Add notice to clear-pr-merge-commit-message (#6019)

source/features/clear-pr-merge-commit-message.tsx

@@ -1,19 +1,32 @@
+import React from 'dom-chef';
 import select from 'select-dom';
 import * as pageDetect from 'github-url-detection';
 
 import features from '../feature-manager';
 import onPrMergePanelOpen from '../github-events/on-pr-merge-panel-open';
 
-function init(): void {
+function init(): void | false {
  const messageField = select('textarea#merge_message_field')!;
+ const originalMessage = messageField.value;
  const deduplicatedAuthors = new Set();
 
  // This method ensures that "Co-authored-by" capitalization doesn't affect deduplication
- for (const [, author] of messageField.value.matchAll(/co-authored-by: ([^\n]+)/gi)) {
+ for (const [, author] of originalMessage.matchAll(/co-authored-by: ([^\n]+)/gi)) {
  deduplicatedAuthors.add('Co-authored-by: ' + author);
  }
 
- messageField.value = [...deduplicatedAuthors].join('\n');
+ const cleanedMessage = [...deduplicatedAuthors].join('\n');
+ if (cleanedMessage === originalMessage.trim()) {
+ return false;
+ }
+
+ messageField.value = cleanedMessage;
+ messageField.after(
+ <p className="note rgh-sync-pr-commit-title-note">
+ The description field was cleared by <a target="_blank" href="https://github.com/refined-github/refined-github/wiki/Extended-feature-descriptions#clear-pr-merge-commit-message" rel="noreferrer">Refined GitHub</a>.
+ </p>,
+ <hr/>,
+ );
 }
 
 void features.add(import.meta.url, {