Three critical lessons:
1. ALWAYS use `ls -la app/filament/Resources/` first to confirm path
2. NEVER use UnitEnum/BackedEnum imports - they are PHP built-in types
3. STOP and thoroughly diagnose when issues repeat, instead of continuing blindly
These are PHP 8.2 built-in enum types, not classes that need importing.
Reference working code:
- SupplierResource.php works WITHOUT these imports
- Use type declarations directly: string|BackedEnum|null and UnitEnum|string|null
Key lessons learned:
1. Directory case sensitivity - app/Filament/ not app/filament/
2. UnitEnum/BackedEnum are PHP 8.2 built-in types, not classes
3. Always verify project structure before making changes
4. Learn from working code instead of assumptions
5. Stop and diagnose thoroughly when issues repeat
Change all Resources' navigationGroup from 'string|UnitEnum|null' to 'UnitEnum|string|null'
Union type order matters: UnitEnum first, then string
All 4 Resources updated:
- CategoryResource
- BrandResource
- PurchaseOrderResource
- StaffScheduleResource
- InventoryTransactionResource
PHP syntax check passed for all files
