1. Introduction

2. Theoretical Background and Conceptual Definitions

3. The Single-Player-but-Not-Solitary Loop

4. Zombie Tasks: When Delegated Work Reveals Itself as Fake Work

5. Conclusion

Collaborative software has traditionally been thought to require single-player value: one user must benefit before others arrive. This study argues that in agentic artificial intelligence (AI) products, the thesis is necessary but insufficient. Because the user delegates work to a non-human counterpart and must decide what can be entrusted to it, the individual-use phase is a relational loop rather than an isolated utility loop. The study proposes the single-player-but-not-solitary loop and specifies credible presence: the quality by which an agent’s activity can be verified as work rather than merely appearing to be so. Drawing on Luhmann’s account of trust as complexity reduction and distinguishing trust from calibrated reliance, it defines the zombie task, a delegated task whose resource consumption outlives the intention that justified it, and analyzes its two subtypes and three strata of loss. Four design principles emerge from this analysis: responsible stopping, transparent state-sharing, ownable artifacts, and auditability.