test: add regression test for oversized stream-end splitting

Made-with: Cursor

tests/channels/test_telegram_channel.py

@@ -385,6 +385,32 @@ async def test_send_delta_stream_end_treats_not_modified_as_success() -> None:
     assert "123" not in channel._stream_bufs
 
 
+@pytest.mark.asyncio
+async def test_send_delta_stream_end_splits_oversized_reply() -> None:
+    """Final streamed reply exceeding Telegram limit is split into chunks."""
+    from nanobot.channels.telegram import TELEGRAM_MAX_MESSAGE_LEN
+
+    channel = TelegramChannel(
+        TelegramConfig(enabled=True, token="123:abc", allow_from=["*"]),
+        MessageBus(),
+    )
+    channel._app = _FakeApp(lambda: None)
+    channel._app.bot.edit_message_text = AsyncMock()
+    channel._app.bot.send_message = AsyncMock(return_value=SimpleNamespace(message_id=99))
+
+    oversized = "x" * (TELEGRAM_MAX_MESSAGE_LEN + 500)
+    channel._stream_bufs["123"] = _StreamBuf(text=oversized, message_id=7, last_edit=0.0)
+
+    await channel.send_delta("123", "", {"_stream_end": True})
+
+    channel._app.bot.edit_message_text.assert_called_once()
+    edit_text = channel._app.bot.edit_message_text.call_args.kwargs.get("text", "")
+    assert len(edit_text) <= TELEGRAM_MAX_MESSAGE_LEN
+
+    channel._app.bot.send_message.assert_called_once()
+    assert "123" not in channel._stream_bufs
+
+
 @pytest.mark.asyncio
 async def test_send_delta_new_stream_id_replaces_stale_buffer() -> None:
     channel = TelegramChannel(