server {
    listen 80;
    root /usr/share/nginx/html;
    index index.html;

    # Static build assets. Must exist — if missing, return 404 instead of
    # falling through to index.html (which would confuse the browser with a
    # "text/html MIME for JS module" error).
    location /assets/ {
        try_files $uri =404;
        expires 1y;
        access_log off;
        add_header Cache-Control "public, immutable";
    }

    # SPA routing: serve index.html for any client-side route.
    location / {
        try_files $uri $uri/ /index.html;
    }
}