OptionalbodyOptionalheadersOptionalmaxHard cap on the response body size in bytes; the request aborts if exceeded.
OptionalredirectAlways "manual" from the engine: a transport must not follow redirects but return
the 3xx as it came (fetch(url, { redirect: req.redirect })). The engine follows them
itself — on the same host only — and decides per hop where credential headers may go;
a response whose url shows the transport went to another origin is rejected.
OptionalsignalAborted when the engine's overall deadline (timeoutMs) passes. A transport should stop
the request then (fetch(url, { signal })); the engine rejects at the deadline either
way, and enforces maxResponseBytes on the body it gets back, so neither limit depends
on the transport.
OptionaltimeoutTimeout for the whole request, response body included, in milliseconds.
Fully-qualified absolute URL.
Optional request body (already serialised).