Kotlin

Diagnoses and fixes slow Kotlin/Native compilation and linking in Kotlin Multiplatform projects that target iOS. Use when the user reports slow iOS or shared-framework builds, long linkDebug*/linkRelease* or XCFramework tasks, cold CI builds that re-download the Kotlin/Native toolchain, KSP or other generated code on the native path, transitiveExport usage, or asks for a local-development versus CI build performance plan.

Load when authoring, writing, or designing a Kotlin Toolchain local plugin to extend the declarative build with code generation, build-time processing, custom verification, or packaging that module.yaml cannot express, or when referencing @TaskAction, @Configurable, plugin.yaml, or jvm/amper-plugin. Skip for porting an existing Gradle plugin.

Load when building, running, testing, packaging, linting, or configuring a Kotlin/Java project with the Kotlin Toolchain (JetBrains' unified CLI, formerly Amper), when scaffolding a new or greenfield Kotlin project, or when the repo has project.yaml, module.yaml, or a ./kotlin wrapper. Skip for existing Gradle/Maven projects.

Use when converting Java source files to idiomatic Kotlin, when user mentions "java to kotlin", "j2k", "convert java", "migrate java to kotlin", or when working with .java files that need to become .kt files. Handles framework-aware conversion for Spring, Lombok, Hibernate, Jackson, Micronaut, Quarkus, Dagger/Hilt, RxJava, JUnit, Guice, Retrofit, and Mockito.

Migrate Kotlin (and Java) code from kotlinx.collections.immutable 0.3.x / 0.4.x to the latest 0.5.x. The 0.5.x line renames every copy-returning method on PersistentList / PersistentMap / PersistentSet / PersistentCollection to a participial form per KEEP-0459 (add→adding, removeAt→removingAt, set→replacingAt, put→putting, clear→cleared, …) and deprecates the old names (WARNING, with ReplaceWith). Driven by the compiler: bump the version, recompile, and apply the rename each deprecation warning names. Use when the user mentions kotlinx.collections.immutable 0.5.x, PersistentList migration, "Use adding() instead", KEEP-0459, or sees deprecation warnings from kotlinx.collections.immutable.

Load when migrating or converting an entire Gradle Kotlin project (build.gradle(.kts), wrapper, libs.versions.toml, buildSrc) to the Kotlin Toolchain, including rewriting CI and replacing Gradle plugins that have no native Toolchain equivalent. Skip for porting one Gradle plugin or general Toolchain work once Gradle is gone.

Load when porting, converting, or reimplementing a single Gradle plugin as a Kotlin Toolchain local plugin, or when mapping Gradle plugin concepts (Task, Extension, project.version, dependsOn, -P properties, afterEvaluate) to Toolchain analogs. Skip for migrating a whole Gradle project or authoring a plugin from scratch.

Migrate KMP projects from CocoaPods (kotlin("native.cocoapods")) to Swift Package Manager (swiftPMDependencies DSL) — replaces pod() with swiftPackage(), transforms cocoapods.* imports to swiftPMImport.*, and reconfigures the Xcode project.

Migrates Kotlin Multiplatform (KMP) projects to Android Gradle Plugin 9.0+. Handles plugin replacement (com.android.kotlin.multiplatform.library), module splitting, DSL migration, and the new default project structure. Use when upgrading AGP, when build fails due to KMP+AGP incompatibility, or when the user mentions AGP 9.0, android multiplatform plugin, KMP migration, or com.android.kotlin.multiplatform.library.

Model Kotlin persistence code correctly for Spring Data JPA and Hibernate. Covers entity design, identity and equality, uniqueness constraints, relationships, fetch plans, and common ORM (Object-Relational Mapping) traps specific to Kotlin. Use when creating or reviewing JPA (Java Persistence API) entities, diagnosing N+1 or LazyInitializationException, placing indexes and uniqueness rules, or preventing Kotlin-specific bugs such as data class entities and broken equals/hashCode.