gh-stack

# gh-stack `gh stack` is a [GitHub CLI](https://cli.github.com/) 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 Requires Git 2.36+ and an authenticated GitHub CLI. ```bash 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. - **Worktrees:** local stacks share one common-directory catalog. Use `--print-path` with navigation or explicit-target `checkout` to locate a foreign-owned branch without stealing its checkout. Unoccupied targets are checked out here first. Check the exit status before changing directories; parse only successful path-mode stdout, never status messages. ## 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. ```bash 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 ```bash 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 ```bash 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: ```bash 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. - `rebase` and `sync` automatically update affected clean worktrees; they never auto-stash or create/remove worktrees. Mutations serialize across the clone, and paused operations require recovery in their recorded owners. - `modify` supports distributed stack branches, but its editor remains TUI-only. Actions run in affected clean owners; unoccupied branches use the origin. Drop/fold source branches and worktrees are preserved. Recovery flags may run from any worktree and use recorded native operation owners; never resolve/stage in the caller's tree unless the diagnostic names it. - 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. ## 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.