Fix AI result panel visibility and nginx streaming headers.

ResultAI had h-0 collapsing output; add X-Accel-Buffering no, clearer fetch errors, and NGINX.md for gate proxy setup.

Co-authored-by: Cursor <cursoragent@cursor.com>

lib/ai/client-stream.ts

@@ -1,18 +1,30 @@
 import type { AiRequestBody } from "@/lib/ai/types";
 
+function parseApiError(text: string, status: number): string {
+  const trimmed = text.trim();
+  if (
+    trimmed.startsWith("<!DOCTYPE") ||
+    trimmed.startsWith("<html") ||
+    trimmed.includes("<title>404")
+  ) {
+    return `AI 接口未到达后端 (${status})。请确认 Nginx 反代到 3130 且包含 /api/ 路径。`;
+  }
+  return trimmed.slice(0, 800) || `AI 请求失败 (${status})`;
+}
+
 export async function streamAiCompletion(
   body: AiRequestBody,
   onUpdate: (text: string) => void,
 ): Promise<void> {
   const res = await fetch("/api/ai", {
     method: "POST",
+    cache: "no-store",
     headers: { "Content-Type": "application/json" },
     body: JSON.stringify(body),
   });
 
   if (!res.ok) {
-    const message = (await res.text()).trim();
-    throw new Error(message || `AI 请求失败 (${res.status})`);
+    throw new Error(parseApiError(await res.text(), res.status));
   }
 
   if (!res.body) {
@@ -31,4 +43,11 @@ export async function streamAiCompletion(
     text += decoder.decode(value, { stream: true });
     onUpdate(text);
   }
+
+  text += decoder.decode();
+  onUpdate(text);
+
+  if (!text.trim()) {
+    throw new Error("AI 返回内容为空，请检查模型配置或稍后重试");
+  }
 }