feat: enable API proxy

web/src/app/api/chat/stream/route.ts

@@ -0,0 +1,73 @@
+import { NextResponse, type NextRequest } from "next/server";
+
+import { env } from "~/env";
+
+export async function POST(request: NextRequest) {
+  const requestBody = await request.json();
+
+  const stream = new ReadableStream({
+    async start(controller) {
+      try {
+        const response = await fetch(
+          (env.NEXT_PUBLIC_API_URL
+            ? env.NEXT_PUBLIC_API_URL
+            : "http://localhost:8000/api") + "/chat/stream",
+          {
+            method: "POST",
+            headers: {
+              "Content-Type": "application/json",
+            },
+            body: JSON.stringify(requestBody),
+          },
+        );
+        if (!response.ok) {
+          const errorBody = await response.text();
+          console.error("API error message:", errorBody);
+          controller.enqueue(
+            createErrorEvent(`API responded with status ${response.status}`),
+          );
+          controller.close();
+          return;
+        }
+        const reader = response.body
+          ?.pipeThrough(new TextDecoderStream())
+          .getReader();
+        if (!reader) {
+          controller.enqueue(
+            createErrorEvent("No data received from /api/chat/stream"),
+          );
+          controller.close();
+          return;
+        }
+
+        while (true) {
+          const { done, value } = await reader.read();
+          if (done) {
+            break;
+          }
+          controller.enqueue(value);
+        }
+
+        controller.close();
+        reader.releaseLock();
+      } catch (error) {
+        console.error("Stream error:", error);
+        controller.enqueue(createErrorEvent("Stream interrupted"));
+        controller.close();
+      }
+    },
+  });
+
+  return new NextResponse(stream, {
+    headers: {
+      "Cache-Control": "no-cache, no-transform",
+      Connection: "keep-alive",
+      "Content-Type": "text/event-stream",
+    },
+    status: 200,
+  });
+}
+
+function createErrorEvent(message: string) {
+  return `event: error\ndata: ${message}\n\n`;
+}

web/src/core/api/chat.ts

@@ -22,7 +22,7 @@ export function chatStream(
     return chatStreamMock(userMessage, params, options);
   }
   return fetchStream<ChatEvent>(
-    (env.NEXT_PUBLIC_API_URL ?? "http://localhost:8000/api") + "/chat/stream",
+    (env.NEXT_PUBLIC_API_URL ?? "/api") + "/chat/stream",
     {
       body: JSON.stringify({
         messages: [{ role: "user", content: userMessage }],

web/src/env.js

@@ -19,7 +19,7 @@ export const env = createEnv({
    * `NEXT_PUBLIC_`.
    */
   client: {
-    NEXT_PUBLIC_API_URL: z.string(),
+    NEXT_PUBLIC_API_URL: z.string().optional(),
   },
 
   /**