Implement the 017-combat-conditions feature that adds D&D 5e status conditions to combatants with icon tags, color coding, and a compact toggle picker in the encounter tracker

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

specs/017-combat-conditions/quickstart.md

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+# 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