ci: add new feature notifier (#2889)

feat(ci): add new feature notifier

Signed-off-by: Janek Nouvertné <[email protected]>

---------

Signed-off-by: Janek Nouvertné <[email protected]>
Co-authored-by: Janek Nouvertné <[email protected]>

.github/workflows/pr-target.yml

@@ -6,19 +6,35 @@ on:
       - opened
       - edited
       - synchronize
-    branches:
-      - main
 
 permissions:
-  pull-requests: read
+  pull-requests: write
 
 jobs:
   main:
     name: Validate PR target branch
     runs-on: ubuntu-latest
     steps:
       - name: Check PR target
-        if: ${{ startsWith(github.event.pull_request.title, 'feat') }}
+        id: check-pr-target
+        uses: actions/github-script@v7
+        with:
+          script: |
+            const isFeature = context.payload.pull_request.title.startsWith('feat');
+            const targetsMain = context.payload.pull_request.base.ref == 'main';
+            core.setOutput('needs-rebase', isFeature && targetsMain ? 'true' : 'false');
+
+      - name: Comment PR
+        if: steps.check-pr-target.outputs.needs-rebase == 'true'
+        uses: thollander/actions-comment-pull-request@v2
+        with:
+          message: "It looks like you are adding a new feature! :rocket: Please rebase and point your PR to the `develop` branch."
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+          comment_tag: check_pr_target
+          mode: recreate
+
+      - name: Fail if feature PR is targeted to main
+        if: steps.check-pr-target.outputs.needs-rebase == 'true'
         uses: actions/github-script@v7
         with:
           script: |