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

    # SPA fallback — all routes serve index.html
    location / {
        try_files $uri $uri/ /index.html;
    }

    # No cache for index.html and service worker
    location = /index.html {
        add_header Cache-Control "no-cache, no-store, must-revalidate";
    }
    location = /sw.js {
        add_header Cache-Control "no-cache, no-store, must-revalidate";
    }

    # Cache static assets (30 days, immutable)
    location /assets/ {
        expires 30d;
        add_header Cache-Control "public, immutable";
    }
}