server {
    listen 80;
    server_name _;

    root /usr/share/nginx/html;
    index index.html;

    # Frontend SPA
    location / {
        try_files $uri /index.html;
    }

    # Backend API - configurable via BACKEND_BASEURL (e.g. http://backend:8000)
    location /api {
        proxy_pass $BACKEND_BASEURL;
        proxy_http_version 1.1;
        proxy_set_header Upgrade $http_upgrade;
        proxy_set_header Connection 'upgrade';
        proxy_set_header Host $host;
        proxy_cache_bypass $http_upgrade;
        proxy_set_header X-Real-IP $remote_addr;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_set_header X-Forwarded-Proto $scheme;
        proxy_connect_timeout 300s;
        proxy_send_timeout 300s;
        proxy_read_timeout 300s;
    }
}