1. Introduction to the Linear Paradigm in API Design In the design of safety-critical systems, the management of resource lifecycles represents the primary vector for catastrophic failure. Traditional API design relies heavily on "implicit lifecycles"—a reliance on programmer discipline to ensure that resources like memory, file handles, and sockets are acquired and released in the correct order. This approach is fundamentally fragile. The strategic shift toward the linear paradigm moves these guarantees from the fallible human mind to the uncompromising enforcement of the compiler. Where traditional APIs assume a developer will adhere to documentation, linear APIs automate correctness.Central to this is the Use-Once Rule . In Austral, a linear type is one whose values must be consumed exactly once. They cannot be used zero times (preventing leaks) nor can they be used multiple times (preventing use-after-free or double-close errors).…