fix(channels): ignore hidden control messages when extracting replies (#3219) (#3270)

backend/app/channels/manager.py

@@ -173,6 +173,8 @@ def _extract_response_text(result: dict | list) -> str:
 
         # Stop at the last human message — anything before it is a previous turn
         if msg_type == "human":
+            if _is_hidden_human_control_message(msg):
+                continue
             break
 
         # Check for tool messages from ask_clarification (interrupt case)
@@ -313,6 +315,8 @@ def _extract_artifacts(result: dict | list) -> list[str]:
             continue
         # Stop at the last human message — anything before it is a previous turn
         if msg.get("type") == "human":
+            if _is_hidden_human_control_message(msg):
+                continue
             break
         # Look for AI messages with present_files tool calls
         if msg.get("type") == "ai":
@@ -325,6 +329,18 @@ def _extract_artifacts(result: dict | list) -> list[str]:
     return artifacts
 
 
+def _is_hidden_human_control_message(msg: Mapping[str, Any]) -> bool:
+    """Return whether a human message is an internal control message hidden from UI."""
+    if msg.get("type") != "human":
+        return False
+
+    additional_kwargs = msg.get("additional_kwargs")
+    if not isinstance(additional_kwargs, Mapping):
+        return False
+
+    return additional_kwargs.get("hide_from_ui") is True
+
+
 def _format_artifact_text(artifacts: list[str]) -> str:
     """Format artifact paths into a human-readable text block listing filenames."""
     import posixpath