fix: prevent BookingDetailsSheet flicker when switching bookings (#27894)

Co-authored-by: Devin AI <158243242+devin-ai-integration[bot]@users.noreply.github.com>

apps/web/modules/bookings/components/BookingDetailsSheet.test.tsx

@@ -0,0 +1,144 @@
+import { act, renderHook } from "@testing-library/react";
+import React from "react";
+import { beforeEach, describe, expect, it, vi } from "vitest";
+import { createStore, useStore } from "zustand";
+import type { BookingOutput } from "../types";
+
+type BookingDetailsSheetStore = {
+  selectedBookingUid: string | null;
+  bookings: BookingOutput[];
+  setSelectedBookingUid: (uid: string | null) => void;
+  setBookings: (bookings: BookingOutput[]) => void;
+  getSelectedBooking: () => BookingOutput | null;
+};
+
+function createTestStore(initialBookings: BookingOutput[] = []) {
+  return createStore<BookingDetailsSheetStore>((set, get) => ({
+    selectedBookingUid: null,
+    bookings: initialBookings,
+    setSelectedBookingUid: (uid) => set({ selectedBookingUid: uid }),
+    setBookings: (bookings) => set({ bookings }),
+    getSelectedBooking: () => {
+      const state = get();
+      if (!state.selectedBookingUid) return null;
+      return state.bookings.find((booking) => booking.uid === state.selectedBookingUid) ?? null;
+    },
+  }));
+}
+
+const makeBooking = (uid: string, title: string): BookingOutput =>
+  ({
+    uid,
+    id: Number(uid),
+    title,
+    startTime: new Date().toISOString(),
+    endTime: new Date().toISOString(),
+    status: "ACCEPTED",
+    attendees: [],
+    metadata: null,
+    location: null,
+    rescheduled: false,
+    recurringEventId: null,
+    fromReschedule: null,
+    responses: {},
+    payment: [],
+    eventType: null,
+    user: null,
+    assignmentReasonSortedByCreatedAt: [],
+  }) as unknown as BookingOutput;
+
+describe("BookingDetailsSheet transition behavior", () => {
+  const bookingA = makeBooking("uid-a", "Booking A");
+  const bookingB = makeBooking("uid-b", "Booking B");
+
+  it("getSelectedBooking returns null when no uid is selected", () => {
+    const store = createTestStore([bookingA, bookingB]);
+    expect(store.getState().getSelectedBooking()).toBeNull();
+  });
+
+  it("getSelectedBooking returns the correct booking when uid is set", () => {
+    const store = createTestStore([bookingA, bookingB]);
+    store.getState().setSelectedBookingUid("uid-a");
+    expect(store.getState().getSelectedBooking()?.uid).toBe("uid-a");
+  });
+
+  it("getSelectedBooking returns null when uid does not match any booking", () => {
+    const store = createTestStore([bookingA, bookingB]);
+    store.getState().setSelectedBookingUid("uid-nonexistent");
+    expect(store.getState().getSelectedBooking()).toBeNull();
+  });
+
+  it("switching between bookings updates getSelectedBooking immediately", () => {
+    const store = createTestStore([bookingA, bookingB]);
+    store.getState().setSelectedBookingUid("uid-a");
+    expect(store.getState().getSelectedBooking()?.title).toBe("Booking A");
+
+    store.getState().setSelectedBookingUid("uid-b");
+    expect(store.getState().getSelectedBooking()?.title).toBe("Booking B");
+  });
+
+  describe("lastBookingRef fallback logic", () => {
+    it("preserves last booking when getSelectedBooking returns null during transition", () => {
+      let lastBooking: BookingOutput | null = null;
+      let selectedBookingUid: string | null = null;
+
+      const store = createTestStore([bookingA, bookingB]);
+      store.getState().setSelectedBookingUid("uid-a");
+
+      const booking = store.getState().getSelectedBooking();
+      if (booking) {
+        lastBooking = booking;
+      }
+
+      store.getState().setSelectedBookingUid("uid-nonexistent");
+      selectedBookingUid = store.getState().selectedBookingUid;
+
+      const currentBooking = store.getState().getSelectedBooking();
+      const displayBooking = currentBooking ?? lastBooking;
+
+      expect(currentBooking).toBeNull();
+      expect(selectedBookingUid).toBe("uid-nonexistent");
+      expect(displayBooking?.uid).toBe("uid-a");
+    });
+
+    it("clears lastBooking when selectedBookingUid is explicitly null", () => {
+      let lastBooking: BookingOutput | null = null;
+
+      const store = createTestStore([bookingA]);
+      store.getState().setSelectedBookingUid("uid-a");
+
+      const booking = store.getState().getSelectedBooking();
+      if (booking) {
+        lastBooking = booking;
+      }
+
+      store.getState().setSelectedBookingUid(null);
+      const selectedBookingUid = store.getState().selectedBookingUid;
+
+      if (!selectedBookingUid) {
+        lastBooking = null;
+      }
+
+      const currentBooking = store.getState().getSelectedBooking();
+      const displayBooking = currentBooking ?? lastBooking;
+
+      expect(displayBooking).toBeNull();
+    });
+
+    it("updates lastBooking when new booking is found", () => {
+      let lastBooking: BookingOutput | null = null;
+
+      const store = createTestStore([bookingA, bookingB]);
+
+      store.getState().setSelectedBookingUid("uid-a");
+      const bookingAResult = store.getState().getSelectedBooking();
+      if (bookingAResult) lastBooking = bookingAResult;
+      expect(lastBooking?.uid).toBe("uid-a");
+
+      store.getState().setSelectedBookingUid("uid-b");
+      const bookingBResult = store.getState().getSelectedBooking();
+      if (bookingBResult) lastBooking = bookingBResult;
+      expect(lastBooking?.uid).toBe("uid-b");
+    });
+  });
+});

apps/web/modules/bookings/components/BookingDetailsSheet.tsx

@@ -34,7 +34,7 @@ import { ExternalLinkIcon, RepeatIcon } from "@coss/ui/icons";
 import { BookingHistory } from "@calcom/web/modules/booking-audit/components/BookingHistory";
 import assignmentReasonBadgeTitleMap from "@lib/booking/assignmentReasonBadgeTitleMap";
 import Link from "next/link";
-import { useMemo } from "react";
+import { useMemo, useRef } from "react";
 import type { z } from "zod";
 import { AcceptBookingButton } from "../../../components/booking/AcceptBookingButton";
 import { BookingActionsDropdown } from "../../../components/booking/actions/BookingActionsDropdown";
@@ -64,14 +64,25 @@ export function BookingDetailsSheet({
   bookingAuditEnabled = false,
 }: BookingDetailsSheetProps) {
   const booking = useBookingDetailsSheetStore((state) => state.getSelectedBooking());
+  const selectedBookingUid = useBookingDetailsSheetStore((state) => state.selectedBookingUid);
+  const lastBookingRef = useRef<BookingOutput | null>(null);
 
-  // Return null if no booking is selected (sheet is closed)
-  if (!booking) return null;
+  if (booking) {
+    lastBookingRef.current = booking;
+  }
+
+  if (!selectedBookingUid) {
+    lastBookingRef.current = null;
+  }
+
+  const displayBooking = booking ?? lastBookingRef.current;
+
+  if (!displayBooking) return null;
 
   return (
     <BookingActionsStoreProvider>
       <BookingDetailsSheetInner
-        booking={booking}
+        booking={displayBooking}
         userTimeZone={userTimeZone}
         userTimeFormat={userTimeFormat}
         userId={userId}
@@ -224,16 +235,13 @@ function BookingDetailsSheetInner({
         className="overflow-y-auto pb-0 sm:pb-0"
         hideOverlay
         onInteractOutside={(e) => {
-          // Check if the click is on a booking list item
           const target = e.target as HTMLElement;
-          const isBookingListItem = target.closest("[data-booking-list-item]");
+          const isBookingItem =
+            target.closest("[data-booking-list-item]") || target.closest("[data-booking-calendar-event]");
 
-          if (isBookingListItem) {
-            // Prevent closing when clicking a booking list item
-            // The item's onClick will handle opening the sheet with the new booking
+          if (isBookingItem) {
             e.preventDefault();
           }
-          // If clicking elsewhere, allow the default behavior (close the sheet)
         }}>
         <SheetHeader showCloseButton={false} className="mt-0 w-full">
           <div className="flex items-center justify-between gap-x-4">

apps/web/modules/calendars/weeklyview/components/event/Event.tsx

@@ -1,11 +1,9 @@
-import { cva } from "class-variance-authority";
-
 import dayjs from "@calcom/dayjs";
+import type { CalendarEvent } from "@calcom/features/calendars/weeklyview/types/events";
 import type { BookingStatus } from "@calcom/prisma/enums";
 import classNames from "@calcom/ui/classNames";
 import { Tooltip } from "@calcom/ui/components/tooltip";
-
-import type { CalendarEvent } from "@calcom/features/calendars/weeklyview/types/events";
+import { cva } from "class-variance-authority";
 
 type EventProps = {
   event: CalendarEvent;
@@ -111,6 +109,7 @@ export function Event({
   return (
     <Tooltip content={tooltipContent} className="max-w-none" side={tooltipSide}>
       <Component
+        data-booking-calendar-event="true"
         onClick={() => onEventClick?.(event)} // Note this is not the button event. It is the calendar event.
         className={classNames(
           eventClasses({