Created and activated the booking integrity ExecPlan, then implemented staff availability, overlap prevention, and duration validation with backend tests.

Added a staff availability model and migration, a booking validation service, and serializer enforcement.

backend/apps/bookings/serializers.py

@@ -1,7 +1,6 @@
 from rest_framework import serializers
-from django.utils.translation import gettext_lazy as _
-
 from apps.bookings.models import Booking
+from apps.bookings.services import validate_booking_request
 from apps.salons.models import Service, StaffProfile
 
 
@@ -42,12 +41,12 @@ class BookingCreateSerializer(serializers.ModelSerializer):
     class Meta:
         model = Booking
         fields = ["service", "staff", "start_time", "end_time", "notes"]
+        extra_kwargs = {"staff": {"required": True}}
 
     def validate(self, attrs):
         service: Service = attrs["service"]
         staff = attrs.get("staff")
-        if staff and staff.salon_id != service.salon_id:
-            raise serializers.ValidationError(_("Selected staff does not belong to this salon"))
+        validate_booking_request(service, staff, attrs["start_time"], attrs["end_time"])
         return attrs
 
     def create(self, validated_data):