It seems the logic here results in a valid zstd frame with no compression done whatsoever, which isn't what anyone wants imo.

I don't even know what this corresponds to in the CLI utility, as zstd -0 on the result of above does perform significant compression. The man page for my version describes the "normal range" as between 1 and 19.

I think ideally the documentation would be clarified that Fastest means "the fastest mode performing useful compression", and the value tuned. Alternatively this gotcha could be documented