Problem Statement

EAS Build workers don't include tsx in their environment, but Expo's official documentation recommends using tsx/cjs for TypeScript configuration files. This creates an inconsistent developer experience where following official best practices requires manual workarounds.

Current Official Documentation

Expo docs explicitly recommend using tsx/cjs at the top of app.config.ts:

import "tsx/cjs";

import type { ConfigContext, ExpoConfig } from "expo/config";

// ... rest of config

The Issue

When EAS Build attempts to evaluate app.config.ts, it fails with:

Cannot find module 'tsx/cjs'

This occurs because:

• @expo/config uses sucrase internally for TypeScript compilation

• User config files import tsx/cjs following official documentation

• EAS Build workers don't have tsx pre-installed

• Build fails before reaching dependency installation phase

Current Workaround Required

Developers must add a pre-install hook to their package.json:

"scripts": {

"eas-build-pre-install": "npm install -g tsx@4.20.5"

}

Use Case Details

• Project Type: React Native + Expo SDK 54 app

• TypeScript Config: Complex app.config.ts with multiple imports and conditional logic

• Following Best Practices: Using recommended tsx/cjs import per official docs

• Build Environment: EAS Build with development profile

• Package Manager: Bun (but affects all package managers)

Why This Should Be Included

• Documentation Consistency: Workers should support what the docs recommend

• Zero-Config Experience: Developers shouldn't need workarounds for documented patterns

• Common Use Case: Most TypeScript projects use tsx for config files

• Small Footprint: tsx is a lightweight addition to worker environment

• Industry Standard: tsx is the de-facto tool for running TypeScript in Node.js

Proposed Solution

Pre-install tsx in EAS Build worker environments alongside other essential tools like Node.js, npm/yarn, etc.

Impact: Eliminates need for workarounds and ensures seamless experience when following official Expo TypeScript documentation.

Environment

• Expo SDK: 54.0.6

• EAS CLI: 16.19.3

• React Native: 0.81.4

• TypeScript: 5.9.2

• Package Manager: Bun 1.2.22