Fires when a fellow is ready to design how the AI product is actually built — "architect the product", "how do we build the AI system", "design the AI system", "what's the system architecture", "what does the stack look like". Returns a compound-system architecture (input → router → retrieve/reason/act → validate & guardrails → output over a data layer), a 40/20/30/10 effort-allocation plan, and named model-swap points, then kills any monolithic one-big-prompt design. Do NOT fire to write the pass/fail scope (use eval-first-spec), to render the HTML/SVG picture (use design/architecture-diagram), or to argue defensibility (use moat-design-canvas).
