ios: preserve chat scroll position on resume

ios/Packages/Sybil/Sources/Sybil/SybilChatTranscriptView.swift

@@ -67,7 +67,6 @@ struct SybilChatTranscriptView: View {
             .scrollDismissesKeyboard(.interactively)
             .onAppear {
                 syncKnownToolCallMessageIDs()
-                scrollToBottom(with: proxy, animated: false)
             }
             .onChange(of: toolCallMessageIDSignature) { _, _ in
                 syncKnownToolCallMessageIDs()

ios/Packages/Sybil/Sources/Sybil/SybilViewModel.swift

@@ -1752,13 +1752,16 @@ final class SybilViewModel {
                 switch target {
                 case let .chat(chatID):
                     SybilLog.debug(SybilLog.app, "Refreshing chat \(chatID)")
+                    let isSelectingDifferentChat = selectedChat?.id != chatID
                     let chat = try await client.getChat(chatID: chatID)
                     guard selectedItem == target, draftKind == nil else {
                         return
                     }
                     selectedChat = chat
                     selectedSearch = nil
-                    requestChatBottomPin()
+                    if isSelectingDifferentChat {
+                        requestChatBottomPin()
+                    }
 
                     if let provider = chat.lastUsedProvider,
                        let model = chat.lastUsedModel,

ios/Packages/Sybil/Tests/SybilTests/SybilTests.swift

@@ -544,12 +544,14 @@ private func makeToolCallMessage(id: String, date: Date, summary: String = "Ran
 @MainActor
 @Test func foregroundChatRefreshReloadsSelectedTranscript() async throws {
     let date = Date(timeIntervalSince1970: 1_700_000_100)
+    let staleDetail = makeChatDetail(id: "chat-2", date: date, body: "stale transcript")
     let detail = makeChatDetail(id: "chat-2", date: date, body: "refreshed transcript")
     let client = MockSybilClient(chatDetails: ["chat-2": detail])
     let viewModel = SybilViewModel(settings: testSettings(named: #function)) { _ in client }
     viewModel.isAuthenticated = true
     viewModel.isCheckingSession = false
     viewModel.selectedItem = .chat("chat-2")
+    viewModel.selectedChat = staleDetail
 
     await viewModel.refreshVisibleContent(refreshCollections: false, refreshSelection: true)
 
@@ -559,7 +561,7 @@ private func makeToolCallMessage(id: String, date: Date, summary: String = "Ran
     #expect(snapshot.listSearches == 0)
     #expect(snapshot.getChat == 1)
     #expect(viewModel.selectedChat?.messages.first?.content == "refreshed transcript")
-    #expect(viewModel.chatBottomPinRequestID == 1)
+    #expect(viewModel.chatBottomPinRequestID == 0)
 }
 
 @MainActor
@@ -675,6 +677,7 @@ private func makeToolCallMessage(id: String, date: Date, summary: String = "Ran
 
     #expect(viewModel.displayedMessages.first?.content == "fresh transcript")
     #expect(!viewModel.isLoadingSelection)
+    #expect(viewModel.chatBottomPinRequestID == 1)
 }
 
 @MainActor