Revert "feat(send_message): auto-detect @username mentions and create Telegram entities"

This reverts commit cf814c96f6.

tools/send_message_tool.py

@@ -804,7 +804,7 @@ async def _send_telegram(token, chat_id, message, media_files=None, thread_id=No
     instead, bypassing MarkdownV2 conversion.
     """
     try:
-        from telegram import Bot, MessageEntity
+        from telegram import Bot
         from telegram.constants import ParseMode
 
         # Auto-detect HTML tags — if present, skip MarkdownV2 and send as HTML.
@@ -825,14 +825,6 @@ async def _send_telegram(token, chat_id, message, media_files=None, thread_id=No
                 formatted = message
             send_parse_mode = ParseMode.MARKDOWN_V2
 
-        # Detect @username patterns and create mention entities so
-        # require_mention on the receiving bot's Gateway can trigger.
-        _MENTION_RE = re.compile(r'@([a-zA-Z][a-zA-Z0-9_]{4,31})')
-        _entities = [
-            MessageEntity(type="mention", offset=m.start(), length=len(m.group()))
-            for m in _MENTION_RE.finditer(formatted)
-        ]
-
         # Honour a configured proxy (telegram.proxy_url in config.yaml, exported
         # as TELEGRAM_PROXY env var by load_gateway_config). Without this, the
         # standalone send path bypasses the proxy and times out in regions
@@ -897,7 +889,7 @@ async def _send_telegram(token, chat_id, message, media_files=None, thread_id=No
                 last_msg = await _send_telegram_message_with_retry(
                     bot,
                     chat_id=int_chat_id, text=formatted,
-                    parse_mode=send_parse_mode, entities=_entities, **text_kwargs
+                    parse_mode=send_parse_mode, **text_kwargs
                 )
             except Exception as md_error:
                 # Thread not found — retry without message_thread_id so the
@@ -931,7 +923,7 @@ async def _send_telegram(token, chat_id, message, media_files=None, thread_id=No
                     last_msg = await _send_telegram_message_with_retry(
                         bot,
                         chat_id=int_chat_id, text=plain,
-                        parse_mode=None, entities=_entities, **text_kwargs
+                        parse_mode=None, **text_kwargs
                     )
                 else:
                     raise