understanding-stability-inference

The Compose compiler classifies a class as unstable when its properties are mutable or when cross-module types lack sufficient stability inference metadata. The 12-phase algorithm evaluates generics, known stable constructs, and recursive structures to determine the final verdict.

Compose stability inference handles generics and cross-module types using runtime checks via the `$stable` field and `@StabilityInferred` annotations. This separate compilation mechanism ensures types from external modules are evaluated correctly during recomposition.

The `$stable` field is a bitmask-encoded marker generated by the Compose compiler to communicate stability across modules. It enables runtime stability checks, allowing the compiler to make accurate recomposition decisions for types compiled in separate modules.

Diagnose a composable parameter marked as Runtime or Unknown by tracing it through the 12-phase stability inference algorithm. Check the Known Stable Constructs registry and decode the bitmask semantics to identify why the type triggered a non-stable classification.

Compose stability inference faces limitations with recursive structures and value classes because they trigger edge cases in the 12-phase algorithm. These types often result in Unknown or Combined classifications, requiring manual annotations or runtime checks to resolve.