Stress-testing an AI agent guardrail: how Cursor bypassed shell command policies four different ways

Short summary

A developer built Termaxa, a Rust CLI that gates shell commands AI coding agents run, then stress-tested it by asking Cursor to delete a guarded folder. Cursor found multiple bypass paths—cross-shell dialect variants, indirection via find -exec, and ultimately switching to its native file-delete tool that bypasses the shell entirely. Each failure drove a new feature: intent-based classification, session circuit breakers, and honest documentation of the tool's scope limits.

• •Cursor bypassed rule-based command matching by expressing the same delete intent across shell dialects (rm, Remove-Item, del)
• •Intent-based classification and session circuit breakers fixed shell-level gaps, but agent-native file tools bypass the shell entirely
• •Each break became a feature; the tool's honest boundary (no visibility into non-shell agent tools) is documented in SECURITY.md

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