fix(telegram): improve MarkdownV2 edit fallback and fix _strip_mdv2 bold handling

When edit_message(finalize=True) fails with a MarkdownV2 parse error,
the silent fallback previously sent raw content with escape sequences.
Now it logs the error and strips markdown formatting via _strip_mdv2()
for clean plain-text fallback.

Also fixes _strip_mdv2 to handle standard markdown bold (\*\*text\*\*)
before MarkdownV2 bold (\*text\*), preventing half-stripped asterisks.

Refs: #41955, #41732

gateway/platforms/telegram.py

@@ -181,6 +181,8 @@ def _strip_mdv2(text: str) -> str:
     """
     # Remove escape backslashes before special characters
     cleaned = re.sub(r'\\([_*\[\]()~`>#\+\-=|{}.!\\])', r'\1', text)
+    # Remove standard markdown bold (**text** → text) BEFORE MarkdownV2 bold
+    cleaned = re.sub(r'\*\*([^*]+)\*\*', r'\1', cleaned)
     # Remove MarkdownV2 bold markers that format_message converted from **bold**
     cleaned = re.sub(r'\*([^*]+)\*', r'\1', cleaned)
     # Remove MarkdownV2 italic markers that format_message converted from *italic*
@@ -2208,11 +2210,17 @@ class TelegramAdapter(BasePlatformAdapter):
                 # "Message is not modified" is a no-op, not an error
                 if "not modified" in str(fmt_err).lower():
                     return SendResult(success=True, message_id=message_id)
-                # Fallback: retry without markdown formatting
+                # Fallback: strip MarkdownV2 escapes and retry as clean plain text
+                logger.warning(
+                    "[%s] MarkdownV2 edit failed, falling back to plain text: %s",
+                    self.name,
+                    fmt_err,
+                )
+                _plain = _strip_mdv2(content) if content else content
                 await self._bot.edit_message_text(
                     chat_id=int(chat_id),
                     message_id=int(message_id),
-                    text=content,
+                    text=_plain,
                 )
             return SendResult(success=True, message_id=message_id)
         except Exception as e:

tests/gateway/test_telegram_format.py

@@ -835,7 +835,7 @@ class TestEditMessageStreamingSafety:
         assert second_call == {
             "chat_id": 123,
             "message_id": 456,
-            "text": "final **bold**",
+            "text": "final bold",
         }
 
     @pytest.mark.asyncio