immutability Shipped
What this lens looks for
Mutable shared state eliminated as the root cause of concurrency bugs; let/val/const used by default; value types (structs, data classes) preferred over reference types; mutation contained behind clear boundaries (actors, StateFlow, useState)
What its verifier checks
No var/var declarations where let/val would suffice; mutable state confined to a single owner (actor, ViewModel, store); no shared mutable state across concurrent contexts; data classes or structs used for domain models