Generate Commit Message Skill

Overview

This skill generates concise, meaningful commit messages by:

1. First priority: Use conversation context (files edited, changes discussed)
2. Fallback: Run git diff when context is unavailable
3. Keep messages brief and focused

When to Use

• After implementing changes discussed in the conversation
• When you want a commit message that reflects the actual work done
• To quickly commit without manual message writing

Usage

Simply invoke this skill after making changes. The skill will:

1. Check conversation context for what was changed
2. If no context: run git diff --cached to analyze changes
3. Generate a concise commit message
4. Prompt for user confirmation before committing

Commit Message Format

<type>: <brief summary (<=50 chars)>

[Optional body: concise explanation of what/why, <=3 lines]

[Optional footer: Breaking changes, issue refs]

Type Prefixes

• feat: New feature
• fix: Bug fix
• refactor: Code restructure without behavior change
• perf: Performance improvement
• docs: Documentation only
• style: Formatting, whitespace
• test: Add/update tests
• chore: Build, tools, dependencies
• build: Build system changes
• ci: CI/CD changes

Implementation Guidelines

Step 1: Check Conversation Context

Has context if:

• Files were edited via Write/Edit tools in this conversation
• User described what was changed
• Features/fixes were discussed

No context if:

• User just says "commit my changes" without prior discussion
• Changes were made outside this conversation
• Files were modified manually by user

Step 2: Get Change Information

If context available:

• Use known file edits and changes
• Skip git diff entirely

If no context:

# Get list of changed files with status
git diff --cached --name-status

# Get file-level stats
git diff --cached --stat

# Get actual changes (for understanding what was done)
git diff --cached

# Alternative: if nothing staged, check working directory
git status --short
git diff --stat
git diff

Step 3: Generate Concise Message

Principles:

• Brevity: Summary <=50 chars, body <=3 lines
• What, not how: Describe the outcome, not implementation
• Imperative mood: add, fix, update (not added, fixed)

Good Examples:

feat: add scroll limit config commands

Add get-scroll-settings and set-scroll-limit commands
to es_tool.sh for managing ES scroll configuration.

fix: ensure bulk requests end with newline

ES bulk API requires NDJSON format with trailing newline.

refactor: translate es_tool comments to English

Bad Examples:

feat: implement comprehensive elasticsearch scroll configuration management system

This commit adds a full suite of commands for managing scroll-related
settings in Elasticsearch including viewing current configuration,
modifying document count limits, enabling/disabling rejection behavior...
[TOO VERBOSE]

Step 4: Present and Confirm

# Show what will be committed
git status --short

# Present message
echo "Proposed commit message:"
echo "----------------------------------------"
echo "<generated_message>"
echo "----------------------------------------"
echo ""
read -p "Commit these changes? (y/n): " response

Step 5: Execute Commit

CRITICAL: The commit message MUST be clean and professional. DO NOT include:

• 🤖 Generated with [Claude Code] markers
• Co-Authored-By: Claude attributions
• Any other tool-generated metadata or signatures

These add no value and clutter the commit history.

# Commit with generated message (NO extra metadata)
git commit -m "$(cat <<'EOF'
<generated_message>
EOF
)"

# Show result
git log -1 --oneline

Decision Flow

START
  |
  v
Do we have conversation context about changes?
  |
  +-- YES --> Use context to generate message
  |            (Skip git diff)
  |
  +-- NO --> Run git diff to analyze changes
              |
              v
            Are changes staged?
              |
              +-- YES --> git diff --cached
              |
              +-- NO --> git diff (working directory)
  |
  v
Generate concise commit message
  |
  v
Present to user for confirmation
  |
  v
User confirms?
  |
  +-- YES --> git commit
  |
  +-- NO --> Exit (no commit)
  |
  v
END

Examples

Example 1: With Context (No Git Diff)

Conversation:

User: Add health check commands to es_tool.sh
Assistant: [edits es_tool.sh, adds check-health, check-shards, etc.]
User: Create a commit

Skill execution:

1. Context available: Edited es_tool.sh, added health check commands
2. Skip git diff
3. Generate:

   feat: add cluster health check commands
   
   Implements check-health, check-shards, explain-allocation,
   and fix-red-shards for ES cluster diagnostics.
   

Example 2: No Context (Use Git Diff)

Conversation:

User: Generate commit message

Skill execution:

1. No context available
2. Run git diff --cached:

   diff --git a/script/es_tool.sh b/script/es_tool.sh
   @@ -841,7 +841,7 @@ execute_http_request() {
   -            content_type="text/plain"
   +            content_type="application/x-ndjson"
   +            # Ensure body ends with newline
   +            if [[ "$body" != *$'\n' ]]; then
   +                body="${body}"$'\n'
   +            fi
   

3. Analyze: Changed content-type for bulk requests, added newline
4. Generate:

   fix: correct bulk request content-type
   
   Use application/x-ndjson and ensure trailing newline
   for ES bulk API NDJSON format compliance.
   

Example 3: User Provides Context

Conversation:

User: Commit the fix for the bulk API newline issue

Skill execution:

1. Context from user: "fix for bulk API newline issue"
2. Quick check: git diff --cached --name-only (just filenames)

   script/es_tool.sh
   

3. Generate (minimal diff needed):

   fix: ensure bulk requests end with newline
   
   Add trailing newline to bulk request body for
   ES NDJSON format requirements.
   

Best Practices

DO:

• Use conversation context when available
• Run git diff when context is missing
• Keep summary under 50 characters
• Use imperative mood (add, fix, update)
• Focus on WHAT and WHY
• Confirm with user before committing

DON'T:

• Skip git diff when you have no context
• Write verbose explanations
• Describe HOW code was implemented
• Auto-commit without confirmation
• Use past tense (added, fixed, updated)

Git Tags

When user requests creating a tag (for CI/CD pipeline trigger, release, etc.):

1. Check existing tag format first:

   git tag --sort=-creatordate | head -5
   

2. Keep format consistent - DO NOT add 'v' prefix unless project already uses it:

   • If existing: 0.4.0, 0.3.0 → use 0.4.1 (no 'v')
   • If existing: v0.4.0, v0.3.0 → use v0.4.1 (with 'v')

3. Never assume tag format - always verify from existing tags

Notes

• Optimizes for speed by using context when available
• Falls back to git diff when needed for accuracy
• Generates concise but informative messages
• Always confirms before committing
• Works in both interactive and standalone scenarios