Agent skill

Dart Modern Features

Guidelines for using modern Dart features (v3.0 - v3.10) such as Records, Extension Types, Class Modifiers, Wildcards, Digit Separators, Null-Aware Elements, and Dot Shorthands.

Apache-2.0Auto-check passedMobile

Install Dart Modern Features

skills CLI

$ npx skills add kevmoo/dash_skills --skill dart-modern-features -a claude-code

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

GitHub CLI

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

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 kevmoo/dash_skills --skill dart-modern-features -a codex

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

GitHub CLI

$ gh skill install kevmoo/dash_skills dart-modern-features --agent codex

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

Manual copy

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

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

GitHub CLI

$ gh skill install kevmoo/dash_skills dart-modern-features --agent cursor

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

Manual copy

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

--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 kevmoo/dash_skills --skill dart-modern-features -a gemini-cli

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

GitHub CLI

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

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 kevmoo/dash_skills --skill dart-modern-features -a github-copilot

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

Manual copy

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

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

Manual copy

$ git clone --depth 1 https://github.com/kevmoo/dash_skills.git skills-src && mkdir -p .opencode/skills && cp -r skills-src/skills/dart-modern-features .opencode/skills/dart-modern-features && 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 "dart-modern-features" agent skill from https://github.com/kevmoo/dash_skills/tree/main/skills/dart-modern-features into .opencode/skills/dart-modern-features/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "dart-modern-features", 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: dart-modern-features
GitHub stars: 147
Token cost: ~1.6k tokens
SKILL.md length: 592 words
Files: 2
Skills in repo: 12
Repo updated: Oct 8, 2026
First seen: Oct 7, 2026
Licence: Apache-2.0

At a glance

Guidelines for using modern Dart features (v3.0 - v3.10) such as Records, Extension Types, Class Modifiers, Wildcards, Digit Separators, Null-Aware Elements, and Dot Shorthands.

Works in 2 steps: When to use this skill → Features
Tasks that involve Cross-platform mobile apps
SKILL.md covers 1. When to use this skill, Discovery, 2. Features and Related Skills
Instructions only: no scripts, shell commands, URLs or credentials in SKILL.md

What it does

Dart Modern Features is an agent skill from kevmoo/dash_skills. Guidelines for using modern Dart features (v3.0 - v3.10) such as Records, Extension Types, Class Modifiers, Wildcards, Digit Separators, Null-Aware Elements, and Dot Shorthands.

Its SKILL.md is about 1.6k tokens, which your agent loads only when the skill is triggered. The skill folder holds 2 other files (for example `evals/evals.json`).

It sits in Mobile, covering Cross-platform mobile apps. It works with Dart. The repository describes itself as: Agent Skills for Dart and Flutter ecosytem. The licence is Apache-2.0.

When your agent uses it

Tasks that involve Cross-platform mobile apps

Example prompts

“Use the dart-modern-features skill to guideline for using modern Dart features (v3.0 - v3.10) such as Records, Extension Types, Class Modifiers…”
“/dart-modern-features”

Workflow steps

2 steps, taken from the step headings in SKILL.md.

When to use this skill
Features

What it can do on your machine

Read from SKILL.md and the folder at commit 397a703. 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 dart).
From the folder's file list and the shell code blocks in SKILL.md.
Network
Links to these hosts (documentation or services it may open):
- github.com
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

Dart Modern Features loads about 1.6k tokens when it runs. Until then it costs about 50 tokens; SKILL.md has 592 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it: ~50
When it runs · the whole SKILL.md, loaded when a task matches: ~1.6k

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 kevmoo/dash_skills at commit 397a703, republished under its Apache-2.0 licence (© kevmoo). 592 words, ~1,614 tokens.

Download SKILL.mdSave it as .claude/skills/dart-modern-features/SKILL.md (or your agent's skills folder). This skill also uses 1 other file; get the full folder from GitHub.

name: dart-modern-features
description: Guidelines for using modern Dart features (v3.0 - v3.10) such as Records, Extension Types, Class Modifiers, Wildcards, Digit Separators, Null-Aware Elements, and Dot Shorthands.
key_features: Records & Extension Types, Class Modifiers & Wildcards, Null-aware elements & Dot shorthands

Dart Modern Features

1. When to use this skill

Use this skill when:

Writing or reviewing Dart code targeting Dart 3.0 or later.
Refactoring legacy Dart code to use modern, concise, and zero-cost features such as records, extension types, class modifiers, null-aware collection elements, dot shorthands, and digit separators.
Looking for idiomatic ways to handle multiple return values or zero-cost domain wrappers.

For pattern matching, switch expressions, and list/map/split destructuring, use dart-use-pattern-matching. For converting closed class hierarchies into exhaustive sealed types, use dart-seal-type-hierarchies.

When NOT to use (Abstention Guardrails)

Do NOT apply modern features or refactor code when:

SDK Constraint < 3.0.0: The package's pubspec.yaml specifies an SDK constraint that supports Dart 2.x (e.g., sdk: '>=2.19.0 <4.0.0'). Refactoring to Dart 3 features will introduce syntax errors for Dart 2 users.
Public API Records with > 3 Fields: Records work well for 2–3 return values or internal tuples, but complex public API payloads are clearer and more extensible as dedicated classes or extension types.

Discovery

To find candidates for modernization:

Null-Aware Elements

Search for collection if statements checking for null:

Regex: if\s*$\w+\s*!=\s*null$\s*\w+

Digit Separators

Search for long numbers without separators:

Regex: \b\d{6,}\b (Matches numbers with 6 or more digits).

2. Features

Records

Use records as anonymous, immutable, aggregate structures to bundle multiple objects without defining a custom class. Prefer them for returning multiple values from a function or grouping related data temporarily.

Avoid: Creating a dedicated class for simple multiple-value returns.

dart

class UserResult {
  final String name;
  final int age;
  UserResult(this.name, this.age);
}

UserResult fetchUser() {
  return UserResult('Alice', 42);
}

Prefer: Using records to bundle types seamlessly on the fly.

dart

(String, int) fetchUser() {
  return ('Alice', 42);
}

void main() {
  var user = fetchUser();
  print(user.$1); // Alice
}

Class Modifiers

Use class modifiers (final, base, interface, sealed) to restrict how classes can be subtyped outside their defining library:

interface class: External libraries may implement, but cannot extend.
base class: External libraries may extend, but cannot implement (preserving private implementation invariants).
final class: External libraries can neither extend nor implement.
sealed class: Closed family of subtypes within the same library enabling exhaustive switching (see dart-seal-type-hierarchies).

Avoid: Leaving internal implementation classes open to arbitrary external subclassing or interface implementation when invariants must be enforced.

dart

class TokenStore {
  void save(String token) {}
}

Prefer: Declaring explicit subtyping capabilities with class modifiers.

dart

final class TokenStore {
  void save(String token) {}
}

Show full SKILL.md (252 more words)Show less

Extension Types

Use extension types for a zero-cost wrapper around an existing type. Use them to restrict operations or add custom behavior without runtime overhead.

Avoid: Allocating new wrapper objects just for domain-specific logic or type safety.

dart

class Id {
  final int value;
  Id(this.value);
  bool get isValid => value > 0;
}

Prefer: Using extension types which compile down to the underlying type at runtime.

dart

extension type Id(int value) {
  bool get isValid => value > 0;
}

Digit Separators

Use underscores (_) in number literals strictly to improve visual readability of large numeric values.

Avoid: Long number literals that are difficult to read at a glance.

dart

const int oneMillion = 1000000;

Prefer: Using underscores to separate thousands or other groupings.

dart

const int oneMillion = 1_000_000;

Wildcard Variables

Use wildcards (_) as non-binding variables or parameters to explicitly signal that a value is intentionally unused.

Avoid: Inventing clunky, distinct variable names to avoid "unused variable" warnings.

dart

void handleEvent(String ignoredName, int status) {
  print('Status: $status');
}

Prefer: Explicitly dropping the binding with an underscore.

dart

void handleEvent(String _, int status) {
  print('Status: $status');
}

Null-Aware Elements

Use null-aware elements (?) inside collection literals to conditionally include items only if they evaluate to a non-null value.

Avoid: Using collection if statements for simple null checks.

dart

var names = [
  'Alice',
  if (optionalName != null) optionalName,
  'Charlie'
];

Prefer: Using the ? prefix inline.

dart

var names = ['Alice', ?optionalName, 'Charlie'];

Dot Shorthands

Use dot shorthands to omit the explicit type name when it can be confidently inferred from context, such as with enums or static fields.

Avoid: Fully qualifying type names when the type is obvious from the context.

dart

LogLevel currentLevel = LogLevel.info;

Prefer: Reducing visual noise with inferred shorthand.

dart

LogLevel currentLevel = .info;

dart-use-pattern-matching: Authoritative guide for Dart 3 pattern matching, switch expressions, and list/map/String.split() destructuring.
dart-seal-type-hierarchies: Converting closed class hierarchies into sealed types for exhaustive switching.
dart-best-practices: General code style and foundational Dart idioms that predate or complement the modern syntax features.

Files

SKILL.md and 1 other file in skills/dart-modern-features of kevmoo/dash_skills.

SKILL.md
evals/evals.json

Open the folder on GitHubat commit 397a703

Compare with similar skills

Dart Modern Features 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.

Dart Modern Features compared with similar skills
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Fjson Dart Bean GeneratorK3vinb5/unyo-app	664	—	~2.2k	Automated safety check: Pass	BSD-3-Clause	3 mo ago
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BlocVeryGoodOpenSource/vgv-ai-flutter-plugin	170	—	~2k	Automated safety check: Pass	MIT	3 days ago
Flutter Dart Code Reviewaffaan-m/ECC	276k	2 repos	~5.8k	Automated safety check: Notes	MIT	today
Signals for Flutterrodydavis/signals.dart	819	—	~1.9k	Automated safety check: Pass	Apache-2.0	26 days ago

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Questions about Dart Modern Features

What does Dart Modern Features do?

Guidelines for using modern Dart features (v3.0 - v3.10) such as Records, Extension Types, Class Modifiers, Wildcards, Digit Separators, Null-Aware Elements, and Dot Shorthands. Dart Modern Features is an agent skill from kevmoo/dash_skills.10) such as Records, Extension Types, Class Modifiers, Wildcards, Digit Separators, Null-Aware Elements, and Dot Shorthands.

When should I use Dart Modern Features?

Dart Modern Features fits situations like: tasks that involve Cross-platform mobile apps.

How do I install Dart Modern Features in Claude Code?

Run `npx skills add kevmoo/dash_skills --skill dart-modern-features -a claude-code`. Or copy the skill folder (skills/dart-modern-features in kevmoo/dash_skills) into .claude/skills/dart-modern-features in your project. Claude Code loads it when a task matches its description.

How do I install Dart Modern Features in Codex?

Run `npx skills add kevmoo/dash_skills --skill dart-modern-features -a codex`. Or copy the skill folder (skills/dart-modern-features in kevmoo/dash_skills) into .agents/skills/dart-modern-features in your project. Codex loads it when a task matches its description.

Can I use Dart Modern Features 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 kevmoo/dash_skills --skill dart-modern-features -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/dart-modern-features, .gemini/skills/dart-modern-features, .github/skills/dart-modern-features and .opencode/skills/dart-modern-features in your project.

What does Dart Modern Features need to run?

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

Does Dart Modern Features access the network?

SKILL.md names 1 domain. As links in the text: github.com. This is read from the text; nothing was executed.

Is Dart Modern Features 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 Dart Modern Features use?

Dart Modern Features 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 Dart Modern Features use?

About 1.6k tokens (SKILL.md is roughly 6.5k 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 Dart Modern Features?

Skills that share tags, products or a category with Dart Modern Features: Fjson Dart Bean Generator (K3vinb5/unyo-app, 664 stars), Flutter Riverpod State Management (andrewyng/context-hub, 14k stars), Bloc (VeryGoodOpenSource/vgv-ai-flutter-plugin, 170 stars) and Flutter Dart Code Review (affaan-m/ECC, 276k stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.

Who maintains Dart Modern Features?

kevmoo (a GitHub user) maintains it in kevmoo/dash_skills, which has 147 GitHub stars. The repository holds 12 skills in this directory. The repository was last updated on October 8, 2026.

Source: kevmoo/dash_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 Dart Modern Features

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

Dart Modern Features

1. When to use this skill

When NOT to use (Abstention Guardrails)

Discovery

Null-Aware Elements

Digit Separators

2. Features

Records

Class Modifiers

Extension Types

Digit Separators

Wildcard Variables

Null-Aware Elements

Dot Shorthands

Related Skills

Files

Compare with similar skills

Similar skills

More from kevmoo/dash_skills

Related

Questions about Dart Modern Features