fix(streaming): preserve recovered segments across channels

nanobot/channels/feishu/runtime.py

@@ -2232,6 +2232,10 @@ class FeishuChannel(BaseChannel):
         rid_type = "chat_id" if chat_id.startswith("oc_") else "open_id"
 
         # --- stream end: final update or fallback ---
+        if stream_end and merge_next:
+            if not delta:
+                return
+            stream_end = False
         if stream_end:
             message_id = meta.get("message_id")
             # Only finalize the OnIt -> DONE reaction transition on the truly

nanobot/channels/feishu/tests/test_feishu_streaming.py

@@ -285,6 +285,27 @@ class TestSendDelta:
         settings_call = ch._client.cardkit.v1.card.settings.call_args[0][0]
         assert settings_call.body.sequence == 5  # after final content seq 4
 
+    @pytest.mark.asyncio
+    async def test_stream_end_merge_next_preserves_buffer(self):
+        ch = _make_channel()
+        ch._stream_bufs["oc_chat1"] = _FeishuStreamBuf(
+            text="first-",
+            card_id="card_1",
+            sequence=3,
+            last_edit=time.monotonic(),
+        )
+
+        await ch.send_delta(
+            "oc_chat1",
+            "boundary",
+            stream_end=True,
+            merge_next=True,
+        )
+
+        assert ch._stream_bufs["oc_chat1"].text == "first-boundary"
+        ch._client.cardkit.v1.card_element.content.assert_not_called()
+        ch._client.cardkit.v1.card.settings.assert_not_called()
+
     @pytest.mark.asyncio
     async def test_stream_end_fallback_when_no_card_id(self):
         """If card creation failed, stream_end falls back to a plain card message."""