ADD Changelog Command v0.5.0

ADD Changelog Command v0.5.0

Generate or refresh the project's CHANGELOG.md from git history using conventional commit parsing. Follows the Keep a Changelog format.

Pre-Flight Check

1. Check if CHANGELOG.md exists in the project root
2. If it does NOT exist, create it from ${CLAUDE_PLUGIN_ROOT}/templates/changelog.md.template
3. Read .add/config.json for changelog.lastProcessedCommit (may be null)
4. Determine mode: --from-scratch flag means full regeneration; otherwise incremental

Conventional Commit Mapping

Map conventional commit prefixes to Keep a Changelog sections:

Commit Prefix	Changelog Section
feat:	Added
fix:	Fixed
docs:	Documentation
refactor:	Changed
perf:	Changed
deprecate:	Deprecated
remove:	Removed
security:	Security
revert:	Fixed

Excluded Prefixes (not added to changelog)

These are internal/maintenance commits and should be silently skipped:

• chore:
• test:
• ci:
• style:
• build:

Non-Conventional Commits

Commits that do not match any conventional prefix are categorized under Changed with the full message as the entry text.

Merge Commits

Skip merge commits entirely — they duplicate the content of the merged commits.

Phase 1: Gather Commits

Incremental Mode (default)

1. Read CHANGELOG.md to understand current state
2. Read .add/config.json for changelog.lastProcessedCommit
3. If lastProcessedCommit is set:
   • Run git log --oneline --no-merges {lastProcessedCommit}..HEAD to get new commits
4. If lastProcessedCommit is null:
   • Run git log --oneline --no-merges to get all commits
5. If no new commits found, report "Changelog is up to date" and exit

From-Scratch Mode (--from-scratch)

1. Run git tag --sort=-version:refname to get all version tags
2. Run git log --oneline --no-merges to get full commit history
3. Group commits by version tags:
   • Commits after the latest tag go in [Unreleased]
   • Commits between tags go in [tag] - date sections (use tag date)
   • Commits before the earliest tag go in the earliest version section
4. Regenerate CHANGELOG.md entirely (preserve the header from template)

Phase 2: Parse Commits

For each commit message:

1. Extract prefix: Match against ^(feat|fix|docs|refactor|perf|deprecate|remove|security|revert|chore|test|ci|style|build)(\(.+\))?!?:\s*(.+)$
2. Check exclusion list: If prefix is chore, test, ci, style, or build, skip this commit
3. Strip prefix: Remove the prefix and scope from the message, keeping only the description
4. Sentence-case: Capitalize the first letter of the description
5. Detect spec cross-references: Look for (#spec-slug) pattern in the message — preserve these as-is
6. Detect breaking changes: If ! is present after the scope (e.g., feat!:) or commit body contains BREAKING CHANGE:, prefix the entry with **BREAKING:**
7. Truncate long entries: If the subject line exceeds 100 characters, truncate to 100 chars with "..."
8. Map to section: Use the mapping table above to determine which changelog section

Entry Format

- {Sentence-cased description} [(#spec-slug)]

Examples:

• feat: add OAuth2 login flow (#auth-oauth) becomes - Add OAuth2 login flow (#auth-oauth) under Added
• fix: correct redirect URL becomes - Correct redirect URL under Fixed
• feat!: redesign API response format becomes - **BREAKING:** Redesign API response format under Added

Phase 3: Deduplicate

Before adding any entry to the changelog:

1. Read the current CHANGELOG.md content
2. For each parsed entry, check if an entry with the same text already exists in ANY section of [Unreleased]
3. If a duplicate is found, skip that entry
4. Only add genuinely new entries

Phase 4: Write Changelog

Section Ordering

Within [Unreleased] (and each versioned section), order subsections as:

1. Added
2. Changed
3. Deprecated
4. Removed
5. Fixed
6. Security
7. Documentation

Only include subsections that have entries — do not write empty subsections.

Writing Strategy

1. Read existing CHANGELOG.md
2. Find the ## [Unreleased] line
3. Parse any existing entries under [Unreleased] to merge with new entries
4. Group all entries (existing + new) by section
5. Write the updated [Unreleased] block
6. Preserve all versioned sections below [Unreleased] unchanged

Update Config

After writing, update .add/config.json:

• Set changelog.lastProcessedCommit to the current HEAD commit hash (run git rev-parse HEAD)

Phase 5: Report

Display a summary of what was added:

Changelog updated.

NEW ENTRIES:
  Added: {N} entries
  Changed: {N} entries
  Fixed: {N} entries
  {other sections as applicable}

SKIPPED:
  Excluded (chore/test/ci/style/build): {N} commits
  Duplicates: {N} entries already present
  Merge commits: {N} skipped

Total: {N} new entries added to [Unreleased]
Last processed commit: {short hash}

Edge Cases

Case	Behavior
No conventional prefix	Categorize under "Changed" with full message
Empty push (no new commits)	Exit early with "Changelog is up to date"
CHANGELOG.md missing	Create from template, then proceed
.add/config.json missing	Process all commits (no lastProcessedCommit)
Scoped commits (e.g., feat(auth):)	Strip scope along with prefix
Multiple spec references	Preserve all (#slug) references
Very long subject (>100 chars)	Truncate to 100 chars with "..."