Anthropic Ships Claude Opus 5 as 'Least Prompt-Injectable' Model — Then Its Steering Prompts Leak Days Later

Anthropic launched Claude Opus 5 with a pitch centered on coding, agents, and prompt-injection resistance. Within days, accounts report the model's internal steering prompts are being reverse-engineered and shared.

Anthropic's newest flagship arrived with a marketing spine built around trust. According to @marcopapa99, Claude Opus 5 is "being framed around stronger coding, agents, and professional work," and Anthropic is positioning it as "its least prompt-injectable model yet." In an agent world where a single injected instruction can redirect an autonomous system, that resistance is arguably the most valuable feature a model can advertise.

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