Make first and single item non-collapsible

Model/Entities/Entities.swift

@@ -86,20 +86,28 @@ struct Language: Identifiable, Comparable {
     }
 }
 
-class OutlineItem: ObservableObject, Identifiable {
+final class OutlineItem: ObservableObject, Identifiable {
     let id: String
     let index: Int
     let text: String
     let level: Int
+    let isCollapsible: Bool
     private(set) var children: [OutlineItem]?
 
     @Published var isExpanded = true
+    
+    func asNonCollapsible() -> OutlineItem {
+        let copy = OutlineItem(id: id, index: index, text: text, level: level, isCollapsible: false)
+        copy.children = children
+        return copy
+    }
 
-    init(id: String, index: Int, text: String, level: Int) {
+    init(id: String, index: Int, text: String, level: Int, isCollapsible: Bool = true) {
         self.id = id
         self.index = index
         self.text = text
         self.level = level
+        self.isCollapsible = isCollapsible
     }
 
     convenience init(index: Int, text: String, level: Int) {

ViewModel/BrowserViewModel.swift

@@ -760,10 +760,9 @@ final class BrowserViewModel: NSObject, ObservableObject,
             }
         }
 
-        // if there is only one h1, flatten one level
+        // if there is only one h1, make the first item non collapsible
         if let rootChildren = root.children, rootChildren.count == 1, let rootFirstChild = rootChildren.first {
-            let children = rootFirstChild.removeAllChildren()
-            self.outlineItemTree = [rootFirstChild] + children
+            self.outlineItemTree = [rootFirstChild.asNonCollapsible()]
         } else {
             self.outlineItemTree = root.children ?? []
         }

Views/Buttons/OutlineButton.swift

@@ -90,7 +90,8 @@ struct OutlineButton: View {
 
         var body: some View {
             if let children = item.children {
-                DisclosureGroup(isExpanded: $item.isExpanded) {
+                let isExpanded = item.isCollapsible ? $item.isExpanded : .constant(true)
+                DisclosureGroup(isExpanded: isExpanded) {
                     ForEach(children) { child in
                         OutlineNode(item: child, action: action)
                     }