server {
    listen 80;
    server_name localhost;

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

    # Allow uploads up to 60 MB (backend limit is 50 MB by default,
    # configured via MAX_UPLOAD_SIZE_MB; headroom for multipart overhead).
    # nginx default is 1 MB, which causes 413 errors on large uploads.
    client_max_body_size 60M;

    # ── API proxy ─────────────────────────────────────────────────
    # Container runtime (Docker/Podman) resolves backend:8000 via
    # its built-in DNS (127.0.0.11).  Without a resolver, nginx caches
    # the resolved IP at startup and returns 502 when the backend
    # container is recreated.  The resolver + valid=5s forces periodic
    # re-resolution so the frontend survives backend restarts.
    resolver 127.0.0.11 valid=5s;
    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_connect_timeout 30s;
        proxy_read_timeout 400s;
        proxy_send_timeout 400s;
    }

    # ── Static files ──────────────────────────────────────────────
    location / {
        try_files $uri $uri/ /index.html;
        expires 1y;
        add_header Cache-Control "public, immutable";
    }
}