fix(streaming): preserve recovered segments across channels

nanobot/channels/telegram/runtime.py

@@ -931,6 +931,10 @@ class TelegramChannel(BaseChannel):
         meta = metadata or {}
         int_chat_id = int(chat_id)
 
+        if stream_end and merge_next:
+            if not delta:
+                return
+            stream_end = False
         if stream_end:
             buf = self._stream_bufs.get(chat_id)
             if not buf or not buf.message_id or not buf.text:

nanobot/channels/telegram/tests/test_telegram_channel.py

@@ -675,6 +675,33 @@ async def test_send_delta_stream_end_raises_and_keeps_buffer_on_failure() -> Non
     assert "123" in channel._stream_bufs
 
 
+@pytest.mark.asyncio
+async def test_send_delta_merge_next_preserves_buffer() -> None:
+    channel = TelegramChannel(
+        TelegramConfig(enabled=True, token="123:abc", allow_from=["*"]),
+        MessageBus(),
+    )
+    channel._app = _FakeApp(lambda: None)
+    channel._app.bot.edit_message_text = AsyncMock()
+    channel._stream_bufs["123"] = _StreamBuf(
+        text="first-",
+        message_id=7,
+        last_edit=float("inf"),
+        stream_id="s:0",
+    )
+
+    await channel.send_delta(
+        "123",
+        "boundary",
+        stream_id="s:0",
+        stream_end=True,
+        merge_next=True,
+    )
+
+    assert channel._stream_bufs["123"].text == "first-boundary"
+    channel._app.bot.edit_message_text.assert_not_awaited()
+
+
 @pytest.mark.asyncio
 async def test_send_delta_stream_end_treats_not_modified_as_success() -> None:
     from telegram.error import BadRequest