changelog-generator

changelog-generator is a skill for Claude Code, Codex from tmj-90/gaffer. It costs 68 tokens per session (956 once invoked), scanned A, original, Apache-2.0.

A release-note tool that turns Conventional Commits—structured commit messages—into version changes and a CHANGELOG.md file.

In plain words
What is it for?
It helps calculate the next semantic version, group changes into Keep a Changelog sections, and automate release notes in continuous integration.
Why use it?
It removes the guesswork from deciding whether a release needs a major, minor, or patch version increase and keeps notes consistent.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one.

Needs its repository: it runs a file that does not travel with it, so clone the repository first. The line is | python scripts/generate_changelog.py \.

Good fit It helps calculate the next semantic version, group changes into Keep a Changelog sections, and automate release notes in continuous integration.

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Install

Getting it into your agent

It runs from inside its repository, so the clone comes first — what it calls does not travel with the file alone.

Clone the repo
git clone --depth 1 https://github.com/tmj-90/gaffer
agentmods
npx agentmods add skills/tmj-90/gaffer/changelog-generator

Made for: Claude Code, Codex.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

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README.md
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Your own site
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Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

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Your own site · 80×15
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Per session 68 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 956 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00068 $0.00956
Opus 5 $0.00034 $0.00478
Sonnet 5 $0.00014 $0.00191
Haiku 4.5 $0.00007 $0.00096

Measured 9d ago against content hash e8fb1dd812d8, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-09, from the pricing page.

Security

Grade A, and why

changelog-generator scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 9d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

runner/skills/changelog-generator/SKILL.md · 103 lines

How it starts

The opening of the file, as written. The whole thing — 103 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Generate consistent, auditable release notes

Conventional Commits → semantic bump → Keep a Changelog. Three steps, always in order.

Conventional Commit → Semantic Bump

Commit type Bump
feat: MINOR
fix:, perf: PATCH
BREAKING CHANGE: footer or ! suffix MAJOR
refactor:, docs:, chore:, ci:, test: No version bump

Multiple commits in a release: take the highest-ranking bump. One feat: in a release of ten fix: commits → MINOR bump.

Keep a Changelog sections

## [1.4.0] — 2026-06-28

### Added
- feat commits

### Changed
- refactor commits; BREAKING CHANGE goes here with migration note

### Deprecated
### Removed
### Fixed
- fix commits
### Security
- security commits

Use ISO 8601 dates (YYYY-MM-DD). Link version headers to the git tag diff URL.

Git range commands

# Commits between two tags
git log v1.3.0..v1.4.0 --pretty=format:'%s'

# Commits since last tag to HEAD
git log $(git describe --tags --abbrev=0)..HEAD --pretty=format:'%s'

# With author and hash (for detailed notes)
git log v1.3.0..v1.4.0 --pretty=format:'%h %an %s'

CI integration pattern

# .github/workflows/release.yml (excerpt)
- name: Generate changelog
  run: |
    git log ${{ env.PREV_TAG }}..HEAD --pretty=format:'%s' \
      | python scripts/generate_changelog.py \
          --next-version ${{ env.NEXT_VERSION }} \
          --format markdown >> CHANGELOG.md

Block the pipeline if commit messages don't follow Conventional Commits format — a linting step before changelog generation prevents garbage output.

Commit message linting rules

A valid Conventional Commit: <type>(<optional scope>): <description>

Valid types: feat, fix, docs, style, refactor, perf, test, build, ci, chore, revert.

Reject: commits with no type prefix; commits with WIP: prefix; commits longer than 72 characters in the subject line.

Steps

  1. Get the commit range. Tag-to-tag or last-tag-to-HEAD.
  2. Parse commit messages. Classify each as feat / fix / breaking / no-bump.
  3. Compute semantic bump. Take the maximum across all commits in the range.
  4. Group into Keep a Changelog sections. Added / Changed / Fixed / Security.
  5. Write the changelog entry. Date, version, sections. Link version to git tag diff.
  6. Lint commit messages before finalising — reject any that don't conform.
  7. Verify. Check that the computed version matches the expected bump; confirm the changelog entry renders correctly in Markdown preview.

Read the full file on GitHub · 103 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 9d ago First seen · 103 lines · 68 tokens per session scan A e8fb1dd812d8

Subscribe to this mod's changes

changelog-generator is a skill published in the GitHub repository tmj-90/gaffer (2 stars, last pushed yesterday), licensed Apache-2.0. It adds 68 tokens to every session and 956 once invoked, about $0.0003 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.