server {
    listen 80;
    root /usr/share/nginx/html;

    # Same-origin API: the SPA calls /api/..., nginx forwards to the backend
    # container. Mirrors the Vite dev proxy — the frontend build is identical
    # in both environments.
    location /api/ {
        # Match the backend's 5MB CSV cap so oversized uploads are rejected at
        # the edge, before they ever reach uvicorn.
        client_max_body_size 5m;
        proxy_pass http://backend:8000;
    }

    # SPA fallback: client-side routes all serve index.html.
    location / {
        try_files $uri /index.html;
    }
}