fix(tui): address Copilot round-2 on #14045

- delegate_task: use shared tool_error() for the paused-spawn early return
  so the error envelope matches the rest of the tool.
- Disk snapshot label: treat orphaned nodes (parentId missing from the
  snapshot) as top-level, matching buildSubagentTree / summarizeLabel.

tools/delegate_tool.py

@@ -1489,13 +1489,9 @@ def delegate_task(
     # when a runaway tree is detected, without interrupting already-running
     # children.  Cleared via the matching `delegation.pause` RPC.
     if is_spawn_paused():
-        return json.dumps(
+        return tool_error(
-            {
+            "Delegation spawning is paused. Clear the pause via the TUI "
-                "error": (
+            "(`p` in /agents) or the `delegation.pause` RPC before retrying."
-                    "Delegation spawning is paused. Clear the pause via the TUI "
-                    "(`p` in /agents) or the `delegation.pause` RPC before retrying."
-                )
-            }
         )
 
     # Normalise the top-level role once; per-task overrides re-normalise.

ui-tui/src/app/createGatewayEventHandler.ts

@@ -66,7 +66,12 @@ export function createGatewayEventHandler(ctx: GatewayEventHandlerContext): (ev:
         return min === 0 ? s.startedAt : Math.min(min, s.startedAt)
       }, 0)
 
-      const top = subagents.filter(s => !s.parentId).slice(0, 2)
+      // Match buildSubagentTree semantics: an agent is top-level if it has
+      // no parent OR its parent isn't in the snapshot (orphan).  Otherwise
+      // the disk label would fall back to `${N} subagents` for any turn
+      // whose roots got pruned mid-flight.
+      const ids = new Set(subagents.map(s => s.id))
+      const top = subagents.filter(s => !s.parentId || !ids.has(s.parentId)).slice(0, 2)
 
       const label = top.length
         ? top