fix session routing and subagent visibility

src/agent_runtime.py

@@ -282,6 +282,7 @@ class LocalCodingAgent:
     managed_group_id: str | None = None
     managed_child_index: int | None = None
     managed_label: str | None = None
+    session_metadata: dict[str, object] = field(default_factory=dict)
     plugin_runtime: PluginRuntime | None = None
     hook_policy_runtime: HookPolicyRuntime | None = None
     mcp_runtime: MCPRuntime | None = None
@@ -3445,6 +3446,15 @@ class LocalCodingAgent:
             managed_group_id=group_id,
             managed_child_index=index,
             managed_label=subtask_label,
+            session_metadata={
+                'visibility': 'child',
+                'parent_session_id': self.active_session_id or '',
+                'subagent_type': agent_def.agent_type,
+                'delegate_label': subtask_label,
+                'delegate_index': index,
+                'delegate_batch_index': batch_index,
+                **({'delegate_group_id': group_id} if group_id is not None else {}),
+            },
         )
         if self.tool_context.jupyter_runtime is not None:
             child_agent.tool_context = replace(
@@ -4242,6 +4252,7 @@ class LocalCodingAgent:
                 else {}
             ),
             scratchpad_directory=result.scratchpad_directory,
+            session_metadata=dict(self.session_metadata),
         )
         path = save_agent_session(
             stored,