home: tmux: migrate to 'terminalFeatures'

There are other terminal capabilities I want to override in tmux, so
let's make this type more extensible.

hosts/homes/ambroisie@bazin/default.nix

@@ -12,8 +12,10 @@
       # I use scripts that use the passthrough sequence often on this host
       enablePassthrough = true;
 
+      terminalFeatures = {
         # HTerm uses `xterm-256color` as its `$TERM`, so use that here
-      trueColorTerminals = [ "xterm-256color" ];
+        xterm-256color = { };
+      };
     };
 
     ssh = {

hosts/homes/ambroisie@mousqueton/default.nix

@@ -15,8 +15,10 @@
       # I use scripts that use the passthrough sequence often on this host
       enablePassthrough = true;
 
+      terminalFeatures = {
         # HTerm uses `xterm-256color` as its `$TERM`, so use that here
-      trueColorTerminals = [ "xterm-256color" ];
+        xterm-256color = { };
+      };
     };
   };
 }

hosts/nixos/porthos/home.nix

@@ -8,11 +8,11 @@
       };
     };
 
-    # Allow using 24bit color when SSH-ing from various clients
-    tmux.trueColorTerminals = [
+    # Allow using extended features when SSH-ing from various clients
+    tmux.terminalFeatures = {
       # My usual terminal, e.g: on laptop
-      "alacritty"
-    ];
+      alacritty = { };
+    };
 
     # Always start a tmux session when opening a shell session
     zsh.launchTmux = true;

modules/home/tmux/default.nix

@@ -5,6 +5,14 @@ let
     config.my.home.x.enable
     (config.my.home.wm.windowManager != null)
   ];
+
+  mkTerminalFlags = opt: flag:
+    let
+      mkFlag = term: ''set -as terminal-features ",${term}:${flag}"'';
+      enabledTerminals = lib.filterAttrs (_: v: v.${opt}) cfg.terminalFeatures;
+      terminals = lib.attrNames enabledTerminals;
+    in
+    lib.concatMapStringsSep "\n" mkFlag terminals;
 in
 {
   options.my.home.tmux = with lib; {
@@ -12,16 +20,20 @@ in
 
     enablePassthrough = mkEnableOption "tmux DCS passthrough sequence";
 
-    trueColorTerminals = mkOption {
-      type = with types; listOf str;
-      default = lib.my.nullableToList config.my.home.terminal.program;
-      defaultText = ''
-        `[ config.my.home.terminal.program ]` if it is non-null, otherwise an
-        empty list.
+    terminalFeatures = mkOption {
+      type = with types; attrsOf (submodule {
+        options = {
+          trueColor = my.mkDisableOption "24-bit (RGB) color support";
+        };
+      });
+
+      default = { ${config.my.home.terminal.program} = { }; };
+      defaultText = litteralExpression ''
+        { ''${config.my.home.terminal.program} = { }; };
       '';
-      example = [ "xterm-256color" ];
+      example = { xterm-256color = { }; };
       description = ''
-        $TERM values which should be considered to always support 24-bit color.
+        $TERM values which should be considered to have additional features.
       '';
     };
   };
@@ -90,12 +102,7 @@ in
       }
 
       # Force 24-bit color for each relevant $TERM
-      ${
-        let
-          mkTcFlag = term: ''set -as terminal-features ",${term}:RGB"'';
-        in
-        lib.concatMapStringsSep "\n" mkTcFlag cfg.trueColorTerminals
-      }
+      ${mkTerminalFlags "trueColor" "RGB"}
     '';
   };
 }