Composer maps App\ to src/. Find the namespace and case mismatches that can break PSR-4 loading.
php
<?php
// File: src/Service/TaxCalculator.php
namespace App\Services;
final class TaxCalculator {}
namespace App\Checkout;
use app\Services\TaxCalculator;
final class Checkout
{
public function tax(): TaxCalculator
{
return new TaxCalculator();
}
}