more consistent view model display between switching chats

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

@@ -17,8 +17,11 @@ private actor MockSybilClient: SybilAPIClienting {
     private let searchesResponse: [SearchSummary]
     private let chatDetails: [String: ChatDetail]
     private let searchDetails: [String: SearchDetail]
+    private let createChatResponse: ChatSummary?
 
     private var snapshot = MockClientCallSnapshot()
+    private var getChatDelayNanoseconds: UInt64 = 0
+    private var getSearchDelayNanoseconds: UInt64 = 0
     private var completionStreamNetworkErrorMessage: String?
     private var completionStreamDelayNanoseconds: UInt64 = 0
     private var searchStreamNetworkErrorMessage: String?
@@ -28,12 +31,14 @@ private actor MockSybilClient: SybilAPIClienting {
         chatsResponse: [ChatSummary] = [],
         searchesResponse: [SearchSummary] = [],
         chatDetails: [String: ChatDetail] = [:],
-        searchDetails: [String: SearchDetail] = [:]
+        searchDetails: [String: SearchDetail] = [:],
+        createChatResponse: ChatSummary? = nil
     ) {
         self.chatsResponse = chatsResponse
         self.searchesResponse = searchesResponse
         self.chatDetails = chatDetails
         self.searchDetails = searchDetails
+        self.createChatResponse = createChatResponse
     }
 
     func currentSnapshot() -> MockClientCallSnapshot {
@@ -45,6 +50,14 @@ private actor MockSybilClient: SybilAPIClienting {
         completionStreamDelayNanoseconds = delayNanoseconds
     }
 
+    func setGetChatDelay(_ delayNanoseconds: UInt64) {
+        getChatDelayNanoseconds = delayNanoseconds
+    }
+
+    func setGetSearchDelay(_ delayNanoseconds: UInt64) {
+        getSearchDelayNanoseconds = delayNanoseconds
+    }
+
     func setSearchStreamNetworkError(_ message: String, delayNanoseconds: UInt64 = 0) {
         searchStreamNetworkErrorMessage = message
         searchStreamDelayNanoseconds = delayNanoseconds
@@ -60,11 +73,17 @@ private actor MockSybilClient: SybilAPIClienting {
     }
 
     func createChat(title: String?) async throws -> ChatSummary {
+        if let createChatResponse {
+            return createChatResponse
+        }
         throw UnexpectedClientCall()
     }
 
     func getChat(chatID: String) async throws -> ChatDetail {
         snapshot.getChat += 1
+        if getChatDelayNanoseconds > 0 {
+            try await Task.sleep(nanoseconds: getChatDelayNanoseconds)
+        }
         guard let detail = chatDetails[chatID] else {
             throw UnexpectedClientCall()
         }
@@ -90,6 +109,9 @@ private actor MockSybilClient: SybilAPIClienting {
 
     func getSearch(searchID: String) async throws -> SearchDetail {
         snapshot.getSearch += 1
+        if getSearchDelayNanoseconds > 0 {
+            try await Task.sleep(nanoseconds: getSearchDelayNanoseconds)
+        }
         guard let detail = searchDetails[searchID] else {
             throw UnexpectedClientCall()
         }
@@ -293,6 +315,100 @@ private func makeSearchDetail(id: String, date: Date, answer: String) -> SearchD
     #expect(viewModel.selectedSearch?.answerText == "fresh answer")
 }
 
+@MainActor
+@Test func selectingChatClearsStaleTranscriptUntilNewDetailLoads() async throws {
+    let date = Date(timeIntervalSince1970: 1_700_000_210)
+    let staleDetail = makeChatDetail(id: "chat-old", date: date, body: "stale transcript")
+    let freshDetail = makeChatDetail(id: "chat-new", date: date, body: "fresh transcript")
+    let client = MockSybilClient(chatDetails: ["chat-new": freshDetail])
+    await client.setGetChatDelay(50_000_000)
+    let viewModel = SybilViewModel(settings: testSettings(named: #function)) { _ in client }
+    viewModel.isAuthenticated = true
+    viewModel.isCheckingSession = false
+    viewModel.selectedItem = .chat("chat-old")
+    viewModel.selectedChat = staleDetail
+
+    viewModel.select(.chat("chat-new"))
+
+    #expect(viewModel.displayedMessages.isEmpty)
+    #expect(viewModel.isLoadingSelection)
+
+    try await Task.sleep(nanoseconds: 90_000_000)
+
+    #expect(viewModel.displayedMessages.first?.content == "fresh transcript")
+    #expect(!viewModel.isLoadingSelection)
+}
+
+@MainActor
+@Test func navigationSelectionWaitsForFastTranscriptLoad() async throws {
+    let date = Date(timeIntervalSince1970: 1_700_000_220)
+    let detail = makeChatDetail(id: "chat-fast", date: date, body: "loaded before push")
+    let client = MockSybilClient(chatDetails: ["chat-fast": detail])
+    await client.setGetChatDelay(20_000_000)
+    let viewModel = SybilViewModel(settings: testSettings(named: #function)) { _ in client }
+    viewModel.isAuthenticated = true
+    viewModel.isCheckingSession = false
+
+    await viewModel.selectForNavigation(.chat("chat-fast"), preloadTimeout: .milliseconds(500))
+
+    #expect(viewModel.selectedItem == .chat("chat-fast"))
+    #expect(viewModel.displayedMessages.first?.content == "loaded before push")
+    #expect(!viewModel.isLoadingSelection)
+}
+
+@MainActor
+@Test func navigationSelectionTimesOutAndKeepsLoadingTranscript() async throws {
+    let date = Date(timeIntervalSince1970: 1_700_000_230)
+    let detail = makeChatDetail(id: "chat-slow", date: date, body: "loaded after push")
+    let client = MockSybilClient(chatDetails: ["chat-slow": detail])
+    await client.setGetChatDelay(100_000_000)
+    let viewModel = SybilViewModel(settings: testSettings(named: #function)) { _ in client }
+    viewModel.isAuthenticated = true
+    viewModel.isCheckingSession = false
+
+    await viewModel.selectForNavigation(.chat("chat-slow"), preloadTimeout: .milliseconds(10))
+
+    #expect(viewModel.selectedItem == .chat("chat-slow"))
+    #expect(viewModel.displayedMessages.isEmpty)
+    #expect(viewModel.isLoadingSelection)
+
+    try await Task.sleep(nanoseconds: 150_000_000)
+
+    #expect(viewModel.displayedMessages.first?.content == "loaded after push")
+    #expect(!viewModel.isLoadingSelection)
+}
+
+@MainActor
+@Test func newDraftChatDoesNotShowTypingStateFromPreviousSend() async throws {
+    let date = Date(timeIntervalSince1970: 1_700_000_240)
+    let detail = makeChatDetail(id: "chat-typing", date: date, body: "existing transcript")
+    let client = MockSybilClient(chatDetails: ["chat-typing": detail])
+    await client.setCompletionStreamNetworkError(
+        "Network error -1005 while requesting POST: The network connection was lost.",
+        delayNanoseconds: 50_000_000
+    )
+    let viewModel = SybilViewModel(settings: testSettings(named: #function)) { _ in client }
+    viewModel.isAuthenticated = true
+    viewModel.isCheckingSession = false
+    viewModel.selectedItem = .chat("chat-typing")
+    viewModel.selectedChat = detail
+    viewModel.composer = "continue"
+
+    let sendTask = Task {
+        await viewModel.sendComposer()
+    }
+    try await Task.sleep(nanoseconds: 10_000_000)
+
+    #expect(viewModel.isSendingVisibleChat)
+
+    viewModel.startNewChat()
+
+    #expect(viewModel.displayedMessages.isEmpty)
+    #expect(!viewModel.isSendingVisibleChat)
+
+    await sendTask.value
+}
+
 @MainActor
 @Test func backgroundChatStreamInterruptionIsSuppressedUntilForegroundRefresh() async throws {
     let date = Date(timeIntervalSince1970: 1_700_000_300)