Create the t script with nix

lib/shared/home-manager-packages.nix

@@ -2,9 +2,54 @@
 let
   php = pkgs.php82;
   phpPackages = pkgs.php82Packages;
+
+  inherit (pkgs) writeShellScriptBin;
+
+  script-t = writeShellScriptBin "t" ''
+    # Credit to ThePrimeagen.
+
+    set -o nounset
+    set -o pipefail
+
+    if [[ $# -eq 1 ]]; then
+      selected=$1
+    else
+      # Get the session name from fuzzy-finding list of directories and generating a
+      # tmux-safe version.
+      items=$(find ~/Code/* ~/Code ~ ~/Documents /tmp \
+        -maxdepth 1 -mindepth 1 -type d \
+        ! -name "*-old" \
+        ! -name "*.old"
+      )
+
+      selected=$(echo "''${items}" | fzf)
+    fi
+
+    if [[ -z "''${selected}" ]]; then
+      exit 0
+    fi
+
+    session_name=$(basename "''${selected}" | sed 's/\./_/g')
+    session_path="''${selected}"
+
+    # Git worktrees.
+    if [[ -e "''${selected}/main" ]]; then
+      session_path="''${selected}/main"
+    fi
+
+    if tmux has-session -t "''${session_name}" 2> /dev/null; then
+      tmux attach -t "''${session_name}"
+    fi
+
+    tmux new-session -d -s "''${session_name}" -c "''${session_path}"
+
+    tmux switch-client -t "''${session_name}" || tmux attach -t "''${session_name}"
+  '';
 in
 with pkgs;
 [
+  script-t
+
   inputs.build-configs.packages.${pkgs.system}.default
 
   awscli2