Simple script that checks out a pull request from GitHub into its own worktree

pr_checkout.bash

function pr_checkout() {
  # Get current repo info
  local repo
  repo=$(gh repo view --json nameWithOwner -q .nameWithOwner 2>/dev/null)
  if [[ -z $repo ]]; then
    echo "Error: Not in a GitHub repository or gh CLI not authenticated"
    return 1
  fi

  echo "Fetching open PRs for $repo..."

  # Get PRs with format: "#123 | PR Title | author | branch"
  local pr_list
  pr_list=$(gh pr list --state open --json number,title,headRefName,author --template '{{range .}}#{{.number}} | {{.title}} | {{.author.login}} | {{.headRefName}}{{"\n"}}{{end}}')

  if [[ -z $pr_list ]]; then
    echo "No open PRs found"
    return 0
  fi

  # Use fzf to select a PR
  local selected
  selected=$(echo "$pr_list" | fzf --height=20 --header="Select a PR to checkout:" --preview='echo {}' --preview-window=down:3:wrap)

  if [[ -z $selected ]]; then
    echo "No PR selected"
    return 0
  fi

  # Extract PR number and branch name
  local pr_number branch_name pr_title
  pr_number=$(echo "$selected" | cut -d'|' -f1 | sed 's/#//' | xargs)
  branch_name=$(echo "$selected" | cut -d'|' -f4 | xargs)
  pr_title=$(echo "$selected" | cut -d'|' -f2 | xargs)

  local base_branch
  base_branch=$(gh pr view "$pr_number" --json baseRefName -q .baseRefName)

  echo "Selected PR #$pr_number: $pr_title"
  echo "Branch: $branch_name"
  echo "Base branch: $base_branch"

  # Create worktree directory name (sanitize for filesystem)
  local worktree_name worktree_path
  worktree_name="pr-${pr_number}-${branch_name//[^a-zA-Z0-9-]/-}"
  worktree_path="../$worktree_name"

  # Check if worktree already exists
  if [[ -d $worktree_path ]]; then
    echo "Worktree already exists at $worktree_path"
    read -p "Do you want to switch to it? (y/N): " -n 1 -r
    echo
    if [[ $REPLY =~ ^[Yy]$ ]]; then
      pushd "$worktree_path" || return 1
      echo "Switched to existing worktree: $worktree_path"
    fi
    return 0
  fi

  echo "Creating worktree at $worktree_path..."

  # Fetch the PR branch and create worktree
  if gh pr checkout "$pr_number" --detach 2>/dev/null; then
    # If gh pr checkout works, create worktree from the checked out state
    git worktree add "$worktree_path" HEAD
    git checkout - # Go back to original branch
  else
    # Fallback: fetch and create worktree manually
    git fetch origin "$branch_name:$branch_name" 2>/dev/null || git fetch origin "pull/$pr_number/head:$branch_name"
    git worktree add "$worktree_path" "$branch_name"
  fi

  git fetch origin "$base_branch"

  # shellcheck disable=SC2181 # I am too lazy
  if [[ $? -eq 0 ]]; then
    echo "Successfully created worktree for PR #$pr_number"
    echo "Switching to worktree..."
    pushd "$worktree_path" || return 1
    # Mixed reset to the merge base so that the diff matches GitHub even if the PR is behind base branch
    git reset --mixed "$(git merge-base "origin/$base_branch" "origin/$branch_name")"
    echo "Current directory: $(pwd)"
    echo "Current branch: $(git branch --show-current)"
  else
    echo "Failed to create worktree"
    return 1
  fi
}