Stacking Prs Agent Skill

Stacked PRs with gh stack

GitHub's native stacked PRs are enabled on this repo.

A stack is an ordered chain of PRs where each one targets the branch of the PR below it; the bottom PR targets master.

GitHub tracks the chain as a first-class object: the PR UI shows a stack map, branch protections (code owner approval, required checks) apply to every layer including mid-stack ones, and CI that runs on master PRs runs on every layer.

Setup (this skill is written against gh-stack v0.1.0):

gh extension install github/gh-stack   # or: gh extension upgrade stack

Upstream docs: about stacked PRs, CLI commands.

Create a stack

gh stack init my-feature-db        # bottom branch, based on master
# ...commit...
gh stack add my-feature-api        # next layer, based on the previous branch
# ...commit...
gh stack add -Am "add UI" my-feature-ui   # stage all + commit in one step

• Adopt existing local branches (bottom to top): gh stack init branch1 branch2 branch3.
• Link PRs that already exist on GitHub, without local tracking: gh stack link <pr> <pr> <pr>, bottom to top (branch names and PR URLs work too). Pass a stack number first to append to an existing stack: gh stack link <stack> <pr>.
• Slice by reviewable unit: migration / backend / frontend, or mechanical-rename / behavior-change. Each PR must make sense to review and merge alone.
• Keep stacks shallow (2–4 layers). Every layer multiplies CI cost and rebase churn, and deep-stack pushes can trip GitHub's dispatch cap (see AGENTS.md, "Stacked PRs").

Publish

gh stack submit --auto

Pushes all branches, creates each PR with the correct base, and links the stack on GitHub.

--auto creates new PRs as drafts, the right default here, since drafts run the narrowed CI matrix.

Mark layers ready individually with gh pr ready <n>, or pass --open to mark everything ready.

Running gh stack submit with no flags opens an interactive editor for titles and descriptions instead.

New PRs default to ready-for-review in that editor, so flip its "CREATE AS" toggle if you want drafts.

Each layer is a normal PR: it needs a conventional-commit title and a description filled from .github/pull_request_template.md.

Iterate and keep in sync

gh stack sync            # fetch, cascade-rebase onto master and each parent, force-with-lease push, sync PR state
gh stack sync --prune    # also delete local branches for merged PRs

• To fix a mid-stack layer: check out that branch (gh stack down / gh stack switch), commit, then gh stack sync (or gh stack rebase --upstack to rebase only the layers above you, --no-trunk to skip pulling master).
• On rebase conflict, sync restores all branches untouched; run gh stack rebase, resolve, then gh stack rebase --continue (or --abort).
• gh stack view --short shows status (--json for scripting); a ⚠ means that layer needs a rebase, which blocks merging. gh stack checkout <stack-number|PR|URL> pulls down and tracks a stack you don't have locally, including a teammate's.
• gh stack modify interactively reorders, folds, drops, or renames layers. gh stack unstack removes the stack on GitHub (--local to only drop local tracking).
• Batch work before syncing. Each sync force-pushes and re-runs a full CI matrix for every rebased layer, so sync when you need the rebase, not to track master.
• The ci:preflight pre-push hook runs on these pushes like any other; never bypass it.

Merging

A stack lands bottom-first, one layer at a time.

Merge the layer based on master via /merging-prs, exactly as you would an unstacked PR; being in a stack changes nothing about how it reaches master.

GitHub then retargets the next layer onto master and updates the stack:

gh stack sync --prune   # replay the remaining layers onto the squashed commit, drop the merged branch

Repeat for the new bottom layer.

Do not use gh stack merge.

It merges the whole chain straight through GitHub's API, so the bottom layer reaches master outside the path AGENTS.md requires ("Merging PRs").

Merging any layer also merges every unmerged layer below it, so a mid-stack merge is only safe once those layers are reviewed and green.

Every layer is gated on its own approving review, code owner review, required checks, and signed commits.

Rule bypass and auto-merge are both unsupported for stacks, so --auto won't help you here.

Never gh stack sync, rebase, or push while a layer sits in the merge queue; the force-push kicks it out.

gh stack push knows to skip branches queued in _GitHub's_ merge queue, but it can't see Trunk's.

Scripting

• List stacks: gh api repos/{owner}/{repo}/stacks; one stack: .../stacks/<stack-number>. Stack numbers come from the same sequence as PR numbers, so they never collide.
• Local stack state: gh stack view --json.

Limits

All branches must live in the same repository (no cross-fork stacks), and the chain must be strictly linear: no branching structures, and every layer needs a rebase before it can merge.

GitHub Desktop doesn't support stacks at all.

These are preview-era constraints, so check the upstream docs before concluding something is impossible.