Why it matters

Trust boundaries shape defense. Understanding shapes design.

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The architecture

Identify zones + boundaries.

Enforce filtering + validation at boundaries.

Least-privilege across.

Trust boundariesTrust zonesidentifyBoundariesfilter + validateCross-boundary controlsleast-privUntrusted-side inputs always need validation; treat retrieved as untrusted
Trust boundaries.
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How it works end to end

User + retrieved data + tool output = untrusted.

System prompt + business logic = trusted.

Guard crossings.