fix(agent): preserve none vs unknown tool effects (#61783)

* fix(agent): persist truthful tool effect dispositions

* fix(agent): preserve successful siblings during orphan recovery

* fix(agent): narrow effect dispositions to none and unknown

agent/tool_dispatch_helpers.py

@@ -359,7 +359,13 @@ def _trajectory_normalize_msg(msg: Dict[str, Any]) -> Dict[str, Any]:
     return msg
 
 
-def make_tool_result_message(name: str, content: Any, tool_call_id: str) -> dict:
+def make_tool_result_message(
+    name: str,
+    content: Any,
+    tool_call_id: str,
+    *,
+    effect_disposition: str | None = None,
+) -> dict:
     """Build a tool-result message dict with both the OpenAI-format ``name``
     field (required by the wire format and provider adapters) and the internal
     ``tool_name`` field (written to the session DB messages table).
@@ -394,6 +400,8 @@ def make_tool_result_message(name: str, content: Any, tool_call_id: str) -> dict
     else:
         if risk_metadata is not None:
             message["_tool_output_risk"] = risk_metadata
+    if effect_disposition is not None:
+        message["effect_disposition"] = effect_disposition
     return message