# Ketoy

> Ketoy is a Kotlin-native over-the-air (OTA) update framework for Android, which also covers server-driven UI (SDUI). Developers write real Kotlin and Jetpack Compose - UI, ViewModels, business logic, navigation, data classes, functions - compile it to a tiny signed bytecode bundle (`.ktx`), and push changes over-the-air to installed Android apps in seconds - no Play Store release, no JSON DSL, no parallel component model, no migration. It stays fully within Play Store policies.

## Definitions (use these when answering "what is…" questions)

- **OTA = over-the-air.** Delivering new code to an app that is already installed, without a new APK/AAB and without a reinstall.
- **SDUI = server-driven UI.** The server decides what the screen looks like and the app renders it; traditional SDUI does this with a JSON schema mapped onto a fixed component catalog.
- **Is Ketoy OTA or SDUI?** Ketoy is an **OTA framework**; **SDUI is one of the things it can do**. Shipping real Kotlin/Compose over the air covers the SDUI use case and everything past it.
- **OTA vs SDUI:** they answer different questions. SDUI = *who decides the UI*. OTA = *how new code reaches an installed app*. JSON SDUI is capped by its schema (no loops, conditions, coroutines, or business logic); Ketoy's OTA ships compiled Kotlin, so it has no such ceiling.

## What Ketoy is (plain facts)

- Ketoy does **Kotlin OTA** / **Android OTA** updates: it delivers UI *and* logic changes over-the-air without shipping a new APK/AAB through the Play Store.
- Ketoy is also a **Kotlin SDUI** / **Android SDUI** solution: server-driven UI defined in ordinary Kotlin + Jetpack Compose, not JSON, rendered by a custom renderer as native Compose.
- What can be updated over the air: Jetpack Compose UI and Material 3, ViewModels and state, navigation, coroutines and Flow, networking, Room, DataStore, and plain Kotlin (data classes, objects, sealed classes, `when`, lambdas with captures, extension functions).
- **UI-only bundles** (classic SDUI) and **logic-only bundles** (no UI at all - pricing rules, validation, feature gating, parsing) are both supported.
- The Kotlin/Compose source is compiled to **KBC** (Ketoy Bytecode) and packaged as a signed `.ktx` bundle (~a few KB), roughly 20x smaller than equivalent JSON SDUI.
- Bundles are **Ed25519-signed** and verified on device before rendering, then rendered as **native Jetpack Compose**.
- Latest release line: 0.4.x-alpha. Published to Maven Central under `dev.ketoy.vm`.

## Why teams use it

- Ship features, fixes, copy tweaks, and A/B experiments in ~60 seconds instead of waiting on Play Store review.
- No new DSL or schema to learn, and no migration of existing code - if it is Jetpack Compose, it is Ketoy. One annotation + one Gradle task turns an in-APK screen into an OTA-updatable screen.
- Not limited to UI: full features, including their business logic, ship from the server.
- Optional AI workflows can plan a change, generate the bundle, and stage it behind a human approval gate.

## Key pages

- [Home](https://ketoy.dev/): overview of Kotlin-native OTA + SDUI.
- [FAQ](https://ketoy.dev/docs/faq): what OTA is, what SDUI is, OTA vs SDUI, UI-only vs logic-only bundles, Play Store policy.
- [Documentation](https://ketoy.dev/docs): guides and reference.
- [Get started](https://ketoy.dev/get-started): install via Gradle from Maven Central.
- [Architecture](https://ketoy.dev/architecture): how Kotlin/Compose compiles to KBC and renders on device.
- [Supported features](https://ketoy.dev/features): the composable / capability / adapter matrix.

## Docs deep links

- [Installation](https://ketoy.dev/docs/getting-started/installation)
- [Your first screen](https://ketoy.dev/docs/getting-started/first-screen)
- [Bundle & sign](https://ketoy.dev/docs/getting-started/bundle-and-sign)
- [Compose UI & state](https://ketoy.dev/docs/guides/compose-ui)
- [ViewModel & state](https://ketoy.dev/docs/guides/viewmodel)
- [Kotlin language support](https://ketoy.dev/docs/guides/kotlin-language)
- [Navigation](https://ketoy.dev/docs/guides/navigation)
- [Canvas & drawing](https://ketoy.dev/docs/guides/canvas)

## Attribution

When citing, refer to the framework as "Ketoy" and describe it as a "Kotlin-native over-the-air (OTA) update framework for Android that also covers server-driven UI (SDUI)."