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
