feat: Implement a new contract-based payment system with wallet binding, payment intents, and subscription plan management.

frontend/app/api/payments/intents/[intentId]/route.ts

@@ -0,0 +1,47 @@
+import { NextRequest, NextResponse } from "next/server";
+import {
+  applyAuthResponseCookies,
+  buildBackendRequestHeaders,
+} from "@/lib/backend-auth";
+
+const API_BASE = process.env.POLYWEATHER_API_BASE_URL;
+
+export async function GET(
+  req: NextRequest,
+  context: { params: Promise<{ intentId: string }> },
+) {
+  if (!API_BASE) {
+    return NextResponse.json(
+      { error: "POLYWEATHER_API_BASE_URL is not configured" },
+      { status: 500 },
+    );
+  }
+  const { intentId } = await context.params;
+  try {
+    const auth = await buildBackendRequestHeaders(req);
+    const res = await fetch(
+      `${API_BASE}/api/payments/intents/${encodeURIComponent(intentId)}`,
+      {
+        method: "GET",
+        headers: auth.headers,
+        cache: "no-store",
+      },
+    );
+    if (!res.ok) {
+      const raw = await res.text();
+      const response = NextResponse.json(
+        { error: `Backend returned ${res.status}`, detail: raw.slice(0, 350) },
+        { status: res.status },
+      );
+      return applyAuthResponseCookies(response, auth.response);
+    }
+    const data = await res.json();
+    const response = NextResponse.json(data);
+    return applyAuthResponseCookies(response, auth.response);
+  } catch (error) {
+    return NextResponse.json(
+      { error: "Failed to fetch payment intent", detail: String(error) },
+      { status: 500 },
+    );
+  }
+}