Fix pnpm Migration Phantom Dependency Errors

Migrating a Node.js project from package managers that use hoisted node_modules structures to strict content-addressable package managers often exposes hidden import assumptions that break continuous integration runners.

Quick solution:

pnpm add sharp

When a Node script fails with Error [ERR_MODULE_NOT_FOUND] for a package like sharp imported from scripts/medium-package.mjs after a clean continuous integration install, add the missing package to your manifest using pnpm add sharp for runtime dependencies or pnpm add -D sharp for build tools. Prerequisites include running a clean environment with a lockfile and running pnpm install --frozen-lockfile to ensure accurate dependency trees after committing updates.

Diagnosing Module Resolution Versus Build Failures

Traditional package managers often rely on node_modules layouts where dependencies of dependencies are hoisted to the root directory, allowing scripts or build tools to import packages without explicitly declaring them in the project manifest. When transitioning to pnpm, its strict symlinked and isolated structure removes this hoisting behavior. Undeclared imports that worked locally due to cached modules or ambient hoisting suddenly fail in clean continuous integration environments.

Symptom to Resolution Guide

Option	When to Use It	Trade-off or Failure Mode	Recommendation
pnpm add <package>	Runtime dependency is missing from the manifest	Increases direct dependency count	Explicitly declare all runtime packages in dependencies
pnpm add -D <package>	Build or script tool is missing from the manifest	Might bloat devDependencies if misused	Use for local build scripts and automation tasks
Frozen Lockfile Update	Pipeline throws lockfile mismatch errors	Requires committing workspace changes	Always commit lockfile updates before pushing to remote CI

Auditing and Fixing Missing Direct Imports

To prevent continuous integration failures, audit all custom scripts, build hooks, and automation tools located in directories like scripts or tools. Ensure every package imported via ES module syntax or CommonJS require statements is explicitly listed under dependencies or devDependencies in your project configuration file.

{
  "devDependencies": {
    "sharp": "*"
  }
}

After declaring the missing dependencies, update and commit the correct workspace lockfile, rerun a clean frozen install in a fresh checkout or clean workspace, and then rerun the exact failing script to verify that module resolution succeeds without relying on residual global state.

Verification and Execution Steps

• Run pnpm install --frozen-lockfile in a fresh checkout or clean workspace to simulate a clean installation and verify that the expected result is a successfully generated dependency tree without unexpected lockfile modifications.
• Locate the specific importing workspace or package manifest and verify that any required module is explicitly declared under dependencies or devDependencies.
• Execute the exact failing script locally using node scripts/medium-package.mjs to confirm that the previous module resolution error no longer occurs.
• Review continuous integration pipeline logs after pushing your updated lockfile and manifest changes to ensure artifact generation completes successfully.