/pr-auto-update

description: 'Auto-update PR description and labels from changes. Trigger with "update PR description", "refresh PR", "update labels".'
allowed-tools:
  - Bash(gh *)
  - Bash(git *)
  - Read
  - Grep
  - Glob

Auto-update PR description and labels from changes

Overview

A command that automatically updates Pull Request descriptions and labels. Analyzes Git changes to generate and set appropriate descriptions and labels.

Usage

/pr-auto-update [options] [PR number]

Options

• `--pr <number>`: Specify target PR number (automatically detected from current branch if omitted)
• `--description-only`: Update only the description (keep labels unchanged)
• `--labels-only`: Update only labels (keep description unchanged)
• `--dry-run`: Show generated content without making actual updates
• `--lang <language>`: Specify language (en)

Basic Examples

# Auto-update PR for current branch
/pr-auto-update

# Update specific PR
/pr-auto-update --pr 1234

# Update description only
/pr-auto-update --description-only

# Check with dry-run
/pr-auto-update --dry-run

Feature Details

1. PR Auto Detection

Automatically detects the corresponding PR from the current branch:

# Search PR from branch
gh pr list --head $(git branch --show-current) --json number,title,url

2. Change Analysis

Collects and analyzes the following information:

• **File changes**: Added, deleted, or modified files
• **Code analysis**: Changes to imports, function definitions, class definitions
• **Tests**: Presence and content of test files
• **Documentation**: Updates to README, docs
• **Configuration**: Changes to package.json, pubspec.yaml, configuration files
• **CI/CD**: Changes to GitHub Actions, workflows

3. Automatic Description Generation

Template Processing Priority

1. **Existing PR description**: Completely follows already written content 2. **Project template**: Gets structure from `.github/PULL_REQUEST_TEMPLATE.md` 3. **Default template**: Fallback when above don't exist

Rules for Preserving Existing Content

**Important**: Do not modify existing content

• Keep existing sections
• Only complete empty sections
• Keep functional comments (like Copilot review rules)

Using Project Templates

# Parse structure of .github/PULL_REQUEST_TEMPLATE.md
parse_template_structure() {
  local template_file="$1"

  if [ -f "$template_file" ]; then
    # Extract section structure
    grep -E '^##|^###' "$template_file"

    # Identify comment placeholders
    grep -E '<!--.*-->' "$template_file"

    # Completely follow existing template structure
    cat "$template_file"
  fi
}

4. Automatic Label Setting

Label Retrieval Mechanism

**Priority**:

1. **`.github/labels.yml`**: Get from project-specific label definitions 2. **GitHub API**: Get existing labels with `gh api repos/{OWNER}/{REPO}/labels --jq '.[].name'`

Automatic Determination Rules

**File Pattern Based**:

• Documentation: `*.md`, `README`, `docs/` → labels containing `documentation|docs|doc`
• Tests: `test`, `spec` → labels containing `test|testing`
• CI/CD: `.github/`, `*.yml`, `Dockerfile` → labels containing `ci|build|infra|ops`
• Dependencies: `package.json`, `pubspec.yaml`, `requirements.txt` → labels containing `dependencies|deps`

**Change Content Based**:

• Bug fixes: `fix|bug|error|crash|correction` → labels containing `bug|fix`
• New features: `feat|feature|add|implement|new-feature|implementation` → labels containing `feature|enhancement|feat`
• Refactoring: `refactor|clean|restructure` → labels containing `refactor|cleanup|clean`
• Performance: `performance|perf|optimize|optimization` → labels containing `performance|perf`
• Security: `security|secure|vulnerability` → labels containing `security`

Constraints

• **Maximum 3**: Upper limit on automatically selected labels
• **Existing labels only**: Creating new labels is prohibited
• **Partial match**: Determined by whether keywords are contained in label names

Actual Usage Examples

**When `.github/labels.yml` exists**:

# Auto-retrieve from label definitions
grep "^- name:" .github/labels.yml | sed "s/^- name: '\?\([^']*\)'\?/\1/"

# Example: Use project-specific label system

**When retrieving from GitHub API**:

# Get list of existing labels
gh api repos/{OWNER}/{REPO}/labels --jq '.[].name'

# Example: Use standard labels like bug, enhancement, documentation

5. Execution Flow

#!/bin/bash

# 1. PR Detection & Retrieval
detect_pr() {
  if [ -n "$PR_NUMBER" ]; then
    echo $PR_NUMBER
  else
    gh pr list --head $(git branch --show-current) --json number --jq '.[0].number'
  fi
}

# 2. Change Analysis
analyze_changes() {
  local pr_number=$1

  # Get file changes
  gh pr diff $pr_number --name-only

  # Content analysis
  gh pr diff $pr_number | head -1000
}

# 3. Description Generation
generate_description() {
  local pr_number=$1
  local changes=$2

  # Get current PR description
  local current_body=$(gh pr view $pr_number --json body --jq -r .body)

  # Use existing content if available
  if [ -n "$current_body" ]; then
    echo "$current_body"
  else
    # Generate new from template
    local template_file=".github/PULL_REQUEST_TEMPLATE.md"
    if [ -f "$template_file" ]; then
      generate_from_template "$(cat "$template_file")" "$changes"
    else
      generate_from_template "" "$changes"
    fi
  fi
}

# Generate from template
generate_from_template() {
  local template="$1"
  local changes="$2"

  if [ -n "$template" ]; then
    # Use template as-is (preserve HTML comments)
    echo "$template"
  else
    # Generate in default format
    echo "## What does this change?"
    echo ""
    echo "$changes"
  fi
}

# 4. Label Determination
determine_labels() {
  local changes=$1
  local file_list=$2
  local pr_number=$3

  # Get available labels
  local available_labels=()
  if [ -f ".github/labels.yml" ]; then
    # Extract label names from labe