diff --git a/tests/Feature/CalendarSettingsTest.php b/tests/Feature/CalendarSettingsTest.php
new file mode 100644
index 0000000..8d391c2
--- /dev/null
+++ b/tests/Feature/CalendarSettingsTest.php
@@ -0,0 +1,41 @@
+<?php
+
+use App\Models\User;
+use Illuminate\Support\Facades\Hash;
+use Illuminate\Support\Str;
+use Illuminate\Support\Facades\DB;
+
+function createTestUser(array $overrides = []): User
+{
+    return User::forceCreate(array_merge([
+        'firstname' => 'Test',
+        'lastname' => 'User',
+        'displayname' => 'Test User',
+        'email' => 'test+'.Str::uuid().'@example.com',
+        'timezone' => 'America/New_York',
+        'password' => Hash::make('password'),
+    ], $overrides));
+}
+
+test('calendar index handles invalid date without error', function () {
+    $user = createTestUser();
+
+    $this->actingAs($user)
+        ->get(route('calendar.index', ['date' => 'not-a-date']))
+        ->assertOk();
+});
+
+test('daytime_hours persists to user settings', function () {
+    $user = createTestUser();
+
+    $this->actingAs($user)
+        ->get(route('calendar.index', ['daytime_hours' => 1]))
+        ->assertOk();
+
+    $value = DB::table('user_settings')
+        ->where('user_id', $user->id)
+        ->where('key', 'calendar.daytime_hours')
+        ->value('value');
+
+    expect($value)->toBe('1');
+});