Spinner, skeleton, progress
Success	[List required fields]	Full component
Error	Error message, retry action	Error banner, retry button
Empty	Empty message, CTA	Empty illustration, CTA button

Phase 5: Edge Cases

Identify edge cases and how to handle:

Edge Case	Current	Expected
Network timeout	[Current]	Show timeout message, retry option
Partial data	[Current]	Graceful degradation, show available
Stale data	[Current]	Show stale indicator, background refresh
Concurrent updates	[Current]	Optimistic update, rollback on conflict
Auth expired	[Current]	Redirect to login, preserve state

Output Format

## State Machine: [Component Name]

### State Table

| State | Current | Expected | Data Required |
|-------|---------|----------|---------------|
| Initial | [Behavior] | [Behavior] | [Data] |
| Loading | [Behavior] | [Behavior] | [Data] |
| Success | [Behavior] | [Behavior] | [Data] |
| Error | [Behavior] | [Behavior] | [Data] |
| Empty | [Behavior] | [Behavior] | [Data] |

### Transition Diagram

[Mermaid stateDiagram]

### Edge Cases

| Case | Handling |
|------|----------|
| [Case] | [How to handle] |

### Summary
- States: [N] identified
- Transitions: [N] mapped
- Edge cases: [N] documented

Invocation

Invoke manually with "use state-machine skill" or follow Ask mode CONVERGE loop which references this skill.

Related Skills

• qa-planning - Uses states to define test coverage
• design-context - Check existing component states in Storybook