ci: enforce commitlint only on PR titles and descriptions

.github/workflows/pr.yml

@@ -17,17 +17,6 @@ jobs:
           fetch-depth: 0
       - uses: editorconfig-checker/action-editorconfig-checker@v2
       - run: editorconfig-checker
-  commitlint:
-    name: Lint commits for semantic-release
-    runs-on: ubuntu-latest
-    steps:
-      - uses: actions/checkout@v6
-        with:
-          fetch-depth: 0
-      - uses: actions/setup-node@v6
-        with:
-          node-version: "20"
-      - run: npx commitlint --from=${{ github.event.pull_request.base.sha }} --to=${{ github.sha }} --verbose
   security:
     name: Security validation
     runs-on: ubuntu-latest

.github/workflows/pr_title.yaml

@@ -0,0 +1,63 @@
+name: PR Title Check
+
+on:
+  pull_request_target:
+    types: [opened, edited, synchronize, reopened]
+jobs:
+  commitlint:
+    name: PR title / description conforms to semantic-release
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/setup-node@v6
+        with:
+          node-version: "20"
+      - run: npm install @commitlint/config-conventional
+      - run: >
+          echo 'module.exports = {
+            // Workaround for https://github.com/dependabot/dependabot-core/issues/5923
+            "ignores": [(message) => /^Bumps \[.+]\(.+\) from .+ to .+\.$/m.test(message)],
+            "rules": {
+              "body-max-line-length": [0, "always", Infinity],
+              "footer-max-line-length": [0, "always", Infinity],
+              "body-leading-blank": [0, "always"]
+            }
+          }' > .commitlintrc.js
+      - run: npx commitlint --extends @commitlint/config-conventional --verbose <<< $COMMIT_MSG
+        env:
+          COMMIT_MSG: >
+            ${{ github.event.pull_request.title }}
+
+            ${{ github.event.pull_request.body }}
+      - if: failure()
+        uses: actions/github-script@v8
+        with:
+          script: |
+            const message = `**ACTION NEEDED**
+
+              Substrait follows the [Conventional Commits
+              specification](https://www.conventionalcommits.org/en/v1.0.0/) for
+              release automation.
+
+              The PR title and description are used as the merge commit message.\
+              Please update your PR title and description to match the specification.
+              `
+            // Get list of current comments
+            const comments = await github.paginate(github.rest.issues.listComments, {
+              owner: context.repo.owner,
+              repo: context.repo.repo,
+              issue_number: context.issue.number
+            });
+            // Check if this job already commented
+            for (const comment of comments) {
+              if (comment.body === message) {
+                return // Already commented
+              }
+            }
+            // Post the comment about Conventional Commits
+            github.rest.issues.createComment({
+              owner: context.repo.owner,
+              repo: context.repo.repo,
+              issue_number: context.issue.number,
+              body: message
+            })
+            core.setFailed(message)