Only partially... what's available at least prevents leaking the context unexpectedly to other goroutines (due to thread re-use), however anything that spins up

Only partially... what's available at least prevents leaking the context unexpectedly to other goroutines (due to thread re-use), however anything that spins up a new goroutine from the locked goroutine will end up in a new thread in a totally different context. Even stdlib spins up new goroutines.