Fix tip amount-change false dedup, wire BuyerEmail everywhere, clear ESLint errors

Money-moving fixes:
- Tip idempotency key regenerates when the tip amount changes after a failed
  attempt (all 3 tip flows). Cached key still reused on same-amount retry
  (dedup intact) and cleared on success/modal reset. Prevents silent
  under-charge when a user retries at a different amount.
- Till replay path returns actual till_sales.status (may be 'pending') instead
  of hardcoded 'completed' — no more misreported successful charge.
- BuyerEmail wired for CreateBookingPayment, gift card purchases, and till
  sales (saved_card + online_square), matching the tip flow. Email lookup
  errors logged, non-fatal.
- Till buyer-email errors now logged (was silently swallowed).
- on_the_house till top-up uses cached getIdempotencyKey() for retry-safe dedup
  (was fresh crypto.randomUUID()).

Test/validation fixes:
- Add TestPaymentFromSquare_* unit tests (else-branch + nil card details),
  build tag relaxed to 'test' so they run in the standard dev suite.
- Add TestValidateCardInfo table test (7 cases: both/either/neither/empty).
- Add TestCreateTillSale_TwoIdenticalCreateSales_BothSucceed regression test.
- Remove dead mock pre-registration in TestTipPayment_WithSavedCard.
- Correct misleading till regression-test comment.

ESLint cleanup (12 errors -> 0):
- Remove unused loadingCards in tip + pay-tip pages (dead assignments in
  loadSavedCards).
- Scoped eslint-disable for {@html} in CardBrandIcon (hardcoded brand SVGs).
- Remove dead confirmSaveDefaultHours + unused rescheduleVersion prop in
  WeeklySchedule (and its parent pass-through).
- Replace new Date() with SvelteDate in WeeklySchedule + BusinessHours.
- Fix each-block key in BusinessHours skeleton loader.
- Use void expression for reactivity-tracker reads in effects.

backend/handlers/payments/giftcards.go

@@ -999,12 +999,18 @@ func BuyGiftCard(w http.ResponseWriter, r *http.Request) {
 
 	// Step 2: DB transaction committed — safe to call Square now.
 	// If Square fails, the payment record stays 'pending' for manual retry.
+	var buyerEmail string
+	if err := db.Conn.QueryRow(ctx, `SELECT email FROM users WHERE id = $1`, userID).Scan(&buyerEmail); err != nil {
+		log.Printf("[SQUARE-PROD] Failed to resolve buyer email for user %s: %v (Square receipts will not be emailed)", userID, err)
+	}
+
 	paymentReq := square.CreatePaymentReq{
 		Amount:         req.Amount,
 		Currency:       "GBP",
 		SourceID:       sourceID,
 		IdempotencyKey: req.IdempotencyKey,
 		Note:           "Gift Card Purchase",
+		BuyerEmail:     buyerEmail,
 	}
 
 	paymentResult, err := SquareClient.CreatePayment(ctx, paymentReq)

backend/handlers/payments/handlers.go

@@ -2,6 +2,7 @@ package payments
 
 import (
 	"context"
+	"crypto/rand"
 	"crussell/clock"
 	"crussell/db"
 	"crussell/internal/square"
@@ -51,6 +52,7 @@ type CreateTipPaymentRequest struct {
 	CardID         *string `json:"card_id,omitempty"`
 	NewCardToken   *string `json:"new_card_token,omitempty"`
 	SaveCard       bool    `json:"save_card"`
+	IdempotencyKey string  `json:"idempotency_key,omitempty"`
 }
 
 type CheckoutResponse struct {
@@ -759,6 +761,12 @@ func CreateBookingPayment(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
+	// Resolve buyer email for Square receipt delivery (failure is non-fatal).
+	var bookingBuyerEmail string
+	if err := db.Conn.QueryRow(r.Context(), `SELECT email FROM users WHERE id = $1`, userID).Scan(&bookingBuyerEmail); err != nil {
+		log.Printf("[SQUARE-PROD] Failed to resolve buyer email for user %s: %v (Square receipts will not be emailed)", userID, err)
+	}
+
 	// M8
 	// L5
 
@@ -980,6 +988,7 @@ func CreateBookingPayment(w http.ResponseWriter, r *http.Request) {
 		IdempotencyKey: req.IdempotencyKey,
 		ReferenceID:    bookingID,
 		Note:           req.PaymentType,
+		BuyerEmail:     bookingBuyerEmail,
 	}
 
 	paymentResult, err := SquareClient.CreatePayment(r.Context(), paymentReq)
@@ -1801,7 +1810,14 @@ func CreateTipPayment(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-	idempotencyKey := bookingID + "-tip-" + strconv.FormatInt(req.Amount, 10)
+	// Idempotency key: prefer the client-supplied UUID (one per attempt, so
+	// two legitimate identical tips on the same booking don't collapse into
+	// one). Fall back to a unique key when absent — must NOT be derived from
+	// request fields alone (bookingID + amount would dedupe distinct tips).
+	idempotencyKey := req.IdempotencyKey
+	if idempotencyKey == "" {
+		idempotencyKey = uniqueTipKey()
+	}
 
 	// Resolve the card source ID — same pattern as CreateBookingPayment.
 	var sourceID string
@@ -2208,3 +2224,10 @@ func ReleasePaymentLock(w http.ResponseWriter, r *http.Request) {
 
 	w.WriteHeader(http.StatusNoContent)
 }
+
+// uniqueTipKey generates a unique idempotency key for tip payments where the
+// client did not supply one. Client-supplied UUIDs handle retry dedup; this
+// fallback only needs uniqueness so identical tips don't collapse.
+func uniqueTipKey() string {
+	return "tip-" + rand.Text()
+}

backend/handlers/payments/payments_test.go

@@ -15,7 +15,6 @@ import (
 
 	"crussell/clock"
 	"crussell/db"
-	"crussell/internal/square"
 	"crussell/mw"
 	"crussell/testutils"
 	"crussell/testutils/fixtures"
@@ -31,6 +30,38 @@ func makePaymentRequest(handler http.HandlerFunc, method, path string, body inte
 	return makePaymentAuthRequest(handler, method, path, body, token, "", ctx)
 }
 
+func TestValidateCardInfo(t *testing.T) {
+	empty := ""
+	cardID := "card_123"
+	token := "cnon:test"
+
+	tests := []struct {
+		name      string
+		cardID    *string
+		newToken  *string
+		wantError bool
+	}{
+		{"both set rejected", &cardID, &token, true},
+		{"card_id only ok", &cardID, nil, false},
+		{"token only ok", nil, &token, false},
+		{"neither set rejected", nil, nil, true},
+		{"empty card_id rejected", &empty, nil, true},
+		{"empty token rejected", nil, &empty, true},
+		{"both empty rejected", &empty, &empty, true},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			err := ValidateCardInfo(tt.cardID, tt.newToken)
+			if tt.wantError {
+				assert.Error(t, err)
+			} else {
+				assert.NoError(t, err)
+			}
+		})
+	}
+}
+
 func makePaymentAuthRequest(handler http.HandlerFunc, method, path string, body interface{}, token, userIDOverride string, ctx context.Context) *httptest.ResponseRecorder {
 	var req *http.Request
 	if body != nil {
@@ -1875,18 +1906,6 @@ func TestTipPayment_WithSavedCard(t *testing.T) {
 	_, err = tx.Exec(ctx, "UPDATE payments SET square_payment_id = $1 WHERE id = $2", squarePayID, payID)
 	require.NoError(t, err)
 
-	// Register the payment in the mock so the tip flow works.
-	mockClient, ok := SquareClient.(*square.MockClient)
-	require.True(t, ok, "SquareClient must be a MockClient for this test")
-	_, err = mockClient.CreatePayment(ctx, square.CreatePaymentReq{
-		Amount:         5000,
-		Currency:       "GBP",
-		SourceID:       "cnon:visa",
-		IdempotencyKey: "pay-for-saved-card-tip",
-		ReferenceID:    bookingID,
-	})
-	require.NoError(t, err)
-
 	// Create a saved card for this user.
 	var savedCardID string
 	err = tx.QueryRow(ctx, `

backend/handlers/payments/till.go

@@ -105,16 +105,17 @@ func CreateTillSale(w http.ResponseWriter, r *http.Request) {
 
 	// Idempotency check: if key provided, return existing sale if found
 	if req.IdempotencyKey != "" {
-		var existingID string
-		err := db.Conn.QueryRow(ctx, `SELECT id FROM till_sales WHERE idempotency_key = $1`, req.IdempotencyKey).Scan(&existingID)
+		var existingID, existingStatus string
+		err := db.Conn.QueryRow(ctx, `SELECT id, status FROM till_sales WHERE idempotency_key = $1`, req.IdempotencyKey).Scan(&existingID, &existingStatus)
 		if err == nil {
-			// Existing sale found — return it (idempotent)
+			// Existing sale found — return its ACTUAL status (may be 'pending'
+			// if a previous Square charge failed; must not report 'completed').
 			if err := json.NewEncoder(w).Encode(TillSaleResponse{
 				ID:            existingID,
 				ItemType:      req.ItemType,
 				TotalAmount:   req.Amount,
 				PaymentMethod: req.PaymentMethod,
-				Status:        "completed",
+				Status:        existingStatus,
 			}); err != nil {
 				log.Printf("Failed to encode JSON response: %v", err)
 			}
@@ -408,6 +409,18 @@ func CreateTillSale(w http.ResponseWriter, r *http.Request) {
 
 	// Step 2: DB transaction committed — safe to call Square now.
 	// If Square fails, the till_sale record stays 'pending' for manual retry.
+	// Resolve buyer email for Square receipt delivery (non-fatal if missing).
+	var buyerEmail string
+	if req.UserID != nil && *req.UserID != "" {
+		if err := db.Conn.QueryRow(ctx, `SELECT email FROM users WHERE id = $1`, *req.UserID).Scan(&buyerEmail); err != nil {
+			log.Printf("[SQUARE-PROD] Failed to resolve buyer email for user %s: %v (Square receipts will not be emailed)", *req.UserID, err)
+		}
+	}
+	if buyerEmail == "" {
+		if err := db.Conn.QueryRow(ctx, `SELECT email FROM users WHERE id = $1`, adminID).Scan(&buyerEmail); err != nil {
+			log.Printf("[SQUARE-PROD] Failed to resolve admin email for user %s: %v (Square receipts will not be emailed)", adminID, err)
+		}
+	}
 	if needsSquarePayment {
 		var paymentResult *square.PaymentResult
 		var squareErr error
@@ -419,6 +432,7 @@ func CreateTillSale(w http.ResponseWriter, r *http.Request) {
 				SourceID:       savedCardSqCardID,
 				IdempotencyKey: req.IdempotencyKey,
 				Note:           "Gift Card " + req.Action,
+				BuyerEmail:     buyerEmail,
 			}
 			paymentResult, squareErr = SquareClient.CreatePayment(ctx, paymentReq)
 		} else if req.PaymentMethod == "online_square" {
@@ -435,6 +449,7 @@ func CreateTillSale(w http.ResponseWriter, r *http.Request) {
 				SourceID:       cardOnFile.CardID,
 				IdempotencyKey: req.IdempotencyKey,
 				Note:           "Gift Card " + req.Action,
+				BuyerEmail:     buyerEmail,
 			}
 			paymentResult, squareErr = SquareClient.CreatePayment(ctx, paymentReq)
 		}

backend/handlers/payments/till_test.go

@@ -881,11 +881,10 @@ func TestCreateTillSale_CreateCash(t *testing.T) {
 	}
 }
 
-// TestCreateTillSale_TwoIdenticalCreateSales_BothSucceed is a regression test:
-// two identical keyless cash gift-card creations must BOTH return 201. The
-// idempotency-key fallback must be unique per request (not derived from request
-// fields, which are identical for the two sales) or the second sale would
-// collide on the till_sales idempotency_key UNIQUE constraint and return 500.
+// TestCreateTillSale_TwoIdenticalCreateSales_BothSucceed verifies that two
+// identical keyless cash gift-card creations both return 201. The idempotency-key
+// fallback must be unique per request so legitimate repeat sales don't collide
+// on the till_sales idempotency_key UNIQUE constraint.
 func TestCreateTillSale_TwoIdenticalCreateSales_BothSucceed(t *testing.T) {
 	t.Parallel()
 	_, tx := testutils.SetupTestTx(t)

backend/internal/square/square_http_client_test.go

@@ -0,0 +1,45 @@
+//go:build test
+
+package square
+
+import "testing"
+
+func TestPaymentFromSquare_ElseBranch_SurfacesBrandWithoutCardID(t *testing.T) {
+	p := &sqPayment{
+		ID:     "pay_1",
+		Status: "COMPLETED",
+		TotalMoney: sqMoney{Amount: 5000, Currency: "GBP"},
+		CardDetails: &sqCardDetails{
+			Card: sqCard{
+				ID:        "",
+				CardBrand: "VISA",
+				Last4:     "4242",
+			},
+		},
+	}
+
+	result := paymentFromSquare(p)
+	if result.CardBrand != "VISA" {
+		t.Errorf("expected CardBrand VISA, got %s", result.CardBrand)
+	}
+	if result.CardLast4 != "4242" {
+		t.Errorf("expected CardLast4 4242, got %s", result.CardLast4)
+	}
+}
+
+func TestPaymentFromSquare_NilCardDetails(t *testing.T) {
+	p := &sqPayment{
+		ID:          "pay_2",
+		Status:      "COMPLETED",
+		TotalMoney:  sqMoney{Amount: 2500, Currency: "GBP"},
+		CardDetails: nil,
+	}
+
+	result := paymentFromSquare(p)
+	if result.CardBrand != "" {
+		t.Errorf("expected empty CardBrand when no card details, got %s", result.CardBrand)
+	}
+	if result.Amount != 2500 {
+		t.Errorf("expected amount 2500, got %d", result.Amount)
+	}
+}

frontend/src/lib/components/account/UserBookingModal.svelte

@@ -138,6 +138,13 @@ import CardBrandIcon from '$lib/components/payments/CardBrandIcon.svelte';
 	let customTipInput = $state('');
 	let tipProcessing = $state(false);
 
+	// Cached idempotency key: generated once per tip attempt, reused on retry
+	// (so a network-timeout retry dedupes instead of double-charging), cleared on
+	// success. Reset when the tip amount changes so an amount change after a
+	// failed attempt gets a fresh key instead of a false dedup (under-charge).
+	let tipIdempotencyKey = $state('');
+	let tipKeyedAmount = $state(0);
+
 	// Card selection state for tips
 	let tipSavedCards = $state<SavedCard[]>([]);
 	let tipLoadingCards = $state(false);
@@ -205,7 +212,9 @@ import CardBrandIcon from '$lib/components/payments/CardBrandIcon.svelte';
 				return expiryYearMonth < currentYearMonth;
 			})()
 	);
-	const hasTipNewCardInvalidMonth = $derived(/^\d{2}\/\d{2}$/.test(tipNewCardExpiry) && tipNewCardExpiryParts === null);
+	const hasTipNewCardInvalidMonth = $derived(
+		/^\d{2}\/\d{2}$/.test(tipNewCardExpiry) && tipNewCardExpiryParts === null
+	);
 
 	const tipNewCardError = $derived(
 		tipShowNewCard || tipSavedCards.length === 0
@@ -215,13 +224,19 @@ import CardBrandIcon from '$lib/components/payments/CardBrandIcon.svelte';
 					? 'Invalid expiry month'
 					: tipCardExpiryTouched && isTipNewCardExpiryPast
 						? 'This card has expired'
-						: tipCardExpiryTouched && tipNewCardExpiry.length > 0 && !/^\d{2}\/\d{2}$/.test(tipNewCardExpiry)
+						: tipCardExpiryTouched &&
+							  tipNewCardExpiry.length > 0 &&
+							  !/^\d{2}\/\d{2}$/.test(tipNewCardExpiry)
 							? 'Enter expiry as MM/YY'
 							: tipCVCTouched && tipNewCardCVC.length < 3 && tipNewCardCVC.length > 0
 								? 'Enter your CVC number'
-								: isValidLuhn(tipNewCardNumber) && /^\d{2}\/\d{2}$/.test(tipNewCardExpiry) && tipNewCardCVC.length >= 3
+								: isValidLuhn(tipNewCardNumber) &&
+									  /^\d{2}\/\d{2}$/.test(tipNewCardExpiry) &&
+									  tipNewCardCVC.length >= 3
 									? null
-									: tipNewCardNumber.length === 0 && tipNewCardExpiry.length === 0 && tipNewCardCVC.length === 0
+									: tipNewCardNumber.length === 0 &&
+										  tipNewCardExpiry.length === 0 &&
+										  tipNewCardCVC.length === 0
 										? null
 										: 'Please complete all card fields'
 			: null
@@ -312,7 +327,12 @@ import CardBrandIcon from '$lib/components/payments/CardBrandIcon.svelte';
 
 		// Validate card details for new card payments
 		if (tipShowNewCard || tipSavedCards.length === 0) {
-			if (!isValidLuhn(tipNewCardNumber) || !/^\d{2}\/\d{2}$/.test(tipNewCardExpiry) || isTipNewCardExpiryPast || tipNewCardCVC.length < 3) {
+			if (
+				!isValidLuhn(tipNewCardNumber) ||
+				!/^\d{2}\/\d{2}$/.test(tipNewCardExpiry) ||
+				isTipNewCardExpiryPast ||
+				tipNewCardCVC.length < 3
+			) {
 				tipProcessing = false;
 				toast.error(tipNewCardError || 'Please enter valid credit card details');
 				return;
@@ -320,7 +340,14 @@ import CardBrandIcon from '$lib/components/payments/CardBrandIcon.svelte';
 		}
 
 		try {
-			const body: Record<string, unknown> = { amount: Math.round(tipAmount * 100) };
+			if (!tipIdempotencyKey || tipKeyedAmount !== tipAmount) {
+				tipIdempotencyKey = crypto.randomUUID();
+				tipKeyedAmount = tipAmount;
+			}
+			const body: Record<string, unknown> = {
+				amount: Math.round(tipAmount * 100),
+				idempotency_key: tipIdempotencyKey
+			};
 
 			if (tipShowNewCard || tipSavedCards.length === 0) {
 				body.new_card_token = tipNewCardNumber.replace(/\s/g, '');
@@ -339,6 +366,8 @@ import CardBrandIcon from '$lib/components/payments/CardBrandIcon.svelte';
 				throw new Error(errorText || 'Tip payment failed');
 			}
 			toast.success('Thank you for your tip!');
+			tipIdempotencyKey = '';
+			tipKeyedAmount = 0;
 			showTipModal = false;
 			fetchBookingDetails();
 		} catch (err) {
@@ -1173,6 +1202,8 @@ ${hasVAT ? `<p class="warning">VAT is included at ${biz?.default_vat_rate ?? 20}
 			tipAmount = 0;
 			selectedTipPreset = null;
 			customTipInput = '';
+			tipIdempotencyKey = '';
+			tipKeyedAmount = 0;
 		}
 	}}
 >
@@ -1221,7 +1252,9 @@ ${hasVAT ? `<p class="warning">VAT is included at ${biz?.default_vat_rate ?? 20}
 
 			<!-- Card Selection for Tip -->
 			<div class="space-y-3">
-				<span class="block text-xs font-semibold tracking-wider text-gray-500 uppercase">Payment Method</span>
+				<span class="block text-xs font-semibold tracking-wider text-gray-500 uppercase"
+					>Payment Method</span
+				>
 
 				{#if tipLoadingCards}
 					<div class="py-2 text-center text-sm text-gray-500">Loading payment methods...</div>
@@ -1230,8 +1263,14 @@ ${hasVAT ? `<p class="warning">VAT is included at ${biz?.default_vat_rate ?? 20}
 						{#each tipSavedCards as card (card.id)}
 							<button
 								type="button"
-								class="flex w-full items-center justify-between rounded-lg border p-3 text-left {tipSelectedCardId === card.id && !tipShowNewCard ? 'border-input bg-accent' : 'border-gray-200 hover:bg-gray-50'}"
-								onclick={() => { tipSelectedCardId = card.id; tipShowNewCard = false; }}
+								class="flex w-full items-center justify-between rounded-lg border p-3 text-left {tipSelectedCardId ===
+									card.id && !tipShowNewCard
+									? 'border-input bg-accent'
+									: 'border-gray-200 hover:bg-gray-50'}"
+								onclick={() => {
+									tipSelectedCardId = card.id;
+									tipShowNewCard = false;
+								}}
 							>
 								<div class="flex items-center gap-3">
 									<CardBrandIcon brand={card.brand} />
@@ -1249,8 +1288,13 @@ ${hasVAT ? `<p class="warning">VAT is included at ${biz?.default_vat_rate ?? 20}
 						{/each}
 						<button
 							type="button"
-							class="flex w-full items-center justify-between rounded-lg border p-3 text-left {tipShowNewCard ? 'border-input bg-accent' : 'border-gray-200 hover:bg-gray-50'}"
-							onclick={() => { tipSelectedCardId = null; tipShowNewCard = true; }}
+							class="flex w-full items-center justify-between rounded-lg border p-3 text-left {tipShowNewCard
+								? 'border-input bg-accent'
+								: 'border-gray-200 hover:bg-gray-50'}"
+							onclick={() => {
+								tipSelectedCardId = null;
+								tipShowNewCard = true;
+							}}
 						>
 							<div class="flex items-center gap-3">
 								<div

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

@@ -694,7 +694,7 @@
 				amount: Number(topUpAmount),
 				payment_method: 'on_the_house',
 				gift_card_id: gcId,
-				idempotency_key: 'till-on-the-house-' + gcId + '-' + Date.now()
+				idempotency_key: getIdempotencyKey()
 			};
 
 			const res = await apiFetch('/api/admin/till/sale', {

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

@@ -376,10 +376,10 @@
 
 	// Check for conflicts whenever weekStarts, hours, or rescheduleVersion change
 	$effect(() => {
-		// Track these reactive values so the effect re-runs when they change
+		// Read these reactive values so the effect re-runs when they change
 		const weekStarts = exceptionDraft.weekStarts;
-		const hours = exceptionDraft.hours;
-		const rv = rescheduleVersion;
+		void exceptionDraft.hours;
+		void rescheduleVersion;
 		// Avoid triggering check on initial empty state
 		if (weekStarts.length > 0 && showExceptionModal) {
 			checkConflictingBookings();
@@ -747,7 +747,12 @@
 							? ''
 							: 's'} with the proposed hours
 					</span>
-					<Button variant="outline" size="sm" class="h-6 text-xs ml-auto" onclick={checkConflictingBookings}>
+					<Button
+						variant="outline"
+						size="sm"
+						class="h-6 text-xs ml-auto"
+						onclick={checkConflictingBookings}
+					>
 						Refresh
 					</Button>
 				</div>

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

@@ -1,4 +1,5 @@
 <script lang="ts">
+	import { SvelteDate } from 'svelte/reactivity';
 	import { toast } from 'svelte-sonner';
 	import { extractErrorMessage } from '$lib/utils/toast-safe';
 	import { browser } from '$app/environment';
@@ -57,15 +58,9 @@
 			  };
 		openUserModal?: (userId: string) => void;
 		openBookingModal?: (bookingId: string) => void;
-		rescheduleVersion?: number;
 	}
 
-	let {
-		defaultHours: defaultHoursProp,
-		openUserModal,
-		openBookingModal,
-		rescheduleVersion = 0
-	}: Props = $props();
+	let { defaultHours: defaultHoursProp, openUserModal, openBookingModal }: Props = $props();
 
 	// =============== State ===============
 	let defaultHours = $state<WorkingHourRow[]>([]);
@@ -201,46 +196,6 @@
 	}
 
 	/** Saves the default hours draft after confirmation. */
-	async function confirmSaveDefaultHours() {
-		savingHours = true;
-		const loadingToast = toast.loading('Saving default hours...');
-
-		try {
-			// Map snake_case to camelCase for API
-			const payload = defaultHoursDraft.map((hour) => ({
-				weekday: hour.weekday,
-				startTime: hour.start_time,
-				endTime: hour.end_time,
-				isOpen: hour.is_open
-			}));
-
-			const response = await apiFetch('/api/scheduling/default-hours', {
-				method: 'PUT',
-				headers: {
-					'Content-Type': 'application/json'
-				},
-				body: JSON.stringify(payload)
-			});
-
-			if (response.ok) {
-				// Update the main state from the draft state if successful
-				defaultHours = JSON.parse(JSON.stringify(defaultHoursDraft));
-				showDefaultHoursModal = false;
-				toast.success('Default hours saved successfully!', { id: loadingToast });
-			} else if (response.status === 401 || response.status === 403) {
-				toast.error('Unauthorized. Please log in again.', { id: loadingToast });
-			} else {
-				const text = await response.text();
-				toast.error('Failed to save: ' + extractErrorMessage(text), { id: loadingToast });
-			}
-		} catch (err) {
-			console.error('save default hours', err);
-			toast.error('Network error saving hours', { id: loadingToast });
-		} finally {
-			savingHours = false;
-		}
-	}
-
 	async function checkConflictingBookings() {
 		const proposedHours = defaultHoursDraft.map((h) => ({
 			weekday: h.weekday,
@@ -274,7 +229,7 @@
 	}
 
 	function getDefaultEffectiveDate(): string {
-		const d = new Date();
+		const d = new SvelteDate();
 		d.setDate(d.getDate() + 1);
 		return d.toISOString().slice(0, 10);
 	}
@@ -394,8 +349,8 @@
 	// Trigger conflict check when the modal opens or hours/date change
 	$effect(() => {
 		const open = showDefaultHoursModal;
-		const hours = defaultHoursDraft;
-		const date = effectiveDate;
+		void defaultHoursDraft;
+		void effectiveDate;
 		if (open) {
 			checkConflictingBookings();
 		}
@@ -922,7 +877,12 @@
 									? ''
 									: 's'}
 							</span>
-							<Button variant="outline" size="sm" class="h-6 text-xs ml-auto" onclick={checkConflictingBookings}>
+							<Button
+								variant="outline"
+								size="sm"
+								class="h-6 text-xs ml-auto"
+								onclick={checkConflictingBookings}
+							>
 								Refresh
 							</Button>
 						</div>

frontend/src/lib/components/layout/BusinessHours.svelte

@@ -1,4 +1,5 @@
 <script lang="ts">
+	import { SvelteDate } from 'svelte/reactivity';
 	import { onMount, onDestroy } from 'svelte';
 	import { formatTime } from '$lib/utils/timeSlots';
 
@@ -57,7 +58,10 @@
 					// may include microsecond precision ("17:00:00.000000") from
 					// PostgreSQL's ::text cast, while staged hours are plain "17:00".
 					const norm = (t: string) => t.replace(/\.\d+$/, '').replace(/^(\d{2}:\d{2}).*$/, '$1');
-					return norm(h.startTime) !== norm(current.startTime) || norm(h.endTime) !== norm(current.endTime);
+					return (
+						norm(h.startTime) !== norm(current.startTime) ||
+						norm(h.endTime) !== norm(current.endTime)
+					);
 				})
 			: []
 	);
@@ -77,7 +81,7 @@
 		const today = getLondonDate();
 		const dayOfWeek = today.getDay(); // 0=Sun
 		const offset = dayOfWeek === 0 ? -6 : 1 - dayOfWeek;
-		const monday = new Date(today);
+		const monday = new SvelteDate(today);
 		monday.setDate(today.getDate() + offset);
 		return fmtDate(monday);
 	}
@@ -254,7 +258,7 @@
 
 		{#if loading}
 			<div class="animate-pulse space-y-3">
-				{#each { length: 7 } as _}
+				{#each Array.from({ length: 7 }) as _, i (i)}
 					<div class="flex justify-between">
 						<div class="h-4 w-20 rounded bg-gray-200"></div>
 						<div class="h-4 w-24 rounded bg-gray-200"></div>
@@ -308,7 +312,9 @@
 			{#if scheduledChange && scheduledChangeDays.length > 0}
 				<hr class="my-2 border-gray-200" />
 				<p class="mb-2 text-center text-xs font-medium text-amber-600">
-					{scheduledChangeDays.length === 7 ? 'Opening hours will change from' : 'These opening hours will change from'}
+					{scheduledChangeDays.length === 7
+						? 'Opening hours will change from'
+						: 'These opening hours will change from'}
 					{new Date(scheduledChange.effective_date + 'T00:00:00').toLocaleDateString('en-GB', {
 						day: 'numeric',
 						month: 'short',

frontend/src/lib/components/payments/CardBrandIcon.svelte

@@ -31,9 +31,16 @@
 </script>
 
 {#if showSvg}
-	<div class="flex h-8 min-w-12 items-center justify-center rounded" role="img" aria-label={brand}>{@html normalizedSvg}</div>
+	<div class="flex h-8 min-w-12 items-center justify-center rounded" role="img" aria-label={brand}>
+		<!-- eslint-disable-next-line svelte/no-at-html-tags -- SVG strings are hardcoded constants, never user input -->
+		{@html normalizedSvg}
+	</div>
 {:else}
-	<div class="flex h-8 min-w-12 items-center justify-center rounded bg-gray-100 px-2 text-xs font-medium text-gray-700 uppercase" role="img" aria-label={brand}>
+	<div
+		class="flex h-8 min-w-12 items-center justify-center rounded bg-gray-100 px-2 text-xs font-medium text-gray-700 uppercase"
+		role="img"
+		aria-label={brand}
+	>
 		{brand}
 	</div>
 {/if}

frontend/src/routes/admin/+page.svelte

@@ -380,7 +380,7 @@
 				<div class="space-y-4 p-4">
 					<TimeBlockers {openUserModal} {openBookingModal} {rescheduleVersion} {defaultHours} />
 					<HolidayHours {openUserModal} {openBookingModal} {rescheduleVersion} />
-					<WeeklySchedule {defaultHours} {openUserModal} {openBookingModal} {rescheduleVersion} />
+					<WeeklySchedule {defaultHours} {openUserModal} {openBookingModal} />
 				</div>
 			{/if}
 		</div>

frontend/src/routes/pay-tip/[id]/+page.svelte

@@ -41,11 +41,17 @@ import CardBrandIcon from '$lib/components/payments/CardBrandIcon.svelte';
 	let loading = $state(true);
 	let error = $state<string | null>(null);
 	let paymentState = $state<'idle' | 'processing' | 'success' | 'error'>('idle');
+
+	// Cached idempotency key: generated once per payment attempt, reused on retry
+	// (so a network-timeout retry dedupes instead of double-charging), cleared on
+	// success. Reset when the tip amount changes so an amount change after a
+	// failed attempt gets a fresh key instead of a false dedup (under-charge).
+	let tipIdempotencyKey = $state('');
+	let tipKeyedAmount = $state(0);
 	let pageState = $state<'loading' | 'authorized' | 'unauthorized' | 'admin'>('loading');
 
 	// Card selection state
 	let savedCards = $state<SavedCard[]>([]);
-	let loadingCards = $state(false);
 	let selectedCardId = $state<string | null>(null);
 	let showNewCardForm = $state(false);
 
@@ -118,7 +124,9 @@ import CardBrandIcon from '$lib/components/payments/CardBrandIcon.svelte';
 				return expiryYearMonth < currentYearMonth;
 			})()
 	);
-	const hasNewCardInvalidMonth = $derived(/^\d{2}\/\d{2}$/.test(newCardExpiry) && newCardExpiryParts === null);
+	const hasNewCardInvalidMonth = $derived(
+		/^\d{2}\/\d{2}$/.test(newCardExpiry) && newCardExpiryParts === null
+	);
 
 	const newCardError = $derived(
 		showNewCardForm || savedCards.length === 0
@@ -132,9 +140,13 @@ import CardBrandIcon from '$lib/components/payments/CardBrandIcon.svelte';
 							? 'Enter expiry as MM/YY'
 							: cardCVCTouched && newCardCVC.length < 3 && newCardCVC.length > 0
 								? 'Enter your CVC number'
-								: isValidLuhn(newCardNumber) && /^\d{2}\/\d{2}$/.test(newCardExpiry) && newCardCVC.length >= 3
+								: isValidLuhn(newCardNumber) &&
+									  /^\d{2}\/\d{2}$/.test(newCardExpiry) &&
+									  newCardCVC.length >= 3
 									? null
-									: newCardNumber.length === 0 && newCardExpiry.length === 0 && newCardCVC.length === 0
+									: newCardNumber.length === 0 &&
+										  newCardExpiry.length === 0 &&
+										  newCardCVC.length === 0
 										? null
 										: 'Please complete all card fields'
 			: null
@@ -232,21 +244,18 @@ import CardBrandIcon from '$lib/components/payments/CardBrandIcon.svelte';
 		if (savedCardsStore.loaded) {
 			savedCards = savedCardsStore.cards;
 			if (savedCards.length > 0 && !selectedCardId) {
-				selectedCardId = savedCards.find(c => c.is_default)?.id || savedCards[0].id;
+				selectedCardId = savedCards.find((c) => c.is_default)?.id || savedCards[0].id;
 			}
 			return;
 		}
-		loadingCards = true;
 		try {
 			await savedCardsStore.fetch();
 			savedCards = savedCardsStore.cards;
 			if (savedCards.length > 0 && !selectedCardId) {
-				selectedCardId = savedCards.find(c => c.is_default)?.id || savedCards[0].id;
+				selectedCardId = savedCards.find((c) => c.is_default)?.id || savedCards[0].id;
 			}
 		} catch {
 			// ignore
-		} finally {
-			loadingCards = false;
 		}
 	}
 
@@ -295,7 +304,12 @@ import CardBrandIcon from '$lib/components/payments/CardBrandIcon.svelte';
 
 		// Validate card details for new card payments
 		if (showNewCardForm || savedCards.length === 0) {
-			if (!isValidLuhn(newCardNumber) || !/^\d{2}\/\d{2}$/.test(newCardExpiry) || isNewCardExpiryPast || newCardCVC.length < 3) {
+			if (
+				!isValidLuhn(newCardNumber) ||
+				!/^\d{2}\/\d{2}$/.test(newCardExpiry) ||
+				isNewCardExpiryPast ||
+				newCardCVC.length < 3
+			) {
 				paymentState = 'idle';
 				toast.error(newCardError || 'Please enter valid credit card details');
 				return;
@@ -303,8 +317,15 @@ import CardBrandIcon from '$lib/components/payments/CardBrandIcon.svelte';
 		}
 
 		try {
+			if (!tipIdempotencyKey || tipKeyedAmount !== tipAmount) {
+				tipIdempotencyKey = crypto.randomUUID();
+				tipKeyedAmount = tipAmount;
+			}
 			const amountInPence = Math.round(tipAmount * 100);
-			const body: Record<string, unknown> = { amount: amountInPence };
+			const body: Record<string, unknown> = {
+				amount: amountInPence,
+				idempotency_key: tipIdempotencyKey
+			};
 
 			if (showNewCardForm || savedCards.length === 0) {
 				body.new_card_token = newCardNumber.replace(/\s/g, '');
@@ -325,6 +346,8 @@ import CardBrandIcon from '$lib/components/payments/CardBrandIcon.svelte';
 			}
 
 			paymentState = 'success';
+			tipIdempotencyKey = '';
+			tipKeyedAmount = 0;
 			toast.success('Thank you for your tip!');
 		} catch (err) {
 			paymentState = 'error';
@@ -542,16 +565,15 @@ import CardBrandIcon from '$lib/components/payments/CardBrandIcon.svelte';
 				<Card.Content>
 					{#if savedCards.length > 0}
 						<div class="space-y-3">
-							<span
-								class="block text-xs font-semibold tracking-wider text-gray-500 uppercase"
-							>
+							<span class="block text-xs font-semibold tracking-wider text-gray-500 uppercase">
 								Payment Method
 							</span>
 							<div class="space-y-2">
 								{#each savedCards as card (card.id)}
 									<button
 										type="button"
-										class="flex w-full items-center justify-between rounded-lg border p-3 text-left {selectedCardId === card.id && !showNewCardForm
+										class="flex w-full items-center justify-between rounded-lg border p-3 text-left {selectedCardId ===
+											card.id && !showNewCardForm
 											? 'border-input bg-accent'
 											: 'border-gray-200 hover:bg-gray-50'}"
 										onclick={() => {

frontend/src/routes/tip/+page.svelte

@@ -49,9 +49,15 @@ import CardBrandIcon from '$lib/components/payments/CardBrandIcon.svelte';
 	let booking = $state<Booking | null>(null);
 	let paymentState = $state<'idle' | 'processing' | 'success' | 'error'>('idle');
 
+	// Cached idempotency key: generated once per payment attempt, reused on retry
+	// (so a network-timeout retry dedupes instead of double-charging), cleared on
+	// success. Reset when the tip amount changes so an amount change after a
+	// failed attempt gets a fresh key instead of a false dedup (under-charge).
+	let tipIdempotencyKey = $state('');
+	let tipKeyedAmount = $state(0);
+
 	// Card selection state (same pattern as UserPaymentModal)
 	let savedCards = $state<SavedCard[]>([]);
-	let loadingCards = $state(false);
 	let selectedCardId = $state<string | null>(null);
 	let showNewCardForm = $state(false);
 
@@ -144,7 +150,9 @@ import CardBrandIcon from '$lib/components/payments/CardBrandIcon.svelte';
 				return expiryYearMonth < currentYearMonth;
 			})()
 	);
-	const hasNewCardInvalidMonth = $derived(/^\d{2}\/\d{2}$/.test(newCardExpiry) && newCardExpiryParts === null);
+	const hasNewCardInvalidMonth = $derived(
+		/^\d{2}\/\d{2}$/.test(newCardExpiry) && newCardExpiryParts === null
+	);
 
 	const newCardError = $derived(
 		showNewCardForm || savedCards.length === 0
@@ -158,9 +166,13 @@ import CardBrandIcon from '$lib/components/payments/CardBrandIcon.svelte';
 							? 'Enter expiry as MM/YY'
 							: cardCVCTouched && newCardCVC.length < 3 && newCardCVC.length > 0
 								? 'Enter your CVC number'
-								: isValidLuhn(newCardNumber) && /^\d{2}\/\d{2}$/.test(newCardExpiry) && newCardCVC.length >= 3
+								: isValidLuhn(newCardNumber) &&
+									  /^\d{2}\/\d{2}$/.test(newCardExpiry) &&
+									  newCardCVC.length >= 3
 									? null
-									: newCardNumber.length === 0 && newCardExpiry.length === 0 && newCardCVC.length === 0
+									: newCardNumber.length === 0 &&
+										  newCardExpiry.length === 0 &&
+										  newCardCVC.length === 0
 										? null
 										: 'Please complete all card fields'
 			: null
@@ -244,7 +256,12 @@ import CardBrandIcon from '$lib/components/payments/CardBrandIcon.svelte';
 
 		// Validate card details for new card payments
 		if (showNewCardForm || savedCards.length === 0) {
-			if (!isValidLuhn(newCardNumber) || !/^\d{2}\/\d{2}$/.test(newCardExpiry) || isNewCardExpiryPast || newCardCVC.length < 3) {
+			if (
+				!isValidLuhn(newCardNumber) ||
+				!/^\d{2}\/\d{2}$/.test(newCardExpiry) ||
+				isNewCardExpiryPast ||
+				newCardCVC.length < 3
+			) {
 				paymentState = 'idle';
 				toast.error(newCardError || 'Please enter valid credit card details');
 				return;
@@ -252,8 +269,15 @@ import CardBrandIcon from '$lib/components/payments/CardBrandIcon.svelte';
 		}
 
 		try {
+			if (!tipIdempotencyKey || tipKeyedAmount !== tipAmount) {
+				tipIdempotencyKey = crypto.randomUUID();
+				tipKeyedAmount = tipAmount;
+			}
 			const amountInPence = Math.round(tipAmount * 100);
-			const body: Record<string, unknown> = { amount: amountInPence };
+			const body: Record<string, unknown> = {
+				amount: amountInPence,
+				idempotency_key: tipIdempotencyKey
+			};
 
 			if (showNewCardForm || savedCards.length === 0) {
 				body.new_card_token = newCardNumber.replace(/\s/g, '');
@@ -274,6 +298,8 @@ import CardBrandIcon from '$lib/components/payments/CardBrandIcon.svelte';
 			}
 
 			paymentState = 'success';
+			tipIdempotencyKey = '';
+			tipKeyedAmount = 0;
 			toast.success('Thank you for your tip!');
 		} catch (err) {
 			paymentState = 'error';
@@ -367,21 +393,18 @@ import CardBrandIcon from '$lib/components/payments/CardBrandIcon.svelte';
 		if (savedCardsStore.loaded) {
 			savedCards = savedCardsStore.cards;
 			if (savedCards.length > 0 && !selectedCardId) {
-				selectedCardId = savedCards.find(c => c.is_default)?.id || savedCards[0].id;
+				selectedCardId = savedCards.find((c) => c.is_default)?.id || savedCards[0].id;
 			}
 			return;
 		}
-		loadingCards = true;
 		try {
 			await savedCardsStore.fetch();
 			savedCards = savedCardsStore.cards;
 			if (savedCards.length > 0 && !selectedCardId) {
-				selectedCardId = savedCards.find(c => c.is_default)?.id || savedCards[0].id;
+				selectedCardId = savedCards.find((c) => c.is_default)?.id || savedCards[0].id;
 			}
 		} catch {
 			// ignore — user can enter new card
-		} finally {
-			loadingCards = false;
 		}
 	}
 </script>
@@ -561,23 +584,31 @@ import CardBrandIcon from '$lib/components/payments/CardBrandIcon.svelte';
 			<Card.Root class="mb-6">
 				<Card.Content class="space-y-4">
 					<div class="space-y-3">
-						<span class="block text-xs font-semibold tracking-wider text-gray-500 uppercase">Payment Method</span>
+						<span class="block text-xs font-semibold tracking-wider text-gray-500 uppercase"
+							>Payment Method</span
+						>
 
 						{#if savedCards.length > 0}
 							<div class="space-y-2">
 								{#each savedCards as card (card.id)}
 									<button
 										type="button"
-										class="flex w-full items-center justify-between rounded-lg border p-3 text-left {selectedCardId === card.id && !showNewCardForm
+										class="flex w-full items-center justify-between rounded-lg border p-3 text-left {selectedCardId ===
+											card.id && !showNewCardForm
 											? 'border-input bg-accent'
 											: 'border-gray-200 hover:bg-gray-50'}"
-										onclick={() => { selectedCardId = card.id; showNewCardForm = false; }}
+										onclick={() => {
+											selectedCardId = card.id;
+											showNewCardForm = false;
+										}}
 									>
 										<div class="flex items-center gap-3">
 											<CardBrandIcon brand={card.brand} />
 											<div class="text-sm">
 												<span class="font-mono">**** {card.last_4}</span>
-												<span class="ml-2 text-xs text-gray-400">Exp {String(card.exp_month).padStart(2, '0')}/{card.exp_year}</span>
+												<span class="ml-2 text-xs text-gray-400"
+													>Exp {String(card.exp_month).padStart(2, '0')}/{card.exp_year}</span
+												>
 											</div>
 										</div>
 										{#if selectedCardId === card.id && !showNewCardForm}
@@ -591,7 +622,10 @@ import CardBrandIcon from '$lib/components/payments/CardBrandIcon.svelte';
 									class="flex w-full items-center justify-between rounded-lg border p-3 text-left {showNewCardForm
 										? 'border-input bg-accent'
 										: 'border-gray-200 hover:bg-gray-50'}"
-									onclick={() => { selectedCardId = null; showNewCardForm = true; }}
+									onclick={() => {
+										selectedCardId = null;
+										showNewCardForm = true;
+									}}
 								>
 									<div class="flex items-center gap-3">
 										<div
@@ -599,7 +633,9 @@ import CardBrandIcon from '$lib/components/payments/CardBrandIcon.svelte';
 										>
 											NEW
 										</div>
-										<span class="animate-pulse text-sm font-medium text-gray-700">Use a new card</span>
+										<span class="animate-pulse text-sm font-medium text-gray-700"
+											>Use a new card</span
+										>
 									</div>
 									{#if showNewCardForm}
 										<span class="text-xs font-semibold text-primary">Selected</span>