Alice attempts a ₦500,000 transfer to Bob. Your platform's velocity threshold for her tier is ₦200,000 per hour. The transfer cannot post normally, it goes into a manual review queue. Your ops team gets paged, reviews the transaction, either approves (releases to Bob) or rejects (returns to Alice). The queue is a real liability account on your books; its depth is a real-time risk metric. This pairs with Lesson 6 (authorization hold), the structure is identical, but the gate is a HUMAN approval instead of a provider response.