Emmimal/context-compiler ? reverse-engineered prompt

Build me a small pure Python tool that helps a coding agent send only the right parts of a codebase to the model.

I want it to take a repo path and a target file, then figure out what that file depends on, keep the target file in full, turn related files into short interface only versions, and leave everything else out. It should also show me a simple summary of what was included, what was excluded, and roughly how much context I saved compared with dumping the whole repo.

Please include a tiny demo script I can run right away, a command line way to try it on a real project, and a few tests so I know the main behavior works. Keep it standard library only if possible, and make the code easy to read since I may want to tweak how far dependency tracing goes. If you need to check current Python docs or best practices, look them up online.