Version Bumper — semantic version from Conventional Commits

Load this skill when you need to compute the next semantic version and a suggested release tag from the commit history of a git repository that follows Conventional Commits. It is the release-pipeline counterpart of commit-message-writer (writes the commits) and changelog-generator (renders the changelog): this skill decides what version number the changelog and the release tag should carry.

The tool is read-only and offline: it never creates tags, never writes files, and makes no network calls. It reads git log subjects, classifies each commit by type, and prints the current version, the next version and a suggested tag. For testability the commit list can be fed from the COMMITS environment variable or a file (--commits FILE, one subject per line) — no git repository required.

The bumper script

scripts/bumper.py — pure Python 3 stdlib (no dependencies).

Bump rules (Conventional Commits v1.0.0)

Type matching is case-insensitive (Feat: counts as feat). Unknown types are counted as other and never trigger a bump.

Output

latest_tag: v1.0.0
current_version: 1.0.0
next_version: 1.5.0
suggested_tag: v1.5.0
bump: minor
commits_analyzed: 14
counts: feat=1, fix=8, perf=2, refactor=1, docs=1, style=1, test=2, chore=1, build=0, ci=0, revert=0, breaking=1, other=0

Flags

• --current X.Y.Z — baseline version; skips tag lookup
• --from-tags — take the baseline from the highest semver tag (v1.2.3, 1.2.3); falls back to 0.0.0 with a warning when no tags exist
• --commits FILE — read commit subjects from a file (one per line) instead of git log; useful for tests and for repos without git
• --dry-run — accepted for pipeline compatibility; the tool is read-only, so this is the default behavior
• -s / --stable — deterministic output: sorts the analyzed commits and guarantees the same next_version for the same input

Usage example (typical)

# Before a release: what version should the next tag carry?
python3 skills/version-bumper/scripts/bumper.py --path . --from-tags

# Pin the baseline explicitly (no tag lookup)
python3 skills/version-bumper/scripts/bumper.py --path . --current 1.2.3

# Deterministic output for CI / release pipeline
python3 skills/version-bumper/scripts/bumper.py --path . --from-tags -s

# Test the classifier without a git repo
python3 skills/version-bumper/scripts/bumper.py --commits commits.txt --current 1.2.3

Interpretation guidance

• bump: major — at least one breaking commit (! or BREAKING CHANGE: footer). Review the breaking changes before tagging; MAJOR signals a compatibility break to consumers.
• bump: minor — new features present, no breaking changes.
• bump: patch — only fixes/refactors/perf; no features.
• bump: none — only docs/chore/style/test/build/ci/revert commits. Do not create a release tag; the version stays unchanged.
• latest_tag: none — no semver tags found; the tool started from 0.0.0. For a first release, decide whether v0.1.0 (first feature) or v1.0.0 (first stable API) is appropriate.
• The tool only suggests a tag. Creating the tag, updating the changelog and pushing are separate steps — run changelog-generator with the suggested version, then tag manually.

Do NOT use

• Do NOT use when the repository does not follow Conventional Commits — the classification will be mostly other and the suggestion meaningless.
• Do NOT use to create tags or modify the repository — the tool is read-only by design.
• Do NOT use for pre-release/build-metadata schemes (1.2.3-rc.1, 1.2.3+build.5) — the parser accepts only plain X.Y.Z / vX.Y.Z.
• Do NOT use to rewrite history or reorder commits — the tool only reads.

Canonical analogues

Full source depth — in references/canonical-patterns.md. Backbone:

Installation

# For opencode
cp -r skills/version-bumper ~/.config/opencode/skills/

# For other agents
# Copy the skill folder to your skills directory; requires Python 3.
# git is optional — --commits FILE mode works without it.

Note: the tool suggests a version; it never tags, never commits and never pushes. Wire it into the release pipeline as the version source for changelog-generator, then create the tag yourself.

Boundaries

• Do not use to create tags or publish a release; it only recommends a version.

Evidence and completion gate

Run the documented command against the user’s actual input. Report the command, exit status, files changed or produced, and relevant stdout/stderr. Separate blocked or pre-existing failures from failures introduced by the current work. Do not call the result complete when the script was only described or when an artifact was not reopened and checked.