diff --git a/home/pi.nix b/home/pi.nix
index 59498b3..8082ae5 100644
--- a/home/pi.nix
+++ b/home/pi.nix
@@ -1,9 +1,14 @@
 {
+  config,
   lib,
   pkgs,
   hostConfig,
   ...
 }:
+let
+  npmDir = "${config.xdg.dataHome}/npm";
+  piBin = "${npmDir}/bin/pi";
+in
 lib.mkIf hostConfig.isLinux {
   # Install pi-coding-agent globally via npm at activation time.
   home.activation.installPiAgent = lib.hm.dag.entryAfter [ "writeBoundary" ] ''
@@ -13,11 +18,11 @@ lib.mkIf hostConfig.isLinux {
         pkgs.coreutils
       ]
     }:$PATH"
+    export NPM_CONFIG_USERCONFIG="${config.xdg.configHome}/npm/npmrc"
+    export XDG_DATA_HOME="${config.xdg.dataHome}"
+    export XDG_CACHE_HOME="${config.xdg.cacheHome}"
 
-    npm_prefix="$(npm prefix -g 2>/dev/null)"
-    pkg_dir="$npm_prefix/lib/node_modules/@mariozechner/pi-coding-agent"
-
-    if [ ! -d "$pkg_dir" ]; then
+    if [ ! -d "${npmDir}/lib/node_modules/@mariozechner/pi-coding-agent" ]; then
       npm install -g @mariozechner/pi-coding-agent 2>/dev/null || true
     fi
   '';
@@ -34,13 +39,13 @@ lib.mkIf hostConfig.isLinux {
         pkgs.git
       ]
     }:$PATH"
+    export NPM_CONFIG_USERCONFIG="${config.xdg.configHome}/npm/npmrc"
+    export XDG_DATA_HOME="${config.xdg.dataHome}"
+    export XDG_CACHE_HOME="${config.xdg.cacheHome}"
 
-    npm_prefix="$(npm prefix -g 2>/dev/null)"
-    pi_bin="$npm_prefix/bin/pi"
-
-    if [ -x "$pi_bin" ]; then
+    if [ -x "${piBin}" ]; then
       for pkg in "@e9n/pi-channels" "pi-schedule-prompt" "pi-subagents"; do
-        "$pi_bin" install "npm:$pkg" 2>/dev/null || true
+        "${piBin}" install "npm:$pkg" 2>/dev/null || true
       done
     fi
   '';
diff --git a/hosts/netty/pi-agent.nix b/hosts/netty/pi-agent.nix
index 3802dfa..2175d94 100644
--- a/hosts/netty/pi-agent.nix
+++ b/hosts/netty/pi-agent.nix
@@ -9,23 +9,21 @@ let
     [ -f "${piAgentEnvFile}" ]
   '';
 
+  piBin = "/home/${username}/.local/share/npm/bin/pi";
+
   # Wrapper that exec's pi inside tmux's foreground process so systemd
   # tracks the actual PID. When pi dies, tmux exits, systemd sees it
   # and triggers Restart=on-failure.
   piAgentStart = pkgs.writeShellScript "start-pi-agent" ''
-    export PATH="${pkgs.nodejs_22}/bin:$PATH"
-    npm_prefix="$(npm prefix -g 2>/dev/null)"
-    pi_bin="$npm_prefix/bin/pi"
-
-    if [ ! -x "$pi_bin" ]; then
-      echo "pi binary not found at $pi_bin" >&2
+    if [ ! -x "${piBin}" ]; then
+      echo "pi binary not found at ${piBin}" >&2
       exit 1
     fi
 
     # tmux runs in the foreground (-D) so systemd tracks this process.
     # The inner shell exec's pi so the tmux pane PID *is* the pi PID.
     exec ${pkgs.tmux}/bin/tmux new-session -D -s pi-agent \
-      "exec $pi_bin --chat-bridge"
+      "exec ${piBin} --chat-bridge"
   '';
 in
 {