Expo Module

What it does

When your agent uses it

• Modifying native modules for Expo
• Tasks that involve Cross-platform mobile apps
• Tasks that involve iOS development

Example prompts

• “/expo-module”

Requirements

• Node.js

Workflow steps

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

1. 1Choose the scaffold type first
2. 2Determine native expo-module features that you will need.
3. 3Scaffold deliberately
4. 4Replace generated example code with the real implementation.
5. 5If you add a new platform later, prefer add-platform-support over manual file copying.

What it can do on your machine

Read from SKILL.md and the folder at commit d4f4840. 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

  Shell commands in SKILL.md call:

  • npx

  From the folder's file list and the shell code blocks in SKILL.md.

• Network

  No URLs in SKILL.md. Its commands use npx, which can reach the network depending on how they are called.

  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

Expo Module loads about 1.6k tokens when it runs, and up to ~8.4k if it reads all its reference files. Until then it costs about 120 tokens; SKILL.md has 564 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it

~120

When it runs · the whole SKILL.md, loaded when a task matches

~1.6k

With references · SKILL.md plus every file in references/, read only if the agent opens them

~8.4k

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

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 expo/skills at commit d4f4840, republished under its MIT licence (© expo). 564 words, ~1,626 tokens.

name

expo-module

description

Guide for creating and writing Expo native modules and views using the Expo Modules API (Swift, Kotlin, TypeScript). Covers module definition DSL, native views, shared objects, config plugins, lifecycle hooks, autolinking, and type system. Use when building or modifying native modules for Expo. Not for migrating an existing Swift module from the definition DSL to the Expo Modules API 2.0 macros; use expo-migrate-module (from the expo-experiments plugin) for that.

version

1.0.0

license

MIT

references/
  create-expo-module.md      Scaffolding and add-platform-support workflow, defaults, and quirks
  native-module.md           Module definition DSL: Name, Function, AsyncFunction, Property, Constant, Events, type system, shared objects
  native-view.md             Native view components: View, Prop, EventDispatcher, view lifecycle, ref-based functions
  lifecycle.md               Lifecycle hooks: module, iOS app/AppDelegate, Android activity/application listeners
  config-plugin.md           Config plugins: modifying Info.plist, AndroidManifest.xml, reading values in native code
  module-config.md           expo-module.config.json fields, file placement, and autolinking behavior

import ExpoModulesCore

public class MyModule: Module {
  public func definition() -> ModuleDefinition {
    Name("MyModule")

    Function("hello") { (name: String) -> String in
      return "Hello \(name)!"
    }
  }
}

package expo.modules.mymodule

import expo.modules.kotlin.modules.Module
import expo.modules.kotlin.modules.ModuleDefinition

class MyModule : Module() {
  override fun definition() = ModuleDefinition {
    Name("MyModule")

    Function("hello") { name: String ->
      "Hello $name!"
    }
  }
}

import { requireNativeModule } from "expo";

const MyModule = requireNativeModule("MyModule");

export function hello(name: string): string {
  return MyModule.hello(name);
}

{
  "platforms": ["android", "apple"],
  "apple": {
    "modules": ["MyModule"]
  },
  "android": {
    "modules": ["expo.modules.mymodule.MyModule"]
  }
}

npx --yes submit-expo-feedback@latest --category skills --subject "expo-module" "<actionable feedback>"

© expo, MIT. Rendered from Markdown: HTML in the file is shown as text, images as links, and headings moved down two levels. Raw file

Files

SKILL.md and 7 other files (references) in plugins/expo/skills/expo-module of expo/skills.

• SKILL.md
• agents/openai.yaml
• references/config-plugin.md
• references/create-expo-module.md
• references/lifecycle.md
• references/module-config.md
• references/native-module.md
• references/native-view.md

Open the folder on GitHubat commit d4f4840

Used in 1 other repository

We found 1 copy of this SKILL.md (exact, near-identical or edited) in other folders, from 1 other GitHub owner. This page covers the copy in expo/skills, which our catalogue first saw on October 7, 2026.

• arcboxlabs/linkcode.agents/skills/expo-module