windows-npm-run-script-shelllisted

# Windows Npm Run Script Shell ## Overview Windows npm scripts need a shell. If `ComSpec` is missing or npm cannot infer a script shell, `npm run ...` can fail inside npm before `tsc`, Vite, Vitest, or Playwright actually runs. ## Triage Use this flow before changing app code: 1. Run the target tool directly with `npx`, for example `npx tsc -b --pretty false`, `npx vite build`, or `npx vitest run`. 2. Run `npm run <script> --loglevel verbose`. 3. Open the npm debug log if output is empty. 4. Check shell config: ```powershell npm config get script-shell npm config get cache npm config get update-notifier Write-Host "ComSpec=[$env:ComSpec]" Write-Host "SHELL=[$env:SHELL]" ``` If direct `npx` commands pass but `npm run` fails with `ERR_INVALID_ARG_TYPE: The "file" argument must be of type string. Received undefined`, treat it as npm shell configuration, not a project build failure. If direct `node <script>` succeeds but `npm test`/`npm run` exits silently in a sandbox, rerun with `--loglevel verbose`. When npm reports `EPERM` creating `%LocalAppData%\npm-cache\_logs` or attempts registry access only for update checks, treat it as npm runtime side effects, not a test failure. ## Fix Prefer a project-local `.npmrc` so the fix travels with the repo: ```ini script-shell=C:\Windows\System32\cmd.exe ``` For sandboxed Windows workspaces where npm cannot write the user cache/log directory, keep npm side effects inside the repo and disable network-prone notices: ```ini cache