understanding-stability-inference

Compose compiler stability inference works by evaluating classes and composable parameters through a 12-phase algorithm to determine if they are stable, runtime stable, or unstable. This classification dictates how the compiler skips recomposition for unchanged parameters.

The Compose compiler may mark a class as unstable due to generics stability rules or separate compilation boundaries where the compiler cannot guarantee known-stable constructs. Diagnosing this requires checking the specific inference algorithm phase that triggered the unstable classification.

The Compose compiler defines five stability types: Certain, Runtime, Unknown, Parameter, and Combined. Each type represents a different level of confidence the compiler has in a class or parameter's mutability during recomposition.

To diagnose unexpected Compose stability classifications, analyze the class against the 12-phase inference algorithm. This process provides the rationale for why the compiler assigned a specific stability type, such as Runtime or Unknown, to your composable parameters.

You need to worry about runtime stability when the compiler cannot guarantee stability at compile time, often due to separate compilation. The Compose compiler assigns a Runtime stability type, deferring the stability check to execution rather than treating it as a known-stable construct.