An architectural study of different approaches to transforming objects into bytes. We analyze four fundamental approaches based on benchmarks: reflective automation of Serializable, manual control of Externalizable, platform optimization of Parcelable, and universal code generation of kotlinx.serialization. We explore not only how these mechanisms work, but why they were created this way, what trade-offs are embedded in their architecture, and how they perform in different environments, from server JVM to mobile Android to cross-platform Kotlin.

A deep dive into the philosophical foundation of testing in Kotlin: the meaning behind expect/actual, differences between Unit and JUnit tests, and the conceptual roles of mocks, stubs, fakes, and spies. Understanding tests not as scripts, but as controlled simulations of reality.

In this article, we dive deep inside Decompose and Essenty: how they save state without using ViewModel and onSaveInstanceState, what happens at the StateKeeper and InstanceKeeper level, how all this relates to Android SavedStateRegistry and serialization through kotlinx.serialization. A detailed, step-by-step analysis of the entire chain : from components to low-level details.

A comprehensive article about how Android saves and restores state: from onSaveInstanceState and Bundle to modern architecture with SavedStateHandle and SavedStateRegistry. How everything is connected to the lifecycle of Activity, Fragment, and ViewModel, what roles ActivityThread, Instrumentation, and ActivityClientRecord play. A complete low-level data flow that demystifies all the magic moments.

What happens under the hood when we call viewModel() in Compose or View? How does ViewModelStoreOwner lookup work, what does LocalViewModelStoreOwner do, how does Compose connect to the View hierarchy, and how are DI delegates like hiltViewModel() and koinViewModel() structured? A deep technical look at the scoping and state mechanism.

How fragments manage their ViewModelStore, what FragmentManagerViewModel is, why child fragments are needed, and why Retain fragments are considered deprecated. A complete breakdown of architectural connections and call chains that allow fragments to preserve state during recreation.

What actually happens to ViewModel when Activity is destroyed and recreated? We break down the entire chain: ViewModelStore, NonConfigurationInstances, ActivityThread, and ActivityClientRecord. We show in detail where and how state is stored, and how Android magically restores everything during configuration changes.