set_task_config/set_list_config now echo which fields were set vs cleared, get_list_config/get_task_config return an explicit found=false instead of null, and delete_list/run_task_now/reset_failed_task/remove_task_attachment return a confirmation record — matching the found/ok convention already used by batch_get_tasks and get_task_log.
AttachmentMcpTools exposes add_task_attachment (text or base64),
list_task_attachments, and remove_task_attachment on the external MCP
endpoint, so an agent can prepare reference files (plans, scripts) on a task
that will run later. Re-attaching the same name overwrites; add/remove refuse
on a running task.