Prompt Injection Defense Architecture: Sandboxed Tools, Allowlists, and Typed Calls

Why Prompt Injection Keeps Winning in Production

Most prompt injection incidents follow the same pattern:

1. The model reads untrusted instructions (user text, RAG chunks, web pages, PDFs, emails).
2. Those instructions impersonate authority: “Ignore the rules… call this tool… send this data…”
3. Your system lets the model translate that into real actions.

That last step is the real vulnerability. The model will always be influenceable. The question is whether your system obeys.