fix(install): repair existing managed-Node global prefix on re-run

The initial fix only wrote the prefix npmrc on a fresh Node install, so
pre-existing bundled-Node installs (Node already present) were not repaired
by re-running the installer — install_node/ensure_node skip when Node is
already up to date.

Extract the redirect into an idempotent helper
(configure_managed_node_npm_prefix / _nb_configure_npm_prefix) that no-ops
when there's no Hermes-managed npm, and call it unconditionally from
check_node (install.sh) and at the top of ensure_node (node-bootstrap.sh).
Re-running the install command now repairs an affected install in place,
not just brand-new ones.

scripts/install.sh

@@ -413,6 +413,25 @@ get_command_link_display_dir() {
     fi
 }
 
+# Point a Hermes-managed Node's `npm install -g` at a directory that is on
+# PATH. npm's default global prefix for a bundled Node is the Node dir itself,
+# so global package binaries land in $HERMES_HOME/node/bin — which is NOT on
+# PATH (only the command link dir is) and is wiped on every Node upgrade.
+# Redirecting the prefix to the link dir's parent makes global bins resolve to
+# the command link dir (node/npm/npx live there too, already on PATH) and
+# survive upgrades. Scoped to the managed Node via its prefix-local global
+# npmrc, so the user's other Node installs and their ~/.npmrc are untouched.
+# Hermes's own global installs pass an explicit --prefix and are unaffected.
+# Idempotent and a no-op when there is no Hermes-managed npm, so calling it on
+# every install run repairs pre-existing installs, not just fresh ones.
+configure_managed_node_npm_prefix() {
+    [ -x "$HERMES_HOME/node/bin/npm" ] || return 0
+    local link_dir
+    link_dir="$(get_command_link_dir)"
+    mkdir -p "$HERMES_HOME/node/etc"
+    printf 'prefix=%s\n' "$(dirname "$link_dir")" > "$HERMES_HOME/node/etc/npmrc"
+}
+
 get_hermes_command_path() {
     local link_dir
     link_dir="$(get_command_link_dir)"
@@ -722,6 +741,11 @@ node_satisfies_build() {
 check_node() {
     log_info "Checking Node.js (for browser tools)..."
 
+    # Repair pre-existing Hermes-managed installs where `npm install -g` lands
+    # off PATH. No-op when there's no managed Node, so this is safe to run on
+    # every install — including re-runs that skip the Node (re)install below.
+    configure_managed_node_npm_prefix
+
     if command -v node &> /dev/null && node_satisfies_build "$(node --version)"; then
         log_success "Node.js $(node --version) found"
         HAS_NODE=true
@@ -851,17 +875,7 @@ install_node() {
     ln -sf "$HERMES_HOME/node/bin/npm"  "$node_link_dir/npm"
     ln -sf "$HERMES_HOME/node/bin/npx"  "$node_link_dir/npx"
 
-    # Point this Node's `npm install -g` at a directory that is actually on
-    # PATH. By default npm's global prefix is the Node install dir, so user
-    # globals land in $HERMES_HOME/node/bin — which is NOT on PATH (only the
-    # link dir is) and is wiped on every Node upgrade. Redirecting the prefix
-    # to the link dir's parent makes global bins land in the link dir
-    # (node/npm/npx live there too, and it's already on PATH) and survive
-    # upgrades. Scoped to this Node via its prefix-local global npmrc, so the
-    # user's other Node installs and their ~/.npmrc are untouched. Hermes's
-    # own global installs pass an explicit --prefix and are unaffected.
-    mkdir -p "$HERMES_HOME/node/etc"
-    printf 'prefix=%s\n' "$(dirname "$node_link_dir")" > "$HERMES_HOME/node/etc/npmrc"
+    configure_managed_node_npm_prefix
 
     export PATH="$HERMES_HOME/node/bin:$PATH"
 

scripts/lib/node-bootstrap.sh

@@ -57,6 +57,19 @@ _nb_get_link_dir() {
     fi
 }
 
+# Redirect a Hermes-managed Node's `npm install -g` to the command link dir
+# (already on PATH) instead of the default $HERMES_HOME/node/bin, which is off
+# PATH and wiped on every Node upgrade. Scoped to the managed Node via its
+# prefix-local global npmrc; the user's other Node installs / ~/.npmrc are
+# untouched. Idempotent no-op when there's no managed npm.
+_nb_configure_npm_prefix() {
+    [ -x "$HERMES_HOME/node/bin/npm" ] || return 0
+    local _link_dir
+    _link_dir="$(_nb_get_link_dir)"
+    mkdir -p "$HERMES_HOME/node/etc"
+    printf 'prefix=%s\n' "$(dirname "$_link_dir")" > "$HERMES_HOME/node/etc/npmrc"
+}
+
 _nb_node_major() {
     local v
     v=$(node --version 2>/dev/null | sed 's/^v//' | cut -d. -f1)
@@ -207,12 +220,7 @@ _nb_install_bundled_node() {
     ln -sf "$HERMES_HOME/node/bin/npm"  "$_link_dir/npm"
     ln -sf "$HERMES_HOME/node/bin/npx"  "$_link_dir/npx"
 
-    # Redirect this Node's `npm install -g` to the link dir (already on PATH)
-    # instead of the default $HERMES_HOME/node/bin, which is off PATH and wiped
-    # on every Node upgrade. Scoped to this Node via its prefix-local global
-    # npmrc; the user's other Node installs / ~/.npmrc are untouched.
-    mkdir -p "$HERMES_HOME/node/etc"
-    printf 'prefix=%s\n' "$(dirname "$_link_dir")" > "$HERMES_HOME/node/etc/npmrc"
+    _nb_configure_npm_prefix
 
     export PATH="$HERMES_HOME/node/bin:$PATH"
 
@@ -228,6 +236,10 @@ _nb_install_bundled_node() {
 ensure_node() {
     HERMES_NODE_AVAILABLE=false
 
+    # Repair pre-existing managed installs where `npm install -g` lands off
+    # PATH. No-op when there's no managed Node, so it's safe to run first.
+    _nb_configure_npm_prefix
+
     if _nb_have_modern_node; then
         _nb_ok "Node $(node --version) found"
         HERMES_NODE_AVAILABLE=true

tests/test_install_sh_node_global_prefix.py

@@ -25,15 +25,31 @@ def test_install_sh_redirects_bundled_npm_global_prefix_to_link_dir() -> None:
     # The redirect must target the link dir's PARENT so global bins resolve to
     # <parent>/bin == the command link dir (node/npm/npx live there and it is
     # guaranteed on PATH by the installer's PATH setup).
-    assert 'printf \'prefix=%s\\n\' "$(dirname "$node_link_dir")" > "$HERMES_HOME/node/etc/npmrc"' in text
+    assert "configure_managed_node_npm_prefix()" in text
+    assert 'printf \'prefix=%s\\n\' "$(dirname "$link_dir")" > "$HERMES_HOME/node/etc/npmrc"' in text
 
-    # The npmrc lives under the bundled Node so it only affects this npm, not
-    # the user's other Node installs or their ~/.npmrc.
-    assert '"$HERMES_HOME/node/etc/npmrc"' in text
+
+def test_install_sh_repairs_existing_managed_node_on_rerun() -> None:
+    """The redirect must run on every install (not just fresh Node installs),
+    so re-running the installer repairs pre-existing managed installs whose
+    Node is already up to date and would otherwise skip install_node."""
+    text = INSTALL_SH.read_text()
+
+    check_node_body = text.split("check_node()", 1)[1].split("\ninstall_node()", 1)[0]
+    assert "configure_managed_node_npm_prefix" in check_node_body
+
+    # No-op guard so it's safe to call when there is no managed Node.
+    assert '[ -x "$HERMES_HOME/node/bin/npm" ] || return 0' in text
 
 
 def test_node_bootstrap_redirects_bundled_npm_global_prefix_to_link_dir() -> None:
     text = NODE_BOOTSTRAP.read_text()
 
+    assert "_nb_configure_npm_prefix()" in text
     assert 'printf \'prefix=%s\\n\' "$(dirname "$_link_dir")" > "$HERMES_HOME/node/etc/npmrc"' in text
-    assert '"$HERMES_HOME/node/etc/npmrc"' in text
+
+    # Runs at the top of ensure_node so existing managed installs are repaired
+    # even when a modern Node is already present (early return path).
+    ensure_node_body = text.split("ensure_node()", 1)[1]
+    assert "_nb_configure_npm_prefix" in ensure_node_body
+    assert '[ -x "$HERMES_HOME/node/bin/npm" ] || return 0' in text