fix(installer): symlink bundled node/npm into command bin dir for FHS root installs

Root installs on Linux (FHS layout, #15608) put the `hermes` command in
`/usr/local/bin` (on PATH) but symlinked the bundled node/npm/npx into
`~/.local/bin`, which isn't on PATH for a stock root shell. `node`/`npm`
were 'command not found' and `hermes dashboard` failed with 'npm is not
available' because its build-on-demand fallback couldn't find npm.

Fix: `install_node()` now symlinks into `get_command_link_dir()` — the same
helper the `hermes` command link already uses — so node/npm/npx land
wherever the command does (`/usr/local/bin` on FHS root, `~/.local/bin`
otherwise, `$PREFIX/bin` on Termux). Non-root and Termux installs are
unchanged.

Also fixes:
- `scripts/lib/node-bootstrap.sh`: adds `_nb_get_link_dir()` mirroring
  the same root/Termux/user logic for the standalone bootstrap path
  (used by `hermes update`, TUI node bootstrap, etc.)
- `hermes_cli/uninstall.py`: `remove_node_symlinks()` now checks all
  candidate directories (`~/.local/bin`, `/usr/local/bin`, `$PREFIX/bin`)
  so root FHS uninstalls don't leave orphan symlinks

Regression from #15608, which created the FHS path for the command but
left `install_node` pointed at the legacy user-local dir.

hermes_cli/uninstall.py

@@ -9,6 +9,7 @@ Provides options for:
 import os
 import shutil
 import subprocess
+import sys
 from pathlib import Path
 
 from hermes_constants import get_hermes_home
@@ -117,27 +118,42 @@ def remove_wrapper_script():
     return removed
 
 
+def _node_symlink_candidate_dirs() -> "list[Path]":
+    """Directories where the installer may have placed node/npm/npx symlinks."""
+    dirs: list[Path] = [Path.home() / ".local" / "bin"]
+    # Root FHS installs put links in /usr/local/bin.
+    if sys.platform == "linux":
+        dirs.append(Path("/usr/local/bin"))
+    # Termux installs put links in $PREFIX/bin.
+    prefix = os.environ.get("PREFIX", "")
+    if prefix and "com.termux" in prefix:
+        dirs.append(Path(prefix) / "bin")
+    return dirs
+
+
 def remove_node_symlinks(hermes_home: Path) -> list:
-    """Remove the node/npm/npx symlinks the installer drops in ~/.local/bin.
+    """Remove the node/npm/npx symlinks the installer placed on PATH.
 
     The POSIX installer (``scripts/install.sh`` / ``scripts/lib/node-bootstrap.sh``)
-    creates::
+    symlinks node/npm/npx into the same directory as the ``hermes`` command:
 
-        ~/.local/bin/node -> $HERMES_HOME/node/bin/node
-        ~/.local/bin/npm  -> $HERMES_HOME/node/bin/npm
-        ~/.local/bin/npx  -> $HERMES_HOME/node/bin/npx
+    - ``/usr/local/bin/`` on root FHS installs (Linux, uid 0)
+    - ``$PREFIX/bin/`` on Termux
+    - ``~/.local/bin/`` otherwise (the common non-root case)
 
-    and prepends ``~/.local/bin`` to PATH, so these shadow an existing Node
-    manager such as nvm.  Symmetrically remove them on uninstall, but *only*
-    when the link still resolves into this Hermes home's ``node`` directory.
-    A link the user has since repointed at nvm (or anything else outside
-    Hermes) is left untouched so we never break unrelated tooling.
+    We check all candidate directories so that uninstall works regardless of
+    how the install was done (e.g. a root FHS install that placed links in
+    ``/usr/local/bin``, or an older install that used ``~/.local/bin`` before
+    the FHS fix).  Only symlinks that resolve into this Hermes home's ``node``
+    directory are removed — links the user has repointed elsewhere (nvm, fnm,
+    etc.) are left untouched.
     """
     node_dir = (hermes_home / "node").resolve()
     removed = []
 
     for name in ("node", "npm", "npx"):
-        link = Path.home() / ".local" / "bin" / name
+        for bin_dir in _node_symlink_candidate_dirs():
+            link = bin_dir / name
             try:
                 # Only act on symlinks — never delete a real binary the user put here.
                 if not link.is_symlink():

scripts/install.sh

@@ -836,16 +836,20 @@ install_node() {
         return 0
     fi
 
-    # Place into ~/.hermes/node/ and symlink binaries to ~/.local/bin/
+    # Place into ~/.hermes/node/ and symlink binaries into the same bin dir
+    # the hermes command uses (get_command_link_dir): /usr/local/bin for root
+    # FHS installs, $PREFIX/bin on Termux, ~/.local/bin otherwise.
     rm -rf "$HERMES_HOME/node"
     mkdir -p "$HERMES_HOME"
     mv "$extracted_dir" "$HERMES_HOME/node"
     rm -rf "$tmp_dir"
 
-    mkdir -p "$HOME/.local/bin"
-    ln -sf "$HERMES_HOME/node/bin/node" "$HOME/.local/bin/node"
-    ln -sf "$HERMES_HOME/node/bin/npm"  "$HOME/.local/bin/npm"
-    ln -sf "$HERMES_HOME/node/bin/npx"  "$HOME/.local/bin/npx"
+    local node_link_dir
+    node_link_dir="$(get_command_link_dir)"
+    mkdir -p "$node_link_dir"
+    ln -sf "$HERMES_HOME/node/bin/node" "$node_link_dir/node"
+    ln -sf "$HERMES_HOME/node/bin/npm"  "$node_link_dir/npm"
+    ln -sf "$HERMES_HOME/node/bin/npx"  "$node_link_dir/npx"
 
     export PATH="$HERMES_HOME/node/bin:$PATH"
 

scripts/lib/node-bootstrap.sh

@@ -44,6 +44,19 @@ _nb_is_termux() {
     [ -n "${TERMUX_VERSION:-}" ] || [[ "${PREFIX:-}" == *"com.termux/files/usr"* ]]
 }
 
+# Where to symlink node/npm/npx so they land on PATH.
+# Mirrors get_command_link_dir() from install.sh: root FHS → /usr/local/bin,
+# Termux → $PREFIX/bin, otherwise ~/.local/bin.
+_nb_get_link_dir() {
+    if _nb_is_termux && [ -n "${PREFIX:-}" ]; then
+        echo "$PREFIX/bin"
+    elif [ "$(id -u)" = 0 ] && [ "$(uname -s)" = "Linux" ]; then
+        echo "/usr/local/bin"
+    else
+        echo "$HOME/.local/bin"
+    fi
+}
+
 _nb_node_major() {
     local v
     v=$(node --version 2>/dev/null | sed 's/^v//' | cut -d. -f1)
@@ -187,10 +200,12 @@ _nb_install_bundled_node() {
     mv "$extracted" "$HERMES_HOME/node"
     rm -rf "$tmp"
 
-    mkdir -p "$HOME/.local/bin"
-    ln -sf "$HERMES_HOME/node/bin/node" "$HOME/.local/bin/node"
-    ln -sf "$HERMES_HOME/node/bin/npm"  "$HOME/.local/bin/npm"
-    ln -sf "$HERMES_HOME/node/bin/npx"  "$HOME/.local/bin/npx"
+    local _link_dir
+    _link_dir="$(_nb_get_link_dir)"
+    mkdir -p "$_link_dir"
+    ln -sf "$HERMES_HOME/node/bin/node" "$_link_dir/node"
+    ln -sf "$HERMES_HOME/node/bin/npm"  "$_link_dir/npm"
+    ln -sf "$HERMES_HOME/node/bin/npx"  "$_link_dir/npx"
     export PATH="$HERMES_HOME/node/bin:$PATH"
 
     _nb_have_modern_node || return 1

tests/hermes_cli/test_uninstall_node_symlinks.py

@@ -130,3 +130,37 @@ def test_only_some_links_present(fake_home):
     assert (local_bin / "node").exists()
     assert not (local_bin / "npm").is_symlink()
     assert not (local_bin / "npx").is_symlink()
+
+
+def test_removes_fhs_symlinks_in_usr_local_bin(fake_home, tmp_path, monkeypatch):
+    """Root FHS installs place node symlinks in /usr/local/bin.
+
+    We monkeypatch _node_symlink_candidate_dirs to return a temp dir standing
+    in for /usr/local/bin so the test doesn't need real root privileges.
+    """
+    hermes_home = fake_home / ".hermes"
+    node_bin = _make_hermes_node(hermes_home)
+
+    # Fake /usr/local/bin as a temp dir with our symlinks.
+    fhs_bin = tmp_path / "usr_local_bin"
+    fhs_bin.mkdir()
+    for name in ("node", "npm", "npx"):
+        (fhs_bin / name).symlink_to(node_bin / name)
+
+    # Ensure ~/.local/bin has NO symlinks (simulate pure FHS install).
+    local_bin = fake_home / ".local" / "bin"
+    for name in ("node", "npm", "npx"):
+        p = local_bin / name
+        if p.exists() or p.is_symlink():
+            p.unlink()
+
+    # Return only our fake FHS dir as a candidate.
+    monkeypatch.setattr(
+        uninstall, "_node_symlink_candidate_dirs", lambda: [fhs_bin]
+    )
+
+    removed = uninstall.remove_node_symlinks(hermes_home)
+
+    assert sorted(p.name for p in removed) == ["node", "npm", "npx"]
+    for name in ("node", "npm", "npx"):
+        assert not (fhs_bin / name).is_symlink()