diff --git a/.env.testing b/.env.testing
new file mode 100644
index 0000000..d154f99
--- /dev/null
+++ b/.env.testing
@@ -0,0 +1,14 @@
+APP_ENV=testing
+APP_KEY=base64:Ftjcs9gvv7IgMLvSzaCQIaqIPBFO2fezCFUb+owUSCE=
+DB_CONNECTION=mysql
+DB_DATABASE=d2dTest
+
+SZUNETNAPOK_API_KEY=test_api_key
+SZUNETNAPOK_API_URL=https://szunetnapok.hu/api/
+DB_HOST=127.0.0.1
+DB_PORT=3306
+DB_USERNAME=root
+DB_PASSWORD=
+CACHE_DRIVER=array
+SESSION_DRIVER=array
+QUEUE_CONNECTION=sync
diff --git a/app/Console/Commands/CheckTestDb.php b/app/Console/Commands/CheckTestDb.php
new file mode 100644
index 0000000..3be27f6
--- /dev/null
+++ b/app/Console/Commands/CheckTestDb.php
@@ -0,0 +1,58 @@
+<?php
+
+namespace App\Console\Commands;
+
+use Illuminate\Console\Command;
+use Illuminate\Support\Facades\DB;
+
+class CheckTestDb extends Command
+{
+    /**
+     * The name and signature of the console command.
+     *
+     * @var string
+     */
+    protected $signature = 'app:check-test-db';
+
+    /**
+     * The console command description.
+     *
+     * @var string
+     */
+    protected $description = 'Ellenőrzi a pillanatnyi adatbázis kapcsolatot és az aktív environmentet.';
+
+    /**
+     * Execute the console command.
+     */
+    public function handle()
+    {
+        $this->newLine();
+        $this->info('--- Adatbázis Kapcsolat Ellenőrzése ---');
+        $this->info('APP_ENV: ' . app()->environment());
+        $this->info('DB_CONNECTION: ' . config('database.default'));
+        $this->info('DB_DATABASE (config): ' . config('database.connections.mysql.database'));
+        $this->info('DB_DATABASE (env): ' . env('DB_DATABASE'));
+
+        try {
+            $dbName = DB::select('SELECT DATABASE() as db')[0]->db;
+            $this->info('TÉNYLEGES ADATBÁZIS (MySQL select): ' . $dbName);
+
+            if (app()->environment() === 'testing' && strtolower($dbName) !== strtolower('d2dTest')) {
+                $this->error('VIGYÁZAT: Teszt környezetben nem a d2dTest adatbázist használod! (Kapcsolódva: ' . $dbName . ')');
+            } elseif (app()->environment() === 'testing' && strtolower($dbName) === strtolower('d2dTest')) {
+                $this->success('Minden rendben: Teszt környezetben a d2dTest adatbázist használod.');
+            }
+        } catch (\Exception $e) {
+            $this->error('Hiba az adatbázishoz való csatlakozáskor: ' . $e->getMessage());
+        }
+        $this->newLine();
+    }
+
+    /**
+     * Success message override
+     */
+    protected function success(string $message)
+    {
+        $this->line("<info>{$message}</info>");
+    }
+}
diff --git a/app/Console/Commands/SyncWorkCalendar.php b/app/Console/Commands/SyncWorkCalendar.php
new file mode 100644
index 0000000..99e2cef
--- /dev/null
+++ b/app/Console/Commands/SyncWorkCalendar.php
@@ -0,0 +1,44 @@
+<?php
+
+namespace App\Console\Commands;
+
+use Illuminate\Console\Command;
+
+class SyncWorkCalendar extends Command
+{
+    /**
+     * The name and signature of the console command.
+     *
+     * @var string
+     */
+    protected $signature = 'app:sync-work-calendar {year? : A szinkronizálandó év (alapértelmezett: aktuális)}';
+
+    /**
+     * The console command description.
+     *
+     * @var string
+     */
+    protected $description = 'Munkaszüneti napok szinkronizálása külső API-ból';
+
+    /**
+     * Execute the console command.
+     */
+    public function handle(\App\Services\WorkCalendarService $service): int
+    {
+        $year = $this->argument('year') ? (int) $this->argument('year') : now()->year;
+
+        $this->info("Szinkronizálás indítása {$year} évre...");
+
+        if ($service->syncFromApi($year)) {
+            $this->info('A szinkronizálás sikeresen befejeződött.');
+            return self::SUCCESS;
+        }
+
+        $this->error('A szinkronizálás során hiba történt:');
+        foreach ($service->getError() as $error) {
+            $this->error("- " . implode(', ', (array) $error));
+        }
+
+        return self::FAILURE;
+    }
+}
diff --git a/app/Console/Kernel.php b/app/Console/Kernel.php
index e6b9960..627d3e6 100644
--- a/app/Console/Kernel.php
+++ b/app/Console/Kernel.php
@@ -13,6 +13,7 @@ class Kernel extends ConsoleKernel
     protected function schedule(Schedule $schedule): void
     {
         // $schedule->command('inspire')->hourly();
+       // $schedule->command('app:sync-work-calendar')->quarterly();
     }
 
     /**
diff --git a/app/Enums/DataSource.php b/app/Enums/DataSource.php
new file mode 100644
index 0000000..d26d892
--- /dev/null
+++ b/app/Enums/DataSource.php
@@ -0,0 +1,17 @@
+<?php
+
+namespace App\Enums;
+
+enum DataSource: string
+{
+    case Api = 'api';
+    case Manual = 'manual';
+
+    public function label(): string
+    {
+        return match($this) {
+            self::Api => 'API',
+            self::Manual => 'Kézi rögzítés',
+        };
+    }
+}
diff --git a/app/Enums/WorkDayType.php b/app/Enums/WorkDayType.php
new file mode 100644
index 0000000..72f9c53
--- /dev/null
+++ b/app/Enums/WorkDayType.php
@@ -0,0 +1,25 @@
+<?php
+
+namespace App\Enums;
+
+enum WorkDayType: string
+{
+    case Holiday = 'holiday';       // Munkaszüneti nap
+    case WorkingDay = 'working_day'; // Plusz munkanap (pl. szombat)
+
+    public function label(): string
+    {
+        return match($this) {
+            self::Holiday => 'Munkaszüneti nap',
+            self::WorkingDay => 'Áthelyezett munkanap',
+        };
+    }
+
+    public function color(): string
+    {
+        return match($this) {
+            self::Holiday => 'danger',
+            self::WorkingDay => 'success',
+        };
+    }
+}
diff --git a/app/Models/WorkCalendar.php b/app/Models/WorkCalendar.php
new file mode 100644
index 0000000..8d8a3ad
--- /dev/null
+++ b/app/Models/WorkCalendar.php
@@ -0,0 +1,34 @@
+<?php
+
+namespace App\Models;
+
+use App\Enums\DataSource;
+use App\Enums\WorkDayType;
+use Illuminate\Database\Eloquent\SoftDeletes;
+
+class WorkCalendar extends BaseAuditable
+{
+    use SoftDeletes;
+
+    protected $casts = [
+        'date' => 'date',
+        'type' => WorkDayType::class,
+        'data_source' => DataSource::class,
+    ];
+
+    /**
+     * Meghatározza, hogy az adott nap munkaszüneti nap-e az adatbázis szerint.
+     */
+    public function isHoliday(): bool
+    {
+        return $this->type === WorkDayType::Holiday;
+    }
+
+    /**
+     * Meghatározza, hogy az adott nap plusz munkanap-e az adatbázis szerint.
+     */
+    public function isWorkingDay(): bool
+    {
+        return $this->type === WorkDayType::WorkingDay;
+    }
+}
diff --git a/app/Services/WorkCalendarService.php b/app/Services/WorkCalendarService.php
new file mode 100644
index 0000000..1abc7e9
--- /dev/null
+++ b/app/Services/WorkCalendarService.php
@@ -0,0 +1,136 @@
+<?php
+
+namespace App\Services;
+
+use App\Enums\DataSource;
+use App\Enums\WorkDayType;
+use App\Models\WorkCalendar;
+use Illuminate\Support\Carbon;
+use Illuminate\Support\Collection;
+use Illuminate\Support\Facades\Http;
+use Illuminate\Support\Facades\Log;
+
+class WorkCalendarService extends ServiceBase
+{
+    /**
+     * Szinkronizálja a munkaszüneti napokat a szunetnapok.hu API-ból.
+     */
+    public function syncFromApi(?int $year = null): bool
+    {
+        $year ??= now()->year;
+        $config = config('services.szunetnapok');
+        $apiKey = $config['key'] ?? null;
+        $apiUrl = rtrim($config['url'] ?? 'https://szunetnapok.hu/api/', '/');
+        $verify = $config['verify'] ?? true;
+
+        Log::channel('work_calendar')->info('WorkCalendar sync started.', [
+            'year' => $year,
+            'api_url' => $apiUrl,
+            'has_api_key' => !empty($apiKey),
+            'ssl_verify' => $verify,
+        ]);
+
+        if (empty($apiKey)) {
+            $this->error->add('api', 'Hiányzó szunetnapok.hu API kulcs.');
+            Log::channel('work_calendar')->error('WorkCalendar sync failed: Missing API key.');
+            return false;
+        }
+
+        try {
+            $response = Http::withOptions(['verify' => $verify])
+                ->get("{$apiUrl}/{$apiKey}/{$year}/json");
+
+            Log::channel('work_calendar')->info('WorkCalendar API response.', [
+                'status' => $response->status(),
+                'body' => $response->body(),
+            ]);
+
+            if ($response->failed()) {
+                $this->error->add('api', 'Nem sikerült elérni a szunetnapok.hu API-t.');
+                return false;
+            }
+        } catch (\Exception $e) {
+            $this->error->add('api', 'Hálózati hiba az API hívás közben: ' . $e->getMessage());
+            Log::channel('work_calendar')->error('WorkCalendar sync API error (cURL/SSL):', [
+                'message' => $e->getMessage(),
+                'exception' => get_class($e),
+            ]);
+            return false;
+        }
+
+        $data = $response->json();
+
+        if (($data['response'] ?? '') !== 'OK') {
+            $this->error->add('api', $data['message'] ?? 'Hibás válasz az API-tól.');
+            return false;
+        }
+
+        if (!isset($data['days']) || !is_array($data['days'])) {
+            Log::channel('work_calendar')->info('WorkCalendar sync: No days to process.');
+            return true;
+        }
+
+        $savedRecords = [];
+
+        foreach ($data['days'] as $day) {
+            $type = ($day['type'] == 1) ? WorkDayType::Holiday : WorkDayType::WorkingDay;
+
+            $record = WorkCalendar::updateOrCreate(
+                ['date' => $day['date']],
+                [
+                    'type' => $type,
+                    'description' => $day['name'] ?? '',
+                    'data_source' => DataSource::Api,
+                ]
+            );
+
+            $savedRecords[] = $record->toArray();
+        }
+
+        Log::channel('work_calendar')->info('WorkCalendar sync completed.', [
+            'count' => count($savedRecords),
+            'records' => $savedRecords,
+        ]);
+
+        return true;
+    }
+
+    /**
+     * Megállapítja, hogy az adott nap munkanap-e.
+     */
+    public function isWorkDay(Carbon $date): bool
+    {
+        $record = WorkCalendar::where('date', $date->toDateString())->first();
+
+        if ($record) {
+            return $record->type === WorkDayType::WorkingDay;
+        }
+
+        // Ha nincs az adatbázisban, a hétvégék alapján döntünk
+        return !$date->isWeekend();
+    }
+
+    /**
+     * Kiszámítja a következő érvényes munkanapot.
+     */
+    public function getNextWorkDay(Carbon $date): Carbon
+    {
+        $nextDay = $date->copy()->addDay();
+
+        while (!$this->isWorkDay($nextDay)) {
+            $nextDay->addDay();
+        }
+
+        return $nextDay;
+    }
+
+    /**
+     * Visszaadja a megadott időszak munkaszüneti napjait és plusz munkanapjait.
+     */
+    public function getCalendarEntries(Carbon $start, Carbon $end): Collection
+    {
+        return WorkCalendar::whereBetween('date', [$start->toDateString(), $end->toDateString()])
+            ->orderBy('date')
+            ->get();
+    }
+}
diff --git a/config/logging.php b/config/logging.php
index c473c48..574f1d1 100644
--- a/config/logging.php
+++ b/config/logging.php
@@ -81,6 +81,13 @@
             // 'formatter'=>\Monolog\Formatter\HtmlFormatter::class,
         ],
 
+        'work_calendar' => [
+            'driver' => 'daily',
+            'path' => storage_path('logs/WorkCalendarAPI.log'),
+            'level' => env('LOG_LEVEL', 'debug'),
+            'days' => 14,
+        ],
+
         'BrowserConsole' => [
             'driver' => 'monolog',
             'handler' => \Monolog\Handler\BrowserConsoleHandler::class,
diff --git a/config/services.php b/config/services.php
index 6a90eb8..9b85fa7 100644
--- a/config/services.php
+++ b/config/services.php
@@ -35,4 +35,10 @@
         ],
     ],
 
+    'szunetnapok' => [
+        'key' => env('SZUNETNAPOK_API_KEY'),
+        'url' => env('SZUNETNAPOK_API_URL', 'https://szunetnapok.hu/api/'),
+        'verify' => env('SZUNETNAPOK_API_VERIFY', true),
+    ],
+
 ];
diff --git a/database/migrations/2026_04_08_184130_create_work_calendars_table.php b/database/migrations/2026_04_08_184130_create_work_calendars_table.php
new file mode 100644
index 0000000..9235bbe
--- /dev/null
+++ b/database/migrations/2026_04_08_184130_create_work_calendars_table.php
@@ -0,0 +1,39 @@
+<?php
+
+use Illuminate\Database\Migrations\Migration;
+use Illuminate\Database\Schema\Blueprint;
+use Illuminate\Support\Facades\Schema;
+
+return new class extends Migration
+{
+    /**
+     * Run the migrations.
+     */
+    public function up(): void
+    {
+        Schema::create('work_calendars', function (Blueprint $table) {
+            $table->id();
+            $table->date('date')->unique();
+            $table->enum('type', array_column(\App\Enums\WorkDayType::cases(), 'value'));
+            $table->enum('data_source', array_column(\App\Enums\DataSource::cases(), 'value'))->default(\App\Enums\DataSource::Manual->value);
+            $table->text('description')->nullable();
+
+            // Audit mezők a BaseAuditable-hoz
+            $table->unsignedBigInteger('created_by')->nullable();
+            $table->unsignedBigInteger('updated_by')->nullable();
+            $table->unsignedBigInteger('deleted_by')->nullable();
+            $table->timestamps();
+            $table->softDeletes();
+
+            $table->index('date');
+        });
+    }
+
+    /**
+     * Reverse the migrations.
+     */
+    public function down(): void
+    {
+        Schema::dropIfExists('work_calendars');
+    }
+};
diff --git a/phpunit.xml b/phpunit.xml
index d703241..461fb27 100644
--- a/phpunit.xml
+++ b/phpunit.xml
@@ -23,8 +23,8 @@
         <env name="BCRYPT_ROUNDS" value="4"/>
         <env name="BROADCAST_CONNECTION" value="null"/>
         <env name="CACHE_STORE" value="array"/>
-        <env name="DB_CONNECTION" value="sqlite"/>
-        <env name="DB_DATABASE" value=":memory:"/>
+        <env name="DB_CONNECTION" value="mysql"/>
+        <env name="DB_DATABASE" value="d2dTest"/>
         <env name="MAIL_MAILER" value="array"/>
         <env name="QUEUE_CONNECTION" value="sync"/>
         <env name="SESSION_DRIVER" value="array"/>
diff --git a/tests/Feature/WorkCalendarServiceTest.php b/tests/Feature/WorkCalendarServiceTest.php
new file mode 100644
index 0000000..e565a70
--- /dev/null
+++ b/tests/Feature/WorkCalendarServiceTest.php
@@ -0,0 +1,173 @@
+<?php
+
+use App\Enums\WorkDayType;
+use App\Models\WorkCalendar;
+use App\Services\WorkCalendarService;
+use Tests\TestCase;
+use Illuminate\Foundation\Testing\RefreshDatabase;
+use Illuminate\Support\Carbon;
+use Illuminate\Support\Facades\Log;
+
+uses(TestCase::class, RefreshDatabase::class);
+
+test('it correctly identifies working days and holidays', function () {
+    $service = new WorkCalendarService();
+
+    // 2026-04-11 Szombat (Alapesetben nem munkanap)
+    $saturday = Carbon::parse('2026-04-11');
+    expect($service->isWorkDay($saturday))->toBeFalse();
+
+    // 2026-04-13 Hétfő (Alapesetben munkanap)
+    $monday = Carbon::parse('2026-04-13');
+    expect($service->isWorkDay($monday))->toBeTrue();
+
+    // Rögzítsünk egy szünnapot a hétfőre
+    WorkCalendar::create([
+        'date' => '2026-04-13',
+        'type' => WorkDayType::Holiday,
+        'description' => 'Test Holiday'
+    ]);
+
+    expect($service->isWorkDay($monday))->toBeFalse();
+
+    // Rögzítsünk egy munkanapot a szombatra
+    WorkCalendar::create([
+        'date' => '2026-04-11',
+        'type' => WorkDayType::WorkingDay,
+        'description' => 'Test Working Saturday'
+    ]);
+
+    expect($service->isWorkDay($saturday))->toBeTrue();
+});
+
+test('it calculates next working day correctly', function () {
+    $service = new WorkCalendarService();
+
+    // 2026-04-10 Péntek
+    $friday = Carbon::parse('2026-04-10');
+
+    // Alapesetben a hétvége miatt hétfő lesz a következő munkanap
+    expect($service->getNextWorkDay($friday)->toDateString())->toBe('2026-04-13');
+
+    // Ha a szombat munkanap lesz
+    WorkCalendar::create([
+        'date' => '2026-04-11',
+        'type' => WorkDayType::WorkingDay,
+        'description' => 'Working Saturday'
+    ]);
+
+    expect($service->getNextWorkDay($friday)->toDateString())->toBe('2026-04-11');
+
+    // Ha a hétfő szünnap lesz
+    WorkCalendar::create([
+        'date' => '2026-04-13',
+        'type' => WorkDayType::Holiday,
+        'description' => 'Monday Holiday'
+    ]);
+
+    // Péntek után szombat munkanap, vasárnap nem, hétfő szünnap -> kedd (04-14)
+    expect($service->getNextWorkDay($friday)->toDateString())->toBe('2026-04-11');
+
+    $saturday = Carbon::parse('2026-04-11');
+    expect($service->getNextWorkDay($saturday)->toDateString())->toBe('2026-04-14');
+});
+
+test('it can sync holidays from API', function () {
+    $service = new WorkCalendarService();
+
+    Http::fake([
+        'szunetnapok.hu/api/*' => Http::response([
+            'response' => 'OK',
+            'year' => 2026,
+            'days' => [
+                [
+                    'date' => '2026-01-01',
+                    'name' => 'Új Év napja',
+                    'type' => 1,
+                    'weekday' => 5
+                ],
+                [
+                    'date' => '2026-05-10',
+                    'name' => 'Áthelyezett munkanap',
+                    'type' => 2,
+                    'weekday' => 6
+                ]
+            ]
+        ], 200)
+    ]);
+
+    $result = $service->syncFromApi(2026);
+
+    expect($result)->toBeTrue();
+    expect(WorkCalendar::count())->toBe(2);
+
+    $holiday = WorkCalendar::where('date', '2026-01-01')->first();
+    expect($holiday->type)->toBe(WorkDayType::Holiday);
+    expect($holiday->data_source)->toBe(\App\Enums\DataSource::Api);
+
+    $workingDay = WorkCalendar::where('date', '2026-05-10')->first();
+    expect($workingDay->type)->toBe(WorkDayType::WorkingDay);
+    expect($workingDay->data_source)->toBe(\App\Enums\DataSource::Api);
+});
+
+test('it handles API errors during sync', function () {
+    $service = new WorkCalendarService();
+
+    Http::fake([
+        'szunetnapok.hu/api/*' => Http::response([
+            'response' => 'Error',
+            'message' => 'Nincs API kulcs megadva'
+        ], 200)
+    ]);
+
+    $result = $service->syncFromApi(2026);
+
+    expect($result)->toBeFalse();
+    expect($service->getError()['api'][0])->toBe('Nincs API kulcs megadva');
+});
+
+test('it logs API calls and database entries during sync', function () {
+    $service = new WorkCalendarService();
+
+    Http::fake([
+        'szunetnapok.hu/api/*' => Http::response([
+            'response' => 'OK',
+            'days' => [
+                [
+                    'date' => '2026-01-01',
+                    'name' => 'Új Év',
+                    'type' => 1
+                ]
+            ]
+        ], 200)
+    ]);
+
+    $mock = Log::partialMock();
+    $mock->shouldReceive('channel')->with('work_calendar')->andReturnSelf();
+    $mock->shouldReceive('info')->atLeast()->once();
+
+    $service->syncFromApi(2026);
+});
+
+test('it logs cURL/SSL exceptions during sync', function () {
+    $service = new WorkCalendarService();
+
+    Http::fake([
+        'szunetnapok.hu/api/*' => function () {
+            throw new \Exception('cURL error 60: SSL certificate problem');
+        }
+    ]);
+
+    $mock = Log::partialMock();
+    $mock->shouldReceive('channel')->with('work_calendar')->andReturnSelf();
+    $mock->shouldReceive('info')->once(); // Start log
+    $mock->shouldReceive('error')->once()->withArgs(function ($message, $context) {
+        return str_contains($message, 'cURL/SSL') &&
+               str_contains($context['message'], 'SSL certificate problem');
+    });
+
+    $result = $service->syncFromApi(2026);
+
+    expect($result)->toBeFalse();
+    expect($service->getError()['api'][0])->toContain('Hálózati hiba');
+});
diff --git a/tests/TestCase.php b/tests/TestCase.php
index fe1ffc2..89b2649 100644
--- a/tests/TestCase.php
+++ b/tests/TestCase.php
@@ -6,5 +6,14 @@
 
 abstract class TestCase extends BaseTestCase
 {
-    //
+    protected function setUp(): void
+    {
+        parent::setUp();
+
+        $currentDb = config('database.connections.mysql.database');
+
+        if (strtolower($currentDb) !== strtolower('d2dTest') && env('APP_ENV') === 'testing') {
+            throw new \Exception('KRITIKUS HIBA: A tesztek NEM a d2dTest adatbázison futnak! Aktuális adatbázis: ' . $currentDb);
+        }
+    }
 }