fix: stop offering unbookable services in the booking edit flow

src/Service/BookingEditSubmitGuard.php

@@ -24,9 +24,72 @@ class BookingEditSubmitGuard
 {
     public function __construct(
         private readonly BookingDataProcessor $bookingDataProcessor,
+        private readonly ServiceAvailabilityCalculator $serviceAvailabilityCalculator,
     ) {
     }
 
+    /**
+     * Reverts selections of services that are no longer bookable.
+     *
+     * The read-only state in the participant form is presentation only, so a stale session or
+     * a replayed POST can still carry a service that has since sold out or moved to 'Anfrage'.
+     * Sending one makes BusPro reject the entire update - every participant's changes with it -
+     * so the selection is reverted to what the live booking already holds.
+     *
+     * Services the participant already holds are never touched: the availability rule carves
+     * them out, and withdrawing one would break the Leistung/Teilnehmer counts.
+     *
+     * Expects $workingDto->booking to be the fresh booking, as the availability rule reads its
+     * already-held carve-out from there.
+     *
+     * @return list<string> Labels of the services that were reverted, for user feedback
+     */
+    public function revertUnbookableServiceAdditions(BookingDto $workingDto, Booking $freshBooking): array
+    {
+        $baselineDto = $this->bookingDataProcessor->createBookingDtoFromBooking($freshBooking, $workingDto->travel, $workingDto->isInternalAgencyBooking());
+        $revertedLabels = [];
+
+        foreach ($workingDto->participants as $index => $participant) {
+            $baseline = $baselineDto->participants[$index] ?? null;
+            if (null === $baseline) {
+                continue;
+            }
+
+            $isBlocked = fn (?Service $service): bool => null !== $service
+                && null !== $service->id
+                && $this->serviceAvailabilityCalculator->isServiceUnavailable($service->id, $workingDto, $index);
+
+            // Multi-selection fields: drop the blocked additions, keep everything else
+            foreach (['courses', 'additionalServices', 'board', 'rentals'] as $field) {
+                $kept = [];
+                foreach ($participant->{$field} as $service) {
+                    if (true === $isBlocked($service)) {
+                        $revertedLabels[] = (string) $service->label;
+                        continue;
+                    }
+                    $kept[] = $service;
+                }
+
+                if (count($kept) !== count($participant->{$field})) {
+                    $participant->{$field} = $kept;
+                }
+            }
+
+            // Single-selection fields: fall back to what the booking already holds rather than
+            // clearing, so a required field does not end up empty
+            foreach (['skiPass', 'veg', 'transportationOutbound', 'transportationInbound', 'parkingService'] as $field) {
+                if (false === $isBlocked($participant->{$field})) {
+                    continue;
+                }
+
+                $revertedLabels[] = (string) $participant->{$field}->label;
+                $participant->{$field} = $baseline->{$field};
+            }
+        }
+
+        return array_values(array_unique($revertedLabels));
+    }
+
     /**
      * Reverts immutable category changes to fresh booking values.
      *