// SessionManager.swift — Focus session state, native VLM screen analysis
// Screenshot capture → Gemini Vision API → apply results to UI + post to backend.
// No Python subprocess. No external process management.

import AppKit
import SwiftUI
import ScreenCaptureKit

/// Background monitoring vs focus session state.
enum MonitoringState {
    case monitoring      // VLM running, no focus session — Argus background mode
    case focusSession    // Linked to a specific task, tracking steps, distraction timer active
}

@Observable
@MainActor
final class SessionManager {
    static let shared = SessionManager()

    // MARK: - State

    var monitoringState: MonitoringState = .monitoring

    var activeSession: FocusSession?
    var activeTask: AppTask?
    var activeSteps: [Step] = []
    var currentStepIndex: Int = 0
    /// Computed for backward compatibility with UI bindings.
    var isSessionActive: Bool { monitoringState == .focusSession }
    var sessionStartDate: Date?
    var distractionCount: Int = 0
    var errorMessage: String?
    var isLoading: Bool = false

    // Resume card (shown in HUD, not system notification)
    var resumeCard: ResumeCard?
    var showingResumeCard: Bool = false

    // VLM / proactive agent
    var proactiveCard: ProactiveCard?
    var latestVlmSummary: String?
    var latestInferredTask: String?
    var latestAppName: String?
    var isExecuting: Bool = false
    var executorOutput: (title: String, content: String)?
    var monitoringError: String?

    // Nudge — shown in HUD as amber card, NOT system notification
    var nudgeMessage: String?
    @ObservationIgnored private var nudgeTimer: Task<Void, Never>?

    // Screenshot engine
    var isCapturing: Bool = false

    @ObservationIgnored private var captureTask: Task<Void, Never>?
    private let captureInterval: TimeInterval = 5.0

    // Two-tier history buffer (replaces flat frameBuffer + screenshotHistory)
    @ObservationIgnored private var historyBuffer = HistoryBuffer(imageMaxLen: 4, textMaxLen: 12)
    @ObservationIgnored private var savedFramesForExecutor: [Data] = []
    private let framesPerVLMCall = 4

    // App switch tracking
    @ObservationIgnored private var appSwitches: [(name: String, bundleId: String, time: Date)] = []
    @ObservationIgnored private var appSwitchObserver: (any NSObjectProtocol)?
    @ObservationIgnored private var lastApp: (name: String, bundleId: String) = ("", "")
    @ObservationIgnored private var lastAppEnteredAt: Date = Date()

    // Proactive card auto-dismiss timer
    @ObservationIgnored private var proactiveCardTimer: Task<Void, Never>?

    // Open sessions cache (for VLM session context injection)
    @ObservationIgnored private var openSessions: [OpenSession] = []
    @ObservationIgnored private var lastOpenSessionsFetch: Date?
    /// Adaptive: 10s during focus session, 30s during monitoring
    private var sessionsFetchInterval: TimeInterval { monitoringState == .focusSession ? 10.0 : 30.0 }

    // Cross-device sync: track last known active session to detect remote changes
    @ObservationIgnored private var lastKnownActiveSessionId: String?

    // Incomplete tasks cache (tasks without active sessions — for VLM task matching)
    @ObservationIgnored private var incompleteTasks: [AppTask] = []

    // Task caching (original's sophisticated matching)
    @ObservationIgnored private var cachedTasks: [AppTask] = []
    @ObservationIgnored private var lastTasksFetch: Date?

    // Inferred task stability tracking (for VLM-initiated task creation)
    @ObservationIgnored private var inferredTaskHistory: [String] = []
    private let stableTaskThreshold = 3

    // Notification dedup — fingerprint-based, prevents spam
    @ObservationIgnored private var lastFrictionFingerprint: String = ""

    // Session action dedup — tracks session IDs we've already shown cards for
    @ObservationIgnored private var handledSessionActions: Set<String> = []

    // Distraction timer (active only during focus session)
    @ObservationIgnored private var continuousOffTaskStart: Date?
    @ObservationIgnored private var consecutiveNudgeCount: Int = 0
    @ObservationIgnored private var lastNudgeSentAt: Date?
    private let maxConsecutiveNudges = 5

    /// Configurable distraction threshold (default 2 minutes).
    var distractionThresholdSeconds: TimeInterval {
        get {
            let stored = UserDefaults.standard.double(forKey: "lockInBro.distractionThreshold")
            return stored > 0 ? stored : 120
        }
        set { UserDefaults.standard.set(newValue, forKey: "lockInBro.distractionThreshold") }
    }

    private init() {}

    // MARK: - Computed

    var currentStep: Step? {
        guard currentStepIndex < activeSteps.count else { return nil }
        return activeSteps[currentStepIndex]
    }

    var completedCount: Int { activeSteps.filter(\.isDone).count }
    var totalSteps: Int { activeSteps.count }

    var sessionElapsed: TimeInterval {
        guard let start = sessionStartDate else { return 0 }
        return Date().timeIntervalSince(start)
    }

    // MARK: - Monitoring Lifecycle

    func stopMonitoring() {
        stopCapture()
        stopAppObserver()
        proactiveCardTimer?.cancel()
        proactiveCardTimer = nil
        nudgeTimer?.cancel()
        nudgeTimer = nil
        activeSession = nil
        activeTask = nil
        activeSteps = []
        monitoringState = .monitoring
        sessionStartDate = nil
        resumeCard = nil
        showingResumeCard = false
        proactiveCard = nil
        nudgeMessage = nil
        latestVlmSummary = nil
        latestInferredTask = nil
        latestAppName = nil
        isExecuting = false
        executorOutput = nil
        monitoringError = nil
        historyBuffer.clear()

        savedFramesForExecutor = []
        persistedSessionId = nil
        openSessions = []
        incompleteTasks = []
        cachedTasks = []
        lastTasksFetch = nil
        lastOpenSessionsFetch = nil
        inferredTaskHistory = []
        lastFrictionFingerprint = ""
        handledSessionActions = []
        distractionCount = 0
        continuousOffTaskStart = nil
        consecutiveNudgeCount = 0
        lastNudgeSentAt = nil
        lastKnownActiveSessionId = nil
    }

    /// Called once after login. Starts VLM monitoring only — no focus session.
    /// The VLM observes the screen and suggests resume/switch/start_new when appropriate.
    func startMonitoring() async {
        guard TokenStore.shared.token != nil else { return }
        guard !isCapturing else { return }

        monitoringError = nil

        if !CGPreflightScreenCaptureAccess() {
            CGRequestScreenCaptureAccess()
            monitoringError = "Screen Recording permission required — enable in System Settings → Privacy & Security → Screen Recording, then tap Retry"
            return
        }

        // End any stale active session FIRST — app always starts in monitoring mode.
        // The interrupted session will appear in open sessions for the VLM to suggest resuming.
        if let stale = try? await APIClient.shared.getActiveSession() {
            print("[Startup] Found stale session \(stale.id.prefix(8)) — interrupting. VLM will decide what to do.")
            _ = try? await APIClient.shared.endSession(sessionId: stale.id, status: "interrupted")
        }

        // Start VLM capture + app observer — monitoring mode only, no session
        startCapture()
        startAppObserver()

        // Fetch tasks and open sessions so VLM has context for matching
        await fetchTasksIfNeeded()
        await fetchOpenSessions()
        await fetchIncompleteTasks()
    }

    private func autoResumeSession(_ session: FocusSession) async {
        activeSession = session
        persistedSessionId = session.id
        monitoringState = .focusSession
        sessionStartDate = Date()
        distractionCount = 0
        nudgeMessage = nil
        historyBuffer.clear()

        continuousOffTaskStart = nil
        consecutiveNudgeCount = 0
        lastNudgeSentAt = nil

        if let taskId = session.taskId {
            do {
                if cachedTasks.isEmpty { await fetchTasksIfNeeded() }
                activeTask = cachedTasks.first(where: { $0.id == taskId })

                if activeTask == nil {
                    cachedTasks = try await APIClient.shared.getTasks()
                    lastTasksFetch = Date()
                    activeTask = cachedTasks.first(where: { $0.id == taskId })
                }

                if let task = activeTask {
                    let steps = try await APIClient.shared.getSteps(taskId: task.id)
                    activeSteps = steps.sorted { $0.sortOrder < $1.sortOrder }
                    currentStepIndex = activeSteps.firstIndex(where: { $0.isActive })
                        ?? activeSteps.firstIndex(where: { $0.status == "pending" })
                        ?? 0
                }
            } catch {}
        }

        // Build an informative resume summary for the HUD
        if let task = activeTask {
            let completed = activeSteps.filter(\.isDone).count
            let total = activeSteps.count
            var summary = "Resumed: \(task.title)"
            if total > 0 {
                summary += " (\(completed)/\(total) steps done)"
                if let step = currentStep?.title {
                    summary += " — next: \(step)"
                }
            }
            latestVlmSummary = summary
            latestInferredTask = task.title
        } else {
            let checkpoint = session.checkpoint?.vlmSummary ?? session.checkpoint?.lastActionSummary
            if let info = checkpoint, !info.isEmpty {
                latestVlmSummary = "Resumed session — \(info)"
            } else {
                latestVlmSummary = "Resumed session — monitoring your screen…"
            }
        }

        if !isCapturing { startCapture() }
        if appSwitchObserver == nil { startAppObserver() }
    }

    // MARK: - Open Sessions + Task List + Context

    private func fetchOpenSessions() async {
        guard TokenStore.shared.token != nil else { return }
        do {
            openSessions = try await APIClient.shared.getOpenSessions()
            lastOpenSessionsFetch = Date()
            detectCrossDeviceChanges()
        } catch {}
    }

    /// Fetch incomplete tasks that don't already have open sessions.
    /// These are tasks the user created (brain dump, manual, etc.) but hasn't started working on.
    private func fetchIncompleteTasks() async {
        guard TokenStore.shared.token != nil else { return }
        do {
            let allTasks = try await APIClient.shared.getTasks()
            let sessionTaskIds = Set(openSessions.compactMap(\.taskId))
            incompleteTasks = allTasks.filter { task in
                !task.isDone && !sessionTaskIds.contains(task.id)
            }
        } catch {}
    }

    /// Fetch tasks from the backend (cached for 30s).
    private func fetchTasksIfNeeded() async {
        if let last = lastTasksFetch, Date().timeIntervalSince(last) < 30 { return }
        do {
            cachedTasks = try await APIClient.shared.getTasks()
            lastTasksFetch = Date()
        } catch {}
    }

    private func maybeRefreshSessions() async {
        guard let lastFetch = lastOpenSessionsFetch else {
            await fetchOpenSessions()
            await fetchIncompleteTasks()
            return
        }
        if Date().timeIntervalSince(lastFetch) > sessionsFetchInterval {
            await fetchOpenSessions()
            await fetchIncompleteTasks()
        }
    }

    // MARK: - Cross-Device Session Sync

    /// Detect when another device ends a focus session we're tracking locally.
    /// Does NOT auto-resume — the VLM decides whether to suggest resume/switch/start_new.
    private func detectCrossDeviceChanges() {
        let serverActiveSession = openSessions.first(where: { $0.status == "active" })

        // Our local focus session was ended by another device → drop to monitoring
        if monitoringState == .focusSession,
           let localId = activeSession?.id,
           serverActiveSession?.id != localId {
            print("[CrossDevice] Session \(localId.prefix(8)) ended by another device")
            handleRemoteSessionEnd()
            return
        }

        // Track what's active on server (for context only — VLM decides what to do)
        lastKnownActiveSessionId = serverActiveSession?.id
    }

    /// Handle a session that was ended by another device.
    private func handleRemoteSessionEnd() {
        activeSession = nil
        activeTask = nil
        activeSteps = []
        monitoringState = .monitoring
        sessionStartDate = nil
        distractionCount = 0
        nudgeMessage = nil
        resumeCard = nil
        showingResumeCard = false
        proactiveCard = nil
        proactiveCardTimer?.cancel()
        proactiveCardTimer = nil
        nudgeTimer?.cancel()
        nudgeTimer = nil
        continuousOffTaskStart = nil
        consecutiveNudgeCount = 0
        lastNudgeSentAt = nil
        persistedSessionId = nil
        inferredTaskHistory = []
        latestVlmSummary = "Focus session ended on another device"
        // VLM capture continues in monitoring mode
    }

    private func formatSessionContext() -> String {
        var sections: [String] = []

        // Open sessions (active + interrupted)
        if !openSessions.isEmpty {
            let formatter = ISO8601DateFormatter()
            let lines: [String] = openSessions.map { s in
                let statusTag = "[\(s.status)]"
                let taskTitle = s.task?.title ?? "(no task)"
                var line = "  session_id=\"\(s.id)\" \(statusTag) \"\(taskTitle)\""

                let app = s.checkpoint?.activeApp ?? ""
                if !app.isEmpty { line += " — last in \(app)" }

                let file = s.checkpoint?.activeFile ?? ""
                if !file.isEmpty { line += "/\(file)" }

                let note = s.checkpoint?.lastActionSummary ?? ""
                if !note.isEmpty { line += ", \"\(note)\"" }

                if let endedAt = s.endedAt,
                   let date = formatter.date(from: endedAt) {
                    let minutes = Int(Date().timeIntervalSince(date) / 60)
                    if minutes > 0 { line += " (paused \(minutes)m ago)" }
                }
                return line
            }
            sections.append("Open sessions:\n" + lines.joined(separator: "\n"))
        }

        // Incomplete tasks without sessions (from brain dump, manual creation, etc.)
        if !incompleteTasks.isEmpty {
            let lines: [String] = incompleteTasks.prefix(10).map { t in
                var line = "  task_id=\"\(t.id)\" [\(t.status)] \"\(t.title)\""
                if let desc = t.description, !desc.isEmpty {
                    line += " — \(desc.prefix(80))"
                }
                return line
            }
            sections.append("Unstarted tasks (no session yet — use task_id in session_action if user is working on one):\n" + lines.joined(separator: "\n"))
        }

        if sections.isEmpty {
            return "(no open sessions or tasks — suggest start_new if user is actively working on something)"
        }
        return sections.joined(separator: "\n\n")
    }

    // MARK: - Notification Deduplication

    private func frictionFingerprint(_ friction: FrictionInfo) -> String {
        let labels = friction.proposedActions.map(\.label).sorted().joined(separator: "|")
        return "\(friction.type):\(labels)"
    }

    private func shouldNotify(friction: FrictionInfo) -> Bool {
        guard friction.isActionable else { return false }
        let fingerprint = frictionFingerprint(friction)
        if fingerprint == lastFrictionFingerprint { return false }
        lastFrictionFingerprint = fingerprint
        return true
    }

    // MARK: - Task Matching

    /// Find the best matching existing task by comparing inferred task + VLM summary against all non-done tasks.
    /// Uses keyword overlap scoring against task title, description, and tags.
    func findMatchingTask(for inferredTask: String, vlmSummary: String = "", appName: String = "") -> AppTask? {
        let stopWords: Set<String> = ["the", "a", "an", "in", "on", "to", "and", "or", "is", "for", "of", "with", "my",
                                       "this", "that", "user", "working", "screen", "currently", "appears", "be", "has",
                                       "are", "was", "been", "being", "it", "its", "at", "by", "from", "not", "but"]

        let combined = "\(inferredTask) \(vlmSummary) \(appName)".lowercased()
        let searchWords = Set(combined.split(separator: " ").map(String.init)).subtracting(stopWords)
        guard !searchWords.isEmpty else { return nil }

        var bestMatch: AppTask?
        var bestScore = 0

        for task in cachedTasks where task.status != "done" {
            var score = 0

            let titleWords = Set(task.title.lowercased().split(separator: " ").map(String.init)).subtracting(stopWords)
            score += searchWords.intersection(titleWords).count * 3

            if let desc = task.description?.lowercased() {
                let descWords = Set(desc.split(separator: " ").map(String.init)).subtracting(stopWords)
                score += searchWords.intersection(descWords).count
            }

            for tag in task.tags {
                if combined.contains(tag.lowercased()) {
                    score += 2
                }
            }

            if combined.contains(task.title.lowercased()) {
                score += 10
            }

            if score > bestScore {
                bestScore = score
                bestMatch = task
            }
        }

        return bestScore >= 4 ? bestMatch : nil
    }

    /// Try to match an inferred task string to an existing incomplete task by keyword overlap.
    /// Simpler version for VLM prompt injection.
    private func matchInferredTaskToExisting(_ inferredTask: String) -> AppTask? {
        let stopWords: Set<String> = ["the", "a", "an", "in", "on", "to", "and", "or", "is", "for", "of", "with"]
        let inferredWords = Set(inferredTask.lowercased().split(separator: " ").map(String.init))
            .subtracting(stopWords)
        guard !inferredWords.isEmpty else { return nil }

        var bestMatch: (task: AppTask, score: Int)?
        for task in incompleteTasks {
            let taskWords = Set(task.title.lowercased().split(separator: " ").map(String.init))
                .subtracting(stopWords)
            let overlap = inferredWords.intersection(taskWords).count
            if overlap >= 2, overlap > (bestMatch?.score ?? 0) {
                bestMatch = (task, overlap)
            }
        }
        return bestMatch?.task
    }

    // MARK: - Inferred Task Stability

    private func shouldSuggestNewSession(_ inferredTask: String) -> Bool {
        guard !inferredTask.isEmpty, !isSessionActive else {
            inferredTaskHistory = []
            return false
        }

        inferredTaskHistory.append(inferredTask)
        if inferredTaskHistory.count > stableTaskThreshold + 2 {
            inferredTaskHistory = Array(inferredTaskHistory.suffix(stableTaskThreshold + 2))
        }
        guard inferredTaskHistory.count >= stableTaskThreshold else { return false }

        let recent = Array(inferredTaskHistory.suffix(stableTaskThreshold))
        let stopWords: Set<String> = ["the", "a", "an", "in", "on", "to", "and", "or", "is", "for", "of", "with"]
        let firstWords = Set(recent[0].lowercased().split(separator: " ").map(String.init))
            .subtracting(stopWords)
        guard !firstWords.isEmpty else { return false }

        let allSimilar = recent.dropFirst().allSatisfy { task in
            let words = Set(task.lowercased().split(separator: " ").map(String.init))
            let overlap = firstWords.intersection(words)
            return Double(overlap.count) >= Double(firstWords.count) * 0.5
        }
        return allSimilar
    }

    // MARK: - VLM-Initiated Task Creation

    func createVLMTaskAndSession(inferredTask: String) async {
        isLoading = true
        errorMessage = nil
        do {
            if let stale = activeSession {
                _ = try? await APIClient.shared.endSession(sessionId: stale.id, status: "completed")
            }

            let task = try await APIClient.shared.createVLMTask(title: inferredTask)
            let plan = try? await APIClient.shared.planTask(taskId: task.id)
            let steps = (plan?.steps ?? []).sorted { $0.sortOrder < $1.sortOrder }

            let session = try await APIClient.shared.startSession(taskId: task.id)
            activeSession = session
            persistedSessionId = session.id
            activeTask = task
            activeSteps = steps
            currentStepIndex = 0
            monitoringState = .focusSession
            sessionStartDate = Date()
            distractionCount = 0
            inferredTaskHistory = []
            historyBuffer.clear()
    
            continuousOffTaskStart = nil
            consecutiveNudgeCount = 0
            lastNudgeSentAt = nil

            await fetchOpenSessions()

            stopCapture()
            startCapture()
            if appSwitchObserver == nil { startAppObserver() }
        } catch {
            errorMessage = error.localizedDescription
        }
        isLoading = false
    }

    // MARK: - Session Lifecycle

    private var persistedSessionId: String? {
        get { UserDefaults.standard.string(forKey: "lockInBro.lastSessionId") }
        set {
            if let v = newValue { UserDefaults.standard.set(v, forKey: "lockInBro.lastSessionId") }
            else { UserDefaults.standard.removeObject(forKey: "lockInBro.lastSessionId") }
        }
    }

    func startSession(task: AppTask?) async {
        isLoading = true
        errorMessage = nil
        do {
            var staleId: String? = activeSession?.id ?? persistedSessionId
            if staleId == nil {
                staleId = (try? await APIClient.shared.getActiveSession())?.id
            }
            if let id = staleId {
                _ = try? await APIClient.shared.endSession(sessionId: id, status: "completed")
            }

            let session = try await APIClient.shared.startSession(taskId: task?.id)
            activeSession = session
            persistedSessionId = session.id
            activeTask = task
            activeSteps = []
            currentStepIndex = 0
            monitoringState = .focusSession
            sessionStartDate = Date()
            distractionCount = 0
            nudgeMessage = nil
            historyBuffer.clear()
    
            continuousOffTaskStart = nil
            consecutiveNudgeCount = 0
            lastNudgeSentAt = nil

            if let task {
                let steps = try await APIClient.shared.getSteps(taskId: task.id)
                activeSteps = steps.sorted { $0.sortOrder < $1.sortOrder }
                currentStepIndex = activeSteps.firstIndex(where: { $0.isActive })
                    ?? activeSteps.firstIndex(where: { $0.status == "pending" })
                    ?? 0
            }

            stopCapture()
            startCapture()
            if appSwitchObserver == nil { startAppObserver() }
        } catch {
            errorMessage = error.localizedDescription
        }
        isLoading = false
    }

    /// Start a session attached to an existing task from the database.
    func startSessionWithExistingTask(_ task: AppTask) async {
        isLoading = true
        errorMessage = nil
        do {
            if let stale = activeSession {
                _ = try? await APIClient.shared.endSession(sessionId: stale.id, status: "completed")
            }

            let session = try await APIClient.shared.startSession(taskId: task.id)
            activeSession = session
            persistedSessionId = session.id
            activeTask = task
            monitoringState = .focusSession
            sessionStartDate = Date()
            distractionCount = 0
            inferredTaskHistory = []
            historyBuffer.clear()
    
            continuousOffTaskStart = nil
            consecutiveNudgeCount = 0
            lastNudgeSentAt = nil

            let steps = try await APIClient.shared.getSteps(taskId: task.id)
            activeSteps = steps.sorted { $0.sortOrder < $1.sortOrder }
            currentStepIndex = activeSteps.firstIndex(where: { $0.isActive })
                ?? activeSteps.firstIndex(where: { $0.status == "pending" })
                ?? 0

            await fetchOpenSessions()

            stopCapture()
            startCapture()
            if appSwitchObserver == nil { startAppObserver() }
        } catch {
            errorMessage = error.localizedDescription
        }
        isLoading = false
    }

    // MARK: - Context Checkpointing

    /// Save a context checkpoint before ending/interrupting a session.
    /// Captures the latest VLM state so the resume card has rich context later.
    private func saveCheckpoint(for sessionId: String) async {
        let stepId = currentStep?.id
        let summary = latestVlmSummary
        let inferred = latestInferredTask
        let app = latestAppName ?? NSWorkspace.shared.frontmostApplication?.localizedName

        var actionSummary = ""
        if let inferred, !inferred.isEmpty { actionSummary = inferred }
        if let summary, !summary.isEmpty {
            actionSummary += actionSummary.isEmpty ? summary : " — \(summary)"
        }

        let nextUp: String? = {
            guard let step = currentStep else { return nil }
            if step.isDone {
                return activeSteps.first(where: { $0.status == "pending" })?.title
            }
            return step.title
        }()

        try? await APIClient.shared.checkpointSession(
            sessionId: sessionId,
            currentStepId: stepId,
            lastActionSummary: actionSummary.isEmpty ? nil : String(actionSummary.prefix(500)),
            nextUp: nextUp,
            goal: activeTask?.description ?? activeTask?.title,
            activeApp: app,
            lastScreenshotAnalysis: summary,
            distractionCount: distractionCount
        )
    }

    func endSession(status: String = "completed") async {
        stopCapture()
        stopAppObserver()
        if let session = activeSession {
            await saveCheckpoint(for: session.id)
            _ = try? await APIClient.shared.endSession(sessionId: session.id, status: status)
        }
        activeSession = nil
        activeTask = nil
        activeSteps = []
        monitoringState = .monitoring
        sessionStartDate = nil
        resumeCard = nil
        showingResumeCard = false
        proactiveCard = nil
        nudgeMessage = nil
        latestVlmSummary = nil
        latestInferredTask = nil
        latestAppName = nil
        isExecuting = false
        executorOutput = nil
        proactiveCardTimer?.cancel()
        proactiveCardTimer = nil
        nudgeTimer?.cancel()
        nudgeTimer = nil
        historyBuffer.clear()

        savedFramesForExecutor = []
        persistedSessionId = nil
        inferredTaskHistory = []
        lastFrictionFingerprint = ""
        handledSessionActions = []
        continuousOffTaskStart = nil
        consecutiveNudgeCount = 0
        lastNudgeSentAt = nil
        lastKnownActiveSessionId = nil

        // Keep capture loop running for always-on monitoring
        if TokenStore.shared.token != nil {
            startCapture()
            startAppObserver()
        }
    }

    func fetchResumeCard() async {
        guard let session = activeSession else { return }
        do {
            let response = try await APIClient.shared.resumeSession(sessionId: session.id)
            resumeCard = response.resumeCard
            showingResumeCard = true
        } catch {
            errorMessage = error.localizedDescription
        }
    }

    func completeCurrentStep() async {
        guard let step = currentStep else { return }
        do {
            let updated = try await APIClient.shared.completeStep(stepId: step.id)
            if let idx = activeSteps.firstIndex(where: { $0.id == updated.id }) {
                activeSteps[idx] = updated
            }
            if let next = activeSteps.firstIndex(where: { $0.status == "pending" }) {
                currentStepIndex = next
            }
        } catch {
            errorMessage = error.localizedDescription
        }
    }

    // MARK: - Retry (HUD Retry button)

    func retryMonitoring() {
        monitoringError = nil
        historyBuffer.clear()

        stopCapture()
        startCapture()
        if appSwitchObserver == nil { startAppObserver() }
    }

    // MARK: - Nudge Lifecycle (shown in HUD)

    private func showNudge(_ message: String) {
        nudgeTimer?.cancel()
        distractionCount += 1
        withAnimation { nudgeMessage = message }

        nudgeTimer = Task { [weak self] in
            try? await Task.sleep(for: .seconds(12))
            guard !Task.isCancelled, let self else { return }
            await MainActor.run { withAnimation { self.nudgeMessage = nil } }
        }
    }

    func dismissNudge() {
        nudgeTimer?.cancel()
        nudgeTimer = nil
        withAnimation { nudgeMessage = nil }
    }

    // MARK: - Proactive Card Lifecycle

    private func markSessionActionHandled(_ card: ProactiveCard?) {
        if case .sessionAction(_, _, _, _, let sessionId, _) = card?.source, let sessionId {
            handledSessionActions.insert(sessionId)
        }
    }

    private func showProactiveCard(_ card: ProactiveCard, autoDismiss: Bool = true) {
        proactiveCardTimer?.cancel()
        withAnimation { proactiveCard = card }

        // Session action cards persist — they require user input.
        // Only friction/nudge cards auto-dismiss.
        if autoDismiss {
            proactiveCardTimer = Task { [weak self] in
                try? await Task.sleep(for: .seconds(30))
                guard !Task.isCancelled, let self else { return }
                await MainActor.run { self.dismissProactiveCard() }
            }
        }
    }

    func dismissProactiveCard() {
        markSessionActionHandled(proactiveCard)
        proactiveCardTimer?.cancel()
        proactiveCardTimer = nil
        withAnimation { proactiveCard = nil }
    }

    func approveProactiveCard(actionIndex: Int) {
        markSessionActionHandled(proactiveCard)
        proactiveCardTimer?.cancel()
        proactiveCardTimer = nil
        let card = proactiveCard
        withAnimation { proactiveCard = nil }

        switch card?.source {
        case .vlmFriction(_, _, let actions):
            guard actionIndex < actions.count else { return }
            let action = actions[actionIndex]
            isExecuting = true
            Task {
                do {
                    let geminiKey = UserDefaults.standard.string(forKey: "geminiApiKey") ?? ""
                    guard !geminiKey.isEmpty else {
                        isExecuting = false
                        executorOutput = (title: action.label, content: action.details ?? "Action approved.")
                        return
                    }
                    let client = GeminiVLMClient(apiKey: geminiKey)
                    // Send all buffered frames to the executor for vision context
                    var frames = historyBuffer.frameData
                    if let fresh = await captureScreen() { frames.append(fresh) }
                    savedFramesForExecutor = frames
                    let result = try await client.executeAction(
                        label: action.label,
                        details: action.details ?? "",
                        frames: frames,
                        onToolCall: { name, args in
                            print("[Executor] \(name): \(args)")
                        }
                    )
                    isExecuting = false
                    executorOutput = (title: action.label, content: result)
                    historyBuffer.setLastExecution("Completed: \(action.label). \(result.prefix(200))")
                } catch {
                    isExecuting = false
                    executorOutput = (title: action.label, content: action.details ?? "Couldn't complete automatically.")
                }
            }

        case .appSwitchLoop(let apps, _):
            isExecuting = true
            Task {
                do {
                    let geminiKey = UserDefaults.standard.string(forKey: "geminiApiKey") ?? ""
                    guard !geminiKey.isEmpty else {
                        isExecuting = false
                        executorOutput = (title: "App Switch Help", content: "No Gemini API key set.")
                        return
                    }
                    let client = GeminiVLMClient(apiKey: geminiKey)
                    let frames = historyBuffer.frameData
                    let label = "Help with \(apps.joined(separator: " ↔ ")) switching"
                    let details = """
                    The user is repeatedly switching between \(apps.joined(separator: " and ")). \
                    Look at the screenshots to understand what they're trying to do across these apps. \
                    If they're copying data between them, extract and format the data. \
                    If they're looking something up, find and summarize the answer. \
                    If they're comparing content, create a consolidated view. \
                    Use output() to show the result.
                    """
                    let result = try await client.executeAction(
                        label: label,
                        details: details,
                        frames: frames,
                        onToolCall: { name, args in
                            print("[Executor] \(name): \(args)")
                        }
                    )
                    isExecuting = false
                    executorOutput = (title: label, content: result)
                    historyBuffer.setLastExecution("Completed: \(label). \(result.prefix(200))")
                } catch {
                    isExecuting = false
                    executorOutput = (title: "App Switch Help", content: "Couldn't analyze — \(error.localizedDescription)")
                }
            }

        case .sessionAction(let type, let taskTitle, _, _, let sessionId, let taskId):
            let matchedTask = card?.matchedTask
            switch type {
            case "start_new":
                if actionIndex == 0 && matchedTask != nil {
                    Task { await startSessionWithExistingTask(matchedTask!) }
                } else if actionIndex == 0 && matchedTask == nil {
                    if let taskId, let existingTask = incompleteTasks.first(where: { $0.id == taskId }) {
                        Task { await startSession(task: existingTask) }
                    } else {
                        Task { await startSession(task: nil) }
                    }
                } else if actionIndex == 1 {
                    Task { await createVLMTaskAndSession(inferredTask: taskTitle) }
                } else if actionIndex == 2 {
                    Task { await startSession(task: nil) }
                }

            case "resume":
                guard let sessionId else { break }
                Task {
                    if let openSession = openSessions.first(where: { $0.id == sessionId }) {
                        let focusSession = FocusSession(
                            id: openSession.id,
                            userId: "",
                            taskId: openSession.taskId,
                            platform: openSession.platform,
                            startedAt: openSession.startedAt,
                            endedAt: nil,
                            status: "active",
                            checkpoint: nil
                        )
                        await autoResumeSession(focusSession)
                        await fetchResumeCard()
                    }
                }

            case "switch":
                guard let sessionId else { break }
                Task {
                    if let current = activeSession {
                        await saveCheckpoint(for: current.id)
                        _ = try? await APIClient.shared.endSession(sessionId: current.id, status: "interrupted")
                    }
                    if let openSession = openSessions.first(where: { $0.id == sessionId }) {
                        let focusSession = FocusSession(
                            id: openSession.id,
                            userId: "",
                            taskId: openSession.taskId,
                            platform: openSession.platform,
                            startedAt: openSession.startedAt,
                            endedAt: nil,
                            status: "active",
                            checkpoint: nil
                        )
                        await autoResumeSession(focusSession)
                    }
                }

            case "complete":
                guard let sessionId else { break }
                Task {
                    await saveCheckpoint(for: sessionId)
                    _ = try? await APIClient.shared.endSession(sessionId: sessionId, status: "completed")
                    if activeSession?.id == sessionId {
                        await endSession(status: "completed")
                    }
                    await fetchOpenSessions()
                }

            default:
                break
            }

        default:
            break
        }
    }

    // MARK: - App Switch Observer

    private func startAppObserver() {
        let current = NSWorkspace.shared.frontmostApplication
        lastApp = (current?.localizedName ?? "", current?.bundleIdentifier ?? "")
        lastAppEnteredAt = Date()
        appSwitches = []

        appSwitchObserver = NSWorkspace.shared.notificationCenter.addObserver(
            forName: NSWorkspace.didActivateApplicationNotification,
            object: nil,
            queue: .main
        ) { [weak self] notification in
            guard let app = notification.userInfo?[NSWorkspace.applicationUserInfoKey] as? NSRunningApplication
            else { return }
            Task { @MainActor [weak self] in self?.handleAppSwitch(app: app) }
        }
    }

    private func stopAppObserver() {
        if let observer = appSwitchObserver {
            NSWorkspace.shared.notificationCenter.removeObserver(observer)
            appSwitchObserver = nil
        }
        appSwitches = []
    }

    private func handleAppSwitch(app: NSRunningApplication) {
        let name = app.localizedName ?? "Unknown"
        let bundleId = app.bundleIdentifier ?? ""
        let now = Date()

        guard name != lastApp.name else { return }

        let duration = max(1, Int(now.timeIntervalSince(lastAppEnteredAt)))
        let prev = lastApp
        if let session = activeSession, !prev.name.isEmpty {
            Task {
                _ = try? await APIClient.shared.appActivity(
                    sessionId: session.id,
                    appBundleId: prev.bundleId,
                    appName: prev.name,
                    durationSeconds: duration
                )
            }
        }

        lastApp = (name, bundleId)
        lastAppEnteredAt = now

        appSwitches.append((name: name, bundleId: bundleId, time: now))
        if appSwitches.count > 30 { appSwitches.removeFirst() }

        guard isSessionActive, proactiveCard == nil else { return }
        if let loop = detectRepetitiveLoop() {
            showProactiveCard(ProactiveCard(source: .appSwitchLoop(apps: loop.apps, switchCount: loop.count)))
        }
    }

    private func detectRepetitiveLoop() -> (apps: [String], count: Int)? {
        let cutoff = Date().addingTimeInterval(-300)
        let recent = appSwitches.filter { $0.time > cutoff }.map(\.name)
        guard recent.count >= 6 else { return nil }
        let last6 = Array(recent.suffix(6))
        guard Set(last6).count == 2 else { return nil }
        for i in 1..<last6.count {
            if last6[i] == last6[i - 1] { return nil }
        }
        return (apps: Array(Set(last6)).sorted(), count: 3)
    }

    // MARK: - Screenshot Capture Loop

    private func startCapture() {
        guard !isCapturing else { return }
        isCapturing = true
        captureTask = Task { [weak self] in
            guard let self else { return }
            await self.captureAndAnalyze()
            while !Task.isCancelled {
                try? await Task.sleep(for: .seconds(self.captureInterval))
                guard !Task.isCancelled else { break }
                await self.captureAndAnalyze()
            }
        }
    }

    private func stopCapture() {
        captureTask?.cancel()
        captureTask = nil
        isCapturing = false
    }

    /// Capture one frame, buffer it, and call VLM every `framesPerVLMCall` frames.
    private func captureAndAnalyze() async {
        let t0 = Date()
        let ts = { "[t+\(String(format: "%.2f", Date().timeIntervalSince(t0)))s]" }

        print("\n[TIMING] ── captureAndAnalyze start at \(t0.formatted(.dateTime.hour().minute().second()))")

        // 1. Capture screenshot
        let tCapture = Date()
        guard let imageData = await captureScreen() else {
            print("[TIMING] captureScreen failed (no permission?)")
            return
        }
        print("[TIMING] \(ts()) captureScreen done — \(imageData.count / 1024)KB (\(String(format: "%.2f", Date().timeIntervalSince(tCapture)))s)")

        // 2. Push into the rolling buffer (oldest auto-evicted when full)
        historyBuffer.push(imageData: imageData)
        let bufferSize = historyBuffer.images.count
        let frameTimestamp = historyBuffer.images.last!.timestamp
        print("[TIMING] \(ts()) buffer=\(bufferSize)/\(framesPerVLMCall) frames")

        let geminiKey = UserDefaults.standard.string(forKey: "geminiApiKey") ?? ""

        // 2a. Upload this frame to Files API in the background so its URI is ready next cycle.
        // The 3 older frames in the rolling buffer were uploaded in previous cycles and already
        // have URIs — only the newest frame (just pushed) needs uploading now.
        if !geminiKey.isEmpty {
            let capturedData = imageData
            let capturedTs = frameTimestamp
            Task { @MainActor [weak self] in
                guard let self else { return }
                let client = GeminiVLMClient(apiKey: geminiKey)
                if let uri = try? await client.uploadFrame(capturedData) {
                    self.historyBuffer.updateFileUri(uri, forTimestamp: capturedTs)
                }
            }
        }

        // Warm-up: wait until buffer is full (~20s at 5s/frame) before first inference
        guard bufferSize >= framesPerVLMCall else {
            print("[TIMING] \(ts()) warming up buffer — skip VLM this cycle")
            return
        }

        guard !geminiKey.isEmpty else {
            print("[VLM] No Gemini API key set — skipping analysis")
            return
        }

        // 3. Snapshot the current rolling window for this VLM call
        let frames = historyBuffer.frameData
        let fileUris = historyBuffer.fileUris

        // 4. Refresh open sessions + build prompt context
        await maybeRefreshSessions()

        let tPrompt = Date()
        let client = GeminiVLMClient(apiKey: geminiKey)
        let windowTitle = NSWorkspace.shared.frontmostApplication?.localizedName ?? ""
        let historyCtx = historyBuffer.formatForPrompt()
        let sessionCtx = formatSessionContext()
        let lastOutputCtx = historyBuffer.formatLastOutput()
        let execCtx = historyBuffer.formatLastExecution()
        let totalBytes = frames.reduce(0) { $0 + $1.count }
        print("[TIMING] \(ts()) prompt context ready — \(frames.count) frames \(totalBytes / 1024)KB sessions=\(openSessions.count) (\(String(format: "%.3f", Date().timeIntervalSince(tPrompt)))s)")

        // 5. Gemini API call
        let tVlm = Date()
        print("[TIMING] \(ts()) → sending to Gemini…")
        do {
            let result = try await client.analyze(
                frames: frames,
                fileUris: fileUris,
                taskTitle: activeTask?.title ?? "",
                taskGoal: activeTask?.description ?? "",
                steps: activeSteps,
                windowTitle: windowTitle,
                historyContext: historyCtx,
                sessionContext: sessionCtx,
                lastOutputContext: lastOutputCtx,
                executionContext: execCtx
            )
            print("[TIMING] \(ts()) ← Gemini response received (\(String(format: "%.2f", Date().timeIntervalSince(tVlm)))s)")
            print("[VLM] on_task=\(result.onTask) notification=\(result.notification?.type ?? "none") friction=\(result.friction?.type ?? "none") | task: \(result.inferredTask ?? "") | \(result.vlmSummary ?? "")")

            // 6. Update history buffer
            let tApply = Date()
            if let summary = result.vlmSummary, !summary.isEmpty {
                historyBuffer.updateLastSummary(summary)
            }

            // Store full VLM result for self-refinement (encode key fields as JSON)
            let selfRefinementJSON = buildSelfRefinementJSON(result)
            historyBuffer.setLastOutput(selfRefinementJSON)

            // Tick execution age (clears after 3 iterations)
            historyBuffer.tickExecutionAge()

            // Save frames for executor context
            savedFramesForExecutor = frames

            monitoringError = nil
            applyDistractionResult(result)

            // Auto-link: if session is active but has NO task, try to match against database tasks
            if isSessionActive,
               activeTask == nil,
               proactiveCard == nil,
               let inferredTask = result.inferredTask, !inferredTask.isEmpty {
                await fetchTasksIfNeeded()
                if let matched = findMatchingTask(
                    for: inferredTask,
                    vlmSummary: result.vlmSummary ?? "",
                    appName: result.appName ?? ""
                ) {
                    var card = ProactiveCard(source: .sessionAction(
                        type: "start_new",
                        taskTitle: matched.title,
                        checkpoint: "",
                        reason: "Want to start a focus session for \"\(matched.title)\"?",
                        sessionId: nil,
                        taskId: nil
                    ))
                    card.matchedTask = matched
                    showProactiveCard(card, autoDismiss: false)
                }
            }

            // Fallback: if VLM didn't suggest a session but task is stable, suggest start_new
            if result.sessionAction?.type == "none" || result.sessionAction == nil,
               !isSessionActive,
               let inferredTask = result.inferredTask, !inferredTask.isEmpty,
               shouldSuggestNewSession(inferredTask),
               proactiveCard == nil {
                await fetchTasksIfNeeded()
                let inferredWork = inferredTask
                let matched = findMatchingTask(
                    for: inferredWork,
                    vlmSummary: result.vlmSummary ?? "",
                    appName: result.appName ?? ""
                )
                let matchedTaskFromIncomplete = matchInferredTaskToExisting(inferredWork)
                let reason: String
                if let matched {
                    reason = "Want to start a focus session for \"\(matched.title)\"?"
                } else {
                    reason = "You've been working on this — want to start a focus session?"
                }
                var card = ProactiveCard(source: .sessionAction(
                    type: "start_new",
                    taskTitle: matched?.title ?? inferredWork,
                    checkpoint: "",
                    reason: reason,
                    sessionId: nil,
                    taskId: matchedTaskFromIncomplete?.id
                ))
                card.matchedTask = matched
                showProactiveCard(card, autoDismiss: false)
            }
            print("[TIMING] \(ts()) applyDistractionResult done (\(String(format: "%.3f", Date().timeIntervalSince(tApply)))s)")

            // 7. Backend post + live checkpoint (fire-and-forget)
            if let session = activeSession {
                let stepId = currentStep?.id
                let app = latestAppName
                let summary = latestVlmSummary
                let dCount = distractionCount
                print("[TIMING] \(ts()) posting result + checkpoint to backend…")
                Task {
                    let tBackend = Date()
                    try? await APIClient.shared.postAnalysisResult(result, sessionId: session.id)
                    // Keep checkpoint fresh so resume card always has latest context
                    try? await APIClient.shared.checkpointSession(
                        sessionId: session.id,
                        currentStepId: stepId,
                        activeApp: app,
                        lastScreenshotAnalysis: summary,
                        distractionCount: dCount
                    )
                    print("[TIMING] backend POST + checkpoint done (\(String(format: "%.2f", Date().timeIntervalSince(tBackend)))s)")
                }
            }

            print("[TIMING] ── total cycle: \(String(format: "%.2f", Date().timeIntervalSince(t0)))s")
        } catch {
            print("[TIMING] \(ts()) ✗ Gemini error after \(String(format: "%.2f", Date().timeIntervalSince(tVlm)))s: \(error)")
        }
    }

    /// Build a concise JSON string of the VLM result for self-refinement context.
    private func buildSelfRefinementJSON(_ result: DistractionAnalysisResponse) -> String {
        var dict: [String: Any] = [
            "on_task": result.onTask,
            "confidence": result.confidence
        ]
        if let task = result.inferredTask { dict["inferred_task"] = task }
        if let summary = result.vlmSummary { dict["vlm_summary"] = summary }
        if let friction = result.friction {
            dict["friction_type"] = friction.type
            if let desc = friction.description { dict["friction_description"] = desc }
        }
        if let sa = result.sessionAction {
            dict["session_action"] = sa.type
        }
        if let app = result.appName { dict["app_name"] = app }

        guard let data = try? JSONSerialization.data(withJSONObject: dict, options: [.sortedKeys]),
              let str = String(data: data, encoding: .utf8) else {
            return result.vlmSummary ?? ""
        }
        return str
    }

    // MARK: - Screen Capture

    private func captureScreen() async -> Data? {
        guard CGPreflightScreenCaptureAccess() else { return nil }
        do {
            let t0 = Date()
            let content = try await SCShareableContent.current
            print("[TIMING]   captureScreen: SCShareableContent \(String(format: "%.3f", Date().timeIntervalSince(t0)))s")

            guard let display = content.displays.first else { return nil }
            let config = SCStreamConfiguration()
            config.width = 1280
            config.height = 720
            let filter = SCContentFilter(display: display, excludingWindows: [])

            let t1 = Date()
            let image = try await SCScreenshotManager.captureImage(
                contentFilter: filter, configuration: config)
            print("[TIMING]   captureScreen: captureImage \(String(format: "%.3f", Date().timeIntervalSince(t1)))s")

            let t2 = Date()
            let jpeg = cgImageToJPEG(image)
            print("[TIMING]   captureScreen: JPEG encode \(String(format: "%.3f", Date().timeIntervalSince(t2)))s → \((jpeg?.count ?? 0) / 1024)KB")
            return jpeg
        } catch {
            print("[TIMING]   captureScreen: error \(error)")
            return nil
        }
    }

    private func cgImageToJPEG(_ image: CGImage) -> Data? {
        let nsImage = NSImage(cgImage: image, size: .zero)
        guard let tiff = nsImage.tiffRepresentation,
              let bitmap = NSBitmapImageRep(data: tiff),
              let jpeg = bitmap.representation(using: .jpeg, properties: [.compressionFactor: 0.5])
        else { return nil }
        return jpeg
    }

    // MARK: - Apply VLM Result

    private func applyDistractionResult(_ result: DistractionAnalysisResponse) {
        if let summary = result.vlmSummary { latestVlmSummary = summary }
        if let task = result.inferredTask, !task.isEmpty { latestInferredTask = task }
        if let app = result.appName, !app.isEmpty { latestAppName = app }

        // Apply step side-effects
        for completedId in result.stepsCompleted {
            if let idx = activeSteps.firstIndex(where: { $0.id == completedId }) {
                activeSteps[idx].status = "done"
            }
        }
        if let note = result.checkpointNoteUpdate,
           let stepId = result.currentStepId,
           let idx = activeSteps.firstIndex(where: { $0.id == stepId }) {
            activeSteps[idx].checkpointNote = note
        }
        if let stepId = result.currentStepId,
           let idx = activeSteps.firstIndex(where: { $0.id == stepId }) {
            currentStepIndex = idx
        }

        // Trust VLM's explicit notification decision
        switch result.notification?.type {
        case "friction":
            if let friction = result.friction {
                if friction.isResumption {
                    // Task resumption → show resume card (skip if already handled)
                    if let sa = result.sessionAction, sa.type == "resume", let sessionId = sa.sessionId,
                       !handledSessionActions.contains(sessionId) {
                        showProactiveCard(ProactiveCard(source: .sessionAction(
                            type: "resume",
                            taskTitle: result.inferredTask ?? "Previous task",
                            checkpoint: friction.description ?? "",
                            reason: sa.reason ?? "You appear to be returning to this task.",
                            sessionId: sessionId,
                            taskId: nil
                        )))
                    } else {
                        Task { await fetchResumeCard() }
                    }
                } else if shouldNotify(friction: friction), proactiveCard == nil {
                    showProactiveCard(ProactiveCard(source: .vlmFriction(
                        frictionType: friction.type,
                        description: friction.description,
                        actions: friction.proposedActions
                    )))
                }
            }
        case "nudge":
            // Only show nudges during active focus sessions — not in monitoring mode.
            // In monitoring mode the VLM should suggest start_new/resume, not nag.
            if isSessionActive, let nudge = result.notification?.message, !nudge.isEmpty {
                showNudge(nudge)
            }
        default:
            break
        }

        // Handle session lifecycle suggestions
        if let sa = result.sessionAction, sa.type != "none" {
            switch sa.type {
            case "start_new" where !isSessionActive && proactiveCard == nil:
                let inferredWork = result.inferredTask ?? "your current work"
                let matchedTaskId = sa.taskId ?? matchInferredTaskToExisting(inferredWork)?.id
                let matchedTitle = (matchedTaskId != nil ? incompleteTasks.first(where: { $0.id == matchedTaskId })?.title : nil) ?? inferredWork
                // Also try the sophisticated matcher
                var card = ProactiveCard(source: .sessionAction(
                    type: "start_new",
                    taskTitle: matchedTitle,
                    checkpoint: "",
                    reason: sa.reason ?? "You appear to be actively working — want to start a focus session?",
                    sessionId: nil,
                    taskId: matchedTaskId
                ))
                card.matchedTask = findMatchingTask(
                    for: inferredWork,
                    vlmSummary: result.vlmSummary ?? "",
                    appName: result.appName ?? ""
                )
                showProactiveCard(card, autoDismiss: false)
            case "resume" where proactiveCard == nil && !handledSessionActions.contains(sa.sessionId ?? ""):
                let taskTitle = openSessions.first(where: { $0.id == sa.sessionId })?.task?.title
                    ?? result.inferredTask ?? "Previous task"
                let checkpoint = openSessions.first(where: { $0.id == sa.sessionId })?
                    .checkpoint?.lastActionSummary ?? ""
                showProactiveCard(ProactiveCard(source: .sessionAction(
                    type: "resume",
                    taskTitle: taskTitle,
                    checkpoint: checkpoint,
                    reason: sa.reason ?? "You appear to be returning to this task.",
                    sessionId: sa.sessionId,
                    taskId: nil
                )))
            case "switch" where proactiveCard == nil && !handledSessionActions.contains(sa.sessionId ?? ""):
                let taskTitle = openSessions.first(where: { $0.id == sa.sessionId })?.task?.title
                    ?? result.inferredTask ?? "Another task"
                showProactiveCard(ProactiveCard(source: .sessionAction(
                    type: "switch",
                    taskTitle: taskTitle,
                    checkpoint: "",
                    reason: sa.reason ?? "You seem to have moved to a different task.",
                    sessionId: sa.sessionId,
                    taskId: nil
                )), autoDismiss: false)
            case "complete" where proactiveCard == nil:
                let taskTitle = activeTask?.title ?? result.inferredTask ?? "Current task"
                showProactiveCard(ProactiveCard(source: .sessionAction(
                    type: "complete",
                    taskTitle: taskTitle,
                    checkpoint: "",
                    reason: sa.reason ?? "It looks like you've finished this task.",
                    sessionId: sa.sessionId ?? activeSession?.id,
                    taskId: nil
                )), autoDismiss: false)
            default:
                break
            }
        }

        // MARK: Distraction Timer (focus session only)
        if monitoringState == .focusSession {
            if result.onTask {
                if continuousOffTaskStart != nil {
                    print("[Distraction] User back on task — timer reset (was \(consecutiveNudgeCount) nudges)")
                }
                continuousOffTaskStart = nil
                consecutiveNudgeCount = 0
            } else {
                if continuousOffTaskStart == nil {
                    continuousOffTaskStart = Date()
                }

                let offTaskDuration = Date().timeIntervalSince(continuousOffTaskStart!)
                let canNudge = lastNudgeSentAt == nil ||
                    Date().timeIntervalSince(lastNudgeSentAt!) >= distractionThresholdSeconds

                if offTaskDuration >= distractionThresholdSeconds && canNudge {
                    if consecutiveNudgeCount < maxConsecutiveNudges {
                        consecutiveNudgeCount += 1
                        lastNudgeSentAt = Date()
                        continuousOffTaskStart = Date()

                        let nudgeContent = buildNudgeContent()
                        showNudge(nudgeContent.body)

                        // Backend push to all other devices
                        if let sessionId = activeSession?.id {
                            Task {
                                _ = try? await APIClient.shared.sendNudge(
                                    sessionId: sessionId,
                                    title: nudgeContent.title,
                                    body: nudgeContent.body,
                                    nudgeNumber: consecutiveNudgeCount,
                                    lastStep: nudgeContent.lastStep,
                                    nextStep: nudgeContent.nextStep
                                )
                            }
                        }
                        print("[Distraction] Nudge \(consecutiveNudgeCount)/\(maxConsecutiveNudges) sent")
                    }

                    if consecutiveNudgeCount >= maxConsecutiveNudges {
                        print("[Distraction] 5 nudges reached — auto-stopping session")
                        Task { await endSession(status: "auto_stopped") }
                    }
                }
            }
        }
    }

    // MARK: - Nudge Content

    private func buildNudgeContent() -> (title: String, body: String, lastStep: String?, nextStep: String?) {
        let lastCompleted = activeSteps.last(where: { $0.isDone })?.title
        let nextStepTitle = currentStep?.title

        let title = "Hey, quick check-in!"
        var body = ""
        if let last = lastCompleted { body += "Done: \(last). " }
        if let next = nextStepTitle { body += "Next up: \(next). " }
        body += "You got this!"

        return (title, body, lastCompleted, nextStepTitle)
    }
}