feat(admin): 新增 CRS 同步预览和账号选择功能

- 后端新增 PreviewFromCRS 接口，允许用户先预览 CRS 中的账号
- 后端支持在同步时选择特定账号，不选中的账号将被跳过
- 前端重构 SyncFromCrsModal 为三步向导：输入凭据 → 预览账号 → 执行同步
- 改进表单无障碍性：添加 for/id 关联和 required 属性
- 修复 Back 按钮返回时的状态清理
- 新增 buildSelectedSet 和 shouldCreateAccount 的单元测试
- 完整的向后兼容性：旧客户端不发送 selected_account_ids 时行为不变

backend/internal/handler/admin/account_handler.go

@@ -424,10 +424,17 @@ type TestAccountRequest struct {
 }
 
 type SyncFromCRSRequest struct {
-	BaseURL     string `json:"base_url" binding:"required"`
-	Username    string `json:"username" binding:"required"`
-	Password    string `json:"password" binding:"required"`
-	SyncProxies *bool  `json:"sync_proxies"`
+	BaseURL            string   `json:"base_url" binding:"required"`
+	Username           string   `json:"username" binding:"required"`
+	Password           string   `json:"password" binding:"required"`
+	SyncProxies        *bool    `json:"sync_proxies"`
+	SelectedAccountIDs []string `json:"selected_account_ids"`
+}
+
+type PreviewFromCRSRequest struct {
+	BaseURL  string `json:"base_url" binding:"required"`
+	Username string `json:"username" binding:"required"`
+	Password string `json:"password" binding:"required"`
 }
 
 // Test handles testing account connectivity with SSE streaming
@@ -466,10 +473,11 @@ func (h *AccountHandler) SyncFromCRS(c *gin.Context) {
 	}
 
 	result, err := h.crsSyncService.SyncFromCRS(c.Request.Context(), service.SyncFromCRSInput{
-		BaseURL:     req.BaseURL,
-		Username:    req.Username,
-		Password:    req.Password,
-		SyncProxies: syncProxies,
+		BaseURL:            req.BaseURL,
+		Username:           req.Username,
+		Password:           req.Password,
+		SyncProxies:        syncProxies,
+		SelectedAccountIDs: req.SelectedAccountIDs,
 	})
 	if err != nil {
 		// Provide detailed error message for CRS sync failures
@@ -480,6 +488,28 @@ func (h *AccountHandler) SyncFromCRS(c *gin.Context) {
 	response.Success(c, result)
 }
 
+// PreviewFromCRS handles previewing accounts from CRS before sync
+// POST /api/v1/admin/accounts/sync/crs/preview
+func (h *AccountHandler) PreviewFromCRS(c *gin.Context) {
+	var req PreviewFromCRSRequest
+	if err := c.ShouldBindJSON(&req); err != nil {
+		response.BadRequest(c, "Invalid request: "+err.Error())
+		return
+	}
+
+	result, err := h.crsSyncService.PreviewFromCRS(c.Request.Context(), service.SyncFromCRSInput{
+		BaseURL:  req.BaseURL,
+		Username: req.Username,
+		Password: req.Password,
+	})
+	if err != nil {
+		response.InternalError(c, "CRS preview failed: "+err.Error())
+		return
+	}
+
+	response.Success(c, result)
+}
+
 // Refresh handles refreshing account credentials
 // POST /api/v1/admin/accounts/:id/refresh
 func (h *AccountHandler) Refresh(c *gin.Context) {

backend/internal/repository/account_repo.go

@@ -282,6 +282,34 @@ func (r *accountRepository) GetByCRSAccountID(ctx context.Context, crsAccountID
 	return &accounts[0], nil
 }
 
+func (r *accountRepository) ListCRSAccountIDs(ctx context.Context) (map[string]int64, error) {
+	rows, err := r.sql.QueryContext(ctx, `
+		SELECT id, extra->>'crs_account_id'
+		FROM accounts
+		WHERE deleted_at IS NULL
+			AND extra->>'crs_account_id' IS NOT NULL
+			AND extra->>'crs_account_id' != ''
+	`)
+	if err != nil {
+		return nil, err
+	}
+	defer func() { _ = rows.Close() }()
+
+	result := make(map[string]int64)
+	for rows.Next() {
+		var id int64
+		var crsID string
+		if err := rows.Scan(&id, &crsID); err != nil {
+			return nil, err
+		}
+		result[crsID] = id
+	}
+	if err := rows.Err(); err != nil {
+		return nil, err
+	}
+	return result, nil
+}
+
 func (r *accountRepository) Update(ctx context.Context, account *service.Account) error {
 	if account == nil {
 		return nil

backend/internal/server/routes/admin.go

@@ -209,6 +209,7 @@ func registerAccountRoutes(admin *gin.RouterGroup, h *handler.Handlers) {
 		accounts.GET("/:id", h.Admin.Account.GetByID)
 		accounts.POST("", h.Admin.Account.Create)
 		accounts.POST("/sync/crs", h.Admin.Account.SyncFromCRS)
+		accounts.POST("/sync/crs/preview", h.Admin.Account.PreviewFromCRS)
 		accounts.PUT("/:id", h.Admin.Account.Update)
 		accounts.DELETE("/:id", h.Admin.Account.Delete)
 		accounts.POST("/:id/test", h.Admin.Account.Test)

backend/internal/service/account_service.go

@@ -25,6 +25,9 @@ type AccountRepository interface {
 	// GetByCRSAccountID finds an account previously synced from CRS.
 	// Returns (nil, nil) if not found.
 	GetByCRSAccountID(ctx context.Context, crsAccountID string) (*Account, error)
+	// ListCRSAccountIDs returns a map of crs_account_id -> local account ID
+	// for all accounts that have been synced from CRS.
+	ListCRSAccountIDs(ctx context.Context) (map[string]int64, error)
 	Update(ctx context.Context, account *Account) error
 	Delete(ctx context.Context, id int64) error
 

backend/internal/service/account_service_delete_test.go

@@ -54,6 +54,10 @@ func (s *accountRepoStub) GetByCRSAccountID(ctx context.Context, crsAccountID st
 	panic("unexpected GetByCRSAccountID call")
 }
 
+func (s *accountRepoStub) ListCRSAccountIDs(ctx context.Context) (map[string]int64, error) {
+	panic("unexpected ListCRSAccountIDs call")
+}
+
 func (s *accountRepoStub) Update(ctx context.Context, account *Account) error {
 	panic("unexpected Update call")
 }

backend/internal/service/crs_sync_helpers_test.go

+package service
+
+import (
+	"testing"
+)
+
+func TestBuildSelectedSet(t *testing.T) {
+	tests := []struct {
+		name     string
+		ids      []string
+		wantNil  bool
+		wantSize int
+	}{
+		{
+			name:    "nil input returns nil (backward compatible: create all)",
+			ids:     nil,
+			wantNil: true,
+		},
+		{
+			name:     "empty slice returns empty map (create none)",
+			ids:      []string{},
+			wantNil:  false,
+			wantSize: 0,
+		},
+		{
+			name:     "single ID",
+			ids:      []string{"abc-123"},
+			wantNil:  false,
+			wantSize: 1,
+		},
+		{
+			name:     "multiple IDs",
+			ids:      []string{"a", "b", "c"},
+			wantNil:  false,
+			wantSize: 3,
+		},
+		{
+			name:     "duplicate IDs are deduplicated",
+			ids:      []string{"a", "a", "b"},
+			wantNil:  false,
+			wantSize: 2,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got := buildSelectedSet(tt.ids)
+			if tt.wantNil {
+				if got != nil {
+					t.Errorf("buildSelectedSet(%v) = %v, want nil", tt.ids, got)
+				}
+				return
+			}
+			if got == nil {
+				t.Fatalf("buildSelectedSet(%v) = nil, want non-nil map", tt.ids)
+			}
+			if len(got) != tt.wantSize {
+				t.Errorf("buildSelectedSet(%v) has %d entries, want %d", tt.ids, len(got), tt.wantSize)
+			}
+			// Verify all unique IDs are present
+			for _, id := range tt.ids {
+				if _, ok := got[id]; !ok {
+					t.Errorf("buildSelectedSet(%v) missing key %q", tt.ids, id)
+				}
+			}
+		})
+	}
+}
+
+func TestShouldCreateAccount(t *testing.T) {
+	tests := []struct {
+		name        string
+		crsID       string
+		selectedSet map[string]struct{}
+		want        bool
+	}{
+		{
+			name:        "nil set allows all (backward compatible)",
+			crsID:       "any-id",
+			selectedSet: nil,
+			want:        true,
+		},
+		{
+			name:        "empty set blocks all",
+			crsID:       "any-id",
+			selectedSet: map[string]struct{}{},
+			want:        false,
+		},
+		{
+			name:        "ID in set is allowed",
+			crsID:       "abc-123",
+			selectedSet: map[string]struct{}{"abc-123": {}, "def-456": {}},
+			want:        true,
+		},
+		{
+			name:        "ID not in set is blocked",
+			crsID:       "xyz-789",
+			selectedSet: map[string]struct{}{"abc-123": {}, "def-456": {}},
+			want:        false,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got := shouldCreateAccount(tt.crsID, tt.selectedSet)
+			if got != tt.want {
+				t.Errorf("shouldCreateAccount(%q, %v) = %v, want %v",
+					tt.crsID, tt.selectedSet, got, tt.want)
+			}
+		})
+	}
+}

backend/internal/service/crs_sync_service.go

@@ -45,10 +45,11 @@ func NewCRSSyncService(
 }
 
 type SyncFromCRSInput struct {
-	BaseURL     string
-	Username    string
-	Password    string
-	SyncProxies bool
+	BaseURL            string
+	Username           string
+	Password           string
+	SyncProxies        bool
+	SelectedAccountIDs []string // if non-empty, only create new accounts with these CRS IDs
 }
 
 type SyncFromCRSItemResult struct {
@@ -190,25 +191,27 @@ type crsGeminiAPIKeyAccount struct {
 	Extra       map[string]any `json:"extra"`
 }
 
-func (s *CRSSyncService) SyncFromCRS(ctx context.Context, input SyncFromCRSInput) (*SyncFromCRSResult, error) {
+// fetchCRSExport validates the connection parameters, authenticates with CRS,
+// and returns the exported accounts. Shared by SyncFromCRS and PreviewFromCRS.
+func (s *CRSSyncService) fetchCRSExport(ctx context.Context, baseURL, username, password string) (*crsExportResponse, error) {
 	if s.cfg == nil {
 		return nil, errors.New("config is not available")
 	}
-	baseURL := strings.TrimSpace(input.BaseURL)
+	normalizedURL := strings.TrimSpace(baseURL)
 	if s.cfg.Security.URLAllowlist.Enabled {
-		normalized, err := normalizeBaseURL(baseURL, s.cfg.Security.URLAllowlist.CRSHosts, s.cfg.Security.URLAllowlist.AllowPrivateHosts)
+		normalized, err := normalizeBaseURL(normalizedURL, s.cfg.Security.URLAllowlist.CRSHosts, s.cfg.Security.URLAllowlist.AllowPrivateHosts)
 		if err != nil {
 			return nil, err
 		}
-		baseURL = normalized
+		normalizedURL = normalized
 	} else {
-		normalized, err := urlvalidator.ValidateURLFormat(baseURL, s.cfg.Security.URLAllowlist.AllowInsecureHTTP)
+		normalized, err := urlvalidator.ValidateURLFormat(normalizedURL, s.cfg.Security.URLAllowlist.AllowInsecureHTTP)
 		if err != nil {
 			return nil, fmt.Errorf("invalid base_url: %w", err)
 		}
-		baseURL = normalized
+		normalizedURL = normalized
 	}
-	if strings.TrimSpace(input.Username) == "" || strings.TrimSpace(input.Password) == "" {
+	if strings.TrimSpace(username) == "" || strings.TrimSpace(password) == "" {
 		return nil, errors.New("username and password are required")
 	}
 
@@ -221,12 +224,16 @@ func (s *CRSSyncService) SyncFromCRS(ctx context.Context, input SyncFromCRSInput
 		client = &http.Client{Timeout: 20 * time.Second}
 	}
 
-	adminToken, err := crsLogin(ctx, client, baseURL, input.Username, input.Password)
+	adminToken, err := crsLogin(ctx, client, normalizedURL, username, password)
 	if err != nil {
 		return nil, err
 	}
 
-	exported, err := crsExportAccounts(ctx, client, baseURL, adminToken)
+	return crsExportAccounts(ctx, client, normalizedURL, adminToken)
+}
+
+func (s *CRSSyncService) SyncFromCRS(ctx context.Context, input SyncFromCRSInput) (*SyncFromCRSResult, error) {
+	exported, err := s.fetchCRSExport(ctx, input.BaseURL, input.Username, input.Password)
 	if err != nil {
 		return nil, err
 	}
@@ -241,6 +248,8 @@ func (s *CRSSyncService) SyncFromCRS(ctx context.Context, input SyncFromCRSInput
 		),
 	}
 
+	selectedSet := buildSelectedSet(input.SelectedAccountIDs)
+
 	var proxies []Proxy
 	if input.SyncProxies {
 		proxies, _ = s.proxyRepo.ListActive(ctx)
@@ -329,6 +338,13 @@ func (s *CRSSyncService) SyncFromCRS(ctx context.Context, input SyncFromCRSInput
 		}
 
 		if existing == nil {
+			if !shouldCreateAccount(src.ID, selectedSet) {
+				item.Action = "skipped"
+				item.Error = "not selected"
+				result.Skipped++
+				result.Items = append(result.Items, item)
+				continue
+			}
 			account := &Account{
 				Name:        defaultName(src.Name, src.ID),
 				Platform:    PlatformAnthropic,
@@ -446,6 +462,13 @@ func (s *CRSSyncService) SyncFromCRS(ctx context.Context, input SyncFromCRSInput
 		}
 
 		if existing == nil {
+			if !shouldCreateAccount(src.ID, selectedSet) {
+				item.Action = "skipped"
+				item.Error = "not selected"
+				result.Skipped++
+				result.Items = append(result.Items, item)
+				continue
+			}
 			account := &Account{
 				Name:        defaultName(src.Name, src.ID),
 				Platform:    PlatformAnthropic,
@@ -569,6 +592,13 @@ func (s *CRSSyncService) SyncFromCRS(ctx context.Context, input SyncFromCRSInput
 		}
 
 		if existing == nil {
+			if !shouldCreateAccount(src.ID, selectedSet) {
+				item.Action = "skipped"
+				item.Error = "not selected"
+				result.Skipped++
+				result.Items = append(result.Items, item)
+				continue
+			}
 			account := &Account{
 				Name:        defaultName(src.Name, src.ID),
 				Platform:    PlatformOpenAI,
@@ -690,6 +720,13 @@ func (s *CRSSyncService) SyncFromCRS(ctx context.Context, input SyncFromCRSInput
 		}
 
 		if existing == nil {
+			if !shouldCreateAccount(src.ID, selectedSet) {
+				item.Action = "skipped"
+				item.Error = "not selected"
+				result.Skipped++
+				result.Items = append(result.Items, item)
+				continue
+			}
 			account := &Account{
 				Name:        defaultName(src.Name, src.ID),
 				Platform:    PlatformOpenAI,
@@ -798,6 +835,13 @@ func (s *CRSSyncService) SyncFromCRS(ctx context.Context, input SyncFromCRSInput
 		}
 
 		if existing == nil {
+			if !shouldCreateAccount(src.ID, selectedSet) {
+				item.Action = "skipped"
+				item.Error = "not selected"
+				result.Skipped++
+				result.Items = append(result.Items, item)
+				continue
+			}
 			account := &Account{
 				Name:        defaultName(src.Name, src.ID),
 				Platform:    PlatformGemini,
@@ -909,6 +953,13 @@ func (s *CRSSyncService) SyncFromCRS(ctx context.Context, input SyncFromCRSInput
 		}
 
 		if existing == nil {
+			if !shouldCreateAccount(src.ID, selectedSet) {
+				item.Action = "skipped"
+				item.Error = "not selected"
+				result.Skipped++
+				result.Items = append(result.Items, item)
+				continue
+			}
 			account := &Account{
 				Name:        defaultName(src.Name, src.ID),
 				Platform:    PlatformGemini,
@@ -1253,3 +1304,102 @@ func (s *CRSSyncService) refreshOAuthToken(ctx context.Context, account *Account
 
 	return newCredentials
 }
+
+// buildSelectedSet converts a slice of selected CRS account IDs to a set for O(1) lookup.
+// Returns nil if ids is nil (field not sent → backward compatible: create all).
+// Returns an empty map if ids is non-nil but empty (user selected none → create none).
+func buildSelectedSet(ids []string) map[string]struct{} {
+	if ids == nil {
+		return nil
+	}
+	set := make(map[string]struct{}, len(ids))
+	for _, id := range ids {
+		set[id] = struct{}{}
+	}
+	return set
+}
+
+// shouldCreateAccount checks if a new CRS account should be created based on user selection.
+// Returns true if selectedSet is nil (backward compatible: create all) or if crsID is in the set.
+func shouldCreateAccount(crsID string, selectedSet map[string]struct{}) bool {
+	if selectedSet == nil {
+		return true
+	}
+	_, ok := selectedSet[crsID]
+	return ok
+}
+
+// PreviewFromCRSResult contains the preview of accounts from CRS before sync.
+type PreviewFromCRSResult struct {
+	NewAccounts      []CRSPreviewAccount `json:"new_accounts"`
+	ExistingAccounts []CRSPreviewAccount `json:"existing_accounts"`
+}
+
+// CRSPreviewAccount represents a single account in the preview result.
+type CRSPreviewAccount struct {
+	CRSAccountID string `json:"crs_account_id"`
+	Kind         string `json:"kind"`
+	Name         string `json:"name"`
+	Platform     string `json:"platform"`
+	Type         string `json:"type"`
+}
+
+// PreviewFromCRS connects to CRS, fetches all accounts, and classifies them
+// as new or existing by batch-querying local crs_account_id mappings.
+func (s *CRSSyncService) PreviewFromCRS(ctx context.Context, input SyncFromCRSInput) (*PreviewFromCRSResult, error) {
+	exported, err := s.fetchCRSExport(ctx, input.BaseURL, input.Username, input.Password)
+	if err != nil {
+		return nil, err
+	}
+
+	// Batch query all existing CRS account IDs
+	existingCRSIDs, err := s.accountRepo.ListCRSAccountIDs(ctx)
+	if err != nil {
+		return nil, fmt.Errorf("failed to list existing CRS accounts: %w", err)
+	}
+
+	result := &PreviewFromCRSResult{
+		NewAccounts:      make([]CRSPreviewAccount, 0),
+		ExistingAccounts: make([]CRSPreviewAccount, 0),
+	}
+
+	classify := func(crsID, kind, name, platform, accountType string) {
+		preview := CRSPreviewAccount{
+			CRSAccountID: crsID,
+			Kind:         kind,
+			Name:         defaultName(name, crsID),
+			Platform:     platform,
+			Type:         accountType,
+		}
+		if _, exists := existingCRSIDs[crsID]; exists {
+			result.ExistingAccounts = append(result.ExistingAccounts, preview)
+		} else {
+			result.NewAccounts = append(result.NewAccounts, preview)
+		}
+	}
+
+	for _, src := range exported.Data.ClaudeAccounts {
+		authType := strings.TrimSpace(src.AuthType)
+		if authType == "" {
+			authType = AccountTypeOAuth
+		}
+		classify(src.ID, src.Kind, src.Name, PlatformAnthropic, authType)
+	}
+	for _, src := range exported.Data.ClaudeConsoleAccounts {
+		classify(src.ID, src.Kind, src.Name, PlatformAnthropic, AccountTypeAPIKey)
+	}
+	for _, src := range exported.Data.OpenAIOAuthAccounts {
+		classify(src.ID, src.Kind, src.Name, PlatformOpenAI, AccountTypeOAuth)
+	}
+	for _, src := range exported.Data.OpenAIResponsesAccounts {
+		classify(src.ID, src.Kind, src.Name, PlatformOpenAI, AccountTypeAPIKey)
+	}
+	for _, src := range exported.Data.GeminiOAuthAccounts {
+		classify(src.ID, src.Kind, src.Name, PlatformGemini, AccountTypeOAuth)
+	}
+	for _, src := range exported.Data.GeminiAPIKeyAccounts {
+		classify(src.ID, src.Kind, src.Name, PlatformGemini, AccountTypeAPIKey)
+	}
+
+	return result, nil
+}

backend/internal/service/gateway_multiplatform_test.go

@@ -77,6 +77,9 @@ func (m *mockAccountRepoForPlatform) Create(ctx context.Context, account *Accoun
 func (m *mockAccountRepoForPlatform) GetByCRSAccountID(ctx context.Context, crsAccountID string) (*Account, error) {
 	return nil, nil
 }
+func (m *mockAccountRepoForPlatform) ListCRSAccountIDs(ctx context.Context) (map[string]int64, error) {
+	return nil, nil
+}
 func (m *mockAccountRepoForPlatform) Update(ctx context.Context, account *Account) error {
 	return nil
 }

backend/internal/service/gemini_multiplatform_test.go

@@ -66,6 +66,9 @@ func (m *mockAccountRepoForGemini) Create(ctx context.Context, account *Account)
 func (m *mockAccountRepoForGemini) GetByCRSAccountID(ctx context.Context, crsAccountID string) (*Account, error) {
 	return nil, nil
 }
+func (m *mockAccountRepoForGemini) ListCRSAccountIDs(ctx context.Context) (map[string]int64, error) {
+	return nil, nil
+}
 func (m *mockAccountRepoForGemini) Update(ctx context.Context, account *Account) error { return nil }
 func (m *mockAccountRepoForGemini) Delete(ctx context.Context, id int64) error         { return nil }
 func (m *mockAccountRepoForGemini) List(ctx context.Context, params pagination.PaginationParams) ([]Account, *pagination.PaginationResult, error) {

frontend/src/api/admin/accounts.ts

@@ -327,11 +327,34 @@ export async function getAvailableModels(id: number): Promise<ClaudeModel[]> {
   return data
 }
 
+export interface CRSPreviewAccount {
+  crs_account_id: string
+  kind: string
+  name: string
+  platform: string
+  type: string
+}
+
+export interface PreviewFromCRSResult {
+  new_accounts: CRSPreviewAccount[]
+  existing_accounts: CRSPreviewAccount[]
+}
+
+export async function previewFromCrs(params: {
+  base_url: string
+  username: string
+  password: string
+}): Promise<PreviewFromCRSResult> {
+  const { data } = await apiClient.post<PreviewFromCRSResult>('/admin/accounts/sync/crs/preview', params)
+  return data
+}
+
 export async function syncFromCrs(params: {
   base_url: string
   username: string
   password: string
   sync_proxies?: boolean
+  selected_account_ids?: string[]
 }): Promise<{
   created: number
   updated: number
@@ -345,7 +368,19 @@ export async function syncFromCrs(params: {
     error?: string
   }>
 }> {
-  const { data } = await apiClient.post('/admin/accounts/sync/crs', params)
+  const { data } = await apiClient.post<{
+    created: number
+    updated: number
+    skipped: number
+    failed: number
+    items: Array<{
+      crs_account_id: string
+      kind: string
+      name: string
+      action: string
+      error?: string
+    }>
+  }>('/admin/accounts/sync/crs', params)
   return data
 }
 
@@ -442,6 +477,7 @@ export const accountsAPI = {
   batchCreate,
   batchUpdateCredentials,
   bulkUpdate,
+  previewFromCrs,
   syncFromCrs,
   exportData,
   importData,

frontend/src/components/account/SyncFromCrsModal.vue

@@ -6,15 +6,20 @@
     close-on-click-outside
     @close="handleClose"
   >
-    <form id="sync-from-crs-form" class="space-y-4" @submit.prevent="handleSync">
+    <!-- Step 1: Input credentials -->
+    <form
+      v-if="currentStep === 'input'"
+      id="sync-from-crs-form"
+      class="space-y-4"
+      @submit.prevent="handlePreview"
+    >
       <div class="text-sm text-gray-600 dark:text-dark-300">
         {{ t('admin.accounts.syncFromCrsDesc') }}
       </div>
       <div
         class="rounded-lg bg-gray-50 p-3 text-xs text-gray-500 dark:bg-dark-700/60 dark:text-dark-400"
       >
-        已有账号仅同步 CRS
-        返回的字段，缺失字段保持原值；凭据按键合并，不会清空未下发的键；未勾选"同步代理"时保留原有代理。
+        {{ t('admin.accounts.crsUpdateBehaviorNote') }}
       </div>
       <div
         class="rounded-lg border border-amber-200 bg-amber-50 p-3 text-xs text-amber-600 dark:border-amber-800 dark:bg-amber-900/20 dark:text-amber-400"
@@ -24,26 +29,30 @@
 
       <div class="grid grid-cols-1 gap-4">
         <div>
-          <label class="input-label">{{ t('admin.accounts.crsBaseUrl') }}</label>
+          <label for="crs-base-url" class="input-label">{{ t('admin.accounts.crsBaseUrl') }}</label>
           <input
+            id="crs-base-url"
             v-model="form.base_url"
             type="text"
             class="input"
+            required
             :placeholder="t('admin.accounts.crsBaseUrlPlaceholder')"
           />
         </div>
 
         <div class="grid grid-cols-1 gap-4 sm:grid-cols-2">
           <div>
-            <label class="input-label">{{ t('admin.accounts.crsUsername') }}</label>
-            <input v-model="form.username" type="text" class="input" autocomplete="username" />
+            <label for="crs-username" class="input-label">{{ t('admin.accounts.crsUsername') }}</label>
+            <input id="crs-username" v-model="form.username" type="text" class="input" required autocomplete="username" />
           </div>
           <div>
-            <label class="input-label">{{ t('admin.accounts.crsPassword') }}</label>
+            <label for="crs-password" class="input-label">{{ t('admin.accounts.crsPassword') }}</label>
             <input
+              id="crs-password"
               v-model="form.password"
               type="password"
               class="input"
+              required
               autocomplete="current-password"
             />
           </div>
@@ -58,9 +67,101 @@
           {{ t('admin.accounts.syncProxies') }}
         </label>
       </div>
+    </form>
+
+    <!-- Step 2: Preview & select -->
+    <div v-else-if="currentStep === 'preview' && previewResult" class="space-y-4">
+      <!-- Existing accounts (read-only info) -->
+      <div
+        v-if="previewResult.existing_accounts.length"
+        class="rounded-lg bg-gray-50 p-3 dark:bg-dark-700/60"
+      >
+        <div class="mb-2 text-sm font-medium text-gray-700 dark:text-dark-300">
+          {{ t('admin.accounts.crsExistingAccounts') }}
+          <span class="ml-1 text-xs text-gray-400">({{ previewResult.existing_accounts.length }})</span>
+        </div>
+        <div class="max-h-32 overflow-auto text-xs text-gray-500 dark:text-dark-400">
+          <div
+            v-for="acc in previewResult.existing_accounts"
+            :key="acc.crs_account_id"
+            class="flex items-center gap-2 py-0.5"
+          >
+            <span
+              class="inline-block rounded bg-blue-100 px-1.5 py-0.5 text-[10px] font-medium text-blue-700 dark:bg-blue-900/30 dark:text-blue-400"
+            >{{ acc.platform }} / {{ acc.type }}</span>
+            <span class="truncate">{{ acc.name }}</span>
+          </div>
+        </div>
+      </div>
+
+      <!-- New accounts (selectable) -->
+      <div v-if="previewResult.new_accounts.length">
+        <div class="mb-2 flex items-center justify-between">
+          <div class="text-sm font-medium text-gray-900 dark:text-white">
+            {{ t('admin.accounts.crsNewAccounts') }}
+            <span class="ml-1 text-xs text-gray-400">({{ previewResult.new_accounts.length }})</span>
+          </div>
+          <div class="flex gap-2">
+            <button
+              type="button"
+              class="text-xs text-blue-600 hover:text-blue-700 dark:text-blue-400"
+              @click="selectAll"
+            >{{ t('admin.accounts.crsSelectAll') }}</button>
+            <button
+              type="button"
+              class="text-xs text-gray-500 hover:text-gray-600 dark:text-gray-400"
+              @click="selectNone"
+            >{{ t('admin.accounts.crsSelectNone') }}</button>
+          </div>
+        </div>
+        <div
+          class="max-h-48 overflow-auto rounded-lg border border-gray-200 p-2 dark:border-dark-600"
+        >
+          <label
+            v-for="acc in previewResult.new_accounts"
+            :key="acc.crs_account_id"
+            class="flex cursor-pointer items-center gap-2 rounded px-2 py-1.5 hover:bg-gray-50 dark:hover:bg-dark-700/40"
+          >
+            <input
+              type="checkbox"
+              :checked="selectedIds.has(acc.crs_account_id)"
+              class="rounded border-gray-300 dark:border-dark-600"
+              @change="toggleSelect(acc.crs_account_id)"
+            />
+            <span
+              class="inline-block rounded bg-green-100 px-1.5 py-0.5 text-[10px] font-medium text-green-700 dark:bg-green-900/30 dark:text-green-400"
+            >{{ acc.platform }} / {{ acc.type }}</span>
+            <span class="truncate text-sm text-gray-700 dark:text-dark-300">{{ acc.name }}</span>
+          </label>
+        </div>
+        <div class="mt-1 text-xs text-gray-400">
+          {{ t('admin.accounts.crsSelectedCount', { count: selectedIds.size }) }}
+        </div>
+      </div>
+
+      <!-- Sync options summary -->
+      <div class="flex items-center gap-2 text-xs text-gray-500 dark:text-dark-400">
+        <span>{{ t('admin.accounts.syncProxies') }}:</span>
+        <span :class="form.sync_proxies ? 'text-green-600 dark:text-green-400' : 'text-gray-400 dark:text-dark-500'">
+          {{ form.sync_proxies ? t('common.yes') : t('common.no') }}
+        </span>
+      </div>
 
+      <!-- No new accounts -->
+      <div
+        v-if="!previewResult.new_accounts.length"
+        class="rounded-lg bg-gray-50 p-4 text-center text-sm text-gray-500 dark:bg-dark-700/60 dark:text-dark-400"
+      >
+        {{ t('admin.accounts.crsNoNewAccounts') }}
+        <span v-if="previewResult.existing_accounts.length">
+          {{ t('admin.accounts.crsWillUpdate', { count: previewResult.existing_accounts.length }) }}
+        </span>
+      </div>
+    </div>
+
+    <!-- Step 3: Result -->
+    <div v-else-if="currentStep === 'result' && result" class="space-y-4">
       <div
-        v-if="result"
         class="space-y-2 rounded-xl border border-gray-200 p-4 dark:border-dark-700"
       >
         <div class="text-sm font-medium text-gray-900 dark:text-white">
@@ -84,21 +185,56 @@
           </div>
         </div>
       </div>
-    </form>
+    </div>
 
     <template #footer>
       <div class="flex justify-end gap-3">
-        <button class="btn btn-secondary" type="button" :disabled="syncing" @click="handleClose">
-          {{ t('common.cancel') }}
-        </button>
-        <button
-          class="btn btn-primary"
-          type="submit"
-          form="sync-from-crs-form"
-          :disabled="syncing"
-        >
-          {{ syncing ? t('admin.accounts.syncing') : t('admin.accounts.syncNow') }}
-        </button>
+        <!-- Step 1: Input -->
+        <template v-if="currentStep === 'input'">
+          <button
+            class="btn btn-secondary"
+            type="button"
+            :disabled="previewing"
+            @click="handleClose"
+          >
+            {{ t('common.cancel') }}
+          </button>
+          <button
+            class="btn btn-primary"
+            type="submit"
+            form="sync-from-crs-form"
+            :disabled="previewing"
+          >
+            {{ previewing ? t('admin.accounts.crsPreviewing') : t('admin.accounts.crsPreview') }}
+          </button>
+        </template>
+
+        <!-- Step 2: Preview -->
+        <template v-else-if="currentStep === 'preview'">
+          <button
+            class="btn btn-secondary"
+            type="button"
+            :disabled="syncing"
+            @click="handleBack"
+          >
+            {{ t('admin.accounts.crsBack') }}
+          </button>
+          <button
+            class="btn btn-primary"
+            type="button"
+            :disabled="syncing || hasNewButNoneSelected"
+            @click="handleSync"
+          >
+            {{ syncing ? t('admin.accounts.syncing') : t('admin.accounts.syncNow') }}
+          </button>
+        </template>
+
+        <!-- Step 3: Result -->
+        <template v-else-if="currentStep === 'result'">
+          <button class="btn btn-secondary" type="button" @click="handleClose">
+            {{ t('common.close') }}
+          </button>
+        </template>
       </div>
     </template>
   </BaseDialog>
@@ -110,6 +246,7 @@ import { useI18n } from 'vue-i18n'
 import BaseDialog from '@/components/common/BaseDialog.vue'
 import { useAppStore } from '@/stores/app'
 import { adminAPI } from '@/api/admin'
+import type { PreviewFromCRSResult } from '@/api/admin/accounts'
 
 interface Props {
   show: boolean
@@ -126,7 +263,12 @@ const emit = defineEmits<Emits>()
 const { t } = useI18n()
 const appStore = useAppStore()
 
+type Step = 'input' | 'preview' | 'result'
+const currentStep = ref<Step>('input')
+const previewing = ref(false)
 const syncing = ref(false)
+const previewResult = ref<PreviewFromCRSResult | null>(null)
+const selectedIds = ref(new Set<string>())
 const result = ref<Awaited<ReturnType<typeof adminAPI.accounts.syncFromCrs>> | null>(null)
 
 const form = reactive({
@@ -136,28 +278,90 @@ const form = reactive({
   sync_proxies: true
 })
 
+const hasNewButNoneSelected = computed(() => {
+  if (!previewResult.value) return false
+  return previewResult.value.new_accounts.length > 0 && selectedIds.value.size === 0
+})
+
 const errorItems = computed(() => {
   if (!result.value?.items) return []
-  return result.value.items.filter((i) => i.action === 'failed' || i.action === 'skipped')
+  return result.value.items.filter(
+    (i) => i.action === 'failed' || (i.action === 'skipped' && i.error !== 'not selected')
+  )
 })
 
 watch(
   () => props.show,
   (open) => {
     if (open) {
+      currentStep.value = 'input'
+      previewResult.value = null
+      selectedIds.value = new Set()
       result.value = null
+      form.base_url = ''
+      form.username = ''
+      form.password = ''
+      form.sync_proxies = true
     }
   }
 )
 
 const handleClose = () => {
-  // 防止在同步进行中关闭对话框
-  if (syncing.value) {
+  if (syncing.value || previewing.value) {
     return
   }
   emit('close')
 }
 
+const handleBack = () => {
+  currentStep.value = 'input'
+  previewResult.value = null
+  selectedIds.value = new Set()
+}
+
+const selectAll = () => {
+  if (!previewResult.value) return
+  selectedIds.value = new Set(previewResult.value.new_accounts.map((a) => a.crs_account_id))
+}
+
+const selectNone = () => {
+  selectedIds.value = new Set()
+}
+
+const toggleSelect = (id: string) => {
+  const s = new Set(selectedIds.value)
+  if (s.has(id)) {
+    s.delete(id)
+  } else {
+    s.add(id)
+  }
+  selectedIds.value = s
+}
+
+const handlePreview = async () => {
+  if (!form.base_url.trim() || !form.username.trim() || !form.password.trim()) {
+    appStore.showError(t('admin.accounts.syncMissingFields'))
+    return
+  }
+
+  previewing.value = true
+  try {
+    const res = await adminAPI.accounts.previewFromCrs({
+      base_url: form.base_url.trim(),
+      username: form.username.trim(),
+      password: form.password
+    })
+    previewResult.value = res
+    // Auto-select all new accounts
+    selectedIds.value = new Set(res.new_accounts.map((a) => a.crs_account_id))
+    currentStep.value = 'preview'
+  } catch (error: any) {
+    appStore.showError(error?.message || t('admin.accounts.crsPreviewFailed'))
+  } finally {
+    previewing.value = false
+  }
+}
+
 const handleSync = async () => {
   if (!form.base_url.trim() || !form.username.trim() || !form.password.trim()) {
     appStore.showError(t('admin.accounts.syncMissingFields'))
@@ -170,16 +374,18 @@ const handleSync = async () => {
       base_url: form.base_url.trim(),
       username: form.username.trim(),
       password: form.password,
-      sync_proxies: form.sync_proxies
+      sync_proxies: form.sync_proxies,
+      selected_account_ids: [...selectedIds.value]
     })
     result.value = res
+    currentStep.value = 'result'
 
     if (res.failed > 0) {
       appStore.showError(t('admin.accounts.syncCompletedWithErrors', res))
     } else {
       appStore.showSuccess(t('admin.accounts.syncCompleted', res))
-      emit('synced')
     }
+    emit('synced')
   } catch (error: any) {
     appStore.showError(error?.message || t('admin.accounts.syncFailed'))
   } finally {

frontend/src/i18n/locales/en.ts

@@ -1309,10 +1309,23 @@ export default {
       syncResult: 'Sync Result',
       syncResultSummary: 'Created {created}, updated {updated}, skipped {skipped}, failed {failed}',
       syncErrors: 'Errors / Skipped Details',
-      syncCompleted: 'Sync completed: created {created}, updated {updated}',
+      syncCompleted: 'Sync completed: created {created}, updated {updated}, skipped {skipped}',
       syncCompletedWithErrors:
-        'Sync completed with errors: failed {failed} (created {created}, updated {updated})',
+        'Sync completed with errors: failed {failed} (created {created}, updated {updated}, skipped {skipped})',
       syncFailed: 'Sync failed',
+      crsPreview: 'Preview',
+      crsPreviewing: 'Previewing...',
+      crsPreviewFailed: 'Preview failed',
+      crsExistingAccounts: 'Existing accounts (will be updated)',
+      crsNewAccounts: 'New accounts (select to sync)',
+      crsSelectAll: 'Select all',
+      crsSelectNone: 'Select none',
+      crsNoNewAccounts: 'All CRS accounts are already synced.',
+      crsWillUpdate: 'Will update {count} existing accounts.',
+      crsSelectedCount: '{count} new accounts selected',
+      crsUpdateBehaviorNote:
+        'Existing accounts only sync fields returned by CRS; missing fields keep their current values. Credentials are merged by key — keys not returned by CRS are preserved. Proxies are kept when "Sync proxies" is unchecked.',
+      crsBack: 'Back',
       editAccount: 'Edit Account',
       deleteAccount: 'Delete Account',
       searchAccounts: 'Search accounts...',

frontend/src/i18n/locales/zh.ts

@@ -1397,9 +1397,22 @@ export default {
       syncResult: '同步结果',
       syncResultSummary: '创建 {created}，更新 {updated}，跳过 {skipped}，失败 {failed}',
       syncErrors: '错误/跳过详情',
-      syncCompleted: '同步完成：创建 {created}，更新 {updated}',
-      syncCompletedWithErrors: '同步完成但有错误：失败 {failed}（创建 {created}，更新 {updated}）',
+      syncCompleted: '同步完成：创建 {created}，更新 {updated}，跳过 {skipped}',
+      syncCompletedWithErrors: '同步完成但有错误：失败 {failed}（创建 {created}，更新 {updated}，跳过 {skipped}）',
       syncFailed: '同步失败',
+      crsPreview: '预览',
+      crsPreviewing: '预览中...',
+      crsPreviewFailed: '预览失败',
+      crsExistingAccounts: '将自动更新的已有账号',
+      crsNewAccounts: '新账号（可选择）',
+      crsSelectAll: '全选',
+      crsSelectNone: '全不选',
+      crsNoNewAccounts: '所有 CRS 账号均已同步。',
+      crsWillUpdate: '将更新 {count} 个已有账号。',
+      crsSelectedCount: '已选择 {count} 个新账号',
+      crsUpdateBehaviorNote:
+        '已有账号仅同步 CRS 返回的字段，缺失字段保持原值；凭据按键合并，不会清空未下发的键；未勾选"同步代理"时保留原有代理。',
+      crsBack: '返回',
       editAccount: '编辑账号',
       deleteAccount: '删除账号',
       deleteConfirmMessage: "确定要删除账号 '{name}' 吗？",