ci: add conventional commit enforcement for PR titles

.github/workflows/lint-pr.yaml

@@ -0,0 +1,40 @@
+name: Lint PR
+
+on:
+  pull_request:
+    types:
+      - opened
+      - edited
+      - synchronize
+      - reopened
+      - labeled
+      - unlabeled
+
+jobs:
+  validate-pr-title:
+    name: Validate PR title (Conventional Commits)
+    runs-on: ubuntu-latest
+    permissions:
+      statuses: write
+      pull-requests: read
+    steps:
+      - uses: amannn/action-semantic-pull-request@48f256284bd46cdaab1048c3721360e808335d50 # v6.1.1
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+        with:
+          types: |
+            feat
+            fix
+            docs
+            style
+            refactor
+            test
+            chore
+            ci
+            build
+            perf
+            revert
+          requireScope: false
+          # Allow skipping this check with a label (e.g. for automated/bot PRs)
+          ignoreLabels: |
+            skip-conventional-commit-check

CONTRIBUTING.md

@@ -47,28 +47,29 @@ To set up your development environment for Agentex, please refer to the [README.
 
 ---
 
-## Best Practices for Writing Commit Messages
-
-- **Separate subject from body with a blank line**.
-- **Limit the subject line to 50 characters**.
-- **Capitalize the subject line**.
-- **Do not end the subject line with a period**.
-- **Use the imperative mood in the subject line**  
-  (e.g., “Fix bug” not “Fixed bug” or “Fixes bug”).
-- **Wrap the body at 72 characters**.
-- **Use the body to explain what and why vs. how** (if needed).
-- **Reference relevant issues/PRs** (e.g., `Fixes #123`).
+## Commit and PR Title Guidelines
 
-**Example:**
-```
-Add user authentication middleware
+This project enforces [Conventional Commits](https://www.conventionalcommits.org/en/v1.0.0/) on PR titles. A CI check will validate your PR title before it can be merged.
 
-This middleware intercepts requests to check authentication tokens
-and ensures only valid users can access protected routes.
+**Format:** `type: description` or `type(scope): description`
 
-Fixes #42
+**Allowed types:** `feat`, `fix`, `docs`, `style`, `refactor`, `test`, `chore`, `ci`, `build`, `perf`, `revert`
+
+**Examples:**
+```
+feat: add user authentication middleware
+fix(api): handle empty request body gracefully
+docs: update contributing guidelines
+chore: bump dependency versions
 ```
 
+### General commit message best practices
+
+- **Use the imperative mood** (e.g., “Add feature” not “Added feature”).
+- **Keep the subject line under 72 characters**.
+- **Use the body to explain what and why vs. how** (if needed).
+- **Reference relevant issues/PRs** (e.g., `Fixes #123`).
+
 For more, see: [Chris Beams' guide to writing great commit messages](https://cbea.ms/git-commit/).
 
 ---