Pumpkin Plugin API for Kotlin

This repository builds the Kotlin bindings for Pumpkin plugins using WebAssembly (Wasm) components.

The api Gradle module is a publishable Kotlin/WASI library and generated-source snapshot. It generates the WIT bindings only while API maintainers build or publish the library; the consumer Gradle plugin will unpack that snapshot before compiling a plugin, so plugin authors do not install or run wit-bindgen.

The root component template remains available while the consumer Gradle plugin is being moved into gradle-plugin.

API maintainer requirements

Kotlin/Wasm + components it's still in it's early stages, and not as straightforward as could be. You will need to have several things installed for everything to work.

• JDK 17 or later
  • To run Gradle 9.4
• Rust
  • This is required only to build or publish the API, because wit-bindgen is built from a particular Kotlin-enabled fork.
  • You only need a default Rust install for your host platform. NOT for any WebAssembly targets

Building the API

Initialize the WIT submodule after cloning:

git submodule update --init --recursive

Publish a local development artifact with:

./gradlew :api:publishToMavenLocal

This generates the pumpkin package bindings under api/build/generated/, compiles them with the package-owned WIT export bridge, and publishes the KLIB plus a generated-source archive. The source archive includes the pinned WIT snapshot and Preview 1 reactor adapter needed to assemble a component.

repositories {
    mavenLocal()
    mavenCentral()
}

// The consumer Gradle plugin resolves the matching generated-source archive.

The API artifact exposes PumpkinPlugin and registerPlugin(...); plugin authors should implement and register that class rather than defining the generator-specific PluginRootFunctionsExportsImpl or MetadataImpl types.

Root template build

The original root template still builds a complete component with ./gradlew build. Gradle skips tool installation, binding generation, and component assembly when their declared inputs are unchanged. Use ./gradlew clean to remove generated build output; it intentionally retains the installed tool cache under tools/.

Updating the WIT

Keep an eye on github.com/Pumpkin-MC/pumpkin-plugin-wit

If you start getting errors like main ThreadId(01) pumpkin::plugin: Failed to load plugin from "./plugins\\my_plugin.wasm": Wasm plugin initialization error: plugin failed to load with error: component imports instance 'pumpkin:plugin/gui@0.1.0', but a matching implementation was not found in the linker or other "linker" errors when loading your plugin into Pumpkin, update the wit submodule

cd wit
git pull origin master
cd ..

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Attributions

This template was primarily derived from @jmrtsh's work on Kotlin/sample-wasi-http-kotlin, which is licensed under Apache-2.0