Replace RSC streaming with /api/ai Route Handler for Docker reliability.

Server Actions + createStreamableValue kept failing in production; fetch-based text stream avoids RSC serialization issues and shows readable error messages.

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

app/api/ai/route.ts

@@ -0,0 +1,44 @@
+import { streamText } from "ai";
+import { createOpenAI } from "@ai-sdk/openai";
+import { buildAiMessages } from "@/lib/ai/build-messages";
+import {
+  getOpenAiApiKey,
+  getOpenAiBaseUrl,
+  getOpenAiModel,
+} from "@/lib/ai/config";
+import type { AiRequestBody } from "@/lib/ai/types";
+
+export const runtime = "nodejs";
+
+export async function POST(req: Request) {
+  try {
+    const body = (await req.json()) as AiRequestBody;
+    if (!body?.mode || !body.payload) {
+      return new Response("请求格式错误", { status: 400 });
+    }
+
+    const { system, user } = await buildAiMessages(body);
+    const openai = createOpenAI({
+      apiKey: getOpenAiApiKey(),
+      baseURL: getOpenAiBaseUrl(),
+    });
+
+    const result = streamText({
+      temperature: 0.5,
+      model: openai(getOpenAiModel()),
+      messages: [
+        { role: "system", content: system },
+        { role: "user", content: user },
+      ],
+      maxRetries: 0,
+    });
+
+    return result.toTextStreamResponse();
+  } 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" },
+    });
+  }
+}