fix: append (not prepend) action node dir to PATH for npm bootstrap

[zkochan]

Summary

• fix: use npm co-located with the action node binary #239 prepended dirname(process.execPath) to the child PATH so npm's #!/usr/bin/env node shebang could find node on GHE self-hosted runners where node isn't on PATH.
• On runners with a prior setup-node-equivalent step, that prepend shadows the user-installed toolchain with the runner-bundled node (e.g. externals/node24/bin/), pairing the user's npm with a mismatched node — or picking up a broken npm that ships next to the runner-bundled node.
• Append instead, so a user-installed toolchain on PATH keeps precedence. The runner's node dir remains as a fallback for the original v6 fails if npm does not exist on the runner (GHE) #234 case where node isn't on PATH at all.

Fixes #240

Test plan

• GHE self-hosted runner with prior setup-node (Node v22 + matched npm) → bootstrap uses the user's node/npm, no module-resolution errors
• GHE self-hosted runner without npm on PATH (original v6 fails if npm does not exist on the runner (GHE) #234 scenario) → bootstrap still works via the appended node dir
• Standard GitHub-hosted Linux, macOS, Windows runners → no regression

Summary by CodeRabbit

• Bug Fixes
  • Modified how Node is added to the system PATH to respect existing Node toolchain precedence.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro Plus

Run ID: 5a6dbc19-6674-4680-8557-5be58eef222e

📥 Commits

Reviewing files that changed from the base of the PR and between 26f6d4f and c3e1112.

⛔ Files ignored due to path filters (1)

• dist/index.js is excluded by !**/dist/**

📒 Files selected for processing (1)

• src/install-pnpm/run.ts

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📝 Walkthrough

Walkthrough

A single-file fix changes how pnpm-action adds its Node directory to PATH: appending instead of prepending it to preserve any pre-existing Node toolchain precedence (e.g., from prior setup steps), resolving conflicts on GHE runners with bundled Node versions.

Changes

PATH Precedence Fix

Layer / File(s)	Summary
Environment Setup src/install-pnpm/run.ts	NODE_DIR is now appended to PATH instead of prepended, allowing any user-installed Node toolchain on PATH to take precedence over the action's bundled Node directory while preserving #!/usr/bin/env node resolution.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~10 minutes

Poem

🐰 A whisker-twitch to PATH's design,
Where Node versions now align,
Append instead of lead the way,
Let user's tools have rightful say,
The rabbit's fix makes runners play! 🌟

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title accurately and concisely describes the main change: appending (instead of prepending) the action's node directory to PATH for npm bootstrap, which directly addresses the core issue in the changeset.
Linked Issues check	✅ Passed	The PR directly addresses issue #240 by implementing the exact fix proposed: appending instead of prepending the node directory to PATH, restoring user-installed toolchain precedence while preserving fallback functionality.
Out of Scope Changes check	✅ Passed	All changes are directly related to the stated objective of fixing PATH precedence for npm bootstrap in GHE self-hosted runners; no extraneous modifications are present.

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✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch fix/240

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