yaroslav/audition

Audition is a command line tool for Ruby developers that checks whether a piece of Ruby code, whether that is a single script, an installed gem, a web app, or a full Rails application, can safely run using Ractors, a feature in newer Ruby versions that allows real parallel execution across multiple CPU cores. Code that was not written with this in mind often breaks in subtle ways when run this way, and this tool finds those problems before they cause trouble in production. What sets it apart from a typical code linter is that it does not just look for suspicious patterns in your source code. It also builds a full picture of how your program's classes and files relate to each other using a separate Ruby analysis tool, and it actually runs your code inside a real Ractor in an isolated process to catch real errors as they happen, rather than only guessing from static text. Every problem it finds comes with an explanation of which underlying rule was broken and a suggested fix, and it can automatically apply many of these fixes for you, split into safer changes and more aggressive ones that could subtly change behavior, both of which can be previewed before being applied. It is aware of dependencies too, so if a problem originates in a gem you depend on rather than your own code, it tells you that clearly instead of blaming your code. It also supports scanning an entire bundle of installed gems at once and reports which ones are and are not ready. It requires Ruby 4.0 or newer, since it depends on newer Ractor features. Notably, the README states plainly that the entire tool was written by an AI system, Claude Fable 5, and while it has a test suite and has been checked against real gems, the authors caution that no human has reviewed every line, so results and automatic fixes should be checked before being trusted fully.