pnpm run build fails on Windows with spawnSync npm ENOENT

[knqiufan]

What happened?

pnpm run build fails on Windows while bundling @step-harness/coding-agent. TypeScript compilation and copy-assets finish, then scripts/build-coding-agent-bundle.mjs exits with spawnSync npm ENOENT.

Environment: Windows 10 (10.0.26200), Node.js v24.14.1, pnpm 9.15.9, package @step-harness/coding-agent@0.84.4 at commit 8297eb5.

node:internal/child_process:1119
    result.error = new ErrnoException(result.error, 'spawnSync ' + options.file);
                   ^

Error: spawnSync npm ENOENT
  code: 'ENOENT',
  syscall: 'spawnSync npm',
  path: 'npm',
  spawnargs: [
    '--prefix',
    'D:\\code\\git-project\\Step-Code\\apps\\cli',
    'run',
    'build'
  ]
}

The stack points at execFileSync("npm", ["--prefix", appEntryDir, "run", "build"], ...) in scripts/build-coding-agent-bundle.mjs.

Earlier npm run build steps in the same pnpm run build succeed, because pnpm launches them through cmd.exe /c. execFileSync does not use a shell and does not search PATHEXT, so it looks for a file named npm. On Windows the executable is npm.cmd.

Steps to reproduce

1. Clone the repo on Windows and run pnpm install --ignore-scripts.
2. Run pnpm run build from the repository root.

Expected behavior

pnpm run build completes, including the CLI compile started by the coding-agent bundle script.

[xuxujo97-coder]

This comment was generated by AI during triage.

Verification (against current main)

• Likely root cause: scripts/build-coding-agent-bundle.mjs:181 runs execFileSync("npm", ["--prefix", ..., "run", "build"]). On Windows npm is npm.cmd, and execFileSync without shell: true cannot spawn .cmd shims — the ENOENT you hit. (Your trace prints it via spawnSync; same mechanism.)

Fix would be shell: true (with argument quoting) or resolving npm.cmd on win32. Maintainers will pick the shape.