Mirror-Rite is a work for ‘meta-trumpet’, computer and live electronics. The composition is neither notated nor stored, but forms itself as a complex of rule-based structures, transformations and processes around the improvisation of a live performer, its source of both energy and material. This article discusses the ways in which these algorithms deal with interactivity and projection in time, and how the handling of these aspects might permit the assembly of algorithmic elements into a complex dynamic whole, sensitive to (and existing solely within) present circumstances, but demonstrating unity between different performances.