Refactor model imports and update admin classes to use pghistory for historical tracking; replace HistoricalModel with TrackedModel in relevant models

memory-bank/decisions/history-tracking-migration.md

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+# History Tracking Migration
+
+## Context
+The project is transitioning from django-simple-history to django-pghistory for model history tracking.
+
+## Implementation Details
+
+### Base Implementation (history_tracking/models.py)
+- Both old and new implementations maintained during transition:
+  - `HistoricalModel` - Legacy base class using django-simple-history
+  - `TrackedModel` - New base class using django-pghistory
+- Custom `DiffMixin` for comparing historical records
+- Maintained `HistoricalSlug` for backward compatibility
+
+### Transition Strategy
+1. Maintain Backward Compatibility
+   - Keep both HistoricalModel and TrackedModel during transition
+   - Update models one at a time to use TrackedModel
+   - Ensure no breaking changes during migration
+
+2. Model Updates
+   - Designer (Completed)
+     - Migrated to TrackedModel
+     - Updated get_by_slug to use pghistory queries
+     - Removed SimpleHistoryAdmin dependency
+   
+   - Pending Model Updates
+     - Companies (Company, Manufacturer)
+     - Parks (Park, ParkArea)
+     - Rides (Ride, RollerCoasterStats)
+     - Location models
+
+### Migration Process
+1. For Each Model:
+   - Switch base class from HistoricalModel to TrackedModel
+   - Update admin.py to remove SimpleHistoryAdmin
+   - Create and apply migrations
+   - Test history tracking functionality
+   - Update any history-related queries
+
+2. Testing Steps
+   - Create test objects
+   - Make changes
+   - Verify history records
+   - Check diff functionality
+   - Validate historical slug lookup
+
+3. Admin Integration
+   - Remove SimpleHistoryAdmin
+   - Use standard ModelAdmin
+   - Keep existing list displays and search fields
+
+## Benefits
+- Native PostgreSQL trigger-based tracking
+- More efficient storage and querying
+- Better performance characteristics
+- Context tracking capabilities
+
+## Rollback Plan
+Since both implementations are maintained:
+1. Revert model inheritance to HistoricalModel
+2. Restore SimpleHistoryAdmin
+3. Keep existing migrations
+
+## Next Steps
+1. Create migrations for Designer model
+2. Update remaining models in this order:
+   a. Companies app
+   b. Parks app
+   c. Rides app
+   d. Location app
+3. Test historical functionality
+4. Once all models are migrated:
+   - Remove HistoricalModel class
+   - Remove django-simple-history dependency
+   - Update documentation
+
+## Technical Notes
+- Uses pghistory's default tracking configuration
+- Maintains compatibility with existing code patterns
+- Custom diff functionality preserved
+- Historical slug tracking unchanged
+- Both tracking systems can coexist during migration
+
+## Completion Criteria
+1. All models migrated to TrackedModel
+2. All functionality tested and working
+3. No dependencies on django-simple-history
+4. Documentation updated to reflect new implementation
+5. All migrations applied successfully