Gh Stack

GitHub Native Stacked Pull Requests

A stack is a chain of two or more PRs in one repository: the bottom targets main, and each one above targets the branch of the PR below it. GitHub tracks the stack as a first-class object and renders a stack map on every member, so reviewers can see the layering without reading each body.

Use a stack when a change is large enough that one PR would be hard to review but the parts are genuinely dependent. For one or two independent PRs, don't — a plain branch off main is simpler.

Prerequisites

gh extension install github/gh-stack
gh stack --version

Docs: https://docs.github.com/en/pull-requests/how-tos/stacked-pull-requests

Constraints worth knowing before you start:

• Same repository only. Cross-fork stacks are not supported, so this works for maintainers pushing branches to camunda/camunda-platform-helm, not for fork-based contributions.
• Merge bottom-up. A PR cannot land before the ones below it.
• GitHub Desktop does not support stacks.

Setting a base branch does NOT create a stack

This is the trap. Creating a PR whose --base is the branch below it produces a correct base chain and no stack: the PR reports .stack == null and gets no stack map. The stack is an explicit object you create or join.

# Chained bases only — NOT yet a stack:
gh pr create --draft --base <branch-below> --head <my-branch> --title "..." --body-file body.md

# Then actually put it in the stack:
gh stack link <stack-number> <pr-number>

Verify, don't assume:

gh api /repos/camunda/camunda-platform-helm/pulls/<n> --jq '.stack'
# -> {"number":<stack>,"position":6,"size":6,...}   or  null

Starting a stack

Two entry points, depending on whether the branches already exist.

From scratch, building up as you go:

gh stack init                  # start a stack on the current branch, targeting the default branch
# ... commit work ...
gh stack add <next-branch>     # add a branch on top of the current stack
gh stack submit                # push all branches, create/update the PRs, and create the stack

gh stack submit opens an editor to set each PR's title, body, and draft state. Pass --auto (or run non-interactively) to accept auto-generated titles — avoid that here, because this repo enforces Conventional Commit PR titles (see below).

From branches that already exist:

gh stack init branch1 branch2 branch3   # adopt existing branches, bottom to top

Adopting PRs that already exist

gh stack link works without local tracking state, which makes it the right tool for a stack that was built by hand with chained bases.

# Create a stack from existing PRs, listed bottom to top:
gh stack link 6884 6889 6891 6893 6902

# Or append to an existing stack — pass the stack number first, then only what's new:
gh stack link 6894 6904

Arguments may be branch names, PR numbers, or PR URLs. Arguments already in the stack are skipped and existing PRs are never removed, so re-running is safe. A numeric first argument is treated as a stack number only when a stack with that number exists; stack and PR numbers never overlap.

Daily loop

gh stack view                  # branches + PR status; --short for one line each, --json to script it
gh stack sync                  # the one command to reach for after main moves
gh stack rebase                # cascading rebase only, no PR-state sync; --no-trunk to skip trunk
gh stack checkout <stack|pr|url|branch>
gh stack up / down / top / bottom / switch / trunk

gh stack sync fetches, reconciles the local stack against GitHub, fast-forwards trunk, cascade-rebases each branch onto its updated parent, force-pushes atomically with --force-with-lease --atomic, syncs PR state, and links the open PRs into a stack when two or more exist.

Use gh stack sync or gh stack rebase instead of rebasing each branch by hand. Rebasing a stack manually means picking the right old base for every branch, and getting it wrong silently drops commits — in this repo that has already cost a lost feature commit that had to be recovered by cherry-pick. The cascade does the bookkeeping.

Rebasing rewrites history and force-pushes, which is correct here: this repo forbids merge commits (see AGENTS.md), so git merge is never the way to take in upstream changes.

Restructuring

gh stack modify      # interactively reorder, insert, or drop layers
gh stack unstack     # remove the stack locally and on GitHub (the PRs stay open)

If a layer turns out to be independent, take it out of the stack and retarget it at main rather than leaving reviewers to guess why it is stacked.

Landing the stack

gh stack merge                 # current branch's stack
gh stack merge <stack-number>  # a stack you don't have checked out
gh stack merge <pr-number>     # everything up to and including that PR

This is GitHub's atomic stack merge: every PR up to your chosen one merges in a single all-or-nothing operation, so if any one cannot merge, none do. Interactively it offers a wizard to choose how far up to merge and which merge method; --yes or a non-interactive terminal merges the whole selection without prompting.

When a PR merges, GitHub automatically re-targets and rebases the PRs above it, so there is no need to repoint bases by hand. Merging a mid-stack PR leaves the ones above open, re-targeted at the stack's base.

Confirm before relying on it in this repo: the full ~33-deploy matrix runs in the merge queue, not on the PR (see the rfr-validation skill). How an atomic stack merge interacts with this repo's merge queue and required checks has not been verified here — check with a maintainer before using gh stack merge on a stack that must go through the queue, and fall back to merging one PR at a time if in doubt.

Repo conventions that still apply per PR

A stack does not exempt any member from the normal rules in AGENTS.md and docs/contribution-and-collaboration.md:

• Conventional Commit titles, individually. Each PR is titled for its own diff. feat:, fix:, refactor:, docs:, and revert: are reserved for PRs that change user-facing chart files; a PR in the stack that only touches .github/, scripts/, or tests must use ci:, build:, chore:, or test: or CI rejects it. It is normal for one stack to mix types.
• Draft-first, then crev. Open each PR as a draft, run crev https://github.com/camunda/camunda-platform-helm/pull/<n> against it, address findings, then gh pr ready <n>. Review the whole stack before landing any of it, because a change demanded in a lower PR forces a cascade rebase of everything above.
• Regenerate artifacts in the PR that changes them, not in a later layer, or the intermediate PR is left with a failing make go.test.
• Do not hand-maintain position markers. GitHub owns position and size; a [TAG N/M] marker in the title or a stack table copied into every body is a second source of truth that goes stale the moment the stack grows. Let the stack map speak.

Inspecting a stack from the API

Useful when scripting or when the UI is not to hand.

# Every PR carries its stack membership:
gh api /repos/camunda/camunda-platform-helm/pulls/<n> --jq '.stack'

# The stack itself is addressable, with its PRs in order:
gh api /repos/camunda/camunda-platform-helm/stacks/<stack-number> \
  --jq '.pull_requests[] | "#\(.number) \(.head.ref) \(.title)"'

# One-line status for a whole stack:
for n in <prs>; do
  gh api /repos/camunda/camunda-platform-helm/pulls/$n \
    --jq '"\(.stack.position)/\(.stack.size) #\(.number) draft=\(.draft) \(.title)"'
done

Gotchas

• A correct base chain is not a stack. Always check .stack after creating a PR.
• gh must be recent enough for the extension. gh extension install github/gh-stack failing or gh stack reporting an unknown command means the CLI needs upgrading (brew upgrade gh).
• The bottom PR drifts from main. A long-lived stack's base commit ages; gh stack sync fast-forwards trunk and cascades, and gh stack view marks branches needing a rebase with ⚠.
• Force-pushes invalidate in-progress reviews. Cascade-rebasing rewrites every branch above the change, so batch review rounds rather than rebasing after each comment.
• Keep each layer independently green. A reviewer may check out any single PR; a layer that only passes once a later one lands is mis-split.