AI-Driven Changelog

Set up a changelog system AI agents maintain during development. Two shapes, chosen by project type:

• Software projects: agents write entries under ## [Unreleased]; automation stamps version numbers at release time (CalVer or SemVer). No agent ever writes version numbers; the build process handles that.
• Non-code projects (no build system): agents add terse bullets under a date heading (## YYYY-MM-DD) by hand. No script, no version numbers. See references/dated.md.

Setup workflow

1. Detect the build system: Check for Makefile, Justfile, package.json, Cargo.toml, pyproject.toml, go.mod. Note which config files contain a "version" field.

2. Check whether this is a software project at all. If there's no build system from step 1 and no version convention (a docs repo, writing or notes vault, content site, research or config collection), use Dated mode: date-based changelog headings, no version script, no build integration. Skip straight to references/dated.md and ignore the script/build steps below. Otherwise, detect the versioning scheme by inspecting (highest confidence first):

   • CHANGELOG.md heading style: ## [YYYY.M.N] headings → CalVer; ## [X.Y.Z] headings or prose mentioning "SemVer" → SemVer
   • Git tags from git tag --list | head: vX.Y.Z → SemVer; YYYY.M.N → CalVer
   • VERSION file with content matching ^[0-9]+\.[0-9]+\.[0-9]+ → SemVer
   • Manifest version field (package.json, Cargo.toml, pyproject.toml) matching X.Y.Z → SemVer

   If signals are absent or contradictory, ask the user. Suggest SemVer for projects with established version history (existing tags, manifest versions, prior changelog entries) and CalVer for greenfield projects where automatic versioning is preferable. Each scheme has trade-offs documented in its reference file.

3. Read the scheme reference that matches the chosen scheme. It contains the build integration recipes, CLAUDE.md snippet, GitHub Actions pattern, and scheme-specific gotchas:

   • CalVer → references/calver.md
   • SemVer → references/semver.md
   • Dated (non-code projects) → references/dated.md

4. Ask the user about optional features (CalVer/SemVer only; skip for Dated mode):

   • Pinned ## Known Bugs section above ## [Unreleased]? (default: yes)
   • GitHub Actions release workflow integration? (default: skip unless asked)

5. Generate or update CHANGELOG.md. For CalVer/SemVer use references/changelog-template.md; for Dated use the template in references/dated.md. If a CHANGELOG.md already exists, do NOT overwrite it; insert the HTML comment and the appropriate structure (## [Unreleased] for CalVer/SemVer, today's date heading for Dated) above existing entries.

6. Copy scripts/version.py from this skill into the target project's scripts/ directory. Make it executable (chmod +x). Skip in Dated mode - there is no script.

7. Apply the scheme reference: follow the build-integration recipe from the chosen reference file. Add targets to the existing build system, or create a minimal Makefile if none exists. Skip in Dated mode - there is no build integration.

8. Update CLAUDE.md with the snippet from the chosen scheme reference. Insert into the project's development workflow section, or create one. In Dated mode this is the only mechanism that keeps the changelog current, so make sure the snippet lands. Add "Squash changes within the same day/version (do not add changes to changes)." Keep the snippet's what-to-log and entry-length rules intact - they are what stops agents logging trivia and writing paragraphs for simple changes.

9. Verify:

   • CalVer: uv run scripts/version.py version should print today's CalVer; then uv run scripts/version.py stamp --dry-run previews the stamp
   • SemVer: uv run scripts/version.py stamp --version <current-version> --dry-run --changelog-only previews the stamp without touching the canonical version source
   • Dated: confirm CHANGELOG.md has today's date heading and the CLAUDE.md snippet is in place; nothing to run

Project detection

Indicator, then what to stamp and how to integrate:

• Makefile - stamp whatever config files the project has; add make targets
• Justfile - same config files; add just recipes
• package.json - stamp package.json; add npm scripts, or a Makefile
• Cargo.toml - stamp Cargo.toml; Makefile wrapper
• pyproject.toml - stamp pyproject.toml; Makefile wrapper
• go.mod - stamp VERSION if present, otherwise nothing; Makefile wrapper
• VERSION file - stamp VERSION; Makefile wrapper
• No build system, code project - nothing to stamp; create a minimal Makefile
• No build system, non-code project - Dated mode: no script, no Makefile

How the script works

scripts/version.py subcommands:

• version: prints today's CalVer to stdout (CalVer projects only)
• stamp: replaces ## [Unreleased] with ## [VERSION] - DATE, re-inserts a fresh ## [Unreleased], and stamps version into auto-discovered config files (package.json, Cargo.toml, pyproject.toml, tauri.conf.json, VERSION)

Flags: --version X.Y.Z (required for SemVer; optional override for CalVer), --dry-run, --changelog-only, --no-changelog.

The script is scheme-agnostic. With no --version, it auto-computes CalVer; with --version, it stamps whatever string you give it. Validation lives in the build system, so SemVer recipes always pass --version and reject malformed input before invoking the script. See references/semver.md for why this split matters.

Run via uv run scripts/version.py stamp or python3 scripts/version.py stamp (no external dependencies).

Gotchas

• Never overwrite existing changelog history. If a CHANGELOG.md exists with content, merge the [Unreleased] structure into it rather than replacing the file.
• Empty Unreleased section: stamping is a no-op if [Unreleased] has no content. This prevents empty version entries.
• fetch-depth: 0 in CI for CalVer: CalVer uses git rev-list --count HEAD. Shallow clones produce wrong commit counts.
• A changelog is not a commit log. Two rules keep it useful, and both must appear in the HTML comment and the CLAUDE.md snippet: log only reader-visible changes (git history covers the rest), and keep entries to one line unless the change is genuinely complex. Without them agents log formatting tweaks and write paragraphs for one-line fixes.
• The HTML comment is the agent's instruction source. The <!-- AI agents: ... --> comment in CHANGELOG.md tells future agents how to write entries. Don't omit it.
• Known Bugs stays pinned. The stamp script preserves ## Known Bugs above ## [Unreleased]. If you add it, agents should maintain it there.
• SemVer + auto-CalVer = silent footgun. If a Makefile in a SemVer project calls python3 scripts/version.py stamp without --version, the script auto-computes CalVer and writes that into the changelog. The recipes in references/semver.md always pass --version; preserve that contract in any custom integration.
• Config file stamping is first-match-only for TOML. The regex replaces only the first version = "..." line, which is the package version. Dependency versions are unaffected.
• VERSION file stamping requires existing semver-shaped content. The script's VERSION handler only rewrites the file if its current content matches ^\d+\.\d+\.\d+. Build numbers, tag-prefixed versions, or other formats are left alone.