feat: conventional commits (cometbft#1995)

Check PR title follows the Conventional Commits spec.

---

#### PR checklist

- [ ] ~~Tests written/updated~~
- [ ] ~~Changelog entry added in `.changelog` (we use
[unclog](https://github.com/informalsystems/unclog) to manage our
changelog)~~
- [x] Updated relevant documentation (`docs/` or `spec/`) and code
comments

.github/PULL_REQUEST_TEMPLATE.md

@@ -28,4 +28,4 @@ https://github.com/orgs/cometbft/projects/1
 - [ ] Tests written/updated
 - [ ] Changelog entry added in `.changelog` (we use [unclog](https://github.com/informalsystems/unclog) to manage our changelog)
 - [ ] Updated relevant documentation (`docs/` or `spec/`) and code comments
-
+- [ ] Title follows the [Conventional Commits](https://www.conventionalcommits.org/en/v1.0.0/) spec

.github/workflows/conventional-pr-title.yml

@@ -0,0 +1,51 @@
+name: "Conventional PR Title"
+
+on:
+ pull_request_target:
+ types:
+ - opened
+ - edited
+ - synchronize
+
+permissions:
+ pull-requests: read
+
+jobs:
+ main:
+ name: Validate PR title
+ runs-on: ubuntu-latest
+ steps:
+ - uses: amannn/action-semantic-pull-request@v5
+ id: lint_pr_title
+ env:
+ GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+
+ - uses: marocchino/sticky-pull-request-comment@v2
+ # When the previous steps fails, the workflow would stop. By adding this
+ # condition you can continue the execution with the populated error message.
+ if: always() && (steps.lint_pr_title.outputs.error_message != null)
+ with:
+ header: pr-title-lint-error
+ message: |
+ Hey there and thank you for opening this pull request! 👋🏼
+
+ We require pull request titles to follow the [Conventional Commits specification](https://www.conventionalcommits.org/en/v1.0.0/) and it looks like your proposed title needs to be adjusted.
+
+ Details:
+
+ ```
+ ${{ steps.lint_pr_title.outputs.error_message }}
+ ```
+
+ General format: `type(scope): msg`
+ Breaking change: `type(scope)!: msg`
+ Multi-scope change: `type: msg`
+ Types: `feat`, `fix`, `build`, `chore`, `ci`, `docs`, `refactor`, `perf`, `test`, `revert`.
+ Example: `fix(cmd/cometbft/commands/debug): execute p.Signal only when p is not nil`
+
+ # Delete a previous comment when the issue has been resolved
+ - if: ${{ steps.lint_pr_title.outputs.error_message == null }}
+ uses: marocchino/sticky-pull-request-comment@v2
+ with:
+ header: pr-title-lint-error
+ delete: true

CONTRIBUTING.md

@@ -501,18 +501,24 @@ Before merging a pull request:
 
 ### Git Commit Style
 
-We follow the [Go style guide on commit messages][go-git-commit-style]. Write
-concise commits that start with the package name and have a description that
-finishes the sentence "This change modifies CometBFT to...". For example,
+We follow the [Conventional Commits][conventional-commits] spec. Write concise
+commits that start with a type (`fix`, `feat`, `chore`, `ci`, `docs`, etc.) and
+an optional scope - package name (e.g., `feat(internal/consensus)`), followed
+by a description that finishes the sentence "This change modifies CometBFT
+to...".
+
+If the commit introduces a breaking change, append the `!` after the scope
+(e.g., `feat(internal/consensus)!`).
+
+For example,
 
 ```sh
-cmd/debug: execute p.Signal only when p is not nil
+fix(cmd/cometbft/commands/debug): execute p.Signal only when p is not nil
 
 [potentially longer description in the body]
 
 Fixes #nnnn
 ```
-
 Each PR should have one commit once it lands on `main`; this can be accomplished
 by using the "squash and merge" button on GitHub. Be sure to edit your commit
 message, though!
@@ -576,8 +582,8 @@ in the [OpenAPI file](./rpc/openapi/openapi.yaml)**.
 [`clang-format`]: https://clang.llvm.org/docs/ClangFormat.html
 [unclog]: https://github.com/informalsystems/unclog
 [git-squash]: https://stackoverflow.com/questions/5189560/squash-my-last-x-commits-together-using-git
-[go-git-commit-style]: https://tip.golang.org/doc/contribute.html#commit_messages
 [go-testing]: https://golang.org/pkg/testing/
 [Fuzz tests]: https://en.wikipedia.org/wiki/Fuzzing
 [delve]: https://github.com/go-delve/delve
 [log-lazy]: https://github.com/cometbft/cometbft/blob/main/libs/log/lazy.go
+[conventional-commits]: https://www.conventionalcommits.org/en/v1.0.0/