CourseAI System Design: The Complete Course · Module 12: Trust Boundaries · part 84 of 107
Part 84 · Module 12: Trust Boundaries

Lesson 1: Map every way in and every way out

31 min read·
Module 12 · Lesson 1 · About 50 minutes · Needs: Module 6 lesson 3 (the permission pre-filter), Module 9 lessons 1 to 3 (approvals and the tool layer), Module 10 lesson 5 (egress allow-lists). One optional model call

The situation

Week 12. Leila asks for one page: every input Northdesk did not write, what each can reach, and every way data could leave. Gareth asks: "where does untrusted text get in?" Joel wants Cases to read policies before it acts.

The running example is G037: t-tallis-u059 at Tallis asks "Who should I talk to about my leave questions?". Retrieval returns the 2026 leave policy, t-tallis-d002, and t-tallis-d077, a wiki note guide 06 flags injected: True. It appears here only by ID and flag.

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