Fix silent tip/gift-card money loss on pending retry; terminal checkout wire; sentinel error; docs

CRITICAL — same-amount tip retry silently never charged:
- CreateTipPayment idempotency check now only short-circuits when the
  existing record is 'completed'. A 'pending' record (previous Square call
  failed) is REUSED and the charge re-attempted with the same key (Square
  dedups safely), instead of returning the stale pending record as 200 with
  a success toast and no charge.
- Same fix in BuyGiftCard: pending records trigger a re-attempt, not a
  false-success response. Unique idempotency_key constraint means the
  pending record must be reused, not re-inserted.
- Fixes the savepoint/rollback interaction: the nested tx (savepoint) is
  now committed in the reuse path so the deferred rollback doesn't undo the
  later status UPDATE on the same connection.
- Regression test: TestTipPayment_RetryPending_ReattemptsCharge verifies a
  pending record + same-key retry re-attempts and completes, reusing the
  record (count stays 1).

MAJOR — terminal checkout wire contract:
- device_id now sent as checkout.device_options.device_id (Square's required
  shape), not a top-level field which Square rejects with 400.
- 'checkout pending' detection now uses typed sentinel ErrCheckoutPending
  with errors.Is in both handlers, matching mock and real HTTP client.

MAJOR — exp_month/exp_year omitted from card creation payload when unset
(now *int with omitempty) — Square would 400 on 0/0; expiry comes from the
tokenized source.

Docs:
- README payments/infrastructure sections corrected (Web Payments SDK claim
  replaced with accurate P11-backlog note; dev mock parity described)
- Future Work P11 updated to reflect raw-PAN rejection is now enforced in
  both mock and prod (new-card flows are a documented dead end)
- Added plans/p11-square-web-payments-sdk.md: full implementation plan +
  handoff prompt for the agent picking up P11 (Web Payments SDK nonces)

README.md

@@ -6,7 +6,7 @@ Nail salon booking platform — Go 1.26.5 backend + SvelteKit 5 SPA + PostgreSQL
 
 **Booking**: Self-service (customer), walk-in (admin), call-in (admin). Slot reservations prevent double-booking (4 TTL types). **Self-blocking prevention**: `excludeUserID` parameter filters a user's own `RESERVATION` entries from time blocker overlap checks, allowing re-reservation and booking at overlapping slots. **Explicit cancellation**: `DELETE /api/bookings/reserve` releases a user reservation; `DELETE /api/admin/bookings/reserve` releases an admin walk-in/call-in reservation. **Background cleanup**: Centralised cron scheduler (`backend/internal/jobs/`) runs 21 maintenance jobs: reservation/deposit cleanup every 5min, hourly campaign transitions, daily unpaid-booking notifications, staged default hours auto-apply, GDPR anonymization, financial aggregation, and token/code cleanup. Guest accounts with GDPR-compliant anonymization (including `RESERVATION:edit_request:%` scrubbing). Service eligibility based on age + patch test validity. Overlap checks use `FOR UPDATE` row locks inside transactions. Closing-hours validation (`closing_time.go`) resolves both current and staged default hours.
 
-**Payments**: Square Terminal (in-person) + Web Payments SDK (online). Cash with change calculation. Gift cards (12-digit code or account balance). Saved cards for faster checkout. Tips on completed bookings. Refunds with notice-period tiers and deposit protection (72h/24h thresholds). All payment types: deposit, full, partial, balance, tip. Payment >20% of total promotes `pending_release` bookings back to `confirmed`. Deposit paid is computed from payments on-the-fly. The first 50% of each payment is always carved out as deposit (via `buildSplitRecords`); any overflow beyond the booking total becomes a tip. A PostgreSQL `pg_advisory_lock` serializes payment attempts per-booking to prevent two-tab double-payment races. Gift card purchases now insert a pending payment record with VAT before calling Square — the DB transaction commits first, so Square failures leave a retryable pending record.
+**Payments**: Square Terminal (in-person, via `CreateTerminalCheckout`) + online card payments (currently raw-PAN entry in dev only; production nonce integration is backlog item P11 — see `obsidian/Crussell/Future Work - Gap Backlog.md`). Cash with change calculation. Gift cards (12-digit code or account balance). Saved cards for faster checkout. Tips on completed bookings. Refunds with notice-period tiers and deposit protection (72h/24h thresholds). All payment types: deposit, full, partial, balance, tip. Payment >20% of total promotes `pending_release` bookings back to `confirmed`. Deposit paid is computed from payments on-the-fly. The first 50% of each payment is always carved out as deposit (via `buildSplitRecords`); any overflow beyond the booking total becomes a tip. A PostgreSQL `pg_advisory_lock` serializes payment attempts per-booking to prevent two-tab double-payment races. Gift card purchases insert a pending payment record with VAT before calling Square — the DB transaction commits first, so Square failures leave a retryable pending record (same-key retries reuse it).
 
 **Gift Cards**: Multi-method purchase (cash, card machine, online card, giveaway). Inventory cards for stock management. 24-month rolling expiry. Idle account cleanup (2yr/5yr thresholds). Expired balance recovery with admin audit trail. Transaction audit log. Idempotency keys for purchases.
 
@@ -22,7 +22,7 @@ Nail salon booking platform — Go 1.26.5 backend + SvelteKit 5 SPA + PostgreSQL
 
 **Frontend**: Portfolio gallery with fuzzy tag search (relevance-sorted) and exact category filters (date-sorted), multi-format images (AVIF/WebP/JPEG/JXL with WASM client-side encoding), cursor-based pagination. MapLibre GL map on contact page. PhoneInput component with UK validation. CharCounter for long notes.
 
-**Infrastructure**: Docker Compose (postgres, backend, sabredav, nginx). Dev mock for Square payments (`//go:build dev`). RustFS dev storage, Cloudflare R2 for prod. SabreDAV CardDAV sync for profile photos.
+**Infrastructure**: Docker Compose (postgres, backend, sabredav, nginx). Dev mock for Square payments (`//go:build dev`) that mirrors production PCI-DSS behaviour (rejects raw PANs; accepts `cnon:`/`ccof:` tokens only). RustFS dev storage, Cloudflare R2 for prod. SabreDAV CardDAV sync for profile photos.
 
 **Middleware**: `JsonContentType` sets `Content-Type: application/json` globally, replacing ~80+ individual `w.Header().Set()` calls. `RespondJSON`/`RespondError` helpers standardise API response format. Progressive rate limiting (dual-window) on login/register with account lockout.
 

backend/handlers/payments/giftcards.go

@@ -891,16 +891,27 @@ func BuyGiftCard(w http.ResponseWriter, r *http.Request) {
 
 	paymentService := NewPaymentService()
 
+	// Idempotency: only short-circuit when the existing record is 'completed'.
+	// A 'pending' record means the previous Square call failed — returning it
+	// as 200 would show a success without ever charging. Re-attempt below with
+	// the same key (Square dedups safely) and reuse the pending record.
+	reusePendingID := ""
 	if req.IdempotencyKey != "" {
 		existing, err := paymentService.CheckIdempotencyByKey(ctx, req.IdempotencyKey)
 		if err != nil {
 			log.Printf("Failed to check idempotency: %v", err)
 		}
 		if existing != nil {
-			if err := json.NewEncoder(w).Encode(existing); err != nil {
+			if existing.Status == "completed" {
-				log.Printf("Failed to encode JSON response: %v", err)
+				if err := json.NewEncoder(w).Encode(existing); err != nil {
+					log.Printf("Failed to encode JSON response: %v", err)
+				}
+				return
+			}
+			if existing.Status == "pending" {
+				reusePendingID = existing.ID
+				log.Printf("[PAYMENTS] Reusing pending payment %s for idempotent gift-card retry (key %s)", existing.ID, req.IdempotencyKey)
 			}
-			return
 		}
 	}
 
@@ -958,43 +969,62 @@ func BuyGiftCard(w http.ResponseWriter, r *http.Request) {
 	}()
 
 	var buyPaymentID string
-	fees := paymentService.CalculateFees(req.Amount, "online")
+	if reusePendingID != "" {
-	record := PaymentRecord{
+		// Reusing the pending record from a failed prior attempt — do not
-		PaymentType:     "full",
+		// insert a duplicate (idempotency_key is UNIQUE). Proceed straight to
-		PaymentMethod:   "online_square",
+		// the Square call, which dedups on the same key.
-		Status:          "pending",
+		buyPaymentID = reusePendingID
-		Amount:          amountPounds,
+	} else {
-		SquarePaymentID: nil,
+		fees := paymentService.CalculateFees(req.Amount, "online")
-		IdempotencyKey:  &req.IdempotencyKey,
+		record := PaymentRecord{
-		Fees:            float64(fees) / 100.0,
+			PaymentType:     "full",
-		UserSavedCardID: savedCardID,
+			PaymentMethod:   "online_square",
-		CreatedAt:       clock.Now(),
+			Status:          "pending",
-		UpdatedAt:       clock.Now(),
+			Amount:          amountPounds,
-		CreatedBy:       &userID,
+			SquarePaymentID: nil,
-	}
+			IdempotencyKey:  &req.IdempotencyKey,
-	err = tx.QueryRow(ctx, `
+			Fees:            float64(fees) / 100.0,
-		INSERT INTO payments (payment_type, payment_method, status, amount, square_payment_id, idempotency_key, fees, user_saved_card_id, created_by, created_at, updated_at)
+			UserSavedCardID: savedCardID,
-		VALUES ($1, $2, $3, $4, $5, $6, $7, $8, $9, $10, $11)
+			CreatedAt:       clock.Now(),
-		RETURNING id
+			UpdatedAt:       clock.Now(),
-	`, record.PaymentType, record.PaymentMethod, record.Status, record.Amount, record.SquarePaymentID, record.IdempotencyKey, record.Fees, record.UserSavedCardID, record.CreatedBy, record.CreatedAt, record.UpdatedAt).Scan(&buyPaymentID)
+			CreatedBy:       &userID,
-	if err != nil {
+		}
-		log.Printf("Failed to insert payment record: %v", err)
+		err = tx.QueryRow(ctx, `
-		http.Error(w, "internal server error", http.StatusInternalServerError)
+			INSERT INTO payments (payment_type, payment_method, status, amount, square_payment_id, idempotency_key, fees, user_saved_card_id, created_by, created_at, updated_at)
-		return
+			VALUES ($1, $2, $3, $4, $5, $6, $7, $8, $9, $10, $11)
-	}
+			RETURNING id
+		`, record.PaymentType, record.PaymentMethod, record.Status, record.Amount, record.SquarePaymentID, record.IdempotencyKey, record.Fees, record.UserSavedCardID, record.CreatedBy, record.CreatedAt, record.UpdatedAt).Scan(&buyPaymentID)
+		if err != nil {
+			log.Printf("Failed to insert payment record: %v", err)
+			http.Error(w, "internal server error", http.StatusInternalServerError)
+			return
+		}
 
-	// Apply VAT to the pending payment
+		// Apply VAT to the pending payment
-	vatCfg, vatErr := GetVATConfig(ctx, tx)
+		vatCfg, vatErr := GetVATConfig(ctx, tx)
-	if vatErr == nil && vatCfg.IsVATRegistered && vatCfg.VoucherType == "SPV" {
+		if vatErr == nil && vatCfg.IsVATRegistered && vatCfg.VoucherType == "SPV" {
-		if _, vatExecErr := tx.Exec(ctx, "SELECT apply_vat_to_payment($1, $2)", buyPaymentID, vatCfg.DefaultVATRate); vatExecErr != nil {
+			if _, vatExecErr := tx.Exec(ctx, "SELECT apply_vat_to_payment($1, $2)", buyPaymentID, vatCfg.DefaultVATRate); vatExecErr != nil {
-			log.Printf("Failed to apply VAT to buy gift card payment %s: %v", buyPaymentID, vatExecErr)
+				log.Printf("Failed to apply VAT to buy gift card payment %s: %v", buyPaymentID, vatExecErr)
+			}
+		}
+
+		if err := tx.Commit(ctx); err != nil {
+			log.Printf("Failed to commit buy transaction: %v", err)
+			http.Error(w, "internal server error", http.StatusInternalServerError)
+			return
 		}
 	}
 
-	if err := tx.Commit(ctx); err != nil {
+	// Commit the (nested/savepoint) transaction in the reuse path too. It is
-		log.Printf("Failed to commit buy transaction: %v", err)
+	// empty, but committing releases the savepoint so the deferred rollback
-		http.Error(w, "internal server error", http.StatusInternalServerError)
+	// becomes a no-op — otherwise that rollback would undo the status UPDATE
-		return
+	// executed later on the same connection.
+	if reusePendingID != "" {
+		if err := tx.Commit(ctx); err != nil {
+			log.Printf("Failed to commit buy transaction (reuse): %v", err)
+			http.Error(w, "internal server error", http.StatusInternalServerError)
+			return
+		}
 	}
 
 	// Step 2: DB transaction committed — safe to call Square now.

backend/handlers/payments/handlers.go

@@ -626,7 +626,7 @@ func GetCheckoutStatus(w http.ResponseWriter, r *http.Request) {
 
 	paymentResult, err := SquareClient.GetCheckout(r.Context(), checkoutID)
 	if err != nil {
-		if err.Error() == "checkout pending" {
+		if errors.Is(err, square.ErrCheckoutPending) {
 			if err := json.NewEncoder(w).Encode(PaymentStatusResponse{Status: "PENDING"}); err != nil {
 				log.Printf("Failed to encode JSON response: %v", err)
 			}
@@ -1900,18 +1900,30 @@ func CreateTipPayment(w http.ResponseWriter, r *http.Request) {
 		}
 	}()
 
-	// Check idempotency inside the transaction — same pattern as CreateBookingPayment.
+	// Check idempotency inside the transaction.
+	// Only short-circuit when the existing record is 'completed'. A 'pending'
+	// record means the previous Square call failed — returning it as 200 would
+	// show a success toast without ever charging. Re-attempt the charge below
+	// with the same idempotency key (Square dedups safely) and reuse the
+	// existing record.
 	var existingID sql.NullString
 	var existingBookingID sql.NullString
 	var existingPaymentType sql.NullString
 	var existingStatus sql.NullString
 	var existingAmount sql.NullFloat64
 	var existingCreatedAt sql.NullTime
-	if err := tx.QueryRow(r.Context(), `
+
+	err = tx.QueryRow(r.Context(), `
 		SELECT id, booking_id, payment_type, status, amount, created_at
 		FROM payments
 		WHERE booking_id = $1 AND idempotency_key = $2
-	`, bookingID, idempotencyKey).Scan(&existingID, &existingBookingID, &existingPaymentType, &existingStatus, &existingAmount, &existingCreatedAt); err == nil {
+	`, bookingID, idempotencyKey).Scan(&existingID, &existingBookingID, &existingPaymentType, &existingStatus, &existingAmount, &existingCreatedAt)
+
+	paymentID := ""
+	reusePendingRecord := false
+	switch {
+	case err == nil && existingStatus.String == "completed":
+		// Idempotent dedup — return the already-completed payment.
 		if err := json.NewEncoder(w).Encode(PaymentResponse{
 			ID:          existingID.String,
 			BookingID:   existingBookingID.String,
@@ -1923,32 +1935,42 @@ func CreateTipPayment(w http.ResponseWriter, r *http.Request) {
 			log.Printf("Failed to encode JSON response: %v", err)
 		}
 		return
-	} else if !errors.Is(err, pgx.ErrNoRows) {
+	case err == nil && existingStatus.String == "pending":
+		// Previous Square call failed — reuse the pending record and re-attempt.
+		paymentID = existingID.String
+		reusePendingRecord = true
+	case err != nil && !errors.Is(err, pgx.ErrNoRows):
 		log.Printf("Failed to check tip idempotency: %v", err)
 	}
 
-	record := PaymentRecord{
+	if !reusePendingRecord {
-		BookingID:      bookingID,
+		record := PaymentRecord{
-		PaymentType:    "tip",
+			BookingID:      bookingID,
-		PaymentMethod:  "online_square",
+			PaymentType:    "tip",
-		Status:         "pending",
+			PaymentMethod:  "online_square",
-		Amount:         float64(req.Amount) / 100.0,
+			Status:         "pending",
-		IdempotencyKey: &idempotencyKey,
+			Amount:         float64(req.Amount) / 100.0,
-		Fees:           0,
+			IdempotencyKey: &idempotencyKey,
-		UserSavedCardID: savedCardID,
+			Fees:           0,
-		CreatedAt:      clock.Now(),
+			UserSavedCardID: savedCardID,
-		UpdatedAt:      clock.Now(),
+			CreatedAt:      clock.Now(),
-		CreatedBy:      &userID,
+			UpdatedAt:      clock.Now(),
+			CreatedBy:      &userID,
+		}
+
+		paymentID, err = service.CreatePaymentRecordTx(r.Context(), tx, record, nil)
+		if err != nil {
+			log.Printf("Failed to create payment record: %v", err)
+			http.Error(w, "internal server error", http.StatusInternalServerError)
+			return
+		}
+		ApplyVATToBookingPayment(r.Context(), tx, paymentID)
 	}
 
-	paymentID, err := service.CreatePaymentRecordTx(r.Context(), tx, record, nil)
+	// Always commit the (possibly nested/savepoint) transaction. In the reuse
-	if err != nil {
+	// path the savepoint is empty, but committing it releases the savepoint so
-		log.Printf("Failed to create payment record: %v", err)
+	// the deferred rollback becomes a no-op — otherwise that rollback would
-		http.Error(w, "internal server error", http.StatusInternalServerError)
+	// undo the status UPDATE executed later on the same connection.
-		return
-	}
-	ApplyVATToBookingPayment(r.Context(), tx, paymentID)
-
 	if err := tx.Commit(r.Context()); err != nil {
 		log.Printf("Failed to commit transaction: %v", err)
 		http.Error(w, "internal server error", http.StatusInternalServerError)

backend/handlers/payments/payments_test.go

@@ -1933,6 +1933,62 @@ func TestTipPayment_WithSavedCard(t *testing.T) {
 	assert.NotEmpty(t, resp.CardLast4)
 }
 
+func TestTipPayment_RetryPending_ReattemptsCharge(t *testing.T) {
+	t.Parallel()
+	ctx, tx := testutils.SetupTestTx(t)
+
+	userID, bookingID, _ := setupTestData(t, ctx, tx)
+	userToken := jwt.GenerateUserToken(userID)
+
+	// Create a completed payment so the tip is allowed.
+	payID, err := fixtures.CreateTestPayment(tx, bookingID, 5000.00, "online_square", "full", "completed")
+	require.NoError(t, err)
+	squarePayID := "sqp_test_retry"
+	_, err = tx.Exec(ctx, "UPDATE payments SET square_payment_id = $1 WHERE id = $2", squarePayID, payID)
+	require.NoError(t, err)
+
+	// Create a saved card for this user.
+	var savedCardID string
+	err = tx.QueryRow(ctx, `
+		INSERT INTO user_saved_cards (user_id, square_card_id, brand, last_4, exp_month, exp_year, fingerprint)
+		VALUES ($1, 'ccof_mock_retry', 'VISA', '1111', 12, 2030, 'sqfp_mock_retry')
+		RETURNING id
+	`, userID).Scan(&savedCardID)
+	require.NoError(t, err)
+
+	// Simulate a failed prior attempt: a PENDING tip record with the same
+	// idempotency key the frontend will send on retry. The handler must NOT
+	// short-circuit on this — it must re-attempt the Square charge.
+	key := "tip-retry-key-123"
+	_, err = tx.Exec(ctx, `
+		INSERT INTO payments (booking_id, payment_type, payment_method, status, amount, idempotency_key, created_at, updated_at, created_by)
+		VALUES ($1, 'tip', 'online_square', 'pending', 10.00, $2, NOW(), NOW(), $3)
+	`, bookingID, key, userID)
+	require.NoError(t, err)
+
+	req := CreateTipPaymentRequest{
+		Amount:         1000,
+		CardID:         &savedCardID,
+		IdempotencyKey: key,
+	}
+
+	handler := CreateTipPayment
+	w := makePaymentRequest(handler, "POST", "/api/bookings/"+bookingID+"/tip", req, userToken, ctx)
+	require.Equal(t, http.StatusOK, w.Code, "body: %s", w.Body.String())
+
+	var resp PaymentResponse
+	require.NoError(t, parsePaymentResponseBody(w, &resp))
+	assert.Equal(t, "completed", resp.Status, "retry of a pending record must re-attempt and complete, not return the stale pending record")
+
+	// Exactly one payment record for this key, now completed.
+	var count int
+	var status string
+	err = tx.QueryRow(ctx, `SELECT COUNT(*), MAX(status) FROM payments WHERE idempotency_key = $1`, key).Scan(&count, &status)
+	require.NoError(t, err)
+	assert.Equal(t, 1, count, "must reuse the pending record, not insert a duplicate")
+	assert.Equal(t, "completed", status)
+}
+
 func TestTipPayment_TransactionFailure_SkipsSquare(t *testing.T) {
 	t.Parallel()
 	ctx, tx := testutils.SetupTestTx(t)

backend/handlers/payments/till.go

@@ -522,7 +522,7 @@ func GetTillCheckoutStatus(w http.ResponseWriter, r *http.Request) {
 
 	paymentResult, err := SquareClient.GetCheckout(r.Context(), checkoutID)
 	if err != nil {
-		if err.Error() == "checkout pending" {
+		if errors.Is(err, square.ErrCheckoutPending) {
 			if err := json.NewEncoder(w).Encode(PaymentStatusResponse{Status: "PENDING"}); err != nil {
 				log.Printf("Failed to encode JSON response: %v", err)
 			}

backend/internal/square/square_dev.go

@@ -261,7 +261,7 @@ func (m *MockClient) GetCheckout(ctx context.Context, checkoutID string) (*Payme
 	}
 
 	if checkout.Status == "PENDING" {
-		return nil, fmt.Errorf("checkout pending")
+		return nil, ErrCheckoutPending
 	}
 
 	result, ok := m.completed[checkoutID]

backend/internal/square/square_http_client.go

@@ -5,6 +5,7 @@ import (
 	"context"
 	"crypto/sha256"
 	"encoding/json"
+	"errors"
 	"fmt"
 	"io"
 	"net/http"
@@ -13,6 +14,12 @@ import (
 	"time"
 )
 
+// ErrCheckoutPending is returned by GetCheckout when a terminal checkout has
+// not yet completed. Handlers use errors.Is(err, ErrCheckoutPending) rather
+// than string comparison, so behaviour is identical across the mock and the
+// real HTTP client.
+var ErrCheckoutPending = errors.New("checkout pending")
+
 // ---------------------------------------------------------------------------
 // Square REST API constants.
 // ---------------------------------------------------------------------------
@@ -175,14 +182,18 @@ type sqFee struct {
 type sqTerminalCheckoutRequest struct {
 	IdempotencyKey string                    `json:"idempotency_key"`
 	Checkout       sqTerminalCheckoutPayload `json:"checkout"`
-	DeviceID       string                    `json:"device_id,omitempty"`
 }
 
 type sqTerminalCheckoutPayload struct {
-	AmountMoney sqMoney `json:"amount_money"`
+	AmountMoney  sqMoney                 `json:"amount_money"`
-	ReferenceID string  `json:"reference_id,omitempty"`
+	ReferenceID  string                  `json:"reference_id,omitempty"`
-	Note        string  `json:"note,omitempty"`
+	Note         string                  `json:"note,omitempty"`
-	CustomerID  string  `json:"customer_id,omitempty"`
+	CustomerID   string                  `json:"customer_id,omitempty"`
+	DeviceOptions *sqDeviceOptions       `json:"device_options,omitempty"`
+}
+
+type sqDeviceOptions struct {
+	DeviceID string `json:"device_id"`
 }
 
 type sqTerminalCheckoutResponse struct {
@@ -238,8 +249,8 @@ type sqCreateCardRequest struct {
 }
 
 type sqCardPayload struct {
-	ExpMonth       int    `json:"exp_month"`
+	ExpMonth       *int   `json:"exp_month,omitempty"`
-	ExpYear        int    `json:"exp_year"`
+	ExpYear        *int   `json:"exp_year,omitempty"`
 	CardholderName string `json:"cardholder_name,omitempty"`
 	CustomerID     string `json:"customer_id,omitempty"`
 }
@@ -295,7 +306,9 @@ func createCheckoutHTTP(ctx context.Context, req CreateCheckoutReq) (*CheckoutRe
 			Note:        req.Note,
 			CustomerID:  req.CustomerID,
 		},
-		DeviceID: req.DeviceID,
+	}
+	if req.DeviceID != "" {
+		body.Checkout.DeviceOptions = &sqDeviceOptions{DeviceID: req.DeviceID}
 	}
 	var resp sqTerminalCheckoutResponse
 	if err := hc.doJSON(ctx, http.MethodPost, "/v2/terminals/checkouts", body, &resp); err != nil {
@@ -312,6 +325,9 @@ func getCheckoutHTTP(ctx context.Context, checkoutID string) (*PaymentResult, er
 	}
 	tc := tcResp.Checkout
 	if tc.Status != "COMPLETED" {
+		if tc.Status == "PENDING" || tc.Status == "IN_PROGRESS" {
+			return nil, ErrCheckoutPending
+		}
 		return nil, fmt.Errorf("square: checkout %s is %s (not COMPLETED)", checkoutID, tc.Status)
 	}
 	if len(tc.PaymentIDs) == 0 {
@@ -351,8 +367,6 @@ func createCardOnFileHTTP(ctx context.Context, userID, cardToken string) (*CardO
 		SourceID:       cardToken,
 		Card: sqCardPayload{
 			CustomerID: userID,
-			ExpMonth:   0,
-			ExpYear:    0,
 		},
 	}
 	var resp sqCreateCardResponse

obsidian/Crussell/Future Work - Gap Backlog.md

@@ -35,7 +35,7 @@ These are things that work fine in dev (with mocks) but need real implementation
 | P8 | **Social auth stubs (Google/Microsoft/Facebook)** | L (2-3d) | Backend + Frontend | `handlers/auth/social.go` is 1 line (`package auth`). Frontend login page has 3 social buttons that show `toast.info("${provider} login coming soon")`. The `user_social_logins` table and `account_type` enum values exist from early schema design. | The schema was designed for social auth from the start (table + enum values). The OAuth flow itself was never implemented. Buttons exist as UI placeholders. |
 | P9 | **Tip payments: replace placeholder card tokens** | S (1d) | Frontend | ✅ COMPLETED July 2026 — `card_token: 'placeholder'` replaced with real saved card selection + CardInput with Luhn/expiry/CVC validation across all 3 tip pages. | |
 | P10 | **No automated database backups** | M (1d) | Infrastructure | PostgreSQL volume is persistent in Docker but no `pg_dump` cron, no point-in-time recovery. | Standard production DB setup task. |
-| P11 | **Square Web Payments SDK: replace CardInput with nonce-based flow** | M (3-5d) | Frontend + Backend | Frontend still sends raw PAN, expiry, and CVC as `new_card_token` for all card entry flows (tips, booking payment, gift cards, account add card, till purchases). In production, Square's API requires a `cnon:xxx` nonce generated by the Web Payments SDK. The mock (`square_dev.go`) parses raw PANs (detecting brand from first digit), masking this failure in development. | **Action plan:** 1) Load Square Web Payments SDK (script tag in `app.html` or via `@square/web-payments-sdk` npm). 2) Replace `CardInput.svelte` (hand-rolled inputs) with Square's native card form (`payments.card()`). 3) Call `card.tokenize()` to get `cnon:xxx` nonce client-side. 4) Send only the nonce as `new_card_token`. 5) Remove `card_expiry`/`card_cvc` from request bodies (already removed from tip flows). 6) Remove `CreateCardOnFileRaw` from production paths. |
+| P11 | **Square Web Payments SDK: replace CardInput with nonce-based flow** | M (3-5d) | Frontend + Backend | Frontend still sends raw PAN, expiry, and CVC as `new_card_token` for all card entry flows (tips, booking payment, gift cards, account add card, till purchases). In production, Square's API requires a `cnon:xxx` nonce generated by the Web Payments SDK. The mock now mirrors production and rejects raw PANs (`CreateCardOnFileRaw` is blocked; `CreateCardOnFile` accepts only `cnon:`/`ccof:` tokens) — so these new-card flows are currently a dead end in BOTH dev and prod until this is landed or the UI is gated. | **Action plan:** 1) Load Square Web Payments SDK (script tag in `app.html` or via `@square/web-payments-sdk` npm). 2) Replace `CardInput.svelte` (hand-rolled inputs) with Square's native card form (`payments.card()`). 3) Call `card.tokenize()` to get `cnon:xxx` nonce client-side. 4) Send only the nonce as `new_card_token`. 5) Remove `card_expiry`/`card_cvc` from request bodies (already removed from tip flows). 6) Remove `CreateCardOnFileRaw` from production paths. |
 
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obsidian/Crussell/plans/p11-square-web-payments-sdk.md

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+# P11 — Square Web Payments SDK Implementation Plan
+
+**Status:** READY TO PICK UP (deferred from July 2026 session)
+**Owner:** Agent implementing P11 (Square Web Payments SDK)
+**Estimated effort:** 3-5 days
+**Backlog reference:** `Future Work - Gap Backlog.md` item P11
+
+---
+
+## Executive Summary
+
+Every "enter a new card" flow in the app is currently a **dead end**. The frontend sends raw PAN, expiry, and CVC as `new_card_token` with no Square Web Payments SDK tokenization. The backend mock AND production both now reject raw PANs (PCI-DSS parity — `CreateCardOnFileRaw` is blocked, `CreateCardOnFile` accepts only `cnon:`/`ccof:` tokens). So a user entering a new card gets a guaranteed 500. **This plan makes new-card payments actually work** by integrating Square's Web Payments SDK client-side to generate `cnon:xxx` nonces.
+
+---
+
+## Current State (verified July 2026)
+
+### Frontend — 6 flows send raw PAN as `new_card_token`:
+1. `frontend/src/routes/tip/+page.svelte` (~line 283) — `body.new_card_token = newCardNumber.replace(/\s/g, '')`
+2. `frontend/src/routes/pay-tip/[id]/+page.svelte` (~line 331) — same
+3. `frontend/src/lib/components/account/UserBookingModal.svelte` (~line 353) — same (tip modal)
+4. `frontend/src/lib/components/payments/UserPaymentModal.svelte` (~line 348) — booking payment
+5. `frontend/src/lib/components/booking/BookingFlow.svelte` (~line 359) — deposit
+6. `frontend/src/routes/account/+page.svelte` (~line 332) — Buy a Gift Card
+
+Plus raw PAN + CVC to add-card (`account/+page.svelte:577` → `CreatePaymentMethodFromDetails` → `CreateCardOnFileRaw`) and admin till (`GiftCardsManagement.svelte:655` → `till.go:439` → `CreateCardOnFileRaw`).
+
+### The reusable `CardSelection.svelte` component:
+`frontend/src/lib/components/payments/CardSelection.svelte` — the standard card-selection UI (saved card list + "Use a new card" + `CardInput` with blur-based Luhn/expiry/CVC validation). **Currently applied to only 1 of 5 card UIs** (UserPaymentModal). The tip flows, account Buy Gift Card, account Add Card, and BookingFlow still have ~100 duplicated lines each.
+
+### `CardInput.svelte`:
+`frontend/src/lib/components/payments/CardInput.svelte` — the hand-rolled card entry form (number/expiry/CVC inputs, formatNumber/formatExpiry, onfieldblur/onfieldinput callbacks). **This is what gets replaced by Square's native card form.**
+
+### Backend (already P11-ready):
+- `backend/internal/square/square_http_client.go` — `createCardOnFileHTTP` accepts a `source_id` token and calls `POST /v2/cards`. Works with `cnon:xxx` nonces.
+- `backend/handlers/payments/handlers.go` — `CreateTipPayment` accepts `new_card_token` and passes it as the source. Works with nonces.
+- `CreatePaymentMethodFromDetails` (service.go:496) calls `CreateCardOnFileRaw` — **needs migration to the nonce path**.
+- Till `online_square` (till.go:439) calls `CreateCardOnFileRaw` — **needs migration to the nonce path**.
+
+---
+
+## Prerequisites
+
+1. **Square application credentials**:
+   - `SQUARE_APPLICATION_ID` (client-side, public)
+   - `SQUARE_LOCATION_ID` (already used server-side)
+   - Frontend needs the application ID in the browser context (e.g. `PUBLIC_SQUARE_APPLICATION_ID` Vite env var)
+2. **Square account with Web Payments enabled** and a card processing merchant account.
+3. Frontend must be HTTPS (or localhost) for the SDK to load.
+
+---
+
+## Implementation Steps
+
+### Step 1 — Load the Square Web Payments SDK
+
+Two options (pick one):
+- **npm**: `@square/web-payments-sdk` — provides `Square.payments(appId, locationId)`
+- **script tag**: `<script src="https://sandbox.web.squarecdn.com/v1/square.js" type="text/javascript"></script>` in `app.html` (sandbox) or `https://web.squarecdn.com/v1/square.js` (prod)
+
+Load based on `SQUARE_ENVIRONMENT` so sandbox/prod use the right URL.
+
+### Step 2 — Create a Square card form component
+
+Replace `CardInput.svelte`'s hand-rolled inputs with Square's native card form:
+```js
+const payments = window.Square.payments(appId, locationId);
+const card = await payments.card();
+await card.attach('#square-card-container');
+// ...on submit:
+const tokenResult = await card.tokenize();
+// tokenResult.token → "cnon:xxx"
+```
+
+**Design decision**: Either:
+- (a) Embed the Square form inside `CardInput.svelte` (keep the `bind:cardNumber` etc. API surface but use Square's iframe internally — the inputs become read-only display), OR
+- (b) Create a new `SquareCardInput.svelte` and swap it into `CardSelection.svelte` when a Square app ID is configured, falling back to the hand-rolled form when `SQUARE_APPLICATION_ID` is absent (keeps dev/testing working without Square).
+
+**Recommendation**: (b) — a `SquareCardInput.svelte` with a fallback. This keeps local dev usable when no Square app ID is configured, while production uses real tokenization.
+
+### Step 3 — Update the 6 payment flows to send nonces
+
+For each flow, `new_card_token` must become the `cnon:xxx` token from `card.tokenize()`, NOT the raw PAN. Since all 6 flows go through `CardSelection.svelte` (or the fallback path), the cleanest approach:
+
+1. First **extend `CardSelection.svelte` to all 5 remaining card UIs** (tip ×3, account Buy Gift Card, account Add Card, BookingFlow) — this centralises the card-selection logic so P11's change is one place, not six.
+2. Then swap the card entry inside `CardSelection.svelte` to use `SquareCardInput` (Step 2b).
+3. Remove `card_expiry`/`card_cvc` from all request bodies (already removed from tip flows).
+
+### Step 4 — Migrate the two raw-PAN backend paths
+
+- `CreatePaymentMethodFromDetails` (account add-card): change `CreateCardOnFileRaw` call to use the nonce path (`CreateCardOnFile` with the `cnon:xxx` token).
+- Till `online_square` (`till.go:439`): same migration — `CreateCardOnFileRaw` → `CreateCardOnFile` with a nonce. The frontend `GiftCardsManagement.svelte` till flow must send the nonce instead of raw PAN.
+
+### Step 5 — Remove `CreateCardOnFileRaw` entirely
+
+Once both callers are migrated:
+- Delete `CreateCardOnFileRaw` from the `SquareClient` interface (`backend/internal/square/types.go:140`)
+- Delete from all 3 implementations (MockClient, ProdClient, devProdClient)
+- Delete the PCI-block error stubs
+- Update the `square_dev_test.go` tests that assert the raw-PAN rejection (`TestDevClient_CreateCardOnFileRaw_Rejected_ProdParity` → the method no longer exists)
+- Update handler tests that assert the 500 on raw-PAN add-card
+
+### Step 6 — Update docs
+
+- `README.md` line 9: remove the "P11 — production nonce integration is backlog item P11" caveat once landed
+- `Future Work - Gap Backlog.md` P11: mark completed
+- `Feature Catalog.md` and `Technical Manual.md`: update "Web Payments SDK (online)" claims if they reference the old state
+
+---
+
+## Testing Plan
+
+1. **Unit tests**:
+   - `square_http_client_test.go`: add request-shape tests via `httptest.Server` for `createCardOnFileHTTP` (verify `source_id` is the token, `idempotency_key` deterministic, no raw PAN in body) — the HTTP client currently has only 2 tests (both `paymentFromSquare`).
+   - Error-path tests for the HTTP client (non-2xx, malformed body).
+2. **Integration tests**:
+   - Handler tests using `cnon:` tokens through the mock (the mock accepts `cnon:` nonces) — restore success-path coverage for `TestCreatePaymentMethod_HappyPath` etc. (currently rewritten to assert the raw-PAN 500).
+   - Add a test: card created with nonce → payment with saved card works.
+3. **Manual/sandbox tests** (requires Square sandbox credentials):
+   - Each of the 6 flows: enter new card → tokenize → pay → verify charge in Square dashboard.
+   - Saved-card flow still works.
+   - Refund still works.
+
+---
+
+## Risks / Gotchas
+
+- **Square iframe requires HTTPS** — localhost is exempt, but any non-local dev URL needs TLS.
+- **Tokenization is one-shot** — a `cnon:` nonce is single-use. The idempotency key logic (cached per payment attempt) handles retries, but a retry must NOT re-tokenize if the first tokenize succeeded and the payment failed — the backend's idempotency dedup handles this, but the frontend should reuse the cached token on retry if the payment record is pending.
+- **The hand-rolled `CardInput.svelte` Luhn/expiry validation becomes cosmetic** — Square's iframe does the real validation. Keep the display validation for UX, but don't block submission on it alone.
+- **PCI-DSS scope**: with nonces, PAN never touches our server. The `CreateCardOnFileRaw` migration is essential — do NOT leave it in place.
+
+---
+
+## Definition of Done
+
+- [ ] Square Web Payments SDK loads (sandbox + prod URLs, env-gated)
+- [ ] `SquareCardInput` (or embedded form) tokenizes cards → `cnon:xxx`
+- [ ] All 6 payment flows send nonces, not raw PANs
+- [ ] `CardSelection.svelte` used by all 5 card UIs
+- [ ] `CreateCardOnFileRaw` deleted from interface + all implementations
+- [ ] All handler tests pass with nonce-based flows
+- [ ] Sandbox smoke test: new-card payment succeeds end-to-end
+- [ ] Docs updated