Supporting Scripts

Branch Preparation Script

Create scripts/prepare-branch.sh for idempotent branch management:

#!/bin/bash
set -e

# Usage: prepare-branch.sh <branch_name> <default_branch>

BRANCH_NAME="$1"
DEFAULT_BRANCH="$2"

if [ -z "$BRANCH_NAME" ] || [ -z "$DEFAULT_BRANCH" ]; then
  echo "Usage: $0 <branch_name> <default_branch>"
  exit 1
fi

# Configure git authentication
if [ -n "$GH_TOKEN" ]; then
  git config --local credential.helper \
    '!f() { echo "username=x-access-token"; echo "password=$GH_TOKEN"; }; f'
fi

git fetch origin

if git ls-remote --heads origin "$BRANCH_NAME" | grep -q "$BRANCH_NAME"; then
  echo "Branch exists remotely, resetting to remote state..."
  git checkout -B "$BRANCH_NAME" "origin/$BRANCH_NAME"
elif git branch --list "$BRANCH_NAME" | grep -q "$BRANCH_NAME"; then
  echo "Branch exists locally, checking out..."
  git checkout "$BRANCH_NAME"
else
  echo "Creating new branch from $DEFAULT_BRANCH..."
  git checkout -b "$BRANCH_NAME"
fi

Script Features

Idempotency: Uses git checkout -B to force reset to remote state, avoiding merge conflicts on subsequent runs.

Git Authentication

The script automatically configures git credentials when GH_TOKEN is set:

git config --local credential.helper \
  '!f() { echo "username=x-access-token"; echo "password=$GH_TOKEN"; }; f'

This allows push operations to use the GitHub App token.

Branch State Handling

Scenario	Action
Branch exists remotely	Reset to remote state
Branch exists locally only	Checkout local branch
Branch doesn't exist	Create from default branch