refactor: centralize workstation HM base and derive terminal from user metadata

modules/features/niri/default.nix

@@ -41,8 +41,27 @@
           inherit (display) mode;
         }
       ) config.meta.host.displays;
+      rawTerminalAttrPath = lib.splitString "." config.meta.user.terminalPackageAttr;
+      terminalAttrPath =
+        if rawTerminalAttrPath != [ ] && builtins.head rawTerminalAttrPath == "pkgs" then
+          builtins.tail rawTerminalAttrPath
+        else
+          rawTerminalAttrPath;
+      terminalPackage = lib.attrByPath terminalAttrPath null pkgs;
+      hasMainProgram = terminalPackage != null && terminalPackage ? meta.mainProgram;
     in
     {
+      assertions = [
+        {
+          assertion = terminalPackage != null;
+          message = "Unknown terminal package `${config.meta.user.terminalPackageAttr}` for user `${config.meta.user.name}`.";
+        }
+        {
+          assertion = hasMainProgram;
+          message = "Terminal package `${config.meta.user.terminalPackageAttr}` must define `meta.mainProgram`.";
+        }
+      ];
+
       home.sessionVariables.NIXOS_OZONE_WL = "1";
 
       dconf.settings = {
@@ -123,7 +142,16 @@
           mouse.accel-speed = 0.4;
         };
 
-        binds = import ./_bindings.nix;
+        binds =
+          if hasMainProgram then
+            import ./_bindings.nix {
+              inherit
+                lib
+                terminalPackage
+                ;
+            }
+          else
+            { };
       };
     };
 }