monorepo-predev-pattern

name: monorepo-predev-pattern description: "Description: Use when fixing "module not found" errors for @flightdeck/shared during development, or when setting up dev scripts in npm workspace monorepos."

Monorepo predev Script Pattern for Shared Packages

Description: Use when fixing "module not found" errors for @flightdeck/shared during development, or when setting up dev scripts in npm workspace monorepos.

The Problem

In this monorepo:

• packages/shared exports from dist/ (compiled TypeScript)
• packages/server dev script uses tsx watch which transpiles on-the-fly
• But tsx resolves @flightdeck/shared via the npm workspace symlink → packages/shared/dist/
• In a fresh environment, dist/ doesn't exist → ERR_MODULE_NOT_FOUND

The Solution

Add predev scripts that build shared before starting the dev server:

Root package.json:

{
  "scripts": {
    "predev": "npm run build:shared",
    "build:shared": "cd packages/shared && rm -f tsconfig.tsbuildinfo && npm run build",
    "dev": "node scripts/dev.mjs",
    "predev:server": "npm run build:shared"
  }
}

packages/server/package.json:

{
  "scripts": {
    "predev": "cd ../shared && rm -f tsconfig.tsbuildinfo && npm run build",
    "dev": "tsx watch src/index.ts"
  }
}

Key Details

• npm automatically runs predev before dev and predev:server before dev:server
• Always rm -f tsconfig.tsbuildinfo before building (see tsbuildinfo-cache-gotcha skill)
• From packages/server/, use cd ../shared && npm run build (not --workspace — that doesn't work from child dirs)
• --workspace=packages/shared only works from the monorepo root