diff --git a/backend/app/channels/telegram.py b/backend/app/channels/telegram.py
index 6b6b52d9ce..04e1171913 100644
--- a/backend/app/channels/telegram.py
+++ b/backend/app/channels/telegram.py
@@ -376,7 +376,13 @@ class TelegramChannel(Channel):
         # actually contains a rich construct. Structured command/error replies
         # are plain text with none, so they stay plain and their newlines and
         # <placeholder> tokens are not collapsed into one line.
-        return bool(self.config.get("rich_messages")) and 0 < len(text) <= TELEGRAM_MAX_RICH_MESSAGE_LENGTH and _has_rich_constructs(text)
+        if not self.config.get("rich_messages"):
+            return False
+        # Telegram measures this cap in UTF-16 code units like its other limits, while
+        # `len()` counts code points, so reuse the bounded scan the plain-text path
+        # uses: an emoji-heavy reply that fits by code points is still rejected.
+        _, over_limit = _first_utf16_chunk(text, TELEGRAM_MAX_RICH_MESSAGE_LENGTH)
+        return not over_limit and _has_rich_constructs(text)
 
     async def _edit_rich_message(self, chat_id: int, message_id: int, text: str) -> bool:
         """Replace a streamed preview with a persistent Telegram Rich Message."""
diff --git a/backend/tests/test_telegram_message_length.py b/backend/tests/test_telegram_message_length.py
index b1baa86d6a..b007454b44 100644
--- a/backend/tests/test_telegram_message_length.py
+++ b/backend/tests/test_telegram_message_length.py
@@ -140,3 +140,28 @@ def test_stream_update_clips_without_measuring_the_whole_reply(monkeypatch):
     assert display.endswith("…")
     # Bounded by the limit twice (measure against it, then clip one unit shorter), not by 200,000 characters.
     assert measured <= 2 * (TELEGRAM_MAX_MESSAGE_LENGTH + 1)
+
+
+def _rich_channel():
+    ch, bot = _channel_with_bot()
+    ch.config["rich_messages"] = True
+    return ch, bot
+
+
+def test_rich_send_is_refused_when_the_reply_crosses_the_utf16_rich_limit():
+    """The rich-message cap is measured in code units too, so an emoji-heavy reply cannot pass a code-point check."""
+    ch, _ = _rich_channel()
+    # Half the limit in emoji plus a bold construct: under the cap by code points, over it by code units.
+    text = EMOJI * (telegram.TELEGRAM_MAX_RICH_MESSAGE_LENGTH // 2) + "**x**"
+
+    assert len(text) < telegram.TELEGRAM_MAX_RICH_MESSAGE_LENGTH
+    assert utf16_units(text) > telegram.TELEGRAM_MAX_RICH_MESSAGE_LENGTH
+    assert ch._can_send_rich(text) is False
+
+
+def test_rich_send_is_still_offered_inside_the_utf16_rich_limit():
+    ch, _ = _rich_channel()
+    text = EMOJI * 10 + "**x**"
+
+    assert utf16_units(text) == 25
+    assert ch._can_send_rich(text) is True