nixos: add claude-remote-control always-on service

Always-on systemd user service running `claude --remote-control` in a
detached tmux session (dedicated socket) pinned to /srv/dotfiles, with a
claude-rc-attach alias. Enabled on railbird-sf. Ad-hoc per-directory
sessions remain handled by the tmclaude shell function.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

nixos/claude-remote-control.nix

@@ -0,0 +1,64 @@
+{
+  pkgs,
+  config,
+  lib,
+  makeEnable,
+  ...
+}: let
+  # Working directory the always-on session is pinned to. Ad-hoc sessions in
+  # other directories are handled by the `tmclaude` shell function instead.
+  workingDirectory = "/srv/dotfiles";
+
+  # Dedicated tmux socket + session name so the service owns its own tmux
+  # server (independent of the interactive one). Attach locally with:
+  #   tmux -L claude-rc attach -t claude-rc
+  socket = "claude-rc";
+  sessionName = "claude-rc";
+
+  # Name the session registers under for native Remote Control (phone/web).
+  remoteName = config.networking.hostName;
+
+  # claude shells out to these for its tools; give the service a clean PATH.
+  servicePath = lib.makeBinPath (with pkgs; [
+    claude-code
+    tmux
+    bashInteractive
+    coreutils
+    findutils
+    git
+    gnugrep
+    gnused
+    nix
+    nodejs
+    openssh
+    ripgrep
+    zsh
+  ]);
+in
+  makeEnable config "myModules.claudeRemoteControl" false {
+    home-manager.users.imalison = {
+      systemd.user.services.claude-remote-control = {
+        Unit = {
+          Description = "Claude Code remote-control session";
+          After = ["network.target"];
+        };
+        Service = {
+          # tmux new-session -d daemonizes the server and returns.
+          Type = "forking";
+          Environment = ["PATH=${servicePath}"];
+          ExecStart = lib.concatStringsSep " " [
+            "${pkgs.tmux}/bin/tmux -L ${socket} new-session -d"
+            "-s ${sessionName} -c ${workingDirectory}"
+            "${pkgs.claude-code}/bin/claude --remote-control ${remoteName} --dangerously-skip-permissions"
+          ];
+          ExecStop = "${pkgs.tmux}/bin/tmux -L ${socket} kill-server";
+          Restart = "on-failure";
+          RestartSec = 5;
+        };
+        Install.WantedBy = ["default.target"];
+      };
+
+      # Convenience: attach to the always-on session from any directory.
+      home.shellAliases.claude-rc-attach = "tmux -L ${socket} attach -t ${sessionName}";
+    };
+  }

nixos/configuration.nix

@@ -12,6 +12,7 @@
     ./cache-server.nix
     ./cache.nix
     ./chrome-favicon-dbus.nix
+    ./claude-remote-control.nix
     ./code.nix
     ./cua.nix
     ./desktop.nix

nixos/machines/railbird-sf.nix

@@ -63,6 +63,7 @@
   myModules.base.enable = true;
   myModules.desktop.enable = true;
   myModules.code.enable = true;
+  myModules.claudeRemoteControl.enable = true;
   myModules.syncthing.enable = true;
   myModules.fonts.enable = true;
   myModules.plasma.enable = true;