facebook/zstd ? reverse-engineered prompt

Build me a fast, lossless compression tool called zstd, plus a reusable C library behind it. I want a simple command line app that can compress and decompress files, with great speed for everyday use and adjustable compression levels so people can trade size for speed. It should handle normal zstd files, and also be able to read and write common formats like gz, xz, and lz4 if that is already supported here.

Please also include the small file dictionary workflow so someone can train a dictionary from sample files, then use that dictionary for compression and decompression later. Make sure the format stays compatible with the documented standard and feels production ready.

Use the project’s main build path with make, and make sure there is an easy way to build, run the basic checks, and install it. I’d like a clean CLI experience with sensible help text and examples. If anything is unclear, check the current docs online and wire it up the way this project expects.