incr/app/Http/Controllers/CounterController.php

<?php

declare(strict_types=1);

namespace App\Http\Controllers;

use App\Models\Tracker;
use Illuminate\Http\JsonResponse;
use Illuminate\Http\Request;

class CounterController extends Controller
{
    public function increment(): JsonResponse
    {
        $tracker = Tracker::current();

        if (! $tracker) {
            return response()->json(['error' => 'No counter found.'], 404);
        }

        $tracker->increment('count');
        $tracker->refresh();

        return response()->json(['count' => $tracker->count]);
    }

    public function update(Request $request): JsonResponse
    {
        $validated = $request->validate([
            'count' => 'required|integer|min:0|max:4294967295',
        ]);

        $tracker = Tracker::current();

        if (! $tracker) {
            return response()->json(['error' => 'No counter found.'], 404);
        }

        $tracker->update(['count' => $validated['count']]);

        return response()->json(['count' => $tracker->count]);
    }
}