Show HN: Semantic Overlays – an NX bit for LLM prompt injection (live demo)

By joshua_s_penman · 2026-09-01 · 3 points · 0 comments

https://semantic-overlays.vercel.app/

I've built a new method for steering LLMs called Semantic Overlays, small trained adapters on a frozen model which change how it perceives a piece of its context. The most readily applicable usage is to mitigate prompt injection, and it lets us take a very-injectable Qwen-3.5-9B…

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