diff --git a/install/lib/packages.sh b/install/lib/packages.sh
index 8e1e325..49570b2 100644
--- a/install/lib/packages.sh
+++ b/install/lib/packages.sh
@@ -23,6 +23,14 @@ APT_PACKAGES=(
 
   # fc-cache / fc-list for the Nerd Font install (lib/fonts.sh)
   fontconfig
+
+  # Runtimes Mason uses to install LSPs / formatters / linters / DAPs.
+  # Without these, every npm-/pip-/luarocks-backed Mason package fails.
+  nodejs          # node runtime (for ts_ls, vscode-langservers-extracted, etc.)
+  npm             # JS package manager Mason shells out to
+  python3-pip     # pip for debugpy/ruff/vint/etc.
+  python3-venv    # so Mason can create per-package venvs (PEP 668 on Ubuntu 24.04)
+  luarocks        # for luacheck
 )
 
 install_apt_packages() {