diff --git a/desktop/src/store/connectionStore.ts b/desktop/src/store/connectionStore.ts
index cd6d438..6b4f929 100644
--- a/desktop/src/store/connectionStore.ts
+++ b/desktop/src/store/connectionStore.ts
@@ -501,7 +501,14 @@ export const useConnectionStore = create<ConnectionStore>((set, get) => {
               if (!fallbackId) {
                 throw new Error('可用模型数据格式异常，请刷新页面重试');
               }
-              const modelToUse = preferredModel || fallbackId;
+              // 验证 preferredModel 是否在 SaaS 可用模型列表中
+              // 避免使用上一次非 SaaS 会话残留的模型 ID
+              const validModelIds = new Set(
+                relayModels.flatMap(m => [m.id, ...(m.alias ? [m.alias] : [])])
+              );
+              const modelToUse = (preferredModel && validModelIds.has(preferredModel))
+                ? preferredModel
+                : fallbackId;
 
               kernelClient.setConfig({
                 provider: 'custom',
@@ -540,12 +547,16 @@ export const useConnectionStore = create<ConnectionStore>((set, get) => {
               if (!fallbackModelId) {
                 throw new Error('可用模型数据格式异常，请刷新页面重试');
               }
+              // 浏览器路径也验证模型是否在 SaaS 列表中
+              const validBrowserModelIds = new Set(
+                relayModels.flatMap(m => [m.id, ...(m.alias ? [m.alias] : [])])
+              );
               const relayClient = createSaaSRelayGatewayClient(session.saasUrl, () => {
                 // 每次调用时读取 conversationStore 的 currentModel，fallback 到第一个可用模型
                 try {
                   const { useConversationStore } = require('./chat/conversationStore');
                   const current = useConversationStore.getState().currentModel;
-                  return current || fallbackModelId;
+                  return (current && validBrowserModelIds.has(current)) ? current : fallbackModelId;
                 } catch {
                   return fallbackModelId;
                 }