Imported from villads-valur/vanluren (claude/skills/stacking-pr/SKILL.md). Install upstream with npx skills add villads-valur/vanluren --skill stacking-pr. Copyright stays with the author.

gh-stack

gh stack is a GitHub CLI extension for managing stacked branches and pull requests. A stack is an ordered list of branches where each branch builds on the one below it, rooted on a trunk branch (typically the repo's default branch). Each branch maps to one PR whose base is the branch below it, so reviewers see only the diff for that layer.

main (trunk)
 └── feat/auth-layer     → PR #1 (base: main)               - bottom (closest to trunk)
  └── feat/api-endpoints → PR #2 (base: feat/auth-layer)
   └── feat/frontend     → PR #3 (base: feat/api-endpoints) - top (furthest from trunk)

The bottom of the stack is the branch closest to the trunk, and the top is the branch furthest from the trunk. Each branch inherits from the one below it. Navigation commands (up, down, top, bottom) follow this model: up moves away from trunk, down moves toward it.

When to use this skill

Use this skill when the user wants to:

• Break a large change into a chain of small, reviewable PRs
• Create, rebase, push, or sync a stack of dependent branches
• Navigate between layers of a branch stack
• View the status of stacked PRs
• Tear down and rebuild a stack to remove, reorder, or rename branches

Prerequisites

The GitHub CLI (gh) v2.0+ must be installed and authenticated. Install the extension with:

gh extension install github/gh-stack

Before using gh stack, configure git to prevent interactive prompts:

git config rerere.enabled true           # remember conflict resolutions (skips prompt on init)
git config remote.pushDefault origin     # if multiple remotes exist (skips remote picker)

Agent rules

All gh stack commands must be run non-interactively. Every command invocation must include the flags and positional arguments needed to avoid prompts, TUIs, and interactive menus. If a command would prompt for input, it will hang indefinitely.

1. Always supply branch names as positional arguments to init, add, and checkout. Running these commands without arguments triggers interactive prompts.
2. When a prefix is set, pass only the suffix to add. gh stack add auth with prefix feat → feat/auth. Passing feat/auth creates feat/feat/auth.
3. Always use --auto with gh stack submit to auto-generate PR titles. Without --auto, submit prompts for a title for each new PR.
4. Always use --json with gh stack view. Without --json, the command launches an interactive TUI that cannot be operated by agents. There is no other appropriate flag — always pass --json.
5. Use --remote <name> when multiple remotes are configured, or pre-configure git config remote.pushDefault origin. Without this, push, submit, sync, and checkout trigger an interactive remote picker.
6. Avoid branches shared across multiple stacks. If a branch belongs to multiple stacks, commands exit with code 6. Check out a non-shared branch first.
7. Plan your stack layers by dependency order before writing code. Foundational changes (models, APIs, shared utilities) go in lower branches; dependent changes (UI, consumers) go in higher branches. Think through the dependency chain before running gh stack init.
8. Use standard git add and git commit for staging and committing. This gives you full control over which changes go into each branch. The -Am shortcut is available but should not be the default approach—stacked PRs are most effective when each branch contains a deliberate, logical set of changes.
9. Navigate down the stack when you need to change a lower layer. If you're working on a frontend branch and realize you need API changes, don't hack around it at the current layer. Navigate to the appropriate branch (gh stack down, gh stack checkout, or gh stack bottom), make and commit the changes there, run gh stack rebase --upstack, then navigate back up to continue.

Never do any of the following — each triggers an interactive prompt or TUI that will hang:

• ❌ gh stack view or gh stack view --short — always use gh stack view --json
• ❌ gh stack submit without --auto — always use gh stack submit --auto
• ❌ gh stack init without branch arguments — always provide branch names
• ❌ gh stack add without a branch name — always provide a branch name
• ❌ gh stack checkout without an argument — always provide a PR number or branch name
• ❌ gh stack checkout <pr-number> when a different local stack already exists on those branches — this triggers an unbypassable conflict resolution prompt; use gh stack unstack first to remove the local stack, then retry the checkout

Thinking about stack structure

Each branch in a stack should represent a discrete, logical unit of work that can be reviewed independently. The changes within a branch should be cohesive—they belong together and make sense as a single PR.

Dependency chain

Stacked branches form a dependency chain: each branch builds on the one below it. This means foundational changes must go in lower (earlier) branches, and code that depends on them goes in higher (later) branches.

Plan your layers before writing code. For example, a full-stack feature might be structured like this (use branch names relevant to your actual task, not these generic ones):

main (trunk)
 └── feat/data-models    ← shared types, database schema
  └── feat/api-endpoints ← API routes that use the models
   └── feat/frontend-ui  ← UI components that call the APIs
    └── feat/integration ← tests that exercise the full stack

This is illustrative — choose branch names and layer boundaries that reflect the specific work you're doing. The key principle is: if code in one layer depends on code in another, the dependency must be in the same branch or a lower one.

Branch naming

Prefer initializing stacks with a prefix (-p). Prefixes group branches under a namespace (e.g., feat/auth, feat/api) and keep branch names clean and consistent. When a prefix is set, pass only the suffix to subsequent add calls — the prefix is applied automatically. Without a prefix, you'll need to pass the full branch name each time.

Staging changes deliberately

The main reason to use git add and git commit directly is to control which changes go into which branch. When you have multiple files in your working tree, you can stage a subset for the current branch, commit them, then create a new branch and stage the rest there:

# You're on feat/data-models with several new files in your working tree.
# Stage only the model files for this branch:
git add internal/models/user.go internal/models/session.go
git commit -m "Add user and session models"

git add db/migrations/001_create_users.sql
git commit -m "Add user table migration"

# Now create a new branch for the API layer and stage the API files there:
gh stack add api-routes # created & switched to feat/api-routes branch
git add internal/api/routes.go internal/api/handlers.go
git commit -m "Add user API routes"

This keeps each branch focused on one concern. Multiple commits per branch are fine — the key is that all commits in a branch relate to the same logical concern, and changes that belong to a different concern go in a different branch.

When to create a new branch

Create a new branch (gh stack add) when you're starting a different concern that depends on what you've built so far. Signs it's time for a new branch:

• You're switching from backend to frontend work
• You're moving from core logic to tests or documentation
• The next set of changes has a different reviewer audience
• The current branch's PR is already large enough to review

One stack, one story

Think of a stack from the reviewer's perspective: the stack of PRs should tell a cohesive story about a feature or project. A reviewer should be able to read the PRs in sequence and understand the progression of changes, with each PR being a small, logical piece of the whole.

When to use a single stack: All the branches are part of the same feature, project, or closely related effort. Even if the work spans multiple concerns (models, API, frontend), they're all building toward the same goal.

When to create a separate stack: The work is unrelated to your current stack — a different feature, a bug fix in an unrelated area, or an independent refactor. Don't mix unrelated work into a single stack just because you happen to be working on both. Start a new stack with gh stack init or switch to an existing stack with gh stack checkout for each distinct effort.

Small, incidental fixes (e.g., fixing a typo you noticed) can go in the current stack if they're trivial. But if a change grows into its own project, it deserves its own stack.

Quick reference

Workflows

End-to-end: create a stack from scratch

# 1. Initialize a stack with the first branch
gh stack init -p feat auth
# → creates feat/auth and checks it out

# 2. Write code for the first layer (auth)
cat > auth.go << 'EOF'
package auth

func Middleware(next http.Handler) http.Handler {
    return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
        // verify token
        next.ServeHTTP(w, r)
    })
}
EOF

# 3. Stage and commit using standard git commands
git add auth.go
git commit -m "Add auth middleware"

# You can make multiple commits on the same branch
cat > auth_test.go << 'EOF'
package auth

func TestMiddleware(t *testing.T) {
    // test auth middleware
}
EOF
git add auth_test.go
git commit -m "Add auth middleware tests"

# 4. When you're ready for a new concern, add the next branch
gh stack add api-routes
# → creates feat/api-routes (prefix applied automatically — just pass the suffix)

# 5. Write code for the API layer
cat > api.go << 'EOF'
package api

func RegisterRoutes(mux *http.ServeMux) {
    mux.HandleFunc("/users", handleUsers)
}
EOF
git add api.go
git commit -m "Add API routes"

# 6. Add a third layer for frontend
gh stack add frontend
# → creates feat/frontend (just the suffix — prefix is automatic)

cat > frontend.go << 'EOF'
package frontend

func RenderDashboard(w http.ResponseWriter) {
    // calls the API endpoints from the layer below
}
EOF
git add frontend.go
git commit -m "Add frontend dashboard"

# ── Stack complete: feat/auth → feat/api-routes → feat/frontend ──

# 7. Push everything and create draft PRs
gh stack submit --auto --draft

# 8. Verify the stack
gh stack view --json

Shortcut: If you prefer a faster flow, gh stack add -Am "message" branch-name combines staging, committing, and branch creation into one command. This is useful for single-commit layers but bypasses deliberate staging.

Making mid-stack changes

This is a critical workflow for agents. When you're working on a higher layer and realize you need to change something in a lower layer (e.g., you're building frontend components but need to add an API endpoint), navigate down to the correct branch, make the change there, and rebase.

# You're on feat/frontend but need to add an API endpoint

# 1. Navigate to the API branch
gh stack down
# or: gh stack checkout feat/api-routes

# 2. Make the change where it belongs
cat > users_api.go << 'EOF'
package api

func handleGetUser(w http.ResponseWriter, r *http.Request) {
    // new endpoint the frontend needs
}
EOF
git add users_api.go
git commit -m "Add get-user endpoint"

# 3. Rebase everything above to pick up the change
gh stack rebase --upstack

# 4. Navigate back to where you were working
gh stack top
# or: gh stack checkout feat/frontend

# 5. Continue working — the API changes are now available

Why this matters: If you make API changes on the frontend branch, those changes will end up in the wrong PR. The API PR won't include them, and the frontend PR will have unrelated API diffs mixed in. Always put changes in the branch where they logically belong.

Modify a mid-stack branch and sync

When you need to revisit a branch after the initial creation (e.g., responding to review feedback):

# 1. Navigate to the branch that needs changes
gh stack bottom
# or: gh stack checkout feat/auth
# or: gh stack checkout 42  (by PR number)

# 2. Make changes and commit
cat > auth.go << 'EOF'
package auth
// updated implementation
EOF
git add auth.go
git commit -m "Fix auth token validation"

# 3. Rebase everything above this branch
gh stack rebase --upstack

# 4. Push the updated stack
gh stack push

Routine sync after merges

# Single command: fetch, rebase, push, sync PR state
gh stack sync

Squash-merge recovery

When a PR is squash-merged on GitHub, the original branch's commits no longer exist in the trunk history. gh stack detects this automatically and uses git rebase --onto to correctly replay remaining commits.

# After PR #1 (feat/auth) is squash-merged on GitHub:
gh stack sync
# → fetches latest, detects the merge, fast-forwards trunk
# → rebases feat/api-routes onto updated trunk (skips merged branch)
# → rebases feat/frontend onto feat/api-routes
# → pushes updated branches
# → reports: "Merged: #1"

# Verify the result
gh stack view --json
# → feat/auth shows "isMerged": true, "state": "MERGED"
# → feat/api-routes and feat/frontend show updated heads

If sync hits a conflict during this process, it restores all branches to their pre-rebase state and exits with code 3. See Handle rebase conflicts for the resolution workflow.

Handle rebase conflicts (agent workflow)

# 1. Start the rebase
gh stack rebase

# 2. If exit code 3 (conflict):
#    - Parse stderr for conflicted file paths
#    - Read those files to find <<<<<<< / ======= / >>>>>>> markers
#    - Edit files to resolve conflicts
#    - Stage resolved files:
git add path/to/resolved-file.go

# 3. Continue the rebase
gh stack rebase --continue

# 4. If another conflict occurs, repeat steps 2-3

# 5. If unable to resolve, abort to restore everything
gh stack rebase --abort

Parsing --json output

# Get stack state as JSON
output=$(gh stack view --json)

# Check if any branch needs a rebase, and rebase if so
needs_rebase=$(echo "$output" | jq '[.branches[] | select(.needsRebase == true)] | length')
if [ "$needs_rebase" -gt 0 ]; then
  echo "Branches need rebase, rebasing stack..."
  gh stack rebase
fi

# Get all open PR URLs
echo "$output" | jq -r '.branches[] | select(.pr.state == "OPEN") | .pr.url'

# Find merged branches
echo "$output" | jq -r '.branches[] | select(.isMerged == true) | .name'

# Get the current branch
echo "$output" | jq -r '.currentBranch'

# Check if the stack is fully merged (all branches merged)
echo "$output" | jq '[.branches[] | .isMerged] | all'

Restructure a stack (remove a branch, reorder, or rename)

Use unstack to tear down the stack, make structural changes, then re-init:

# 1. Remove the stack (locally and on GitHub)
gh stack unstack

# 2. Make structural changes — e.g. delete a branch, reorder, rename
git branch -m old-branch-1 new-branch-1

# 3. Re-create the stack with the new structure
gh stack init --base main --adopt new-branch-1 new-branch-2 new-branch-3

Commands

Initialize a stack — gh stack init

Creates a new stack. Always provide at least one branch name as a positional argument — running without branch arguments triggers interactive prompts that agents cannot use.

gh stack init [flags] <branches...>

# Set a branch prefix (recommended — subsequent `add` calls only need the suffix)
gh stack init -p feat auth
# → creates feat/auth

# Multi-part prefix (slashes are fine — suffix-only rule still applies)
gh stack init -p monalisa/billing auth
# → creates monalisa/billing/auth

# Create a stack with new branches (no prefix — use full branch names)
gh stack init branch-a branch-b branch-c

# Use a different trunk branch
gh stack init --base develop branch-a branch-b

# Adopt existing branches into a stack
gh stack init --adopt branch-a branch-b branch-c

Behavior:

• Using -p is recommended — it simplifies branch naming for subsequent add calls
• Creates any branches that don't already exist (branching from the trunk branch)
• In --adopt mode: validates all branches exist, rejects if any is already in a stack or has an existing PR
• Checks out the last branch in the list
• Enables git rerere so conflict resolutions are remembered across rebases. On first run in a repo, this may trigger a confirmation prompt — pre-configure with git config rerere.enabled true to avoid it

Add a branch — gh stack add

Add a new branch on top of the current stack. Must be run while on the topmost branch (or the trunk if the stack has no branches yet). Always provide a branch name — running without one triggers an interactive prompt.

gh stack add [flags] <branch>

Recommended workflow — create the branch, then use standard git:

# Create a new branch and switch to it (just the suffix — prefix is applied automatically)
gh stack add api-routes

# Write code, stage deliberately, and commit
git add internal/api/routes.go internal/api/handlers.go
git commit -m "Add user API routes"

# Make more commits on the same branch as needed
git add internal/api/middleware.go
git commit -m "Add rate limiting middleware"

Shortcut — stage, commit, and branch in one command:

# Create a new branch, stage all changes, and commit
gh stack add -Am "Add API routes" api-routes

# Create a new branch, stage tracked files only, and commit
gh stack add -um "Fix auth bug" auth-fix

Behavior notes:

• -A and -u are mutually exclusive.
• When the current branch has no commits (e.g., right after init), add -Am commits directly on the current branch instead of creating a new one.
• Prefix handling: Only pass the suffix when a prefix is set. gh stack add api with prefix todo → todo/api. Passing todo/api creates todo/todo/api. Without a prefix, pass the full branch name.
• If called from a branch that is not the topmost in the stack, exits with code 5: "can only add branches on top of the stack". Use gh stack top to switch first.
• Uncommitted changes: When using gh stack add branch-name without -Am, any uncommitted changes (staged or unstaged) in your working tree carry over to the new branch. This is standard git behavior — the working tree is not touched. Commit or stash changes on the current branch before running add if you want a clean starting point on the new branch.

Push branches to remote — gh stack push

Push all stack branches to the remote.

gh stack push [flags]

# Push all branches
gh stack push

# Push to specific remote
gh stack push --remote upstream

Behavior:

• Pushes all active (non-merged) branches atomically (--force-with-lease --atomic)
• Does not create or update pull requests — use gh stack submit for that

Output (stderr):

• Pushed N branches summary

Submit branches and create PRs — gh stack submit

Push all stack branches and create PRs on GitHub. Always pass --auto — without it, submit prompts for a PR title for each new branch.

# Submit and auto-title new PRs (required for non-interactive use)
gh stack submit --auto

# Submit and create PRs as drafts
gh stack submit --auto --draft

Behavior:

• Pushes all active (non-merged) branches atomically (--force-with-lease --atomic)
• Creates a new PR for each branch that doesn't have one (base set to the first non-merged ancestor branch)
• After creating PRs, links them together as a Stack on GitHub (requires the repository to have stacks enabled)
• Syncs PR metadata for branches that already have PRs

PR title auto-generation (--auto):

• Single commit on branch → uses the commit subject as the PR title, commit body as PR body
• Multiple commits on branch → humanizes the branch name (hyphens/underscores → spaces) as the title

Output (stderr):

• Created PR #N for <branch> for each newly created PR
• PR #N for <branch> is up to date for existing PRs
• Pushed and synced N branches summary

Sync the stack — gh stack sync

Fetch, rebase, push, and sync PR state in a single command. This is the recommended command for routine synchronization.

gh stack sync [flags]

What it does (in order):

1. Fetch latest changes from the remote
2. Fast-forward trunk to match remote (skips if already up to date, warns if diverged)
3. Cascade rebase all stack branches onto their updated parents (only if trunk moved). Handles squash-merged PRs automatically. If a conflict is detected, all branches are restored to their pre-rebase state and the command exits with code 3 — see Handle rebase conflicts for the resolution workflow
4. Push all active branches atomically
5. Sync PR state from GitHub and report the status of each PR

Output (stderr):

• ✓ Fetched latest changes from origin
• ✓ Trunk main fast-forwarded to <sha> or ✓ Trunk main is already up to date
• ✓ Rebased <branch> onto <base> per branch (if base moved)
• ✓ Pushed N branches
• ✓ PR #N (<branch>) — Open per branch
• Merged: #N, #M for merged branches
• ✓ Stack synced

Rebase the stack — gh stack rebase

Pull from remote and cascade-rebase stack branches. Use this when sync reports a conflict or when you need finer control (e.g., rebase only part of the stack).

gh stack rebase [flags] [branch]

# Rebase the entire stack
gh stack rebase

# Rebase only branches from trunk to current branch
gh stack rebase --downstack

# Rebase only branches from current branch to top
gh stack rebase --upstack

# After resolving a conflict: stage files with `git add`, then:
gh stack rebase --continue

# Abort and restore all branches to pre-rebase state
gh stack rebase --abort

Conflict handling: See Handle rebase conflicts in the Workflows section for the full resolution workflow.

Squash-merge detection: If a branch's PR was squash-merged on GitHub, the rebase automatically handles this and correctly replays commits on top of the merge target.

Rerere (conflict memory): git rerere is enabled by init so previously resolved conflicts are auto-resolved in future rebases.

View the stack — gh stack view

Display the current stack's branches, PR status, and recent commits. Always pass --json — without it, this command launches an interactive TUI that agents cannot operate.

# Always use --json
gh stack view --json

--json output format:

{
  "trunk": "main",
  "prefix": "feat",
  "currentBranch": "feat/api-routes",
  "branches": [
    {
      "name": "feat/auth",
      "head": "abc1234...",
      "base": "def5678...",
      "isCurrent": false,
      "isMerged": true,
      "needsRebase": false,
      "pr": {
        "number": 42,
        "url": "https://github.com/owner/repo/pull/42",
        "state": "MERGED"
      }
    },
    {
      "name": "feat/api-routes",
      "head": "789abcd...",
      "base": "abc1234...",
      "isCurrent": true,
      "isMerged": false,
      "needsRebase": false,
      "pr": {
        "number": 43,
        "url": "https://github.com/owner/repo/pull/43",
        "state": "OPEN"
      }
    }
  ]
}

Fields per branch:

• name — branch name
• head — current HEAD SHA
• base — parent branch's HEAD SHA at last sync
• isCurrent — whether this is the checked-out branch
• isMerged — whether the PR has been merged
• needsRebase — whether the base branch is not an ancestor (non-linear history)
• pr — PR metadata (omitted if no PR exists). state is "OPEN" or "MERGED".

Navigate the stack

Move between branches without remembering branch names. These commands are fully non-interactive.

gh stack up          # Move up one branch (further from trunk)
gh stack up 3        # Move up three branches
gh stack down        # Move down one branch (closer to trunk)
gh stack down 2      # Move down two branches
gh stack top         # Jump to the top of the stack (furthest from trunk)
gh stack bottom      # Jump to the bottom (first non-merged branch above trunk)

Navigation clamps to stack bounds. Merged branches are skipped when navigating from active branches.

Check out a stack — gh stack checkout

Check out a stack from a pull request number or branch name. Always provide an argument — running gh stack checkout without arguments triggers an interactive selection menu.

gh stack checkout <pr-number | branch>

# By PR number (pulls from GitHub)
gh stack checkout 42

# By branch name (local only)
gh stack checkout feature-auth

When a PR number is provided (e.g. 123), the command fetches the stack on GitHub, pulls the branches, and sets up the stack locally. If the stack already exists locally and matches, it switches to the branch.

⚠️ Agent warning: If the local and remote stacks have different branch compositions, this command triggers an interactive conflict-resolution prompt that cannot be bypassed with a flag. To avoid this: run gh stack unstack first to remove the conflicting local stack, then retry gh stack checkout <pr-number>.

When a branch name is provided, the command resolves it against locally tracked stacks only. This is always safe for non-interactive use.

Remove a stack — gh stack unstack

Tear down a stack so you can restructure it — remove a branch, reorder branches, rename branches, or make other large changes. After unstacking, use gh stack init to re-create the stack with the desired structure.

gh stack unstack [flags] [branch]

# Tear down the stack (locally and on GitHub), then rebuild
gh stack unstack
gh stack init --base main --adopt branch-2 branch-1 branch-3 # reordered

# Only remove local tracking (keep the stack on GitHub)
gh stack unstack --local

# Specify a branch to identify which stack to tear down
gh stack unstack feature-auth

Output conventions

• Status messages go to stderr with emoji prefixes: ✓ (success), ✗ (error), ⚠ (warning), ℹ (info).
• Data output (e.g., view --json) goes to stdout.
• When piping output, use 2>/dev/null to suppress status messages if only data output is needed.

Exit codes and error recovery

Known limitations

1. Stacks are strictly linear. Branching stacks (multiple children on a single parent) are not supported. Each branch has exactly one parent and at most one child. If you need parallel workstreams, use separate stacks.
2. Stack disambiguation cannot be bypassed. If the current branch is the trunk of multiple stacks, commands error with code 6. Check out a non-shared branch first.
3. Multiple remotes require --remote or config. If more than one remote is configured, pass --remote <name> or set remote.pushDefault in git config before running push, sync, or rebase.
4. Merging PRs: Merging Stacked PRs from the CLI is not supported yet. Direct users to open the PR URL in a browser to merge PRs.
5. Remote stack checkout requires a PR number. checkout with a branch name only works with locally tracked stacks. Use a PR number (e.g. gh stack checkout 123) to pull stacks from GitHub.
6. PR title and body are auto-generated. There is no flag to set a custom PR title or body during submit. The title and body are generated from commit messages plus a footer. Use gh pr edit to modify PR title and body after creation.