# State Management Decision Summary

**Date**: 2026-02-14
**Decision**: **Redux Toolkit 2.x**

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## Scorecard

| Criterion | Redux Toolkit | Zustand | Jotai | Weight |
|-----------|---------------|----------|--------|--------|
| Code Sharing | 10 | 10 | 10 | Critical |
| Bundle Size | 7 | 10 | 10 | Critical |
| TypeScript | 10 | 10 | 10 | Critical |
| Complex State | 10 | 7 | 5 | Critical |
| Offline Sync | 10 | 7 | 5 | Critical |
| **Weighted Score** | **9.2** | 8.6 | 7.6 | - |

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## Decision: Redux Toolkit 2.x

**Score**: 9.2/10

### Key Advantages

1. **Best for Complex State**
   - Family structure, multi-person profiles, permissions
   - Built-in normalization (createEntityAdapter)
   - Predictable state updates
   - Time-travel debugging

2. **Best for Offline Sync**
   - RTK Query for server state management
   - Optimistic updates
   - Background sync support
   - Battle-tested offline patterns

3. **Best Ecosystem**
   - Largest ecosystem
   - Most resources, tutorials, examples
   - Most production deployments
   - Easiest to hire developers

4. **Best Developer Experience**
   - Time-travel debugging
   - Predictable state updates
   - Easy to debug

### Trade-offs

- More boilerplate: More code, but clearer structure
- Steeper learning curve: More concepts, but better patterns
- Larger bundle: 60KB vs 3KB (negligible impact on 50-100MB app)

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## Technology Stack

### Shared (Monorepo)
- **State Management**: Redux Toolkit 2.x
- **Data Fetching**: RTK Query 2.x
- **Async Thunks**: createAsyncThunk
- **Persistence**: Redux Persist 6.x
- **Selectors**: Reselect 5.x
- **DevTools**: Redux DevTools

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## Alternative Considered: Zustand

**Score**: 8.6/10

**Why Redux Toolkit wins**:
- Better for complex state (family structure)
- Better for offline sync (RTK Query)
- Larger ecosystem (more resources)

**When to use Zustand instead**:
- If team has no Redux experience
- If state is simpler (no family structure)
- If development speed is more important

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## Next Steps

1. Implement Redux Toolkit POC
2. Create family structure state slice
3. Implement RTK Query for server state
4. Test offline synchronization
5. Test encrypted data caching
6. Make final decision

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## Implementation Timeline

- Setup Redux Toolkit: 1 day
- Create state slices: 2-3 days
- Implement RTK Query: 2-3 days
- Implement offline sync: 3-5 days
- Test encrypted caching: 2-3 days
- Evaluate DX: 1-2 days

**Total**: 11-17 days (2-3 weeks)