fix(nodejs plugin): rewrite setup-corepack as an ESM .mjs module

[mikeland73]

Summary

Fixes #2856.

The Corepack setup script introduced in #2845 (setup-corepack.js) is written in CommonJS and uses require(). The nodejs plugin runs it as the shell init_hook:

node "{{ .Virtenv }}/bin/setup-corepack.js"

When a project's root package.json sets "type": "module", Node treats every .js file in the directory tree — including this one inside .devbox/virtenv — as an ES module. The script then crashes on its first require(), taking the whole shell down:

ReferenceError: require is not defined in ES module scope, you can use import instead
This file is being treated as an ES module because it has a '.js' file extension
and '.../package.json' contains "type": "module".

As a result, devbox shell no longer starts for any nodejs project whose package.json declares "type": "module".

Fix

Rewrite the script as a native ES module and name it setup-corepack.mjs. The .mjs extension forces Node to treat the file as ESM regardless of the surrounding package.json type, so it works for both "type": "module" projects and default/CommonJS projects. (A plain .js ESM file would break the inverse case — Node parses .js as CommonJS when type is absent or commonjs.)

Changes:

• Rename plugins/nodejs/setup-corepack.js → plugins/nodejs/setup-corepack.mjs.
• require() → import for node:child_process and node:path.
• Read package.json via readFileSync + JSON.parse instead of require(), since JSON module import syntax differs across Node versions.
• Update the plugin's init_hook and create_files references in plugins/nodejs.json.
• Add a regression test case ("type": "module" in package.json) to testscripts/plugin/nodejs_corepack_autodetect.test.txt.

How was it tested?

• node --check on the .mjs file (valid ESM syntax).
• Ran the script directly in scratch dirs and confirmed it exits 0 (no crash, shell init never breaks) in all of:
  • package.json with {"type":"module"} — previously the reported ReferenceError.
  • default/CommonJS package.json.
  • package.json with a pinned packageManager (pnpm@9.0.0) — autodetect path activates correctly.
• Added Case 3 to the corepack autodetect testscript to guard against regression.

cc @AdaptivChris (issue reporter)

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Generated by Claude Code

[Copilot]

Pull request overview

This PR fixes a Node.js module-type edge case in the nodejs plugin: when a project’s root package.json sets "type": "module", Node treats setup-corepack.js under .devbox/virtenv/... as ESM and crashes on require(), breaking devbox shell. The fix renames the init hook script to .cjs so Node always executes it as CommonJS.

Changes:

• Renamed the Corepack init hook script to setup-corepack.cjs to avoid ESM interpretation under "type": "module".
• Updated plugins/nodejs.json to reference the new .cjs filename and bumped plugin version 0.0.3 → 0.0.4.
• Added a regression test case covering "type": "module" in package.json.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
plugins/nodejs/setup-corepack.cjs	Updates script header/docs to reflect .cjs usage so CommonJS require() remains valid under ESM projects.
plugins/nodejs.json	Points init_hook and create_files at setup-corepack.cjs and bumps plugin version.
testscripts/plugin/nodejs_corepack_autodetect.test.txt	Adds a regression case to ensure shells still start when package.json declares "type": "module".

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