Sync post updates from comments view back to feed view

When post data changes in the comments view (e.g., votes, title, comment count), those changes are now reflected in the feed view when navigating back. This is achieved by updating the NavigationStore's selectedPost property whenever the post changes in CommentsViewModel, and having FeedView observe and apply those updates.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <[email protected]>

Author: weiran

Features/Comments/Sources/Comments/CommentsView.swift

@@ -114,6 +114,12 @@ public struct CommentsView<NavigationStore: NavigationStoreProtocol>: View {
         }
         .task {
             votingViewModel.navigationStore = navigationStore
+            // Set up callback to update navigation store when post changes
+            viewModel.onPostUpdated = { [weak navigationStore] updatedPost in
+                if let updatedPost {
+                    navigationStore?.selectedPost = updatedPost
+                }
+            }
             await viewModel.loadComments()
             if let targetID = pendingCommentID {
                 _ = await viewModel.revealComment(withId: targetID)

Features/Comments/Sources/Comments/CommentsViewModel.swift

@@ -14,12 +14,18 @@ import SwiftUI
 @Observable
 public final class CommentsViewModel: @unchecked Sendable {
     public let postID: Int
-    public var post: Post?
+    public var post: Post? {
+        didSet {
+            onPostUpdated?(post)
+        }
+    }
     public var visibleComments: [Comment] = []
     public var showThumbnails: Bool
 
     // Callback for when comments are loaded (used for HTML parsing in the view layer)
     public var onCommentsLoaded: (([Comment]) -> Void)?
+    // Callback for when post is updated
+    public var onPostUpdated: ((Post?) -> Void)?
 
     private let postUseCase: any PostUseCase
     private let commentUseCase: any CommentUseCase

Features/Feed/Sources/Feed/FeedView.swift

@@ -97,6 +97,13 @@ public struct FeedView<NavigationStore: NavigationStoreProtocol>: View {
             votingViewModel.navigationStore = navigationStore
             await viewModel.loadFeed()
         }
+        .onChange(of: navigationStore.selectedPost) { oldPost, newPost in
+            // When selectedPost changes in navigation store (e.g., from comments view),
+            // update it in the feed
+            if let updatedPost = newPost {
+                viewModel.replacePost(updatedPost)
+            }
+        }
         .alert(
             "Vote Error",
             isPresented: Binding(