catchup

name	catchup
description	Summarize all changes in current branch compared to base branch
argument-hint	[optional: base branch name]
disable-model-invocation	true
allowed-tools	["Read","Bash","Grep","Glob"]

Catchup

Goal

Quickly understand all changes in the current branch by providing a smart summary of commits, changed files, and key modifications. This is optimized for the "restart workflow" - after running /clear, use /catchup to get back up to speed without reading every file.

Input

• $ARGUMENTS (optional): Base branch name to compare against
  • If not provided: auto-detects main, master, or develop
  • Examples: /catchup, /catchup main, /catchup develop

Process

1. Verify Git Repository

Check that we're in a git repository:

git rev-parse --git-dir

If this fails, inform the user this command requires a git repository and exit.

2. Detect Current and Base Branch

# Get current branch
CURRENT_BRANCH=$(git branch --show-current)

# If no argument provided, auto-detect base branch
if [ -z "$ARGUMENTS" ]; then
  # Try to find default branch from remote
  DEFAULT_BRANCH=$(git symbolic-ref refs/remotes/origin/HEAD 2>/dev/null | sed 's@^refs/remotes/origin/@@')

  # Fallback: check if main or master exists
  if [ -z "$DEFAULT_BRANCH" ]; then
    if git show-ref --verify --quiet refs/heads/main; then
      DEFAULT_BRANCH="main"
    elif git show-ref --verify --quiet refs/heads/master; then
      DEFAULT_BRANCH="master"
    elif git show-ref --verify --quiet refs/heads/develop; then
      DEFAULT_BRANCH="develop"
    else
      echo "Could not auto-detect base branch. Please specify: /catchup <base-branch>"
      exit 1
    fi
  fi
  BASE_BRANCH="$DEFAULT_BRANCH"
else
  BASE_BRANCH="$ARGUMENTS"
fi

Verify base branch exists:

if ! git show-ref --verify --quiet refs/heads/$BASE_BRANCH; then
  echo "Error: Base branch '$BASE_BRANCH' does not exist"
  exit 1
fi

3. Check for Changes

Determine if there are any changes:

# Get commit count ahead
COMMITS_AHEAD=$(git rev-list --count $BASE_BRANCH..HEAD)

# Get changed files count
CHANGED_FILES=$(git diff --name-only $BASE_BRANCH...HEAD | wc -l)

If both are zero:

No changes detected between $CURRENT_BRANCH and $BASE_BRANCH.
Branches are in sync.

Exit successfully.

4. Gather Branch Information

Collect comprehensive branch context:

# Commit history (one-line format)
git log --oneline $BASE_BRANCH..HEAD

# Changed files with status
git diff --name-status $BASE_BRANCH...HEAD

# Diff stats (lines added/removed per file)
git diff --stat $BASE_BRANCH...HEAD

# Get uncommitted changes if any
git status --porcelain

5. Organize and Present Summary

Present information in this structured format:

# Branch Catchup: {CURRENT_BRANCH}

## Overview
- **Current Branch**: {CURRENT_BRANCH}
- **Base Branch**: {BASE_BRANCH}
- **Commits Ahead**: {COMMITS_AHEAD}
- **Files Changed**: {total} ({added} added, {modified} modified, {deleted} deleted)
- **Uncommitted Changes**: {Yes/No} ({count} files)

## Commit History

{List commits with hash and message}

## Changed Files by Status

### Added Files
{List of added files}

### Modified Files
{List of modified files with diff stats}

### Deleted Files
{List of deleted files}

## Diff Statistics

{Output from git diff --stat showing lines changed per file}

## Uncommitted Changes
{If any exist, show git status output}

## File Organization

{Group files by directory/component for easier understanding}
Example:
- **Backend (src/)**: 5 files
- **Frontend (ui/)**: 3 files
- **Tests (tests/)**: 2 files
- **Docs (docs/)**: 1 file

## Key Insights

{Analyze commit messages and file changes to provide context}
- Main focus: {infer from commit messages}
- Components affected: {list major areas}
- Potential breaking changes: {flag if file names suggest}

## Next Steps

To see detailed changes in a specific file:
- Use Read tool: `Read path/to/file.py`
- Or git diff: `git diff {BASE_BRANCH}...HEAD -- path/to/file.py`

To resume work:
- Review uncommitted changes if any
- Check TODO list with TodoWrite
- Continue implementation

6. Smart File Reading (Optional)

Only read file contents if:

• There are very few changed files (≤3)
• User explicitly requests more detail
• File changes are unclear from diff stats

Otherwise, trust that the summary provides enough context. The goal is efficiency - reading 20+ files defeats the "quick catchup" purpose.

Error Handling

Not in Git Repository

Error: This command requires a git repository.
Current directory is not a git repository.

Invalid Base Branch

Error: Base branch '{BASE_BRANCH}' does not exist.
Available branches: {list branches}

Usage: /catchup [base-branch-name]

Detached HEAD State

Warning: You are in a detached HEAD state.
Current commit: {hash}
Cannot determine current branch name.

You may want to create a branch first:
git checkout -b my-branch-name

No Commits Yet

This appears to be a new repository with no commits.
Cannot compare branches without commit history.

Output Guidelines

• Be concise: Show summary first, details available on request
• Be organized: Group related files together
• Be actionable: Suggest next steps based on state
• Be accurate: Parse git output carefully, handle edge cases

Usage Examples

# Basic usage - auto-detect base branch
/catchup

# Compare to specific branch
/catchup develop

# Compare to main explicitly
/catchup main

# After /clear to understand current state
/clear
/catchup  # "What have I been working on?"

Integration with Other Commands

This command works well with:

• /clear - Clear state, then /catchup to understand what's there
• /handoff - After /catchup, use /handoff to document work
• /create-pr - After /catchup, review changes before creating PR
• /check-ci - After /catchup, ensure tests pass

Final Instructions

1. Keep output under 1000 lines for readability
2. If diff is huge (>50 files), show summary stats only
3. Focus on commits and high-level changes, not line-by-line diffs
4. Make it easy to quickly understand branch state in under 30 seconds
5. Provide file paths in a format that can be easily copied for Read tool