fix(install): make npm install -g packages reachable on PATH

[xxxigm]

What does this PR do?

Fixes "I can npm i -g <pkg> but the package isn't usable on the command line" after a quick install — reported by a user whose globally-installed npm binaries were not on PATH.

Root cause

When the installer can't find a suitable system Node, it installs a bundled Node into $HERMES_HOME/node/ and symlinks only node, npm, npx into the command link dir (~/.local/bin, /usr/local/bin, or $PREFIX/bin), which it ensures is on PATH.

But the bundled Node's npm uses its default global prefix, which is the Node install dir:

$ npm prefix -g
/home/user/.hermes/node

So npm install -g <pkg> drops the package binary in $HERMES_HOME/node/bin/<pkg> — a directory that is not on PATH (only the link dir is). The user's global binaries are therefore unreachable even though npm i -g succeeds. Worse, $HERMES_HOME/node is rm -rf'd and re-extracted on every Node upgrade, so those globals are also wiped.

Reproduced on a real Hermes-managed install:

$ command -v node            # ~/.local/bin/node (symlink, on PATH)
$ npm prefix -g              # ~/.hermes/node   ← globals land in ~/.hermes/node/bin (OFF PATH)

The fix

Redirect the bundled Node's npm global prefix to the command link dir's parent, so global bins land in the link dir itself — already on PATH, alongside node/npm/npx, and surviving Node upgrades:

printf 'prefix=%s\n' "$(dirname "$node_link_dir")" > "$HERMES_HOME/node/etc/npmrc"

• ~/.local/bin user install → prefix ~/.local → bins in ~/.local/bin ✅
• root FHS install → prefix /usr/local → bins in /usr/local/bin ✅
• Termux → prefix $PREFIX → bins in $PREFIX/bin ✅

It's written to the bundled Node's prefix-local global npmrc ($HERMES_HOME/node/etc/npmrc, npm's default globalconfig for that Node), so it is scoped to the Hermes-managed Node only — the user's other Node installs and their ~/.npmrc are untouched. Hermes's own global install (agent-browser) passes an explicit --prefix "$HERMES_HOME/node" (CLI overrides config) and is unaffected.

Verified end-to-end against a real bundled Node: with the redirect, npm prefix -g returns ~/.local and ~/.local/bin is confirmed on PATH.

The same fix is applied to both bundled-install paths: scripts/install.sh (install_node) and scripts/lib/node-bootstrap.sh (_nb_install_bundled_node).

Type of Change

• 🐛 Bug fix (non-breaking change that fixes an issue)

Changes Made

• scripts/install.sh: after symlinking node/npm/npx, write prefix=<link-dir parent> to $HERMES_HOME/node/etc/npmrc.
• scripts/lib/node-bootstrap.sh: same redirect in the bundled-Node fallback.
• tests/test_install_sh_node_global_prefix.py: assert both scripts perform the redirect.

How to Test

scripts/run_tests.sh tests/test_install_sh_node_global_prefix.py
# Manual: on a bundled-Node install, `npm i -g cowsay && cowsay hi` now works.

[teknium1]

Reviewed and verified end-to-end — this is a clean fix for a real bug.

Premise confirmed. On the bundled-Node fallback, npm's default global prefix is the Node dir, so npm install -g <pkg> drops binaries in $HERMES_HOME/node/bin — off PATH (only the command link dir is) and wiped on every Node upgrade. Reproduced the reported "I can npm i -g but the command isn't found" symptom.

Mechanism is correct and well-scoped. Writing prefix= to $HERMES_HOME/node/etc/npmrc lands in npm's per-Node global config, so the override applies only to the Hermes-managed Node — the user's nvm/system Node and their ~/.npmrc are untouched. Confirmed npm honors prefix= from the global npmrc. The redirect targets the link dir's parent (~/.local), so global bins resolve to ~/.local/bin alongside the node/npm/npx symlinks already on PATH, and survive Node upgrades since they live outside node/bin. Matches the manual workaround given to the reporter exactly.

Idempotent / repairs existing installs. The no-op guard ([ -x "$HERMES_HOME/node/bin/npm" ] || return 0) plus calling it from check_node / ensure_node means re-running the installer fixes pre-existing managed installs, not just fresh ones.

Validation:

• npm prefix=-from-global-npmrc behavior verified locally.
• The 3 regression tests pass.
• CI fully green (6 test shards + amd64/arm64 builds + nix + e2e + attribution).

No issues found. Plan: salvage onto current main (58 commits behind, install-scripts only — no conflict), rebase-merge to preserve @xxxigm's authorship.

cc @expede @ethernet8023