Stacked sessions and pull requests in the GitHub Copilot app (opens in new tab)
GitHub Copilot’s stacked sessions let developers split large, dependent changes into smaller pull requests while preserving their order. Cassidy Williams demonstrates this by modernizing a decade-old React application, recovering from an incorrect branch choice, and then starting a separate `react-bootstrap` replacement on top of the styling work. The approach made a difficult modernization more manageable and reduced the temptation to create an unwieldy “everything” pull request. ## Modernizing a Legacy Application - Williams’ personal dashboard had accumulated outdated dependencies and patterns: - React 15 - Less - An old version of `react-bootstrap` - Updating the application manually had previously seemed too time-consuming. - She used the GitHub Copilot app to plan a frontend modernization focused on: - Replacing Less with Tailwind or vanilla CSS - Improving accessibility and responsiveness - Modernizing dependencies - Cleaning up links, inputs, labels, wrapping, and container widths - Claude Opus 4.8 helped formulate the plan, while GPT-5.5 provided a review. - The initial attempt failed because the work began from the wrong branch. ## Recovering from the Wrong Branch - Williams discovered that an old `dev` branch already contained partial modernization work and was the version she actively used. - The new session had incorrectly branched from `main`, creating compatibility problems. - Rather than discard the work, she asked Copilot to: - Close the incorrect pull request - Start a fresh session from `dev` - Port the styling and accessibility changes onto that branch - Copilot handled the branch and pull request transition, preserving useful decisions from the failed attempt. ## Investigating Legacy Warnings - Testing exposed warnings involving: - `findDOMNode` - `componentWillReceiveProps` - The outdated code was largely coming from `react-bootstrap`, not Williams’ own application code. - She used Plan mode to compare upgrading or migrating existing components with removing the library. - Copilot recommended replacing `react-bootstrap` entirely. ## Stacking Dependent Sessions - Replacing `react-bootstrap` represented substantial scope beyond the current styling work. - Williams chose to submit the existing work first, then create a second session branched from it. - The new session would: - Build on the completed styling changes - Replace `react-bootstrap` - Produce a separate pull request - Eventually merge into `dev` after the first pull request - This structure keeps each change easier to review and test while maintaining the dependency between them. The practical recommendation is to use stacked sessions for large, related modernization efforts: isolate coherent tasks into separate pull requests, branch later work from earlier changes, and avoid allowing AI-assisted development to turn every improvement into one oversized change.