feat(zsh): attach to or create tmux session in interactive shells

shell/zsh.nix

@@ -1,8 +1,13 @@
-{ pkgs, theme, ... }:
-let
-  zsh_autosuggest_highlight_style = if theme == "light" then "fg=180" else "fg=10";
-in
 {
+  pkgs,
+  theme,
+  ...
+}: let
+  zsh_autosuggest_highlight_style =
+    if theme == "light"
+    then "fg=180"
+    else "fg=10";
+in {
   programs.zsh = {
     enable = true;
     enableCompletion = true;
@@ -14,6 +19,15 @@ in
     };
 
     initContent = ''
+      # Auto-start tmux if conditions are met
+      if [[ -z "$TMUX" && -z "$SSH_TTY" && $- == *i* ]]; then
+        # Check if tmux is available and terminal supports it
+        if command -v tmux >/dev/null 2>&1; then
+          # Try to attach to existing session, or create new one
+          exec tmux new-session -A -s default
+        fi
+      fi
+
       function set_win_title(){
           local TITLE=$(git config --get remote.origin.url || echo "$PWD")
           echo -ne "\033]0; $(basename "$TITLE") \007"