Three Classes of Guardrail Erosion Resistance

Guardrails fall into three classes by erosion resistance: erasable (convention-dependent), detectable (tool-enforced), and immutable (formally enforced). Social guardrails (documentation, naming conventions, architectural patterns as “how we do things”) erode fastest because the suggestible actor walks through conventions without noticing. Encoded guardrails (linters, static analysis, CI/CD gates) erode moderately because agents respond to errors but can satisfy checks trivially without satisfying the underlying invariant. Structural guardrails (type systems, capability restrictions, property-based tests, formal verification) resist erosion because they encode mathematical properties that cannot be circumvented by pattern-matching.

Most guardrails prescribed in the Suggestible Actor post are social or encoded. The only erosion-resistant class is structural, which most codebases have very little of.