feat: wire slot reservation into all booking flows

Customer flow: reservation fires on Date/Time → Details transition with
re-validation on time slot tap and on 'Next' click to prevent simultaneous
bookings. 5-step flow: Service → Date/Time → Reserve → Details (countdown)
→ Payment & Review → Confirm. Guest users redirected to home on success.

Admin call-in: reserve slot before final submission (60min TTL).
Admin walk-in: reserve slot on modal open (5min TTL).

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent)

Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

frontend/src/lib/components/admin/BookingCreateModal.svelte

@@ -91,6 +91,12 @@
 
 	let submitting = $state(false);
 
+	// =============== Reservation State ===============
+	let reservationId = $state<string | null>(null);
+	let reservationExpiresAt = $state<Date | null>(null);
+	let reservationCountdown = $state<string>('');
+	let isReserving = $state(false);
+
 	// =============== Cache ===============
 	const workingHoursCache = new SvelteMap<string, Record<string, any>>();
 	const availableHoursCache = new SvelteMap<string, Record<string, any>>();
@@ -240,6 +246,13 @@
 		availableHoursCache.clear();
 		workingHours = null;
 		availableHours = null;
+		// Clear reservation state
+		reservationId = null;
+		reservationExpiresAt = null;
+		reservationCountdown = '';
+		if ((window as any).__bookingCreateCountdownInterval) {
+			clearInterval((window as any).__bookingCreateCountdownInterval);
+		}
 	}
 
 	// =============== Data Fetching ===============
@@ -346,6 +359,113 @@
 		}
 	}
 
+	// =============== Reservation ===============
+	async function reserveSlot(): Promise<boolean> {
+		if (!selectedUserId || !selectedDate || !selectedTime) {
+			return false;
+		}
+
+		isReserving = true;
+
+		try {
+			const localDate = selectedDate.toDate(getLocalTimeZone());
+			const [hours, minutes] = selectedTime.split(':').map(Number);
+			localDate.setHours(hours, minutes, 0, 0);
+			const startTimeISO = localDate.toISOString();
+
+			const serviceIds = selectedServices.map((s) => s.id);
+
+			// Build service overrides payload
+			const overrides = [];
+			for (const [serviceId, data] of Object.entries(serviceOverrides)) {
+				const durationChanged = parseInt(data.duration) !== data.originalDuration;
+				if (durationChanged) {
+					overrides.push({
+						service_id: serviceId,
+						override_duration_minutes: parseInt(data.duration)
+					});
+				}
+			}
+
+			const response = await fetch('/api/admin/bookings/reserve', {
+				method: 'POST',
+				headers: {
+					'Content-Type': 'application/json',
+					Authorization: `Bearer ${authStore.currentToken}`
+				},
+				body: JSON.stringify({
+					user_id: selectedUserId,
+					start_time: startTimeISO,
+					service_ids: serviceIds,
+					service_overrides: overrides.length > 0 ? overrides : [],
+					ttl_minutes: 60
+				})
+			});
+
+			if (response.ok) {
+				const data = await response.json();
+				reservationId = data.id;
+				reservationExpiresAt = new Date(data.expires_at);
+				startCountdown();
+				return true;
+			} else if (response.status === 409) {
+				toast.error('Slot no longer available, refreshing...');
+				// Refresh available hours
+				if (selectedDate) {
+					fetchHoursForMonth(selectedDate);
+				}
+				reservationId = null;
+				reservationExpiresAt = null;
+				reservationCountdown = '';
+				return false;
+			} else {
+				const errorText = await response.text();
+				toast.error(`Failed to reserve slot: ${errorText}`);
+				return false;
+			}
+		} catch (err) {
+			console.error('Reservation error:', err);
+			toast.error('Failed to reserve slot');
+			return false;
+		} finally {
+			isReserving = false;
+		}
+	}
+
+	function startCountdown() {
+		// Clear any existing interval
+		if ((window as any).__bookingCreateCountdownInterval) {
+			clearInterval((window as any).__bookingCreateCountdownInterval);
+		}
+
+		const updateCountdown = () => {
+			if (!reservationExpiresAt) {
+				reservationCountdown = '';
+				return;
+			}
+
+			const now = new Date();
+			const diff = reservationExpiresAt.getTime() - now.getTime();
+
+			if (diff <= 0) {
+				reservationCountdown = 'Expired';
+				reservationId = null;
+				reservationExpiresAt = null;
+				if ((window as any).__bookingCreateCountdownInterval) {
+					clearInterval((window as any).__bookingCreateCountdownInterval);
+				}
+				return;
+			}
+
+			const minutes = Math.floor(diff / 60000);
+			const seconds = Math.floor((diff % 60000) / 1000);
+			reservationCountdown = `${minutes}:${seconds.toString().padStart(2, '0')}`;
+		};
+
+		updateCountdown();
+		(window as any).__bookingCreateCountdownInterval = setInterval(updateCountdown, 1000);
+	}
+
 	// =============== Logic ===============
 	function toggleService(service: Service) {
 		const index = selectedServices.findIndex((s) => s.id === service.id);
@@ -600,6 +720,13 @@
 
 	// =============== Submission ===============
 	async function submitBooking() {
+		// First, reserve the slot
+		const reserved = await reserveSlot();
+		if (!reserved) {
+			submitting = false;
+			return;
+		}
+
 		submitting = true;
 
 		try {
@@ -1074,6 +1201,24 @@
 						</Card.Description>
 					</Card.Header>
 					<Card.Content class="space-y-4 p-0">
+						<!-- Reservation Countdown Banner -->
+						{#if reservationId && reservationExpiresAt}
+							<div class="mx-6 mt-4 rounded-lg bg-green-50 border border-green-200 p-3">
+								<div class="flex items-center justify-between">
+									<div class="flex items-center gap-2">
+										<svg class="h-5 w-5 text-green-600" fill="none" stroke="currentColor" viewBox="0 0 24 24">
+											<path stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M5 13l4 4L19 7"></path>
+										</svg>
+										<span class="text-sm font-medium text-green-800">
+											Slot reserved until {reservationExpiresAt.toLocaleTimeString([], { hour: '2-digit', minute: '2-digit' })}
+										</span>
+									</div>
+									<span class="text-sm font-mono font-semibold text-green-700">
+										({reservationCountdown} remaining)
+									</span>
+								</div>
+							</div>
+						{/if}
 						{#if loadingWorkingHours}
 							<div class="flex items-center justify-center p-6">
 								<p>Loading available dates...</p>
@@ -1184,11 +1329,11 @@
 					<Card.Footer class="flex justify-between">
 						<Button variant="outline" onclick={() => currentStep--}>Back</Button>
 						<Button
-							disabled={!canProceedStep4 || submitting}
+							disabled={!canProceedStep4 || submitting || isReserving}
 							onclick={submitBooking}
 							class="bg-primary text-primary-foreground"
 						>
-							{submitting ? 'Creating Booking...' : 'Create Booking'}
+							{isReserving ? 'Reserving Slot...' : submitting ? 'Creating Booking...' : 'Create Booking'}
 						</Button>
 					</Card.Footer>
 				</Card.Root>

frontend/src/lib/components/admin/WalkInBooking.svelte

@@ -5,6 +5,7 @@
 	import { CalendarDate } from '@internationalized/date';
 	import { SvelteDate } from 'svelte/reactivity';
 	import { onMount } from 'svelte';
+	import { toast } from 'svelte-sonner';
 
 	import type { AvailableHoursDay } from '$lib/types/booking';
 
@@ -14,12 +15,18 @@
 		waitMinutes?: number;
 		durationMinutes: number;
 		startTime?: string;
-		slotEndMinutes?: number; // Store for live countdown
+		slotEndMinutes?: number;
 	} | null>(null);
 	let loading = $state(true);
 	let noSlotsToday = $state(false);
 	let currentTime = $state(new Date());
 
+	// Reservation state for walk-in
+	let reservationId = $state<string | null>(null);
+	let reservationExpiresAt = $state<Date | null>(null);
+	let reservationCountdown = $state<string>('');
+	let isReserving = $state(false);
+
 	onMount(() => {
 		calculateSlotAvailability();
 
@@ -153,6 +160,119 @@
 		const displayHours = hours % 12 || 12;
 		return `${displayHours}:${minutes.toString().padStart(2, '0')} ${period}`;
 	}
+
+	async function reserveWalkInSlot(startTime: string): Promise<boolean> {
+		isReserving = true;
+
+		try {
+			const now = new SvelteDate();
+			const [hours, minutes] = startTime.split(':').map(Number);
+			const start = new SvelteDate(
+				now.getFullYear(),
+				now.getMonth(),
+				now.getDate(),
+				hours,
+				minutes,
+				0,
+				0
+			);
+			const startTimeISO = start.toISOString();
+
+			const response = await fetch('/api/admin/bookings/reserve', {
+				method: 'POST',
+				headers: {
+					'Content-Type': 'application/json',
+					Authorization: `Bearer ${authStore.currentToken}`
+				},
+				body: JSON.stringify({
+					user_id: null,
+					start_time: startTimeISO,
+					service_ids: [],
+					service_overrides: [],
+					ttl_minutes: 5
+				})
+			});
+
+			if (response.ok) {
+				const data = await response.json();
+				reservationId = data.id;
+				reservationExpiresAt = new Date(data.expires_at);
+				startWalkInCountdown();
+				return true;
+			} else if (response.status === 409) {
+				toast.error('Slot no longer available, please try again');
+				calculateSlotAvailability();
+				return false;
+			} else {
+				const errorText = await response.text();
+				toast.error(`Failed to reserve slot: ${errorText}`);
+				return false;
+			}
+		} catch (err) {
+			console.error('Reservation error:', err);
+			toast.error('Failed to reserve slot');
+			return false;
+		} finally {
+			isReserving = false;
+		}
+	}
+
+	function startWalkInCountdown() {
+		if ((window as any).__walkInCountdownInterval) {
+			clearInterval((window as any).__walkInCountdownInterval);
+		}
+
+		const updateCountdown = () => {
+			if (!reservationExpiresAt) {
+				reservationCountdown = '';
+				return;
+			}
+
+			const now = new Date();
+			const diff = reservationExpiresAt.getTime() - now.getTime();
+
+			if (diff <= 0) {
+				reservationCountdown = 'Expired';
+				reservationId = null;
+				reservationExpiresAt = null;
+				toast.error('Slot released — please re-check availability');
+				if ((window as any).__walkInCountdownInterval) {
+					clearInterval((window as any).__walkInCountdownInterval);
+				}
+				showCreateModal = false;
+				return;
+			}
+
+			const minutes = Math.floor(diff / 60000);
+			const seconds = Math.floor((diff % 60000) / 1000);
+			reservationCountdown = `${minutes}:${seconds.toString().padStart(2, '0')}`;
+		};
+
+		updateCountdown();
+		(window as any).__walkInCountdownInterval = setInterval(updateCountdown, 1000);
+	}
+
+	function handleStartWalkIn() {
+		if (slotInfo?.isAvailableNow) {
+			showCreateModal = true;
+		} else if (slotInfo?.startTime) {
+			reserveWalkInSlot(slotInfo.startTime).then((reserved) => {
+				if (reserved) {
+					showCreateModal = true;
+				}
+			});
+		}
+	}
+
+	function handleModalClose() {
+		showCreateModal = false;
+		reservationId = null;
+		reservationExpiresAt = null;
+		reservationCountdown = '';
+		if ((window as any).__walkInCountdownInterval) {
+			clearInterval((window as any).__walkInCountdownInterval);
+		}
+	}
 </script>
 
 <div class="rounded-lg border border-gray-200 bg-white p-4">
@@ -194,10 +314,10 @@
 
 	<div class="flex items-center gap-3">
 		<Button
-			onclick={() => (showCreateModal = true)}
-			disabled={noSlotsToday || (slotInfo?.isAvailableNow && (getLiveRemainingMinutes() ?? 0) <= 0)}
+			onclick={handleStartWalkIn}
+			disabled={noSlotsToday || isReserving || (slotInfo?.isAvailableNow && (getLiveRemainingMinutes() ?? 0) <= 0)}
 		>
-			Start Walk-In Session
+			{isReserving ? 'Reserving...' : 'Start Walk-In Session'}
 		</Button>
 	</div>
 </div>
@@ -207,5 +327,7 @@
 		bind:open={showCreateModal}
 		maxSlotDuration={slotInfo?.durationMinutes ?? 0}
 		availableStartTime={slotInfo?.isAvailableNow ? undefined : slotInfo?.startTime}
+		reservationExpiresAt={reservationExpiresAt}
+		onclose={handleModalClose}
 	/>
 {/if}

frontend/src/lib/components/admin/WalkInCreateModal.svelte

@@ -23,15 +23,19 @@
 	interface Props {
 		open: boolean;
 		maxSlotDuration?: number;
-		availableStartTime?: string; // "HH:MM" or "HH:MM:SS" format from the available slot
+		availableStartTime?: string;
+		reservationExpiresAt?: Date | null;
 		onBookingCreated?: () => void;
+		onclose?: () => void;
 	}
 
 	let {
 		open = $bindable(),
 		maxSlotDuration = 0,
 		availableStartTime,
-		onBookingCreated
+		reservationExpiresAt,
+		onBookingCreated,
+		onclose
 	}: Props = $props();
 
 	// =============== State ===============
@@ -64,6 +68,10 @@
 
 	let submitting = $state(false);
 
+	// Countdown state
+	let reservationCountdown = $state<string>('');
+	let isReservationExpired = $state(false);
+
 	// =============== Derived Helpers ===============
 	function getTotalDuration() {
 		return selectedServices.reduce((total, service) => {
@@ -123,6 +131,48 @@
 		}
 	});
 
+	// Handle reservation countdown
+	$effect(() => {
+		if (open && reservationExpiresAt) {
+			startCountdown();
+		} else {
+			reservationCountdown = '';
+			isReservationExpired = false;
+		}
+	});
+
+	function startCountdown() {
+		if ((window as any).__walkInModalCountdownInterval) {
+			clearInterval((window as any).__walkInModalCountdownInterval);
+		}
+
+		const updateCountdown = () => {
+			if (!reservationExpiresAt) {
+				reservationCountdown = '';
+				return;
+			}
+
+			const now = new Date();
+			const diff = reservationExpiresAt.getTime() - now.getTime();
+
+			if (diff <= 0) {
+				reservationCountdown = 'Expired';
+				isReservationExpired = true;
+				if ((window as any).__walkInModalCountdownInterval) {
+					clearInterval((window as any).__walkInModalCountdownInterval);
+				}
+				return;
+			}
+
+			const minutes = Math.floor(diff / 60000);
+			const seconds = Math.floor((diff % 60000) / 1000);
+			reservationCountdown = `${minutes}:${seconds.toString().padStart(2, '0')}`;
+		};
+
+		updateCountdown();
+		(window as any).__walkInModalCountdownInterval = setInterval(updateCountdown, 1000);
+	}
+
 	function resetState() {
 		currentStep = 1;
 		userType = 'member';
@@ -305,6 +355,8 @@
 				notes: notes.trim() || null
 			};
 
+			// TODO: When guest booking is fully implemented, ensure walk-in guest reservations properly transition to real bookings.
+
 			const res = await fetch('/api/admin/bookings', {
 				method: 'POST',
 				headers: {
@@ -366,6 +418,35 @@
 		</Modal.Header>
 
 		<div class="px-6 pb-4">
+			<!-- Reservation Countdown Banner -->
+			{#if reservationExpiresAt && !isReservationExpired}
+				<div class="mx-6 mt-4 rounded-lg bg-green-50 border border-green-200 p-3">
+					<div class="flex items-center justify-between">
+						<div class="flex items-center gap-2">
+							<svg class="h-5 w-5 text-green-600" fill="none" stroke="currentColor" viewBox="0 0 24 24">
+								<path stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M5 13l4 4L19 7"></path>
+							</svg>
+							<span class="text-sm font-medium text-green-800">
+								Slot held for
+							</span>
+						</div>
+						<span class="text-sm font-mono font-semibold text-green-700">
+							{reservationCountdown}
+						</span>
+					</div>
+				</div>
+			{:else if isReservationExpired}
+				<div class="mx-6 mt-4 rounded-lg bg-red-50 border border-red-200 p-3">
+					<div class="flex items-center gap-2">
+						<svg class="h-5 w-5 text-red-600" fill="none" stroke="currentColor" viewBox="0 0 24 24">
+							<path stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M12 8v4m0 4h.01M21 12a9 9 0 11-18 0 9 9 0 0118 0z"></path>
+						</svg>
+						<span class="text-sm font-medium text-red-800">
+							Slot released — please re-check availability
+						</span>
+					</div>
+				</div>
+			{/if}
 			<!-- Step 1: Customer Selection -->
 			{#if currentStep === 1}
 				<Card.Root>
@@ -717,7 +798,7 @@
 					<Card.Footer class="flex justify-between">
 						<Button variant="outline" onclick={() => currentStep--}>Back</Button>
 						<Button
-							disabled={submitting}
+							disabled={submitting || isReservationExpired}
 							onclick={submitBooking}
 							class="bg-primary text-primary-foreground"
 						>

frontend/src/lib/components/booking/BookingFlow.svelte

@@ -44,6 +44,105 @@
 	});
 	let isSubmitting = $state(false);
 
+	// =============== Slot Reservation System ===============
+	let reservationId = $state<string | null>(null);
+	let reservationExpiresAt = $state<Date | null>(null);
+	let reservationCountdown = $state<string>('');
+	let reservationExpired = $state(false);
+	let isReserving = $state(false);
+
+	// =============== Slot Reservation Functions ===============
+	async function reserveSlot() {
+		isReserving = true;
+		try {
+			if (!selectedDate || !selectedTime) {
+				toast.error('Please select a date and time');
+				return false;
+			}
+
+			const [hours, minutes] = selectedTime.split(':').map(Number);
+			const bookingDate = selectedDate.toDate(getLocalTimeZone());
+			bookingDate.setHours(hours, minutes, 0, 0);
+			const startTimeISO = bookingDate.toISOString();
+			const serviceIds = selectedServices.map((s) => s.id);
+
+			const response = await fetch('/api/bookings/reserve', {
+				method: 'POST',
+				headers: { 'Content-Type': 'application/json' },
+				body: JSON.stringify({ start_time: startTimeISO, service_ids: serviceIds })
+			});
+
+			if (!response.ok) {
+				const errorText = await response.text();
+				if (response.status === 429) {
+					toast.error('Too many active reservations. Please wait or log in.');
+				} else if (response.status === 409) {
+					toast.error('This time slot is no longer available. Please choose a different time.');
+					await refreshAvailableHours();
+				} else {
+					toast.error('Failed to reserve slot. Please try again.');
+				}
+				return false;
+			}
+
+			const data = await response.json();
+			reservationId = data.id;
+			reservationExpiresAt = new Date(data.expires_at);
+			reservationExpired = false;
+			startCountdown();
+			return true;
+		} catch (error) {
+			toast.error('Network error while reserving slot.');
+			return false;
+		} finally {
+			isReserving = false;
+		}
+	}
+
+	function startCountdown() {
+		if (!reservationExpiresAt) return;
+
+		const updateCountdown = () => {
+			if (!reservationExpiresAt) {
+				reservationCountdown = '';
+				return;
+			}
+
+			const now = new Date();
+			const diff = reservationExpiresAt.getTime() - now.getTime();
+
+			if (diff <= 0) {
+				reservationCountdown = '00:00';
+				reservationExpired = true;
+				reservationId = null;
+				reservationExpiresAt = null;
+				toast.error('Your reservation has expired. Please select a new time slot.');
+				return;
+			}
+
+			const minutes = Math.floor(diff / 60000);
+			const seconds = Math.floor((diff % 60000) / 1000);
+			reservationCountdown = `${String(minutes).padStart(2, '0')}:${String(seconds).padStart(2, '0')}`;
+		};
+
+		updateCountdown();
+		const interval = setInterval(() => {
+			if (reservationExpired) {
+				clearInterval(interval);
+				return;
+			}
+			updateCountdown();
+		}, 1000);
+	}
+
+	async function refreshAvailableHours() {
+		if (!selectedDate) return;
+
+		const monthKey = `${selectedDate.year}-${String(selectedDate.month).padStart(2, '0')}`;
+		availableHoursCache.delete(monthKey);
+		await fetchHoursForMonth(selectedDate);
+	}
+
 	// =============== Services Management ===============
 	let services = $state<Service[]>([]);
 	let servicesLoading = $state(true);
@@ -557,13 +656,55 @@
 		// Only clear if we're on the date/time selection step
 		if (currentStep === 2 && selectedDate) {
 			const monthKey = `${selectedDate.year}-${String(selectedDate.month).padStart(2, '0')}`;
-			availableHoursCache.delete(monthKey); // Only delete current month
+			availableHoursCache.delete(monthKey);
 			fetchHoursForMonth(selectedDate);
 		}
 
 		selectedTime = null;
 	}
 
+	// Select a time slot with server-side re-validation
+	async function selectTimeWithValidation(time: string) {
+		selectedTime = time;
+		await refreshAndValidateSlot();
+	}
+
+	// Re-fetch available hours and check if selectedTime is still available
+	async function refreshAndValidateSlot() {
+		if (!selectedDate || !selectedTime) return;
+
+		const monthKey = `${selectedDate.year}-${String(selectedDate.month).padStart(2, '0')}`;
+		availableHoursCache.delete(monthKey);
+		await fetchHoursForMonth(selectedDate);
+
+		const dateStr = selectedDate.toString();
+		const dayAvailable = availableHours?.[dateStr]?.slots;
+		if (!dayAvailable || dayAvailable.length === 0) {
+			toast.error('Sorry, this slot is no longer available. Please choose a different time.');
+			selectedTime = null;
+			return false;
+		}
+
+		const duration = getTotalDuration();
+		const [selHour, selMinute] = selectedTime.split(':').map(Number);
+		const selStart = selHour * 60 + selMinute;
+		const selEnd = selStart + duration;
+
+		const stillAvailable = dayAvailable.some(slot => {
+			const [sH, sM] = slot.startTime.split(':').map(Number);
+			const [eH, eM] = slot.endTime.split(':').map(Number);
+			return selStart >= (sH * 60 + sM) && selEnd <= (eH * 60 + eM);
+		});
+
+		if (!stillAvailable) {
+			toast.error('Sorry, this slot was just taken. Please choose a different time.');
+			selectedTime = null;
+			return false;
+		}
+
+		return true;
+	}
+
 	function formatDuration(minutes: number): string {
 		const hours = Math.floor(minutes / 60);
 		const remainingMinutes = minutes % 60;
@@ -610,8 +751,16 @@
 	);
 
 	// =============== Navigation ===============
-	function nextStep() {
-		if (currentStep < 4) {
+	async function nextStep() {
+		// Step 2 -> Step 3: Re-validate slot, then reserve
+		if (currentStep === 2) {
+			const slotStillFree = await refreshAndValidateSlot();
+			if (!slotStillFree) return;
+			const reserved = await reserveSlot();
+			if (!reserved) return;
+		}
+
+		if (currentStep < 5) {
 			currentStep++;
 			setTimeout(() => {
 				window.scrollTo({ top: 0, behavior: 'smooth' });
@@ -632,7 +781,7 @@
 	const canProceedStep1 = $derived(selectedServices.length > 0);
 	const canProceedStep2 = $derived(!!(selectedDate && selectedTime));
 	const canProceedStep3 = $derived(
-		authStore.isAuthenticated
+		(authStore.isAuthenticated
 			? !!(
 					authStore.currentUser?.firstName &&
 					authStore.currentUser?.lastName &&
@@ -644,8 +793,9 @@
 					customerInfo.lastName &&
 					customerInfo.email &&
 					customerInfo.phone
-				)
+				)) && !reservationExpired
 	);
+	const canProceedStep4 = $derived(true);
 
 	// =============== Submission ===============
 	async function submitBooking() {
@@ -666,21 +816,56 @@
 			// Extract service IDs
 			const serviceIds = selectedServices.map((s) => s.id);
 
+			// For guest users, create a guest account first
+			let guestUserId: string | null = null;
+			if (!authStore.isAuthenticated) {
+				const guestResponse = await fetch('/api/users/guest', {
+					method: 'POST',
+					headers: { 'Content-Type': 'application/json' },
+					body: JSON.stringify({
+						firstName: customerInfo.firstName,
+						lastName: customerInfo.lastName,
+						email: customerInfo.email,
+						phone: customerInfo.phone
+					})
+				});
+
+				if (!guestResponse.ok) {
+					const errorText = await guestResponse.text();
+					if (guestResponse.status === 409) {
+						toast.error('Email already registered — please log in to book.');
+					} else {
+						toast.error('Failed to create guest account. Please try again.');
+					}
+					isSubmitting = false;
+					return;
+				}
+
+				const guestData = await guestResponse.json();
+				guestUserId = guestData.id;
+			}
+
 			// Build request body
-			const requestBody = {
+			const requestBody: Record<string, unknown> = {
 				service_ids: serviceIds,
 				start_time: startTimeISO,
 				notes: customerInfo.specialRequests || null
 			};
 
+			if (guestUserId) {
+				requestBody.user_id = guestUserId;
+			}
+
 			console.log('Submitting booking:', requestBody);
 
+			const headers: Record<string, string> = { 'Content-Type': 'application/json' };
+			if (authStore.currentToken) {
+				headers['Authorization'] = `Bearer ${authStore.currentToken}`;
+			}
+
 			const response = await fetch('/api/bookings', {
 				method: 'POST',
-				headers: {
-					'Content-Type': 'application/json',
-					Authorization: `Bearer ${authStore.currentToken}`
-				},
+				headers,
 				body: JSON.stringify(requestBody)
 			});
 
@@ -701,14 +886,18 @@
 				
 				toast.success(`Booking confirmed for ${bookingDateStr} at ${bookingTimeStr}!`);
 				
-				// Reset form and redirect to account page
+				// Clear reservation state
+				reservationId = null;
+				reservationExpiresAt = null;
+				
+				// Reset form and redirect
 				selectedServices = [];
 				selectedDate = undefined;
 				selectedTime = null;
 				currentStep = 1;
 				
-				// Navigate to account page to see bookings
-				window.location.href = '/account';
+				// Navigate to account page (logged-in) or home (guest)
+				window.location.href = authStore.isAuthenticated ? '/account' : '/';
 			} else {
 				// Handle error response
 				const errorText = await response.text();
@@ -760,7 +949,7 @@
 		<p class="text-gray-600">Professional beauty treatments in a calm and friendly environment</p>
 	</div>
 
-	<StepIndicator {currentStep} />
+	<StepIndicator {currentStep} steps={['Service', 'Date & Time', 'Details', 'Payment & Review', 'Confirm']} />
 
 	<!-- Step 1: Service Selection -->
 	{#if currentStep === 1}
@@ -857,7 +1046,7 @@
 								{selectedTime}
 								formattedDate={formattedSelectedDate}
 								onselect={(time) => {
-									selectedTime = time;
+									selectTimeWithValidation(time);
 								}}
 								lunchProtectionStatus={lunchProtectionStatus()}
 							/>
@@ -916,6 +1105,18 @@
 				<Card.Description>Please confirm your contact information</Card.Description>
 			</Card.Header>
 			<Card.Content class="space-y-6">
+				{#if reservationExpired}
+					<div class="rounded-lg bg-red-50 p-4 text-center">
+						<p class="text-red-600">Reservation expired — please go back and select a new time</p>
+					</div>
+				{:else}
+					<div class="rounded-lg bg-blue-50 p-4 text-center">
+						<p class="text-blue-700">
+							Your slot is reserved for {reservationCountdown} — complete your booking before time expires
+						</p>
+					</div>
+				{/if}
+
 				<BookingSummary
 					services={selectedServices}
 					date={selectedDate}
@@ -994,18 +1195,18 @@
 					onclick={nextStep}
 					class="bg-primary text-primary-foreground"
 				>
-					Next: Payment
+					{reservationExpired ? 'Reservation Expired' : 'Next: Review & Payment'}
 				</Button>
 			</Card.Footer>
 		</Card.Root>
 	{/if}
 
-	<!-- Step 4: Payment (complete) -->
+	<!-- Step 4: Payment & Review -->
 	{#if currentStep === 4}
 		<Card.Root>
 			<Card.Header>
-				<Card.Title>Payment Confirmation</Card.Title>
-				<Card.Description>Review and complete your booking</Card.Description>
+				<Card.Title>Payment & Review</Card.Title>
+				<Card.Description>Review your booking details</Card.Description>
 			</Card.Header>
 			<Card.Content class="space-y-6">
 				<BookingSummary
@@ -1024,7 +1225,7 @@
 					showCustomer={true}
 				/>
 
-				<!-- Payment form placeholder -->
+				<!-- TODO: Integrate payment processor (Stripe/Square) here. Current flow: logged-in users go straight to confirmation, guest users show payment step before confirmation. -->
 				<div class="rounded-lg bg-white p-6">
 					<h2 class="mb-4 text-2xl font-semibold">Payment</h2>
 					<p class="text-gray-600">Square payment integration will be added here.</p>
@@ -1033,11 +1234,38 @@
 			<Card.Footer class="flex justify-between">
 				<Button variant="outline" onclick={prevStep}>Back</Button>
 				<Button
-					disabled={!canProceedStep3 || isSubmitting}
+					disabled={isSubmitting}
+					onclick={nextStep}
+					class="bg-primary text-primary-foreground"
+				>
+					Next: Confirm
+				</Button>
+			</Card.Footer>
+		</Card.Root>
+	{/if}
+
+	<!-- Step 5: Confirm -->
+	{#if currentStep === 5}
+		<Card.Root>
+			<Card.Header>
+				<Card.Title>Confirm Your Booking</Card.Title>
+				<Card.Description>Ready to confirm your appointment</Card.Description>
+			</Card.Header>
+			<Card.Content class="space-y-6">
+				<div class="rounded-lg bg-gray-50 p-6 text-center">
+					<p class="text-lg">
+						Ready to confirm: {selectedServices.map((s) => s.name).join(', ')} on {selectedDate?.toDate(getLocalTimeZone()).toLocaleDateString('en-GB', { weekday: 'long', day: 'numeric', month: 'long' })} at {selectedTime}
+					</p>
+				</div>
+			</Card.Content>
+			<Card.Footer class="flex justify-between">
+				<Button variant="outline" onclick={prevStep}>Back</Button>
+				<Button
+					disabled={isSubmitting}
 					onclick={submitBooking}
 					class="bg-primary text-primary-foreground"
 				>
-					{isSubmitting ? 'Processing...' : 'Complete Booking'}
+					{isSubmitting ? 'Processing...' : 'Confirm Booking'}
 				</Button>
 			</Card.Footer>
 		</Card.Root>