GitHub Copilot App Introduces Stacked Sessions and Stacked Pull Requests for Chained Coding Workflows
On July 30, 2026, GitHub announced Stacked Sessions and Stacked Pull Requests in the Copilot App. Rather than simple multi-session support, the release introduces a chained abstraction across both layers: session-to-session and PR-to-PR, terminating on the main branch.
What the Two Concepts Mean
- Stacked Sessions: A chain of tasks opened in the same repository. Each session continues from the previous session's output. Plan mode produces a plan, and every session is an independently executable unit.
- Stacked Pull Requests: A PR chain where each PR targets the branch of the previous PR, forming an ordered chain that eventually merges into main.
- Submit the current work as a PR
- Open a new stacked session on top of that PR, scoped to the react-bootstrap replacement and inheriting the prior context
- Auto-create a stacked PR targeting the previous PR's branch
- Avoiding mega-PRs: Developers resist reviewing single PRs that span thousands of lines, yet AI coding makes such PRs especially common. Stacking forces PRs to slice along natural boundaries.
- Preserving session context: Previously each session was an island; a new round required re-explaining the goal. Stacked sessions inherit context automatically.
- Auto-syncing PR chains: Base-branch relationships do not need manual maintenance. Merging one PR automatically advances the base of the next.
- Availability: The blog post targets all Copilot tiers. Stacked PRs are a pre-existing GitHub platform feature; Stacked Sessions are new in the Copilot App.
- Supported models: Williams used Claude Opus 4.8 with GPT-5.5 rubber-duck review, confirming that stacked sessions are model-agnostic and mixable.
- Entry point: The Copilot App main interface, in Plan mode. After a plan is produced, the system creates session nodes automatically.
- Risk: Developers must explicitly request that follow-up work be made into separate PRs. Otherwise the model tends to bundle changes into a single PR. GitHub provides no default behavior; prompt engineering is required.
- GitHub blog: https://github.blog/ai-and-ml/github-copilot/stacked-sessions-and-pull-requests-in-the-github-copilot-app
- Copilot App overview: https://github.com/features/ai/github-app
- Stacked PRs documentation: https://gh.io/stacks
Previously these were separate concerns: long Copilot tasks in the IDE required manual context merging, and PR chains required manually maintaining base branches. GitHub now links them — stacked sessions automatically produce the corresponding stacked PRs.
Cassidy Williams' Real-World Refactor
GitHub developer advocate Cassidy Williams wrote a first-person account of using the feature to modernize a 2014 personal project originally built with React 15, Less, and react-bootstrap. Her earlier manual attempt was abandoned as "too messy to be worth it." This time she fed the repository into the Copilot App:
1. Step 1: In Plan mode, she prompted Claude Opus 4.8 to remove Less, consider Tailwind, and clean up accessibility and responsive design. The model produced a plan, then GPT-5.5 reviewed it as a rubber-duck pass; a few rounds finalized it.
2. Step 2: While executing, she discovered she had accidentally branched from the old dev branch instead of main. She asked Copilot to switch branches and redo the work. The earlier plan was not wasted — the system migrated her styling decisions to dev intact.
3. Step 3: Mid-refactor she found react-bootstrap itself relied on deprecated findDOMNode and componentWillReceiveProps. She asked Plan mode whether to remove react-bootstrap or upgrade it; the model recommended a full library replacement.
4. Step 4 (the key step): She did not want the react-bootstrap replacement bundled into the same large PR — she explicitly called this a scope-creep anti-pattern. With a single prompt she asked Copilot to:
Her screen ultimately showed three layered nodes: the failed first PR, the successful PR, and the react-bootstrap replacement draft PR. She wrote in her post: "THIS WAS SO COOL. Stacked sessions *and* stacked pull requests? Is this the future? YES."
Why the Design Matters
The combined feature addresses three problems at once:
In the context of 2026 H2 AI coding-tool competition, this moves Copilot from "editor plugin" toward "PR collaboration platform." While Cursor, Codex CLI, and Claude Code still operate at the single-session level, GitHub has bolted an AI-native abstraction onto PRs — a developer-familiar collaboration unit.
Implementation Details
Practical Assessment
Williams' case was a personal side project, but the two anti-patterns she names — mega-PRs and lost session context — are common pain points across every AI coding team. Stacked Sessions + Stacked PRs are not the only solution (tools such as Graphite and Spruce enable manual PR chains via git worktree), but GitHub's advantage is building this into official repository abstractions with no third-party integration required.
The author's judgment: this workflow is a meaningful paradigm shift for "AI coding + long-running task" scenarios. The next checkpoint is whether Cursor, Codex, and Claude Code follow suit. If competitors add stacking abstractions within six months, 2026 H2 AI coding-tool competition will shift from "which model can run longer tasks" to "which workflow best breaks long tasks into pieces humans can review."