feat: add metrics exporters for Dovecot and Postfix, update Signal execution command, and improve configuration management

shell.nix

@@ -0,0 +1,57 @@
+with import <nixpkgs> { };
+
+let
+  # 1. Import mcp-servers-nix (classic default.nix) from GitHub.
+  #    This provides `mcpServers.lib.mkConfig` and the individual server packages.
+  mcpServers = import (builtins.fetchTarball {
+    url = "https://github.com/natsukium/mcp-servers-nix/archive/refs/heads/main.tar.gz";
+    # Optionally pin with sha256 once known.
+  }) { inherit pkgs; };
+
+  # 3. Build the JSON configuration string with exactly fetch, memory, and brave-search.
+  #    We assume you store your Brave Search API key in "~/.config/mcp-servers/brave.env"
+  mcpConfig = mcpServers.lib.mkConfig pkgs {
+    programs = {
+      # fetch.enable = true;
+      filesystem = {
+        enable = true;
+        args = [ "/home/${builtins.getEnv "USER"}/projects/cloonar/cloonar-nixos/" ];
+      };
+      git = {
+        enable = true;
+        args = [ "/home/${builtins.getEnv "USER"}/projects/cloonar/cloonar-nixos/" ];
+      };
+      sequential-thinking.enable = true;
+      # memory.enable        = true;
+      "brave-search" = {
+        enable  = true;
+        envFile = "/home/${builtins.getEnv "USER"}/.config/mcp-servers/brave.env";
+      };
+    };
+    settings = {
+      mcpServers = {
+        nixos = {
+          command = "nix";
+          args = ["run" "github:utensils/mcp-nixos" "--"];
+        };
+      };
+    };
+  };
+
+in
+
+pkgs.mkShell {
+  # 4. Bring in 'jq' so you can inspect the JSON if needed.
+  buildInputs = [ pkgs.jq ];
+
+  # 5. On shell entry, write out 'claude_desktop_config.json' in the project root.
+  shellHook = ''
+    if [ -f ./.roo/mcp.json ]; then
+      echo "Removing old mcp.json…"
+      rm ./.roo/mcp.json
+    fi
+    echo "Generating mcp.json…"
+    ln -s ${builtins.toString mcpConfig} ./.roo/mcp.json
+    echo "✅ mcp.json has been created."
+  '';
+}