fix: harden booking and meeting flows

lib/booking/slots.ts

@@ -1,4 +1,4 @@
-import type { Payload } from "payload";
+import type { Payload, PayloadRequest } from "payload";
 import { WEEKDAYS } from "@/collections/Availability";
 import { berlinParts, berlinWallTimeToUTC, type CalendarDate } from "@/lib/calendar/timezone";
 
@@ -63,17 +63,20 @@ function overlaps(aStart: Date, aEnd: Date, bStart: Date, bEnd: Date): boolean {
  */
 export async function getAvailableSlots(
   payload: Payload,
-  args: { durationMinutes: number; from: Date; to: Date },
+  args: { durationMinutes: number; from: Date; to: Date; req?: PayloadRequest },
 ): Promise<Map<string, TimeSlot[]>> {
-  const { durationMinutes, from, to } = args;
+  const { durationMinutes, from, to, req } = args;
   const result = new Map<string, TimeSlot[]>();
+  if (!Number.isInteger(durationMinutes) || durationMinutes <= 0 || durationMinutes > 1440 ||
+      !Number.isFinite(from.getTime()) || !Number.isFinite(to.getTime()) || to < from ||
+      to.getTime() - from.getTime() > 63 * 86400000) return result;
 
   const [{ docs: weekly }, { docs: overrides }, { docs: busyBookings }] = await Promise.all([
-    payload.find({ collection: "availability", where: { active: { equals: true } }, limit: 100 }),
+    payload.find({ collection: "availability", where: { active: { equals: true } }, pagination: false, req }),
     payload.find({
       collection: "availability-overrides",
       where: { and: [{ date: { greater_than_equal: from.toISOString() } }, { date: { less_than_equal: to.toISOString() } }] },
-      limit: 200,
+      pagination: false, req,
     }),
     payload.find({
       collection: "booking-requests",
@@ -84,7 +87,7 @@ export async function getAvailableSlots(
           { date: { less_than_equal: to.toISOString() } },
         ],
       },
-      limit: 500,
+      pagination: false, req,
     }),
   ]);
 
@@ -131,11 +134,11 @@ export async function getAvailableSlots(
         const slotEnd = atMinutesOfDay(day, start + durationMinutes);
         if (slotStart < now) continue;
         if (dayBusy.some((b) => overlaps(slotStart, slotEnd, b.start, b.end))) continue;
-        slots.push({ start: slotStart, end: slotEnd });
+        if (!slots.some((slot) => slot.start.getTime() === slotStart.getTime())) slots.push({ start: slotStart, end: slotEnd });
       }
     }
 
-    if (slots.length > 0) result.set(key, slots);
+    if (slots.length > 0) result.set(key, slots.sort((a, b) => a.start.getTime() - b.start.getTime()));
   }
 
   return result;