Turn an accepted kitsoki proposal (or an epic + its children) into a validated, reviewed YAML decomposition of right-sized agent briefs. Use when the user wants to decompose work into briefs, "break this proposal into tickets/tasks", produce a decomposition.yaml, or check out the brief-manifest shape from docs/proposals/work-decomposition.md before that pipeline is built as a story. Drives discovery → manifest → deterministic structural lint → adversarial feasibility/completeness review, by hand.