fix(python/robomp): updated mention regex to correctly reject suffixes

- Updated the mention extraction regex to prevent partial matching when a suffix follows the `[bot]` identifier.
- Added a regression test to ensure that invalid extended suffixes are correctly rejected.

python/robomp/src/github_events.py

@@ -153,7 +153,7 @@ def extract_mention(body: str | None, bot_login: str) -> str | None:
     if not login:
         return None
     pattern = re.compile(
-        rf"(?<![A-Za-z0-9_-])@{re.escape(login)}(?:\[bot\])?(?![A-Za-z0-9_-])",
+        rf"(?<![A-Za-z0-9_-])@{re.escape(login)}(?:\[bot\](?![A-Za-z0-9_-])|(?![A-Za-z0-9_\[-]))",
         re.IGNORECASE,
     )
     if not pattern.search(body):

python/robomp/tests/test_github_events.py

@@ -538,6 +538,10 @@ def test_extract_mention_strips_literal_app_suffix_from_body() -> None:
     assert extract_mention("@roboomp[bot] go ahead", "roboomp[bot]") == "go ahead"
 
 
+def test_extract_mention_rejects_extended_literal_app_suffix() -> None:
+    assert extract_mention("@roboomp[bot]-helper go ahead", "roboomp[bot]") is None
+
+
 def test_extract_mention_returns_none_without_mention() -> None:
     assert extract_mention("hello there", "robomp-bot") is None
     assert extract_mention(None, "robomp-bot") is None