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

@@ -0,0 +1,112 @@
+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) {