The primary defensive strategy for 2026 is the implementation of 'Linguistic Firewalls.' As demonstrated by the Gemini and Morris II threats, natural language is now a viable exploit code. Architects must deploy secondary, hardened LLMs whose sole purpose is to 'sanitize' incoming prompts. These firewalls use 'Adversarial Detection' models to identify imperative commands hidden within data strings. Furthermore, we must adopt 'Data-Instruction Segregation' (DIS) at the API level. This involves tagging all external inputs with 'low-trust' metadata, ensuring that the primary AI agent treats them as 'read-only' data rather than executable instructions. Finally, 'Human-in-the-Loop' (HITL) gates must be mandatory for any AI action that involves data deletion, financial transactions, or external communication. Security by design now means 'Security by Isolation'.