add reverseSplitBindings option

CHANGELOG

@@ -1,3 +1,14 @@
+2026-05-16
+- The reversed split-window key bindings previously generated by
+  `programs.tmux.enableSensible` are no longer emitted when
+  `system.stateVersion` is 7 or later, so tmux uses its conventional
+  behavior: `%` splits the current pane horizontally and `"` splits it
+  vertically.
+
+  Existing configurations with `system.stateVersion` 6 or earlier keep
+  the previous reversed bindings. You can explicitly choose either
+  behavior with `programs.tmux.reverseSplitBindings`.
+
 2026-02-10
 - Major changes to `homebrew` module
 

modules/programs/tmux.nix

@@ -57,6 +57,17 @@ in
       description = "Enable sensible configuration options for tmux.";
     };
 
+    programs.tmux.reverseSplitBindings = mkOption {
+      type = types.bool;
+      default = config.system.stateVersion <= 6 && cfg.enableSensible;
+      defaultText = literalExpression "config.system.stateVersion <= 6 && config.programs.tmux.enableSensible";
+      example = true;
+      description = ''
+        Whether to reverse the `%` and `"` split-window key bindings
+        emitted by the tmux module.
+      '';
+    };
+
     programs.tmux.enableMouse = mkOption {
       type = types.bool;
       default = false;
@@ -127,8 +138,6 @@ in
       set -s escape-time 0
 
       bind c new-window -c '#{pane_current_path}'
-      bind % split-window -h -c '#{pane_current_path}'
-      bind '"' split-window -v -c '#{pane_current_path}'
 
       # TODO: make these interactive
       bind C new-session
@@ -138,6 +147,11 @@ in
       # set -g utf8 on
     '';
 
+    programs.tmux.tmuxOptions.splitBindings.text = mkIf cfg.reverseSplitBindings ''
+      bind % split-window -v -c '#{pane_current_path}'
+      bind '"' split-window -h -c '#{pane_current_path}'
+    '';
+
     programs.tmux.tmuxOptions.mouse.text = mkIf cfg.enableMouse ''
       set -g mouse on
       setw -g mouse on

modules/system/version.nix

@@ -51,7 +51,7 @@ in
     system.maxStateVersion = mkOption {
       internal = true;
       type = types.int;
-      default = 6;
+      default = 7;
     };
 
     system.darwinLabel = mkOption {