diff --git a/backend/internal/handler/admin/account_handler.go b/backend/internal/handler/admin/account_handler.go
index 4f566a8be9f..5719534230b 100644
--- a/backend/internal/handler/admin/account_handler.go
+++ b/backend/internal/handler/admin/account_handler.go
@@ -2131,6 +2131,56 @@ func (h *AccountHandler) SyncUpstreamModels(c *gin.Context) {
 	response.Success(c, gin.H{"models": models})
 }
 
+// SyncUpstreamModelsPreview handles syncing live supported models using provided credentials (no account ID needed).
+// POST /api/v1/admin/accounts/models/sync-upstream-preview
+func (h *AccountHandler) SyncUpstreamModelsPreview(c *gin.Context) {
+	var req struct {
+		Platform string `json:"platform" binding:"required"`
+		Type     string `json:"type" binding:"required"`
+		BaseURL  string `json:"base_url"`
+		APIKey   string `json:"api_key" binding:"required"`
+	}
+	if err := c.ShouldBindJSON(&req); err != nil {
+		response.BadRequest(c, "Invalid request: "+err.Error())
+		return
+	}
+
+	tempAccount := &service.Account{
+		Platform: req.Platform,
+		Type:     req.Type,
+		Credentials: map[string]any{
+			"api_key":  req.APIKey,
+			"base_url": req.BaseURL,
+		},
+	}
+
+	if h.accountTestService == nil {
+		response.InternalError(c, "Account test service is not configured")
+		return
+	}
+
+	models, err := h.accountTestService.FetchUpstreamSupportedModels(c.Request.Context(), tempAccount)
+	if err != nil {
+		var syncErr *service.UpstreamModelSyncError
+		if errors.As(err, &syncErr) {
+			switch syncErr.Kind {
+			case service.UpstreamModelSyncErrorConfiguration, service.UpstreamModelSyncErrorUnsupported:
+				response.BadRequest(c, syncErr.SafeMessage())
+			default:
+				slog.Warn("sync_upstream_models_preview_failed", "platform", req.Platform, "kind", syncErr.Kind)
+				response.Error(c, http.StatusBadGateway, syncErr.SafeMessage())
+			}
+			return
+		}
+
+		slog.Warn("sync_upstream_models_preview_failed", "platform", req.Platform)
+		response.Error(c, http.StatusBadGateway, "Failed to sync upstream models from upstream")
+		return
+	}
+
+	response.Success(c, gin.H{"models": models})
+}
+
 // SetPrivacy handles setting privacy for a single OpenAI/Antigravity OAuth account
 // POST /api/v1/admin/accounts/:id/set-privacy
 func (h *AccountHandler) SetPrivacy(c *gin.Context) {
diff --git a/backend/internal/server/routes/admin.go b/backend/internal/server/routes/admin.go
index 2301adda6bf..9a3253b55dd 100644
--- a/backend/internal/server/routes/admin.go
+++ b/backend/internal/server/routes/admin.go
@@ -302,6 +302,7 @@ func registerAccountRoutes(admin *gin.RouterGroup, h *handler.Handlers) {
 		accounts.GET("/:id/temp-unschedulable", h.Admin.Account.GetTempUnschedulable)
 		accounts.DELETE("/:id/temp-unschedulable", h.Admin.Account.ClearTempUnschedulable)
 		accounts.POST("/:id/schedulable", h.Admin.Account.SetSchedulable)
+		accounts.POST("/models/sync-upstream-preview", h.Admin.Account.SyncUpstreamModelsPreview)
 		accounts.GET("/:id/models", h.Admin.Account.GetAvailableModels)
 		accounts.POST("/:id/models/sync-upstream", h.Admin.Account.SyncUpstreamModels)
 		accounts.POST("/batch", h.Admin.Account.BatchCreate)
diff --git a/frontend/src/api/admin/accounts.ts b/frontend/src/api/admin/accounts.ts
index 6fd23c475d4..bb75e30251d 100644
--- a/frontend/src/api/admin/accounts.ts
+++ b/frontend/src/api/admin/accounts.ts
@@ -487,6 +487,23 @@ export async function syncUpstreamModels(id: number): Promise<SyncUpstreamModels
   return data
 }
 
+export interface SyncUpstreamPreviewParams {
+  platform: string
+  type: string
+  base_url?: string
+  api_key: string
+}
+
+/**
+ * Preview upstream models without a saved account (create-flow)
+ * @param params - Connection credentials
+ * @returns List of model IDs returned by the upstream
+ */
+export async function syncUpstreamModelsPreview(params: SyncUpstreamPreviewParams): Promise<SyncUpstreamModelsResult> {
+  const { data } = await apiClient.post<SyncUpstreamModelsResult>('/admin/accounts/models/sync-upstream-preview', params)
+  return data
+}
+
 export interface CRSPreviewAccount {
   crs_account_id: string
   kind: string
@@ -703,6 +720,7 @@ export const accountsAPI = {
   setSchedulable,
   getAvailableModels,
   syncUpstreamModels,
+  syncUpstreamModelsPreview,
   generateAuthUrl,
   exchangeCode,
   refreshOpenAIToken,
diff --git a/frontend/src/components/account/CreateAccountModal.vue b/frontend/src/components/account/CreateAccountModal.vue
index a8abfd9f419..d1a7729a58d 100644
--- a/frontend/src/components/account/CreateAccountModal.vue
+++ b/frontend/src/components/account/CreateAccountModal.vue
@@ -1124,7 +1124,7 @@
 
             <!-- Whitelist Mode -->
             <div v-if="modelRestrictionMode === 'whitelist'">
-              <ModelWhitelistSelector v-model="allowedModels" :platform="form.platform" />
+              <ModelWhitelistSelector v-model="allowedModels" :platform="form.platform" :sync-credentials="syncPreviewCredentials" />
               <p class="text-xs text-gray-500 dark:text-gray-400">
                 {{ t('admin.accounts.selectedModels', { count: allowedModels.length }) }}
                 <span v-if="allowedModels.length === 0">{{
@@ -1562,7 +1562,7 @@
 
           <!-- Whitelist Mode -->
           <div v-if="modelRestrictionMode === 'whitelist'">
-            <ModelWhitelistSelector v-model="allowedModels" platform="anthropic" />
+            <ModelWhitelistSelector v-model="allowedModels" platform="anthropic" :sync-credentials="syncPreviewCredentials" />
             <p class="text-xs text-gray-500 dark:text-gray-400">
               {{ t('admin.accounts.selectedModels', { count: allowedModels.length }) }}
               <span v-if="allowedModels.length === 0">{{ t('admin.accounts.supportsAllModels') }}</span>
@@ -1813,7 +1813,7 @@
 
           <!-- Whitelist Mode -->
           <div v-if="modelRestrictionMode === 'whitelist'">
-            <ModelWhitelistSelector v-model="allowedModels" :platform="form.platform" />
+            <ModelWhitelistSelector v-model="allowedModels" :platform="form.platform" :sync-credentials="syncPreviewCredentials" />
             <p class="text-xs text-gray-500 dark:text-gray-400">
               {{ t('admin.accounts.selectedModels', { count: allowedModels.length }) }}
               <span v-if="allowedModels.length === 0">{{
@@ -3361,6 +3361,17 @@ const accountCategory = ref<'oauth-based' | 'apikey' | 'bedrock' | 'service_acco
 const addMethod = ref<AddMethod>('oauth') // For oauth-based: 'oauth' or 'setup-token'
 const apiKeyBaseUrl = ref('https://api.anthropic.com')
 const apiKeyValue = ref('')
+
+const syncPreviewCredentials = computed(() => {
+  if (!apiKeyValue.value) return undefined
+  return {
+    platform: form.platform,
+    type: form.type,
+    base_url: apiKeyBaseUrl.value || undefined,
+    api_key: apiKeyValue.value
+  }
+})
+
 const editQuotaLimit = ref<number | null>(null)
 const editQuotaDailyLimit = ref<number | null>(null)
 const editQuotaWeeklyLimit = ref<number | null>(null)
diff --git a/frontend/src/components/account/ModelWhitelistSelector.vue b/frontend/src/components/account/ModelWhitelistSelector.vue
index 9a0d6af80f3..d4d726d06ab 100644
--- a/frontend/src/components/account/ModelWhitelistSelector.vue
+++ b/frontend/src/components/account/ModelWhitelistSelector.vue
@@ -133,6 +133,7 @@ import { ref, computed } from 'vue'
 import { useI18n } from 'vue-i18n'
 import { useAppStore } from '@/stores/app'
 import { accountsAPI } from '@/api/admin/accounts'
+import type { SyncUpstreamPreviewParams } from '@/api/admin/accounts'
 import ModelIcon from '@/components/common/ModelIcon.vue'
 import Icon from '@/components/icons/Icon.vue'
 import { allModels, getModelsByPlatform } from '@/composables/useModelWhitelist'
@@ -144,6 +145,12 @@ const props = defineProps<{
   platform?: string
   platforms?: string[]
   accountId?: number
+  syncCredentials?: {
+    platform: string
+    type: string
+    base_url?: string
+    api_key: string
+  }
 }>()
 
 const emit = defineEmits<{
@@ -176,9 +183,14 @@ const normalizedPlatforms = computed(() => {
 
 const upstreamSyncPlatforms = new Set(['anthropic', 'openai', 'gemini', 'antigravity'])
 const canSyncUpstream = computed(() => {
-  if (!props.accountId) return false
-  if (normalizedPlatforms.value.length === 0) return true
-  return normalizedPlatforms.value.some(platform => upstreamSyncPlatforms.has(platform.toLowerCase()))
+  if (props.accountId) {
+    if (normalizedPlatforms.value.length === 0) return true
+    return normalizedPlatforms.value.some(platform => upstreamSyncPlatforms.has(platform.toLowerCase()))
+  }
+  if (props.syncCredentials) {
+    return upstreamSyncPlatforms.has(props.syncCredentials.platform.toLowerCase())
+  }
+  return false
 })
 
 const availableOptions = computed(() => {
@@ -249,11 +261,20 @@ const fillRelated = () => {
 }
 
 const syncUpstreamModels = async () => {
-  if (!props.accountId || isSyncingUpstream.value) return
+  if (isSyncingUpstream.value) return
+  if (!props.accountId && !props.syncCredentials) return
 
   isSyncingUpstream.value = true
   try {
-    const result = await accountsAPI.syncUpstreamModels(props.accountId)
+    let result
+    if (props.accountId) {
+      result = await accountsAPI.syncUpstreamModels(props.accountId)
+    } else if (props.syncCredentials) {
+      result = await accountsAPI.syncUpstreamModelsPreview(props.syncCredentials as SyncUpstreamPreviewParams)
+    } else {
+      return
+    }
+
     const upstreamModels = result.models.map(model => model.trim()).filter(Boolean)
     if (upstreamModels.length === 0) {
       appStore.showInfo(t('admin.accounts.syncUpstreamModelsEmpty'))