diff --git a/apps.view.tree b/apps.view.tree
index 5e35710..5d6e279 100644
--- a/apps.view.tree
+++ b/apps.view.tree
@@ -41,7 +41,7 @@ $hyoo_apps $mol_book2
 		release @ \For All
 		develop @ \For Experts
 		preview @ \For Curious
-	apps *
+	apps *$hyoo_apps_app
 		studio *
 			target \develop
 			title @ \Online Studio
diff --git a/apps.view.ts b/apps.view.ts
index 80c28aa..d7cff5d 100644
--- a/apps.view.ts
+++ b/apps.view.ts
@@ -6,7 +6,7 @@ namespace $.$$ {
 			return this.$.$mol_state_arg.value( 'app' )
 		}
 		
-		group_name( id: string ) {
+		group_name( id: keyof ReturnType<typeof this.groups> ) {
 			return this.groups()[ id ]
 		}
 		
diff --git a/type.ts b/type.ts
new file mode 100644
index 0000000..baa979f
--- /dev/null
+++ b/type.ts
@@ -0,0 +1,7 @@
+namespace $ {
+	export type $hyoo_apps_app = {
+		target: string
+		title: string
+		uri: string
+	}
+}