Gh Stack Agent Skill

gh-stack

gh stack is a GitHub CLI extension for stacked branches and pull

requests. A stack is an ordered chain of branches rooted on a trunk, where each branch has one PR

based on the branch below it, so a reviewer sees only that layer's diff.

gh stack prints a stack trunk-first, left to right:

(main) <- auth <- api <- frontend

Left is the bottom, right is the top. auth is based on main and merges first;

frontend merges last. up moves toward the top, away from trunk; down moves toward it.

Foundational work belongs at the bottom, code that depends on it above. For how to choose the

layers, read references/stack-design.md.

Setup

gh extension install github/gh-stack
git config rerere.enabled true         # remember conflict resolutions
git config remote.pushDefault origin   # required if the repo has more than one remote

Non-interactive use

gh stack branches on whether stdout is a TTY. Piped, most commands error cleanly or print

static text; under a PTY the same commands open a prompt or a full-screen TUI and block forever.

Agent harnesses differ, so always pass the flags below instead of relying on that detection.

Multiple remotes: never run push, submit, sync, rebase, or link without

--remote <name> unless remote.pushDefault is configured. checkout and trunk have no

--remote flag and require the config.

| Always run | Never run bare | Why |

|---|---|---|

| gh stack view --json | gh stack view | opens a TUI under a PTY |

| gh stack submit --auto | gh stack submit | prompts for a title per new PR |

| gh stack merge <target> --yes | gh pr merge | gh pr merge cannot merge a stack |

| gh stack init <branch>... | gh stack init | prompts for branch names |

| gh stack add <branch> | gh stack add | prompts for a name, and fails even when piped |

| gh stack checkout <target> | gh stack checkout | opens a selection menu |

| gh stack up / down / top / bottom | gh stack switch | switch is menu-only |

| — | gh stack modify | TUI-only, no non-interactive path |

• view --short is safe in both modes, but it is formatted for humans. Use --json to parse.
• checkout <pr> when a different local stack already covers those branches cannot be forced.

Run gh stack unstack --local first (this keeps the stack on GitHub), then retry.

Branch placement

• Starting multi-part work: create the stack before writing files. Do not implement every

concern on trunk and split it later. Put one dependent concern in each layer, bottom to top.

• Editing an existing stack: check out the layer that owns the change before editing. Never

commit a lower layer's concern on the current top branch. Run gh stack view --json; if

ownership is unclear, inspect git log --all -- <path>. Then check out the owner, edit, commit,

rebase upstack, and return to top.

gh stack down                   # or: gh stack checkout api
git add ... && git commit -m "Add get-user endpoint"
gh stack rebase --upstack       # replay every branch above onto the change
gh stack top                    # return to where you were
gh stack push

Core loop

gh stack init auth              # create the stack and check out its branch
git add ... && git commit -m "Add auth middleware"
gh stack add api                # next layer, branched from the current one
git add ... && git commit -m "Add API routes"
gh stack submit --auto          # push every branch and open draft PRs
gh stack view --json            # confirm

Add --open to submit to create PRs ready for review instead of drafts. Branch names are

verbatim — gh stack add refactor/foo creates refactor/foo.

Staying in sync

gh stack sync                   # fetch, reconcile with GitHub, rebase, push, refresh PR state
gh stack sync --prune           # also delete local branches for merged PRs

Pruning never happens without --prune when non-interactive. If the local and remote stacks have

diverged, sync prints both chains, makes no changes, and exits 0 with Sync aborted — see

references/troubleshooting.md.

Merging

Scope the merge with an argument:

gh stack merge 42 --yes          # PR #42 plus every unmerged PR below it
gh stack merge 7 --yes           # every unmerged PR in stack #7
gh stack merge 42 --yes --squash # or --merge, --rebase, --merge-method <method>

Pass a PR number to merge that PR and every unmerged PR below it, or a stack number to merge every

unmerged PR in that stack. The operation is all-or-nothing: if any PR in that set cannot merge,

none do.

Without a method flag the last-used method is reused. If the base branch uses a merge queue, the

stack is queued instead and the queue picks the method, ignoring any flag you passed with a

warning; queued PRs may land in separate groups.

Reading state

gh stack view --json writes JSON to stdout. Status messages go to stderr — do not parse

them, branch on exit codes instead.

trunk           string
currentBranch   string
branches[]      name, head, base, isCurrent, isMerged, isQueued, needsRebase
branches[].pr   number, url, state ("OPEN" | "MERGED" | "QUEUED"); absent when no PR exists

base is the saved SHA of the parent branch that this branch was last known to contain. It may be

older than the parent's current tip. needsRebase is true when the current parent tip is no longer

an ancestor of the branch.

Exit codes

| Code | Meaning | Recovery |

|---|---|---|

| 0 | Success | — |

| 1 | Generic error | Read stderr |

| 2 | Not in a stack | gh stack init, or gh stack checkout <target> |

| 3 | Rebase conflict | Follow the Exit 3 recovery below |

| 4 | GitHub API failure | Check gh auth status, retry |

| 5 | Invalid arguments | Fix the invocation; see <command> --help |

| 6 | Disambiguation required | Branch is in several stacks; check out a non-shared branch |

| 7 | Rebase already in progress | gh stack rebase --continue or --abort |

| 8 | Stack file locked | Another gh stack process is writing; retry after ~5s |

| 9 | Stacked PRs unavailable | Not enabled on the repository; tell the user |

| 10 | Modify recovery required | gh stack modify --abort |

Exit 3 recovery:

• After gh stack rebase: resolve the files, run git add, then

gh stack rebase --continue; use gh stack rebase --abort to restore the stack.

• After gh stack sync: the stack has already been restored. Run gh stack rebase to recreate the

conflict, then resolve and continue as above.

Constraints

• Stacks are strictly linear: one parent, at most one child. Use separate stacks for parallel work.
• There is no non-interactive reorder or removal. Errors may suggest gh stack modify, but it is

TUI-only — restructure with unstack then init instead.

• PR titles and bodies are auto-generated. Use gh pr edit afterwards to change them.
• checkout <branch-name> resolves against local stacks only. Use a stack or PR number to pull a

stack down from GitHub.

More detail

gh stack <command> --help is authoritative for flags and arguments. Note that

gh stack help <command> does not work — it prints the top-level help.

Open the reference whose trigger matches the task; no need to preload all three.

• references/stack-design.md — read before creating a stack, when deciding how many layers to

use, what belongs in each one, or whether work belongs in a new stack.

• references/commands.md — read when a command fails unexpectedly or you need its preconditions,

side effects, atomicity, or ordering guarantees.

• references/troubleshooting.md — read on a rebase conflict, after a squash-merge, on local and

remote divergence, when restructuring a stack, or when driving stacks from another tool.