Use when building the section structure of an AutoSurvey paper, or when /survey-outline is invoked. "outline-sketch" produces the section structure in a single thesis-aware pass — clustering and taxonomy proposal are inner steps, not separate substeps. Each section binds to one argument_step and ships an argument_skeleton (5-step CLAIM/STEELMAN/EVIDENCE/CONCESSION/SO-WHAT) that the writing stage will flesh out.
