adds quick question UI for mac catalyst target

docs/api/rest.md

@@ -89,6 +89,8 @@ Behavior notes:
       "type": "chat",
       "id": "chat-id",
       "title": "optional title",
+      "parentChatId": null,
+      "titleGenerationPending": false,
       "createdAt": "2026-02-14T00:00:00.000Z",
       "updatedAt": "2026-02-14T00:00:00.000Z",
       "starred": true,
@@ -117,7 +119,8 @@ Behavior notes:
 Behavior notes:
 - This endpoint is intended for combined conversation/search lists such as sidebars.
 - The legacy `GET /v1/chats` and `GET /v1/searches` endpoints remain available for clients that need separate collections.
-- The response currently combines up to 100 chats and up to 100 searches.
+- The response currently combines the 100 most recently updated chats, any additional root chats needed to group those forks, and up to 100 searches.
+- Root chats have `parentChatId: null`. Every fork points directly to its single root chat, including a fork created from another fork, so clients can group rows without traversing a fork chain.
 - `starred`/`starredAt` are backed by membership in a reserved `Project` with id `starred`; future project folders can reuse the same project item model.
 
 ## Chats
@@ -148,15 +151,32 @@ Behavior notes:
 
 Behavior notes:
 - `provider` and `model` must be supplied together when present.
+- Newly created non-fork chats have `parentChatId: null` and `titleGenerationPending: false`.
 - When `provider`/`model` are supplied, the new chat initializes `initiatedProvider`/`initiatedModel` and `lastUsedProvider`/`lastUsedModel`.
 - `additionalSystemPrompt` is trimmed and stored on the chat; blank values are stored as `null`.
 - `enabledTools` stores the enabled Sybil-managed tool names for future chat completions. Unknown tool names are ignored; omitted values default to all currently available tools.
 - Optional `messages` are inserted as the initial transcript. Attachment metadata uses the same schema and limits as chat completion messages.
 
+### `POST /v1/chats/:chatId/fork`
+- Body: `{ "messageId"?: string }`
+- Response: `{ "chat": ChatSummary }`
+- Source chat not found: `404 { "message": "chat not found" }`
+- Supplied message missing from the source chat: `404 { "message": "message not found in chat" }`
+- Supplied message is not an assistant response: `400 { "message": "fork message must be an assistant response" }`
+
+Behavior notes:
+- With no `messageId`, the server copies the complete source transcript. With an assistant response `messageId`, it copies the transcript through that response, inclusive.
+- The source chat is unchanged. Copied messages receive new ids while retaining their role, content, name, creation time, order, and metadata except for the source request's transport-only `clientRequestId`. Attachments and tool-call metadata are retained. LLM call logs, star/project memberships, and other child threads are not copied.
+- The fork inherits the source chat's user, initiated/last-used provider and model, additional system prompt, and enabled tool settings.
+- A fork of a root or another fork always sets `parentChatId` to the single root chat id. Root chats keep `parentChatId: null`.
+- A whole-chat fork starts with `Fork of <source title>` (or `Fork of Untitled chat`). A message fork starts with `Fork of '<message snippet>'`.
+- The placeholder title is returned with `titleGenerationPending: true`. After the first new prompt, call `POST /v1/chats/title/suggest`; the placeholder is eligible for replacement exactly once.
+
 ### `PATCH /v1/chats/:chatId`
 - Body: any subset of `{ "title": string, "additionalSystemPrompt": string|null, "enabledTools": string[] }`
 - Response: `{ "chat": ChatSummary }`
 - Blank titles are rejected. The server trims surrounding whitespace before storing the title.
+- Setting a title clears `titleGenerationPending`, preventing an in-flight or later automatic suggestion from replacing the manual title.
 - `additionalSystemPrompt: null` clears the stored prompt. Blank string values are also stored as `null`.
 - `enabledTools: []` disables Sybil-managed tools for this chat. Omitted settings are left unchanged.
 - Updating chat fields changes the returned chat's `updatedAt`.
@@ -183,14 +203,19 @@ Behavior notes:
 - Response: `{ "chat": ChatSummary }`
 
 Behavior notes:
-- If the chat already has a non-empty title, server returns the existing chat unchanged.
+- If the chat already has a non-empty title and `titleGenerationPending` is false, server returns the existing chat unchanged.
+- A fork placeholder with `titleGenerationPending: true` is eligible for the same title-generation flow as an untitled original chat. A successful or fallback suggestion clears the flag.
 - If a title is set while suggestion generation is in flight, server returns the current chat instead of overwriting that title.
-- When no title exists at write time, server uses OpenAI `gpt-4.1-mini` to generate a one-line title (up to ~4 words), updates the chat title, and returns the updated chat.
+- For an eligible untitled chat or pending fork placeholder, server uses OpenAI `gpt-4.1-mini` to generate a one-line title (up to ~4 words), updates the chat title, and returns the updated chat.
 - If the title provider is unavailable or rejects the request, server still persists a deterministic title derived from the first line of `content` instead of leaving the chat untitled.
 
 ### `DELETE /v1/chats/:chatId`
 - Response: `{ "deleted": true }`
 - Not found: `404 { "message": "chat not found" }`
+- Active chat or fork: `409 { "message": "chat or fork has an active stream" }`
+- Concurrent family deletion: `409 { "message": "chat family deletion already in progress" }`
+- Deleting a root chat also deletes its grouped forks. Deleting a fork leaves the root and sibling forks unchanged.
+- A root cannot be deleted while it or any grouped fork has an active completion stream. A fork cannot be deleted while its own completion stream is active.
 
 ### `GET /v1/chats/:chatId`
 - Response: `{ "chat": ChatDetail }`
@@ -429,6 +454,8 @@ Behavior notes:
 {
   "id": "...",
   "title": null,
+  "parentChatId": null,
+  "titleGenerationPending": false,
   "createdAt": "...",
   "updatedAt": "...",
   "starred": false,
@@ -481,6 +508,8 @@ Behavior notes:
 {
   "id": "...",
   "title": null,
+  "parentChatId": null,
+  "titleGenerationPending": false,
   "createdAt": "...",
   "updatedAt": "...",
   "starred": false,

docs/api/streaming-chat.md

@@ -73,8 +73,10 @@ Notes:
 
 Persisted chat streams with a `chatId` are backend-owned active runs:
 - Once started, the backend keeps the stream running even if the HTTP client disconnects or refreshes.
+- The backend reserves the active run before persisting submitted messages, preventing a root or fork deletion from interleaving with stream setup.
 - While running, `GET /v1/active-runs` includes the `chatId`.
 - Starting a second persisted stream for the same active `chatId` returns `409`, unless its `clientRequestId` matches the active submission, in which case the existing stream is replayed.
+- Starting a persisted stream while that chat family is being deleted returns `409 { "message": "chat family deletion already in progress" }`.
 - Clients can reattach with `POST /v1/chats/:chatId/stream/attach`.
 
 ## Attach Endpoint

ios/Apps/Sybil/Info.plist

@@ -2,6 +2,9 @@
 <!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
 <plist version="1.0">
 <dict>
+	<!-- macOS-only: keep the global Quick Question shortcut available with no windows. -->
+	<key>NSSupportsAutomaticTermination</key>
+	<false/>
 	<key>UIApplicationShortcutItems</key>
 	<array>
 		<dict>

ios/Apps/Sybil/Sources/SybilApp.swift

@@ -8,7 +8,7 @@ struct SybilApp: App
     @UIApplicationDelegateAdaptor(SybilAppDelegate.self) private var appDelegate
 
     var body: some Scene {
-        WindowGroup {
+        WindowGroup(id: SybilCommands.workspaceWindowID) {
             SplitView()
         }
         .commands {
@@ -24,9 +24,18 @@ final class SybilAppDelegate: NSObject, UIApplicationDelegate {
         didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]? = nil
     ) -> Bool {
         SybilHomeScreenQuickActionHandler.configureQuickActions()
+        #if targetEnvironment(macCatalyst)
+        SybilMacQuickQuestionController.shared.start()
+        #endif
         return true
     }
 
+    #if targetEnvironment(macCatalyst)
+    func applicationWillTerminate(_ application: UIApplication) {
+        SybilMacQuickQuestionController.shared.stop()
+    }
+    #endif
+
     func application(
         _ application: UIApplication,
         configurationForConnecting connectingSceneSession: UISceneSession,
@@ -56,11 +65,22 @@ final class SybilSceneDelegate: NSObject, UIWindowSceneDelegate {
         willConnectTo session: UISceneSession,
         options connectionOptions: UIScene.ConnectionOptions
     ) {
+        #if targetEnvironment(macCatalyst)
+        if scene is UIWindowScene, session.role == .windowApplication {
+            SybilMacWindowCommands.shared.windowConnected(sessionID: session.persistentIdentifier)
+        }
+        #endif
         if let shortcutItem = connectionOptions.shortcutItem {
             _ = SybilHomeScreenQuickActionHandler.handle(shortcutItem)
         }
     }
 
+    #if targetEnvironment(macCatalyst)
+    func sceneDidDisconnect(_ scene: UIScene) {
+        SybilMacWindowCommands.shared.windowDisconnected(sessionID: scene.session.persistentIdentifier)
+    }
+    #endif
+
     func windowScene(
         _ windowScene: UIWindowScene,
         performActionFor shortcutItem: UIApplicationShortcutItem,

ios/Apps/Sybil/project.yml

@@ -11,6 +11,13 @@ targets:
     dependencies:
       - package: Sybil
         product: Sybil
+      - target: SybilMacQuickQuestion
+        destinationFilters: [macCatalyst]
+        embed: true
+        link: false
+        codeSign: true
+        copy:
+          destination: plugins
     settings:
       base:
         PRODUCT_BUNDLE_IDENTIFIER: net.buzzert.sybil2
@@ -29,6 +36,7 @@ targets:
         INFOPLIST_KEY_CFBundleDisplayName: Sybil
         INFOPLIST_KEY_ITSAppUsesNonExemptEncryption: NO
         INFOPLIST_KEY_UIApplicationSupportsIndirectInputEvents: YES
+        "INFOPLIST_KEY_UIApplicationSceneManifest_Generation[sdk=macosx*]": YES
         INFOPLIST_KEY_UILaunchScreen_Generation: YES
         INFOPLIST_KEY_UISupportedInterfaceOrientations_iPhone: UIInterfaceOrientationPortrait
         INFOPLIST_KEY_UISupportedInterfaceOrientations_iPad: UIInterfaceOrientationPortrait UIInterfaceOrientationPortraitUpsideDown UIInterfaceOrientationLandscapeLeft UIInterfaceOrientationLandscapeRight

ios/Apps/SybilMacQuickQuestion/Sources/MacQuickQuestionPlugin.swift

@@ -0,0 +1,229 @@
+import AppKit
+import Carbon
+
+// AppKit is unavailable to Catalyst targets. This native bundle uses only
+// public AppKit/Carbon APIs and communicates with the client through Foundation.
+@MainActor
+@objc(SybilMacQuickQuestionPlugin)
+final class MacQuickQuestionPlugin: NSObject, SybilQuickQuestionPanelBridging, NSWindowDelegate {
+    private weak var delegate: (any SybilQuickQuestionPanelDelegate)?
+    private var panel: QuickQuestionPanel?
+    private var panelView: QuickQuestionPanelView?
+    private var hotKey: EventHotKeyRef?
+    private var eventHandler: EventHandlerRef?
+    private var outsideClickMonitor: Any?
+    private var hotKeyState = SybilQuickQuestionHotKeyState()
+    private var isDismissing = false
+    private var shortcutAvailable = false
+    private var windowlessActivity: NSObjectProtocol?
+    private var latestState = SybilQuickQuestionPanelState()
+    private var previousApplication: NSRunningApplication?
+
+    required override init() {
+        super.init()
+    }
+
+    var isVisible: Bool { panel?.isVisible == true }
+
+    func start(delegate: any SybilQuickQuestionPanelDelegate) -> Int32 {
+        self.delegate = delegate
+        if windowlessActivity == nil {
+            // Keep the hotkey service alive with no windows. This option does
+            // not prevent sleep/App Nap or intercept an explicit Quit command.
+            windowlessActivity = ProcessInfo.processInfo.beginActivity(
+                options: .automaticTerminationDisabled,
+                reason: "Quick Question global shortcut"
+            )
+        }
+        guard eventHandler == nil else { return noErr }
+        var eventTypes = [
+            EventTypeSpec(eventClass: OSType(kEventClassKeyboard), eventKind: UInt32(kEventHotKeyPressed)),
+            EventTypeSpec(eventClass: OSType(kEventClassKeyboard), eventKind: UInt32(kEventHotKeyReleased))
+        ]
+        let context = Unmanaged.passUnretained(self).toOpaque()
+        let handlerStatus = InstallEventHandler(
+            GetApplicationEventTarget(),
+            { _, event, context in
+                guard let event, let context else { return OSStatus(eventNotHandledErr) }
+                var identifier = EventHotKeyID()
+                let status = GetEventParameter(
+                    event, EventParamName(kEventParamDirectObject), EventParamType(typeEventHotKeyID),
+                    nil, MemoryLayout<EventHotKeyID>.size, nil, &identifier
+                )
+                guard status == noErr, identifier.signature == 0x53595151, identifier.id == 1 else {
+                    return OSStatus(eventNotHandledErr)
+                }
+                let isKeyDown = GetEventKind(event) == UInt32(kEventHotKeyPressed)
+                let plugin = Unmanaged<MacQuickQuestionPlugin>.fromOpaque(context).takeUnretainedValue()
+                // Application event handlers run on the main event loop.
+                MainActor.assumeIsolated {
+                    if plugin.hotKeyState.shouldToggle(isKeyDown: isKeyDown) {
+                        plugin.delegate?.quickQuestionToggleRequested()
+                    }
+                }
+                return noErr
+            },
+            eventTypes.count, &eventTypes, context, &eventHandler
+        )
+        guard handlerStatus == noErr else { return handlerStatus }
+        let status = RegisterEventHotKey(
+            UInt32(kVK_Space), UInt32(optionKey),
+            EventHotKeyID(signature: 0x53595151, id: 1),
+            GetApplicationEventTarget(), 0, &hotKey
+        )
+        shortcutAvailable = status == noErr
+        return status
+    }
+
+    func updateState(_ data: Data) {
+        guard let state = try? JSONDecoder().decode(SybilQuickQuestionPanelState.self, from: data) else { return }
+        // Updating a background request must not create a non-hosting window.
+        // The controller creates/orders the panel only after UIKit is foreground.
+        latestState = state
+        panelView?.update(state, shortcutAvailable: shortcutAvailable)
+        if isVisible { resizePanel() }
+    }
+
+    func show() {
+        createPanelIfNeeded()
+        guard let panel, let panelView else { return }
+        panelView.update(latestState, shortcutAvailable: shortcutAvailable)
+        let screen = NSScreen.screens.first { $0.frame.contains(NSEvent.mouseLocation) } ?? NSScreen.main
+        let visibleFrame = screen?.visibleFrame ?? NSRect(x: 0, y: 0, width: 1280, height: 800)
+        let width = min(680, visibleFrame.width - 48)
+        panel.setContentSize(NSSize(width: width, height: 240))
+        panelView.layoutSubtreeIfNeeded()
+        let height = min(panelView.preferredHeight, visibleFrame.height - 64)
+        let top = visibleFrame.maxY - min(visibleFrame.height * 0.18, 160)
+        let y = max(visibleFrame.minY + 24, top - height)
+        panel.setFrame(NSRect(x: visibleFrame.midX - width / 2, y: y, width: width, height: height), display: true)
+        // The controller has verified UIKit foreground readiness. A
+        // nonactivating panel can then take focus without raising a workspace.
+        panel.makeKeyAndOrderFront(nil)
+        panel.makeFirstResponder(panelView.promptView)
+        panelView.preparePromptForPresentation()
+        installOutsideClickMonitor()
+    }
+
+    func hide() {
+        dismissPanel(restoringPreviousApplication: true)
+    }
+
+    func activateForQuickQuestion() {
+        if let frontmost = NSWorkspace.shared.frontmostApplication,
+           frontmost != NSRunningApplication.current {
+            previousApplication = frontmost
+        }
+        // Do not order a window here. Catalyst must finish its own foreground
+        // transition before the controller calls show().
+        NSApp.activate()
+    }
+
+    func activateMainWindow() {
+        // An explicit Open in Chat/Open Sybil action keeps focus in Sybil.
+        previousApplication = nil
+        NSApp.activate()
+        NSApp.windows.first { $0 !== panel && $0.canBecomeMain }?.makeKeyAndOrderFront(nil)
+    }
+
+    private func dismissPanel(restoringPreviousApplication: Bool) {
+        guard !isDismissing else { return }
+        let wasVisible = isVisible
+        isDismissing = true
+        if wasVisible { panel?.orderOut(nil) }
+        removeOutsideClickMonitor()
+        isDismissing = false
+        let applicationToRestore = previousApplication
+        previousApplication = nil
+        if restoringPreviousApplication, NSApp.isActive,
+           let applicationToRestore, !applicationToRestore.isTerminated {
+            NSApp.yieldActivation(to: applicationToRestore)
+            applicationToRestore.activate(options: [])
+        }
+        if wasVisible { delegate?.quickQuestionPanelDismissed() }
+    }
+
+    func stop() {
+        previousApplication = nil
+        hide()
+        removeOutsideClickMonitor()
+        if let hotKey { UnregisterEventHotKey(hotKey) }
+        if let eventHandler { RemoveEventHandler(eventHandler) }
+        hotKey = nil
+        eventHandler = nil
+        hotKeyState = SybilQuickQuestionHotKeyState()
+        if let windowlessActivity {
+            ProcessInfo.processInfo.endActivity(windowlessActivity)
+        }
+        windowlessActivity = nil
+        delegate = nil
+    }
+
+    func windowDidResignKey(_ notification: Notification) {
+        // Focus is already moving to a window/app the user chose.
+        dismissPanel(restoringPreviousApplication: false)
+    }
+
+    private func createPanelIfNeeded() {
+        guard panel == nil else { return }
+        let panel = QuickQuestionPanel(
+            contentRect: NSRect(x: 0, y: 0, width: 680, height: 240),
+            styleMask: [.borderless, .nonactivatingPanel], backing: .buffered, defer: false
+        )
+        panel.title = "Quick Question"
+        panel.level = .floating
+        panel.collectionBehavior = [.canJoinAllSpaces, .fullScreenAuxiliary, .transient, .ignoresCycle]
+        panel.isFloatingPanel = true
+        panel.hidesOnDeactivate = false
+        panel.becomesKeyOnlyIfNeeded = false
+        panel.worksWhenModal = true
+        panel.isReleasedWhenClosed = false
+        panel.isOpaque = false
+        panel.backgroundColor = .clear
+        panel.hasShadow = true
+        panel.isMovableByWindowBackground = true
+        panel.appearance = NSAppearance(named: .darkAqua)
+        panel.delegate = self
+        panel.onDismiss = { [weak self] in self?.hide() }
+        let view = QuickQuestionPanelView()
+        view.delegate = delegate
+        view.onDismiss = { [weak self] in self?.hide() }
+        panel.contentView = view
+        panelView = view
+        self.panel = panel
+    }
+
+    private func resizePanel() {
+        guard let panel, let panelView else { return }
+        panelView.layoutSubtreeIfNeeded()
+        let visibleFrame = panel.screen?.visibleFrame ?? panel.frame
+        let height = min(panelView.preferredHeight, visibleFrame.height - 64)
+        guard abs(height - panel.frame.height) > 1 else { return }
+        var frame = panel.frame
+        frame.origin.y = max(visibleFrame.minY + 24, frame.maxY - height)
+        frame.size.height = height
+        panel.setFrame(frame, display: true)
+    }
+
+    private func installOutsideClickMonitor() {
+        guard outsideClickMonitor == nil else { return }
+        // Mouse-only monitoring does not require Accessibility or Input
+        // Monitoring permission. No global keyboard event tap is installed.
+        outsideClickMonitor = NSEvent.addGlobalMonitorForEvents(matching: [.leftMouseDown, .rightMouseDown]) { [weak self] _ in
+            Task { @MainActor [weak self] in self?.hide() }
+        }
+    }
+
+    private func removeOutsideClickMonitor() {
+        if let outsideClickMonitor { NSEvent.removeMonitor(outsideClickMonitor) }
+        outsideClickMonitor = nil
+    }
+}
+
+@MainActor
+private final class QuickQuestionPanel: NSPanel {
+    var onDismiss: (() -> Void)?
+    override var canBecomeKey: Bool { true }
+    override var canBecomeMain: Bool { false }
+    override func cancelOperation(_ sender: Any?) { onDismiss?() }
+}

ios/Apps/SybilMacQuickQuestion/Sources/QuickQuestionPanelView.swift

@@ -0,0 +1,300 @@
+import AppKit
+
+@MainActor
+final class QuickQuestionPanelView: NSVisualEffectView, NSTextViewDelegate {
+    weak var delegate: (any SybilQuickQuestionPanelDelegate)?
+    var onDismiss: (() -> Void)?
+
+    let promptView = QuickQuestionPromptView()
+    private let stack = NSStackView()
+    private let answerView = NSTextView()
+    private let answerScroll = NSScrollView()
+    private let statusLabel = NSTextField(wrappingLabelWithString: "")
+    private let providerPopup = NSPopUpButton()
+    private let modelPopup = NSPopUpButton()
+    private let convertButton = NSButton(title: "Open in Chat", target: nil, action: nil)
+    private let openAppButton = NSButton(title: "Open Sybil", target: nil, action: nil)
+    private let sendButton = NSButton()
+    private let shortcutLabel = NSTextField(labelWithString: "⌥ Space")
+    private var panelState = SybilQuickQuestionPanelState()
+
+    var preferredHeight: CGFloat { stack.fittingSize.height + 40 }
+
+    override init(frame frameRect: NSRect) {
+        super.init(frame: frameRect)
+        material = .hudWindow
+        blendingMode = .behindWindow
+        state = .active
+        wantsLayer = true
+        layer?.cornerRadius = 18
+        layer?.masksToBounds = true
+        layer?.borderWidth = 1
+        layer?.borderColor = NSColor.white.withAlphaComponent(0.14).cgColor
+
+        stack.orientation = .vertical
+        stack.alignment = .leading
+        stack.spacing = 12
+        stack.detachesHiddenViews = true
+        stack.translatesAutoresizingMaskIntoConstraints = false
+        addSubview(stack)
+        NSLayoutConstraint.activate([
+            stack.leadingAnchor.constraint(equalTo: leadingAnchor, constant: 20),
+            stack.trailingAnchor.constraint(equalTo: trailingAnchor, constant: -20),
+            stack.topAnchor.constraint(equalTo: topAnchor, constant: 20),
+            stack.bottomAnchor.constraint(equalTo: bottomAnchor, constant: -20)
+        ])
+
+        addRow(makeHeader())
+        configureTextView(promptView, fontSize: 22)
+        promptView.delegate = self
+        promptView.isRichText = false
+        promptView.allowsUndo = true
+        promptView.setAccessibilityLabel("Quick question prompt")
+        promptView.onSubmit = { [weak self] in self?.submit() }
+        promptView.onToggle = { [weak self] in self?.delegate?.quickQuestionToggleRequested() }
+        let promptScroll = makeScrollView(documentView: promptView)
+        promptScroll.heightAnchor.constraint(equalToConstant: 64).isActive = true
+        addRow(promptScroll)
+
+        configureTextView(answerView, fontSize: 15)
+        answerView.isEditable = false
+        answerView.isSelectable = true
+        answerView.setAccessibilityLabel("Quick question answer")
+        answerView.linkTextAttributes = [.foregroundColor: NSColor.systemPurple, .underlineStyle: NSUnderlineStyle.single.rawValue]
+        answerScroll.drawsBackground = false
+        answerScroll.hasVerticalScroller = true
+        answerScroll.autohidesScrollers = true
+        answerScroll.documentView = answerView
+        answerScroll.heightAnchor.constraint(equalToConstant: 280).isActive = true
+        addRow(answerScroll)
+
+        statusLabel.font = .systemFont(ofSize: 12)
+        statusLabel.textColor = .secondaryLabelColor
+        statusLabel.maximumNumberOfLines = 3
+        addRow(statusLabel)
+        addRow(makeControls())
+        let hint = NSTextField(labelWithString: "Return to ask   ·   Shift+Return for a new line   ·   Esc to close")
+        hint.font = .systemFont(ofSize: 11)
+        hint.textColor = .secondaryLabelColor
+        addRow(hint)
+        update(SybilQuickQuestionPanelState(), shortcutAvailable: true)
+    }
+
+    required init?(coder: NSCoder) { fatalError("init(coder:) has not been implemented") }
+
+    func update(_ next: SybilQuickQuestionPanelState, shortcutAvailable: Bool) {
+        let previous = panelState
+        panelState = next
+        if promptView.string != next.prompt, !promptView.hasMarkedText() {
+            promptView.string = next.prompt
+            promptView.setSelectedRange(NSRange(location: (next.prompt as NSString).length, length: 0))
+        }
+        promptView.isEditable = !next.isBusy
+        promptView.needsDisplay = true
+        if previous.answer != next.answer {
+            let wasAtBottom = answerScroll.contentView.bounds.maxY >= answerView.bounds.maxY - 36
+            answerView.textStorage?.setAttributedString(Self.renderAnswer(next.answer))
+            if wasAtBottom { answerView.scrollToEndOfDocument(nil) }
+        }
+        answerScroll.isHidden = next.answer.isEmpty
+
+        if providerPopup.numberOfItems == 0 || previous.providers != next.providers {
+            providerPopup.removeAllItems()
+            for provider in next.providers {
+                providerPopup.addItem(withTitle: provider.title)
+                providerPopup.lastItem?.representedObject = provider.id
+            }
+        }
+        if let index = next.providers.firstIndex(where: { $0.id == next.provider }) {
+            providerPopup.selectItem(at: index)
+        }
+        if modelPopup.numberOfItems == 0 || previous.models != next.models || previous.model != next.model {
+            modelPopup.removeAllItems()
+            var models = next.models
+            if !next.model.isEmpty, !models.contains(next.model) { models.insert(next.model, at: 0) }
+            modelPopup.addItems(withTitles: models)
+            modelPopup.selectItem(withTitle: next.model)
+        }
+        providerPopup.isEnabled = next.isAuthenticated && !next.isBusy
+        modelPopup.isEnabled = next.isAuthenticated && !next.isBusy
+        convertButton.isEnabled = next.canConvert
+        sendButton.isEnabled = next.canSend
+        openAppButton.isHidden = next.isAuthenticated
+        convertButton.isHidden = !next.isAuthenticated
+        shortcutLabel.stringValue = shortcutAvailable ? "⌥ Space" : "Shortcut unavailable"
+        shortcutLabel.toolTip = shortcutAvailable ? "Option+Space toggles Quick Question" : "Another app may be using Option+Space. Open Quick Question from Sybil’s File menu."
+
+        let status: String
+        if let error = next.error {
+            status = error
+            statusLabel.textColor = .systemRed
+        } else {
+            statusLabel.textColor = .secondaryLabelColor
+            if next.isCheckingSession {
+                status = "Connecting to Sybil…"
+            } else if !next.isAuthenticated {
+                status = "Connect in Sybil before asking a question."
+            } else if next.isConverting {
+                status = "Opening in chat…"
+            } else if next.isSending {
+                status = next.toolSummaries.last ?? "Thinking…"
+            } else {
+                status = ""
+            }
+        }
+        statusLabel.stringValue = status
+        statusLabel.isHidden = status.isEmpty
+    }
+
+    func preparePromptForPresentation() {
+        // Select only when invoked, never on streamed updates or normal edits.
+        promptView.selectAll(nil)
+    }
+
+    func textDidChange(_ notification: Notification) {
+        guard !panelState.isBusy else { return }
+        promptView.needsDisplay = true
+        delegate?.quickQuestionPromptChanged(promptView.string)
+    }
+
+    private func addRow(_ view: NSView) {
+        stack.addArrangedSubview(view)
+        view.widthAnchor.constraint(equalTo: stack.widthAnchor).isActive = true
+    }
+
+    private func makeHeader() -> NSView {
+        let icon = NSImageView(image: NSImage(systemSymbolName: "sparkles", accessibilityDescription: nil)!)
+        icon.contentTintColor = .systemPurple
+        icon.widthAnchor.constraint(equalToConstant: 18).isActive = true
+        let title = NSTextField(labelWithString: "Quick Question")
+        title.font = .systemFont(ofSize: 14, weight: .semibold)
+        shortcutLabel.font = .monospacedSystemFont(ofSize: 11, weight: .medium)
+        shortcutLabel.textColor = .secondaryLabelColor
+        let close = NSButton(image: NSImage(systemSymbolName: "xmark", accessibilityDescription: "Close Quick Question")!, target: self, action: #selector(closePanel))
+        close.isBordered = false
+        close.toolTip = "Close (Esc)"
+        close.setAccessibilityLabel("Close Quick Question")
+        close.widthAnchor.constraint(equalToConstant: 24).isActive = true
+        let row = NSStackView(views: [icon, title, NSView(), shortcutLabel, close])
+        row.spacing = 8
+        row.alignment = .centerY
+        row.heightAnchor.constraint(equalToConstant: 24).isActive = true
+        return row
+    }
+
+    private func makeControls() -> NSView {
+        providerPopup.target = self
+        providerPopup.action = #selector(changeProvider)
+        providerPopup.setAccessibilityLabel("Quick question provider")
+        providerPopup.widthAnchor.constraint(equalToConstant: 120).isActive = true
+        modelPopup.target = self
+        modelPopup.action = #selector(changeModel)
+        modelPopup.setAccessibilityLabel("Quick question model")
+        modelPopup.widthAnchor.constraint(lessThanOrEqualToConstant: 230).isActive = true
+        modelPopup.setContentCompressionResistancePriority(.defaultLow, for: .horizontal)
+        convertButton.target = self
+        convertButton.action = #selector(convertToChat)
+        convertButton.bezelStyle = .rounded
+        openAppButton.target = self
+        openAppButton.action = #selector(openApp)
+        openAppButton.bezelStyle = .rounded
+        sendButton.image = NSImage(systemSymbolName: "arrow.up", accessibilityDescription: "Ask Quick Question")
+        sendButton.imagePosition = .imageOnly
+        sendButton.bezelStyle = .circular
+        sendButton.contentTintColor = .systemPurple
+        sendButton.target = self
+        sendButton.action = #selector(submit)
+        sendButton.setAccessibilityLabel("Ask Quick Question")
+        sendButton.toolTip = "Ask (Return)"
+        sendButton.widthAnchor.constraint(equalToConstant: 32).isActive = true
+        let row = NSStackView(views: [providerPopup, modelPopup, NSView(), openAppButton, convertButton, sendButton])
+        row.spacing = 8
+        row.alignment = .centerY
+        row.detachesHiddenViews = true
+        row.heightAnchor.constraint(equalToConstant: 32).isActive = true
+        return row
+    }
+
+    private func configureTextView(_ view: NSTextView, fontSize: CGFloat) {
+        view.drawsBackground = false
+        view.textColor = .labelColor
+        view.insertionPointColor = .labelColor
+        view.font = .systemFont(ofSize: fontSize)
+        view.textContainerInset = NSSize(width: 0, height: 4)
+        view.isHorizontallyResizable = false
+        view.isVerticallyResizable = true
+        view.autoresizingMask = [.width]
+        view.textContainer?.widthTracksTextView = true
+        view.textContainer?.lineFragmentPadding = 0
+    }
+
+    private func makeScrollView(documentView: NSView) -> NSScrollView {
+        let scroll = NSScrollView()
+        scroll.drawsBackground = false
+        scroll.hasVerticalScroller = true
+        scroll.autohidesScrollers = true
+        scroll.documentView = documentView
+        return scroll
+    }
+
+    private static func renderAnswer(_ text: String) -> NSAttributedString {
+        let parsed = (try? AttributedString(markdown: text, options: .init(interpretedSyntax: .inlineOnlyPreservingWhitespace))) ?? AttributedString(text)
+        let rendered = NSMutableAttributedString(attributedString: NSAttributedString(parsed))
+        let paragraph = NSMutableParagraphStyle()
+        paragraph.lineSpacing = 4
+        rendered.addAttributes([.foregroundColor: NSColor.labelColor, .paragraphStyle: paragraph], range: NSRange(location: 0, length: rendered.length))
+        for run in parsed.runs {
+            let intent = run.inlinePresentationIntent ?? []
+            var font = intent.contains(.code) ? NSFont.monospacedSystemFont(ofSize: 14, weight: .regular) : NSFont.systemFont(ofSize: 15)
+            if intent.contains(.stronglyEmphasized) { font = NSFontManager.shared.convert(font, toHaveTrait: .boldFontMask) }
+            if intent.contains(.emphasized) { font = NSFontManager.shared.convert(font, toHaveTrait: .italicFontMask) }
+            rendered.addAttribute(.font, value: font, range: NSRange(run.range, in: parsed))
+        }
+        return rendered
+    }
+
+    @objc private func closePanel() { onDismiss?() }
+    @objc private func changeProvider() {
+        guard let provider = providerPopup.selectedItem?.representedObject as? String else { return }
+        delegate?.quickQuestionProviderChanged(provider)
+    }
+    @objc private func changeModel() {
+        guard let model = modelPopup.titleOfSelectedItem else { return }
+        delegate?.quickQuestionModelChanged(model)
+    }
+    @objc private func convertToChat() { delegate?.quickQuestionConvertRequested() }
+    @objc private func openApp() { delegate?.quickQuestionOpenAppRequested() }
+    @objc private func submit() {
+        guard panelState.canSend, !promptView.hasMarkedText() else { return }
+        delegate?.quickQuestionSubmitRequested()
+    }
+}
+
+@MainActor
+final class QuickQuestionPromptView: NSTextView {
+    var onSubmit: (() -> Void)?
+    var onToggle: (() -> Void)?
+
+    override func draw(_ dirtyRect: NSRect) {
+        super.draw(dirtyRect)
+        guard string.isEmpty else { return }
+        ("Ask anything…" as NSString).draw(
+            at: NSPoint(x: textContainerInset.width, y: textContainerInset.height),
+            withAttributes: [.font: font ?? NSFont.systemFont(ofSize: 22), .foregroundColor: NSColor.placeholderTextColor]
+        )
+    }
+
+    override func keyDown(with event: NSEvent) {
+        let modifiers = event.modifierFlags.intersection([.command, .control, .option, .shift])
+        if event.keyCode == 49, modifiers == .option {
+            if !event.isARepeat { onToggle?() }
+            return
+        }
+        if (event.keyCode == 36 || event.keyCode == 76), modifiers.isEmpty, !hasMarkedText() {
+            if !event.isARepeat { onSubmit?() }
+            return
+        }
+        // Let the text input system handle Shift+Return and IME confirmation.
+        super.keyDown(with: event)
+    }
+}

ios/Apps/SybilMacQuickQuestion/project.yml

@@ -0,0 +1,25 @@
+targets:
+  SybilMacQuickQuestion:
+    type: bundle
+    platform: macOS
+    deploymentTarget: "15.0"
+    sources:
+      - Sources
+      - ../../Packages/Sybil/Sources/Sybil/SybilMacQuickQuestionBridge.swift
+    dependencies:
+      - sdk: AppKit.framework
+      - sdk: Carbon.framework
+    settings:
+      base:
+        PRODUCT_BUNDLE_IDENTIFIER: net.buzzert.sybil2.quick-question-panel
+        PRODUCT_NAME: SybilMacQuickQuestion
+        PRODUCT_MODULE_NAME: SybilMacQuickQuestion
+        DEVELOPMENT_TEAM: DQQH5H6GBD
+        CODE_SIGN_STYLE: Automatic
+        SWIFT_VERSION: 6.0
+        SUPPORTS_MACCATALYST: NO
+        GENERATE_INFOPLIST_FILE: YES
+        INFOPLIST_KEY_CFBundleExecutable: $(EXECUTABLE_NAME)
+        INFOPLIST_KEY_NSPrincipalClass: SybilMacQuickQuestionPlugin
+        MACH_O_TYPE: mh_bundle
+        SKIP_INSTALL: YES

ios/Packages/Sybil/Sources/Sybil/SplitView.swift

@@ -78,6 +78,7 @@ public struct SplitView: View {
         .font(.sybil(.body))
         .preferredColorScheme(.dark)
         .focusedSceneValue(\.sybilKeyboardActions, keyboardActions)
+        #if !targetEnvironment(macCatalyst)
         .sheet(isPresented: $isQuickQuestionPresented, onDismiss: handleQuickQuestionDismissed) {
             SybilQuickQuestionView(
                 viewModel: viewModel,
@@ -85,7 +86,11 @@ public struct SplitView: View {
             )
             .presentationDragIndicator(.visible)
         }
+        #endif
         .task {
+            #if targetEnvironment(macCatalyst)
+            SybilMacQuickQuestionController.shared.attach(viewModel)
+            #endif
             await viewModel.bootstrap()
             presentPendingQuickQuestionIfPossible()
         }
@@ -107,6 +112,9 @@ public struct SplitView: View {
                 shouldRefreshOnForeground = true
                 viewModel.markAppInactiveForNetwork()
             case .active:
+                #if targetEnvironment(macCatalyst)
+                SybilMacQuickQuestionController.shared.attach(viewModel)
+                #endif
                 viewModel.markAppActiveForNetwork()
                 guard shouldRefreshOnForeground, horizontalSizeClass != .compact else {
                     return
@@ -151,8 +159,13 @@ public struct SplitView: View {
         }
 
         hasPendingQuickQuestionPresentation = false
+        #if targetEnvironment(macCatalyst)
+        SybilMacQuickQuestionController.shared.attach(viewModel)
+        SybilMacQuickQuestionController.shared.show()
+        #else
         quickQuestionFocusRequest += 1
         isQuickQuestionPresented = true
+        #endif
     }
 
     private func handleQuickQuestionDismissed() {
@@ -161,23 +174,57 @@ public struct SplitView: View {
 }
 
 public struct SybilCommands: Commands {
+    public static let workspaceWindowID = "sybil-workspace"
+
     @FocusedValue(\.sybilKeyboardActions) private var keyboardActions
+    #if targetEnvironment(macCatalyst)
+    @Environment(\.openWindow) private var openWindow
+    @ObservedObject private var windowCommands = SybilMacWindowCommands.shared
+    #endif
 
     public init() {}
 
     public var body: some Commands {
         CommandGroup(replacing: .newItem) {
             Button("New Chat") {
+                #if targetEnvironment(macCatalyst)
+                windowCommands.newChatOrWindow(
+                    newChat: keyboardActions?.newChat,
+                    openWindow: openNewWindow
+                )
+                #else
                 keyboardActions?.newChat()
+                #endif
             }
             .keyboardShortcut("n", modifiers: .command)
+            #if targetEnvironment(macCatalyst)
+            .disabled(!windowCommands.canStartNewChat(hasFocusedActions: keyboardActions != nil))
+            #else
             .disabled(keyboardActions == nil)
+            #endif
+
+            #if targetEnvironment(macCatalyst)
+            Button("New Window", action: openNewWindow)
+                .keyboardShortcut("n", modifiers: [.command, .shift])
+            #endif
 
             Button("New Search") {
                 keyboardActions?.newSearch()
             }
+            #if targetEnvironment(macCatalyst)
+            .keyboardShortcut("n", modifiers: [.command, .option])
+            #else
             .keyboardShortcut("n", modifiers: [.command, .shift])
+            #endif
             .disabled(keyboardActions == nil)
+
+            #if targetEnvironment(macCatalyst)
+            Divider()
+            Button("Quick Question") {
+                SybilMacQuickQuestionController.shared.toggle()
+            }
+            .keyboardShortcut(.space, modifiers: .option)
+            #endif
         }
 
         CommandMenu("Conversation") {
@@ -194,6 +241,13 @@ public struct SybilCommands: Commands {
             .disabled(keyboardActions == nil)
         }
     }
+    #if targetEnvironment(macCatalyst)
+    private func openNewWindow() {
+        // Targeting a WindowGroup without a value creates a fresh scene every
+        // time, even when another workspace window is already open.
+        openWindow(id: Self.workspaceWindowID)
+    }
+    #endif
 }
 
 private struct SybilKeyboardActions {

ios/Packages/Sybil/Sources/Sybil/SybilMacQuickQuestionBridge.swift

@@ -0,0 +1,71 @@
+import Foundation
+
+// This Foundation-only contract is compiled into both the Catalyst client and the
+// native macOS bundle. Only Objective-C-compatible values cross the bundle boundary.
+@MainActor
+@objc(SybilQuickQuestionPanelBridging)
+protocol SybilQuickQuestionPanelBridging: NSObjectProtocol {
+    init()
+    var isVisible: Bool { get }
+    func start(delegate: any SybilQuickQuestionPanelDelegate) -> Int32
+    func updateState(_ data: Data)
+    func show()
+    func hide()
+    func activateForQuickQuestion()
+    func activateMainWindow()
+    func stop()
+}
+
+@MainActor
+@objc(SybilQuickQuestionPanelDelegate)
+protocol SybilQuickQuestionPanelDelegate: NSObjectProtocol {
+    func quickQuestionToggleRequested()
+    func quickQuestionPromptChanged(_ prompt: String)
+    func quickQuestionSubmitRequested()
+    func quickQuestionProviderChanged(_ provider: String)
+    func quickQuestionModelChanged(_ model: String)
+    func quickQuestionConvertRequested()
+    func quickQuestionOpenAppRequested()
+    func quickQuestionPanelDismissed()
+}
+
+struct SybilQuickQuestionPanelState: Codable, Equatable, Sendable {
+    struct ProviderOption: Codable, Equatable, Sendable {
+        var id: String
+        var title: String
+    }
+
+    var prompt = ""
+    var answer = ""
+    var toolSummaries: [String] = []
+    var provider = ""
+    var providers: [ProviderOption] = []
+    var model = ""
+    var models: [String] = []
+    var isSending = false
+    var isConverting = false
+    var canSend = false
+    var canConvert = false
+    var isAuthenticated = false
+    var isCheckingSession = true
+    var error: String?
+
+    var isBusy: Bool { isSending || isConverting }
+    var hasResponse: Bool { !answer.isEmpty || !toolSummaries.isEmpty || isSending || error != nil }
+}
+
+// Carbon can deliver multiple presses while a key is held. Consume one toggle
+// per press/release pair, without suppressing a second deliberate press.
+struct SybilQuickQuestionHotKeyState {
+    private var isPressed = false
+
+    mutating func shouldToggle(isKeyDown: Bool) -> Bool {
+        if !isKeyDown {
+            isPressed = false
+            return false
+        }
+        guard !isPressed else { return false }
+        isPressed = true
+        return true
+    }
+}

ios/Packages/Sybil/Sources/Sybil/SybilMacQuickQuestionController.swift

@@ -0,0 +1,257 @@
+#if targetEnvironment(macCatalyst)
+import Combine
+import Foundation
+import Observation
+import UIKit
+
+@MainActor
+public final class SybilMacQuickQuestionController: NSObject, SybilQuickQuestionPanelDelegate {
+    public static let shared = SybilMacQuickQuestionController()
+
+    private var pluginBundle: Bundle?
+    private var bridge: (any SybilQuickQuestionPanelBridging)?
+    private var viewModel: SybilViewModel?
+    private var observationGeneration = 0
+    private var isPresentationRequested = false
+    private var activationRequested = false
+    private var presentationTask: Task<Void, Never>?
+    private var foregroundObservation: AnyCancellable?
+    private var notificationCenter = NotificationCenter.default
+    private var isApplicationInForeground: @MainActor () -> Bool = {
+        UIApplication.shared.applicationState != .background
+    }
+
+    private override init() {
+        super.init()
+    }
+
+    // Inject foreground readiness as well as the panel so tests can exercise
+    // windowless activation without activating apps or showing real windows.
+    init(
+        bridge: any SybilQuickQuestionPanelBridging,
+        isApplicationInForeground: @escaping @MainActor () -> Bool = { true },
+        notificationCenter: NotificationCenter = NotificationCenter()
+    ) {
+        self.bridge = bridge
+        self.isApplicationInForeground = isApplicationInForeground
+        self.notificationCenter = notificationCenter
+        super.init()
+        _ = bridge.start(delegate: self)
+        observeForegroundTransitionsIfNeeded()
+    }
+
+    public func start() {
+        observeForegroundTransitionsIfNeeded()
+        guard bridge == nil else { return }
+        guard let url = Bundle.main.builtInPlugInsURL?.appendingPathComponent("SybilMacQuickQuestion.bundle"),
+              let bundle = Bundle(url: url)
+        else {
+            SybilLog.error(SybilLog.app, "The macOS Quick Question bundle is missing.")
+            return
+        }
+
+        do {
+            try bundle.loadAndReturnError()
+            guard let pluginClass = bundle.principalClass as? any SybilQuickQuestionPanelBridging.Type else {
+                SybilLog.error(SybilLog.app, "The macOS Quick Question bundle has an invalid principal class.")
+                return
+            }
+            let plugin = pluginClass.init()
+            pluginBundle = bundle
+            bridge = plugin
+            let status = plugin.start(delegate: self)
+            if status != 0 {
+                SybilLog.warning(SybilLog.app, "Option+Space could not be registered (status \(status)). Quick Question remains available in the app menu.")
+            }
+        } catch {
+            SybilLog.error(SybilLog.app, "Could not load the macOS Quick Question panel", error: error)
+        }
+    }
+
+    func attach(_ viewModel: SybilViewModel) {
+        guard self.viewModel !== viewModel else { return }
+        // A window becoming active must not replace an in-flight quick question.
+        if self.viewModel != nil,
+           isPresentationRequested || bridge?.isVisible == true || self.viewModel?.isQuickQuestionSending == true || self.viewModel?.isConvertingQuickQuestion == true {
+            return
+        }
+        self.viewModel = viewModel
+        if bridge?.isVisible == true { updateAndObserve() }
+    }
+
+    public func toggle() {
+        start()
+        if isPresentationRequested || bridge?.isVisible == true {
+            cancelPresentation()
+            bridge?.hide()
+        } else {
+            show()
+        }
+    }
+
+    public func show() {
+        start()
+        isPresentationRequested = true
+        schedulePresentationIfNeeded()
+    }
+
+    public func stop() {
+        cancelPresentation()
+        foregroundObservation = nil
+        viewModel?.cancelQuickQuestion()
+        bridge?.stop()
+        bridge = nil
+        // Keep the loaded bundle alive for the lifetime of its code.
+    }
+
+    private func observeForegroundTransitionsIfNeeded() {
+        guard foregroundObservation == nil else { return }
+        foregroundObservation = notificationCenter.publisher(for: UIApplication.willEnterForegroundNotification)
+            .merge(with: notificationCenter.publisher(for: UIApplication.didBecomeActiveNotification))
+            .sink { [weak self] _ in
+                Task { @MainActor [weak self] in
+                    self?.schedulePresentationIfNeeded()
+                }
+            }
+    }
+
+    private func schedulePresentationIfNeeded() {
+        guard isPresentationRequested, bridge?.isVisible != true, presentationTask == nil else { return }
+        // Leave the Carbon/NSApplication event callback before touching windows.
+        // AppKit activation is asynchronous; an arbitrary delay or NSApp.isActive
+        // is not a substitute for checking UIKit's foreground lifecycle state.
+        presentationTask = Task { @MainActor [weak self] in
+            guard let self, !Task.isCancelled else { return }
+            self.presentationTask = nil
+            guard self.isPresentationRequested else { return }
+            guard self.isApplicationInForeground() else {
+                guard !self.activationRequested else { return }
+                self.activationRequested = true
+                SybilLog.debug(SybilLog.ui, "Waiting for Catalyst foreground before showing Quick Question")
+                self.bridge?.activateForQuickQuestion()
+                // Also handle an activation that completes synchronously. If it
+                // has not completed, subsequent UIKit notifications resume us.
+                self.schedulePresentationIfNeeded()
+                return
+            }
+            self.activationRequested = false
+            self.updateAndObserve()
+            self.bridge?.show()
+        }
+    }
+
+    private func cancelPresentation() {
+        isPresentationRequested = false
+        activationRequested = false
+        presentationTask?.cancel()
+        presentationTask = nil
+        observationGeneration += 1
+    }
+
+    private func updateAndObserve() {
+        guard let bridge else { return }
+        observationGeneration += 1
+        let generation = observationGeneration
+        let state = withObservationTracking {
+            viewModel?.macQuickQuestionPanelState ?? SybilQuickQuestionPanelState()
+        } onChange: { [weak self] in
+            Task { @MainActor [weak self] in
+                guard let self, self.observationGeneration == generation, self.bridge?.isVisible == true else { return }
+                self.updateAndObserve()
+            }
+        }
+        do {
+            bridge.updateState(try JSONEncoder().encode(state))
+        } catch {
+            SybilLog.error(SybilLog.ui, "Could not update the macOS Quick Question panel", error: error)
+        }
+    }
+
+    func quickQuestionToggleRequested() {
+        toggle()
+    }
+
+    func quickQuestionPromptChanged(_ prompt: String) {
+        guard let viewModel, !viewModel.isQuickQuestionSending, !viewModel.isConvertingQuickQuestion else { return }
+        viewModel.updateQuickQuestionPrompt(prompt)
+        updateAndObserve()
+    }
+
+    func quickQuestionSubmitRequested() {
+        guard let viewModel, viewModel.isAuthenticated, !viewModel.isCheckingSession else { return }
+        viewModel.sendQuickQuestion()
+        updateAndObserve()
+    }
+
+    func quickQuestionProviderChanged(_ provider: String) {
+        guard let viewModel, let provider = Provider(rawValue: provider),
+              !viewModel.isQuickQuestionSending, !viewModel.isConvertingQuickQuestion else { return }
+        viewModel.setQuickQuestionProvider(provider)
+        updateAndObserve()
+    }
+
+    func quickQuestionModelChanged(_ model: String) {
+        guard let viewModel, !viewModel.isQuickQuestionSending, !viewModel.isConvertingQuickQuestion else { return }
+        viewModel.setQuickQuestionModel(model)
+        updateAndObserve()
+    }
+
+    func quickQuestionConvertRequested() {
+        guard let viewModel, viewModel.canConvertQuickQuestion else { return }
+        Task { @MainActor [weak self] in
+            guard let self else { return }
+            if await viewModel.convertQuickQuestionToChat() {
+                self.cancelPresentation()
+                self.openMainWindow()
+                self.bridge?.hide()
+            } else {
+                self.updateAndObserve()
+            }
+        }
+    }
+
+    func quickQuestionOpenAppRequested() {
+        cancelPresentation()
+        openMainWindow()
+        bridge?.hide()
+    }
+
+    private func openMainWindow() {
+        let session = UIApplication.shared.connectedScenes
+            .compactMap { $0 as? UIWindowScene }
+            .first?.session
+        UIApplication.shared.requestSceneSessionActivation(session, userActivity: nil, options: nil)
+        bridge?.activateMainWindow()
+    }
+
+    func quickQuestionPanelDismissed() {
+        // Toggling out preserves the draft and lets an answer finish. Reopening
+        // reads the latest state, without starting a new request.
+        cancelPresentation()
+    }
+}
+
+extension SybilViewModel {
+    var macQuickQuestionPanelState: SybilQuickQuestionPanelState {
+        SybilQuickQuestionPanelState(
+            prompt: quickQuestionPrompt,
+            answer: quickQuestionAnswerText,
+            toolSummaries: quickQuestionMessages.compactMap { message in
+                guard let metadata = message.toolCallMetadata else { return nil }
+                return metadata.summary ?? message.content
+            },
+            provider: quickQuestionProvider.rawValue,
+            providers: providerOptions.map { .init(id: $0.rawValue, title: $0.displayName) },
+            model: quickQuestionModel,
+            models: quickQuestionProviderModelOptions,
+            isSending: isQuickQuestionSending,
+            isConverting: isConvertingQuickQuestion,
+            canSend: isAuthenticated && !isCheckingSession && canSendQuickQuestion,
+            canConvert: canConvertQuickQuestion,
+            isAuthenticated: isAuthenticated,
+            isCheckingSession: isCheckingSession,
+            error: quickQuestionError
+        )
+    }
+}
+#endif

ios/Packages/Sybil/Sources/Sybil/SybilMacWindowCommands.swift

@@ -0,0 +1,37 @@
+#if targetEnvironment(macCatalyst)
+import Combine
+
+// Scene lifetime is independent of focused commands: a connected window may
+// still be authenticating, inactive, or minimized. The native Quick Question
+// panel is not a workspace scene and does not count as an open window here.
+@MainActor
+public final class SybilMacWindowCommands: ObservableObject {
+    public static let shared = SybilMacWindowCommands()
+
+    @Published private var connectedWindowIDs: Set<String> = []
+
+    init() {}
+
+    var hasOpenWindows: Bool { !connectedWindowIDs.isEmpty }
+
+    public func windowConnected(sessionID: String) {
+        connectedWindowIDs.insert(sessionID)
+    }
+
+    public func windowDisconnected(sessionID: String) {
+        connectedWindowIDs.remove(sessionID)
+    }
+
+    func canStartNewChat(hasFocusedActions: Bool) -> Bool {
+        !hasOpenWindows || hasFocusedActions
+    }
+
+    func newChatOrWindow(newChat: (() -> Void)?, openWindow: () -> Void) {
+        if hasOpenWindows {
+            newChat?()
+        } else {
+            openWindow()
+        }
+    }
+}
+#endif

ios/Packages/Sybil/Sources/Sybil/SybilModels.swift

@@ -154,6 +154,8 @@ public struct ChatAttachment: Codable, Hashable, Identifiable, Sendable {
 public struct ChatSummary: Codable, Identifiable, Hashable, Sendable {
     public var id: String
     public var title: String?
+    public var parentChatId: String? = nil
+    public var titleGenerationPending = false
     public var createdAt: Date
     public var updatedAt: Date
     public var starred = false
@@ -164,6 +166,39 @@ public struct ChatSummary: Codable, Identifiable, Hashable, Sendable {
     public var lastUsedModel: String?
 }
 
+extension ChatSummary {
+    private enum CodingKeys: String, CodingKey {
+        case id
+        case title
+        case parentChatId
+        case titleGenerationPending
+        case createdAt
+        case updatedAt
+        case starred
+        case starredAt
+        case initiatedProvider
+        case initiatedModel
+        case lastUsedProvider
+        case lastUsedModel
+    }
+
+    public init(from decoder: Decoder) throws {
+        let container = try decoder.container(keyedBy: CodingKeys.self)
+        id = try container.decode(String.self, forKey: .id)
+        title = try container.decodeIfPresent(String.self, forKey: .title)
+        parentChatId = try container.decodeIfPresent(String.self, forKey: .parentChatId)
+        titleGenerationPending = try container.decodeIfPresent(Bool.self, forKey: .titleGenerationPending) ?? false
+        createdAt = try container.decode(Date.self, forKey: .createdAt)
+        updatedAt = try container.decode(Date.self, forKey: .updatedAt)
+        starred = try container.decodeIfPresent(Bool.self, forKey: .starred) ?? false
+        starredAt = try container.decodeIfPresent(Date.self, forKey: .starredAt)
+        initiatedProvider = try container.decodeIfPresent(Provider.self, forKey: .initiatedProvider)
+        initiatedModel = try container.decodeIfPresent(String.self, forKey: .initiatedModel)
+        lastUsedProvider = try container.decodeIfPresent(Provider.self, forKey: .lastUsedProvider)
+        lastUsedModel = try container.decodeIfPresent(String.self, forKey: .lastUsedModel)
+    }
+}
+
 public struct SearchSummary: Codable, Identifiable, Hashable, Sendable {
     public var id: String
     public var title: String?
@@ -184,6 +219,8 @@ public struct WorkspaceItem: Codable, Identifiable, Hashable, Sendable {
     public var id: String
     public var title: String?
     public var query: String?
+    public var parentChatId: String? = nil
+    public var titleGenerationPending = false
     public var createdAt: Date
     public var updatedAt: Date
     public var starred = false
@@ -198,6 +235,8 @@ public struct WorkspaceItem: Codable, Identifiable, Hashable, Sendable {
         self.id = chat.id
         self.title = chat.title
         self.query = nil
+        self.parentChatId = chat.parentChatId
+        self.titleGenerationPending = chat.titleGenerationPending
         self.createdAt = chat.createdAt
         self.updatedAt = chat.updatedAt
         self.starred = chat.starred
@@ -213,6 +252,8 @@ public struct WorkspaceItem: Codable, Identifiable, Hashable, Sendable {
         self.id = search.id
         self.title = search.title
         self.query = search.query
+        self.parentChatId = nil
+        self.titleGenerationPending = false
         self.createdAt = search.createdAt
         self.updatedAt = search.updatedAt
         self.starred = search.starred
@@ -228,6 +269,8 @@ public struct WorkspaceItem: Codable, Identifiable, Hashable, Sendable {
         return ChatSummary(
             id: id,
             title: title,
+            parentChatId: parentChatId,
+            titleGenerationPending: titleGenerationPending,
             createdAt: createdAt,
             updatedAt: updatedAt,
             starred: starred,
@@ -253,6 +296,43 @@ public struct WorkspaceItem: Codable, Identifiable, Hashable, Sendable {
     }
 }
 
+extension WorkspaceItem {
+    private enum CodingKeys: String, CodingKey {
+        case type
+        case id
+        case title
+        case query
+        case parentChatId
+        case titleGenerationPending
+        case createdAt
+        case updatedAt
+        case starred
+        case starredAt
+        case initiatedProvider
+        case initiatedModel
+        case lastUsedProvider
+        case lastUsedModel
+    }
+
+    public init(from decoder: Decoder) throws {
+        let container = try decoder.container(keyedBy: CodingKeys.self)
+        type = try container.decode(WorkspaceItemType.self, forKey: .type)
+        id = try container.decode(String.self, forKey: .id)
+        title = try container.decodeIfPresent(String.self, forKey: .title)
+        query = try container.decodeIfPresent(String.self, forKey: .query)
+        parentChatId = try container.decodeIfPresent(String.self, forKey: .parentChatId)
+        titleGenerationPending = try container.decodeIfPresent(Bool.self, forKey: .titleGenerationPending) ?? false
+        createdAt = try container.decode(Date.self, forKey: .createdAt)
+        updatedAt = try container.decode(Date.self, forKey: .updatedAt)
+        starred = try container.decodeIfPresent(Bool.self, forKey: .starred) ?? false
+        starredAt = try container.decodeIfPresent(Date.self, forKey: .starredAt)
+        initiatedProvider = try container.decodeIfPresent(Provider.self, forKey: .initiatedProvider)
+        initiatedModel = try container.decodeIfPresent(String.self, forKey: .initiatedModel)
+        lastUsedProvider = try container.decodeIfPresent(Provider.self, forKey: .lastUsedProvider)
+        lastUsedModel = try container.decodeIfPresent(String.self, forKey: .lastUsedModel)
+    }
+}
+
 public struct Message: Codable, Identifiable, Hashable, Sendable {
     public var id: String
     public var createdAt: Date
@@ -391,6 +471,8 @@ public enum JSONValue: Codable, Hashable, Sendable {
 public struct ChatDetail: Codable, Identifiable, Hashable, Sendable {
     public var id: String
     public var title: String?
+    public var parentChatId: String? = nil
+    public var titleGenerationPending = false
     public var createdAt: Date
     public var updatedAt: Date
     public var starred = false
@@ -402,6 +484,41 @@ public struct ChatDetail: Codable, Identifiable, Hashable, Sendable {
     public var messages: [Message]
 }
 
+extension ChatDetail {
+    private enum CodingKeys: String, CodingKey {
+        case id
+        case title
+        case parentChatId
+        case titleGenerationPending
+        case createdAt
+        case updatedAt
+        case starred
+        case starredAt
+        case initiatedProvider
+        case initiatedModel
+        case lastUsedProvider
+        case lastUsedModel
+        case messages
+    }
+
+    public init(from decoder: Decoder) throws {
+        let container = try decoder.container(keyedBy: CodingKeys.self)
+        id = try container.decode(String.self, forKey: .id)
+        title = try container.decodeIfPresent(String.self, forKey: .title)
+        parentChatId = try container.decodeIfPresent(String.self, forKey: .parentChatId)
+        titleGenerationPending = try container.decodeIfPresent(Bool.self, forKey: .titleGenerationPending) ?? false
+        createdAt = try container.decode(Date.self, forKey: .createdAt)
+        updatedAt = try container.decode(Date.self, forKey: .updatedAt)
+        starred = try container.decodeIfPresent(Bool.self, forKey: .starred) ?? false
+        starredAt = try container.decodeIfPresent(Date.self, forKey: .starredAt)
+        initiatedProvider = try container.decodeIfPresent(Provider.self, forKey: .initiatedProvider)
+        initiatedModel = try container.decodeIfPresent(String.self, forKey: .initiatedModel)
+        lastUsedProvider = try container.decodeIfPresent(Provider.self, forKey: .lastUsedProvider)
+        lastUsedModel = try container.decodeIfPresent(String.self, forKey: .lastUsedModel)
+        messages = try container.decode([Message].self, forKey: .messages)
+    }
+}
+
 public struct SearchResultItem: Codable, Identifiable, Hashable, Sendable {
     public var id: String
     public var createdAt: Date

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

@@ -8,6 +8,7 @@ struct SybilQuickQuestionView: View {
 
     @Environment(\.dismiss) private var dismiss
     @FocusState private var promptFocused: Bool
+    @State private var promptSelection: TextSelection?
 
     private var hasAnswerContent: Bool {
         !viewModel.quickQuestionMessages.isEmpty || viewModel.quickQuestionError != nil
@@ -36,6 +37,8 @@ struct SybilQuickQuestionView: View {
                 return
             }
             promptFocused = true
+            let prompt = viewModel.quickQuestionPrompt
+            promptSelection = TextSelection(range: prompt.startIndex..<prompt.endIndex)
         }
     }
 
@@ -94,6 +97,7 @@ struct SybilQuickQuestionView: View {
                         get: { viewModel.quickQuestionPrompt },
                         set: { viewModel.updateQuickQuestionPrompt($0) }
                     ),
+                    selection: $promptSelection,
                     axis: .vertical
                 )
                 .focused($promptFocused)

ios/Packages/Sybil/Sources/Sybil/SybilReturnKeySubmission.swift

@@ -0,0 +1,35 @@
+import SwiftUI
+
+// A vertical TextField treats Return as editing, not form submission. Handle
+// unmodified Return explicitly on Mac, leaving Shift+Return and other modified
+// keys to the native text field. iOS keeps its software-keyboard behavior.
+@MainActor
+enum SybilReturnKeySubmission {
+    static func handle(
+        phase: KeyPress.Phases,
+        modifiers: EventModifiers,
+        submit: () -> Void
+    ) -> KeyPress.Result {
+        guard modifiers.intersection([.shift, .command, .control, .option]).isEmpty else {
+            return .ignored
+        }
+        if phase == .down {
+            submit()
+        }
+        // Consume autorepeat without submitting or inserting a newline.
+        return .handled
+    }
+}
+
+extension View {
+    @ViewBuilder
+    func submitOnMacReturn(_ submit: @escaping () -> Void) -> some View {
+        #if targetEnvironment(macCatalyst)
+        onKeyPress(keys: [.return, KeyEquivalent("\u{3}")], phases: [.down, .repeat]) { press in
+            SybilReturnKeySubmission.handle(phase: press.phase, modifiers: press.modifiers, submit: submit)
+        }
+        #else
+        self
+        #endif
+    }
+}

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

@@ -406,14 +406,17 @@ final class SybilViewModel {
                 } else {
                     initiatedLabel = nil
                 }
+                let starOwner = item.parentChatId.flatMap { parentChatID in
+                    workspaceItems.first(where: { $0.type == .chat && $0.id == parentChatID })
+                } ?? item
 
                 return SidebarItem(
                     selection: .chat(item.id),
                     kind: .chat,
                     title: chatTitle(title: item.title, messages: nil),
                     updatedAt: item.updatedAt,
-                    starred: item.starred,
-                    starredAt: item.starredAt,
+                    starred: starOwner.starred,
+                    starredAt: starOwner.starredAt,
                     initiatedLabel: initiatedLabel,
                     isRunning: isChatRowRunning(item.id)
                 )
@@ -633,9 +636,12 @@ final class SybilViewModel {
         }
 
         cancelQuickQuestion()
+        // Lock submission before the task starts, including repeated Return
+        // events delivered in the same main-actor turn.
+        isQuickQuestionSending = true
         let selectedProvider = quickQuestionProvider
         let task = Task { [weak self] in
-            guard let self else {
+            guard let self, !Task.isCancelled else {
                 return
             }
             await self.runQuickQuestion(prompt: content, provider: selectedProvider, model: selectedModel)
@@ -687,6 +693,8 @@ final class SybilViewModel {
             selectedChat = ChatDetail(
                 id: chat.id,
                 title: chat.title,
+                parentChatId: chat.parentChatId,
+                titleGenerationPending: chat.titleGenerationPending,
                 createdAt: chat.createdAt,
                 updatedAt: chat.updatedAt,
                 starred: chat.starred,
@@ -896,7 +904,8 @@ final class SybilViewModel {
                 let client = try client()
                 switch selection {
                 case let .chat(chatID):
-                    let updated = try await client.updateChatStar(chatID: chatID, starred: starred)
+                    let rootChatID = chatFamilyRootID(for: chatID)
+                    let updated = try await client.updateChatStar(chatID: rootChatID, starred: starred)
                     applyChatSummary(updated, moveToFront: false)
                 case let .search(searchID):
                     let updated = try await client.updateSearchStar(searchID: searchID, starred: starred)
@@ -1454,6 +1463,8 @@ final class SybilViewModel {
 
         if selectedChat?.id == chat.id {
             selectedChat?.title = chat.title
+            selectedChat?.parentChatId = chat.parentChatId
+            selectedChat?.titleGenerationPending = chat.titleGenerationPending
             selectedChat?.updatedAt = chat.updatedAt
             selectedChat?.starred = chat.starred
             selectedChat?.starredAt = chat.starredAt
@@ -1505,6 +1516,19 @@ final class SybilViewModel {
         workspaceItems.insert(item, at: 0)
     }
 
+    private func chatFamilyRootID(for chatID: String) -> String {
+        if let selectedChat, selectedChat.id == chatID, let parentChatID = selectedChat.parentChatId {
+            return parentChatID
+        }
+        if let parentChatID = chats.first(where: { $0.id == chatID })?.parentChatId {
+            return parentChatID
+        }
+        if let parentChatID = workspaceItems.first(where: { $0.type == .chat && $0.id == chatID })?.parentChatId {
+            return parentChatID
+        }
+        return chatID
+    }
+
     private func attachToVisibleActiveRunIfNeeded() {
         guard draftKind == nil else {
             return
@@ -1854,6 +1878,8 @@ final class SybilViewModel {
                 selectedChat = ChatDetail(
                     id: created.id,
                     title: created.title,
+                    parentChatId: created.parentChatId,
+                    titleGenerationPending: created.titleGenerationPending,
                     createdAt: created.createdAt,
                     updatedAt: created.updatedAt,
                     starred: created.starred,
@@ -1912,7 +1938,7 @@ final class SybilViewModel {
         let streamLifecycleGeneration = appLifecycleGeneration
         let streamStartedWhileInactive = !isAppActive
 
-        if isUntitledChat(chatID: chatID, detail: currentSelectedChat) {
+        if shouldRequestChatTitle(baseChat) {
             Task { [weak self] in
                 guard let self else { return }
                 do {
@@ -2623,20 +2649,10 @@ final class SybilViewModel {
         )
     }
 
-    private func isUntitledChat(chatID: String, detail: ChatDetail?) -> Bool {
-        if let detail, detail.id == chatID {
-            if let title = detail.title?.trimmingCharacters(in: .whitespacesAndNewlines), !title.isEmpty {
-                return false
-            }
+    private func shouldRequestChatTitle(_ chat: ChatDetail) -> Bool {
+        if chat.titleGenerationPending {
             return true
         }
-
-        if let summary = chats.first(where: { $0.id == chatID }) {
-            if let title = summary.title?.trimmingCharacters(in: .whitespacesAndNewlines), !title.isEmpty {
-                return false
-            }
-        }
-
-        return true
+        return chat.title?.trimmingCharacters(in: .whitespacesAndNewlines).isEmpty ?? true
     }
 }

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

@@ -601,6 +601,7 @@ struct SybilWorkspaceView: View {
                 .onSubmit {
                     submitComposer()
                 }
+                .submitOnMacReturn(submitComposer)
                 .padding(.horizontal, 12)
                 .padding(.vertical, 10)
                 .background(

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

@@ -1,6 +1,10 @@
 import CoreGraphics
 import Foundation
+import SwiftUI
 import Testing
+#if targetEnvironment(macCatalyst)
+import UIKit
+#endif
 @testable import Sybil
 
 private struct MockClientCallSnapshot: Sendable {
@@ -10,7 +14,10 @@ private struct MockClientCallSnapshot: Sendable {
     var createChat = 0
     var getChat = 0
     var updateChatTitle = 0
+    var suggestChatTitle = 0
     var updateChatStar = 0
+    var lastUpdateChatStarID: String?
+    var lastUpdateChatStarred: Bool?
     var updateSearchStar = 0
     var getSearch = 0
     var getActiveRuns = 0
@@ -36,6 +43,7 @@ private actor MockSybilClient: SybilAPIClienting {
     private let searchDetails: [String: SearchDetail]
     private let createChatResponse: ChatSummary?
     private let updateChatTitleResponses: [String: ChatSummary]
+    private let suggestChatTitleResponses: [String: ChatSummary]
     private let updateChatStarResponses: [String: ChatSummary]
     private let updateSearchStarResponses: [String: SearchSummary]
     private let activeRunsResponse: ActiveRunsResponse
@@ -64,6 +72,7 @@ private actor MockSybilClient: SybilAPIClienting {
         searchDetails: [String: SearchDetail] = [:],
         createChatResponse: ChatSummary? = nil,
         updateChatTitleResponses: [String: ChatSummary] = [:],
+        suggestChatTitleResponses: [String: ChatSummary] = [:],
         updateChatStarResponses: [String: ChatSummary] = [:],
         updateSearchStarResponses: [String: SearchSummary] = [:],
         activeRunsResponse: ActiveRunsResponse = ActiveRunsResponse(),
@@ -76,6 +85,7 @@ private actor MockSybilClient: SybilAPIClienting {
         self.searchDetails = searchDetails
         self.createChatResponse = createChatResponse
         self.updateChatTitleResponses = updateChatTitleResponses
+        self.suggestChatTitleResponses = suggestChatTitleResponses
         self.updateChatStarResponses = updateChatStarResponses
         self.updateSearchStarResponses = updateSearchStarResponses
         self.activeRunsResponse = activeRunsResponse
@@ -204,6 +214,8 @@ private actor MockSybilClient: SybilAPIClienting {
 
     func updateChatStar(chatID: String, starred: Bool) async throws -> ChatSummary {
         snapshot.updateChatStar += 1
+        snapshot.lastUpdateChatStarID = chatID
+        snapshot.lastUpdateChatStarred = starred
         guard let summary = updateChatStarResponses[chatID] else {
             throw UnexpectedClientCall()
         }
@@ -215,7 +227,11 @@ private actor MockSybilClient: SybilAPIClienting {
     }
 
     func suggestChatTitle(chatID: String, content: String) async throws -> ChatSummary {
-        throw UnexpectedClientCall()
+        snapshot.suggestChatTitle += 1
+        guard let summary = suggestChatTitleResponses[chatID] else {
+            throw UnexpectedClientCall()
+        }
+        return summary
     }
 
     func listSearches() async throws -> [SearchSummary] {
@@ -420,6 +436,46 @@ private func makeToolCallMessage(id: String, date: Date, summary: String = "Ran
     )
 }
 
+@Test func chatForkMetadataDecodesBackwardCompatiblyAndSurvivesWorkspaceConversions() throws {
+    let decoder = JSONDecoder()
+    let legacySummary = try decoder.decode(
+        ChatSummary.self,
+        from: Data(#"{"id":"legacy-chat","title":"Legacy","createdAt":0,"updatedAt":1}"#.utf8)
+    )
+    let legacyWorkspaceItem = try decoder.decode(
+        WorkspaceItem.self,
+        from: Data(#"{"type":"chat","id":"legacy-chat","title":"Legacy","createdAt":0,"updatedAt":1}"#.utf8)
+    )
+    let legacyDetail = try decoder.decode(
+        ChatDetail.self,
+        from: Data(#"{"id":"legacy-chat","title":"Legacy","createdAt":0,"updatedAt":1,"messages":[]}"#.utf8)
+    )
+    let forkDetail = try decoder.decode(
+        ChatDetail.self,
+        from: Data(#"{"id":"fork-chat","title":"Fork of Legacy","parentChatId":"root-chat","titleGenerationPending":true,"createdAt":0,"updatedAt":1,"messages":[]}"#.utf8)
+    )
+
+    #expect(legacySummary.parentChatId == nil)
+    #expect(!legacySummary.titleGenerationPending)
+    #expect(legacyWorkspaceItem.parentChatId == nil)
+    #expect(!legacyWorkspaceItem.titleGenerationPending)
+    #expect(legacyDetail.parentChatId == nil)
+    #expect(!legacyDetail.titleGenerationPending)
+    #expect(forkDetail.parentChatId == "root-chat")
+    #expect(forkDetail.titleGenerationPending)
+
+    var fork = legacySummary
+    fork.parentChatId = "root-chat"
+    fork.titleGenerationPending = true
+
+    let workspaceItem = WorkspaceItem(chat: fork)
+    let restoredSummary = try #require(workspaceItem.chatSummary)
+    #expect(workspaceItem.parentChatId == "root-chat")
+    #expect(workspaceItem.titleGenerationPending)
+    #expect(restoredSummary.parentChatId == "root-chat")
+    #expect(restoredSummary.titleGenerationPending)
+}
+
 @Test func transcriptRenderItemsGroupAdjacentToolCalls() async throws {
     let date = Date(timeIntervalSince1970: 1_700_000_000)
     let user = Message(id: "user-1", createdAt: date, role: .user, content: "Search this", name: nil)
@@ -567,18 +623,16 @@ private func makeToolCallMessage(id: String, date: Date, summary: String = "Ran
 @MainActor
 @Test func renameChatUpdatesSidebarAndSelectedTranscriptTitle() async throws {
     let date = Date(timeIntervalSince1970: 1_700_000_150)
-    let original = makeChatSummary(id: "chat-rename", date: date)
-    let renamed = ChatSummary(
-        id: "chat-rename",
-        title: "Renamed chat",
-        createdAt: date,
-        updatedAt: date.addingTimeInterval(60),
-        initiatedProvider: .openai,
-        initiatedModel: "gpt-4.1-mini",
-        lastUsedProvider: .openai,
-        lastUsedModel: "gpt-4.1-mini"
-    )
-    let detail = makeChatDetail(id: "chat-rename", date: date, body: "existing transcript")
+    var original = makeChatSummary(id: "chat-rename", date: date)
+    original.parentChatId = "root-chat"
+    original.titleGenerationPending = true
+    var renamed = original
+    renamed.title = "Renamed chat"
+    renamed.titleGenerationPending = false
+    renamed.updatedAt = date.addingTimeInterval(60)
+    var detail = makeChatDetail(id: "chat-rename", date: date, body: "existing transcript")
+    detail.parentChatId = original.parentChatId
+    detail.titleGenerationPending = original.titleGenerationPending
     let client = MockSybilClient(
         chatsResponse: [original],
         updateChatTitleResponses: ["chat-rename": renamed]
@@ -596,7 +650,13 @@ private func makeToolCallMessage(id: String, date: Date, summary: String = "Ran
     let snapshot = await client.currentSnapshot()
     #expect(snapshot.updateChatTitle == 1)
     #expect(viewModel.sidebarItems.first?.title == "Renamed chat")
+    #expect(viewModel.chats.first?.parentChatId == "root-chat")
+    #expect(viewModel.chats.first?.titleGenerationPending == false)
+    #expect(viewModel.workspaceItems.first?.parentChatId == "root-chat")
+    #expect(viewModel.workspaceItems.first?.titleGenerationPending == false)
     #expect(viewModel.selectedChat?.title == "Renamed chat")
+    #expect(viewModel.selectedChat?.parentChatId == "root-chat")
+    #expect(viewModel.selectedChat?.titleGenerationPending == false)
     #expect(viewModel.errorMessage == nil)
 }
 
@@ -635,6 +695,54 @@ private func makeToolCallMessage(id: String, date: Date, summary: String = "Ran
     #expect(viewModel.sidebarItems.first(where: { $0.selection == .search("search-star") })?.starred == true)
 }
 
+@MainActor
+@Test func unstarringForkTargetsRootWithoutReplacingSelectedChild() async throws {
+    let date = Date(timeIntervalSince1970: 1_700_000_180)
+    var root = makeChatSummary(id: "chat-root", date: date)
+    root.starred = true
+    root.starredAt = date.addingTimeInterval(5)
+
+    var child = makeChatSummary(id: "chat-child", date: date.addingTimeInterval(1))
+    child.parentChatId = root.id
+    child.titleGenerationPending = true
+
+    var childDetail = makeChatDetail(id: child.id, date: date, body: "forked transcript")
+    childDetail.title = child.title
+    childDetail.parentChatId = root.id
+    childDetail.titleGenerationPending = true
+
+    var unstarredRoot = root
+    unstarredRoot.starred = false
+    unstarredRoot.starredAt = nil
+
+    let client = MockSybilClient(
+        chatsResponse: [root, child],
+        updateChatStarResponses: [root.id: unstarredRoot]
+    )
+    let viewModel = SybilViewModel(settings: testSettings(named: #function)) { _ in client }
+    viewModel.isAuthenticated = true
+    viewModel.isCheckingSession = false
+    viewModel.chats = [root, child]
+    viewModel.workspaceItems = [WorkspaceItem(chat: root), WorkspaceItem(chat: child)]
+    viewModel.selectedItem = .chat(child.id)
+    viewModel.selectedChat = childDetail
+
+    #expect(viewModel.sidebarItems.first(where: { $0.selection == .chat(child.id) })?.starred == true)
+
+    await viewModel.setItemStarred(.chat(child.id), starred: false)
+
+    let snapshot = await client.currentSnapshot()
+    #expect(snapshot.updateChatStar == 1)
+    #expect(snapshot.lastUpdateChatStarID == root.id)
+    #expect(snapshot.lastUpdateChatStarred == false)
+    #expect(viewModel.chats.first(where: { $0.id == root.id })?.starred == false)
+    #expect(viewModel.chats.first(where: { $0.id == child.id }) == child)
+    #expect(viewModel.sidebarItems.first(where: { $0.selection == .chat(child.id) })?.starred == false)
+    #expect(viewModel.selectedItem == .chat(child.id))
+    #expect(viewModel.selectedChat == childDetail)
+    #expect(viewModel.errorMessage == nil)
+}
+
 @MainActor
 @Test func foregroundSearchRefreshReloadsSelectedSearch() async throws {
     let date = Date(timeIntervalSince1970: 1_700_000_200)
@@ -781,6 +889,142 @@ private func makeToolCallMessage(id: String, date: Date, summary: String = "Ran
     #expect(viewModel.chatBottomPinRequestID == initialPinRequestID + 1)
 }
 
+@MainActor
+@Test func firstPromptInPendingForkRequestsAndAppliesGeneratedTitle() async throws {
+    let date = Date(timeIntervalSince1970: 1_700_000_247)
+    var fork = makeChatSummary(id: "chat-fork", date: date)
+    fork.title = "Fork of Original chat"
+    fork.parentChatId = "root-chat"
+    fork.titleGenerationPending = true
+
+    var forkDetail = makeChatDetail(id: fork.id, date: date, body: "forked transcript")
+    forkDetail.title = fork.title
+    forkDetail.parentChatId = fork.parentChatId
+    forkDetail.titleGenerationPending = true
+
+    var titledFork = fork
+    titledFork.title = "Investigating the follow-up"
+    titledFork.titleGenerationPending = false
+    titledFork.updatedAt = date.addingTimeInterval(1)
+
+    var titledForkDetail = forkDetail
+    titledForkDetail.title = titledFork.title
+    titledForkDetail.titleGenerationPending = false
+    titledForkDetail.updatedAt = titledFork.updatedAt
+
+    let client = MockSybilClient(
+        chatsResponse: [titledFork],
+        chatDetails: [fork.id: titledForkDetail],
+        suggestChatTitleResponses: [fork.id: titledFork]
+    )
+    await client.setCompletionStreamEvents(
+        [.done(CompletionStreamDone(text: "Follow-up answer"))],
+        delayNanoseconds: 100_000_000
+    )
+
+    let viewModel = SybilViewModel(settings: testSettings(named: #function)) { _ in client }
+    viewModel.isAuthenticated = true
+    viewModel.isCheckingSession = false
+    viewModel.chats = [fork]
+    viewModel.workspaceItems = [WorkspaceItem(chat: fork)]
+    viewModel.selectedItem = .chat(fork.id)
+    viewModel.selectedChat = forkDetail
+    viewModel.composer = "Investigate this follow-up"
+
+    let sendTask = Task {
+        await viewModel.sendComposer()
+    }
+
+    for _ in 0..<20 {
+        let snapshot = await client.currentSnapshot()
+        if snapshot.suggestChatTitle == 1,
+           viewModel.selectedChat?.title == titledFork.title,
+           viewModel.selectedChat?.titleGenerationPending == false {
+            break
+        }
+        try await Task.sleep(nanoseconds: 5_000_000)
+    }
+
+    let titleSnapshot = await client.currentSnapshot()
+    #expect(titleSnapshot.suggestChatTitle == 1)
+    #expect(viewModel.chats.first?.title == titledFork.title)
+    #expect(viewModel.workspaceItems.first?.title == titledFork.title)
+    #expect(viewModel.selectedChat?.title == titledFork.title)
+    #expect(viewModel.selectedChat?.titleGenerationPending == false)
+
+    await sendTask.value
+}
+
+@MainActor
+@Test func composerReturnSubmitsOnceAndConsumesRepeats() {
+    var submissions = 0
+    let initial = SybilReturnKeySubmission.handle(phase: .down, modifiers: []) { submissions += 1 }
+    let repeated = SybilReturnKeySubmission.handle(phase: .repeat, modifiers: []) { submissions += 1 }
+    #expect(initial == .handled)
+    #expect(repeated == .handled)
+    #expect(submissions == 1)
+}
+
+@MainActor
+@Test func composerModifiedReturnPreservesNativeEditing() {
+    var submissions = 0
+    for modifiers: EventModifiers in [.shift, .command, .control, .option, [.shift, .command]] {
+        let result = SybilReturnKeySubmission.handle(phase: .down, modifiers: modifiers) { submissions += 1 }
+        #expect(result == .ignored)
+    }
+    #expect(submissions == 0)
+}
+
+@MainActor
+@Test func composerReturnStillSubmitsWithCapsLock() {
+    var submissions = 0
+    let result = SybilReturnKeySubmission.handle(phase: .down, modifiers: .capsLock) { submissions += 1 }
+    #expect(result == .handled)
+    #expect(submissions == 1)
+}
+
+@Test func quickQuestionHotKeyTogglesOncePerPress() {
+    var keyState = SybilQuickQuestionHotKeyState()
+    let keyDownEvents = [true, true, true, false, true, false, false, true]
+    let toggles = keyDownEvents.map { keyState.shouldToggle(isKeyDown: $0) }
+    #expect(toggles == [true, false, false, false, true, false, false, true])
+}
+
+@MainActor
+@Test func quickQuestionRejectsDuplicateSubmissionBeforeTaskStarts() async throws {
+    let client = MockSybilClient()
+    await client.setCompletionStreamEvents([.done(CompletionStreamDone(text: "One answer."))])
+    let viewModel = SybilViewModel(settings: testSettings(named: #function)) { _ in client }
+    viewModel.quickQuestionPrompt = "One question"
+
+    let first = viewModel.sendQuickQuestion()
+    let duplicate = viewModel.sendQuickQuestion()
+    #expect(first != nil)
+    #expect(duplicate == nil)
+    #expect(viewModel.isQuickQuestionSending)
+    await first?.value
+
+    let calls = await client.currentSnapshot()
+    #expect(calls.runCompletionStream == 1)
+    #expect(viewModel.quickQuestionAnswerText == "One answer.")
+    #expect(!viewModel.isQuickQuestionSending)
+}
+
+@MainActor
+@Test func quickQuestionCancelledBeforeTaskStartsDoesNotSend() async throws {
+    let client = MockSybilClient()
+    let viewModel = SybilViewModel(settings: testSettings(named: #function)) { _ in client }
+    viewModel.quickQuestionPrompt = "Do not send this"
+
+    let task = viewModel.sendQuickQuestion()
+    viewModel.cancelQuickQuestion()
+    await task?.value
+
+    let calls = await client.currentSnapshot()
+    #expect(calls.runCompletionStream == 0)
+    #expect(!viewModel.isQuickQuestionSending)
+}
+
 @MainActor
 @Test func quickQuestionRunsNonPersistentCompletionStream() async throws {
     let client = MockSybilClient()
@@ -1050,3 +1294,365 @@ private func makeToolCallMessage(id: String, date: Date, summary: String = "Ran
     #expect(BackSwipeMetrics.shouldComplete(offset: 24, velocityX: 800, width: width, isLatched: false))
     #expect(!BackSwipeMetrics.shouldComplete(offset: latchDistance + 1, velocityX: -800, width: width, isLatched: true))
 }
+
+#if targetEnvironment(macCatalyst)
+@MainActor
+@Test func macNewChatCommandOpensWindowWhenNoWorkspacesRemain() {
+    let commands = SybilMacWindowCommands()
+    var chats = 0
+    var windows = 0
+
+    #expect(commands.canStartNewChat(hasFocusedActions: false))
+    commands.newChatOrWindow(newChat: nil, openWindow: { windows += 1 })
+    // A focused value can briefly outlive a closing scene. It must not route
+    // Command+N back into a closed workspace.
+    commands.newChatOrWindow(newChat: { chats += 1 }, openWindow: { windows += 1 })
+    #expect(windows == 2)
+    #expect(chats == 0)
+}
+
+@MainActor
+@Test func macNewChatCommandUsesExistingWorkspace() {
+    let commands = SybilMacWindowCommands()
+    commands.windowConnected(sessionID: "first")
+    var chats = 0
+    var windows = 0
+
+    #expect(commands.canStartNewChat(hasFocusedActions: true))
+    commands.newChatOrWindow(newChat: { chats += 1 }, openWindow: { windows += 1 })
+    #expect(chats == 1)
+    #expect(windows == 0)
+}
+
+@MainActor
+@Test func macNewChatCommandDoesNotMistakeUnavailableActionsForNoWindows() {
+    let commands = SybilMacWindowCommands()
+    commands.windowConnected(sessionID: "authenticating")
+    var windows = 0
+
+    #expect(!commands.canStartNewChat(hasFocusedActions: false))
+    commands.newChatOrWindow(newChat: nil, openWindow: { windows += 1 })
+    #expect(windows == 0)
+}
+
+@MainActor
+@Test func macWindowCommandsTrackLastWindowClosureAndReconnection() {
+    let commands = SybilMacWindowCommands()
+    commands.windowConnected(sessionID: "first")
+    commands.windowConnected(sessionID: "first")
+    commands.windowConnected(sessionID: "second")
+    commands.windowDisconnected(sessionID: "first")
+    #expect(commands.hasOpenWindows)
+    commands.windowDisconnected(sessionID: "first")
+    #expect(commands.hasOpenWindows)
+    commands.windowDisconnected(sessionID: "second")
+    #expect(!commands.hasOpenWindows)
+    #expect(commands.canStartNewChat(hasFocusedActions: false))
+    commands.windowConnected(sessionID: "third")
+    #expect(commands.hasOpenWindows)
+    #expect(!commands.canStartNewChat(hasFocusedActions: false))
+}
+
+@MainActor
+private final class MockQuickQuestionPanel: NSObject, SybilQuickQuestionPanelBridging {
+    private weak var delegate: (any SybilQuickQuestionPanelDelegate)?
+    var isVisible = false
+    var state = SybilQuickQuestionPanelState()
+    var presentationCount = 0
+    var activationCount = 0
+    var stateUpdateCount = 0
+    var events: [String] = []
+    var onShow: (() -> Void)?
+
+    required override init() { super.init() }
+    func start(delegate: any SybilQuickQuestionPanelDelegate) -> Int32 {
+        self.delegate = delegate
+        return 0
+    }
+    func updateState(_ data: Data) {
+        state = try! JSONDecoder().decode(SybilQuickQuestionPanelState.self, from: data)
+        stateUpdateCount += 1
+        events.append("update")
+    }
+    func show() {
+        onShow?()
+        isVisible = true
+        presentationCount += 1
+        events.append("show")
+    }
+    func hide() {
+        isVisible = false
+        delegate?.quickQuestionPanelDismissed()
+    }
+    func activateForQuickQuestion() {
+        activationCount += 1
+        events.append("activate")
+    }
+    func activateMainWindow() {}
+    func stop() { hide() }
+}
+
+@MainActor
+private func waitForQuickQuestion(_ condition: @MainActor () -> Bool) async throws {
+    for _ in 0..<100 {
+        if condition() { return }
+        try await Task.sleep(for: .milliseconds(2))
+    }
+    try #require(condition())
+}
+
+@MainActor
+private final class MockQuickQuestionLifecycle {
+    var isForeground = false
+    let notifications = NotificationCenter()
+
+    func notify(_ name: Notification.Name) {
+        notifications.post(name: name, object: nil)
+    }
+}
+
+@MainActor
+@Test func macQuickQuestionWaitsForUIKitForegroundBeforeOpeningPanel() async throws {
+    let lifecycle = MockQuickQuestionLifecycle()
+    let panel = MockQuickQuestionPanel()
+    let viewModel = SybilViewModel(settings: testSettings(named: #function)) { _ in MockSybilClient() }
+    viewModel.quickQuestionPrompt = "Original prompt"
+    let controller = SybilMacQuickQuestionController(
+        bridge: panel,
+        isApplicationInForeground: { lifecycle.isForeground },
+        notificationCenter: lifecycle.notifications
+    )
+    defer { controller.stop() }
+    controller.attach(viewModel)
+    panel.onShow = { #expect(lifecycle.isForeground) }
+
+    controller.toggle()
+    // Never create/order a window inline in the hotkey's event callback.
+    #expect(panel.presentationCount == 0)
+    #expect(panel.activationCount == 0)
+    try await waitForQuickQuestion { panel.activationCount == 1 }
+    #expect(panel.stateUpdateCount == 0)
+    #expect(!panel.isVisible)
+
+    // "Will enter" is not proof of readiness: UIKit can still be backgrounded.
+    lifecycle.notify(UIApplication.willEnterForegroundNotification)
+    try await Task.sleep(for: .milliseconds(10))
+    #expect(panel.activationCount == 1)
+    #expect(panel.presentationCount == 0)
+    #expect(panel.stateUpdateCount == 0)
+
+    viewModel.quickQuestionPrompt = "The latest prompt while waiting"
+    lifecycle.isForeground = true
+    lifecycle.notify(UIApplication.didBecomeActiveNotification)
+    try await waitForQuickQuestion { panel.isVisible }
+    #expect(panel.events == ["activate", "update", "show"])
+    #expect(panel.state.prompt == "The latest prompt while waiting")
+}
+
+@MainActor
+@Test func macQuickQuestionSecondToggleCancelsPendingActivation() async throws {
+    let lifecycle = MockQuickQuestionLifecycle()
+    let panel = MockQuickQuestionPanel()
+    let controller = SybilMacQuickQuestionController(
+        bridge: panel,
+        isApplicationInForeground: { lifecycle.isForeground },
+        notificationCenter: lifecycle.notifications
+    )
+    defer { controller.stop() }
+    controller.toggle()
+    try await waitForQuickQuestion { panel.activationCount == 1 }
+    controller.toggle()
+
+    lifecycle.isForeground = true
+    lifecycle.notify(UIApplication.didBecomeActiveNotification)
+    try await Task.sleep(for: .milliseconds(10))
+    #expect(!panel.isVisible)
+    #expect(panel.presentationCount == 0)
+    #expect(panel.stateUpdateCount == 0)
+
+    controller.toggle()
+    try await waitForQuickQuestion { panel.isVisible }
+    #expect(panel.presentationCount == 1)
+    #expect(panel.activationCount == 1)
+}
+
+@MainActor
+@Test func macQuickQuestionRapidTogglesKeepOnlyLatestPresentation() async throws {
+    let lifecycle = MockQuickQuestionLifecycle()
+    lifecycle.isForeground = true
+    let panel = MockQuickQuestionPanel()
+    let controller = SybilMacQuickQuestionController(
+        bridge: panel,
+        isApplicationInForeground: { lifecycle.isForeground },
+        notificationCenter: lifecycle.notifications
+    )
+    defer { controller.stop() }
+    controller.toggle()
+    controller.toggle()
+    controller.toggle()
+    #expect(panel.presentationCount == 0)
+    try await waitForQuickQuestion { panel.isVisible }
+    #expect(panel.presentationCount == 1)
+    #expect(panel.activationCount == 0)
+
+    // Lifecycle notifications must not present/select the prompt a second time.
+    lifecycle.notify(UIApplication.willEnterForegroundNotification)
+    lifecycle.notify(UIApplication.didBecomeActiveNotification)
+    try await Task.sleep(for: .milliseconds(10))
+    #expect(panel.presentationCount == 1)
+}
+
+@MainActor
+@Test func macQuickQuestionStopCancelsPendingPresentation() async throws {
+    let lifecycle = MockQuickQuestionLifecycle()
+    let panel = MockQuickQuestionPanel()
+    let controller = SybilMacQuickQuestionController(
+        bridge: panel,
+        isApplicationInForeground: { lifecycle.isForeground },
+        notificationCenter: lifecycle.notifications
+    )
+    controller.show()
+    try await waitForQuickQuestion { panel.activationCount == 1 }
+    controller.stop()
+    lifecycle.isForeground = true
+    lifecycle.notify(UIApplication.didBecomeActiveNotification)
+    try await Task.sleep(for: .milliseconds(10))
+    #expect(panel.presentationCount == 0)
+    #expect(panel.stateUpdateCount == 0)
+}
+
+@MainActor
+@Test func macQuickQuestionRechecksForegroundAfterLeavingHotKeyCallback() async throws {
+    let lifecycle = MockQuickQuestionLifecycle()
+    lifecycle.isForeground = true
+    let panel = MockQuickQuestionPanel()
+    let controller = SybilMacQuickQuestionController(
+        bridge: panel,
+        isApplicationInForeground: { lifecycle.isForeground },
+        notificationCenter: lifecycle.notifications
+    )
+    defer { controller.stop() }
+    controller.show()
+    lifecycle.isForeground = false
+    try await waitForQuickQuestion { panel.activationCount == 1 }
+    #expect(!panel.isVisible)
+    #expect(panel.stateUpdateCount == 0)
+    lifecycle.isForeground = true
+    lifecycle.notify(UIApplication.didBecomeActiveNotification)
+    try await waitForQuickQuestion { panel.isVisible }
+    #expect(panel.presentationCount == 1)
+}
+
+@MainActor
+@Test func macQuickQuestionTogglePreservesDraftAndUsesLatestAnswer() async throws {
+    let client = MockSybilClient()
+    let viewModel = SybilViewModel(settings: testSettings(named: #function)) { _ in client }
+    viewModel.isAuthenticated = true
+    viewModel.isCheckingSession = false
+    viewModel.quickQuestionPrompt = "Keep this draft"
+    let panel = MockQuickQuestionPanel()
+    let controller = SybilMacQuickQuestionController(bridge: panel)
+    controller.attach(viewModel)
+
+    controller.toggle()
+    try await waitForQuickQuestion { panel.isVisible }
+    #expect(panel.isVisible)
+    #expect(panel.state.prompt == "Keep this draft")
+    #expect(panel.state.canSend)
+    controller.toggle()
+    #expect(!panel.isVisible)
+
+    viewModel.quickQuestionMessages = [
+        Message(id: "temp-assistant-quick-test", createdAt: Date(), role: .assistant, content: "An answer arrived while hidden.", name: nil)
+    ]
+    controller.toggle()
+    try await waitForQuickQuestion { panel.isVisible }
+    #expect(panel.isVisible)
+    #expect(panel.presentationCount == 2)
+    #expect(panel.state.prompt == "Keep this draft")
+    #expect(panel.state.answer == "An answer arrived while hidden.")
+    let calls = await client.currentSnapshot()
+    #expect(calls.runCompletionStream == 0)
+    controller.stop()
+}
+
+@MainActor
+@Test func macQuickQuestionObservesStreamingAndKeepsItsOwner() async throws {
+    let viewModel = SybilViewModel(settings: testSettings(named: #function)) { _ in MockSybilClient() }
+    viewModel.isAuthenticated = true
+    viewModel.isCheckingSession = false
+    viewModel.quickQuestionPrompt = "Original window"
+    let panel = MockQuickQuestionPanel()
+    let controller = SybilMacQuickQuestionController(bridge: panel)
+    controller.attach(viewModel)
+    controller.show()
+
+    let otherWindow = SybilViewModel(settings: testSettings(named: #function + "-other")) { _ in MockSybilClient() }
+    otherWindow.quickQuestionPrompt = "Other window"
+    controller.attach(otherWindow)
+    viewModel.quickQuestionMessages = [
+        Message(id: "temp-assistant-quick-test", createdAt: Date(), role: .assistant, content: "Streaming update", name: nil)
+    ]
+    for _ in 0..<30 {
+        if panel.state.answer == "Streaming update" { break }
+        try await Task.sleep(for: .milliseconds(5))
+    }
+    #expect(panel.state.answer == "Streaming update")
+    #expect(panel.state.prompt == "Original window")
+    controller.stop()
+}
+
+@MainActor
+@Test func macQuickQuestionRetainsStateAfterLastWorkspaceCloses() async throws {
+    let client = MockSybilClient()
+    var windowViewModel: SybilViewModel? = SybilViewModel(settings: testSettings(named: #function)) { _ in client }
+    windowViewModel?.isAuthenticated = true
+    windowViewModel?.isCheckingSession = false
+    windowViewModel?.quickQuestionPrompt = "A question from the closed window"
+    windowViewModel?.quickQuestionMessages = [
+        Message(id: "temp-assistant-quick-windowless", createdAt: Date(), role: .assistant, content: "Keep this answer too.", name: nil)
+    ]
+    let panel = MockQuickQuestionPanel()
+    let controller = SybilMacQuickQuestionController(bridge: panel)
+    controller.attach(try #require(windowViewModel))
+
+    // Releasing the workspace must not release the global shortcut's model.
+    windowViewModel = nil
+    controller.toggle()
+    try await waitForQuickQuestion { panel.isVisible }
+    #expect(panel.isVisible)
+    #expect(panel.state.prompt == "A question from the closed window")
+    #expect(panel.state.answer == "Keep this answer too.")
+    controller.toggle()
+    #expect(!panel.isVisible)
+    controller.toggle()
+    try await waitForQuickQuestion { panel.isVisible }
+    #expect(panel.presentationCount == 2)
+    #expect(panel.state.canSend)
+    let calls = await client.currentSnapshot()
+    #expect(calls.runCompletionStream == 0)
+    controller.stop()
+}
+
+@MainActor
+@Test func macQuickQuestionCannotSubmitBeforeAuthentication() async throws {
+    let client = MockSybilClient()
+    let viewModel = SybilViewModel(settings: testSettings(named: #function)) { _ in client }
+    viewModel.isAuthenticated = false
+    viewModel.isCheckingSession = false
+    let panel = MockQuickQuestionPanel()
+    let controller = SybilMacQuickQuestionController(bridge: panel)
+    controller.attach(viewModel)
+    controller.show()
+    try await waitForQuickQuestion { panel.isVisible }
+    controller.quickQuestionPromptChanged("A signed-out question")
+    controller.quickQuestionSubmitRequested()
+
+    #expect(!panel.state.canSend)
+    #expect(panel.state.prompt == "A signed-out question")
+    #expect(!viewModel.isQuickQuestionSending)
+    let calls = await client.currentSnapshot()
+    #expect(calls.runCompletionStream == 0)
+    controller.stop()
+}
+#endif

ios/README.md

@@ -0,0 +1,76 @@
+# Sybil for iOS and Mac Catalyst
+
+Run `just run` for the iPhone simulator, or `just run-mac` for Mac Catalyst.
+`just build-mac` builds without launching the Mac app. Both regenerate the Xcode
+project from `project.yml`. The Mac recipes use ad-hoc signing for local development;
+release/archive signing settings are unchanged.
+
+## Quick Question on macOS
+
+While the Catalyst app is running, **Option+Space** toggles a floating Quick
+Question panel, including over other applications. The prompt is focused as soon
+as it opens, with any existing prompt selected so typing replaces it. The same
+select-on-open behavior applies to Quick Question on iPhone and iPad.
+**Return** submits; **Shift+Return** inserts a new line. **Escape**, a
+second **Option+Space**, the close button, or clicking outside dismisses it.
+Hiding the panel preserves the draft and answer and lets an in-flight answer finish.
+**Open in Chat** saves the question and answer in the regular workspace.
+
+The regular Mac chat/search composer uses the same Return/Shift+Return rules.
+Holding Return does not repeatedly submit. The iOS software keyboard is unchanged.
+
+Closing the last Mac window leaves Sybil running, so Option+Space still works.
+Use **Sybil → Quit Sybil** or **Command+Q** to quit the application. The Catalyst
+build opts out of automatic termination, and the native shortcut service holds a
+matching automatic-termination activity until it stops. No hidden keep-alive
+window or sleep-preventing activity is used. Mac scene support also allows the
+workspace to reopen after its last window is closed.
+
+When Catalyst is backgrounded, opening Quick Question first requests app
+activation and waits for UIKit to enter the foreground before creating or ordering
+the native panel. Presentation is deferred out of the hotkey event callback.
+Pressing Option+Space again cancels a pending presentation. Dismissing a panel
+that required activation returns focus to the previous app; explicitly opening
+the workspace keeps focus in Sybil.
+
+On Mac, **Command+N** starts a new chat in the focused workspace, or opens a new
+workspace window when none are open. **Command+Shift+N** always opens a new window,
+including while signed out. **Command+Option+N** starts a new search; iOS retains
+its existing Command+Shift+N search shortcut.
+
+The shortcut is also shown under **File → Quick Question**. If another application
+already owns Option+Space, the panel reports that the shortcut is unavailable;
+the menu item can still be clicked. No Accessibility or Input Monitoring grant is
+needed for the registered hotkey.
+
+The native AppKit panel and Carbon hotkey live in `Apps/SybilMacQuickQuestion`,
+a macOS bundle embedded only for the Mac Catalyst destination. Catalyst loads it
+through the Foundation-only `SybilMacQuickQuestionBridge` contract. Requests,
+provider/model preferences, streaming, and conversion to chat remain in the
+existing `SybilViewModel`; there is no separate backend or API contract. The panel
+uses AppKit controls rather than trying to load the macOS SwiftUI runtime into a
+Catalyst process.
+
+The iPhone/iPad app keeps its existing Quick Question sheet and Home Screen quick
+action, and does not build or embed the macOS helper.
+
+## Verification
+
+- `just test`: existing Swift package tests on the iPhone simulator.
+- From `Packages/Sybil`, run `xcodebuild test -scheme Sybil -destination 'platform=macOS,variant=Mac Catalyst' -parallel-testing-enabled NO` for package tests including the Catalyst panel controller.
+- For a manual Mac check, open the panel from another app, type immediately,
+  submit, hide/reopen during streaming, and verify Escape/outside-click dismissal
+  returns input to the previous app. Check a second display and a full-screen Space
+  when available.
+- Close every Mac window, invoke Option+Space, and verify the saved question and
+  answer remain available. Reopen the workspace from the panel, then explicitly
+  quit with Command+Q. Rebuild and relaunch after changing lifecycle plist keys.
+- In both Mac and iOS Quick Question, reopen an existing prompt and type to replace
+  it. In the Mac workspace, verify Return submits and Shift+Return adds a newline.
+- Check Command+N both with a workspace open and after closing every workspace.
+  Command+Shift+N must open another window even when one already exists, and
+  Command+Option+N must start a search without opening a window.
+- With all workspace windows closed, switch to another app and repeatedly open
+  and dismiss Quick Question, including two quick Option+Space presses while it
+  is opening. Check that no late panel appears after cancellation and that no
+  `UINSAppLifecycleStateRunningNoOpenWindows` assertion occurs.

ios/justfile

@@ -24,6 +24,12 @@ run: generate
   xcrun simctl install booted '{{derived_data}}/Build/Products/Debug-iphonesimulator/Sybil.app'
   xcrun simctl launch booted net.buzzert.sybil2
 
+build-mac: generate
+  xcodebuild -scheme Sybil -destination 'platform=macOS,variant=Mac Catalyst' -derivedDataPath '{{derived_data}}' CODE_SIGN_IDENTITY=- CODE_SIGNING_REQUIRED=NO
+
+run-mac: build-mac
+  open '{{derived_data}}/Build/Products/Debug-maccatalyst/Sybil.app'
+
 beta:
   fastlane ios beta
 

ios/project.yml

@@ -7,3 +7,4 @@ packages:
     path: Packages/Sybil
 include:
   - Apps/Sybil/project.yml
+  - Apps/SybilMacQuickQuestion/project.yml

scripts/devbox-start.sh

@@ -0,0 +1,90 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+ROOT="$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)"
+SESSION="${SYBIL_TMUX_SESSION:-sybil-dev}"
+LOG_DIR="$ROOT/.devbox/logs"
+PID_DIR="$ROOT/.devbox/pids"
+
+require_env() {
+  local name="$1"
+  if [[ -z "${!name:-}" ]]; then
+    echo "Missing required environment variable: $name" >&2
+    exit 1
+  fi
+}
+
+require_env OPENAI_API_KEY
+require_env EXA_API_KEY
+
+mkdir -p "$LOG_DIR" "$PID_DIR"
+
+export HOST="${HOST:-0.0.0.0}"
+export PORT="${PORT:-8787}"
+export DATABASE_URL="${DATABASE_URL:-file:$ROOT/server/dev.db}"
+
+echo "Installing server dependencies..."
+npm ci --prefix "$ROOT/server" --no-audit --no-fund
+
+echo "Installing web dependencies..."
+npm ci --prefix "$ROOT/web" --no-audit --no-fund
+
+if command -v tmux >/dev/null 2>&1; then
+  tmux kill-session -t "$SESSION" >/dev/null 2>&1 || true
+  tmux new-session -d -s "$SESSION" -n server -c "$ROOT/server" "sleep infinity"
+  tmux set-environment -t "$SESSION" OPENAI_API_KEY "$OPENAI_API_KEY"
+  tmux set-environment -t "$SESSION" EXA_API_KEY "$EXA_API_KEY"
+  tmux set-environment -t "$SESSION" HOST "$HOST"
+  tmux set-environment -t "$SESSION" PORT "$PORT"
+  tmux set-environment -t "$SESSION" DATABASE_URL "$DATABASE_URL"
+  if [[ -n "${BRIX_CLUSTER:-}" ]]; then
+    tmux set-environment -t "$SESSION" BRIX_CLUSTER "$BRIX_CLUSTER"
+  fi
+  for name in \
+    CHAT_CODEX_TOOL_ENABLED \
+    CHAT_CODEX_REMOTE_HOST \
+    CHAT_CODEX_REMOTE_USER \
+    CHAT_CODEX_REMOTE_PORT \
+    CHAT_CODEX_REMOTE_WORKDIR \
+    CHAT_CODEX_SSH_KEY_PATH \
+    CHAT_CODEX_SSH_PRIVATE_KEY_B64 \
+    CHAT_CODEX_EXEC_TIMEOUT_MS \
+    CHAT_SHELL_TOOL_ENABLED \
+    CHAT_SHELL_EXEC_TIMEOUT_MS; do
+    if [[ -n "${!name:-}" ]]; then
+      tmux set-environment -t "$SESSION" "$name" "${!name}"
+    fi
+  done
+  tmux respawn-pane -k -t "$SESSION:server.0" -c "$ROOT/server" "npm run dev"
+  tmux new-window -t "$SESSION" -n web -c "$ROOT/web" \
+    "npm run dev -- --host 0.0.0.0 --port 5173"
+  echo "Started Sybil in tmux session '$SESSION'."
+  echo "Server: http://127.0.0.1:8787"
+  echo "Web:    http://127.0.0.1:5173"
+  exit 0
+fi
+
+echo "tmux not found; starting background processes with nohup."
+
+if [[ -f "$PID_DIR/server.pid" ]]; then
+  kill "$(cat "$PID_DIR/server.pid")" >/dev/null 2>&1 || true
+fi
+if [[ -f "$PID_DIR/web.pid" ]]; then
+  kill "$(cat "$PID_DIR/web.pid")" >/dev/null 2>&1 || true
+fi
+
+(
+  cd "$ROOT/server"
+  exec env HOST="$HOST" PORT="$PORT" DATABASE_URL="$DATABASE_URL" npm run dev
+) >"$LOG_DIR/server.log" 2>&1 &
+echo "$!" >"$PID_DIR/server.pid"
+
+(
+  cd "$ROOT/web"
+  exec npm run dev -- --host 0.0.0.0 --port 5173
+) >"$LOG_DIR/web.log" 2>&1 &
+echo "$!" >"$PID_DIR/web.pid"
+
+echo "Started Sybil background processes."
+echo "Server log: $LOG_DIR/server.log"
+echo "Web log:    $LOG_DIR/web.log"

scripts/devbox-update.sh

@@ -0,0 +1,357 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+ROOT="$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)"
+REPO="${REPO:-Sybil-2}"
+WORKLOAD="${WORKLOAD:-sybil-dev}"
+CLUSTER="${CLUSTER:-viper}"
+NAMESPACE="${NAMESPACE:-buzzert}"
+QUOTA="${QUOTA:-research-api}"
+SECRET="${SECRET:-sybil-dev-env}"
+REMOTE_ROOT="${REMOTE_ROOT:-/root/code/$REPO}"
+INGRESS_PORT="${INGRESS_PORT:-5173}"
+CODEX_IMAGE="${CODEX_IMAGE:-openai.azurecr.io/rcall:crow-1b540b5e15f9-2026-01-22-2404-312}"
+CODEX_SERVICE="${CODEX_SERVICE:-sybil-codex-devbox}"
+CODEX_CONTAINER="${CODEX_CONTAINER:-codex-devbox}"
+CODEX_SSH_SECRET="${CODEX_SSH_SECRET:-sybil-codex-ssh}"
+CODEX_SSH_PORT="${CODEX_SSH_PORT:-2222}"
+CODEX_WORKDIR="${CODEX_WORKDIR:-/workspace/sybil-codex}"
+CODEX_SSH_KEY_PATH="${CODEX_SSH_KEY_PATH:-/run/secrets/sybil-codex-ssh/id_ed25519}"
+
+echo "Syncing $REPO to $WORKLOAD on $CLUSTER/$NAMESPACE..."
+brix create \
+  --project-root "$(dirname "$ROOT")" \
+  --path "$REPO=$ROOT" \
+  --repositories "$REPO" \
+  --include-untracked \
+  --reconcile-policy continuous \
+  -- \
+  "cluster=$CLUSTER" \
+  "namespace=$NAMESPACE" \
+  "name=$WORKLOAD" \
+  "pool.spec.quota=$QUOTA" \
+  "pool.spec.size.resource=cpu" \
+  "pool.spec.size.quantity=1" \
+  "pool.spec.priority=low"
+
+if [[ "$REPO" != "openai" ]]; then
+  if kubectl --context "$CLUSTER" -n "$NAMESPACE" get git "$WORKLOAD" -o json 2>/dev/null | jq -e '.spec.repositories.openai?' >/dev/null; then
+    kubectl --context "$CLUSTER" -n "$NAMESPACE" patch git "$WORKLOAD" --type=json -p='[{"op":"remove","path":"/spec/repositories/openai"}]'
+  fi
+fi
+
+if [[ -n "${OPENAI_API_KEY:-}" && -n "${EXA_API_KEY:-}" ]]; then
+  kubectl --context "$CLUSTER" -n "$NAMESPACE" create secret generic "$SECRET" \
+    --from-literal=OPENAI_API_KEY="$OPENAI_API_KEY" \
+    --from-literal=EXA_API_KEY="$EXA_API_KEY" \
+    --dry-run=client -o yaml | kubectl --context "$CLUSTER" -n "$NAMESPACE" apply -f -
+elif [[ -n "${OPENAI_API_KEY:-}" || -n "${EXA_API_KEY:-}" ]]; then
+  echo "Only one API key env var is set; keeping existing Kubernetes secret $SECRET." >&2
+fi
+
+if [[ "$(kubectl --context "$CLUSTER" -n "$NAMESPACE" get secret "$SECRET" -o name 2>/dev/null || true)" == "" ]]; then
+  echo "Secret $SECRET does not exist. Re-run with OPENAI_API_KEY and EXA_API_KEY set." >&2
+  exit 1
+fi
+
+if [[ "$(kubectl --context "$CLUSTER" -n "$NAMESPACE" get secret "$CODEX_SSH_SECRET" -o name 2>/dev/null || true)" == "" ]]; then
+  tmpdir="$(mktemp -d)"
+  trap 'rm -rf "$tmpdir"' EXIT
+  ssh-keygen -t ed25519 -N "" -C "sybil-codex@$WORKLOAD" -f "$tmpdir/id_ed25519" >/dev/null
+  kubectl --context "$CLUSTER" -n "$NAMESPACE" create secret generic "$CODEX_SSH_SECRET" \
+    --from-file=id_ed25519="$tmpdir/id_ed25519" \
+    --from-file=id_ed25519.pub="$tmpdir/id_ed25519.pub" \
+    --dry-run=client -o yaml | kubectl --context "$CLUSTER" -n "$NAMESPACE" apply -f -
+fi
+
+kubectl --context "$CLUSTER" -n "$NAMESPACE" patch secret "$SECRET" --type=merge -p "$(jq -n \
+  --arg host "$CODEX_SERVICE" \
+  --arg port "$CODEX_SSH_PORT" \
+  --arg workdir "$CODEX_WORKDIR" \
+  --arg keyPath "$CODEX_SSH_KEY_PATH" \
+  '{
+    stringData: {
+      CHAT_CODEX_TOOL_ENABLED: "true",
+      CHAT_CODEX_REMOTE_HOST: $host,
+      CHAT_CODEX_REMOTE_USER: "root",
+      CHAT_CODEX_REMOTE_PORT: $port,
+      CHAT_CODEX_REMOTE_WORKDIR: $workdir,
+      CHAT_CODEX_SSH_KEY_PATH: $keyPath,
+      CHAT_CODEX_EXEC_TIMEOUT_MS: "600000",
+      CHAT_SHELL_TOOL_ENABLED: "true"
+    }
+  }')"
+
+ensure_codex_deployment() {
+  kubectl --context "$CLUSTER" -n "$NAMESPACE" apply -f - <<KUBE_MANIFEST
+apiVersion: apps/v1
+kind: Deployment
+metadata:
+  name: $CODEX_SERVICE
+  labels:
+    app.kubernetes.io/name: $CODEX_SERVICE
+    app.kubernetes.io/part-of: sybil-dev
+spec:
+  replicas: 1
+  selector:
+    matchLabels:
+      app.kubernetes.io/name: $CODEX_SERVICE
+  template:
+    metadata:
+      labels:
+        app.kubernetes.io/name: $CODEX_SERVICE
+        app.kubernetes.io/part-of: sybil-dev
+    spec:
+      tolerations:
+        - key: openai.com/team
+          operator: Exists
+          effect: NoSchedule
+      containers:
+        - name: $CODEX_CONTAINER
+          image: $CODEX_IMAGE
+          imagePullPolicy: IfNotPresent
+          command: ["/bin/bash", "-lc"]
+          args:
+            - |
+              set -euo pipefail
+              export DEBIAN_FRONTEND=noninteractive
+              if ! command -v sshd >/dev/null 2>&1; then
+                apt-get update
+                apt-get install -y --no-install-recommends openssh-server ca-certificates git curl
+                rm -rf /var/lib/apt/lists/*
+              fi
+              if ! command -v codex >/dev/null 2>&1; then
+                npm install -g @openai/codex
+              fi
+              mkdir -p /run/sshd /root/.ssh "$CODEX_WORKDIR"
+              cp /run/secrets/sybil-codex-ssh/id_ed25519.pub /root/.ssh/authorized_keys
+              chmod 700 /root/.ssh
+              chmod 600 /root/.ssh/authorized_keys
+              {
+                if [[ -n "\${OPENAI_API_KEY:-}" ]]; then
+                  printf 'export OPENAI_API_KEY=%q\n' "\$OPENAI_API_KEY"
+                fi
+                if [[ -n "\${EXA_API_KEY:-}" ]]; then
+                  printf 'export EXA_API_KEY=%q\n' "\$EXA_API_KEY"
+                fi
+              } >/root/.sybil-codex-env
+              chmod 600 /root/.sybil-codex-env
+              cat >/usr/local/bin/sybil-codex-ssh-command <<'SSH_COMMAND'
+              #!/usr/bin/env bash
+              set -euo pipefail
+              if [[ -f /root/.sybil-codex-env ]]; then
+                source /root/.sybil-codex-env
+              fi
+              if [[ -n "\${SSH_ORIGINAL_COMMAND:-}" ]]; then
+                exec /bin/bash -lc "\$SSH_ORIGINAL_COMMAND"
+              fi
+              exec /bin/bash -l
+              SSH_COMMAND
+              chmod 700 /usr/local/bin/sybil-codex-ssh-command
+              ssh-keygen -A
+              cat >/tmp/sybil-codex-sshd_config <<SSHD_CONFIG
+              Port $CODEX_SSH_PORT
+              ListenAddress 0.0.0.0
+              PermitRootLogin prohibit-password
+              PasswordAuthentication no
+              PubkeyAuthentication yes
+              AcceptEnv OPENAI_API_KEY EXA_API_KEY
+              AuthorizedKeysFile .ssh/authorized_keys
+              PermitUserEnvironment no
+              ForceCommand /usr/local/bin/sybil-codex-ssh-command
+              AllowTcpForwarding no
+              X11Forwarding no
+              Subsystem sftp internal-sftp
+              PidFile /run/sshd/sybil-codex.pid
+              SSHD_CONFIG
+              exec \$(command -v sshd) -D -e -f /tmp/sybil-codex-sshd_config
+          ports:
+            - name: ssh
+              containerPort: $CODEX_SSH_PORT
+          envFrom:
+            - secretRef:
+                name: $SECRET
+          resources:
+            requests:
+              cpu: "1"
+              memory: 4Gi
+            limits:
+              cpu: "1"
+              memory: 4Gi
+          volumeMounts:
+            - name: sybil-codex-ssh
+              mountPath: /run/secrets/sybil-codex-ssh
+              readOnly: true
+            - name: sybil-codex-workspace
+              mountPath: /workspace
+      volumes:
+        - name: sybil-codex-ssh
+          secret:
+            secretName: $CODEX_SSH_SECRET
+            defaultMode: 384
+        - name: sybil-codex-workspace
+          emptyDir: {}
+---
+apiVersion: v1
+kind: Service
+metadata:
+  name: $CODEX_SERVICE
+  labels:
+    app.kubernetes.io/name: $CODEX_SERVICE
+    app.kubernetes.io/part-of: sybil-dev
+spec:
+  type: ClusterIP
+  selector:
+    app.kubernetes.io/name: $CODEX_SERVICE
+  ports:
+    - name: ssh
+      port: $CODEX_SSH_PORT
+      targetPort: ssh
+KUBE_MANIFEST
+
+  kubectl --context "$CLUSTER" -n "$NAMESPACE" rollout status "deployment/$CODEX_SERVICE" --timeout=300s
+}
+
+ensure_codex_deployment
+
+ensure_env_from() {
+  local resource="$1"
+  local name="$2"
+  local jsonpath="$3"
+  local patch_path="$4"
+  local existing_env_from
+
+  existing_env_from="$(kubectl --context "$CLUSTER" -n "$NAMESPACE" get "$resource" "$name" \
+    -o "jsonpath=$jsonpath" 2>/dev/null || true)"
+
+  if [[ "$existing_env_from" == *"$SECRET"* ]]; then
+    return
+  fi
+
+  local patch
+  if [[ -z "$existing_env_from" ]]; then
+    patch="[{\"op\":\"add\",\"path\":\"$patch_path\",\"value\":[{\"secretRef\":{\"name\":\"$SECRET\"}}]}]"
+  else
+    patch="[{\"op\":\"add\",\"path\":\"$patch_path/-\",\"value\":{\"secretRef\":{\"name\":\"$SECRET\"}}}]"
+  fi
+  kubectl --context "$CLUSTER" -n "$NAMESPACE" patch "$resource" "$name" --type=json -p "$patch"
+}
+
+ensure_env_from \
+  workload \
+  "$WORKLOAD" \
+  "{.spec.pools[0].template.template.spec.workers.template.spec.containers[0].envFrom}" \
+  "/spec/pools/0/template/template/spec/workers/template/spec/containers/0/envFrom"
+
+ensure_env_from \
+  pool \
+  "$WORKLOAD" \
+  "{.spec.workers.template.spec.containers[0].envFrom}" \
+  "/spec/workers/template/spec/containers/0/envFrom"
+
+codex_ssh_volume_json="$(jq -n --arg secret "$CODEX_SSH_SECRET" '{
+  name: "sybil-codex-ssh",
+  secret: {
+    secretName: $secret,
+    defaultMode: 384
+  }
+}')"
+codex_main_mount_json="$(jq -n '{name: "sybil-codex-ssh", mountPath: "/run/secrets/sybil-codex-ssh", readOnly: true}')"
+
+patch_pool_codex_mount() {
+  local pool_json containers volumes patch
+  pool_json="$(kubectl --context "$CLUSTER" -n "$NAMESPACE" get pool "$WORKLOAD" -o json)"
+  containers="$(jq \
+    --arg sidecarName "$CODEX_CONTAINER" \
+    --argjson mainMount "$codex_main_mount_json" \
+    '
+    def ensure_mount($mount):
+      .volumeMounts = (((.volumeMounts // []) | map(select(.name != $mount.name))) + [$mount]);
+    (.spec.workers.template.spec.containers // [])
+    | map(if .name == "main" then ensure_mount($mainMount) else . end)
+    | map(select(.name != $sidecarName))
+    ' <<<"$pool_json")"
+  volumes="$(jq \
+    --argjson sshVolume "$codex_ssh_volume_json" \
+    '
+    (.spec.workers.template.spec.volumes // [])
+    | map(select(.name != $sshVolume.name and .name != "sybil-codex-workspace"))
+    + [$sshVolume]
+    ' <<<"$pool_json")"
+  patch="$(jq -n --argjson containers "$containers" --argjson volumes "$volumes" '{
+    spec: {
+      workers: {
+        template: {
+          spec: {
+            containers: $containers,
+            volumes: $volumes
+          }
+        }
+      }
+    }
+  }')"
+  kubectl --context "$CLUSTER" -n "$NAMESPACE" patch pool "$WORKLOAD" --type=merge -p "$patch"
+}
+
+patch_workload_codex_mount() {
+  local workload_json pools patch
+  workload_json="$(kubectl --context "$CLUSTER" -n "$NAMESPACE" get workload "$WORKLOAD" -o json)"
+  pools="$(jq \
+    --arg groupName "$WORKLOAD" \
+    --arg sidecarName "$CODEX_CONTAINER" \
+    --argjson mainMount "$codex_main_mount_json" \
+    --argjson sshVolume "$codex_ssh_volume_json" \
+    '
+    def ensure_mount($mount):
+      .volumeMounts = (((.volumeMounts // []) | map(select(.name != $mount.name))) + [$mount]);
+    .spec.pools
+    | map(
+        if .groupName == $groupName then
+          .template.template.spec.workers.template.spec.containers =
+            ((.template.template.spec.workers.template.spec.containers // [])
+              | map(if .name == "main" then ensure_mount($mainMount) else . end)
+              | map(select(.name != $sidecarName)))
+          | .template.template.spec.workers.template.spec.volumes =
+            ((.template.template.spec.workers.template.spec.volumes // [])
+              | map(select(.name != $sshVolume.name and .name != "sybil-codex-workspace"))
+              + [$sshVolume])
+        else
+          .
+        end
+      )
+    ' <<<"$workload_json")"
+  patch="$(jq -n --argjson pools "$pools" '{spec: {pools: $pools}}')"
+  kubectl --context "$CLUSTER" -n "$NAMESPACE" patch workload "$WORKLOAD" --type=merge -p "$patch"
+}
+
+patch_workload_codex_mount
+patch_pool_codex_mount
+
+echo "Waiting for $WORKLOAD-0 to run the current pool revision..."
+deadline=$((SECONDS + 300))
+while true; do
+  pool_revision="$(kubectl --context "$CLUSTER" -n "$NAMESPACE" get pool "$WORKLOAD" -o jsonpath='{.status.revision}' 2>/dev/null || true)"
+  pod_revision="$(kubectl --context "$CLUSTER" -n "$NAMESPACE" get pod "$WORKLOAD-0" -o jsonpath='{.metadata.labels.brix\.openai\.com/revision}' 2>/dev/null || true)"
+  pod_ready="$(kubectl --context "$CLUSTER" -n "$NAMESPACE" get pod "$WORKLOAD-0" -o jsonpath='{.status.conditions[?(@.type=="Ready")].status}' 2>/dev/null || true)"
+  pod_deletion_timestamp="$(kubectl --context "$CLUSTER" -n "$NAMESPACE" get pod "$WORKLOAD-0" -o jsonpath='{.metadata.deletionTimestamp}' 2>/dev/null || true)"
+
+  if [[ -n "$pool_revision" && "$pod_revision" == "$pool_revision" && "$pod_ready" == "True" && -z "$pod_deletion_timestamp" ]]; then
+    break
+  fi
+
+  if (( SECONDS >= deadline )); then
+    echo "Timed out waiting for current ready pod. pool_revision=$pool_revision pod_revision=$pod_revision pod_ready=$pod_ready deleting=$pod_deletion_timestamp" >&2
+    exit 1
+  fi
+
+  sleep 5
+done
+
+brix run --clusters "$CLUSTER" --namespace "$NAMESPACE" --pools "$WORKLOAD" --dir "$REMOTE_ROOT" -- ./scripts/devbox-start.sh
+
+ssh_check="ssh -n -i '$CODEX_SSH_KEY_PATH' -o BatchMode=yes -o StrictHostKeyChecking=accept-new -o UserKnownHostsFile=/tmp/sybil-codex-known-hosts -p '$CODEX_SSH_PORT' root@'$CODEX_SERVICE' true"
+brix run --clusters "$CLUSTER" --namespace "$NAMESPACE" --pools "$WORKLOAD" --dir "$REMOTE_ROOT" -- /bin/bash -lc "$ssh_check"
+
+url="$(brix ingress create --cluster "$CLUSTER" --namespace "$NAMESPACE" --pod "$WORKLOAD-0" --ports "web:$INGRESS_PORT" --root web --timeout 300 "$WORKLOAD" | tail -1)"
+
+echo "Devbox update complete: $url"

server/prisma/migrations/20260816000000_add_chat_forks/migration.sql

@@ -0,0 +1,5 @@
+-- Add durable root grouping and one-time fork title generation state.
+ALTER TABLE "Chat" ADD COLUMN "parentChatId" TEXT REFERENCES "Chat"("id") ON DELETE CASCADE ON UPDATE CASCADE;
+ALTER TABLE "Chat" ADD COLUMN "titleGenerationPending" BOOLEAN NOT NULL DEFAULT false;
+
+CREATE INDEX "Chat_parentChatId_idx" ON "Chat"("parentChatId");

server/prisma/schema.prisma

@@ -51,7 +51,8 @@ model Chat {
   createdAt DateTime @default(now())
   updatedAt DateTime @updatedAt
 
-  title String?
+  title                  String?
+  titleGenerationPending Boolean @default(false)
 
   initiatedProvider Provider?
   initiatedModel    String?
@@ -64,11 +65,17 @@ model Chat {
   user   User?   @relation(fields: [userId], references: [id])
   userId String?
 
+  // Forks always point directly to the single root chat, never to another fork.
+  parentChat   Chat?  @relation("ChatForks", fields: [parentChatId], references: [id], onDelete: Cascade)
+  parentChatId String?
+  childChats   Chat[] @relation("ChatForks")
+
   messages Message[]
   calls    LlmCall[]
   projectItems ProjectItem[]
 
   @@index([userId])
+  @@index([parentChatId])
 }
 
 model Message {

server/src/routes.ts

@@ -1,3 +1,4 @@
+import { randomUUID } from "node:crypto";
 import { performance } from "node:perf_hooks";
 import { z } from "zod";
 import type { FastifyInstance, FastifyReply, FastifyRequest } from "fastify";
@@ -18,6 +19,7 @@ import type { ChatAttachment } from "./llm/types.js";
 
 const ProviderSchema = z.enum(["openai", "anthropic", "xai", "gemini", "hermes-agent"]);
 const MAX_ADDITIONAL_SYSTEM_PROMPT_CHARS = 12_000;
+const MAX_FORK_MESSAGE_SNIPPET_CHARS = 48;
 const EnabledToolsSchema = z.array(z.string().trim().min(1).max(80)).max(20).transform((value) => normalizeEnabledChatTools(value));
 
 type IncomingChatMessage = {
@@ -94,7 +96,7 @@ async function storeNonAssistantMessages(chatId: string, messages: IncomingChatM
 
   const existing = await prisma.message.findMany({
     where: { chatId },
-    orderBy: { createdAt: "asc" },
+    orderBy: [{ createdAt: "asc" }, { id: "asc" }],
     select: { role: true, content: true, name: true, metadata: true },
   });
   const existingNonAssistant = existing.filter((m) => m.role !== "assistant" && !isToolCallLogMessage(m));
@@ -317,6 +319,21 @@ function normalizeSuggestedTitle(raw: string, fallback: string) {
   return words.slice(0, 4).join(" ").slice(0, 64).trim() || fallback;
 }
 
+export function buildForkTitle(originalTitle: string | null, messageContent?: string) {
+  if (messageContent !== undefined) {
+    const snippet = truncateContextPart(messageContent.replace(/\s+/g, " "), MAX_FORK_MESSAGE_SNIPPET_CHARS) ?? "message";
+    return `Fork of '${snippet}'`;
+  }
+  return `Fork of ${originalTitle?.trim() || "Untitled chat"}`;
+}
+
+export function copyForkMessageMetadata(metadata: unknown) {
+  if (metadata === null || metadata === undefined) return undefined;
+  if (typeof metadata !== "object" || Array.isArray(metadata)) return metadata;
+  const { clientRequestId: _clientRequestId, ...copied } = metadata as Record<string, unknown>;
+  return Object.keys(copied).length ? copied : undefined;
+}
+
 async function generateChatTitle(content: string) {
   const systemPrompt =
     "You create short chat titles. Return exactly one line, maximum 4 words, no quotes, no trailing punctuation.";
@@ -415,6 +432,7 @@ type SearchRunRequest = z.infer<typeof SearchRunBody>;
 
 const activeChatStreams = new Map<string, ActiveSseStream>();
 const activeChatStreamRequestIds = new Map<string, string>();
+const chatDeletionRoots = new Set<string>();
 const activeSearchStreams = new Map<string, ActiveSseStream>();
 const STARRED_PROJECT_ID = "starred";
 
@@ -427,6 +445,8 @@ const starredProjectItemsSelect = {
 const chatSummarySelect = {
   id: true,
   title: true,
+  titleGenerationPending: true,
+  parentChatId: true,
   createdAt: true,
   updatedAt: true,
   initiatedProvider: true,
@@ -507,6 +527,29 @@ async function getSearchSummary(searchId: string) {
   return search ? serializeSearchLike(search) : null;
 }
 
+async function listRecentChatsWithRoots() {
+  const chats = await prisma.chat.findMany({
+    orderBy: { updatedAt: "desc" },
+    take: 100,
+    select: chatSummarySelect,
+  });
+  const includedIds = new Set(chats.map((chat) => chat.id));
+  const missingRootIds = [
+    ...new Set(
+      chats
+        .map((chat) => chat.parentChatId)
+        .filter((id): id is string => id !== null && !includedIds.has(id))
+    ),
+  ];
+  if (!missingRootIds.length) return chats;
+
+  const roots = await prisma.chat.findMany({
+    where: { id: { in: missingRootIds } },
+    select: chatSummarySelect,
+  });
+  return [...chats, ...roots].sort(compareUpdatedAtDesc);
+}
+
 async function setChatStarred(chatId: string, starred: boolean) {
   const exists = await prisma.chat.findUnique({ where: { id: chatId }, select: { id: true } });
   if (!exists) return null;
@@ -545,11 +588,7 @@ async function setSearchStarred(searchId: string, starred: boolean) {
 
 async function listWorkspaceItems() {
   const [chats, searches] = await Promise.all([
-    prisma.chat.findMany({
-      orderBy: { updatedAt: "desc" },
-      take: 100,
-      select: chatSummarySelect,
-    }),
+    listRecentChatsWithRoots(),
     prisma.search.findMany({
       orderBy: { updatedAt: "desc" },
       take: 100,
@@ -605,7 +644,7 @@ function mapChatStreamEvent(ev: StreamEvent): SseStreamEvent {
   return { event: ev.type, data: ev };
 }
 
-function registerActiveChatStream(chatId: string, clientRequestId?: string) {
+export function registerActiveChatStream(chatId: string, clientRequestId?: string) {
   const stream = new ActiveSseStream();
   activeChatStreams.set(chatId, stream);
   if (clientRequestId) {
@@ -616,7 +655,7 @@ function registerActiveChatStream(chatId: string, clientRequestId?: string) {
   return stream;
 }
 
-function clearActiveChatStream(chatId: string, stream: ActiveSseStream) {
+export function clearActiveChatStream(chatId: string, stream: ActiveSseStream) {
   if (activeChatStreams.get(chatId) !== stream) return;
   activeChatStreams.delete(chatId);
   activeChatStreamRequestIds.delete(chatId);
@@ -647,12 +686,6 @@ function executeActiveChatStream(chatId: string, body: z.infer<typeof Completion
   })();
 }
 
-function startActiveChatStream(chatId: string, body: z.infer<typeof CompletionStreamBody>) {
-  const stream = registerActiveChatStream(chatId, body.clientRequestId);
-  executeActiveChatStream(chatId, body, stream);
-  return stream;
-}
-
 function getMetadataClientRequestId(metadata: unknown) {
   if (!metadata || typeof metadata !== "object" || Array.isArray(metadata)) return null;
   const clientRequestId = (metadata as Record<string, unknown>).clientRequestId;
@@ -888,11 +921,7 @@ export async function registerRoutes(app: FastifyInstance) {
 
   app.get("/v1/chats", async (req) => {
     requireAdmin(req);
-    const chats = await prisma.chat.findMany({
-      orderBy: { updatedAt: "desc" },
-      take: 100,
-      select: chatSummarySelect,
-    });
+    const chats = await listRecentChatsWithRoots();
     return { chats: chats.map((chat) => serializeChatLike(chat)) };
   });
 
@@ -951,6 +980,80 @@ export async function registerRoutes(app: FastifyInstance) {
     return { chat: serializeChatLike(chat) };
   });
 
+  app.post("/v1/chats/:chatId/fork", async (req) => {
+    requireAdmin(req);
+    const Params = z.object({ chatId: z.string() });
+    const Body = z.object({ messageId: z.string().trim().min(1).optional() });
+    const { chatId } = Params.parse(req.params);
+    const parsed = Body.safeParse(req.body ?? {});
+    if (!parsed.success) return app.httpErrors.badRequest(parsed.error.message);
+
+    const result = await prisma.$transaction(async (tx) => {
+      const source = await tx.chat.findUnique({
+        where: { id: chatId },
+        select: {
+          id: true,
+          title: true,
+          parentChatId: true,
+          initiatedProvider: true,
+          initiatedModel: true,
+          lastUsedProvider: true,
+          lastUsedModel: true,
+          additionalSystemPrompt: true,
+          enabledTools: true,
+          userId: true,
+          messages: { orderBy: [{ createdAt: "asc" }, { id: "asc" }] },
+        },
+      });
+      if (!source) return { status: "chat-not-found" as const };
+
+      let messages = source.messages;
+      let selectedMessage: (typeof source.messages)[number] | undefined;
+      if (parsed.data.messageId) {
+        const selectedIndex = messages.findIndex((message) => message.id === parsed.data.messageId);
+        if (selectedIndex < 0) return { status: "message-not-found" as const };
+        selectedMessage = messages[selectedIndex];
+        if (selectedMessage.role !== "assistant") return { status: "message-not-assistant" as const };
+        messages = messages.slice(0, selectedIndex + 1);
+      }
+
+      const forkMessageIdPrefix = `fork-${randomUUID()}`;
+      const chat = await tx.chat.create({
+        data: {
+          title: buildForkTitle(source.title, selectedMessage?.content),
+          titleGenerationPending: true,
+          parentChatId: source.parentChatId ?? source.id,
+          initiatedProvider: source.initiatedProvider,
+          initiatedModel: source.initiatedModel,
+          lastUsedProvider: source.lastUsedProvider,
+          lastUsedModel: source.lastUsedModel,
+          additionalSystemPrompt: source.additionalSystemPrompt,
+          enabledTools: (source.enabledTools ?? undefined) as any,
+          userId: source.userId,
+          messages: messages.length
+            ? {
+                create: messages.map((message, index) => ({
+                  id: `${forkMessageIdPrefix}-${String(index).padStart(8, "0")}`,
+                  createdAt: message.createdAt,
+                  role: message.role,
+                  content: message.content,
+                  name: message.name,
+                  metadata: copyForkMessageMetadata(message.metadata) as any,
+                })),
+              }
+            : undefined,
+        },
+        select: chatSummarySelect,
+      });
+      return { status: "created" as const, chat };
+    });
+
+    if (result.status === "chat-not-found") return app.httpErrors.notFound("chat not found");
+    if (result.status === "message-not-found") return app.httpErrors.notFound("message not found in chat");
+    if (result.status === "message-not-assistant") return app.httpErrors.badRequest("fork message must be an assistant response");
+    return { chat: serializeChatLike(result.chat) };
+  });
+
   app.patch("/v1/chats/:chatId", async (req) => {
     requireAdmin(req);
     const Params = z.object({ chatId: z.string() });
@@ -963,7 +1066,10 @@ export async function registerRoutes(app: FastifyInstance) {
     const body = Body.parse(req.body ?? {});
 
     const data: Record<string, unknown> = {};
-    if (body.title !== undefined) data.title = body.title;
+    if (body.title !== undefined) {
+      data.title = body.title;
+      data.titleGenerationPending = false;
+    }
     if (body.additionalSystemPrompt !== undefined) data.additionalSystemPrompt = normalizeAdditionalSystemPrompt(body.additionalSystemPrompt);
     if (body.enabledTools !== undefined) data.enabledTools = body.enabledTools;
 
@@ -1004,7 +1110,7 @@ export async function registerRoutes(app: FastifyInstance) {
       select: chatSummarySelect,
     });
     if (!existing) return app.httpErrors.notFound("chat not found");
-    if (existing.title?.trim()) return { chat: serializeChatLike(existing) };
+    if (existing.title?.trim() && !existing.titleGenerationPending) return { chat: serializeChatLike(existing) };
 
     const fallback = body.content.split(/\r?\n/)[0]?.trim().slice(0, 48) || "New chat";
     let suggestedRaw = "";
@@ -1022,8 +1128,12 @@ export async function registerRoutes(app: FastifyInstance) {
     const title = normalizeSuggestedTitle(suggestedRaw, fallback);
 
     await prisma.chat.updateMany({
-      where: { id: body.chatId, title: existing.title },
-      data: { title },
+      where: {
+        id: body.chatId,
+        title: existing.title,
+        titleGenerationPending: existing.titleGenerationPending,
+      },
+      data: { title, titleGenerationPending: false },
     });
 
     const chat = await getChatSummary(body.chatId);
@@ -1039,14 +1149,46 @@ export async function registerRoutes(app: FastifyInstance) {
 
     req.log.info({ chatId }, "delete chat requested");
 
-    const result = await prisma.chat.deleteMany({ where: { id: chatId } });
-    if (result.count === 0) {
+    const target = await prisma.chat.findUnique({
+      where: { id: chatId },
+      select: { parentChatId: true },
+    });
+    if (!target) {
       req.log.warn({ chatId }, "delete chat target not found");
       return app.httpErrors.notFound("chat not found");
     }
 
-    req.log.info({ chatId }, "chat deleted");
-    return { deleted: true };
+    const familyRootId = target.parentChatId ?? chatId;
+    if (chatDeletionRoots.has(familyRootId)) {
+      return app.httpErrors.conflict("chat family deletion already in progress");
+    }
+
+    chatDeletionRoots.add(familyRootId);
+    try {
+      const familyIds = target.parentChatId
+        ? [chatId]
+        : (
+            await prisma.chat.findMany({
+              where: { OR: [{ id: chatId }, { parentChatId: chatId }] },
+              select: { id: true },
+            })
+          ).map((chat) => chat.id);
+      if (familyIds.some((id) => activeChatStreams.has(id))) {
+        req.log.warn({ chatId }, "delete chat rejected while chat family is active");
+        return app.httpErrors.conflict("chat or fork has an active stream");
+      }
+
+      const result = await prisma.chat.deleteMany({ where: { id: chatId } });
+      if (result.count === 0) {
+        req.log.warn({ chatId }, "delete chat target no longer exists");
+        return app.httpErrors.notFound("chat not found");
+      }
+
+      req.log.info({ chatId }, "chat deleted");
+      return { deleted: true };
+    } finally {
+      chatDeletionRoots.delete(familyRootId);
+    }
   });
 
   app.get("/v1/searches", async (req) => {
@@ -1336,7 +1478,7 @@ export async function registerRoutes(app: FastifyInstance) {
     const chat = await prisma.chat.findUnique({
       where: { id: chatId },
       include: {
-        messages: { orderBy: { createdAt: "asc" } },
+        messages: { orderBy: [{ createdAt: "asc" }, { id: "asc" }] },
         calls: { orderBy: { createdAt: "desc" } },
         projectItems: starredProjectItemsSelect,
       },
@@ -1430,10 +1572,15 @@ export async function registerRoutes(app: FastifyInstance) {
     if (!parsed.success) return app.httpErrors.badRequest(parsed.error.message);
     const body = withRequestUserLocation(parsed.data, req);
 
-    // ensure chat exists if provided
+    // Ensure the chat exists and identify its family before reserving a stream.
+    let chatFamilyRootId: string | null = null;
     if (body.chatId) {
-      const exists = await prisma.chat.findUnique({ where: { id: body.chatId }, select: { id: true } });
+      const exists = await prisma.chat.findUnique({
+        where: { id: body.chatId },
+        select: { id: true, parentChatId: true },
+      });
       if (!exists) return app.httpErrors.notFound("chat not found");
+      chatFamilyRootId = exists.parentChatId ?? exists.id;
     }
 
     if (body.persist !== false && body.chatId) {
@@ -1445,32 +1592,31 @@ export async function registerRoutes(app: FastifyInstance) {
         return app.httpErrors.conflict("chat completion already running");
       }
 
-      if (body.clientRequestId) {
-        const reservedStream = registerActiveChatStream(body.chatId, body.clientRequestId);
-        try {
+      if (chatFamilyRootId && chatDeletionRoots.has(chatFamilyRootId)) {
+        return app.httpErrors.conflict("chat family deletion already in progress");
+      }
+
+      const reservedStream = registerActiveChatStream(body.chatId, body.clientRequestId);
+      try {
+        if (body.clientRequestId) {
           const completedSubmission = await findCompletedChatSubmission(body.chatId, body.clientRequestId);
           if (completedSubmission) {
             completeChatSubmissionStream(reservedStream, body.chatId, body, completedSubmission.content);
             clearActiveChatStream(body.chatId, reservedStream);
             return streamActiveRun(req, reply, reservedStream);
           }
-
-          // Store only new non-assistant messages to avoid duplicate history entries.
-          await storeNonAssistantMessages(body.chatId, body.messages, body.clientRequestId);
-          const configuredBody = await applyStoredChatSettings(body);
-          executeActiveChatStream(body.chatId, configuredBody, reservedStream);
-          return streamActiveRun(req, reply, reservedStream);
-        } catch (err) {
-          reservedStream.complete({ event: "error", data: { message: getErrorMessage(err) } });
-          clearActiveChatStream(body.chatId, reservedStream);
-          throw err;
         }
-      }
 
-      // Legacy requests without an idempotency key retain the original behavior.
-      await storeNonAssistantMessages(body.chatId, body.messages);
-      const stream = startActiveChatStream(body.chatId, await applyStoredChatSettings(body));
-      return streamActiveRun(req, reply, stream);
+        // Reserve the stream before persistence so deletion cannot interleave with setup.
+        await storeNonAssistantMessages(body.chatId, body.messages, body.clientRequestId);
+        const configuredBody = await applyStoredChatSettings(body);
+        executeActiveChatStream(body.chatId, configuredBody, reservedStream);
+        return streamActiveRun(req, reply, reservedStream);
+      } catch (err) {
+        reservedStream.complete({ event: "error", data: { message: getErrorMessage(err) } });
+        clearActiveChatStream(body.chatId, reservedStream);
+        throw err;
+      }
     }
 
     reply.raw.writeHead(200, buildSseHeaders(typeof req.headers.origin === "string" ? req.headers.origin : undefined));

server/tests/chat-forks.test.ts

@@ -0,0 +1,252 @@
+import assert from "node:assert/strict";
+import { execFileSync } from "node:child_process";
+import { mkdtempSync, rmSync } from "node:fs";
+import { tmpdir } from "node:os";
+import { dirname, join, resolve } from "node:path";
+import test from "node:test";
+import { fileURLToPath } from "node:url";
+import Fastify from "fastify";
+import sensible from "@fastify/sensible";
+
+const serverRoot = resolve(dirname(fileURLToPath(import.meta.url)), "..");
+const databaseDir = mkdtempSync(join(tmpdir(), "sybil-chat-forks-"));
+process.env.DATABASE_URL = `file:${join(databaseDir, "test.db")}`;
+process.env.OPENAI_API_KEY = "";
+delete process.env.ADMIN_TOKEN;
+
+execFileSync(process.execPath, [join(serverRoot, "node_modules/prisma/build/index.js"), "migrate", "deploy"], {
+  cwd: serverRoot,
+  env: { ...process.env, PRISMA_HIDE_UPDATE_MESSAGE: "1" },
+  stdio: "pipe",
+});
+
+const [{ clearActiveChatStream, registerActiveChatStream, registerRoutes }, { prisma }] = await Promise.all([
+  import("../src/routes.js"),
+  import("../src/db.js"),
+]);
+const app = Fastify({ logger: false });
+await app.register(sensible);
+await registerRoutes(app);
+await app.ready();
+
+test.after(async () => {
+  await app.close();
+  await prisma.$disconnect();
+  rmSync(databaseDir, { recursive: true, force: true });
+});
+
+test("forks copy bounded history and keep every child grouped under the root", async () => {
+  const timestamp = new Date("2026-08-16T12:00:00.000Z");
+  const source = await prisma.chat.create({
+    data: {
+      title: "Planning session",
+      initiatedProvider: "openai",
+      initiatedModel: "gpt-4.1-mini",
+      lastUsedProvider: "anthropic",
+      lastUsedModel: "claude-sonnet-4-20250514",
+      additionalSystemPrompt: "Keep answers concise.",
+      enabledTools: ["web_search"],
+      messages: {
+        create: [
+          {
+            id: "source-message-0001",
+            createdAt: timestamp,
+            role: "user",
+            content: "Plan a trip",
+            metadata: {
+              clientRequestId: "source-request",
+              attachments: [{ kind: "text", filename: "notes.txt" }],
+            },
+          },
+          {
+            id: "source-message-0002",
+            createdAt: timestamp,
+            role: "assistant",
+            content: "First assistant response",
+            metadata: { clientRequestId: "source-request", citations: ["https://example.com"] },
+          },
+          {
+            id: "source-message-0003",
+            createdAt: timestamp,
+            role: "user",
+            content: "Only visible in a whole-chat fork",
+          },
+        ],
+      },
+      calls: {
+        create: {
+          provider: "openai",
+          model: "gpt-4.1-mini",
+          request: { input: "Plan a trip" },
+        },
+      },
+    },
+    include: { messages: { orderBy: [{ createdAt: "asc" }, { id: "asc" }] } },
+  });
+
+  const forkResponse = await app.inject({
+    method: "POST",
+    url: `/v1/chats/${source.id}/fork`,
+    payload: { messageId: source.messages[1].id },
+  });
+  assert.equal(forkResponse.statusCode, 200, forkResponse.body);
+  const forkSummary = forkResponse.json().chat;
+  assert.equal(forkSummary.parentChatId, source.id);
+  assert.equal(forkSummary.title, "Fork of 'First assistant response'");
+  assert.equal(forkSummary.titleGenerationPending, true);
+  assert.equal(forkSummary.starred, false);
+
+  const detailResponse = await app.inject({ method: "GET", url: `/v1/chats/${forkSummary.id}` });
+  assert.equal(detailResponse.statusCode, 200, detailResponse.body);
+  const fork = detailResponse.json().chat;
+  assert.deepEqual(
+    fork.messages.map((message: any) => [message.role, message.content]),
+    [
+      ["user", "Plan a trip"],
+      ["assistant", "First assistant response"],
+    ]
+  );
+  assert.notEqual(fork.messages[0].id, source.messages[0].id);
+  assert.equal(fork.messages[0].createdAt, timestamp.toISOString());
+  assert.deepEqual(fork.messages[0].metadata, {
+    attachments: [{ kind: "text", filename: "notes.txt" }],
+  });
+  assert.deepEqual(fork.messages[1].metadata, { citations: ["https://example.com"] });
+  assert.equal(fork.initiatedProvider, "openai");
+  assert.equal(fork.initiatedModel, "gpt-4.1-mini");
+  assert.equal(fork.lastUsedProvider, "anthropic");
+  assert.equal(fork.lastUsedModel, "claude-sonnet-4-20250514");
+  assert.equal(fork.additionalSystemPrompt, "Keep answers concise.");
+  assert.deepEqual(fork.enabledTools, ["web_search"]);
+  assert.deepEqual(fork.calls, []);
+
+  const childForkResponse = await app.inject({
+    method: "POST",
+    url: `/v1/chats/${forkSummary.id}/fork`,
+    payload: {},
+  });
+  assert.equal(childForkResponse.statusCode, 200, childForkResponse.body);
+  const childFork = childForkResponse.json().chat;
+  assert.equal(childFork.parentChatId, source.id);
+  assert.equal(childFork.title, "Fork of Fork of 'First assistant response'");
+  assert.equal(childFork.titleGenerationPending, true);
+
+  const wholeForkResponse = await app.inject({
+    method: "POST",
+    url: `/v1/chats/${source.id}/fork`,
+    payload: {},
+  });
+  assert.equal(wholeForkResponse.statusCode, 200, wholeForkResponse.body);
+  const wholeFork = wholeForkResponse.json().chat;
+  assert.equal(wholeFork.parentChatId, source.id);
+  assert.equal(wholeFork.title, "Fork of Planning session");
+  const wholeForkDetail = await app.inject({ method: "GET", url: `/v1/chats/${wholeFork.id}` });
+  assert.equal(wholeForkDetail.statusCode, 200, wholeForkDetail.body);
+  assert.deepEqual(
+    wholeForkDetail.json().chat.messages.map((message: any) => message.content),
+    ["Plan a trip", "First assistant response", "Only visible in a whole-chat fork"]
+  );
+  assert.equal(wholeForkDetail.json().chat.messages[2].metadata, null);
+
+  const suggestedTitleResponse = await app.inject({
+    method: "POST",
+    url: "/v1/chats/title/suggest",
+    payload: { chatId: wholeFork.id, content: "Compare rail and air options" },
+  });
+  assert.equal(suggestedTitleResponse.statusCode, 200, suggestedTitleResponse.body);
+  assert.equal(suggestedTitleResponse.json().chat.title, "Compare rail and air");
+  assert.equal(suggestedTitleResponse.json().chat.titleGenerationPending, false);
+
+  const repeatedTitleResponse = await app.inject({
+    method: "POST",
+    url: "/v1/chats/title/suggest",
+    payload: { chatId: wholeFork.id, content: "This must not overwrite the generated title" },
+  });
+  assert.equal(repeatedTitleResponse.statusCode, 200, repeatedTitleResponse.body);
+  assert.equal(repeatedTitleResponse.json().chat.title, "Compare rail and air");
+
+  const sourceAfterForks = await prisma.chat.findUniqueOrThrow({
+    where: { id: source.id },
+    include: { messages: true, calls: true },
+  });
+  assert.equal(sourceAfterForks.messages.length, 3);
+  assert.equal(sourceAfterForks.calls.length, 1);
+
+  const manualTitleResponse = await app.inject({
+    method: "PATCH",
+    url: `/v1/chats/${forkSummary.id}`,
+    payload: { title: "Manual branch title" },
+  });
+  assert.equal(manualTitleResponse.statusCode, 200, manualTitleResponse.body);
+  assert.equal(manualTitleResponse.json().chat.titleGenerationPending, false);
+
+  const activeForkStream = registerActiveChatStream(wholeFork.id);
+  try {
+    const deleteActiveRootResponse = await app.inject({ method: "DELETE", url: `/v1/chats/${source.id}` });
+    assert.equal(deleteActiveRootResponse.statusCode, 409, deleteActiveRootResponse.body);
+    assert.equal(deleteActiveRootResponse.json().message, "chat or fork has an active stream");
+
+    const deleteActiveForkResponse = await app.inject({ method: "DELETE", url: `/v1/chats/${wholeFork.id}` });
+    assert.equal(deleteActiveForkResponse.statusCode, 409, deleteActiveForkResponse.body);
+  } finally {
+    clearActiveChatStream(wholeFork.id, activeForkStream);
+  }
+
+  const deleteChildResponse = await app.inject({ method: "DELETE", url: `/v1/chats/${childFork.id}` });
+  assert.equal(deleteChildResponse.statusCode, 200, deleteChildResponse.body);
+  assert.equal(await prisma.chat.count({ where: { id: { in: [source.id, forkSummary.id, wholeFork.id] } } }), 3);
+
+  const unrelated = await prisma.chat.create({
+    data: {
+      messages: { create: { role: "assistant", content: "Unrelated response" } },
+    },
+    include: { messages: true },
+  });
+  const countBeforeInvalidForks = await prisma.chat.count();
+
+  const wrongChatResponse = await app.inject({
+    method: "POST",
+    url: `/v1/chats/${source.id}/fork`,
+    payload: { messageId: unrelated.messages[0].id },
+  });
+  assert.equal(wrongChatResponse.statusCode, 404, wrongChatResponse.body);
+  assert.equal(wrongChatResponse.json().message, "message not found in chat");
+
+  const nonAssistantResponse = await app.inject({
+    method: "POST",
+    url: `/v1/chats/${source.id}/fork`,
+    payload: { messageId: source.messages[0].id },
+  });
+  assert.equal(nonAssistantResponse.statusCode, 400, nonAssistantResponse.body);
+  assert.equal(nonAssistantResponse.json().message, "fork message must be an assistant response");
+  assert.equal(await prisma.chat.count(), countBeforeInvalidForks);
+
+  const concurrentTarget = await prisma.chat.create({ data: { title: "Concurrent delete" } });
+  const concurrentDeleteResponses = await Promise.all([
+    app.inject({ method: "DELETE", url: `/v1/chats/${concurrentTarget.id}` }),
+    app.inject({ method: "DELETE", url: `/v1/chats/${concurrentTarget.id}` }),
+  ]);
+  assert.equal(concurrentDeleteResponses.filter((response) => response.statusCode === 200).length, 1);
+  assert.equal(concurrentDeleteResponses.some((response) => response.statusCode >= 500), false);
+
+  const concurrentRoot = await prisma.chat.create({ data: { title: "Concurrent family delete" } });
+  const concurrentChildResponse = await app.inject({
+    method: "POST",
+    url: `/v1/chats/${concurrentRoot.id}/fork`,
+    payload: {},
+  });
+  assert.equal(concurrentChildResponse.statusCode, 200, concurrentChildResponse.body);
+  const concurrentChild = concurrentChildResponse.json().chat;
+  const concurrentFamilyDeleteResponses = await Promise.all([
+    app.inject({ method: "DELETE", url: `/v1/chats/${concurrentRoot.id}` }),
+    app.inject({ method: "DELETE", url: `/v1/chats/${concurrentChild.id}` }),
+  ]);
+  assert.equal(concurrentFamilyDeleteResponses.some((response) => response.statusCode >= 500), false);
+  assert.equal(concurrentFamilyDeleteResponses.some((response) => response.statusCode === 200), true);
+  await prisma.chat.deleteMany({ where: { id: concurrentRoot.id } });
+
+  const deleteRootResponse = await app.inject({ method: "DELETE", url: `/v1/chats/${source.id}` });
+  assert.equal(deleteRootResponse.statusCode, 200, deleteRootResponse.body);
+  assert.equal(await prisma.chat.count({ where: { id: { in: [source.id, forkSummary.id, childFork.id, wholeFork.id] } } }), 0);
+  assert.equal(await prisma.chat.count({ where: { id: unrelated.id } }), 1);
+});

tui/src/index.ts

@@ -127,21 +127,27 @@ function upsertWorkspaceItem(items: WorkspaceItem[], item: WorkspaceItem) {
 }
 
 function buildSidebarItems(items: WorkspaceItem[]): SidebarItem[] {
+  const chatsById = new Map<string, ChatSummary>();
+  for (const item of items) {
+    if (item.type === "chat") chatsById.set(item.id, item);
+  }
+
   return items.map((item) => {
     if (item.type === "chat") {
       const chat = item;
+      const starOwner = chatsById.get(chat.parentChatId ?? chat.id) ?? chat;
       return {
-      kind: "chat" as const,
-      id: chat.id,
-      title: getChatTitle(chat),
-      updatedAt: chat.updatedAt,
-      createdAt: chat.createdAt,
-      starred: chat.starred,
-      starredAt: chat.starredAt,
-      initiatedProvider: chat.initiatedProvider,
-      initiatedModel: chat.initiatedModel,
-      lastUsedProvider: chat.lastUsedProvider,
-      lastUsedModel: chat.lastUsedModel,
+        kind: "chat" as const,
+        id: chat.id,
+        title: getChatTitle(chat),
+        updatedAt: chat.updatedAt,
+        createdAt: chat.createdAt,
+        starred: starOwner.starred,
+        starredAt: starOwner.starredAt,
+        initiatedProvider: chat.initiatedProvider,
+        initiatedModel: chat.initiatedModel,
+        lastUsedProvider: chat.lastUsedProvider,
+        lastUsedModel: chat.lastUsedModel,
       };
     }
 
@@ -979,11 +985,11 @@ async function main() {
     focusComposer();
   }
 
-  async function maybeSuggestTitle(chatId: string, content: string) {
-    const chatSummary = chats.find((chat) => chat.id === chatId);
-    const hasExistingTitle = Boolean(selectedChat?.id === chatId ? selectedChat.title?.trim() : chatSummary?.title?.trim());
-    if (hasExistingTitle || pendingTitleGeneration.has(chatId)) return;
+  async function maybeSuggestTitle(chat: ChatDetail, content: string) {
+    const needsGeneratedTitle = chat.titleGenerationPending || !chat.title?.trim();
+    if (!needsGeneratedTitle || pendingTitleGeneration.has(chat.id)) return;
 
+    const chatId = chat.id;
     pendingTitleGeneration.add(chatId);
     try {
       const updated = await api.suggestChatTitle({ chatId, content });
@@ -993,6 +999,8 @@ async function main() {
         selectedChat = {
           ...selectedChat,
           title: updated.title,
+          parentChatId: updated.parentChatId,
+          titleGenerationPending: updated.titleGenerationPending,
           updatedAt: updated.updatedAt,
           starred: updated.starred,
           starredAt: updated.starredAt,
@@ -1049,6 +1057,8 @@ async function main() {
       selectedChat = {
         id: chat.id,
         title: chat.title,
+        parentChatId: chat.parentChatId,
+        titleGenerationPending: chat.titleGenerationPending,
         createdAt: chat.createdAt,
         updatedAt: chat.updatedAt,
         starred: chat.starred,
@@ -1068,13 +1078,13 @@ async function main() {
       throw new Error("Unable to initialize chat");
     }
 
-    void maybeSuggestTitle(chatId, content);
-
     let baseChat = selectedChat;
     if (!baseChat || baseChat.id !== chatId) {
       baseChat = await api.getChat(chatId);
     }
 
+    void maybeSuggestTitle(baseChat, content);
+
     const requestMessages: CompletionRequestMessage[] = [
       ...baseChat.messages
         .filter((message) => !isToolCallLogMessage(message))
@@ -1392,6 +1402,8 @@ async function main() {
       selectedChat = {
         ...selectedChat,
         title: updated.title,
+        parentChatId: updated.parentChatId,
+        titleGenerationPending: updated.titleGenerationPending,
         updatedAt: updated.updatedAt,
         initiatedProvider: updated.initiatedProvider,
         initiatedModel: updated.initiatedModel,
@@ -1405,12 +1417,16 @@ async function main() {
   async function handleToggleStarSelection() {
     if (!selectedItem) return;
 
-    const currentItem = getSidebarItems().find((item) => item.kind === selectedItem?.kind && item.id === selectedItem?.id);
-    const nextStarred = !currentItem?.starred;
     setError(null);
 
     if (selectedItem.kind === "chat") {
-      const updated = await api.updateChatStar(selectedItem.id, nextStarred);
+      const selectedSummary = chats.find((chat) => chat.id === selectedItem?.id);
+      const selectedParentChatId = selectedChat?.id === selectedItem.id
+        ? selectedChat.parentChatId
+        : selectedSummary?.parentChatId;
+      const rootChatId = selectedParentChatId ?? selectedItem.id;
+      const rootSummary = chats.find((chat) => chat.id === rootChatId);
+      const updated = await api.updateChatStar(rootChatId, !rootSummary?.starred);
       chats = chats.map((chat) => (chat.id === updated.id ? updated : chat));
       if (!chats.some((chat) => chat.id === updated.id)) chats = [updated, ...chats];
       workspaceItems = workspaceItems.map((item) => (item.type === "chat" && item.id === updated.id ? chatWorkspaceItem(updated) : item));
@@ -1421,6 +1437,8 @@ async function main() {
         selectedChat = {
           ...selectedChat,
           title: updated.title,
+          parentChatId: updated.parentChatId,
+          titleGenerationPending: updated.titleGenerationPending,
           updatedAt: updated.updatedAt,
           starred: updated.starred,
           starredAt: updated.starredAt,
@@ -1431,7 +1449,8 @@ async function main() {
         };
       }
     } else {
-      const updated = await api.updateSearchStar(selectedItem.id, nextStarred);
+      const currentItem = getSidebarItems().find((item) => item.kind === "search" && item.id === selectedItem?.id);
+      const updated = await api.updateSearchStar(selectedItem.id, !currentItem?.starred);
       searches = searches.map((search) => (search.id === updated.id ? updated : search));
       if (!searches.some((search) => search.id === updated.id)) searches = [updated, ...searches];
       workspaceItems = workspaceItems.map((item) => (item.type === "search" && item.id === updated.id ? searchWorkspaceItem(updated) : item));

tui/src/types.ts

@@ -13,6 +13,8 @@ export type ModelCatalogResponse = {
 export type ChatSummary = {
   id: string;
   title: string | null;
+  parentChatId: string | null;
+  titleGenerationPending: boolean;
   createdAt: string;
   updatedAt: string;
   starred: boolean;
@@ -68,6 +70,8 @@ export type ToolCallEvent = {
 export type ChatDetail = {
   id: string;
   title: string | null;
+  parentChatId: string | null;
+  titleGenerationPending: boolean;
   createdAt: string;
   updatedAt: string;
   starred: boolean;

web/src/App.tsx

@@ -3,6 +3,7 @@ import type { TargetedTouchEvent } from "preact";
 import {
   Check,
   ChevronDown,
+  GitFork,
   Globe2,
   LoaderCircle,
   Menu,
@@ -32,6 +33,7 @@ import {
   createSearch,
   deleteChat,
   deleteSearch,
+  forkChat,
   attachCompletionStream,
   attachSearchStream,
   getActiveRuns,
@@ -67,6 +69,12 @@ import {
   getChatModelSelection,
   getChatModelSelectionSyncKey,
 } from "@/lib/chat-model-selection";
+import {
+  filterSidebarItemsWithForkGroups,
+  getForkGroupPresentation,
+  groupForkedChatItems,
+  shouldRequestChatTitle,
+} from "@/lib/chat-forking";
 import {
   resolveSidebarSelectionAfterRefresh,
   type SidebarSelection,
@@ -76,6 +84,7 @@ import { cn } from "@/lib/utils";
 type DraftSelectionKind = "chat" | "search";
 type SidebarItem = SidebarSelection & {
   title: string;
+  parentChatId: string | null;
   updatedAt: string;
   createdAt: string;
   starred: boolean;
@@ -86,9 +95,16 @@ type SidebarItem = SidebarSelection & {
   lastUsedModel: string | null;
 };
 type ContextMenuState = {
+  kind: "sidebar";
   item: SidebarSelection;
   x: number;
   y: number;
+} | {
+  kind: "message";
+  chatId: string;
+  messageId: string;
+  x: number;
+  y: number;
 };
 type RenameChatDialogState = {
   chatId: string;
@@ -809,6 +825,7 @@ function buildSidebarItems(items: WorkspaceItem[]): SidebarItem[] {
         kind: "chat" as const,
         id: chat.id,
         title: getChatTitle(chat),
+        parentChatId: chat.parentChatId,
         updatedAt: chat.updatedAt,
         createdAt: chat.createdAt,
         starred: chat.starred,
@@ -825,6 +842,7 @@ function buildSidebarItems(items: WorkspaceItem[]): SidebarItem[] {
       kind: "search" as const,
       id: search.id,
       title: getSearchTitle(search),
+      parentChatId: null,
       updatedAt: search.updatedAt,
       createdAt: search.createdAt,
       starred: search.starred,
@@ -879,20 +897,33 @@ function getSidebarSectionLabel(value: string) {
   return "EARLIER";
 }
 
-function buildSidebarSections(items: SidebarItem[]) {
-  const starred = items
-    .filter((item) => item.starred)
+function buildSidebarSections(items: SidebarItem[], allItems = items) {
+  const groups = groupForkedChatItems(items).map((groupItems) => {
+    const presentation = getForkGroupPresentation(groupItems, allItems);
+    return {
+      items: groupItems,
+      updatedAt: presentation?.updatedAt ?? groupItems[0].updatedAt,
+      starred: presentation?.starred ?? false,
+      starredAt: presentation?.starredAt ?? null,
+    };
+  });
+  const starred = groups
+    .filter((group) => group.starred)
     .sort((a, b) => new Date(b.starredAt ?? b.updatedAt).getTime() - new Date(a.starredAt ?? a.updatedAt).getTime());
-  const unstarred = items.filter((item) => !item.starred);
+  const unstarred = groups
+    .filter((group) => !group.starred)
+    .sort((a, b) => new Date(b.updatedAt).getTime() - new Date(a.updatedAt).getTime());
 
-  const sections = starred.length ? [{ label: "STARRED", items: starred }] : [];
-  return unstarred.reduce<Array<{ label: string; items: SidebarItem[] }>>((sections, item) => {
-    const label = getSidebarSectionLabel(item.updatedAt);
+  const sections: Array<{ label: string; items: SidebarItem[] }> = starred.length
+    ? [{ label: "STARRED", items: starred.flatMap((group) => group.items) }]
+    : [];
+  return unstarred.reduce<Array<{ label: string; items: SidebarItem[] }>>((sections, group) => {
+    const label = getSidebarSectionLabel(group.updatedAt);
     const section = sections.find((candidate) => candidate.label === label);
     if (section) {
-      section.items.push(item);
+      section.items.push(...group.items);
     } else {
-      sections.push({ label, items: [item] });
+      sections.push({ label, items: [...group.items] });
     }
     return sections;
   }, sections);
@@ -922,6 +953,7 @@ export default function App() {
   const [isLoadingCollections, setIsLoadingCollections] = useState(false);
   const [isLoadingSelection, setIsLoadingSelection] = useState(false);
   const [isStartingSearchChat, setIsStartingSearchChat] = useState(false);
+  const [isForkingChat, setIsForkingChat] = useState(false);
   const [pendingChatStates, setPendingChatStates] = useState<Record<string, PendingChatState>>({});
   const [runningSearchStates, setRunningSearchStates] = useState<Record<string, SearchDetail>>({});
   const [activeRuns, setActiveRuns] = useState<ActiveRunsState>(EMPTY_ACTIVE_RUNS);
@@ -979,6 +1011,12 @@ export default function App() {
   const pendingAttachmentsRef = useRef<ChatAttachment[]>([]);
   const composerDraftRef = useRef("");
   const selectedItemRef = useRef<SidebarSelection | null>(null);
+  const draftKindRef = useRef<DraftSelectionKind | null>(null);
+  const collectionLoadRequestRef = useRef(0);
+  const activeCollectionLoadRef = useRef<{ requestId: number; options: RefreshCollectionsOptions } | null>(null);
+  const selectionLoadRequestRef = useRef(0);
+  const forkRequestSequenceRef = useRef(0);
+  const activeForkRequestRef = useRef<number | null>(null);
   const pendingTitleGenerationRef = useRef<Set<string>>(new Set());
   const chatStreamAbortRefs = useRef<Map<string, AbortController>>(new Map());
   const backgroundSuspendedChatStreamsRef = useRef<Set<string>>(new Set());
@@ -1063,17 +1101,32 @@ export default function App() {
   const sidebarItems = useMemo(() => buildSidebarItems(workspaceItems), [workspaceItems]);
   const filteredSidebarItems = useMemo(() => {
     const query = sidebarQuery.trim().toLowerCase();
-    if (!query) return sidebarItems;
-    return sidebarItems.filter((item) => {
+    if (!query) return groupForkedChatItems(sidebarItems).flat();
+    return filterSidebarItemsWithForkGroups(sidebarItems, (item) => {
       const providerLabel = getProviderLabel(item.lastUsedProvider || item.initiatedProvider).toLowerCase();
       return [item.title, item.initiatedModel, item.lastUsedModel, providerLabel]
         .filter(Boolean)
         .some((value) => String(value).toLowerCase().includes(query));
     });
   }, [sidebarItems, sidebarQuery]);
-  const sidebarSections = useMemo(() => buildSidebarSections(filteredSidebarItems), [filteredSidebarItems]);
+  const sidebarSections = useMemo(
+    () => buildSidebarSections(filteredSidebarItems, sidebarItems),
+    [filteredSidebarItems, sidebarItems]
+  );
+  const orderedSidebarItems = useMemo(() => sidebarSections.flatMap((section) => section.items), [sidebarSections]);
+
+  const cancelCollectionLoad = () => {
+    collectionLoadRequestRef.current += 1;
+    activeCollectionLoadRef.current = null;
+    setIsLoadingCollections(false);
+  };
 
   const resetWorkspaceState = () => {
+    cancelCollectionLoad();
+    selectionLoadRequestRef.current += 1;
+    forkRequestSequenceRef.current += 1;
+    activeForkRequestRef.current = null;
+    draftKindRef.current = null;
     setChats([]);
     setSearches([]);
     setWorkspaceItems([]);
@@ -1119,6 +1172,7 @@ export default function App() {
     setRenameChatDraft("");
     setRenameChatError(null);
     setIsRenamingChat(false);
+    setIsForkingChat(false);
     setError(null);
   };
 
@@ -1132,32 +1186,52 @@ export default function App() {
     reportTransientError = true,
     selectFallback = false,
   }: RefreshCollectionsOptions = {}) => {
+    const requestId = ++collectionLoadRequestRef.current;
+    activeCollectionLoadRef.current = {
+      requestId,
+      options: { initialSelection, reportTransientError, selectFallback },
+    };
     setIsLoadingCollections(true);
     try {
       const nextWorkspaceItems = await listWorkspaceItems();
+      if (requestId !== collectionLoadRequestRef.current) return;
       const { chats: nextChats, searches: nextSearches } = splitWorkspaceItems(nextWorkspaceItems);
       setWorkspaceItems(nextWorkspaceItems);
       setChats(nextChats);
       setSearches(nextSearches);
 
-      setSelectedItem((current) =>
-        resolveSidebarSelectionAfterRefresh(current, nextWorkspaceItems, {
+      setSelectedItem((current) => {
+        const nextSelection = resolveSidebarSelectionAfterRefresh(current, nextWorkspaceItems, {
           initialSelection,
           selectFallback,
-        })
-      );
+        });
+        selectedItemRef.current = nextSelection;
+        return nextSelection;
+      });
     } catch (err) {
       const message = err instanceof Error ? err.message : String(err);
       if (message.includes("bearer token")) {
         handleAuthFailure(message);
-      } else if (reportTransientError || !isRecoverableStreamDisconnect(err)) {
+      } else if (
+        requestId === collectionLoadRequestRef.current &&
+        (reportTransientError || !isRecoverableStreamDisconnect(err))
+      ) {
         setError(message);
       }
     } finally {
-      setIsLoadingCollections(false);
+      if (requestId === collectionLoadRequestRef.current) {
+        activeCollectionLoadRef.current = null;
+        setIsLoadingCollections(false);
+      }
     }
   };
 
+  const supersedeCollectionLoad = () => {
+    const replacementOptions = activeCollectionLoadRef.current?.options;
+    cancelCollectionLoad();
+    if (replacementOptions) void refreshCollections(replacementOptions);
+  };
+
   const refreshModels = async () => {
     try {
       const data = await listModels();
@@ -1200,38 +1274,44 @@ export default function App() {
   };
 
   const refreshChat = async (chatId: string) => {
+    const requestId = ++selectionLoadRequestRef.current;
     setIsLoadingSelection(true);
     try {
       const chat = await getChat(chatId);
+      const current = selectedItemRef.current;
+      if (requestId !== selectionLoadRequestRef.current || current?.kind !== "chat" || current.id !== chatId) return;
       setSelectedChat(chat);
       setSelectedSearch(null);
     } catch (err) {
       const message = err instanceof Error ? err.message : String(err);
       if (message.includes("bearer token")) {
         handleAuthFailure(message);
-      } else if (!isRecoverableStreamDisconnect(err)) {
+      } else if (requestId === selectionLoadRequestRef.current && !isRecoverableStreamDisconnect(err)) {
         setError(message);
       }
     } finally {
-      setIsLoadingSelection(false);
+      if (requestId === selectionLoadRequestRef.current) setIsLoadingSelection(false);
     }
   };
 
   const refreshSearch = async (searchId: string) => {
+    const requestId = ++selectionLoadRequestRef.current;
     setIsLoadingSelection(true);
     try {
       const search = await getSearch(searchId);
+      const current = selectedItemRef.current;
+      if (requestId !== selectionLoadRequestRef.current || current?.kind !== "search" || current.id !== searchId) return;
       setSelectedSearch(search);
       setSelectedChat(null);
     } catch (err) {
       const message = err instanceof Error ? err.message : String(err);
       if (message.includes("bearer token")) {
         handleAuthFailure(message);
-      } else if (!isRecoverableStreamDisconnect(err)) {
+      } else if (requestId === selectionLoadRequestRef.current && !isRecoverableStreamDisconnect(err)) {
         setError(message);
       }
     } finally {
-      setIsLoadingSelection(false);
+      if (requestId === selectionLoadRequestRef.current) setIsLoadingSelection(false);
     }
   };
 
@@ -1296,8 +1376,11 @@ export default function App() {
   useEffect(() => {
     const onPopState = () => {
       setContextMenu(null);
+      draftKindRef.current = null;
       setDraftKind(null);
-      setSelectedItem(readSidebarSelectionFromUrl());
+      const target = readSidebarSelectionFromUrl();
+      selectedItemRef.current = target;
+      setSelectedItem(target);
       setIsMobileSidebarOpen(false);
     };
     window.addEventListener("popstate", onPopState);
@@ -1410,6 +1493,29 @@ export default function App() {
 
   const isItemRunning = (item: SidebarSelection) =>
     item.kind === "chat" ? !!pendingChatStates[item.id] || !!activeRuns.chats[item.id] : !!runningSearchStates[item.id] || !!activeRuns.searches[item.id];
+  const getChatFamilyItems = (chatId: string) => {
+    const chat = sidebarItems.find((item) => item.kind === "chat" && item.id === chatId);
+    if (!chat) return [];
+    const rootId = chat.parentChatId ?? chat.id;
+    return sidebarItems.filter(
+      (item) => item.kind === "chat" && (item.id === rootId || item.parentChatId === rootId)
+    );
+  };
+  const isRootChat = (item: SidebarSelection) => {
+    if (item.kind !== "chat") return false;
+    const chat = sidebarItems.find((candidate) => candidate.kind === "chat" && candidate.id === item.id);
+    return chat?.parentChatId === null;
+  };
+  const isDeleteBlocked = (item: SidebarSelection) => {
+    if (!isRootChat(item)) return isItemRunning(item);
+    return getChatFamilyItems(item.id).some((familyItem) => isItemRunning(familyItem));
+  };
+  const isSidebarTargetStarred = (item: SidebarSelection) => {
+    if (item.kind === "chat") {
+      return getChatFamilyItems(item.id).find((familyItem) => familyItem.parentChatId === null)?.starred ?? false;
+    }
+    return sidebarItems.find((candidate) => candidate.kind === "search" && candidate.id === item.id)?.starred ?? false;
+  };
   const isCurrentSelection = (item: SidebarSelection) => {
     const current = selectedItemRef.current;
     return current?.kind === item.kind && current.id === item.id;
@@ -1428,6 +1534,10 @@ export default function App() {
     selectedItemRef.current = selectedItem;
   }, [selectedItem]);
 
+  useEffect(() => {
+    draftKindRef.current = draftKind;
+  }, [draftKind]);
+
   useEffect(() => {
     if (!isAuthenticated) {
       setSelectedChat(null);
@@ -1597,7 +1707,7 @@ export default function App() {
     if (draftKind === "search") return "New search";
     if (!selectedItem) return "Sybil";
     if (selectedItem.kind === "chat") {
-      if (selectedChat) return getChatTitle(selectedChat, selectedChat.messages);
+      if (selectedChat?.id === selectedItem.id) return getChatTitle(selectedChat, selectedChat.messages);
       if (selectedChatSummary) return getChatTitle(selectedChatSummary);
       return "New chat";
     }
@@ -1609,7 +1719,7 @@ export default function App() {
   const pageTitle = useMemo(() => {
     if (draftKind || !selectedItem) return "Sybil";
     if (selectedItem.kind === "chat") {
-      if (selectedChat) return `${getChatTitle(selectedChat, selectedChat.messages)} — Sybil`;
+      if (selectedChat?.id === selectedItem.id) return `${getChatTitle(selectedChat, selectedChat.messages)} — Sybil`;
       if (selectedChatSummary) return `${getChatTitle(selectedChatSummary)} — Sybil`;
       return "Sybil";
     }
@@ -1631,6 +1741,7 @@ export default function App() {
   const handleCreateChat = () => {
     setError(null);
     setContextMenu(null);
+    draftKindRef.current = "chat";
     setDraftKind("chat");
     selectedItemRef.current = null;
     setSelectedItem(null);
@@ -1768,6 +1879,7 @@ export default function App() {
   const handleCreateSearch = () => {
     setError(null);
     setContextMenu(null);
+    draftKindRef.current = "search";
     setDraftKind("search");
     selectedItemRef.current = null;
     setSelectedItem(null);
@@ -1780,24 +1892,26 @@ export default function App() {
   };
 
   const selectAdjacentSidebarItem = (direction: -1 | 1) => {
-    if (!filteredSidebarItems.length) return;
+    if (!orderedSidebarItems.length) return;
 
     setError(null);
     setContextMenu(null);
+    draftKindRef.current = null;
     setDraftKind(null);
     setIsMobileSidebarOpen(false);
-    setSelectedItem((current) => {
-      const currentIndex = current
-        ? filteredSidebarItems.findIndex((item) => item.kind === current.kind && item.id === current.id)
-        : -1;
-      const fallbackIndex = direction > 0 ? 0 : filteredSidebarItems.length - 1;
-      const nextIndex =
-        currentIndex < 0
-          ? fallbackIndex
-          : Math.min(filteredSidebarItems.length - 1, Math.max(0, currentIndex + direction));
-      const nextItem = filteredSidebarItems[nextIndex];
-      return { kind: nextItem.kind, id: nextItem.id };
-    });
+    const current = selectedItemRef.current;
+    const currentIndex = current
+      ? orderedSidebarItems.findIndex((item) => item.kind === current.kind && item.id === current.id)
+      : -1;
+    const fallbackIndex = direction > 0 ? 0 : orderedSidebarItems.length - 1;
+    const nextIndex =
+      currentIndex < 0
+        ? fallbackIndex
+        : Math.min(orderedSidebarItems.length - 1, Math.max(0, currentIndex + direction));
+    const nextItem = orderedSidebarItems[nextIndex];
+    const target: SidebarSelection = { kind: nextItem.kind, id: nextItem.id };
+    selectedItemRef.current = target;
+    setSelectedItem(target);
   };
 
   useEffect(() => {
@@ -1836,7 +1950,7 @@ export default function App() {
 
     window.addEventListener("keydown", handleKeyDown);
     return () => window.removeEventListener("keydown", handleKeyDown);
-  }, [filteredSidebarItems, isAuthenticated, isQuickQuestionOpen]);
+  }, [isAuthenticated, isQuickQuestionOpen, orderedSidebarItems]);
 
   const getRenameSeedTitle = (chatId: string) => {
     if (selectedChat?.id === chatId) return getChatTitle(selectedChat, selectedChat.messages);
@@ -1847,6 +1961,7 @@ export default function App() {
   };
 
   const applyChatSummary = (updatedChat: ChatSummary, moveToFront = true) => {
+    supersedeCollectionLoad();
     setChats((current) => {
       const withoutExisting = current.filter((chat) => chat.id !== updatedChat.id);
       if (moveToFront) return [updatedChat, ...withoutExisting];
@@ -1862,6 +1977,8 @@ export default function App() {
       return {
         ...current,
         title: updatedChat.title,
+        parentChatId: updatedChat.parentChatId,
+        titleGenerationPending: updatedChat.titleGenerationPending,
         updatedAt: updatedChat.updatedAt,
         starred: updatedChat.starred,
         starredAt: updatedChat.starredAt,
@@ -1876,6 +1993,7 @@ export default function App() {
   };
 
   const applySearchSummary = (updatedSearch: SearchSummary, moveToFront = true) => {
+    supersedeCollectionLoad();
     setSearches((current) => {
       const withoutExisting = current.filter((search) => search.id !== updatedSearch.id);
       if (moveToFront) return [updatedSearch, ...withoutExisting];
@@ -1982,6 +2100,7 @@ export default function App() {
         });
         applyChatSummary(updatedChat);
       } else if (!selectedItem && draftKind !== "chat") {
+        draftKindRef.current = "chat";
         setDraftKind("chat");
       }
 
@@ -2002,11 +2121,28 @@ export default function App() {
   const openContextMenu = (event: MouseEvent, item: SidebarSelection) => {
     event.preventDefault();
     const menuWidth = 176;
-    const menuHeight = item.kind === "chat" ? 120 : 80;
+    const menuHeight = item.kind === "chat" ? 152 : 80;
     const padding = 8;
     const x = Math.min(event.clientX, window.innerWidth - menuWidth - padding);
     const y = Math.min(event.clientY, window.innerHeight - menuHeight - padding);
-    setContextMenu({ item, x: Math.max(padding, x), y: Math.max(padding, y) });
+    setContextMenu({ kind: "sidebar", item, x: Math.max(padding, x), y: Math.max(padding, y) });
+  };
+
+  const openMessageContextMenu = (event: MouseEvent, messageId: string) => {
+    if (selectedItem?.kind !== "chat" || messageId.startsWith("temp-")) return;
+    event.preventDefault();
+    const menuWidth = 176;
+    const menuHeight = 48;
+    const padding = 8;
+    const x = Math.min(event.clientX, window.innerWidth - menuWidth - padding);
+    const y = Math.min(event.clientY, window.innerHeight - menuHeight - padding);
+    setContextMenu({
+      kind: "message",
+      chatId: selectedItem.id,
+      messageId,
+      x: Math.max(padding, x),
+      y: Math.max(padding, y),
+    });
   };
 
   const handleRenameChatSubmit = async (event?: Event) => {
@@ -2039,18 +2175,23 @@ export default function App() {
     }
   };
 
+  const toggleChatFamilyStar = async (chatId: string) => {
+    const family = getChatFamilyItems(chatId);
+    const root = family.find((item) => item.parentChatId === null) ?? family[0];
+    if (!root) return;
+    applyChatSummary(await updateChatStar(root.id, !root.starred), false);
+  };
+
   const handleToggleStar = async (target: SidebarSelection) => {
-    const current = sidebarItems.find((item) => item.kind === target.kind && item.id === target.id);
-    const nextStarred = !current?.starred;
     setContextMenu(null);
     setError(null);
 
     try {
       if (target.kind === "chat") {
-        const updatedChat = await updateChatStar(target.id, nextStarred);
-        applyChatSummary(updatedChat, false);
+        await toggleChatFamilyStar(target.id);
       } else {
-        const updatedSearch = await updateSearchStar(target.id, nextStarred);
+        const current = sidebarItems.find((item) => item.kind === "search" && item.id === target.id);
+        const updatedSearch = await updateSearchStar(target.id, !current?.starred);
         applySearchSummary(updatedSearch, false);
       }
     } catch (err) {
@@ -2063,17 +2204,57 @@ export default function App() {
     }
   };
 
+  const handleForkChat = async (chatId: string, messageId?: string) => {
+    if (activeForkRequestRef.current !== null) return;
+    const requestId = ++forkRequestSequenceRef.current;
+    const selectionAtStart = selectedItemRef.current;
+    const draftKindAtStart = draftKindRef.current;
+    activeForkRequestRef.current = requestId;
+    setIsForkingChat(true);
+    setContextMenu(null);
+    setError(null);
+    try {
+      const forkedChat = await forkChat(chatId, messageId);
+      if (activeForkRequestRef.current !== requestId) return;
+      const target: SidebarSelection = { kind: "chat", id: forkedChat.id };
+      applyChatSummary(forkedChat);
+      const currentSelection = selectedItemRef.current;
+      const selectionUnchanged = selectionAtStart
+        ? currentSelection?.kind === selectionAtStart.kind && currentSelection.id === selectionAtStart.id
+        : currentSelection === null;
+      if (!selectionUnchanged || draftKindRef.current !== draftKindAtStart) return;
+
+      draftKindRef.current = null;
+      setDraftKind(null);
+      selectedItemRef.current = target;
+      setSelectedItem(target);
+      setSelectedChat(null);
+      setSelectedSearch(null);
+      setIsMobileSidebarOpen(false);
+    } catch (err) {
+      if (activeForkRequestRef.current !== requestId) return;
+      const message = err instanceof Error ? err.message : String(err);
+      if (message.includes("bearer token")) {
+        handleAuthFailure(message);
+      } else {
+        setError(message);
+      }
+    } finally {
+      if (activeForkRequestRef.current === requestId) {
+        activeForkRequestRef.current = null;
+        setIsForkingChat(false);
+      }
+    }
+  };
+
   const handleToggleChatSettingsStar = async () => {
     if (draftKind !== null || selectedItem?.kind !== "chat" || isTogglingChatSettingsStar) return;
-    const current = sidebarItems.find((item) => item.kind === "chat" && item.id === selectedItem.id);
-    const nextStarred = !current?.starred;
     setIsTogglingChatSettingsStar(true);
     setChatSettingsError(null);
     setError(null);
 
     try {
-      const updatedChat = await updateChatStar(selectedItem.id, nextStarred);
-      applyChatSummary(updatedChat, false);
+      await toggleChatFamilyStar(selectedItem.id);
     } catch (err) {
       const message = err instanceof Error ? err.message : String(err);
       if (message.includes("bearer token")) {
@@ -2087,9 +2268,13 @@ export default function App() {
   };
 
   const handleDeleteFromContextMenu = async () => {
-    if (!contextMenu || isItemRunning(contextMenu.item)) return;
+    if (!contextMenu || contextMenu.kind !== "sidebar" || isDeleteBlocked(contextMenu.item)) return;
     const target = contextMenu.item;
     setContextMenu(null);
+    if (isRootChat(target)) {
+      const confirmed = window.confirm("Delete this chat and all of its forks? This cannot be undone.");
+      if (!confirmed) return;
+    }
     setError(null);
     try {
       if (target.kind === "chat") {
@@ -2314,6 +2499,8 @@ export default function App() {
         ...(initialEnabledTools !== undefined ? { enabledTools: initialEnabledTools } : {}),
       });
       chatId = chat.id;
+      supersedeCollectionLoad();
+      draftKindRef.current = null;
       setDraftKind(null);
       setDraftChatTitle("");
       setChats((current) => {
@@ -2321,10 +2508,14 @@ export default function App() {
         return [chat, ...withoutExisting];
       });
       setWorkspaceItems((current) => upsertWorkspaceItem(current, chatWorkspaceItem(chat)));
-      setSelectedItem({ kind: "chat", id: chatId });
+      const createdChatSelection: SidebarSelection = { kind: "chat", id: chatId };
+      selectedItemRef.current = createdChatSelection;
+      setSelectedItem(createdChatSelection);
       setSelectedChat({
         id: chat.id,
         title: chat.title,
+        parentChatId: chat.parentChatId,
+        titleGenerationPending: chat.titleGenerationPending,
         createdAt: chat.createdAt,
         updatedAt: chat.updatedAt,
         starred: chat.starred,
@@ -2378,24 +2569,12 @@ export default function App() {
       },
     ];
 
-    const chatSummary = chats.find((chat) => chat.id === chatId);
-    const hasExistingTitle = Boolean(selectedChat?.id === chatId ? selectedChat.title?.trim() : chatSummary?.title?.trim());
-    if (!hasExistingTitle && !pendingTitleGenerationRef.current.has(chatId)) {
+    if (shouldRequestChatTitle(baseChat, pendingTitleGenerationRef.current.has(chatId))) {
       pendingTitleGenerationRef.current.add(chatId);
       const titleSeed = content || buildAttachmentSummary(attachments) || "Uploaded files";
       void suggestChatTitle({ chatId, content: titleSeed })
         .then((updatedChat) => {
-          setChats((current) =>
-            current.map((chat) => {
-              if (chat.id !== updatedChat.id) return chat;
-              return { ...chat, title: updatedChat.title, updatedAt: updatedChat.updatedAt };
-            })
-          );
-          setWorkspaceItems((current) => upsertWorkspaceItem(current, chatWorkspaceItem(updatedChat), false));
-          setSelectedChat((current) => {
-            if (!current || current.id !== updatedChat.id) return current;
-            return { ...current, title: updatedChat.title, updatedAt: updatedChat.updatedAt };
-          });
+          applyChatSummary(updatedChat, false);
         })
         .catch(() => {
           // ignore title suggestion errors so chat flow is not interrupted
@@ -2568,8 +2747,12 @@ export default function App() {
         title: query.slice(0, 80),
       });
       searchId = search.id;
+      supersedeCollectionLoad();
+      draftKindRef.current = null;
       setDraftKind(null);
-      setSelectedItem({ kind: "search", id: searchId });
+      const createdSearchSelection: SidebarSelection = { kind: "search", id: searchId };
+      selectedItemRef.current = createdSearchSelection;
+      setSelectedItem(createdSearchSelection);
       setSearches((current) => {
         const withoutExisting = current.filter((existing) => existing.id !== search.id);
         return [search, ...withoutExisting];
@@ -2964,6 +3147,8 @@ export default function App() {
     setIsStartingSearchChat(true);
     try {
       const chat = await createChatFromSearch(sourceSearch.id);
+      supersedeCollectionLoad();
+      draftKindRef.current = null;
       setDraftKind(null);
       replaceComposerDraft("");
       setPendingAttachments([]);
@@ -2972,10 +3157,14 @@ export default function App() {
         return [chat, ...withoutExisting];
       });
       setWorkspaceItems((current) => upsertWorkspaceItem(current, chatWorkspaceItem(chat)));
-      setSelectedItem({ kind: "chat", id: chat.id });
+      const createdChatSelection: SidebarSelection = { kind: "chat", id: chat.id };
+      selectedItemRef.current = createdChatSelection;
+      setSelectedItem(createdChatSelection);
       setSelectedChat({
         id: chat.id,
         title: chat.title,
+        parentChatId: chat.parentChatId,
+        titleGenerationPending: chat.titleGenerationPending,
         createdAt: chat.createdAt,
         updatedAt: chat.updatedAt,
         starred: chat.starred,
@@ -3123,6 +3312,8 @@ export default function App() {
         ],
       });
 
+      supersedeCollectionLoad();
+      draftKindRef.current = null;
       setDraftKind(null);
       replaceComposerDraft("");
       setPendingAttachments([]);
@@ -3134,10 +3325,14 @@ export default function App() {
         return [chat, ...withoutExisting];
       });
       setWorkspaceItems((current) => upsertWorkspaceItem(current, chatWorkspaceItem(chat)));
-      setSelectedItem({ kind: "chat", id: chat.id });
+      const createdChatSelection: SidebarSelection = { kind: "chat", id: chat.id };
+      selectedItemRef.current = createdChatSelection;
+      setSelectedItem(createdChatSelection);
       setSelectedChat({
         id: chat.id,
         title: chat.title,
+        parentChatId: chat.parentChatId,
+        titleGenerationPending: chat.titleGenerationPending,
         createdAt: chat.createdAt,
         updatedAt: chat.updatedAt,
         starred: chat.starred,
@@ -3218,9 +3413,7 @@ export default function App() {
   };
 
   const chatSettingsChatId = draftKind === null && selectedItem?.kind === "chat" ? selectedItem.id : null;
-  const chatSettingsStarred = chatSettingsChatId
-    ? sidebarItems.find((item) => item.kind === "chat" && item.id === chatSettingsChatId)?.starred ?? false
-    : false;
+  const chatSettingsStarred = chatSettingsChatId ? isSidebarTargetStarred({ kind: "chat", id: chatSettingsChatId }) : false;
 
   if (isCheckingSession) {
     return (
@@ -3335,7 +3528,18 @@ export default function App() {
                 <p className="px-3 pb-2 text-[11px] font-semibold text-violet-200/48">{section.label}</p>
                 {section.items.map((item) => {
                   const active = selectedItem?.kind === item.kind && selectedItem.id === item.id;
-                  const itemIsRunning = isItemRunning(item);
+                  const isForkChild = item.kind === "chat" && item.parentChatId !== null;
+                  const familyItems = item.kind === "chat" ? getChatFamilyItems(item.id) : [item];
+                  const itemIsRunning = familyItems.some((familyItem) => isItemRunning(familyItem));
+                  const itemIsStarred =
+                    familyItems.find((familyItem) => familyItem.parentChatId === null)?.starred ?? false;
+                  const itemUpdatedAt = familyItems.reduce(
+                    (newest, familyItem) =>
+                      new Date(familyItem.updatedAt).getTime() > new Date(newest).getTime()
+                        ? familyItem.updatedAt
+                        : newest,
+                    item.updatedAt
+                  );
                   const initiatedLabel = item.kind === "chat" && item.initiatedModel
                     ? `${getProviderLabel(item.initiatedProvider)}${item.initiatedProvider ? " · " : ""}${item.initiatedModel}`
                     : null;
@@ -3343,53 +3547,62 @@ export default function App() {
                     <button
                       key={`${item.kind}-${item.id}`}
                       className={cn(
-                        "mb-1 w-full rounded-lg border px-3 py-2.5 text-left transition",
+                        "mb-1 rounded-lg border text-left transition",
+                        isForkChild ? "ml-7 w-[calc(100%-1.75rem)] px-3 py-1.5" : "w-full px-3 py-2.5",
                         active
                           ? "border-violet-300/45 bg-[linear-gradient(135deg,hsl(258_86%_52%_/_0.58),hsl(277_78%_28%_/_0.55))] text-violet-50"
                           : "border-transparent text-violet-100/78 hover:border-violet-300/18 hover:bg-violet-400/10"
                       )}
                       onClick={() => {
                         setContextMenu(null);
+                        draftKindRef.current = null;
                         setDraftKind(null);
-                        setSelectedItem({ kind: item.kind, id: item.id });
+                        const target = { kind: item.kind, id: item.id } as SidebarSelection;
+                        selectedItemRef.current = target;
+                        setSelectedItem(target);
                         setIsMobileSidebarOpen(false);
                       }}
                       onContextMenu={(event) => openContextMenu(event, { kind: item.kind, id: item.id })}
                       type="button"
+                      title={isForkChild ? item.title : undefined}
                     >
-                      <div className="grid grid-cols-[auto_minmax(0,1fr)] gap-x-2 gap-y-1">
-                        <span
-                          className={cn(
-                            "flex h-5 w-5 shrink-0 items-center justify-center rounded-md border",
-                            active ? "border-cyan-200/35 bg-cyan-300/12 text-cyan-100" : "border-violet-300/18 text-violet-200/70"
-                          )}
-                        >
-                          {item.kind === "chat" ? <MessageSquare className="h-3.5 w-3.5" /> : <Search className="h-3.5 w-3.5" />}
-                        </span>
-                        <span className="flex min-w-0 flex-1 items-center gap-1.5">
-                          <span className="truncate text-sm font-semibold">{item.title}</span>
-                          {item.starred ? (
-                            <Star
-                              className={cn("h-3.5 w-3.5 shrink-0 fill-amber-300", active ? "text-amber-200" : "text-amber-300/90")}
-                              aria-label="Starred"
-                            />
-                          ) : null}
-                          {itemIsRunning ? (
-                            <LoaderCircle
-                              className={cn("h-3.5 w-3.5 shrink-0 animate-spin", active ? "text-cyan-100" : "text-cyan-300/90")}
-                              aria-label="Generating"
-                            />
-                          ) : null}
-                        </span>
-                        <span className="col-start-2 flex min-w-0 items-center gap-2">
-                          <span className="shrink-0 text-xs text-secondary-foreground/70">{formatDate(item.updatedAt)}</span>
-                          {initiatedLabel ? (
-                            <span className="ml-auto min-w-0 truncate text-right text-xs text-secondary-foreground/70">
-                              {initiatedLabel}
-                            </span>
-                          ) : null}
-                        </span>
-                      </div>
+                      {isForkChild ? (
+                        <span className="block truncate text-xs font-medium leading-5">{item.title}</span>
+                      ) : (
+                        <div className="grid grid-cols-[auto_minmax(0,1fr)] gap-x-2 gap-y-1">
+                          <span
+                            className={cn(
+                              "flex h-5 w-5 shrink-0 items-center justify-center rounded-md border",
+                              active ? "border-cyan-200/35 bg-cyan-300/12 text-cyan-100" : "border-violet-300/18 text-violet-200/70"
+                            )}
+                          >
+                            {item.kind === "chat" ? <MessageSquare className="h-3.5 w-3.5" /> : <Search className="h-3.5 w-3.5" />}
+                          </span>
+                          <span className="flex min-w-0 flex-1 items-center gap-1.5">
+                            <span className="truncate text-sm font-semibold">{item.title}</span>
+                            {itemIsStarred ? (
+                              <Star
+                                className={cn("h-3.5 w-3.5 shrink-0 fill-amber-300", active ? "text-amber-200" : "text-amber-300/90")}
+                                aria-label="Starred"
+                              />
+                            ) : null}
+                            {itemIsRunning ? (
+                              <LoaderCircle
+                                className={cn("h-3.5 w-3.5 shrink-0 animate-spin", active ? "text-cyan-100" : "text-cyan-300/90")}
+                                aria-label="Generating"
+                              />
+                            ) : null}
+                          </span>
+                          <span className="col-start-2 flex min-w-0 items-center gap-2">
+                            <span className="shrink-0 text-xs text-secondary-foreground/70">{formatDate(itemUpdatedAt)}</span>
+                            {initiatedLabel ? (
+                              <span className="ml-auto min-w-0 truncate text-right text-xs text-secondary-foreground/70">
+                                {initiatedLabel}
+                              </span>
+                            ) : null}
+                          </span>
+                        </div>
+                      )}
                     </button>
                   );
                 })}
@@ -3461,7 +3674,12 @@ export default function App() {
             }}
           >
             {!isSearchMode ? (
-              <ChatMessagesPanel messages={displayMessages} isLoading={isLoadingSelection} isSending={isSendingActiveChat} />
+              <ChatMessagesPanel
+                messages={displayMessages}
+                isLoading={isLoadingSelection}
+                isSending={isSendingActiveChat}
+                onMessageContextMenu={openMessageContextMenu}
+              />
             ) : (
               <SearchResultsPanel
                 search={selectedSearchForView}
@@ -3546,40 +3764,65 @@ export default function App() {
           style={{ left: contextMenu.x, top: contextMenu.y }}
           onContextMenu={(event) => event.preventDefault()}
         >
-          <button
-            type="button"
-            className="flex w-full items-center gap-2 rounded-md px-2 py-1.5 text-left text-sm text-violet-100 transition hover:bg-violet-400/12"
-            onClick={() => void handleToggleStar(contextMenu.item)}
-          >
-            <Star
-              className={cn(
-                "h-3.5 w-3.5",
-                sidebarItems.find((item) => item.kind === contextMenu.item.kind && item.id === contextMenu.item.id)?.starred
-                  ? "fill-amber-300 text-amber-300"
-                  : ""
-              )}
-            />
-            {sidebarItems.find((item) => item.kind === contextMenu.item.kind && item.id === contextMenu.item.id)?.starred ? "Unstar" : "Star"}
-          </button>
-          {contextMenu.item.kind === "chat" ? (
+          {contextMenu.kind === "message" ? (
             <button
               type="button"
-              className="flex w-full items-center gap-2 rounded-md px-2 py-1.5 text-left text-sm text-violet-100 transition hover:bg-violet-400/12"
-              onClick={() => openRenameChatDialog(contextMenu.item.id)}
+              className="flex w-full items-center gap-2 rounded-md px-2 py-1.5 text-left text-sm text-violet-100 transition hover:bg-violet-400/12 disabled:text-muted-foreground"
+              onClick={() => void handleForkChat(contextMenu.chatId, contextMenu.messageId)}
+              disabled={isForkingChat}
             >
-              <Pencil className="h-3.5 w-3.5" />
-              Rename
+              <GitFork className="h-3.5 w-3.5" />
+              Fork
             </button>
-          ) : null}
-          <button
-            type="button"
-            className="flex w-full items-center gap-2 rounded-md px-2 py-1.5 text-left text-sm text-rose-300 transition hover:bg-rose-500/12 disabled:text-muted-foreground"
-            onClick={() => void handleDeleteFromContextMenu()}
-            disabled={isItemRunning(contextMenu.item)}
-          >
-            <Trash2 className="h-3.5 w-3.5" />
-            Delete
-          </button>
+          ) : (
+            <>
+              <button
+                type="button"
+                className="flex w-full items-center gap-2 rounded-md px-2 py-1.5 text-left text-sm text-violet-100 transition hover:bg-violet-400/12"
+                onClick={() => void handleToggleStar(contextMenu.item)}
+              >
+                <Star
+                  className={cn(
+                    "h-3.5 w-3.5",
+                    isSidebarTargetStarred(contextMenu.item)
+                      ? "fill-amber-300 text-amber-300"
+                      : ""
+                  )}
+                />
+                {isSidebarTargetStarred(contextMenu.item) ? "Unstar" : "Star"}
+              </button>
+              {contextMenu.item.kind === "chat" ? (
+                <>
+                  <button
+                    type="button"
+                    className="flex w-full items-center gap-2 rounded-md px-2 py-1.5 text-left text-sm text-violet-100 transition hover:bg-violet-400/12 disabled:text-muted-foreground"
+                    onClick={() => void handleForkChat(contextMenu.item.id)}
+                    disabled={isForkingChat || isItemRunning(contextMenu.item)}
+                  >
+                    <GitFork className="h-3.5 w-3.5" />
+                    Fork
+                  </button>
+                  <button
+                    type="button"
+                    className="flex w-full items-center gap-2 rounded-md px-2 py-1.5 text-left text-sm text-violet-100 transition hover:bg-violet-400/12"
+                    onClick={() => openRenameChatDialog(contextMenu.item.id)}
+                  >
+                    <Pencil className="h-3.5 w-3.5" />
+                    Rename
+                  </button>
+                </>
+              ) : null}
+              <button
+                type="button"
+                className="flex w-full items-center gap-2 rounded-md px-2 py-1.5 text-left text-sm text-rose-300 transition hover:bg-rose-500/12 disabled:text-muted-foreground"
+                onClick={() => void handleDeleteFromContextMenu()}
+                disabled={isDeleteBlocked(contextMenu.item)}
+              >
+                <Trash2 className="h-3.5 w-3.5" />
+                {isRootChat(contextMenu.item) ? "Delete group" : "Delete"}
+              </button>
+            </>
+          )}
         </div>
       ) : null}
       {isChatSettingsOpen ? (

web/src/components/chat/chat-messages-panel.tsx

@@ -10,6 +10,7 @@ type Props = {
   messages: Message[];
   isLoading: boolean;
   isSending: boolean;
+  onMessageContextMenu?: (event: MouseEvent, messageId: string) => void;
 };
 
 type ToolLogMetadata = {
@@ -395,7 +396,7 @@ function ToolCallStack({
   );
 }
 
-export function ChatMessagesPanel({ messages, isLoading, isSending }: Props) {
+export function ChatMessagesPanel({ messages, isLoading, isSending, onMessageContextMenu }: Props) {
   const hasPendingAssistant = messages.some((message) => message.id.startsWith("temp-assistant-") && message.content.trim().length === 0);
   const renderItems = useMemo(() => buildMessageRenderItems(messages), [messages]);
   const toolCallMessageIDs = useMemo(() => getToolCallMessageIDs(messages), [messages]);
@@ -467,6 +468,11 @@ export function ChatMessagesPanel({ messages, isLoading, isSending }: Props) {
                     ? "rounded-xl border border-violet-300/24 bg-[linear-gradient(135deg,hsl(258_86%_48%_/_0.86),hsl(278_72%_29%_/_0.86))] px-4 py-3 text-sm leading-6 text-fuchsia-50 shadow-sm"
                     : "text-base leading-7 text-violet-50"
                 )}
+                onContextMenu={
+                  message.role === "assistant" && !message.id.startsWith("temp-") && onMessageContextMenu
+                    ? (event) => onMessageContextMenu(event, message.id)
+                    : undefined
+                }
               >
                 {attachments.length ? <ChatAttachmentList attachments={attachments} tone={isUser ? "user" : "assistant"} /> : null}
                 {isPendingAssistant ? (

web/src/lib/api.ts

@@ -1,6 +1,8 @@
 export type ChatSummary = {
   id: string;
   title: string | null;
+  parentChatId: string | null;
+  titleGenerationPending: boolean;
   createdAt: string;
   updatedAt: string;
   starred: boolean;
@@ -58,6 +60,8 @@ export type ToolCallEvent = {
 export type ChatDetail = {
   id: string;
   title: string | null;
+  parentChatId: string | null;
+  titleGenerationPending: boolean;
   createdAt: string;
   updatedAt: string;
   starred: boolean;
@@ -291,6 +295,14 @@ export async function getChat(chatId: string) {
   return data.chat;
 }
 
+export async function forkChat(chatId: string, messageId?: string) {
+  const data = await api<{ chat: ChatSummary }>(`/v1/chats/${chatId}/fork`, {
+    method: "POST",
+    body: JSON.stringify(messageId ? { messageId } : {}),
+  });
+  return data.chat;
+}
+
 export async function updateChatTitle(chatId: string, title: string) {
   const data = await api<{ chat: ChatSummary }>(`/v1/chats/${chatId}`, {
     method: "PATCH",

web/src/lib/chat-forking.ts

@@ -0,0 +1,82 @@
+export type ForkGroupingItem = {
+  kind: "chat" | "search";
+  id: string;
+  parentChatId: string | null;
+};
+
+type ChatTitleState = {
+  title: string | null;
+  titleGenerationPending: boolean;
+};
+
+type ForkPresentationItem = ForkGroupingItem & {
+  updatedAt: string;
+  starred: boolean;
+  starredAt: string | null;
+};
+
+export function groupForkedChatItems<T extends ForkGroupingItem>(items: T[]): T[][] {
+  const groups = new Map<string, { firstIndex: number; items: Array<{ item: T; index: number }> }>();
+
+  items.forEach((item, index) => {
+    const groupKey = item.kind === "chat" ? `chat:${item.parentChatId ?? item.id}` : `search:${item.id}`;
+    const group = groups.get(groupKey);
+    if (group) {
+      group.items.push({ item, index });
+      return;
+    }
+    groups.set(groupKey, { firstIndex: index, items: [{ item, index }] });
+  });
+
+  return [...groups.values()]
+    .sort((a, b) => a.firstIndex - b.firstIndex)
+    .map((group) =>
+      group.items
+        .sort((a, b) => {
+          const aIsRoot = a.item.kind === "chat" && a.item.parentChatId === null;
+          const bIsRoot = b.item.kind === "chat" && b.item.parentChatId === null;
+          if (aIsRoot !== bIsRoot) return aIsRoot ? -1 : 1;
+          return a.index - b.index;
+        })
+        .map(({ item }) => item)
+    );
+}
+
+export function filterSidebarItemsWithForkGroups<T extends ForkGroupingItem>(items: T[], matches: (item: T) => boolean): T[] {
+  return groupForkedChatItems(items)
+    .flatMap((group) => {
+      const matchingItems = group.filter(matches);
+      if (!matchingItems.length) return [];
+      const root = group.find((item) => item.kind === "chat" && item.parentChatId === null);
+      if (!root || matchingItems.includes(root)) return group;
+      return group.filter((item) => item === root || matchingItems.includes(item));
+    });
+}
+
+export function getForkGroupPresentation<T extends ForkPresentationItem>(groupItems: T[], allItems: T[]) {
+  const firstItem = groupItems[0];
+  if (!firstItem) return null;
+
+  const rootId = firstItem.kind === "chat" ? firstItem.parentChatId ?? firstItem.id : null;
+  const familyItems = rootId
+    ? allItems.filter((item) => item.kind === "chat" && (item.id === rootId || item.parentChatId === rootId))
+    : groupItems;
+  const updatedAt = familyItems.reduce(
+    (newest, item) => (new Date(item.updatedAt).getTime() > new Date(newest).getTime() ? item.updatedAt : newest),
+    firstItem.updatedAt
+  );
+  const starOwner = rootId
+    ? familyItems.find((item) => item.kind === "chat" && item.parentChatId === null)
+    : firstItem;
+
+  return {
+    updatedAt,
+    starred: starOwner?.starred ?? false,
+    starredAt: starOwner?.starredAt ?? null,
+  };
+}
+
+export function shouldRequestChatTitle(chat: ChatTitleState | null | undefined, isRequestInFlight: boolean) {
+  if (!chat || isRequestInFlight) return false;
+  return chat.titleGenerationPending || !chat.title?.trim();
+}

web/tests/chat-forking.test.mjs

@@ -0,0 +1,59 @@
+import assert from "node:assert/strict";
+import test from "node:test";
+import {
+  filterSidebarItemsWithForkGroups,
+  getForkGroupPresentation,
+  groupForkedChatItems,
+  shouldRequestChatTitle,
+} from "../src/lib/chat-forking.ts";
+
+const root = { kind: "chat", id: "root", parentChatId: null };
+const firstFork = { kind: "chat", id: "first-fork", parentChatId: "root" };
+const nestedFork = { kind: "chat", id: "nested-fork", parentChatId: "root" };
+const search = { kind: "search", id: "search", parentChatId: null };
+
+test("fork groups are positioned by their newest member and always render root first", () => {
+  assert.deepEqual(groupForkedChatItems([nestedFork, search, root, firstFork]), [
+    [root, nestedFork, firstFork],
+    [search],
+  ]);
+});
+
+test("sidebar filtering keeps a matching fork with its root", () => {
+  assert.deepEqual(
+    filterSidebarItemsWithForkGroups([search, root, firstFork, nestedFork], (item) => item.id === "nested-fork"),
+    [root, nestedFork]
+  );
+});
+
+test("sidebar filtering keeps all children when their root matches", () => {
+  assert.deepEqual(
+    filterSidebarItemsWithForkGroups([search, root, firstFork, nestedFork], (item) => item.id === "root"),
+    [root, firstFork, nestedFork]
+  );
+});
+
+test("a filtered family keeps its full-family date and root-owned star state", () => {
+  const fullFamily = [
+    { ...root, updatedAt: "2026-08-10T00:00:00.000Z", starred: true, starredAt: "2026-08-15T00:00:00.000Z" },
+    { ...firstFork, updatedAt: "2026-08-11T00:00:00.000Z", starred: false, starredAt: null },
+    { ...nestedFork, updatedAt: "2026-08-16T00:00:00.000Z", starred: false, starredAt: null },
+  ];
+  const filteredFamily = [fullFamily[0], fullFamily[1]];
+
+  assert.deepEqual(getForkGroupPresentation(filteredFamily, fullFamily), {
+    updatedAt: "2026-08-16T00:00:00.000Z",
+    starred: true,
+    starredAt: "2026-08-15T00:00:00.000Z",
+  });
+});
+
+test("a fork placeholder title is replaced on its first submitted prompt", () => {
+  assert.equal(shouldRequestChatTitle({ title: "Fork of original", titleGenerationPending: true }, false), true);
+  assert.equal(shouldRequestChatTitle({ title: "Generated title", titleGenerationPending: false }, false), false);
+});
+
+test("title generation remains compatible with untitled chats and deduplicates in-flight requests", () => {
+  assert.equal(shouldRequestChatTitle({ title: null, titleGenerationPending: false }, false), true);
+  assert.equal(shouldRequestChatTitle({ title: "Fork of original", titleGenerationPending: true }, true), false);
+});

web/tsconfig.tsbuildinfo

@@ -1 +1 @@
-{"root":["./src/App.tsx","./src/main.tsx","./src/pwa.ts","./src/root-router.tsx","./src/vite-env.d.ts","./src/components/sybil-character.tsx","./src/components/auth/auth-screen.tsx","./src/components/chat/chat-attachment-list.tsx","./src/components/chat/chat-composer.tsx","./src/components/chat/chat-messages-panel.tsx","./src/components/markdown/markdown-content.tsx","./src/components/search/search-results-panel.tsx","./src/components/ui/button.tsx","./src/components/ui/input.tsx","./src/components/ui/scroll-area.tsx","./src/components/ui/separator.tsx","./src/components/ui/textarea.tsx","./src/hooks/use-session-auth.ts","./src/lib/api.ts","./src/lib/chat-model-selection.ts","./src/lib/sidebar-selection.ts","./src/lib/utils.ts","./src/pages/search-route-page.tsx"],"version":"5.9.3"}
+{"root":["./src/App.tsx","./src/main.tsx","./src/pwa.ts","./src/root-router.tsx","./src/vite-env.d.ts","./src/components/sybil-character.tsx","./src/components/auth/auth-screen.tsx","./src/components/chat/chat-attachment-list.tsx","./src/components/chat/chat-composer.tsx","./src/components/chat/chat-messages-panel.tsx","./src/components/markdown/markdown-content.tsx","./src/components/search/search-results-panel.tsx","./src/components/ui/button.tsx","./src/components/ui/input.tsx","./src/components/ui/scroll-area.tsx","./src/components/ui/separator.tsx","./src/components/ui/textarea.tsx","./src/hooks/use-session-auth.ts","./src/lib/api.ts","./src/lib/chat-forking.ts","./src/lib/chat-model-selection.ts","./src/lib/sidebar-selection.ts","./src/lib/utils.ts","./src/pages/search-route-page.tsx"],"version":"5.9.3"}