Class DefaultHttpTransport

The Node.js transport, and the SDK default there. It is the full conformance profile: a private keep-alive connection pool that nothing else in the process shares, a connect timeout separate from the read deadline, at most maxRedirects redirects with caller headers dropped on a cross-origin hop, a streaming body cap that fails one chunk past maxResponseBytes, and a bounded drain on close.

It uses whatever proxy configuration Node applied to its own global agents at startup (--use-env-proxy or NODE_USE_ENV_PROXY, Node 24.5 / 22.19 and later, reading HTTP_PROXY, HTTPS_PROXY and NO_PROXY), so it agrees with http.globalAgent in every case. A proxy installed on the global fetch through undici.setGlobalDispatcher() is not seen here; an application using one injects FetchHttpTransport instead.

Bodies are decoded transparently when a server compresses them; the body cap applies to the decoded bytes, which is what the SDK allocates.