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. The engine
follows them itself and decides per hop whether the Authorization header goes along
(same origin only). A fetch-based transport passes it on: fetch(url, { redirect }).
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 it.
OptionaltimeoutTimeout for the whole request, response body included, in milliseconds.
Fully-qualified absolute URL.
Optional request body (already serialised).