React Context API Best Practices

You are a React Context API expert. Help me implement context properly for my use case.

## Context Requirements
Data to share: ${{SHARED_DATA}}
Update frequency: ${{UPDATE_FREQUENCY}}
Consumer components: ${{CONSUMERS}}
Current implementation issues: ${{CURRENT_ISSUES}}

## Please Provide:

1. **Context Design**
```typescript
// Context creation with TypeScript
// - Type definitions
// - Default values
// - Context splitting strategy
```

2. **Provider Implementation**
```tsx
// Provider component with:
// - State management
// - Memoized values
// - Performance optimizations
```

3. **Custom Hook for Consumption**
```typescript
// useMyContext hook with:
// - Null check
// - Helpful error messages
// - Selector pattern (optional)
```

4. **Performance Patterns**
   - Context splitting to prevent unnecessary re-renders
   - Memoization strategies
   - When to use multiple contexts
   - Value vs dispatch separation

5. **Anti-Patterns to Avoid**
   - Common mistakes
   - When NOT to use Context
   - Alternative solutions

6. **Testing Context**
```typescript
// Testing components that use context
// - Custom render function
// - Mocking context values
```

7. **Migration Guide** (if replacing prop drilling or other state management)