expo-module

expo-module is a skill for Claude Code, Codex from emilyLi2020/WAVE. It costs 61 tokens per session (1,220 once invoked), scanned A, a copy of expo-module, Apache-2.0.

A guide for building Expo native modules and native views, which add Swift or Kotlin platform code that can be used from an Expo app. It also covers TypeScript definitions and project configuration.

In plain words
What is it for?
Use it to create or modify native modules and views, connect platform SDKs, add lifecycle behavior, configure automatic linking, or write configuration plugins.
Why use it?
It explains the platform-specific files and setup needed when an Expo app requires native functionality beyond its JavaScript code.

Skill for Claude CodeCodex

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add skills/emilyli2020/wave/expo-module
Any agent
npx skills add emilyLi2020/WAVE --skill expo-module
Clone the repo
git clone --depth 1 https://github.com/emilyLi2020/WAVE

Made for: Claude Code, Codex.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for expo-module

README.md
[![agentmods](https://agentmods.dev/badge/skills/emilyli2020/wave/expo-module.svg)](https://agentmods.dev/skills/emilyli2020/wave/expo-module)
Your own site
<a href="https://agentmods.dev/skills/emilyli2020/wave/expo-module"><img src="https://agentmods.dev/badge/skills/emilyli2020/wave/expo-module.svg" alt="Measured on agentmods" height="20"></a>
Per session 61 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,220 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin 80% copy Near-identical to another mod in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.00061 $0.01220
Opus 5 $0.00030 $0.00610
Sonnet 5 $0.00012 $0.00244
Haiku 4.5 $0.00006 $0.00122

Measured 4d ago against content hash 384c038bae02, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

expo-module scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 4d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

Origin

This is a copy

80% identical to expo-module — 16 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.

.agents/skills/expo-module/SKILL.md · 142 lines

How it starts

The opening of the file, as written. The whole thing — 142 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Writing Expo Modules

Complete reference for building native modules and views using the Expo Modules API. Covers Swift (iOS), Kotlin (Android), and TypeScript.

When to Use

  • Creating a new Expo native module or native view
  • Adding native functionality (camera, sensors, system APIs) to an Expo app
  • Wrapping platform SDKs for React Native consumption
  • Building config plugins that modify native project files
  • Adding Android, Apple, or web support to an existing Expo module
  • Editing expo-module.config.json, config plugins, or lifecycle hooks

References

Consult these resources as needed:

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

Quick Start

Prefer create-expo-module over manually creating native module files and directories. In practice, the best path is usually to create the scaffold first and then build on top of it. The scaffold sets up the expected layout, expo-module.config.json, podspec or Gradle files, TypeScript bindings, and the standalone example app flow.

If an existing Expo module only needs another platform, use create-expo-module add-platform-support instead of manually copying native directories.

See references/create-expo-module.md before scaffolding or extending a module. It covers:

  • local vs standalone modules
  • --platform, --features, --barrel, --package-manager, and non-interactive mode
  • expo.autolinking.nativeModulesDir
  • add-platform-support behavior and quirks

Read the full file on GitHub · 142 lines

Files

What ships with it

6 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 4d ago First seen · 142 lines · 61 tokens per session scan A 384c038bae02

Subscribe to this mod's changes

expo-module is a skill published in the GitHub repository emilyLi2020/WAVE (2 stars, last pushed 2mo ago), licensed Apache-2.0. It adds 61 tokens to every session and 1,220 once invoked, about $0.0003 per session on Opus 5. A static security scan graded it A with 0 findings. It is 80% identical to expo-module, differing in 16 lines, and is treated as a copy.

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