Agent skill

Kotlin Control Flow

A skill your agent uses when writing or reviewing Kotlin branching and control flow: when expressions, guard conditions, sealed type exhaustiveness, smart casts, nullable branching, early returns…

Apache-2.0Auto-check passedMobile

Install Kotlin Control Flow

skills CLI

$ npx skills add chrisbanes/skills --skill kotlin-control-flow -a claude-code

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

GitHub CLI

$ gh skill install chrisbanes/skills kotlin-control-flow --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/chrisbanes/skills.git skills-src && mkdir -p .claude/skills && cp -r skills-src/skills/kotlin-control-flow .claude/skills/kotlin-control-flow && 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-control-flow" agent skill from https://github.com/chrisbanes/skills/tree/main/skills/kotlin-control-flow into .claude/skills/kotlin-control-flow/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "kotlin-control-flow", 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/chrisbanes/skills/tree/main/skills/kotlin-control-flow

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 chrisbanes/skills --skill kotlin-control-flow -a codex

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

GitHub CLI

$ gh skill install chrisbanes/skills kotlin-control-flow --agent codex

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

Manual copy

$ git clone --depth 1 https://github.com/chrisbanes/skills.git skills-src && mkdir -p .agents/skills && cp -r skills-src/skills/kotlin-control-flow .agents/skills/kotlin-control-flow && 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-control-flow" agent skill from https://github.com/chrisbanes/skills/tree/main/skills/kotlin-control-flow into .agents/skills/kotlin-control-flow/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "kotlin-control-flow", 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 chrisbanes/skills --skill kotlin-control-flow -a cursor

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

GitHub CLI

$ gh skill install chrisbanes/skills kotlin-control-flow --agent cursor

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

Manual copy

$ git clone --depth 1 https://github.com/chrisbanes/skills.git skills-src && mkdir -p .cursor/skills && cp -r skills-src/skills/kotlin-control-flow .cursor/skills/kotlin-control-flow && 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-control-flow" agent skill from https://github.com/chrisbanes/skills/tree/main/skills/kotlin-control-flow into .cursor/skills/kotlin-control-flow/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "kotlin-control-flow", 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/chrisbanes/skills.git --path skills/kotlin-control-flow

--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 chrisbanes/skills --skill kotlin-control-flow -a gemini-cli

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

GitHub CLI

$ gh skill install chrisbanes/skills kotlin-control-flow --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/chrisbanes/skills.git skills-src && mkdir -p .gemini/skills && cp -r skills-src/skills/kotlin-control-flow .gemini/skills/kotlin-control-flow && 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-control-flow" agent skill from https://github.com/chrisbanes/skills/tree/main/skills/kotlin-control-flow into .gemini/skills/kotlin-control-flow/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "kotlin-control-flow", 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 chrisbanes/skills kotlin-control-flow

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 chrisbanes/skills --skill kotlin-control-flow -a github-copilot

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

Manual copy

$ git clone --depth 1 https://github.com/chrisbanes/skills.git skills-src && mkdir -p .github/skills && cp -r skills-src/skills/kotlin-control-flow .github/skills/kotlin-control-flow && 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-control-flow" agent skill from https://github.com/chrisbanes/skills/tree/main/skills/kotlin-control-flow into .github/skills/kotlin-control-flow/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "kotlin-control-flow", 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 chrisbanes/skills --skill kotlin-control-flow -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 chrisbanes/skills kotlin-control-flow --agent opencode

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

Manual copy

$ git clone --depth 1 https://github.com/chrisbanes/skills.git skills-src && mkdir -p .opencode/skills && cp -r skills-src/skills/kotlin-control-flow .opencode/skills/kotlin-control-flow && 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-control-flow" agent skill from https://github.com/chrisbanes/skills/tree/main/skills/kotlin-control-flow into .opencode/skills/kotlin-control-flow/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "kotlin-control-flow", 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-control-flow
GitHub stars: 1.1k
Token cost: ~1.2k tokens
SKILL.md length: 544 words
Files: 1
Skills in repo: 19
Repo updated: Oct 8, 2026
First seen: Oct 7, 2026
Licence: Apache-2.0

At a glance

A skill your agent uses when writing or reviewing Kotlin branching and control flow: when expressions, guard conditions, sealed type exhaustiveness, smart casts, nullable branching, early returns…

Works in 7 steps: Name the value being classified. If… → Choose the branch shape → Use a guard only on a subject when,… → …
Reviewing Kotlin branching and control flow: when expressions
SKILL.md covers Core principle, Procedure, Recipes and Related
Instructions only: no scripts, shell commands, URLs or credentials in SKILL.md

What it does

Kotlin Control Flow is an agent skill from chrisbanes/skills. Use when writing or reviewing Kotlin branching and control flow: when expressions, guard conditions, sealed type exhaustiveness, smart casts, nullable branching, early returns, or replacing complex if/else chains.

Its SKILL.md is about 1.2k 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. The repository describes itself as: Skills for Kotlin, Jetpack Compose, and Android development. The licence is Apache-2.0.

When your agent uses it

Reviewing Kotlin branching and control flow: when expressions
Guard conditions
Sealed type exhaustiveness
Nullable branching

Example prompts

“/kotlin-control-flow”

Workflow steps

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

Name the value being classified. If every branch tests it, use
Choose the branch shape
Use a guard only on a subject when, after a primary condition, when the
For a closed enum, Boolean, sealed type, or nullable closed type, name every
Use an early return only when it removes invalid or nullable state from the
Verify smart casts still work without as, !!, mutable temporaries, or
Compile and test. On failure, return to the smallest applicable earlier step

What it can do on your machine

Read from SKILL.md and the folder at commit 00bda52. 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 Control Flow loads about 1.2k tokens when it runs. Until then it costs about 58 tokens; SKILL.md has 544 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it: ~58
When it runs · the whole SKILL.md, loaded when a task matches: ~1.2k

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 chrisbanes/skills at commit 00bda52, republished under its Apache-2.0 licence (© chrisbanes). 544 words, ~1,165 tokens.

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

name: kotlin-control-flow
description: Use when writing or reviewing Kotlin branching and control flow: when expressions, guard conditions, sealed type exhaustiveness, smart casts, nullable branching, early returns, or replacing complex if/else chains.

Kotlin control flow

Core principle

Make the classified value obvious, keep branch-local predicates on their branch, and let the compiler prove closed-domain coverage.

Procedure

Name the value being classified. If every branch tests it, use when (subject); otherwise keep a subjectless when or if chain.

Choose the branch shape:

Code shape	Prefer
One classified value	`when (subject)`
Unrelated boolean conditions	Subjectless `when` or `if`/`else`
Primary case plus a branch-local predicate	Guard condition
Invalid input before the main path	Early return, `require`, or `check`
Closed value-returning domain	Exhaustive `when` expression
Open input or deliberate fallback	Explicit `else`

Use a guard only on a subject when, after a primary condition, when the extra predicate belongs to that branch and an unguarded branch still handles the primary condition. Put the guarded branch first. Split comma-separated conditions instead of guarding one of them.
For a closed enum, Boolean, sealed type, or nullable closed type, name every case and omit else. Match objects by value and class/data-class subtypes with is. When a data-bearing sealed case is collapsed by a catch-all, show the branch-level use in the review:
kotlin
```
is Outcome.Failed -> safeFailureLabel(outcome.reason)
```
The is check smart-casts outcome, so the branch can use reason without a cast. The helper name is illustrative; choose a safe mapping for the caller contract. Do not replace this branch-level explanation with a note that unspecified callers can inspect the original result. If the input is an open server/platform value or needs real fallback/logging, keep else.
Use an early return only when it removes invalid or nullable state from the main path. Keep nesting that expresses cleanup, transaction, or error handling.
Verify smart casts still work without as, !!, mutable temporaries, or duplicate casts. If they do not, keep the original shape or take a smaller refactor.
Compile and test. On failure, return to the smallest applicable earlier step or retain the prior shape. In a review of a closed sealed mapping, when a data-bearing subtype affects the mapping or its safe handling, put the typed branch and member access in the finding itself, not only in analysis or as a general note to add explicit cases. Use this pseudocode template with the actual subtype and payload member substituted:
kotlin
```
is <DataSubtype> -> map(result.<payload>)
```
This is a template, not literal Kotlin: the is test smart-casts result, and the member access shows how the branch uses its payload. If the public value stays generic, state how the branch handles the detail or why it is deliberately discarded. Naming cases alone or sending callers to inspect the original value is not complete branch guidance. Apply this only to closed, data-bearing cases; retain else for open-world values or real fallbacks. Finish when the subject, fallbacks, and relevant branch data are obvious to a reader and the resulting shape is easier to scan.

Show full SKILL.md (80 more words)Show less

Recipes

Use guarded branches to refine one case, rather than nesting an if:

kotlin

return when (event) {
    is Event.Message if event.isUnread -> Row.Highlighted(event.message)
    is Event.Message -> Row.Normal(event.message)
    Event.Empty -> Row.Empty
}

Use a subject when when repeated conditions classify one value, and include null as a branch when it is one case in a larger classification:

kotlin

return when (val selected = selection) {
    null -> SelectionUi.None
    is Selection.Single if selected.item.isArchived -> SelectionUi.Archived(selected.item)
    is Selection.Single -> SelectionUi.Active(selected.item)
    is Selection.Multiple -> SelectionUi.Count(selected.items.size)
}

Do not introduce guards on unsupported Kotlin versions, force unrelated boolean checks into a subject when, remove an open-world fallback, or flatten code that obscures cleanup, transactions, or errors.

Kotlin concurrency and Flow — state/event primitives.
Kotlin API design — explicit common-code branching.

Files

Just SKILL.md in skills/kotlin-control-flow of chrisbanes/skills.

Open the folder on GitHubat commit 00bda52

Compare with similar skills

Kotlin Control Flow 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 Control Flow compared with similar skills
Skill	Stars	Used in	Tokens	Auto-check	Licence	Repo updated
Kotlin Control Flow this skillchrisbanes/skills	1.1k	—	~1.2k	Automated safety check: Pass	Apache-2.0	yesterday
Compose Multiplatform Patternsmonta-app/ocpp-emulator	180	5 repos	~2k	Automated safety check: Pass	Apache-2.0	yesterday
Kotlin Patternsgetknit/knit	132	5 repos	~4.7k	Automated safety check: Pass	GPL-3.0	5 days ago
Summoncodeyousef/summon	167	—	~1.1k	Automated safety check: Pass	Apache-2.0	yesterday
Add JSON Schemayontrack/yontrack	102	—	~883	Automated safety check: Pass	MIT	today
Add Ktnip Parameter Strategyvendelieu/telegram-bot	249	—	~613	Automated safety check: Pass	Apache-2.0	5 days ago

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Works with

Kotlin

Questions about Kotlin Control Flow

What does Kotlin Control Flow do?

A skill your agent uses when writing or reviewing Kotlin branching and control flow: when expressions, guard conditions, sealed type exhaustiveness, smart casts, nullable branching, early returns…. Kotlin Control Flow is an agent skill from chrisbanes/skills. Use when writing or reviewing Kotlin branching and control flow: when expressions, guard conditions, sealed type exhaustiveness, smart casts, nullable branching, early returns, or replacing complex if/else chains.

When should I use Kotlin Control Flow?

Kotlin Control Flow fits situations like: reviewing Kotlin branching and control flow: when expressions; guard conditions; sealed type exhaustiveness; nullable branching.

How do I install Kotlin Control Flow in Claude Code?

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

How do I install Kotlin Control Flow in Codex?

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

Can I use Kotlin Control Flow 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 chrisbanes/skills --skill kotlin-control-flow -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-control-flow, .gemini/skills/kotlin-control-flow, .github/skills/kotlin-control-flow and .opencode/skills/kotlin-control-flow in your project.

What does Kotlin Control Flow need to run?

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

Does Kotlin Control Flow 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 Control Flow 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 Control Flow use?

Kotlin Control Flow is published under the Apache-2.0 licence (the repository's licence). It allows redistribution, so the full SKILL.md is shown on this page.

How many tokens does Kotlin Control Flow use?

About 1.2k tokens (SKILL.md is roughly 4.7k 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 Control Flow?

Skills that share tags, products or a category with Kotlin Control Flow: Compose Multiplatform Patterns (monta-app/ocpp-emulator, 180 stars), Kotlin Patterns (getknit/knit, 132 stars), Summon (codeyousef/summon, 167 stars) and Add JSON Schema (yontrack/yontrack, 102 stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.

Who maintains Kotlin Control Flow?

chrisbanes (a GitHub user) maintains it in chrisbanes/skills, which has 1,093 GitHub stars. The repository holds 19 skills in this directory. The repository was last updated on October 8, 2026.

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

Install Kotlin Control Flow

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 control flow

Core principle

Procedure

Recipes

Related

Files

Compare with similar skills

Similar skills

More from chrisbanes/skills

Related

Questions about Kotlin Control Flow