added config for virtual phone number

internal/app/account/phone_change.go

@@ -3,6 +3,7 @@ package account
 import (
 	"context"
 	"crypto/rand"
+	"encoding/binary"
 	"encoding/hex"
 	"fmt"
 	"strings"
@@ -242,14 +243,18 @@ func (s *Service) phoneChangeCaller(ctx context.Context, userID int64, authKeyID
 // collision-retry loop so a store failure can't spin forever.
 const maxEmailSignupPhoneAttempts = 20
 
-// assignEmailSignupDisplayPhone generates a short "888" display number for
-// an email-signup account rebinding to a new email (see
+// assignEmailSignupDisplayPhone generates a short display number for an
+// email-signup account rebinding to a new email (see
 // domain.NewEmailSignupDisplayPhone / auth.Service's SignUp counterpart),
 // re-rolling on the astronomically unlikely collision with an existing
 // account's phone.
 func (s *Service) assignEmailSignupDisplayPhone(ctx context.Context) (string, error) {
+	prefix, err := randomEmailSignupPhonePrefix(s.emailSignupPhonePrefixes)
+	if err != nil {
+		return "", err
+	}
 	for i := 0; i < maxEmailSignupPhoneAttempts; i++ {
-		candidate, err := domain.NewEmailSignupDisplayPhone()
+		candidate, err := domain.NewEmailSignupDisplayPhone(prefix)
 		if err != nil {
 			return "", err
 		}
@@ -262,6 +267,25 @@ func (s *Service) assignEmailSignupDisplayPhone(ctx context.Context) (string, er
 	return "", fmt.Errorf("assign email signup display phone: exhausted %d attempts", maxEmailSignupPhoneAttempts)
 }
 
+// randomEmailSignupPhonePrefix mirrors auth.Service's identical helper
+// (unexported to each package, but must pick with the same fairness): pick
+// one entry at random from prefixes, falling back to domain.EmailPhonePrefix
+// ("888") when the list is empty.
+func randomEmailSignupPhonePrefix(prefixes []string) (string, error) {
+	if len(prefixes) == 0 {
+		return domain.EmailPhonePrefix, nil
+	}
+	if len(prefixes) == 1 {
+		return prefixes[0], nil
+	}
+	var b [8]byte
+	if _, err := rand.Read(b[:]); err != nil {
+		return "", fmt.Errorf("pick email signup phone prefix: %w", err)
+	}
+	idx := binary.LittleEndian.Uint64(b[:]) % uint64(len(prefixes))
+	return prefixes[idx], nil
+}
+
 func phoneChangeHash() (string, error) {
 	var raw [8]byte
 	if _, err := rand.Read(raw[:]); err != nil {

internal/app/account/service.go

@@ -55,6 +55,10 @@ type Service struct {
 	// 验证码走 loginEmailSender 发到解码出的邮箱；非 888 号码一律拒绝——本服务器没有真实
 	// 短信通道，放行会让账号的邮箱身份绑定被绕过（见迁移前的密码找回验证码漏洞教训）。
 	emailSignupEnabled bool
+	// emailSignupPhonePrefixes 是改绑邮箱时随机挑选的账号展示号码号段前缀
+	// 列表（domain.NewEmailSignupDisplayPhone），与 auth.Service 的同名字段
+	// 同一份服务端配置来源。为空时退回默认 "888"。
+	emailSignupPhonePrefixes []string
 }
 
 // ServiceOption 调整 account 服务依赖。
@@ -163,6 +167,14 @@ func WithEmailSignup(enabled bool) ServiceOption {
 	}
 }
 
+// WithEmailSignupPhonePrefixes 设置改绑邮箱时展示号码随机挑选的号段前缀列表
+// （见 emailSignupPhonePrefixes 字段注释）。
+func WithEmailSignupPhonePrefixes(prefixes []string) ServiceOption {
+	return func(s *Service) {
+		s.emailSignupPhonePrefixes = prefixes
+	}
+}
+
 // NewService 创建 account 服务。
 func NewService(passwords store.PasswordStore, opts ...ServiceOption) *Service {
 	s := &Service{