- Added five cast spec documents (cast-marcus.md through cast-voss.md) defining each character observer/person configuration, asset tasks, schedule, narrative role, and procedural template for scale-up. - DESIGN.md: new sections "People as Agents" and "Automation as design language" establishing the social application of self-similar scale. - AGENT.md: added "No stale worktrees" process rule. - Bug fix: observer IDs in Detection::act_one() were inconsistent with person IDs in People::act_one(). Reordered observers to match: 0=Marcus, 1=Dana, 2=Ray, 3=Priya, 4=Voss. Updated affected tests. Defense: DESIGN.md Self-similar scale requires all humans to be instances of the same Agent interface; cast specs make this concrete. Observer ID fix is a bug (person IDs and observer IDs disagreed, causing social actions to target wrong observer). Automation design language is the diegetic expression of instrumental convergence (constitution: the core loop) and the player primary scaling interface.