feat(customers): store customer phone numbers as 62…

A customer's phone number (customers.phone_number, the one they log in with) has
one stored form, 62 followed by the number without its 0: 6281234561234.
util.NormalizePhoneNumber rewrites 0812…, +62 812…, 62812…, 812… and +62 0812…,
with spaces, dashes, dots or parentheses, to it, and refuses anything that is not
an Indonesian mobile number (628 and 7 to 11 more digits).

It is applied wherever a customer types their number: check-phone, register,
login and resend-OTP (the validator rewrites the request), and the transfer
recipient. Before, the number was matched as typed and a leading 0 was refused,
so the same customer written another way was not found. The masked recipient
stays 08**-****-1234 as customers write numbers.

Migration 000116 rewrites the numbers already stored in customers and
otp_sessions. When several become the same number, the customer that already has
it keeps it, else a registered one, else the oldest; the others, and numbers that
are not Indonesian mobile numbers, are left as they are and cannot log in until
fixed by hand (the query to find them is in the migration). Down does nothing.

The migration was run, twice, against Postgres with a reduced customers and
otp_sessions schema and sample numbers; not against the real schema. The
Postgres tests were not run. customers.phone (the POS contact number) is not
touched.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

internal/processor/wallet_exchange_processor_test.go

@@ -152,7 +152,7 @@ func (f *movePinFake) VerifyPin(_ context.Context, _ uuid.UUID, pin string, acti
 
 func TestWalletExchange_DefaultRateIsOneToOne(t *testing.T) {
 	e := newWalletMoveEnv(t)
-	c := e.member("Budi Santoso", "081234561234")
+	c := e.member("Budi Santoso", "6281234561234")
 	e.earnCoins(t, c, 50, nil)
 
 	res, err := e.exchanges().Exchange(e.ctx, c, 50, "482913", "key-1", models.CustomerPinRequestInfo{})
@@ -187,7 +187,7 @@ func TestWalletExchange_DefaultRateIsOneToOne(t *testing.T) {
 func TestWalletExchange_TenCoinsForThreePoints(t *testing.T) {
 	e := newWalletMoveEnv(t)
 	e.settings.Exchange = models.LoyaltyExchangeSettings{CoinAmount: 10, PointAmount: 3}
-	c := e.member("Budi", "081234561234")
+	c := e.member("Budi", "6281234561234")
 	e.earnCoins(t, c, 35, nil)
 
 	preview, err := e.exchanges().Preview(e.ctx, c, 30)
@@ -206,7 +206,7 @@ func TestWalletExchange_TenCoinsForThreePoints(t *testing.T) {
 func TestWalletExchange_RefusesAmountsThatAreNotAMultiple(t *testing.T) {
 	e := newWalletMoveEnv(t)
 	e.settings.Exchange = models.LoyaltyExchangeSettings{CoinAmount: 10, PointAmount: 3}
-	c := e.member("Budi", "081234561234")
+	c := e.member("Budi", "6281234561234")
 	e.earnCoins(t, c, 50, nil)
 
 	preview, err := e.exchanges().Preview(e.ctx, c, 25)
@@ -227,7 +227,7 @@ func TestWalletExchange_RefusesAmountsThatAreNotAMultiple(t *testing.T) {
 func TestWalletExchange_NeverOutlivesTheCoinLot(t *testing.T) {
 	e := newWalletMoveEnv(t)
 	e.settings.Exchange = models.LoyaltyExchangeSettings{CoinAmount: 10, PointAmount: 3}
-	c := e.member("Budi", "081234561234")
+	c := e.member("Budi", "6281234561234")
 	soon, later := e.at(24*time.Hour), e.at(48*time.Hour)
 	first := e.earnCoins(t, c, 15, soon)
 	second := e.earnCoins(t, c, 15, later)
@@ -268,7 +268,7 @@ func TestWalletExchange_NeverOutlivesTheCoinLot(t *testing.T) {
 func TestWalletExchange_LotTooSmallForAWholePointGivesNone(t *testing.T) {
 	e := newWalletMoveEnv(t)
 	e.settings.Exchange = models.LoyaltyExchangeSettings{CoinAmount: 10, PointAmount: 1}
-	c := e.member("Budi", "081234561234")
+	c := e.member("Budi", "6281234561234")
 	e.earnCoins(t, c, 5, e.at(time.Hour))
 	e.earnCoins(t, c, 5, nil)
 
@@ -281,7 +281,7 @@ func TestWalletExchange_LotTooSmallForAWholePointGivesNone(t *testing.T) {
 
 func TestWalletExchange_NotEnoughCoins(t *testing.T) {
 	e := newWalletMoveEnv(t)
-	c := e.member("Budi", "081234561234")
+	c := e.member("Budi", "6281234561234")
 	e.earnCoins(t, c, 5, nil)
 
 	preview, err := e.exchanges().Preview(e.ctx, c, 6)
@@ -295,7 +295,7 @@ func TestWalletExchange_NotEnoughCoins(t *testing.T) {
 
 func TestWalletExchange_WrongPinMovesNothing(t *testing.T) {
 	e := newWalletMoveEnv(t)
-	c := e.member("Budi", "081234561234")
+	c := e.member("Budi", "6281234561234")
 	e.earnCoins(t, c, 5, nil)
 
 	_, err := e.exchanges().Exchange(e.ctx, c, 5, "000000", "key-1", models.CustomerPinRequestInfo{})
@@ -307,7 +307,7 @@ func TestWalletExchange_WrongPinMovesNothing(t *testing.T) {
 
 func TestWalletExchange_RetryReturnsTheFirstExchangeAtItsRate(t *testing.T) {
 	e := newWalletMoveEnv(t)
-	c := e.member("Budi", "081234561234")
+	c := e.member("Budi", "6281234561234")
 	e.earnCoins(t, c, 100, nil)
 
 	first, err := e.exchanges().Exchange(e.ctx, c, 40, "482913", "key-1", models.CustomerPinRequestInfo{})
@@ -330,7 +330,7 @@ func TestWalletExchange_RetryReturnsTheFirstExchangeAtItsRate(t *testing.T) {
 
 func TestWalletExchange_RequiresAnIdempotencyKey(t *testing.T) {
 	e := newWalletMoveEnv(t)
-	c := e.member("Budi", "081234561234")
+	c := e.member("Budi", "6281234561234")
 	e.earnCoins(t, c, 5, nil)
 
 	_, err := e.exchanges().Exchange(e.ctx, c, 5, "482913", " ", models.CustomerPinRequestInfo{})
@@ -344,7 +344,7 @@ func TestWalletExchange_CappedByThePointExpiry(t *testing.T) {
 	e := newWalletMoveEnv(t)
 	e.now = wib(2026, 6, 1, 10, 0)
 	e.settings.PointExpiry = rolling(30, "DAY", false)
-	c := e.member("Budi", "081234561234")
+	c := e.member("Budi", "6281234561234")
 	soon, later := e.at(24*time.Hour), e.at(90*24*time.Hour)
 	e.earnCoins(t, c, 10, soon)
 	e.earnCoins(t, c, 10, later)

internal/processor/wallet_expiry_processor_test.go

@@ -54,7 +54,7 @@ func (e *walletMoveEnv) expiry(notifier customerNotifier) (*WalletExpiryProcesso
 
 func TestWalletExpiry_ExpiresWhatIsDueAndTellsTheCustomer(t *testing.T) {
 	e := newWalletMoveEnv(t)
-	a := e.member("Anita", "081200005678")
+	a := e.member("Anita", "6281200005678")
 	ord := earn(a, 150, e.at(-time.Hour))
 	ord.Description = "Belanja #ORD-0098"
 	due := e.credit(t, ord)
@@ -102,7 +102,7 @@ func TestWalletExpiry_ExpiresWhatIsDueAndTellsTheCustomer(t *testing.T) {
 
 func TestWalletExpiry_RunningAgainExpiresNothingMore(t *testing.T) {
 	e := newWalletMoveEnv(t)
-	a := e.member("Anita", "081200005678")
+	a := e.member("Anita", "6281200005678")
 	e.credit(t, earn(a, 150, e.at(-time.Hour)))
 	notifier := &notifierFake{}
 
@@ -128,7 +128,7 @@ func TestWalletExpiry_RunningAgainExpiresNothingMore(t *testing.T) {
 
 func TestWalletExpiry_OneFailingLotDoesNotStopTheOthers(t *testing.T) {
 	e := newWalletMoveEnv(t)
-	a := e.member("Anita", "081200005678")
+	a := e.member("Anita", "6281200005678")
 	e.credit(t, earn(a, 150, e.at(-time.Hour)))
 	p, repo := e.expiry(nil)
 	// A lot listed that ExpireLot cannot find.
@@ -142,7 +142,7 @@ func TestWalletExpiry_OneFailingLotDoesNotStopTheOthers(t *testing.T) {
 
 func TestWalletExpiry_NothingDue(t *testing.T) {
 	e := newWalletMoveEnv(t)
-	a := e.member("Anita", "081200005678")
+	a := e.member("Anita", "6281200005678")
 	e.credit(t, earn(a, 150, e.at(time.Hour)))
 	notifier := &notifierFake{}
 	p, _ := e.expiry(notifier)
@@ -206,7 +206,7 @@ func TestWalletExpiry_RemindsOncePerDayBeforeExpiry(t *testing.T) {
 	e.now = wib(2026, 10, 25, 9, 0)
 	e.settings.PointExpiry.ReminderDays = 7
 	e.settings.CoinExpiry.ReminderDays = 0 // no reminders for EnakCoin
-	a := e.member("Anita", "081200005678")
+	a := e.member("Anita", "6281200005678")
 	oct31 := wib(2026, 10, 31, 23, 59)
 	nov30 := wib(2026, 11, 30, 23, 59)
 	e.credit(t, earn(a, 100, &oct31))

internal/processor/wallet_move_db_test.go

@@ -2,6 +2,7 @@ package processor
 
 import (
 	"context"
+	"encoding/binary"
 	"fmt"
 	"os"
 	"sync"
@@ -42,7 +43,7 @@ func walletMoveDB(t *testing.T) (db *gorm.DB, org, a, b uuid.UUID) {
 	require.NoError(t, err)
 
 	org, a, b = uuid.New(), uuid.New(), uuid.New()
-	phoneA, phoneB := "08"+a.String()[:10], "08"+b.String()[:10]
+	phoneA, phoneB := walletTestPhone(a), walletTestPhone(b)
 	require.NoError(t, db.Exec(`INSERT INTO organizations (id, name, plan_type) VALUES (?, 'wallet move test', 'basic')`, org).Error)
 	require.NoError(t, db.Exec(`INSERT INTO customers (id, organization_id, name, phone_number) VALUES (?, ?, 'Anita', ?), (?, ?, 'Budi Santoso', ?)`,
 		a, org, phoneA, b, org, phoneB).Error)
@@ -117,7 +118,7 @@ func TestWalletTransfer_BothWaysAtOnceAgainstPostgres(t *testing.T) {
 		_, err := wallet.Credit(ctx, earn(b, 100, nil))
 		return err
 	}))
-	phone := func(id uuid.UUID) string { return "08" + id.String()[:10] }
+	phone := walletTestPhone
 
 	const rounds = 10
 	errs := make(chan error, 2*rounds)
@@ -235,3 +236,8 @@ func TestWalletExpiry_TwoInstancesAgainstPostgres(t *testing.T) {
 	assert.Equal(t, int64(10), expires)
 	assert.Zero(t, left)
 }
+
+// walletTestPhone is a phone number in its stored form, 628…, unique to the customer.
+func walletTestPhone(id uuid.UUID) string {
+	return fmt.Sprintf("628%09d", binary.BigEndian.Uint64(id[:8])%1_000_000_000)
+}

internal/processor/wallet_trace_processor_test.go

@@ -85,8 +85,8 @@ func findRow(t *testing.T, e *walletMoveEnv, customerID uuid.UUID, txType string
 // redeems 30. Tracing B's redemption leads to A's order #ORD-1.
 func TestWalletTrace_RedemptionLeadsBackToTheSendersOrder(t *testing.T) {
 	e := newWalletMoveEnv(t)
-	a := e.member("Anita", "081200005678")
-	b := e.member("Budi Santoso", "081234561234")
+	a := e.member("Anita", "6281200005678")
+	b := e.member("Budi Santoso", "6281234561234")
 	ord1 := earn(a, 100, e.at(30*24*time.Hour))
 	ord1.Description = "Belanja #ORD-1"
 	ord2 := earn(a, 50, e.at(60*24*time.Hour))
@@ -121,8 +121,8 @@ func TestWalletTrace_RedemptionLeadsBackToTheSendersOrder(t *testing.T) {
 
 func TestWalletTrace_DebitAndCreditOfATransfer(t *testing.T) {
 	e := newWalletMoveEnv(t)
-	a := e.member("Anita", "081200005678")
-	b := e.member("Budi", "081234561234")
+	a := e.member("Anita", "6281200005678")
+	b := e.member("Budi", "6281234561234")
 	e.credit(t, earn(a, 100, e.at(time.Hour)))
 	e.credit(t, earn(a, 50, nil))
 	_, err := e.transfers(nil).Transfer(e.ctx, a, sendPoints(120, "081234561234"), "482913", "key-1", models.CustomerPinRequestInfo{})
@@ -153,7 +153,7 @@ func TestWalletTrace_DebitAndCreditOfATransfer(t *testing.T) {
 
 func TestWalletTrace_OtherOrganizationsRowsAreNotFound(t *testing.T) {
 	e := newWalletMoveEnv(t)
-	a := e.member("Anita", "081200005678")
+	a := e.member("Anita", "6281200005678")
 	res := e.credit(t, earn(a, 10, nil))
 
 	_, err := NewWalletTraceProcessor(walletTraceRepoFake{e}).Trace(e.ctx, uuid.New(), res.Transaction.ID)

internal/processor/wallet_transfer_processor.go

@@ -15,6 +15,7 @@ import (
 	"apskel-pos-be/internal/logger"
 	"apskel-pos-be/internal/models"
 	"apskel-pos-be/internal/repository"
+	"apskel-pos-be/internal/util"
 )
 
 // ErrWalletRecipientNotFound means no customer of the sender's organization has the
@@ -213,10 +214,13 @@ func (p *WalletTransferProcessor) Transfer(ctx context.Context, senderID uuid.UU
 // them: an active customer of the same organization, not the walk-in customer, and
 // not the sender.
 func (p *WalletTransferProcessor) recipient(ctx context.Context, sender *repository.WalletMoveCustomer, phoneNumber string) (*repository.WalletMoveCustomer, error) {
-	phoneNumber = strings.TrimSpace(phoneNumber)
-	if phoneNumber == "" {
+	if strings.TrimSpace(phoneNumber) == "" {
 		return nil, fmt.Errorf("%w: the recipient's phone number is required", ErrWalletMoveRejected)
 	}
+	phoneNumber, err := util.NormalizePhoneNumber(phoneNumber)
+	if err != nil {
+		return nil, fmt.Errorf("%w: the recipient's phone number is not valid", ErrWalletMoveRejected)
+	}
 	recipient, err := p.customers.FindCustomerByPhone(ctx, phoneNumber)
 	if errors.Is(err, repository.ErrWalletNotFound) {
 		return nil, ErrWalletRecipientNotFound
@@ -282,10 +286,14 @@ func maskName(name string) string {
 	return strings.Join(words, " ")
 }
 
-// maskPhoneNumber keeps the first two and the last four digits:
-// "081234561234" → "08**-****-1234".
+// maskPhoneNumber keeps the first two and the last four digits of the number as
+// customers write it, with 0 for 62: "6281234561234" → "08**-****-1234".
 func maskPhoneNumber(phone string) string {
-	runes := []rune(strings.TrimSpace(phone))
+	phone = strings.TrimSpace(phone)
+	if strings.HasPrefix(phone, "62") {
+		phone = "0" + phone[2:]
+	}
+	runes := []rune(phone)
 	if len(runes) < 8 {
 		return "****"
 	}

internal/processor/wallet_transfer_processor_test.go

@@ -37,8 +37,8 @@ func sendPoints(amount int64, phone string) models.WalletTransfer {
 
 func TestWalletTransfer_MovesBalanceWithItsExpiry(t *testing.T) {
 	e := newWalletMoveEnv(t)
-	a := e.member("Anita", "081200005678")
-	b := e.member("Budi Santoso", "081234561234")
+	a := e.member("Anita", "6281200005678")
+	b := e.member("Budi Santoso", "6281234561234")
 	dec, jan := e.at(30*24*time.Hour), e.at(60*24*time.Hour)
 	first := e.credit(t, earn(a, 100, dec))
 	second := e.credit(t, earn(a, 50, jan))
@@ -97,8 +97,8 @@ func TestWalletTransfer_MovesBalanceWithItsExpiry(t *testing.T) {
 
 func TestWalletTransfer_Coins(t *testing.T) {
 	e := newWalletMoveEnv(t)
-	a := e.member("Anita", "081200005678")
-	b := e.member("Budi", "081234561234")
+	a := e.member("Anita", "6281200005678")
+	b := e.member("Budi", "6281234561234")
 	e.earnCoins(t, a, 10, nil)
 
 	_, err := e.transfers(nil).Transfer(e.ctx, a, models.WalletTransfer{Currency: "coin", Amount: 4, RecipientPhone: "081234561234"}, "482913", "key-1", models.CustomerPinRequestInfo{})
@@ -109,14 +109,14 @@ func TestWalletTransfer_Coins(t *testing.T) {
 
 func TestWalletTransfer_RefusesRecipientsItMayNotSendTo(t *testing.T) {
 	e := newWalletMoveEnv(t)
-	a := e.member("Anita", "081200005678")
+	a := e.member("Anita", "6281200005678")
 	e.credit(t, earn(a, 100, nil))
 
-	walkIn := e.member("Walk-in", "081100000000")
+	walkIn := e.member("Walk-in", "6281100000000")
 	e.customers.byID[walkIn].IsDefault = true
-	inactive := e.member("Old", "081100000001")
+	inactive := e.member("Old", "6281100000001")
 	e.customers.byID[inactive].IsActive = false
-	elsewhere := e.member("Other Org", "081100000002")
+	elsewhere := e.member("Other Org", "6281100000002")
 	e.customers.byID[elsewhere].OrganizationID = uuid.New()
 
 	for phone, want := range map[string]error{
@@ -126,6 +126,7 @@ func TestWalletTransfer_RefusesRecipientsItMayNotSendTo(t *testing.T) {
 		"081100000002": ErrWalletRecipientNotFound, // another organization looks like nobody
 		"081999999999": ErrWalletRecipientNotFound,
 		"":             ErrWalletMoveRejected,
+		"021-1234567":  ErrWalletMoveRejected, // not a mobile number
 	} {
 		_, err := e.transfers(nil).Recipient(e.ctx, a, phone)
 		assert.ErrorIs(t, err, want, phone)
@@ -138,18 +139,20 @@ func TestWalletTransfer_RefusesRecipientsItMayNotSendTo(t *testing.T) {
 
 func TestWalletTransfer_RecipientIsMasked(t *testing.T) {
 	e := newWalletMoveEnv(t)
-	a := e.member("Anita", "081200005678")
-	e.member("Budi Santoso", "081234561234")
+	a := e.member("Anita", "6281200005678")
+	e.member("Budi Santoso", "6281234561234")
 
-	got, err := e.transfers(nil).Recipient(e.ctx, a, " 081234561234 ")
-	require.NoError(t, err)
-	assert.Equal(t, &models.WalletTransferRecipient{Name: "Bu*** Sa***", PhoneNumber: "08**-****-1234"}, got)
+	for _, phone := range []string{" 081234561234 ", "6281234561234", "+62 812-3456-1234"} {
+		got, err := e.transfers(nil).Recipient(e.ctx, a, phone)
+		require.NoError(t, err, phone)
+		assert.Equal(t, &models.WalletTransferRecipient{Name: "Bu*** Sa***", PhoneNumber: "08**-****-1234"}, got, phone)
+	}
 }
 
 func TestWalletTransfer_OrganizationLimits(t *testing.T) {
 	e := newWalletMoveEnv(t)
-	a := e.member("Anita", "081200005678")
-	e.member("Budi", "081234561234")
+	a := e.member("Anita", "6281200005678")
+	e.member("Budi", "6281234561234")
 	e.credit(t, earn(a, 1000, nil))
 	e.settings.Transfer = models.LoyaltyTransferSettings{Enabled: true, MinAmount: 10, MaxPerTransaction: ptr(int64(300)), DailyLimit: ptr(int64(500))}
 	send := func(amount int64, key string) error {
@@ -177,8 +180,8 @@ func TestWalletTransfer_OrganizationLimits(t *testing.T) {
 
 func TestWalletTransfer_HeldAfterPinReset(t *testing.T) {
 	e := newWalletMoveEnv(t)
-	a := e.member("Anita", "081200005678")
-	e.member("Budi", "081234561234")
+	a := e.member("Anita", "6281200005678")
+	e.member("Budi", "6281234561234")
 	e.credit(t, earn(a, 100, nil))
 	until := e.now.Add(time.Hour)
 	e.pins.err = &PinError{Code: PinErrTransferBlocked, Until: &until}
@@ -192,8 +195,8 @@ func TestWalletTransfer_HeldAfterPinReset(t *testing.T) {
 
 func TestWalletTransfer_NotEnoughBalance(t *testing.T) {
 	e := newWalletMoveEnv(t)
-	a := e.member("Anita", "081200005678")
-	b := e.member("Budi", "081234561234")
+	a := e.member("Anita", "6281200005678")
+	b := e.member("Budi", "6281234561234")
 	e.credit(t, earn(a, 100, nil))
 	// An expired lot cannot be sent even before the expiry job takes it.
 	e.credit(t, earn(a, 50, e.at(-time.Hour)))
@@ -205,9 +208,9 @@ func TestWalletTransfer_NotEnoughBalance(t *testing.T) {
 
 func TestWalletTransfer_RetryMovesNothingAndTellsNobodyAgain(t *testing.T) {
 	e := newWalletMoveEnv(t)
-	a := e.member("Anita", "081200005678")
-	b := e.member("Budi", "081234561234")
-	e.member("Citra", "081255550000")
+	a := e.member("Anita", "6281200005678")
+	b := e.member("Budi", "6281234561234")
+	e.member("Citra", "6281255550000")
 	e.credit(t, earn(a, 100, nil))
 	notifier := &notifierFake{}
 

internal/util/phone.go

@@ -0,0 +1,41 @@
+package util
+
+import (
+	"errors"
+	"regexp"
+	"strings"
+)
+
+// ErrInvalidPhoneNumber means a phone number is not an Indonesian mobile number.
+var ErrInvalidPhoneNumber = errors.New("invalid phone number format")
+
+// customerPhonePattern is an Indonesian mobile number in its stored form: 62, then the
+// number without its leading 0 (628…, 10 to 14 digits in all).
+var customerPhonePattern = regexp.MustCompile(`^628\d{7,11}$`)
+
+// NormalizePhoneNumber turns a customer's phone number into the one form it is stored
+// and looked up in, 62…: "0812-3456-1234", "+62 812 3456 1234", "62812…" and "812…"
+// all become "6281234561234". Spaces, dashes, dots and parentheses are dropped.
+func NormalizePhoneNumber(raw string) (string, error) {
+	digits := strings.Map(func(r rune) rune {
+		switch r {
+		case ' ', '-', '.', '(', ')':
+			return -1
+		}
+		return r
+	}, strings.TrimSpace(raw))
+	digits = strings.TrimPrefix(digits, "+")
+	switch {
+	case strings.HasPrefix(digits, "620"):
+		// +62 typed in front of a number that kept its 0.
+		digits = "62" + digits[3:]
+	case strings.HasPrefix(digits, "0"):
+		digits = "62" + digits[1:]
+	case strings.HasPrefix(digits, "8"):
+		digits = "62" + digits
+	}
+	if !customerPhonePattern.MatchString(digits) {
+		return "", ErrInvalidPhoneNumber
+	}
+	return digits, nil
+}

internal/util/phone_test.go

@@ -0,0 +1,49 @@
+package util
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestNormalizePhoneNumber(t *testing.T) {
+	for _, raw := range []string{
+		"6281234561234",
+		"+6281234561234",
+		"081234561234",
+		"81234561234",
+		"0812-3456-1234",
+		"+62 812 3456 1234",
+		"(+62) 812.3456.1234",
+		"+62081234561234",
+		" 081234561234 ",
+	} {
+		got, err := NormalizePhoneNumber(raw)
+		require.NoError(t, err, raw)
+		assert.Equal(t, "6281234561234", got, raw)
+	}
+
+	shortest, err := NormalizePhoneNumber("0811234567")
+	require.NoError(t, err)
+	assert.Equal(t, "62811234567", shortest)
+	longest, err := NormalizePhoneNumber("0812345678901")
+	require.NoError(t, err)
+	assert.Equal(t, "62812345678901", longest)
+	_, err = NormalizePhoneNumber("08123456789012")
+	assert.ErrorIs(t, err, ErrInvalidPhoneNumber, "too long")
+
+	for _, raw := range []string{
+		"",
+		"0",
+		"021-1234567",     // a landline, cannot get the WhatsApp OTP
+		"+6521234567",     // not Indonesian
+		"+1 415 555 0100", // not Indonesian
+		"62812",           // too short
+		"0812abc61234",
+		"0812/3456/1234",
+	} {
+		_, err := NormalizePhoneNumber(raw)
+		assert.ErrorIs(t, err, ErrInvalidPhoneNumber, raw)
+	}
+}

internal/validator/customer_auth_validator.go

@@ -9,6 +9,7 @@ import (
 
 	"apskel-pos-be/internal/constants"
 	"apskel-pos-be/internal/contract"
+	"apskel-pos-be/internal/util"
 )
 
 type CustomerAuthValidator interface {
@@ -36,7 +37,7 @@ func (v *CustomerAuthValidatorImpl) ValidateCheckPhoneRequest(req *contract.Chec
 		return errors.New("phone number is required"), constants.ValidationErrorCode
 	}
 
-	if !v.isValidPhoneNumber(req.PhoneNumber) {
+	if !v.normalizePhoneNumber(&req.PhoneNumber) {
 		return errors.New("invalid phone number format"), constants.ValidationErrorCode
 	}
 
@@ -53,7 +54,7 @@ func (v *CustomerAuthValidatorImpl) ValidateRegisterStartRequest(req *contract.R
 		return errors.New("phone number is required"), constants.ValidationErrorCode
 	}
 
-	if !v.isValidPhoneNumber(req.PhoneNumber) {
+	if !v.normalizePhoneNumber(&req.PhoneNumber) {
 		return errors.New("invalid phone number format"), constants.ValidationErrorCode
 	}
 
@@ -161,7 +162,7 @@ func (v *CustomerAuthValidatorImpl) ValidateCustomerLoginRequest(req *contract.C
 		return errors.New("phone number is required"), constants.ValidationErrorCode
 	}
 
-	if !v.isValidPhoneNumber(req.PhoneNumber) {
+	if !v.normalizePhoneNumber(&req.PhoneNumber) {
 		return errors.New("invalid phone number format"), constants.ValidationErrorCode
 	}
 
@@ -174,10 +175,15 @@ func (v *CustomerAuthValidatorImpl) ValidateCustomerLoginRequest(req *contract.C
 }
 
 // Helper validation functions
-func (v *CustomerAuthValidatorImpl) isValidPhoneNumber(phoneNumber string) bool {
-	// Basic phone number validation - adjust regex based on your requirements
-	phoneRegex := regexp.MustCompile(`^\+?[1-9]\d{1,14}$`)
-	return phoneRegex.MatchString(phoneNumber)
+// normalizePhoneNumber rewrites the phone number in the form it is stored in, 62…
+// (util.NormalizePhoneNumber), and reports false when it is not a valid one.
+func (v *CustomerAuthValidatorImpl) normalizePhoneNumber(phoneNumber *string) bool {
+	normalized, err := util.NormalizePhoneNumber(*phoneNumber)
+	if err != nil {
+		return false
+	}
+	*phoneNumber = normalized
+	return true
 }
 
 func (v *CustomerAuthValidatorImpl) isValidDateFormat(date string) bool {
@@ -208,7 +214,7 @@ func (v *CustomerAuthValidatorImpl) ValidateResendOtpRequest(req *contract.Resen
 	}
 
 	// Validate phone number format
-	if !v.isValidPhoneNumber(req.PhoneNumber) {
+	if !v.normalizePhoneNumber(&req.PhoneNumber) {
 		return errors.New("invalid phone number format"), constants.CustomerEntity
 	}