# Pull Request: Database-Backed Ingredient-Instruction Mapping

## Summary

This PR implements a comprehensive solution for managing ingredient-to-instruction mappings in cooking mode. The feature moves from client-side state management to a persistent database-backed approach, significantly improving reliability and user experience.

## Changes

### Database Schema
- **New Table**: `IngredientInstructionMapping`
  - Many-to-many relationship between ingredients and instructions
  - Includes `order` field for display ordering within instructions
  - Cascade delete for data integrity
  - Migration: `20251031050746_add_ingredient_instruction_mapping`

### Backend (API)

#### New Service
- **`packages/api/src/services/ingredientMatcher.service.ts`**
  - Automatic ingredient matching algorithm
  - Extracts core ingredient names (removes quantities/units)
  - Generates name variations (plural/singular)
  - Finds ingredient positions in instruction text
  - Prevents duplicate mappings (same ingredient appearing multiple times)
  - Cross-step tracking (ingredients only appear once across all steps)

#### API Endpoints
- **Updated GET `/api/recipes/:id`**: Now includes ingredient-instruction mappings in response
- **Updated POST `/api/recipes`**: Automatically generates mappings on recipe creation
- **Updated PUT `/api/recipes/:id`**: Regenerates mappings on recipe update
- **New POST `/api/recipes/:id/ingredient-mappings`**: Manually update mappings
- **New POST `/api/recipes/:id/regenerate-mappings`**: Re-run automatic matching

### Frontend (Web)

#### Simplified Cooking Mode
- **`packages/web/src/pages/CookingMode.tsx`** - Significantly simplified
  - Removed all client-side matching logic (~200 lines removed)
  - Removed localStorage state management
  - Removed drag-and-drop functionality
  - Now purely read-only, displays database-stored mappings
  - Added "⚙️ Manage Ingredients" button for editing

#### New Management Interface
- **`packages/web/src/pages/ManageIngredientMappings.tsx`** - New dedicated page
  - Similar layout to cooking mode for familiarity
  - Drag-and-drop ingredients to instruction steps
  - Remove ingredients with ✕ button
  - Real-time preview of changes
  - Save to database with "💾 Save Changes" button
  - Auto-regenerate with "🔄 Regenerate Auto Mappings" button
  - Navigate to cooking mode with "👨‍🍳 Preview in Cooking Mode" button
  - Unsaved changes warning banner

- **`packages/web/src/styles/ManageIngredientMappings.css`** - Dedicated styling

#### Updated Components
- **`packages/web/src/App.tsx`**: Added route for `/recipes/:id/manage-mappings`
- **`packages/web/src/services/api.ts`**: Added API methods for mapping management
- **`packages/web/src/styles/CookingMode.css`**: Removed unused drag-and-drop styles

### Shared Types
- **`packages/shared/src/types.ts`**
  - Added `IngredientInstructionMapping` interface
  - Updated `Ingredient` and `Instruction` to include optional mapping arrays

### Scripts
- **`packages/api/src/scripts/regenerate-mappings.ts`** - Utility script to regenerate mappings for all existing recipes

## Testing

### Test Results
- ✅ **API Tests**: 24/25 passing (96%)
  - ✅ **New Ingredient Matcher Service**: 11/11 tests passing
  - ✅ **Recipe Routes**: 9/9 tests passing (includes mapping integration)
  - ✅ **Storage Service**: 4/5 passing (1 pre-existing S3 test failure)
- ✅ **Shared Tests**: 16/16 passing (100%)
- ⚠️ **Web Tests**: 7/15 passing (8 pre-existing failures in axios mocking setup)

### New Test Coverage
Created comprehensive unit tests for `ingredientMatcher.service.ts`:
- ✅ Simple ingredient matching
- ✅ Ingredients with quantities in names
- ✅ Plural/singular form matching
- ✅ No duplication across steps
- ✅ No duplication of same core ingredient
- ✅ Recipes with sections
- ✅ Ingredient ordering by text position
- ✅ Error handling for missing recipes
- ✅ Save mappings functionality
- ✅ Auto-map integration

### Manual Testing Performed
- ✅ Created new test recipe with automatic mapping generation
- ✅ Regenerated mappings for 5 existing recipes (Soft Sourdough, Apple Dutch Baby, Ice Cream, etc.)
- ✅ Verified mappings persist across page refreshes
- ✅ Tested drag-and-drop in management interface
- ✅ Tested remove functionality
- ✅ Tested save persistence to database
- ✅ Verified cooking mode displays stored mappings correctly

## Migration Guide

### For Existing Recipes
Run the regeneration script to generate mappings for all existing recipes:
```bash
cd packages/api
npx tsx src/scripts/regenerate-mappings.ts
```

This was already executed and successfully generated mappings for all 5 existing recipes.

### Database Migration
The migration runs automatically when deploying the API container. No manual intervention needed.

## Benefits

1. **Reliability**: Mappings are persisted in database, not client-side localStorage
2. **Consistency**: Same mappings across all clients/devices
3. **Simplicity**: Cooking mode is now read-only with no complex state management
4. **User Control**: Dedicated management interface for editing mappings
5. **Automatic**: Mappings are generated automatically on recipe import/creation
6. **Flexible**: Users can manually adjust mappings if automatic matching is incorrect

## Breaking Changes

None. This is a new feature with backward compatibility. Existing recipes work without mappings, and the system automatically generates them.

## Future Enhancements

- [ ] Add UI to manage mappings during recipe import (for recipes with ambiguous matches)
- [ ] Add reordering of ingredients within instructions (drag-and-drop reorder)
- [ ] Add bulk mapping tools (e.g., "map all ingredients to step 1")
- [ ] Add mapping analytics/suggestions based on common patterns

## Screenshots

### Cooking Mode (Read-Only)
- Clean, distraction-free interface
- Ingredients listed inline with each step
- No edit controls visible

### Manage Ingredient Mappings
- Drag ingredients from top section to instruction steps
- Remove with ✕ button
- Save changes button persists to database
- Regenerate button re-runs automatic matching

## Related Issues

Fixes issues with ingredient mapping:
- Ingredients duplicating when dragging
- Remove button not working
- Changes not persisting across clients
- Complex client-side state management

## Review Checklist

- [x] Database migration created and tested
- [x] API tests updated and passing
- [x] Frontend tests updated (some pre-existing failures remain)
- [x] Manual testing completed
- [x] Documentation updated
- [x] No breaking changes
- [x] Backward compatible