Senior Bubble + Supabase Developer

B2B Wholesale Marketplace: Senior Bubble + Supabase Dev Building an API-heavy tech liquidation platform. This is a high-security financial app—not standard e-commerce. You must build a decoupled architecture to minimize Bubble WU costs. Tech Stack: Front: Bubble.io Backend: Supabase (Mandatory) Payments: Paystack API (Dedicated Virtual Accounts for inbound deposits ONLY. No automated outbound transfers). Core Features: 1 Registration Wall: Approval-only access. 2 Escrow Wallet: Auto-generate DVA bank accounts, process webhooks, and manage a database ledger. 3 Bidding Engine: Live auction timers and manifests. 4 Admin Panel: Dashboard to view pending manual payouts. Requirements: Proven Bubble-to-Supabase API experience. Deep understanding of backend security to prevent race conditions. TO APPLY: Answer this at the top: Even though payouts are processed manually by the admin, exactly how would you structure the backend workflow so a user cannot click "Request Withdrawal" 10 times in 1 second, creating 10 pending requests that exceed their actual balance?