fix: stop counting held seats in edit usage

src/Service/ServiceAvailabilityCalculator.php

@@ -219,6 +219,10 @@ class ServiceAvailabilityCalculator
     /**
      * Calculate how many times each service has been selected by other participants.
      *
+     * Only new selections count. In edit mode the form is prefilled with the live booking, whose
+     * seats BusPro has already deducted from frei; counting them again would report a contingent
+     * as exhausted while seats are still free.
+     *
      * @param BookingDto $bookingDto              The booking data with participant selections
      * @param int        $currentParticipantIndex The index of the participant currently filling the form
      *
@@ -238,6 +242,10 @@ class ServiceAvailabilityCalculator
             $participantUsage = $this->countParticipantServiceUsage($participant);
 
             foreach ($participantUsage as $serviceId => $count) {
+                if (null !== $bookingDto->booking && $bookingDto->booking->hasServiceForParticipant($index, $serviceId)) {
+                    --$count;
+                }
+
                 $serviceUsage[$serviceId] = ($serviceUsage[$serviceId] ?? 0) + $count;
             }
         }

tests/Service/ServiceAvailabilityCalculatorTest.php

@@ -112,6 +112,30 @@ class ServiceAvailabilityCalculatorTest extends TestCase
         $this->assertFalse($this->calculator->isServiceUnavailable(1, $bookingDto, 0));
     }
 
+    public function testSeatsHeldByOtherParticipantsDoNotCountTowardUsageInEditMode(): void
+    {
+        // BusPro reports frei="3" after deducting the seats this booking already holds
+        $parkingService = $this->createParkingService(id: 1, available: 3);
+        $bookingDto = $this->createEditBookingDtoWithServices([$parkingService]);
+        $this->holdParkingForOtherParticipants($bookingDto, $parkingService, [1, 2, 3, 4, 5, 6, 7, 8]);
+
+        $this->assertFalse($this->calculator->isServiceUnavailable(1, $bookingDto, 0));
+        $this->assertSame(3, $this->calculator->calculateRemainingAvailability($bookingDto, 0)[1]);
+    }
+
+    public function testNewSelectionByOtherParticipantStillCountsTowardUsageInEditMode(): void
+    {
+        $parkingService = $this->createParkingService(id: 1, available: 1);
+        $bookingDto = $this->createEditBookingDtoWithServices([$parkingService]);
+
+        $otherParticipant = new ParticipantDto();
+        $otherParticipant->parkingService = $parkingService;
+        $bookingDto->participants[1] = $otherParticipant;
+
+        // Participant 1 picks the last slot in this edit without holding it in the booking
+        $this->assertTrue($this->calculator->isServiceUnavailable(1, $bookingDto, 0));
+    }
+
     public function testAutoBookedOnRequestServiceStaysAvailableInEditMode(): void
     {
         $service = $this->createSkiPass(id: 1, available: 10, status: Constants::STATUS_ON_REQUEST);
@@ -236,4 +260,23 @@ class ServiceAvailabilityCalculatorTest extends TestCase
 
         return $bookingDto;
     }
+
+    /**
+     * Prefills the given participants with the parking service, as the edit form does for a
+     * service they hold in the live booking.
+     *
+     * @param list<int> $participantIndexes
+     */
+    private function holdParkingForOtherParticipants(BookingDto $bookingDto, Service $parkingService, array $participantIndexes): void
+    {
+        $held = clone $parkingService;
+        $held->mapping = $participantIndexes;
+        $bookingDto->booking->additionalServices[$parkingService->id] = $held;
+
+        foreach ($participantIndexes as $index) {
+            $participant = new ParticipantDto();
+            $participant->parkingService = $parkingService;
+            $bookingDto->participants[$index] = $participant;
+        }
+    }
 }