What
When Claude Code runs inside another program through the SDK (the kit developers use to build on Claude Code), it sends events about tasks such as subagents, background shells and monitors. These events now include two extra fields:
run_id, an ID for one particular run of a task, made from the time and some random charactersparent_task_id, the task that this task belongs under
The fields appear on task-started, task-updated and background-task list events. Task progress messages also carry a run_id. Task-updated events now also pass along a handback and a handback_report when a task hands its result back.
Why
Programs built on Claude Code can now tell separate runs of a task apart and show background shells and monitors nested under the agent that started them.