# Quickstart: Combat Conditions

## Prerequisites

```bash
pnpm install          # install dependencies (no new packages needed)
pnpm --filter web dev # start dev server at localhost:5173
```

## Implementation Order

1. **Domain: Condition types & registry** (`packages/domain/src/conditions.ts`)
   - Define `ConditionId` union type and `ConditionDefinition` interface
   - Create `CONDITION_DEFINITIONS` static array with all 15 entries
   - Export `VALID_CONDITION_IDS` set for validation

2. **Domain: Extend Combatant** (`packages/domain/src/types.ts`)
   - Add `readonly conditions?: readonly ConditionId[]` to `Combatant`

3. **Domain: Events** (`packages/domain/src/events.ts`)
   - Add `ConditionAdded` and `ConditionRemoved` event types
   - Add to `DomainEvent` union

4. **Domain: Operations** (`packages/domain/src/toggle-condition.ts`)
   - `toggleCondition(encounter, combatantId, conditionId)` — add if absent, remove if present
   - Maintains sorted order and emits `ConditionAdded` or `ConditionRemoved` event

5. **Domain: Tests** (`packages/domain/src/__tests__/`)
   - Test toggle on/off, ordering, duplicate prevention, unknown condition rejection, immutability

6. **Application: Use case** (`packages/application/src/`)
   - `toggleConditionUseCase` following `setAcUseCase` pattern

7. **Web: Persistence** (`apps/web/src/persistence/encounter-storage.ts`)
   - Add conditions rehydration with validation against `VALID_CONDITION_IDS`

8. **Web: Components** (`apps/web/src/components/`)
   - `condition-tags.tsx` — renders icon tags + "+" button
   - `condition-picker.tsx` — popover with all 15 conditions for toggling
   - Update `combatant-row.tsx` to include condition area below name

9. **Web: Hook** (`apps/web/src/hooks/use-encounter.ts`)
   - Add `toggleCondition` callback

## Verification

```bash
pnpm check   # must pass: knip + format + lint + typecheck + test
```

## Key Patterns to Follow

- **Domain operations**: See `packages/domain/src/set-ac.ts` for the exact pattern
- **Use cases**: See `packages/application/src/set-ac-use-case.ts`
- **UI components**: See `combatant-row.tsx` AcInput for inline editing pattern
- **Persistence**: See `encounter-storage.ts` AC validation for rehydration pattern
- **Hook integration**: See `use-encounter.ts` setAc callback for wiring pattern