# StateNormalization Utility Audit

**Date**: 2025-01-27  
**Action**: 4.6.1.11  
**Status**: ✅ Complete

## Summary

The `stateNormalization` utility (`apps/web/src/utils/stateNormalization.ts`) is **only used in an outdated test file** that tests obsolete Library Store functionality. The Library Store no longer uses normalized state structure (migrated to React Query in Action 4.1.2.6).

## Usage Analysis

### Imports
- ✅ **One import found**: `apps/web/src/test/stores.test.ts` (line 7)
  - Imports `createEmptyNormalized` function
  - Used in tests for Library Store (lines 158-159)
  - Tests are **outdated** - they test `state.items` and `state.favorites` which no longer exist

### Functions Exported
1. `normalize<T>()` - Normalize array to normalized state
2. `denormalize<T>()` - Convert normalized state back to array
3. `addToNormalized<T>()` - Add item to normalized state
4. `updateInNormalized<T>()` - Update item in normalized state
5. `removeFromNormalized<T>()` - Remove item from normalized state
6. `replaceNormalized<T>()` - Replace all items
7. `mergeNormalized<T>()` - Merge items into normalized state
8. `getById<T>()` - Get item by ID
9. `getByIds<T>()` - Get multiple items by IDs
10. `hasId<T>()` - Check if item exists
11. `getCount<T>()` - Get count of items
12. `createEmptyNormalized<T>()` - Create empty normalized state
13. `reorderNormalized<T>()` - Reorder items

**Only `createEmptyNormalized` is used, and only in outdated tests.**

### Other "normalize" Matches
The grep found many other "normalize" functions, but they are **different utilities**:
- `normalizeId()` / `normalizeObjectIds()` - ID normalization (different utility, still used)
- `normalizeUrl()` - URL normalization (different utility, still used)
- `normalizeDate()` - Date normalization (different utility, still used)
- `normalizeError()` - Error normalization (different utility, still used)
- `normalizeEndpoint()` - API endpoint normalization (different utility, still used)

These are **not related** to `stateNormalization.ts`.

## Historical Context

- Previously used by Library Store to normalize `items` and `favorites` arrays into `{ byId, allIds }` structure
- Removed in Action 4.1.2.6 when Library Store domain data was migrated to React Query
- React Query handles data fetching and caching, making normalization unnecessary

## Current State

The Library Store now only contains UI state (filters):
```typescript
export interface LibraryState {
  filters: {
    type?: string;
    search?: string;
  };
}
```

Domain data (items, favorites) is managed by React Query hooks.

## Recommendation

✅ **Safe to remove** - The utility is only used in outdated tests. However:
1. **Option A (Recommended)**: Update `apps/web/src/test/stores.test.ts` to remove outdated Library Store tests, then delete the utility
2. **Option B**: Delete the utility and fix the test file (it will fail, but tests are already outdated)

## Next Steps

- **Action 4.6.1.12**: Remove stateNormalization if unused ✅ (confirmed unused, but test file needs update)
