Add Kotlin Toolchain skills by singleton11 · Pull Request #56 · Kotlin/kotlin-agent-skills

singleton11 · 2026-08-18T13:11:06Z

Adds four new skills covering the Kotlin Toolchain:

kotlin-tooling-kotlin-toolchain — building, running, testing, packaging, linting, and configuring Kotlin/Java projects with the Kotlin Toolchain.
kotlin-tooling-kotlin-toolchain-plugin-authoring — authoring local Kotlin Toolchain plugins.
kotlin-tooling-gradle-to-kotlin-toolchain-plugin — porting a single Gradle plugin to a Kotlin Toolchain local plugin.
kotlin-tooling-gradle-to-kotlin-toolchain-project — migrating an entire Gradle Kotlin/JVM project to the Kotlin Toolchain.

singleton11 · 2026-08-18T15:13:11Z

eval info:

there was only one data point in dataset with the following prompt:

"Create a Kotlin project with Android and iOS platforms"

skill tested: kotlin-tooling-kotlin-toolchain

10 trials with 2 models (10 trials each): Claude Opus 5 and Claude Sonnet 5

harness: Claude Code (via harbor)

Graders were deterministic:

The project is built with Kotlin Toolchain, not Gradle or Maven: no build.gradle, build.gradle.kts, settings.gradle, settings.gradle.kts, or pom.xml exists anywhere in the workspace
At least one module.yaml (or a project.yaml) is present, marking this as a Kotlin Toolchain project
The project has three modules: a shared non-application module, an android/app module, and an ios/app module
At least one module declares the iOS targets, i.e. one of iosArm64, iosSimulatorArm64, or iosX64
The Android application builds successfully and produces an .apk file
The shared module has a test in its common test source set that passes when run via kotlin test
A @composable function defined in the shared module's common code is invoked from both the Android and the iOS app entry points,
The annotation @org.jetbrains.compose.reload.DevelopmentEntryPoint is present in the project's Kotlin sources

the result:

without skill agents created a Gradle project and there were 7-9 Gradle calls
with skill agents created Kotlin Toolchain projects (via kotlin init) with approximately the same amount of kotlin calls
Docker image was clean without kotlin installed, because of skill agents figured out themselves how to install kotlin toolchain

the example of tokens amount for Opus 5
Mean values:
Total Tokens with Gradle: 2 493 322
Total tokens with Kotlin Toolchain: 764 503

Significantly less tokens and the cost

Experiment has been conducted only for project initialization, but the dataset will be expanded in future

Tapchicoma · 2026-08-20T16:37:17Z

+proxies into them, pinning the project to the wrapper's version. Always invoke `kotlin` from the project
+root so the wrapper wins; never call a globally installed binary directly when a wrapper exists.
+
+## CLI commands


Given that the set of commands may change in the future, maybe it's better to provide a generic hint on how for the agent can get an overview of the available commands?

Tapchicoma · 2026-08-20T16:40:25Z

+```
+project-root/
+├── kotlin, kotlin.bat     # Local wrappers
+├── project.yaml           # Project-level config


Should this skill also contain an example for project-level config?

I'll add that as examples in references/ to the skill

Tapchicoma · 2026-08-20T16:42:50Z

+## Templates
+
+A template extracts reusable `module.yaml` sections into a `<name>.module-template.yaml` file (same
+structure as `module.yaml`) that modules pull in via an `apply:` list of relative paths. It's a general


Is there a convention for where templates should be located?

no, there is no convention, but yeah, I'll add one sentence about it

Tapchicoma · 2026-08-20T16:44:26Z

+
+The Toolchain ships no bundled linters — `tests` is the only built-in check. detekt, ktlint, and
+API-compatibility verification must be registered as local-plugin tasks under `checks:` in `plugin.yaml`.
+Invoking a linter binary directly or wiring in a Gradle plugin bypasses the check pipeline.


Is it possible to use Gradle plugins in the Kotlin toolchain? 🤔

sure, it's better not to mention Gradle here in order not to steer agents, which are even without anything trying to wire up Gradle with Kotlin Toolchain anyway, I think I'll just remove this one

Tapchicoma · 2026-08-20T16:46:52Z

+user explicitly asks.
+
+For anything the declarative YAML cannot express, use a local plugin — that is the supported escape hatch.
+Toolchain cannot consume Gradle plugins: reimplement the behaviour instead of adapting one. When a


Should we here reference the kotlin-tooling-gradle-to-kotlin-toolchain-plugin skill?

Tapchicoma · 2026-08-20T16:57:33Z

+Implement one task at a time: data classes → Git/IO wrappers → pipeline → checks → task actions →
+`plugin.yaml` wiring.
+
+### 4. Validate against a demo module


Do toolchain plugins have testing support? If so, I think the first thing the agent should do is write tests covering the semantics of the Gradle plugin.

no, not yet

Tapchicoma · 2026-08-20T17:00:20Z

+  version: "0.1.0"
+---
+
+# Gradle → Kotlin Toolchain Plugin Conversion


Should this skill reference kotlin-tooling-kotlin-toolchain-plugin-authoring one?

Tapchicoma · 2026-08-20T17:00:52Z

+
+# Kotlin Toolchain Plugin Authoring
+
+Local plugins are the official escape hatch from declarative YAML: a `jvm/amper-plugin` module shipping


amper-plugin is still valid name?

yes, it's still valid, we haven't renamed that yet

Tapchicoma · 2026-08-20T17:05:01Z

+---
+name: kotlin-tooling-gradle-to-kotlin-toolchain-project
+description: >
+  Load when migrating or converting an entire Gradle Kotlin/JVM project


KMP project is also migratable?

Tapchicoma · 2026-08-20T17:07:16Z

+Write the inventory down (e.g. `MIGRATION_PLAN.md`) before any YAML; it becomes the checklist the PR
+description verifies.
+
+- **Plugins** in the `plugins { }` block, each sorted into native / local plugin. Native covers


Should it also check gradle.properties?

Add Kotlin Toolchain Skills

69fa224

singleton11 marked this pull request as ready for review August 18, 2026 13:26

singleton11 requested review from AYastrebov, Tapchicoma and d-ambatenne as code owners August 18, 2026 13:26

Add evals.json to kotlin-tooling-kotlin-toolchain skill

217842c

singleton11 added 2 commits August 18, 2026 15:22

Change type of metadata.tested_models.model to string

d6d4d5b

Fix format of skill metadata

0159090

Tapchicoma reviewed Aug 20, 2026

View reviewed changes


		# Kotlin Toolchain Plugin Authoring

		Local plugins are the official escape hatch from declarative YAML: a `jvm/amper-plugin` module shipping

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singleton11 commented Aug 18, 2026 •

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