server {
    listen 80;
    server_name _;

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

    # ── Gzip compression ─────────────────────────────────────
    gzip on;
    gzip_types text/plain text/css application/json application/javascript text/xml application/xml application/xml+rss text/javascript image/svg+xml;
    gzip_min_length 256;

    # ── Security headers ─────────────────────────────────────
    add_header Content-Security-Policy "default-src 'self'; script-src 'self'; style-src 'self' 'unsafe-inline'; img-src 'self' data:; font-src 'self'; connect-src 'self'; frame-ancestors 'none';" always;
    add_header X-Frame-Options "DENY" always;
    add_header X-Content-Type-Options "nosniff" always;
    add_header Referrer-Policy "no-referrer" always;
    add_header Permissions-Policy "geolocation=(), microphone=(), camera=()" always;
    # Uncomment when HTTPS is fully configured:
    # add_header Strict-Transport-Security "max-age=63072000; includeSubDomains; preload" always;

    # ── API reverse proxy → backend container ─────────────────
    location /api/ {
        proxy_pass         http://backend:8000;
        proxy_set_header   Host              $host;
        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_read_timeout 60s;
    }

    # ── Static assets with long-term caching ──────────────────
    location /assets/ {
        expires 1y;
        add_header Cache-Control "public, immutable";
        try_files $uri =404;
    }

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