nginx.conf

server {
    listen 80;
    server_name _;

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

    # Security headers required by Office Add-in hosting
    add_header X-Content-Type-Options "nosniff" always;
    add_header X-Frame-Options "SAMEORIGIN" always;
    add_header Referrer-Policy "strict-origin-when-cross-origin" always;

    location / {
        try_files $uri $uri/ /taskpane.html;
    }

    # Cache static assets aggressively
    location ~* \.(js|css|png|jpg|ico|svg|woff2?)$ {
        expires 1y;
        add_header Cache-Control "public, immutable";
    }

    # No caching for HTML and manifests (must update immediately)
    location ~* \.(html|xml)$ {
        expires -1;
        add_header Cache-Control "no-store, no-cache, must-revalidate";
    }
}