fix: clarify ark agent plan model discovery

web/src/app/(admin)/admin/settings/page.tsx

@@ -215,6 +215,10 @@ export default function AdminSettingsPage() {
             const channelModels = await fetchChannelModels(token, { index: editingChannelIndex ?? undefined, channel: normalizeChannel(channel) });
             const current = isModelSelectorOpen ? uniqueModels(modelSelectSelected) : uniqueModels(channelForm.getFieldValue("models") || []);
             rememberModels(channelModels);
+            if (!channelModels.length) {
+                message.warning("上游未返回模型列表，请手动输入模型名称");
+                return;
+            }
             setModelSelectExisting(current);
             setModelSelectSource(uniqueModels(channelModels));
             setModelSelectSelected(uniqueModels([...current, ...channelModels]));
@@ -707,6 +711,7 @@ export default function AdminSettingsPage() {
                                 </Button>
                             </Space.Compact>
                         </Flex>
+                        <Typography.Text type="secondary">如果上游不提供 OpenAI /models 模型列表接口，请在这里手动增加模型名称。</Typography.Text>
                         <Tabs
                             activeKey={modelSelectTab}
                             onChange={(key) => setModelSelectTab(key as ModelSelectTabKey)}
@@ -765,7 +770,7 @@ export default function AdminSettingsPage() {
                     destroyOnHidden
                 >
                     <Flex vertical gap={12}>
-                        <Typography.Text type="secondary">测试会向选中模型发送一条 hi，用于确认渠道是否有响应。</Typography.Text>
+                        <Typography.Text type="secondary">普通文本模型会发送一条 hi；Agent Plan / Seedance 视频模型只做配置格式检查，不会发起视频生成，也不代表模型权限已验证。</Typography.Text>
                         <Input.Search placeholder="搜索模型..." allowClear value={testKeyword} onChange={(event) => setTestKeyword(event.target.value)} />
                         <Table
                             rowKey="model"