# GitHub Copilot Stacked Sessions: My 10-Year Refactor Story > Source: > Published: 2026-07-31 19:07:10+00:00 # GitHub Copilot Stacked Sessions: My 10-Year Refactor Story [GitHub Copilot](/en/tags/github%20copilot/)app is quietly the most useful thing for anyone staring down an old codebase. Stacked sessions are exactly what they sound like: a sequence of tasks in the same repository where each session picks up where the previous one left off. I put that pattern through a brutal real-world test — modernizing a personal dashboard app I haven't seriously touched since 2014. The state of things: React 15 (2016 vintage), Less for CSS preprocessing, react-bootstrap from the same era. The app still works, but untangling it without AI would've been a multi-week nightmare. I'd actually tried and given up before. It's not a huge codebase, but it's just big enough to hurt. So I loaded the repo into the Copilot app and started in Plan mode, throwing the whole problem at it in one shot: ``` text I want to modernize the frontend for this project. I first wrote a lot of this code more than 10 years ago and it should be cleaned up a lot. I'm thinking we start either using Tailwind or just vanilla CSS (please vet everything to help me decide), we remove all Less (etc), and clean everything up accessibility-wise and responsiveness-wise. Right now I really want to just focus on styles, and then slowly [Next Gemini Robotics 2: Whole-Body Humanoid Control →](/en/threads/4443/)