fix(ios): optimistic comment deletion with revert on failure

ios/LibNovel/LibNovel/Views/BookDetail/CommentsView.swift

@@ -104,22 +104,44 @@ class CommentsViewModel: ObservableObject {
     func deleteComment(commentId: String, parentId: String? = nil) async {
         guard !deletingIds.contains(commentId) else { return }
         deletingIds.insert(commentId)
-        defer { deletingIds.remove(commentId) }
-        do {
-            try await APIClient.shared.deleteComment(commentId: commentId)
+
+        // Optimistic removal — update the UI immediately before the network call
+        var removedComment: BookComment?
+        var removedAtIndex: Int?
         if let parentId {
             if let idx = comments.firstIndex(where: { $0.id == parentId }) {
                 var parent = comments[idx]
+                removedComment = parent.replies?.first(where: { $0.id == commentId })
+                removedAtIndex = idx
                 parent.replies = (parent.replies ?? []).filter { $0.id != commentId }
                 comments[idx] = parent
             }
         } else {
+            removedAtIndex = comments.firstIndex(where: { $0.id == commentId })
+            removedComment = removedAtIndex.map { comments[$0] }
             comments.removeAll { $0.id == commentId }
         }
+
+        do {
+            try await APIClient.shared.deleteComment(commentId: commentId)
         } catch {
-            // Silently ignore — comment may have already been deleted
+            // Revert the optimistic removal on failure
+            if let removed = removedComment {
+                if let parentId, let idx = removedAtIndex {
+                    var parent = comments[idx]
+                    var replies = parent.replies ?? []
+                    replies.append(removed)
+                    replies.sort { $0.created < $1.created }
+                    parent.replies = replies
+                    comments[idx] = parent
+                } else if let idx = removedAtIndex {
+                    comments.insert(removed, at: min(idx, comments.count))
                 }
             }
+        }
+
+        deletingIds.remove(commentId)
+    }
 
     func vote(commentId: String, vote: String, parentId: String? = nil) async {
         guard !votingIds.contains(commentId) else { return }