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

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

    # Runtime config — always revalidate so env changes apply after restart
    location = /config.js {
        add_header Cache-Control "no-cache, no-store, must-revalidate";
        try_files $uri =404;
    }

    # Hashed assets — long cache
    location /assets/ {
        add_header Cache-Control "public, max-age=31536000, immutable";
        try_files $uri =404;
    }

    # Service worker / workbox — always revalidate
    location ~* ^/(sw\.js|workbox-.*\.js)$ {
        add_header Cache-Control "no-cache";
        try_files $uri =404;
    }

    gzip on;
    gzip_types text/css application/javascript application/json image/svg+xml;
}