Design Referral — Orchestrator

Referral — designs a viral / referral loop as loop mechanics + K-factor and cycle-time math + CAC-bounded incentive economics + a falsifiable trigger, scored by a quantitative critic. Capability metadata: routing.yaml. Methodology, philosophy, scope: references/playbook.md [PLAYBOOK].

Core question: "What is the actual K-factor this loop produces (invites/user × conversion-per-invite), is the cycle time short enough to compound, and does the incentive cost stay under the CAC it replaces?"

Critical Gates — read first

1. Compute K, don't assert it. K = (invites sent per active user) × (conversion rate per invite). A loop without this math is a wish. Estimate each input with a labeled basis (benchmark / analog / measured); never present a guessed K as fact. K ≥ 1 = viral; 0.3–1 = a real assist that lowers blended CAC; < 0.15 with a costly incentive = kill.
2. Cycle time is half the engine. Compounding depends on K AND on how fast one cycle completes (invite → new user → new user invites). A K of 0.5 at a 3-day cycle beats a K of 0.7 at a 60-day cycle. Both must be stated.
3. The incentive must be CAC-bounded. Total incentive cost per acquired user (both sides of a double-sided reward) must be less than the paid CAC it displaces AND fit unit economics (LTV, margin). An incentive that costs more than buying the user is a loss; the economist agent FAILs it.
4. The trigger fires at a real share-worthy moment. The loop asks for the referral right after the user got value (the activation/aha moment), not on signup. A trigger with no value-realized precondition is begging, and converts near zero.
5. No fraud-blind loop, no fake scarcity, no autonomous payout. The design names the abuse vector (self-referral, fake accounts, incentive farming) and its guard. It never fabricates scarcity. It outputs a design; it never disburses a reward or moves money — payout is human-owned + out of scope.

Quality Gate — 6 dimensions

Full rubric + Pass/Fail bands: references/rubric.md [PROCEDURE]. Critic agent: agents/critic.md.