A Formal Theory of Work Custody

This paper proposes Work Custody as a first-class collaboration relation identifying which eligible participant currently holds the bounded operational duty to advance a particular version and scope of a work object. Custody answers "who has the next move?" without collapsing ownership, assignment, authority, accountability, capability, or standing. The model replaces an informal linear status list with a generation-bound state machine. Offers, acceptances, transfers, releases, revocations, expirations, completion, blockage, and recovery are typed transitions. A normal transfer is a handshake: the predecessor remains primary until the successor accepts and the transfer is promoted. Forced revocation or failure may create an explicit unassigned or recovery-required state; the system preserves accountability for the discontinuity rather than pretending custody never had a gap. Custody is queryable only relative to exact work identity, version, scope, valid time, transaction time, jurisdiction, and authorization. Receipts bind declarations and observations but do not by themselves prove complete mediation or actual effect. Human and machine participants may share transition syntax while differing in capability, persistence, consent, legal personality, and moral accountability. The resulting specification supports agent orchestration, cold-boot continuity, governed project memory, and cross-node handoff. It remains a candidate architecture: implementation conformance, organizational benefit, complexity reduction, and comparative performance require exact configurations and empirical evidence.