fix(frontend): resolve API base URL at request time for production

Use same-origin /api in the browser so builds are not stuck with baked-in
localhost. Server-side fetches use INTERNAL_API_URL, NEXT_PUBLIC_API_URL, or
loopback. Centralize logic in lib/api-base.ts.

Made-with: Cursor

frontend/app/.well-known/nostr.json/route.ts

@@ -1,10 +1,9 @@
 import { NextRequest, NextResponse } from 'next/server';
-
-const API_URL = process.env.NEXT_PUBLIC_API_URL || 'http://localhost:4000/api';
+import { apiUrl } from '@/lib/api-base';
 
 export async function GET(req: NextRequest) {
   const name = req.nextUrl.searchParams.get('name');
-  const upstream = new URL(`${API_URL}/nip05`);
+  const upstream = new URL(apiUrl('/nip05'));
   if (name) upstream.searchParams.set('name', name);
 
   const res = await fetch(upstream.toString(), { cache: 'no-store' });

frontend/app/blog/[slug]/page.tsx

@@ -1,12 +1,11 @@
 import type { Metadata } from "next";
 import BlogPostClient from "./BlogPostClient";
 import { BlogPostingJsonLd, BreadcrumbJsonLd } from "@/components/public/JsonLd";
-
-const apiUrl = process.env.NEXT_PUBLIC_API_URL || "http://localhost:4000/api";
+import { apiUrl } from "@/lib/api-base";
 
 async function fetchPost(slug: string) {
   try {
-    const res = await fetch(`${apiUrl}/posts/${slug}`, {
+    const res = await fetch(apiUrl(`/posts/${slug}`), {
       next: { revalidate: 300 },
     });
     if (!res.ok) return null;

frontend/app/calendar/route.ts

@@ -1,11 +1,10 @@
 import { NextResponse } from 'next/server';
-
-const API_URL = process.env.NEXT_PUBLIC_API_URL || 'http://localhost:4000/api';
+import { apiUrl } from '@/lib/api-base';
 
 export async function GET() {
   let upstream: Response;
   try {
-    upstream = await fetch(`${API_URL}/calendar/ics`, {
+    upstream = await fetch(apiUrl('/calendar/ics'), {
       headers: { Accept: 'text/calendar' },
       cache: 'no-store',
     });

frontend/app/events/[id]/page.tsx

@@ -1,12 +1,11 @@
 import type { Metadata } from "next";
 import EventDetailClient from "./EventDetailClient";
 import { EventJsonLd, BreadcrumbJsonLd } from "@/components/public/JsonLd";
-
-const apiUrl = process.env.NEXT_PUBLIC_API_URL || "http://localhost:4000/api";
+import { apiUrl } from "@/lib/api-base";
 
 async function fetchEvent(id: string) {
   try {
-    const res = await fetch(`${apiUrl}/meetups/${id}`, {
+    const res = await fetch(apiUrl(`/meetups/${id}`), {
       next: { revalidate: 300 },
     });
     if (!res.ok) return null;

frontend/app/sitemap.ts

@@ -1,12 +1,12 @@
 import type { MetadataRoute } from "next";
+import { apiUrl } from "@/lib/api-base";
 
 const siteUrl =
   process.env.NEXT_PUBLIC_SITE_URL || "https://belgianbitcoinembassy.org";
-const apiUrl = process.env.NEXT_PUBLIC_API_URL || "http://localhost:4000/api";
 
 async function fetchJson<T>(path: string): Promise<T | null> {
   try {
-    const res = await fetch(`${apiUrl}${path}`, { next: { revalidate: 3600 } });
+    const res = await fetch(apiUrl(path), { next: { revalidate: 3600 } });
     if (!res.ok) return null;
     return res.json();
   } catch {

frontend/lib/api-base.ts

@@ -0,0 +1,12 @@
+/** Browser: `/api/...` (same origin). Server: INTERNAL_API_URL → NEXT_PUBLIC_API_URL → loopback. */
+export function apiUrl(path: string): string {
+  const p = path.startsWith("/") ? path : `/${path}`;
+  if (typeof window !== "undefined") {
+    return `/api${p}`;
+  }
+  const base =
+    process.env.INTERNAL_API_URL ||
+    process.env.NEXT_PUBLIC_API_URL ||
+    "http://127.0.0.1:4000/api";
+  return `${base}${p}`;
+}

frontend/lib/api.ts

@@ -1,4 +1,4 @@
-const API_URL = process.env.NEXT_PUBLIC_API_URL || "http://localhost:4000/api";
+import { apiUrl } from "./api-base";
 
 async function request<T>(path: string, options?: RequestInit): Promise<T> {
   const token = typeof window !== "undefined" ? localStorage.getItem("bbe_token") : null;
@@ -8,7 +8,7 @@ async function request<T>(path: string, options?: RequestInit): Promise<T> {
     ...options?.headers,
   };
 
-  const res = await fetch(`${API_URL}${path}`, { ...options, headers });
+  const res = await fetch(apiUrl(path), { ...options, headers });
   if (!res.ok) {
     const error = await res.json().catch(() => ({ message: "Request failed" }));
     throw new Error(error.message || `HTTP ${res.status}`);
@@ -128,7 +128,7 @@ export const api = {
     const token = typeof window !== "undefined" ? localStorage.getItem("bbe_token") : null;
     const formData = new FormData();
     formData.append("file", file);
-    const res = await fetch(`${API_URL}/media/upload`, {
+    const res = await fetch(apiUrl("/media/upload"), {
       method: "POST",
       headers: token ? { Authorization: `Bearer ${token}` } : {},
       body: formData,