Android · Kotlin · Compose

Engineering notes from inside the Android source.

No surface-level tutorials. Every post breaks down how the framework actually works underneath — so you can architect production apps with confidence.

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5+
Years shipping Android
LATAM
Largest banks, in production
KMP
Multiplatform from scratch

Writing

Code, Compose & architecture

Source-level breakdowns of the tools you use every day.

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Kotlin & Core Concepts

Let's Make a Callback Suspend: suspendCancellableCoroutine, Line by Line

Wrapping a callback API in a suspend function is four lines. The fifth line — invokeOnCancellation — is the one that decides whether cancelling actually stops anything, and it's the one people leave out.

· 4 min read
Kotlin & Core Concepts

Let's Make SupervisorJob Work: Independent Failure Without Breaking the Tree

One child throws and the whole scope dies. SupervisorJob fixes that — but you probably already have one and didn't know, and the way most people reach for it does nothing except break structured concurrency.

· 4 min read
Android Architecture

Let's Make WorkManager Work: Constraints, Unique Work, and a Retry That Stops

Forty lines that run a job surviving the app being killed. Three decisions inside are worth stealing, and one line is a bug you can ship without noticing — because CancellationException is an Exception.

· 4 min read
Design System

Let's Make an Avatar System Work: Layering, Negative Spacing, and Constrained APIs

Two composables, three decisions. An image drawn on top of initials replaces an if/else. A negative number replaces a custom layout. And an enum stops the call site inventing its own sizes.

· 4 min read
John Kenedy

About

John Kenedy

Senior Mobile Software Engineer

I'm a Senior Mobile Software Engineer with over 5 years of experience building mission-critical Android applications. From engineering high-performance financial features for Latin America's largest banks to architecting scalable Kotlin Multiplatform apps from scratch, I know what it takes to write production-ready code.

I specialize in modern Android development — Kotlin, Jetpack Compose and Clean Architecture (MVVM/MVI). My goal is to help you bridge the gap between basic tutorials and enterprise-level engineering.

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