update-changelog

name	update-changelog
description	Auto-update the project changelog from git history. Analyzes commits, categorizes changes, and writes human-readable monthly changelog files.
argument-hint	[month: YYYY-MM or 'current']

Update Changelog

Generate or update monthly changelog files in changelog/ from git commit history.

Arguments

• No argument or current: update the current month's changelog
• YYYY-MM (e.g. 2026-03): update a specific month
• all: regenerate all months with commits

Changelog Location

• Directory: $CWD/changelog/
• File format: YYYY-MM.md (one file per month)
• Example: changelog/2026-03.md

Process

Step 1: Determine Target Month(s)

# Get the argument
MONTH_ARG="$1"  # e.g. "2026-03", "current", "all", or empty

# If empty or "current", use current month
# If "all", get all months with commits:
git log --format="%ad" --date=format:"%Y-%m" | sort -u

Step 2: Get Commits for Target Month

For each target month (YYYY-MM):

# Get commits with stats
git log --since="YYYY-MM-01" --until="YYYY-MM+1-01" \
  --pretty=format:"%h|%ad|%s" --date=short --stat

Step 3: Analyze and Categorize

Group changes by date, then categorize each commit:

Category	When to use
Added	New files, features, skills, agents, scripts
Changed	Modified existing files, updates, refactors
Removed	Deleted files, removed features
Renamed	Moved or renamed files/skills
Fixed	Bug fixes

Tips for good changelog entries:

• Lead with the what (bold the name), then explain briefly
• Use git diff --stat to understand scope of changes
• Group related commits into a single entry when they're part of the same change
• Mention file counts or line changes for major modifications
• Skip noise commits (typo fixes, .DS_Store, etc.) or fold them into parent entries

Step 4: Write Changelog

Write/update the file at changelog/YYYY-MM.md:

# Changelog - Month Year

## YYYY-MM-DD

### Added
- **thing-name** - Brief description

### Changed
- **thing-name** - What changed and why

### Removed
- **thing-name** - Why removed or what replaced it

Rules:

• Dates in descending order (newest first)
• One ## section per day that has commits
• Only include ### categories that have entries
• Bold the primary subject of each entry
• Keep entries concise (1 line each)
• Don't include empty categories

Step 5: Confirm

Show the user what was written/updated. Do NOT commit - let the user review.