When a panel member spawned a subagent via the Agent tool, the Claude CLI
emitted the subagent's internal steps as separate top-level messages
carrying parent_tool_use_id: tool_use blocks arrived as type:"assistant"
(no handler → dropped) and the matching tool_result as type:"user", which
created a nameless, label-less collapsible box in the frontend — both in
the live stream and in the persisted history (same segment source).
Skip any top-level event with a non-empty parent_tool_use_id at the single
stream JSON parser, so subagent internals never become CliStreamEvents.
This covers worker and panel-member paths at once. The Agent tool call
itself (parent_tool_use_id=null) stays visible, and the final result event
— which aggregates subagent tokens — carries no parent_tool_use_id, so the
token balance is unaffected.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
