Published onSeptember 9, 2026How I Let a Prompt Injection Succeed and Still Blocked the 50,000 Euro DiscountAILLMsPolicy-as-CodeOPASecurityPythonEngineeringAgentic-AIA retrieved document made the model propose a 50,000 euro discount. The prompt injection succeeded, but the action did not. Here is the deterministic policy boundary that stopped it. Part 3 of From Prompt to Proof.