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What-If Simulator
An interactive scenario planning tool. Adjust income and category-level expenses with sliders to see how changes would affect your runway, tax, cashflow, and spending radar in real time.
What It Shows
| Element | Detail |
|---|---|
| Active/inactive toggle | Simulator must be explicitly activated before changes take effect |
| Preset scenarios | Grid of one-click presets (e.g., "Job loss", "Cut subscriptions") |
| Income slider | Adjusts total income from -100% to +100% |
| Expense sliders | 8 category-specific sliders, each -100% to +100% |
| Impact summary | Monthly Delta (NZD) and Runway Delta (months) |
| Reset All button | Returns all sliders to 0% |
Expense Category Sliders
| Category |
|---|
| Groceries |
| Dining |
| Fuel |
| Transport |
| Utilities |
| Subscriptions |
| Shopping |
| Entertainment |
Each slider ranges from -100% (eliminate entirely) to +100% (double the spending).
Key Features
- Explicit activation -- The simulator does nothing until toggled on. This prevents accidental modification of downstream panels.
- Preset scenarios -- One-click presets that configure multiple sliders at once for common what-if questions.
- Real-time propagation -- Slider changes immediately update all connected panels without requiring a confirm step.
- Impact summary -- Two headline numbers show the combined effect:
- Monthly Delta -- How much more or less you would have per month (NZD).
- Runway Delta -- How many more or fewer months your savings would last.
- Custom-styled range inputs -- Slider tracks use a CSS gradient fill to visually indicate the adjustment direction.
- Color-coded percentages -- Positive adjustments (savings) shown in green, negative (increased spending) in red.
Data Source
| Store / Hook | Fields |
|---|---|
useFinanceStore | simulation (slider values, active state) |
useSimulation | Computed deltas, adjusted runway |
Panels Affected
When the simulator is active, these panels react to the adjusted values:
| Panel | What Changes |
|---|---|
| Runway Panel | Runway months + delta badge |
| Tax Panel | Income tax and GST estimates |
| Cashflow Panel | Forecast periods reflect adjusted income/expenses |
| Radar Panel | Category spending shape changes |
Interactivity
| Action | Result |
|---|---|
| Toggle active | Enables/disables all scenario adjustments |
| Drag income slider | Adjusts income percentage |
| Drag expense slider | Adjusts that category's expense percentage |
| Click preset | Applies a predefined slider configuration |
| Click Reset All | Returns all sliders to 0% |
Related Panels
- Runway Panel -- primary consumer of runway delta
- Cashflow Panel -- forecast reflects adjusted values
- Tax Panel -- tax estimates reflect adjusted income