Polish streaming thinking traces

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

@@ -5,6 +5,7 @@ struct SybilChatTranscriptView: View {
     var messages: [Message]
     var isLoading: Bool
     var isSending: Bool
+    var streamingAssistantPresentation: StreamingAssistantPresentation?
     var topContentInset: CGFloat = 0
     var bottomContentInset: CGFloat = 0
     var bottomPinRequestID: Int = 0
@@ -41,7 +42,11 @@ struct SybilChatTranscriptView: View {
                     ForEach(renderItems) { item in
                         switch item {
                         case let .message(message):
-                            MessageBubble(message: message, isSending: isSending)
+                            MessageBubble(
+                                message: message,
+                                isSending: isSending,
+                                streamingAssistantPresentation: streamingAssistantPresentation
+                            )
                                 .frame(maxWidth: .infinity)
                         case let .toolGroup(id, messages):
                             ToolCallStackView(
@@ -140,6 +145,7 @@ func buildTranscriptRenderItems(from messages: [Message]) -> [TranscriptRenderIt
 private struct MessageBubble: View {
     var message: Message
     var isSending: Bool
+    var streamingAssistantPresentation: StreamingAssistantPresentation?
 
     private var toolCallMetadata: ToolCallMetadata? {
         message.toolCallMetadata
@@ -149,10 +155,13 @@ private struct MessageBubble: View {
         message.role == .user
     }
 
-    private var isPendingAssistant: Bool {
-        message.id.hasPrefix("temp-assistant-") &&
-            isSending &&
-            message.content.trimmingCharacters(in: .whitespacesAndNewlines).isEmpty
+    private var isStreamingAssistant: Bool {
+        message.role == .assistant && message.id.hasPrefix("temp-assistant-")
+    }
+
+    private var matchingStreamingAssistantPresentation: StreamingAssistantPresentation? {
+        guard streamingAssistantPresentation?.messageID == message.id else { return nil }
+        return streamingAssistantPresentation
     }
 
     var body: some View {
@@ -174,16 +183,12 @@ private struct MessageBubble: View {
                         )
                     }
 
-                    if isPendingAssistant {
-                        HStack(spacing: 8) {
-                            ProgressView()
-                                .controlSize(.small)
-                                .tint(SybilTheme.primary)
-                            Text("Thinking…")
-                                .font(.sybil(.footnote))
-                                .foregroundStyle(SybilTheme.textMuted)
-                        }
-                        .padding(.vertical, 2)
+                    if isStreamingAssistant {
+                        StreamingAssistantContentView(
+                            content: message.content,
+                            isSending: isSending,
+                            presentation: matchingStreamingAssistantPresentation
+                        )
                     } else if !message.content.trimmingCharacters(in: .whitespacesAndNewlines).isEmpty {
                         Markdown(message.content)
                             .tint(SybilTheme.primary)
@@ -232,6 +237,123 @@ private struct MessageBubble: View {
     }
 }
 
+private struct StreamingTraceHeightPreferenceKey: PreferenceKey {
+    static let defaultValue: CGFloat = 0
+
+    static func reduce(value: inout CGFloat, nextValue: () -> CGFloat) {
+        value = max(value, nextValue())
+    }
+}
+
+struct StreamingAssistantContentView: View {
+    private enum Phase: Hashable {
+        case pending
+        case trace(Int)
+        case answer
+    }
+
+    var content: String
+    var isSending: Bool
+    var presentation: StreamingAssistantPresentation?
+
+    @Environment(\.accessibilityReduceMotion) private var reduceMotion
+    @State private var retainedTraceHeight: CGFloat = 0
+
+    private var traceText: String? {
+        guard let trace = presentation?.ephemeralTrace?.trimmingCharacters(in: .whitespacesAndNewlines),
+              !trace.isEmpty
+        else {
+            return nil
+        }
+        return trace
+    }
+
+    private var hasAnswer: Bool {
+        !content.trimmingCharacters(in: .whitespacesAndNewlines).isEmpty
+    }
+
+    private var phase: Phase {
+        if hasAnswer {
+            return .answer
+        }
+        if traceText != nil {
+            return .trace(presentation?.traceRevision ?? 0)
+        }
+        return .pending
+    }
+
+    private var traceTransition: AnyTransition {
+        guard !reduceMotion else { return .identity }
+        return .asymmetric(
+            insertion: .opacity.combined(with: .offset(y: 5)),
+            removal: .opacity.combined(with: .offset(y: -5))
+        )
+    }
+
+    private var answerTransition: AnyTransition {
+        guard !reduceMotion else { return .identity }
+        return .opacity.combined(with: .offset(y: 3))
+    }
+
+    var body: some View {
+        ZStack(alignment: .topLeading) {
+            if let traceText {
+                Text(traceText)
+                    .font(.sybil(size: 15))
+                    .italic()
+                    .foregroundStyle(SybilTheme.textMuted.opacity(0.88))
+                    .lineSpacing(5)
+                    .fixedSize(horizontal: false, vertical: true)
+                    .opacity(0.78)
+                    .textSelection(.disabled)
+                    .allowsHitTesting(false)
+                    .accessibilityLabel("Assistant is working")
+                    .background {
+                        GeometryReader { geometry in
+                            Color.clear.preference(
+                                key: StreamingTraceHeightPreferenceKey.self,
+                                value: geometry.size.height
+                            )
+                        }
+                    }
+                    .id("thinking-trace-\(presentation?.traceRevision ?? 0)")
+                    .transition(traceTransition)
+                    .zIndex(1)
+            }
+
+            if hasAnswer {
+                Markdown(content)
+                    .tint(SybilTheme.primary)
+                    .foregroundStyle(SybilTheme.text.opacity(0.95))
+                    .markdownTheme(.sybilReadable)
+                    .textSelection(.enabled)
+                    .id("streaming-assistant-answer")
+                    .transition(answerTransition)
+                    .zIndex(2)
+            }
+
+            if isSending && !hasAnswer && traceText == nil {
+                HStack(spacing: 8) {
+                    ProgressView()
+                        .controlSize(.small)
+                        .tint(SybilTheme.primary)
+                    Text("Thinking…")
+                        .font(.sybil(.footnote))
+                        .foregroundStyle(SybilTheme.textMuted)
+                }
+                .padding(.vertical, 2)
+                .transition(reduceMotion ? .identity : .opacity)
+            }
+        }
+        .frame(maxWidth: .infinity, minHeight: max(24, retainedTraceHeight), alignment: .topLeading)
+        .onPreferenceChange(StreamingTraceHeightPreferenceKey.self) { measuredHeight in
+            guard measuredHeight.isFinite, measuredHeight > retainedTraceHeight else { return }
+            retainedTraceHeight = measuredHeight
+        }
+        .animation(reduceMotion ? nil : .easeOut(duration: 0.20), value: phase)
+    }
+}
+
 private struct ToolCallStackView: View {
     private struct CardLayout {
         var x: CGFloat

ios/Packages/Sybil/Sources/Sybil/SybilQuickQuestionView.swift

@@ -62,7 +62,11 @@ struct SybilQuickQuestionView: View {
             VStack(alignment: .leading, spacing: 12) {
                 if hasAnswerContent {
                     ForEach(viewModel.quickQuestionMessages) { message in
-                        QuickQuestionMessageView(message: message, isSending: viewModel.isQuickQuestionSending)
+                        QuickQuestionMessageView(
+                            message: message,
+                            isSending: viewModel.isQuickQuestionSending,
+                            streamingAssistantPresentation: viewModel.quickQuestionStreamingAssistantPresentation
+                        )
                     }
 
                     if let error = viewModel.quickQuestionError {
@@ -263,11 +267,11 @@ private struct QuickQuestionPickerPill: View {
 private struct QuickQuestionMessageView: View {
     var message: Message
     var isSending: Bool
+    var streamingAssistantPresentation: StreamingAssistantPresentation?
 
-    private var isPendingAssistant: Bool {
-        message.id.hasPrefix("temp-assistant-quick-") &&
-            isSending &&
-            message.content.trimmingCharacters(in: .whitespacesAndNewlines).isEmpty
+    private var matchingStreamingAssistantPresentation: StreamingAssistantPresentation? {
+        guard streamingAssistantPresentation?.messageID == message.id else { return nil }
+        return streamingAssistantPresentation
     }
 
     var body: some View {
@@ -276,15 +280,12 @@ private struct QuickQuestionMessageView: View {
                 .font(.caption)
                 .foregroundStyle(SybilTheme.textMuted)
                 .fixedSize(horizontal: false, vertical: true)
-        } else if isPendingAssistant {
-            HStack(spacing: 8) {
-                ProgressView()
-                    .controlSize(.small)
-                    .tint(SybilTheme.primary)
-                Text("Thinking...")
-                    .font(.caption)
-                    .foregroundStyle(SybilTheme.textMuted)
-            }
+        } else if message.id.hasPrefix("temp-assistant-quick-") {
+            StreamingAssistantContentView(
+                content: message.content,
+                isSending: isSending,
+                presentation: matchingStreamingAssistantPresentation
+            )
         } else if !message.content.trimmingCharacters(in: .whitespacesAndNewlines).isEmpty {
             Markdown(message.content)
                 .font(.body)

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

@@ -40,9 +40,72 @@ struct SidebarItem: Identifiable, Hashable {
     var isRunning: Bool
 }
 
+enum StreamingAssistantContentUpdate: Equatable, Sendable {
+    case unchanged
+    case replace(String)
+}
+
+struct StreamingAssistantState: Equatable, Sendable {
+    private(set) var segmentText = ""
+    private(set) var initiatedToolCallIDs: Set<String> = []
+    private(set) var ephemeralTrace: String?
+    private(set) var traceRevision = 0
+
+    mutating func receiveDelta(_ text: String) -> StreamingAssistantContentUpdate {
+        guard !text.isEmpty else { return .unchanged }
+        segmentText += text
+        ephemeralTrace = nil
+        return .replace(segmentText)
+    }
+
+    mutating func receiveToolCall(id: String, status: String) -> StreamingAssistantContentUpdate {
+        guard status.lowercased() == "initiated", initiatedToolCallIDs.insert(id).inserted else {
+            return .unchanged
+        }
+
+        let trace = segmentText.trimmingCharacters(in: .whitespacesAndNewlines)
+        segmentText = ""
+        if !trace.isEmpty {
+            ephemeralTrace = trace
+            traceRevision += 1
+        }
+        return .replace("")
+    }
+
+    mutating func receiveDone(_ text: String) -> StreamingAssistantContentUpdate {
+        segmentText = ""
+        ephemeralTrace = nil
+        return .replace(text)
+    }
+
+    mutating func receiveError() -> StreamingAssistantContentUpdate {
+        segmentText = ""
+        ephemeralTrace = nil
+        return .unchanged
+    }
+}
+
+struct StreamingAssistantPresentation: Equatable, Sendable {
+    var messageID: String
+    var ephemeralTrace: String?
+    var traceRevision: Int
+}
+
 private struct PendingChatState {
     var chatID: String?
     var messages: [Message]
+    var streamingAssistantState = StreamingAssistantState()
+
+    var streamingAssistantPresentation: StreamingAssistantPresentation? {
+        guard let messageID = messages.last(where: { $0.id.hasPrefix("temp-assistant-") })?.id else {
+            return nil
+        }
+        return StreamingAssistantPresentation(
+            messageID: messageID,
+            ephemeralTrace: streamingAssistantState.ephemeralTrace,
+            traceRevision: streamingAssistantState.traceRevision
+        )
+    }
 }
 
 private enum ActiveSendContext: Hashable {
@@ -125,6 +188,7 @@ final class SybilViewModel {
     var quickQuestionSubmittedModel: String?
     var isQuickQuestionSending = false
     var isConvertingQuickQuestion = false
+    private var quickQuestionStreamingAssistantState = StreamingAssistantState()
 
     @ObservationIgnored
     private var hasBootstrapped = false
@@ -360,6 +424,30 @@ final class SybilViewModel {
         return canonical
     }
 
+    var displayedStreamingAssistantPresentation: StreamingAssistantPresentation? {
+        if case let .chat(chatID) = selectedItem,
+           let pending = pendingChatStates[chatID] {
+            return pending.streamingAssistantPresentation
+        }
+
+        if draftKind == .chat, let pending = pendingDraftChatState {
+            return pending.streamingAssistantPresentation
+        }
+
+        return nil
+    }
+
+    var quickQuestionStreamingAssistantPresentation: StreamingAssistantPresentation? {
+        guard let messageID = quickQuestionMessages.last(where: { $0.id.hasPrefix("temp-assistant-quick-") })?.id else {
+            return nil
+        }
+        return StreamingAssistantPresentation(
+            messageID: messageID,
+            ephemeralTrace: quickQuestionStreamingAssistantState.ephemeralTrace,
+            traceRevision: quickQuestionStreamingAssistantState.traceRevision
+        )
+    }
+
     var displayedSearch: SearchDetail? {
         if case let .search(searchID) = selectedItem,
            let activeSearch = activeSearchDetails[searchID] {
@@ -620,6 +708,7 @@ final class SybilViewModel {
         quickQuestionTask = nil
         quickQuestionRunID = nil
         isQuickQuestionSending = false
+        quickQuestionStreamingAssistantState = StreamingAssistantState()
     }
 
     @discardableResult
@@ -1140,6 +1229,7 @@ final class SybilViewModel {
         quickQuestionSubmittedPrompt = prompt
         quickQuestionSubmittedProvider = provider
         quickQuestionSubmittedModel = model
+        quickQuestionStreamingAssistantState = StreamingAssistantState()
         quickQuestionMessages = [
             Message(
                 id: "temp-assistant-quick-\(UUID().uuidString)",
@@ -1184,6 +1274,8 @@ final class SybilViewModel {
                 return
             }
 
+            let update = quickQuestionStreamingAssistantState.receiveError()
+            applyQuickQuestionAssistantContentUpdate(update)
             quickQuestionError = normalizeAPIError(error)
             SybilLog.error(SybilLog.ui, "Quick question failed", error: error)
         }
@@ -1198,17 +1290,16 @@ final class SybilViewModel {
             upsertQuickQuestionToolCallMessage(payload)
 
         case let .delta(payload):
-            guard !payload.text.isEmpty else { return }
-            mutateQuickQuestionAssistantMessage { existing in
-                existing + payload.text
-            }
+            let update = quickQuestionStreamingAssistantState.receiveDelta(payload.text)
+            applyQuickQuestionAssistantContentUpdate(update)
 
         case let .done(payload):
-            mutateQuickQuestionAssistantMessage { _ in
-                payload.text
-            }
+            let update = quickQuestionStreamingAssistantState.receiveDone(payload.text)
+            applyQuickQuestionAssistantContentUpdate(update)
 
         case let .error(payload):
+            let update = quickQuestionStreamingAssistantState.receiveError()
+            applyQuickQuestionAssistantContentUpdate(update)
             await streamStatus.setError(payload.message)
 
         case .ignored:
@@ -1607,21 +1698,28 @@ final class SybilViewModel {
             }
 
             serverActiveChatIDs.remove(chatID)
-            pendingChatStates[chatID] = nil
             await refreshCollections(preferredSelection: selectedItem, refreshSelection: false, attachVisibleActiveRun: false)
 
             if selectedItem == selection, draftKind == nil {
-                selectedChat = try await client.getChat(chatID: chatID)
-                selectedSearch = nil
+                let refreshedChat = try await client.getChat(chatID: chatID)
+                if selectedItem == selection, draftKind == nil {
+                    selectedChat = refreshedChat
+                    selectedSearch = nil
+                }
             }
+            pendingChatStates[chatID] = nil
         } catch {
             serverActiveChatIDs.remove(chatID)
-            pendingChatStates[chatID] = nil
+            defer {
+                pendingChatStates[chatID] = nil
+            }
 
             if isCancellation(error) {
                 return
             }
 
+            applyPendingAssistantError(chatID: chatID)
+
             if isActiveStreamNotFound(error) {
                 SybilLog.info(SybilLog.app, "Active chat stream \(chatID) no longer exists")
             } else if shouldSuppressInactiveTransportError(error) {
@@ -1635,8 +1733,11 @@ final class SybilViewModel {
 
             if selectedItem == selection, draftKind == nil {
                 do {
-                    selectedChat = try await client().getChat(chatID: chatID)
-                    selectedSearch = nil
+                    let refreshedChat = try await client().getChat(chatID: chatID)
+                    if selectedItem == selection, draftKind == nil {
+                        selectedChat = refreshedChat
+                        selectedSearch = nil
+                    }
                 } catch {
                     SybilLog.warning(SybilLog.app, "Chat refresh after attach failure failed: \(SybilLog.describe(error))")
                 }
@@ -1856,6 +1957,13 @@ final class SybilViewModel {
         } else {
             pendingDraftChatState = PendingChatState(chatID: nil, messages: optimisticMessages)
         }
+        defer {
+            if let resolvedChatID = chatID {
+                pendingChatStates[resolvedChatID] = nil
+            } else {
+                clearPendingChatState(for: sendContext)
+            }
+        }
         requestChatBottomPin()
 
         if chatID == nil {
@@ -2045,17 +2153,13 @@ final class SybilViewModel {
             upsertPendingToolCallMessage(payload, chatID: chatID)
 
         case let .delta(payload):
-            guard !payload.text.isEmpty else { return }
-            mutatePendingAssistantMessage(chatID: chatID) { existing in
-                existing + payload.text
-            }
+            applyPendingAssistantDelta(payload.text, chatID: chatID)
 
         case let .done(payload):
-            mutatePendingAssistantMessage(chatID: chatID) { _ in
-                payload.text
-            }
+            finalizePendingAssistant(payload.text, chatID: chatID)
 
         case let .error(payload):
+            applyPendingAssistantError(chatID: chatID)
             await streamStatus.setError(payload.message)
 
         case .ignored:
@@ -2233,29 +2337,68 @@ final class SybilViewModel {
         }
     }
 
-    private func mutatePendingAssistantMessage(chatID: String, _ transform: (String) -> String) {
+    private func applyPendingAssistantDelta(_ text: String, chatID: String) {
         guard var pending = pendingChatStates[chatID], !pending.messages.isEmpty else {
             return
         }
 
-        let index = pending.messages.indices.last { pending.messages[$0].id.hasPrefix("temp-assistant-") }
-        guard let index else {
-            return
-        }
-
-        var message = pending.messages[index]
-        message.content = transform(message.content)
-        pending.messages[index] = message
+        let update = pending.streamingAssistantState.receiveDelta(text)
+        applyStreamingAssistantContentUpdate(
+            update,
+            to: &pending.messages,
+            assistantMessagePrefix: "temp-assistant-"
+        )
         pendingChatStates[chatID] = pending
     }
 
-    private func mutateQuickQuestionAssistantMessage(_ transform: (String) -> String) {
-        let index = quickQuestionMessages.indices.last { quickQuestionMessages[$0].id.hasPrefix("temp-assistant-quick-") }
-        guard let index else {
+    private func finalizePendingAssistant(_ text: String, chatID: String) {
+        guard var pending = pendingChatStates[chatID], !pending.messages.isEmpty else {
             return
         }
 
-        quickQuestionMessages[index].content = transform(quickQuestionMessages[index].content)
+        let update = pending.streamingAssistantState.receiveDone(text)
+        applyStreamingAssistantContentUpdate(
+            update,
+            to: &pending.messages,
+            assistantMessagePrefix: "temp-assistant-"
+        )
+        pendingChatStates[chatID] = pending
+    }
+
+    private func applyPendingAssistantError(chatID: String) {
+        guard var pending = pendingChatStates[chatID] else {
+            return
+        }
+
+        let update = pending.streamingAssistantState.receiveError()
+        applyStreamingAssistantContentUpdate(
+            update,
+            to: &pending.messages,
+            assistantMessagePrefix: "temp-assistant-"
+        )
+        pendingChatStates[chatID] = pending
+    }
+
+    private func applyQuickQuestionAssistantContentUpdate(_ update: StreamingAssistantContentUpdate) {
+        applyStreamingAssistantContentUpdate(
+            update,
+            to: &quickQuestionMessages,
+            assistantMessagePrefix: "temp-assistant-quick-"
+        )
+    }
+
+    private func applyStreamingAssistantContentUpdate(
+        _ update: StreamingAssistantContentUpdate,
+        to messages: inout [Message],
+        assistantMessagePrefix: String
+    ) {
+        guard case let .replace(content) = update,
+              let index = messages.indices.last(where: { messages[$0].id.hasPrefix(assistantMessagePrefix) })
+        else {
+            return
+        }
+
+        messages[index].content = content
     }
 
     private func upsertPendingToolCallMessage(_ payload: CompletionStreamToolCall, chatID: String) {
@@ -2263,6 +2406,16 @@ final class SybilViewModel {
             return
         }
 
+        let update = pending.streamingAssistantState.receiveToolCall(
+            id: payload.toolCallId,
+            status: payload.status
+        )
+        applyStreamingAssistantContentUpdate(
+            update,
+            to: &pending.messages,
+            assistantMessagePrefix: "temp-assistant-"
+        )
+
         if let existingIndex = pending.messages.firstIndex(where: { $0.toolCallMetadata?.toolCallId == payload.toolCallId || $0.id == "temp-tool-\(payload.toolCallId)" }) {
             pending.messages[existingIndex] = toolCallMessage(for: payload, id: pending.messages[existingIndex].id)
             pendingChatStates[chatID] = pending
@@ -2281,6 +2434,12 @@ final class SybilViewModel {
     }
 
     private func upsertQuickQuestionToolCallMessage(_ payload: CompletionStreamToolCall) {
+        let update = quickQuestionStreamingAssistantState.receiveToolCall(
+            id: payload.toolCallId,
+            status: payload.status
+        )
+        applyQuickQuestionAssistantContentUpdate(update)
+
         if let existingIndex = quickQuestionMessages.firstIndex(where: { $0.toolCallMetadata?.toolCallId == payload.toolCallId || $0.id == "temp-tool-\(payload.toolCallId)" }) {
             quickQuestionMessages[existingIndex] = toolCallMessage(for: payload, id: quickQuestionMessages[existingIndex].id)
             return
@@ -2430,7 +2589,8 @@ final class SybilViewModel {
 
     private func clearPendingChatState(for context: ActiveSendContext) {
         switch context {
-        case .draftChat:
+        case let .draftChat(identity):
+            guard draftKind == .chat, draftIdentity == identity else { return }
             pendingDraftChatState = nil
         case let .chat(chatID):
             pendingChatStates[chatID] = nil

ios/Packages/Sybil/Sources/Sybil/SybilWorkspaceView.swift

@@ -193,6 +193,7 @@ struct SybilWorkspaceView: View {
                         messages: viewModel.displayedMessages,
                         isLoading: viewModel.isLoadingSelection,
                         isSending: viewModel.isSendingVisibleChat,
+                        streamingAssistantPresentation: viewModel.displayedStreamingAssistantPresentation,
                         topContentInset: showsCustomWorkspaceNavigation ? customWorkspaceNavigationContentInset : 0,
                         bottomContentInset: viewModel.showsComposer ? composerOverlayContentInset : 0,
                         bottomPinRequestID: viewModel.chatBottomPinRequestID