The way URLs are defined makes one believe the exact name of service is accepted. https://github.com/twitchtv/twirp/blob/03ac4c/docs/spec_v5.md#urls

In practice however both service and method names are changed. https://github.com/twitchtv/twirp/blob/03ac4c/protoc-gen-twirp/generator.go#L956

Should I add this to the spec for clarity and such that others do not get blind-sided by it while implementing?

@khevse discovered it in twirpy
I believe at least the rust, swagger, TypeScript, Dart and php implementations suffer from this.

Aside: The method itself is marked internal API. It might be easier for implementations if it were public https://github.com/twitchtv/twirp/blob/03ac4c/internal/gen/stringutils/stringutils.go#L71