Requirements

Kotlin compiler plugins operate on the compiler's intermediate representation, and those internals move between versions, so the supported range is narrow and specific.

Android and Desktop need Kotlin 2.3.x to 2.4.x. The iOS leg needs 2.3 or newer and prefers 2.4, because a Kotlin/Native library records an ABI version that an older compiler refuses outright. On Kotlin 2.2 and earlier the iOS leg goes inert and says so rather than failing later.

The iOS runtime is published once per Kotlin line and the plugin resolves the right coordinate from your Kotlin version. You do not select it. The Version Compatibility page carries the full plugin to Kotlin map.

The 2.x line targets Android Gradle Plugin 9.x and is built and tested against 9.2.1. The 1.x line targeted AGP 8.7.3, so a project still on AGP 8 should stay on 1.x until it upgrades.

Gradle 9.5.1 is the verified version, and it is what every sample in the repository runs. Configuration cache and configure on demand are both supported.

Hot reload runs on a device or emulator at API 28 or higher. Both physical devices and emulators are supported, with no restriction on manufacturer, chipset, or system image.

This is a requirement on the device you develop against, not on your project. The runtime library's own minSdk is 26, so adding HotSwan does not raise your project's minimum API level, and your release APK is unaffected.

Debug builds only. The reload path is a development tool and is not wired into release builds. Applying the plugin leaves your release configuration alone.

The reload target is iosSimulatorArm64, the iOS simulator on an Apple Silicon Mac. Compose Multiplatform 1.11.0 no longer publishes an iosX64 variant, so Apple Silicon is where this leg lives.

You need Compose Multiplatform 1.11.0, an Apple Silicon Mac, and Xcode with an installed iOS simulator runtime. Xcode 26.5 is the version the leg was built and measured on. Xcode 16 and other Xcode 26 builds are handled by the packaging path but have not been run end to end.

Two project level details matter. Your Info.plist needs CADisableMinimumFrameDurationOnPhone set to true, which is a standard Compose Multiplatform on iOS key. And your Compose entry point has to be a top level, zero argument function returning a UIViewController. An entry that takes arguments supplied from Swift is refused by name rather than reloaded incorrectly.

Applying the Gradle plugin is the rest of the setup. There is no Swift line to add and no extra dependency to declare. HotSwan does not declare or check an iOS deployment target.

Any Compose Desktop JVM target works. There is no variant concept on Desktop, so there is no debug requirement to satisfy.

Applying the Gradle plugin is the setup. The runtime self bootstraps the first time instrumented code runs, so a desktop app needs no extra line to become reloadable, and your running window shows up as a target you can select alongside your devices.

Calling installInterpreterBaselineDesktop() early in your main() is still recommended, because it starts the runtime at a point you choose rather than at the first composition. It is install if absent, so adding it to an app that has already self bootstrapped does nothing. The Kotlin Multiplatform page has the exact snippet.

This page is a summary, and it is more confident than the checks behind it. Most of these bounds are declared rather than enforced. There is no Gradle version check, no AGP version check, no Xcode version check and no host architecture check anywhere in the product.

In practice that means an unsupported combination fails with whatever error the underlying tool produces, not with a HotSwan message explaining the requirement. The exceptions are the two places where a wrong answer would be worse than an error: an unsupported Kotlin version on iOS, and an iOS entry point of the wrong shape. Both are refused by name.

If something does not behave the way this page describes, the Troubleshooting page is the next stop.