Agent skill

Kotlin Idioms

by irahardianto in irahardianto/awesome-agv

Kotlin coding idioms: compile-time null safety, data classes, sealed hierarchies, coroutines and Flow concurrency, and Kotest/MockK testing.

MITAuto-check passedMobile

Install Kotlin Idioms

skills CLI

$ npx skills add irahardianto/awesome-agv --skill kotlin-idioms -a claude-code

Project install by default; add -g for ~/.claude/skills/.

GitHub CLI

$ gh skill install irahardianto/awesome-agv kotlin-idioms --agent claude-code

Project scope by default; add --scope user for a personal install. Needs GitHub CLI 2.90.0 or later (public preview).

Manual copy

$ git clone --depth 1 https://github.com/irahardianto/awesome-agv.git skills-src && mkdir -p .claude/skills && cp -r skills-src/.agents/skills/kotlin-idioms .claude/skills/kotlin-idioms && rm -rf skills-src

Use ~/.claude/skills/ instead of .claude/skills for a personal install. The folder must contain SKILL.md.

Claude Code skills documentation · loads skills from .claude/skills/

Paste into Claude Code

Install the "kotlin-idioms" agent skill from https://github.com/irahardianto/awesome-agv/tree/main/.agents/skills/kotlin-idioms into .claude/skills/kotlin-idioms/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "kotlin-idioms", then confirm the skill loads.

Claude Code copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

$skill-installer

$skill-installer install https://github.com/irahardianto/awesome-agv/tree/main/.agents/skills/kotlin-idioms

Type this inside Codex. $skill-installer <name> installs a curated skill from openai/skills. The installer writes to $CODEX_HOME/skills (default ~/.codex/skills). Restart Codex if the skill does not show up.

skills CLI

$ npx skills add irahardianto/awesome-agv --skill kotlin-idioms -a codex

Project install goes to .agents/skills/; add -g for ~/.codex/skills/.

GitHub CLI

$ gh skill install irahardianto/awesome-agv kotlin-idioms --agent codex

Project scope by default (.agents/skills/); add --scope user for a personal install.

Manual copy

$ git clone --depth 1 https://github.com/irahardianto/awesome-agv.git skills-src && mkdir -p .agents/skills && cp -r skills-src/.agents/skills/kotlin-idioms .agents/skills/kotlin-idioms && rm -rf skills-src

Use ~/.agents/skills/ instead of .agents/skills for a personal install.

Codex skills documentation · loads skills from .agents/skills/

Paste into Codex

Install the "kotlin-idioms" agent skill from https://github.com/irahardianto/awesome-agv/tree/main/.agents/skills/kotlin-idioms into .agents/skills/kotlin-idioms/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "kotlin-idioms", then confirm the skill loads.

Codex copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

skills CLI

$ npx skills add irahardianto/awesome-agv --skill kotlin-idioms -a cursor

Project install goes to .agents/skills/; add -g for ~/.cursor/skills/.

GitHub CLI

$ gh skill install irahardianto/awesome-agv kotlin-idioms --agent cursor

Project scope by default (.agents/skills/); add --scope user for a personal install.

Manual copy

$ git clone --depth 1 https://github.com/irahardianto/awesome-agv.git skills-src && mkdir -p .cursor/skills && cp -r skills-src/.agents/skills/kotlin-idioms .cursor/skills/kotlin-idioms && rm -rf skills-src

Use ~/.cursor/skills/ instead of .cursor/skills for a personal install.

Cursor skills documentation · loads skills from .cursor/skills/, .agents/skills/, .claude/skills/, .codex/skills/

Paste into Cursor

Install the "kotlin-idioms" agent skill from https://github.com/irahardianto/awesome-agv/tree/main/.agents/skills/kotlin-idioms into .cursor/skills/kotlin-idioms/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "kotlin-idioms", then confirm the skill loads.

Cursor copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

gemini skills install

$ gemini skills install https://github.com/irahardianto/awesome-agv.git --path .agents/skills/kotlin-idioms

--scope user (default) or --scope workspace; --path is the subfolder of the repo that holds the skill; --consent skips the security confirmation prompt.

skills CLI

$ npx skills add irahardianto/awesome-agv --skill kotlin-idioms -a gemini-cli

Project install goes to .agents/skills/; add -g for ~/.gemini/skills/.

GitHub CLI

$ gh skill install irahardianto/awesome-agv kotlin-idioms --agent gemini-cli

Project scope by default (.agents/skills/); add --scope user for a personal install.

Manual copy

$ git clone --depth 1 https://github.com/irahardianto/awesome-agv.git skills-src && mkdir -p .gemini/skills && cp -r skills-src/.agents/skills/kotlin-idioms .gemini/skills/kotlin-idioms && rm -rf skills-src

Use ~/.gemini/skills/ instead of .gemini/skills for a personal install, then run /skills reload.

Gemini CLI skills documentation · loads skills from .gemini/skills/, .agents/skills/

Paste into Gemini CLI

Install the "kotlin-idioms" agent skill from https://github.com/irahardianto/awesome-agv/tree/main/.agents/skills/kotlin-idioms into .gemini/skills/kotlin-idioms/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "kotlin-idioms", then confirm the skill loads.

Gemini CLI copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

GitHub CLI

$ gh skill install irahardianto/awesome-agv kotlin-idioms

Installs for Copilot at project scope by default; add --scope user for a personal install. Preview a skill first with gh skill preview. Needs GitHub CLI 2.90.0 or later (public preview).

skills CLI

$ npx skills add irahardianto/awesome-agv --skill kotlin-idioms -a github-copilot

Project install goes to .agents/skills/; add -g for ~/.copilot/skills/.

Manual copy

$ git clone --depth 1 https://github.com/irahardianto/awesome-agv.git skills-src && mkdir -p .github/skills && cp -r skills-src/.agents/skills/kotlin-idioms .github/skills/kotlin-idioms && rm -rf skills-src

Use ~/.copilot/skills/ instead of .github/skills for a personal install. Commit .github/skills so cloud agent and code review can use it.

GitHub Copilot skills documentation · loads skills from .github/skills/, .claude/skills/, .agents/skills/

Paste into GitHub Copilot

Install the "kotlin-idioms" agent skill from https://github.com/irahardianto/awesome-agv/tree/main/.agents/skills/kotlin-idioms into .github/skills/kotlin-idioms/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "kotlin-idioms", then confirm the skill loads.

GitHub Copilot copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

skills CLI

$ npx skills add irahardianto/awesome-agv --skill kotlin-idioms -a opencode

OpenCode documents no install command of its own. Project install goes to .agents/skills/; add -g for ~/.config/opencode/skills/.

GitHub CLI

$ gh skill install irahardianto/awesome-agv kotlin-idioms --agent opencode

Project scope by default (.agents/skills/); add --scope user for a personal install.

Manual copy

$ git clone --depth 1 https://github.com/irahardianto/awesome-agv.git skills-src && mkdir -p .opencode/skills && cp -r skills-src/.agents/skills/kotlin-idioms .opencode/skills/kotlin-idioms && rm -rf skills-src

Use ~/.config/opencode/skills/ instead of .opencode/skills for a personal install.

OpenCode skills documentation · loads skills from .opencode/skills/, .claude/skills/, .agents/skills/

Paste into OpenCode

Install the "kotlin-idioms" agent skill from https://github.com/irahardianto/awesome-agv/tree/main/.agents/skills/kotlin-idioms into .opencode/skills/kotlin-idioms/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "kotlin-idioms", then confirm the skill loads.

OpenCode copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

Facts

Skill name: kotlin-idioms
GitHub stars: 156
Token cost: ~732 tokens
SKILL.md length: 163 words
Files: 1
Skills in repo: 34
Repo updated: Oct 5, 2026
First seen: Oct 7, 2026
Licence: MIT

At a glance

Kotlin coding idioms: compile-time null safety, data classes, sealed hierarchies, coroutines and Flow concurrency, and Kotest/MockK testing.

Works in 3 steps: ? for nullable types — never platform… → Prefer ?.let {} and ?: (Elvis) over null… → Never !! in production — use…
Reviewing Kotlin backend
Instructions only: no scripts, shell commands, URLs or credentials in SKILL.md
Multiplatform code

What it does

Kotlin Idioms is an agent skill from irahardianto/awesome-agv. Kotlin coding idioms: compile-time null safety, data classes, sealed hierarchies, coroutines and Flow concurrency, and Kotest/MockK testing. Use when developing, refactoring, or reviewing Kotlin backend, Android, or multiplatform code.

Its SKILL.md is about 730 tokens, which your agent loads only when the skill is triggered. It is a single SKILL.md file with no bundled scripts.

It sits in Mobile, covering Android development. It works with Kotlin and Android. The repository describes itself as: Comprehensive sets of standards and practices designed to elevate the capabilities of AI coding agents. The licence is MIT.

When your agent uses it

Reviewing Kotlin backend
Multiplatform code

Example prompts

“/kotlin-idioms”

Workflow steps

3 steps, taken from the first numbered list in SKILL.md.

? for nullable types — never platform types without annotation
Prefer ?.let {} and ?: (Elvis) over null checks.
Never !! in production — use requireNotNull with a message.

What it can do on your machine

Read from SKILL.md and the folder at commit 9e997ba. It shows what the files ask for, not the result of running them.

Tool permissions
Pre-approves nothing: there is no allowed-tools line, so your agent's usual permission prompts apply.
From allowed-tools in the SKILL.md frontmatter.
Runs code
No scripts in the folder and no shell commands in SKILL.md (its code samples are kotlin).
From the folder's file list and the shell code blocks in SKILL.md.
Network
No URLs in SKILL.md.
From URLs in SKILL.md, links to its own repository left out.
Credentials
Names no API keys, tokens, secrets or passwords.
From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.

Context cost

Kotlin Idioms loads about 732 tokens when it runs. Until then it costs about 62 tokens; SKILL.md has 163 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it: ~62
When it runs · the whole SKILL.md, loaded when a task matches: ~732

Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.

Safety

Auto-check passed

The automated check found no risky patterns in SKILL.md.

Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); files beside SKILL.md are not scanned.

SKILL.md

The full file from irahardianto/awesome-agv at commit 9e997ba, republished under its MIT licence (© irahardianto). 163 words, ~732 tokens.

Download SKILL.mdSave it as .claude/skills/kotlin-idioms/SKILL.md (or your agent's skills folder).

name: kotlin-idioms
description: Kotlin coding idioms: compile-time null safety, data classes, sealed hierarchies, coroutines and Flow concurrency, and Kotest/MockK testing. Use when developing, refactoring, or reviewing Kotlin backend, Android, or multiplatform code.

Kotlin Idioms and Patterns

Kotlin rewards conciseness, null safety, and coroutine-based concurrency. Idiomatic Kotlin = safe, expressive, interop-aware.

Scope: Kotlin coding idioms. Test naming: .agents/rules/testing-strategy.md.

Null Safety

? for nullable types — never platform types without annotation:

kotlin

fun findById(id: String): Task?  // explicitly nullable
fun getById(id: String): Task    // guaranteed non-null — throws if not found

Prefer ?.let {} and ?: (Elvis) over null checks.
Never !! in production — use requireNotNull with a message.

Data Classes and Sealed Types

data class for DTOs and domain objects:

kotlin

data class CreateTaskRequest(val title: String, val priority: Priority)

sealed class/sealed interface for restricted hierarchies:

kotlin

sealed interface TaskResult {
    data class Success(val task: Task) : TaskResult
    data class NotFound(val id: String) : TaskResult
    data class ValidationError(val errors: List<String>) : TaskResult
}

Exhaustive when with sealed types:

kotlin

when (result) {
    is TaskResult.Success -> ok(result.task)
    is TaskResult.NotFound -> notFound(result.id)
    is TaskResult.ValidationError -> badRequest(result.errors)
}

Coroutines

Structured concurrency — coroutineScope, supervisorScope.
Never GlobalScope.launch — always scoped.

Flow for reactive streams:

kotlin

fun observeTasks(): Flow<List<Task>> = flow {
    while (currentCoroutineContext().isActive) {
        emit(storage.getAll())
        delay(5.seconds)
    }
}

Naming

PascalCase for classes. camelCase for functions, properties.
No get/set prefixes — use properties.
Backtick function names only in tests: `should create task when valid`()

Testing

kotest or JUnit 5 + MockK:

kotlin

@Test
fun `create task returns task when valid`() {
    val result = service.create("Test", Priority.HIGH)
    assertThat(result.title).isEqualTo("Test")
}

Formatting and Static Analysis

Tool	Purpose	Command
`ktlint`	Formatting	`ktlint --format`
`detekt`	Static analysis	`detekt --config detekt.yml`
Kotlin compiler	Null safety	Built-in

Code Idioms and Conventions .agents/rules/code-idioms-and-conventions.md
Testing Strategy .agents/rules/testing-strategy.md
Error Handling Principles .agents/rules/error-handling-principles.md

Files

Just SKILL.md in .agents/skills/kotlin-idioms of irahardianto/awesome-agv.

Open the folder on GitHubat commit 9e997ba

Compare with similar skills

Kotlin Idioms next to the 5 skills that share the most tags, products or categories with it. Stars are the repository's; “used in” counts other GitHub owners with a copy.

Kotlin Idioms compared with similar skills
Skill	Stars	Used in	Tokens	Auto-check	Licence	Repo updated
Kotlin Idioms this skillirahardianto/awesome-agv	156	—	~732	Automated safety check: Pass	MIT	6 days ago
Android Hidden API and R8 Checkgkd-kit/gkd	43k	—	~1.5k	Automated safety check: Pass	GPL-3.0	today
Compose Multiplatform Patternsmonta-app/ocpp-emulator	180	5 repos	~2k	Automated safety check: Pass	Apache-2.0	yesterday
Android Developmentdpconde/claude-android-skill	336	—	~1.7k	Automated safety check: Pass	MIT	10 mo ago
Architecture Overclocknekomangaorg/Neko	2.8k	—	~1.4k	Automated safety check: Pass	Apache-2.0	yesterday
Claude Android NinjaDrjacky/claude-android-ninja	124	—	~5.2k	Automated safety check: Pass	Apache-2.0	12 days ago

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Questions about Kotlin Idioms

What does Kotlin Idioms do?

Kotlin coding idioms: compile-time null safety, data classes, sealed hierarchies, coroutines and Flow concurrency, and Kotest/MockK testing. Kotlin Idioms is an agent skill from irahardianto/awesome-agv. Kotlin coding idioms: compile-time null safety, data classes, sealed hierarchies, coroutines and Flow concurrency, and Kotest/MockK testing.

When should I use Kotlin Idioms?

Kotlin Idioms fits situations like: reviewing Kotlin backend; multiplatform code.

How do I install Kotlin Idioms in Claude Code?

Run `npx skills add irahardianto/awesome-agv --skill kotlin-idioms -a claude-code`. Or copy the skill folder (.agents/skills/kotlin-idioms in irahardianto/awesome-agv) into .claude/skills/kotlin-idioms in your project. Claude Code loads it when a task matches its description.

How do I install Kotlin Idioms in Codex?

Run `npx skills add irahardianto/awesome-agv --skill kotlin-idioms -a codex`. Or copy the skill folder (.agents/skills/kotlin-idioms in irahardianto/awesome-agv) into .agents/skills/kotlin-idioms in your project. Codex loads it when a task matches its description.

Can I use Kotlin Idioms in Cursor, Gemini CLI or GitHub Copilot?

Cursor, Gemini CLI, GitHub Copilot and OpenCode also load SKILL.md folders. With the skills CLI, run `npx skills add irahardianto/awesome-agv --skill kotlin-idioms -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/kotlin-idioms, .gemini/skills/kotlin-idioms, .github/skills/kotlin-idioms and .opencode/skills/kotlin-idioms in your project.

What does Kotlin Idioms need to run?

SKILL.md names no scripts, command-line tools or credentials: Kotlin Idioms is instructions for the agent only.

Does Kotlin Idioms access the network?

SKILL.md contains no URLs. Any network use would come from the scripts or tools the agent runs. This is read from the text; nothing was executed.

Is Kotlin Idioms safe to install?

Our automated static check of SKILL.md found no risky patterns, such as piping downloads into a shell, reading credential files or hidden Unicode. It is not a guarantee. Review the folder before installing.

What licence does Kotlin Idioms use?

Kotlin Idioms is published under the MIT licence (the repository's licence). It allows redistribution, so the full SKILL.md is shown on this page.

How many tokens does Kotlin Idioms use?

About 732 tokens (SKILL.md is roughly 2.9k characters). Agents keep only the skill's name and description in context until a task matches; then they load SKILL.md in full.

What are the alternatives to Kotlin Idioms?

Skills that share tags, products or a category with Kotlin Idioms: Android Hidden API and R8 Check (gkd-kit/gkd, 43k stars), Compose Multiplatform Patterns (monta-app/ocpp-emulator, 180 stars), Android Development (dpconde/claude-android-skill, 336 stars) and Architecture Overclock (nekomangaorg/Neko, 2.8k stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.

Who maintains Kotlin Idioms?

irahardianto (a GitHub user) maintains it in irahardianto/awesome-agv, which has 156 GitHub stars. The repository holds 34 skills in this directory. The repository was last updated on October 5, 2026.

Source: irahardianto/awesome-agv on GitHub. Facts on this page come from the repository at the commit we read; the author's words are quoted as theirs.

Kotlin Idioms

Install Kotlin Idioms

Facts

At a glance

What it does

When your agent uses it

Example prompts

Workflow steps

What it can do on your machine

Tool permissions

Runs code

Network

Credentials

Context cost

Safety

SKILL.md

Kotlin Idioms and Patterns

Null Safety

Data Classes and Sealed Types

Coroutines

Naming

Testing

Formatting and Static Analysis

Files

Compare with similar skills

Similar skills

Android Hidden API and R8 Check

Compose Multiplatform Patterns

Android Development

Architecture Overclock

Claude Android Ninja

Expo Brownfield Integration

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Questions about Kotlin Idioms

Install Kotlin Idioms

Facts

At a glance

What it does

When your agent uses it

Example prompts

Workflow steps

What it can do on your machine

Tool permissions

Runs code

Network

Credentials

Context cost

Safety

SKILL.md

Kotlin Idioms and Patterns

Null Safety

Data Classes and Sealed Types

Coroutines

Naming

Testing

Formatting and Static Analysis

Related

Files

Compare with similar skills

Similar skills

More from irahardianto/awesome-agv

Related

Questions about Kotlin Idioms