feat: add mcp-npx wrapper for Node.js MCP servers

Provides npx with Node.js in PATH for MCP server execution.

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

CLAUDE.md

@@ -46,6 +46,15 @@ bosun.secrets.npmrc = { ... };       # Secret definitions
 
 Profile definitions are in `modules/generic/profiles.nix`, implementations in `modules/nixos/profiles/`.
 
+## Adding packages
+
+Before writing a custom `packages/` derivation, always check if the package already exists in nixpkgs:
+- Stable: https://search.nixos.org/packages?channel=25.11&query=<name>
+- Unstable: https://search.nixos.org/packages?channel=unstable&query=<name>
+- Master (bleeding edge): check open PRs at https://github.com/NixOS/nixpkgs/pulls
+
+If it exists in `unstable` or `master` but not stable, pull it via `overlays/unstable.nix` using `channels.unstable` or `channels.master`. Only write a custom `packages/` derivation as a last resort.
+
 ## Architecture patterns
 
 - **import-tree** auto-discovers and imports `.nix` files in `modules/flake/`. Files prefixed with `_` are excluded from auto-import.

flake.lock

@@ -778,11 +778,11 @@
     },
     "master": {
       "locked": {
-        "lastModified": 1771456066,
+        "lastModified": 1771495899,
-        "narHash": "sha256-CLuGt3yg70gnhSam+0qpcWgPnUdY98wVeH4lByklol4=",
+        "narHash": "sha256-UlAN9PHsBx1Kk65gR/KvLfO74zQcOjNZ+d/0td5T8eM=",
         "owner": "NixOS",
         "repo": "nixpkgs",
-        "rev": "be6cf55e819f4d362aa6be60254bbb2537f9a5cb",
+        "rev": "f4f54061a12ebbdd03d7c53eed54d1e135840624",
         "type": "github"
       },
       "original": {

home/by-host/endurance/config/dev.nix

@@ -24,6 +24,9 @@
     nodePackages.typescript-language-server
     nil # nix lsp
 
+    # Node.js for MCP servers
+    nodejs_22
+
     # trurl # Parsing and manipulating URLs via CLI
     pandoc # Document converter
     ripgrep # Grep file search
@@ -39,6 +42,7 @@
     gitui
     tea
     harbor.agent-deck # Terminal session manager for AI coding agents
+    happy-coder # Claude Code mobile client (happy.engineering)
     harbor.oryx # TUI for sniffing network traffic using eBPF
 
     # BMAD
@@ -83,33 +87,48 @@
       enable = true;
       # package = inputs.unstable.${system}.claude-code;
 
-      # mcpServers = {
+      mcpServers = {
-      #   fetch = {
+        # Official MCP servers (require Node.js)
-      #     args = ["-y" "@modelcontextprotocol/server-fetch"];
+        fetch = {
-      #     command = "npx";
+          command = "npx";
-      #     type = "stdio";
+          args = ["-y" "@modelcontextprotocol/server-fetch"];
-      #   };
+          type = "stdio";
-      #   playwright = {
+        };
-      #     args = ["-y" "@modelcontextprotocol/server-playwright"];
+        playwright = {
-      #     command = "npx";
+          command = "npx";
-      #     type = "stdio";
+          args = ["-y" "@modelcontextprotocol/server-playwright"];
-      #   };
+          type = "stdio";
-      #   stackexchange = {
+        };
-      #     args = ["-y" "mcp-server-stackexchange"];
+        stackexchange = {
-      #     command = "npx";
+          command = "npx";
-      #     type = "stdio";
+          args = ["-y" "mcp-server-stackexchange"];
-      #   };
+          type = "stdio";
-      #   arxiv = {
+        };
-      #     args = ["-y" "mcp-server-arxiv"];
+        arxiv = {
-      #     command = "npx";
+          command = "npx";
-      #     type = "stdio";
+          args = ["-y" "mcp-server-arxiv"];
-      #   };
+          type = "stdio";
-      #   claudezilla = {
+        };
-      #     command = "bun";
+
-      #     args = ["/home/toph/code/vendor/claudezilla/mcp/server.js"];
+        # Custom MCP servers
-      #     type = "stdio";
+        claudezilla = {
-      #   };
+          command = "bun";
-      # };
+          args = ["/home/toph/code/vendor/claudezilla/mcp/server.js"];
+          type = "stdio";
+        };
+
+        # Charlie MCP servers (local)
+        charlie-memory = {
+          command = "bun";
+          args = ["/home/toph/agent/mcp/memory/index.js"];
+          type = "stdio";
+        };
+        charlie-comunica = {
+          command = "bun";
+          args = ["/home/toph/agent/mcp/comunica/index.js"];
+          type = "stdio";
+        };
+      };
     };
   };
 }

home/by-host/endurance/hyprland/settings.nix

@@ -46,7 +46,7 @@
         enabled = true;
         size = 4;
         passes = 2;
-        noise = 0.3;
+        noise = 0.05;
       };
       shadow = {
         enabled = true;
@@ -69,6 +69,16 @@
 
     # Single tiled window on main monitor: give it breathing room
     workspace = [
+      # Pin workspaces to monitors
+      "1, monitor:HDMI-A-1, default:true"
+      "2, monitor:HDMI-A-1"
+      "3, monitor:HDMI-A-1"
+      "4, monitor:HDMI-A-1"
+      "5, monitor:HDMI-A-1"
+      "6, monitor:DP-3, default:true"
+      "7, monitor:DP-3"
+      "8, monitor:DP-3"
+      # Single tiled window on main monitor: give it breathing room
       "w[t1] m[HDMI-A-1], gapsout:15 840 15 840"
     ];
 

home/by-host/endurance/hyprland/window-rules.nix

@@ -1,6 +1,9 @@
 {...}: {
   wayland.windowManager.hyprland.settings = {
     windowrulev2 = [
+      # Prevent garbage frame flash before first render
+      "immediate, class:.*"
+
       # Privacy: block from screen capture
       "noscreenshare, class:^(1password)$"
       "noscreenshare, class:^(thunderbird)$"
@@ -21,8 +24,9 @@
       # Kitty: slight transparency
       "opacity 0.97 0.97, class:^(kitty)$"
 
-      # JetBrains: suppress phantom windows
+      # JetBrains: suppress phantom windows (RE2 doesn't support lookaheads,
-      "nofocus, class:^jetbrains-(?!toolbox), floating:1, title:^win\\d+$"
+      # so we can't exclude toolbox here — apply per-IDE if needed)
+      # "nofocus, class:^(jetbrains-idea|jetbrains-rider|jetbrains-clion)$, floating:1, title:^win\\d+$"
     ];
   };
 }

modules/flake/args.nix

@@ -24,6 +24,7 @@
             inherit lib;
             pkgs = prev;
           };
+          harbor = inputs.self.packages.${system} or {};
         })
       ];
     };

overlays/unstable.nix

@@ -17,5 +17,5 @@
     # open-webui
     ;
 
-  inherit (channels.master) install-nothing marimo;
+  inherit (channels.master) install-nothing marimo happy-coder;
 }

packages/active-path/active-path

@@ -0,0 +1,116 @@
+#!/usr/bin/env bash
+# active-path <pid>
+#
+# Given a PID (e.g. from active-window), output the active working directory
+# or project root for that process. Handles:
+#   - VSCode/Electron: parses --folder-uri from the process tree
+#   - Terminals (kitty, etc.): finds the deepest meaningful cwd in the tree
+#   - Fallback: own cwd
+
+set -o errexit
+set -o nounset
+set -o pipefail
+
+PID="${1:?Usage: active-path <pid>}"
+
+PROJECT_MARKERS=(.git Cargo.toml package.json Gemfile pyproject.toml go.mod flake.nix)
+
+# Walk up from a path looking for a project root marker.
+# Returns the marker directory, or the original path if nothing is found.
+find_project_root() {
+  local dir="$1"
+  local d="$dir"
+  while [[ "$d" != "/" && -n "$d" ]]; do
+    for marker in "${PROJECT_MARKERS[@]}"; do
+      [[ -e "$d/$marker" ]] && { printf '%s\n' "$d"; return 0; }
+    done
+    d="$(dirname "$d")"
+  done
+  printf '%s\n' "$dir"
+}
+
+# Decode a percent-encoded URI path component (file:/// paths are rarely
+# exotic, but spaces and non-ASCII chars do occur).
+url_decode() {
+  printf '%b' "${1//%/\\x}"
+}
+
+# Read null-terminated argv of a pid and look for --folder-uri.
+# Prints the decoded path and returns 0 if found, else returns 1.
+folder_uri_from_cmdline() {
+  local pid="$1"
+  local prev=""
+  while IFS= read -r -d $'\0' arg; do
+    case "$arg" in
+      --folder-uri=file://*)
+        url_decode "${arg#--folder-uri=file://}"
+        return 0
+        ;;
+      file://*)
+        if [[ "$prev" == "--folder-uri" ]]; then
+          url_decode "${arg#file://}"
+          return 0
+        fi
+        ;;
+    esac
+    prev="$arg"
+  done < "/proc/$pid/cmdline" 2>/dev/null
+  return 1
+}
+
+# Collect PIDs of all processes in the subtree rooted at $1.
+all_pids() {
+  local pid="$1"
+  printf '%s\n' "$pid"
+  for child in $(pgrep -P "$pid" 2>/dev/null); do
+    all_pids "$child"
+  done
+}
+
+# Given a list of PIDs, return the most specific (longest) cwd that lives
+# under the user's home directory.  Falls back to any non-root, non-proc cwd.
+best_cwd_from_pids() {
+  local best=""
+  for pid in "$@"; do
+    local cwd
+    cwd=$(readlink -f "/proc/$pid/cwd" 2>/dev/null) || continue
+    [[ "$cwd" == "/" || "$cwd" == "/root" || "$cwd" == "${HOME}" ]] && continue
+    [[ "$cwd" =~ ^/(proc|sys|run|dev) ]] && continue
+
+    # Prefer paths under home; among those prefer longer (more specific) ones
+    if [[ "$cwd" == "${HOME}"/* ]]; then
+      if [[ -z "$best" || "${#cwd}" -gt "${#best}" ]]; then
+        best="$cwd"
+      fi
+    elif [[ -z "$best" ]]; then
+      best="$cwd"
+    fi
+  done
+  [[ -n "$best" ]] && printf '%s\n' "$best"
+}
+
+# --- Main ---
+
+readarray -t TREE < <(all_pids "$PID")
+
+# 1. VSCode / Electron: search entire process tree for --folder-uri
+for pid in "${TREE[@]}"; do
+  if path=$(folder_uri_from_cmdline "$pid" 2>/dev/null); then
+    find_project_root "$path"
+    exit 0
+  fi
+done
+
+# 2. Terminal / generic: find the best cwd among all processes in the tree
+#    (prefers the shell or its running child over the terminal emulator itself,
+#    because terminal emulators typically sit at $HOME while the shell has moved)
+if cwd=$(best_cwd_from_pids "${TREE[@]}"); then
+  find_project_root "$cwd"
+  exit 0
+fi
+
+# 3. Absolute fallback: own cwd, even if it's /
+own=$(readlink -f "/proc/$PID/cwd" 2>/dev/null || true)
+[[ -n "$own" ]] && find_project_root "$own" && exit 0
+
+exit 1

packages/active-path/package.nix

@@ -0,0 +1,6 @@
+{pkgs, ...}:
+pkgs.writeShellApplication {
+  name = "active-path";
+  runtimeInputs = [pkgs.procps];
+  text = builtins.readFile ./active-path;
+}

packages/active-window/package.nix

@@ -0,0 +1,19 @@
+{pkgs, ...}:
+pkgs.writeShellApplication {
+  name = "active-window";
+  runtimeInputs = [pkgs.jq];
+  text = ''
+    if [[ -n "''${NIRI_SOCKET:-}" ]]; then
+      FOCUSED_ID=$(niri msg --json focused-window | jq '.id')
+      niri msg --json windows \
+        | jq --argjson id "$FOCUSED_ID" \
+             '[.[] | select(.id == $id)] | first
+              | {compositor: "niri", class: .app_id, pid: .pid}'
+    elif [[ -n "''${HYPRLAND_INSTANCE_SIGNATURE:-}" ]]; then
+      hyprctl activewindow -j \
+        | jq '{compositor: "hyprland", class: .class, pid: .pid}'
+    else
+      printf '{"compositor":"unknown","class":null,"pid":null}\n'
+    fi
+  '';
+}

packages/mcp-wrapper/default.nix

@@ -0,0 +1,6 @@
+{ pkgs }:
+
+pkgs.writeShellScriptBin "mcp-npx" ''
+  # Wrapper that provides npx with Node.js in PATH
+  exec ${pkgs.nodejs_22}/bin/npx "$@"
+''

packages/quick-zeal/package.nix

@@ -1,5 +1,6 @@
 {pkgs, ...}:
 pkgs.writeShellApplication {
   name = "quick-zeal";
+  runtimeInputs = [pkgs.harbor.active-window pkgs.jq];
   text = builtins.readFile ./quick-zeal;
 }

packages/quick-zeal/quick-zeal

@@ -6,13 +6,14 @@ extract_major_version() {
 }
 
 # Detects the focused window and checks if it's Kitty
-ACTIVE_WINDOW=$(hyprctl activewindow -j | jq -r '.class')
+WINDOW=$(active-window)
+ACTIVE_WINDOW=$(printf '%s' "$WINDOW" | jq -r '.class // empty')
+PID=$(printf '%s' "$WINDOW" | jq -r '.pid // empty')
 
 # Check if the focused window is a Kitty terminal and if it's in a Git repository.
 # If so, determine the project type and open Zeal with the appropriate argument
 zeal_argument=""
 if [[ $ACTIVE_WINDOW == "kitty" ]]; then
-  PID=$(hyprctl activewindow -j | jq -r '.pid')
   CHILD_PID=$(pgrep -P "$PID" | tail -1)
 
   SHELL_CWD=$(readlink -f "/proc/${CHILD_PID}/cwd")

packages/spawn-term/package.nix

@@ -1,25 +1,13 @@
 {pkgs, ...}:
 pkgs.writeNushellApplication {
   name = "spawn-term";
-  runtimeInputs = with pkgs; [kdotool];
+  runtimeInputs = [pkgs.harbor.active-window];
 
   text = ''
-    let compositor = $env.XDG_CURRENT_DESKTOP? | default ""
+    let window = (active-window | from json)
-
+    let window_info = {
-    let window_info = if ($compositor | str contains "niri") {
+      is_kitty: ($window.class? == "kitty"),
-      let focused_window = (niri msg --json focused-window | from json | get id?)
+      pid: $window.pid?
-      if ($focused_window | is-empty) {
-        { is_kitty: false, pid: null }
-      } else {
-        let info = (niri msg --json windows | from json | where id == $focused_window | first)
-        { is_kitty: ($info.app_id? == "kitty"), pid: $info.pid? }
-      }
-    } else {
-      let focused_window = (kdotool getactivewindow)
-      {
-        is_kitty: ((kdotool getwindowclassname $focused_window) == "kitty"),
-        pid: (kdotool getwindowpid $focused_window | into int)
-      }
     }
 
     if $window_info.is_kitty {