---
source_keys:
  - conventional-commits-spec
  - commitlint-config-conventional
---

# Conventional Commits Specification (v1.0.0)

Conventional Commits is a lightweight convention on top of commit messages that provides a set of rules for creating an explicit commit history. It enables automated tooling (CHANGELOG generation, semantic version bumping) and structured filtering.

## Message Format

```text
<type>[optional scope]: <description>

[optional body]

[optional footer(s)]
```

Each section is separated by a blank line. The header is the only required part.

## Rules

| Element | Rule |
|---|---|
| `type` | Required. Lowercase noun. |
| `scope` | Optional. Noun in parentheses directly after type: `feat(api):`. |
| `description` | Required. Immediately follows `type/scope: `. Imperative mood, no trailing period. |
| `body` | Optional. Begins one blank line after description. Free-form prose, multiple paragraphs allowed. Lines max 100 characters. |
| `footer(s)` | Optional. Begins one blank line after body (or description). `<token>: <value>` format. Lines max 100 characters. |
| `BREAKING CHANGE` | Must be uppercase. Either a footer token or signalled by `!` before the colon. |

## Standard Types

The spec itself mandates only `feat` and `fix`. The 11-type set below is the de-facto standard from `@commitlint/config-conventional` (Angular commit message guidelines), not a spec requirement — but it is what this skill validates against.

### 11-type set (commitlint/config-conventional)

| Type | Meaning | SemVer impact | Appears in CHANGELOG |
|---|---|---|---|
| `feat` | New user-visible feature | MINOR | Yes |
| `fix` | Bug fix | PATCH | Yes |
| `perf` | Performance improvement, no API change | PATCH | Yes |
| `revert` | Reverts a previous commit | PATCH | Yes |
| `docs` | Documentation only | none | No |
| `style` | Formatting, whitespace — no logic change | none | No |
| `refactor` | Code restructuring — no feature or fix | none | No |
| `test` | Adding or fixing tests | none | No |
| `build` | Build system or external dependency changes | none | No |
| `ci` | CI configuration and scripts | none | No |
| `chore` | Anything not fitting above | none | No |

A `BREAKING CHANGE` footer or `!` on **any** type always triggers a MAJOR bump.

## Breaking Changes

Two equivalent notations:

**`!` in header** (preferred — visible in `git log --oneline`):
```text
feat!: drop support for Node 6
feat(api)!: remove deprecated endpoint
```

**`BREAKING CHANGE` footer** (machine-readable body):
```text
feat: allow config to extend other configs

BREAKING CHANGE: `extends` key now used for extending config files
```

**Both together** (most explicit):
```text
feat!: drop support for Node 6

BREAKING CHANGE: use JavaScript features not available in Node 6.
```

Rules:
- `BREAKING CHANGE` must be all caps.
- `BREAKING-CHANGE` (hyphenated) is an accepted synonym.
- Any type can carry a breaking change, not just `feat`.
- The footer value must describe what broke.

## Footer Token Rules

```text
<token>: <value>
<token> #<value>    # for issue references
```

- Tokens use hyphens for word separation: `Reviewed-by`, `Co-authored-by`, `Refs`.
- Exception: `BREAKING CHANGE` (space allowed, uppercase).
- Multiple footers allowed, one per line.
- Blank line required before the footer block.

Valid footer examples:
```text
Reviewed-by: Z
Refs: #123
Co-authored-by: Alice <alice@example.com>
BREAKING CHANGE: the `--format` flag now requires a value
```

## Examples

Minimal — no body, no footer:
```text
docs: correct spelling of CHANGELOG
```

With scope:
```text
feat(lang): add Polish language
```

Breaking change via `!`:
```text
feat!: send an email to the customer when a product is shipped
```

Breaking change via footer:
```text
feat: allow provided config object to extend other configs

BREAKING CHANGE: `extends` key in config file is now used for extending other config files
```

Multi-paragraph body with multiple footers:
```text
fix: prevent racing of requests

Introduce a request id and a reference to latest request. Dismiss
incoming responses other than from latest request.

Remove timeouts which were used to mitigate the racing issue but are
obsolete now.

Reviewed-by: Z
Refs: #123
```

Revert:
```text
revert: let us never again speak of the noodle incident

Refs: 676104e, a215868
```

## commitlint Constraints (config-conventional)

| Constraint | Value |
|---|---|
| Header max length | 100 characters |
| Subject must not end with `.` | enforced |
| Subject must be lowercase (not sentence-case or UPPER-CASE) | enforced |
| Body / footer line max length | 100 characters |
| Type must be one of the 11 standard types | error if not |
| Blank line before body | warning |
| Blank line before footer | warning |

## SemVer Mapping Summary

| Condition | SemVer bump |
|---|---|
| `fix`, `perf`, `revert` | PATCH |
| `feat` | MINOR |
| Any type with `BREAKING CHANGE` or `!` | MAJOR |
| All other types (`docs`, `style`, `refactor`, `test`, `build`, `ci`, `chore`) | none |