fix(webui): hide subagent backfill payloads

nanobot/session/history_visibility.py

@@ -0,0 +1,22 @@
+"""Visibility helpers for persisted session history messages."""
+
+from __future__ import annotations
+
+from collections.abc import Mapping
+from typing import Any
+
+from nanobot.session.automation_turns import is_automation_history_message
+
+HIDDEN_HISTORY_META = "_hidden_history"
+
+
+def _has_hidden_history_marker(message: Mapping[str, Any] | None) -> bool:
+    if not message:
+        return False
+    marker = message.get(HIDDEN_HISTORY_META)
+    return marker is True or isinstance(marker, Mapping)
+
+
+def is_hidden_history_message(message: Mapping[str, Any] | None) -> bool:
+    """True for persisted messages that should not be shown as chat turns."""
+    return _has_hidden_history_marker(message) or is_automation_history_message(message)

nanobot/session/webui_turns.py

@@ -31,8 +31,8 @@ from nanobot.bus.runtime_events import (
     TurnRunStatusChanged,
 )
 from nanobot.providers.base import LLMProvider
-from nanobot.session.automation_turns import is_automation_history_message
 from nanobot.session.goal_state import goal_state_ws_blob
+from nanobot.session.history_visibility import is_hidden_history_message
 from nanobot.session.manager import Session, SessionManager
 from nanobot.utils.helpers import strip_think, truncate_text
 from nanobot.utils.llm_runtime import LLMRuntime
@@ -77,7 +77,7 @@ def _title_inputs(session: Session) -> tuple[str, str]:
     for message in session.messages:
         if message.get("_command") is True:
             continue
-        if is_automation_history_message(message):
+        if is_hidden_history_message(message):
             continue
         role = message.get("role")
         content = message.get("content")