Worked on the elixir-lang/elixir repository to enhance deprecation guidance for the --app flag in the mix cmd tool, focusing on documentation improvement using Elixir. The update clarified instructions for users managing multi-app workflows, aligning deprecation messaging with established policies and addressing confusion highlighted in issue #14239. By updating warning text and providing actionable guidance, the changes reduced upgrade friction without altering core functionality or introducing risk to existing workflows. The work emphasized clear communication and low-risk implementation, leveraging skills in documentation and Elixir language expertise to support smoother transitions for developers maintaining or upgrading Elixir-based applications.