Modernizing a Decade-Old Project with GitHub Copilot: A Developer's Journey
How AI-powered tools transformed my approach to legacy code maintenance
1The challenge of a 10-year-old codebase
The author's personal React project, started in 2014, relied on outdated technologies like React 15 and ancient versions of react-bootstrap. This home automation and task management dashboard became increasingly difficult to update due to deprecated dependencies. Using Less for CSS preprocessing and libraries from 2016, the project had drifted far from modern development standards, creating a significant technical debt.
2First modernization attempt with GitHub Copilot
Using GitHub Copilot's Plan mode, the author outlined a modernization strategy involving migration to Tailwind or vanilla CSS, removal of Less, and accessibility improvements. After discussions with Claude Opus 4.8 and GPT-5.5, decisions were made but the initial attempt failed. The oversight was forgetting about an existing 'dev' branch containing partial updates from a previous abandoned modernization effort.
3Branch management complications
Discovering that the current deployment used an old 'dev' branch rather than 'main' introduced new challenges. Features developed on the dev branch needed to be incorporated into the new modernization effort. In pre-AI days, such branch management issues could require hours of manual resolution. GitHub Copilot's ability to create new sessions allowed seamless transfer of style decisions to the correct branch.
4Legacy react-bootstrap issues
Testing revealed console warnings about deprecated React methods like findDOMNode and componentWillReceiveProps within react-bootstrap. The author reopened Plan mode to evaluate whether to upgrade the library or replace it entirely. After analysis, the AI recommended complete replacement with modern alternatives, acknowledging the fundamental architectural changes in React since 2016.
5Stacked sessions for task separation
The react-bootstrap replacement threatened significant scope creep. Instead of one massive pull request, the author used GitHub Copilot's stacked sessions feature to separate concerns. First, current changes were committed via pull request from dev. Then, a new session was stacked specifically for react-bootstrap replacement, maintaining context while keeping changes manageable and testable.
6Advantages of AI-assisted modernization
What could have taken weeks manually was significantly accelerated with GitHub Copilot. The AI could analyze the legacy codebase and provide intelligent suggestions for dependency resolution. The stacked sessions feature proved particularly valuable, allowing management of related but independent changes. This approach transformed a potentially frustrating process into a structured, manageable workflow.
7Managing the risk of scope creep
While AI tools make large-scale changes easier, they also increase the temptation for scope creep. The author warns against 10,000-line pull requests becoming a new form of procrastination. GitHub Copilot's stacked sessions provide an elegant solution, enabling logical separation of concerns while maintaining project context. This disciplined approach actually improves testing and code review processes.
8AI's evolving role in software maintenance
This experience highlights how AI tools are becoming valuable not just for writing new code but for maintaining and modernizing legacy systems. For neglected projects, tools like GitHub Copilot can dramatically reduce the time and effort required for updates. The AI's ability to understand context across sessions suggests a future where software lifespan could significantly increase through intelligent maintenance assistance.