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>

app/api/ai/route.ts

@@ -10,6 +10,11 @@ import type { AiRequestBody } from "@/lib/ai/types";
 
 export const runtime = "nodejs";
 
+const STREAM_HEADERS = {
+  "Cache-Control": "no-cache, no-transform",
+  "X-Accel-Buffering": "no",
+};
+
 export async function POST(req: Request) {
   try {
     const body = (await req.json()) as AiRequestBody;
@@ -33,12 +38,19 @@ export async function POST(req: Request) {
       maxRetries: 0,
     });
 
-    return result.toTextStreamResponse();
+    const response = result.toTextStreamResponse();
+    for (const [key, value] of Object.entries(STREAM_HEADERS)) {
+      response.headers.set(key, value);
+    }
+    return response;
   } catch (err) {
     const message = err instanceof Error ? err.message : String(err);
     return new Response(message, {
       status: 500,
-      headers: { "Content-Type": "text/plain; charset=utf-8" },
+      headers: {
+        "Content-Type": "text/plain; charset=utf-8",
+        ...STREAM_HEADERS,
+      },
     });
   }
 }