feat: Add Conventional Commits linter for CI

.github/workflows/commit-linter.yaml

@@ -0,0 +1,38 @@
+name: commit-linter
+
+on:
+  pull_request:
+  push:
+    branches: [main]
+
+jobs:
+  commit-lint:
+    runs-on: ubuntu-22.04
+    steps:
+      - uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
+
+      - uses: cachix/install-nix-action@v25
+        with:
+          nix_path: nixpkgs=channel:nixos-unstable
+
+      - uses: DeterminateSystems/magic-nix-cache-action@main
+
+      - name: npm install
+        run: nix develop --command npm install --include=dev
+
+      - name: Print versions
+        run: |
+          git --version
+          node --version
+          npm --version
+          npx commitlint --version
+
+      - name: Validate current commit (last commit) with commitlint
+        if: github.event_name == 'push'
+        run: nix develop --command npx commitlint --last --verbose
+
+      - name: Validate PR commits with commitlint
+        if: github.event_name == 'pull_request'
+        run: nix develop --command npx commitlint --from ${{ github.event.pull_request.head.sha }}~${{ github.event.pull_request.commits }} --to ${{ github.event.pull_request.head.sha }} --verbose

.gitignore

@@ -16,7 +16,6 @@ pom.xml.asc
 /.lsp/.cache/
 /node_modules/
 /out/
-package-lock.json
 /cljs-test-runner-out/
 /.direnv/
 /.shadow-cljs/

README.md

@@ -131,6 +131,21 @@ though this should only need to happen the first time you run it.
 You will see the changes to `deps.edn` reflected in `deps-lock.json`; you should commit these; and the
 release build will work again.
 
+#### Style
+
+##### Git
+
+This repo follows the [Conventional Commits](https://www.conventionalcommits.org/en/v1.0.0/#summary) 
+specification for commit messages. We use the defaults, except our subject lines 
+are in sentence case (e.g., "This is in sentence case") and do not end in a 
+stop/period.
+
+To check your most recent commit message, run `npx commitlint --from HEAD~1 
+--to HEAD --verbose`. If you need to change the last message, run `git commit 
+--amend`.
+
+If you forget, a CI job will check it for you when you make a pull request.
+
 #### Building a jar (portable Java application)
 
 ```shell

commitlint.config.mjs

@@ -0,0 +1,6 @@
+export default { 
+    extends: ['@commitlint/config-conventional'],
+    rules: {
+        'subject-case': [2, 'always', 'sentence-case'] // override default
+    }
+};

flake.nix

@@ -54,7 +54,7 @@
       in {
         # development shell
         devShells.default = pkgs.mkShell {
-          buildInputs = [ pkgs.openjdk21 pkgs.clojure pkgs.babashka depsCache ] ++ (basicToolsFn pkgs);
+          buildInputs = [ pkgs.openjdk21 pkgs.clojure pkgs.babashka pkgs.nodejs_20 depsCache ] ++ (basicToolsFn pkgs);
 
           shellHook = ''
             echo "Setting up default dev shell..."