Card 3 scope amendment (Tommy directive 2026-05-15, /sixis-pickup 8b51649a): SKIP real Stripe integration — Stripe account registration deferred to a later cycle. Replace /api/stripe/webhook + Stripe Checkout with synthetic-walkthrough placeholder: a server-side /api/payments/simulate-completed endpoint that mimics the eventual real-Stripe webhook contract (event-like payload {sim_event_id,user_id,amount_minor}; calls ledger.post_transaction with idempotency_key='synthetic:<sim_event_id>'; credit user available, debit platform_float at locked rate $1=10 GC; age-verified gate enforced inside RPC, returns 200 with logged audit row on unverified). UI shows a 'Simulate Stripe checkout' button on /wallet (and landing-page founding-member tier section) that calls this endpoint. Real-Stripe cutover later is single-file swap: endpoint rename, add Stripe signature verify middleware, idempotency-prefix swap to 'stripe:', wrap in ledger.stripe_purchase_complete(p_event_id,p_user_id,p_amount_minor). Tier-2 pre-ratified by sovereign per convergence_equals_ratification feedback rule.