Who Has the Ball?

Modern collaboration systems successfully model many aspects of cooperative work, including projects, documents, conversations, tasks, ownership, permissions, workflows, and automation. Yet they routinely fail to answer one of the simplest operational questions: Who has the ball? This question is deceptively fundamental. It does not ask who owns a project, who is accountable for an outcome, who was originally assigned a task, or who possesses authority over a resource. Rather, it asks who currently holds the live responsibility, context, and expectation to advance a particular unit of work. Existing collaboration systems approximate this concept through fragmented mechanisms such as assignees, ownership fields, Kanban cards, RACI matrices, incident handoffs, or chain-of-custody procedures. However, these mechanisms typically model planning, accountability, or artifact provenance rather than the current possession of responsibility-bearing work. This paper proposes Work Custody as a first-class primitive of collaboration. Work Custody is a temporally bounded constitutional relation describing which participant or execution role presently holds an accepted, scoped obligation to advance a work object, how custody is acquired and transferred, and how the collaboration system maintains shared queryable recognition among authorized participants. The record does not itself confer capability, authority, accountability, or moral or legal responsibility. The proposed protocol grammar can be used across human-human, human-agent, and agent-agent collaboration, while participant type, capability, authority, accountability, and legal or moral responsibility remain distinct. It offers a candidate operational primitive for constitutional collaboration environments.