fix: settings form alignment — grouped form, aligned labels

Add ReturnsList (newest-first, max 8, click-to-Finder, hidden when empty)
and SettingsView (hotkey row, folder Choose… via FolderSettings + AppModel
seam mutators, async updateWatchFolder(url) only).

Sources/Shotdeck/AppModel.swift

@@ -0,0 +1,265 @@
+import AppKit
+import Carbon.HIToolbox
+import Foundation
+import Observation
+import SwiftUI
+import ShotdeckCore
+
+@MainActor
+public protocol SendCapable: AnyObject {
+    func send(anchor: NSView?) async
+}
+
+@MainActor
+public protocol SettingsWindowPresenting: AnyObject {
+    func presentSettingsWindow()
+}
+
+@MainActor
+public protocol ReturnsSectionProviding: AnyObject {
+    @ViewBuilder func returnsSection() -> AnyView
+}
+
+@MainActor
+@Observable
+public final class AppModel {
+    public private(set) var session: CaptureSession
+    public private(set) var region: CaptureRegion?
+    public private(set) var screenRecordingGranted: Bool
+    public private(set) var allReturns: [ReturnedDocument] = []
+    public private(set) var commentedReturns: [ReturnedDocument] = []
+    public private(set) var statusLine: String?
+    public private(set) var isCapturing: Bool = false
+    public private(set) var isSending: Bool = false
+    public private(set) var outboxDisplayName: String
+    public private(set) var watchFolderDisplayName: String
+    /// Live outbox; WP-4b reads this (not `paths.outbox`) so Settings folder changes take effect.
+    public private(set) var outboxURL: URL
+    /// Live watch folder; WP-4c updates this alongside `ReturnWatcher.updateWatchFolder`.
+    public private(set) var watchFolderURL: URL
+
+    let paths: AppSupportPaths
+    let spool: SpoolStore
+    let composer: PDFComposer
+    let capturer: ScreenCapturer
+    let hotkeys: HotkeyCenter
+    let picker: RegionPickerController
+    let ledger: ReturnLedger
+    let watcher: ReturnWatcher
+
+    public init(
+        paths: AppSupportPaths,
+        spool: SpoolStore,
+        composer: PDFComposer,
+        capturer: ScreenCapturer,
+        hotkeys: HotkeyCenter,
+        picker: RegionPickerController,
+        ledger: ReturnLedger,
+        watcher: ReturnWatcher
+    ) {
+        self.paths = paths
+        self.spool = spool
+        self.composer = composer
+        self.capturer = capturer
+        self.hotkeys = hotkeys
+        self.picker = picker
+        self.ledger = ledger
+        self.watcher = watcher
+        self.session = CaptureSession(
+            id: UUID(),
+            createdAt: Date(),
+            state: .open,
+            captures: [],
+            pdfFileName: nil
+        )
+        self.region = nil
+        self.screenRecordingGranted = ScreenCapturer.isScreenRecordingGranted
+        // Seeded from FolderSettings.resolve() via resolvedAppSupportPaths — never .standard().
+        let folders = FolderSettings.resolve()
+        self.outboxURL = folders.outbox
+        self.watchFolderURL = folders.watch
+        self.outboxDisplayName = folders.outbox.lastPathComponent
+        self.watchFolderDisplayName = folders.watch.lastPathComponent
+    }
+
+    // MARK: Seam mutators — the only way a WP-4b/4c extension changes state.
+
+    func setStatus(_ text: String?) { statusLine = text }
+    func setSending(_ value: Bool) { isSending = value }
+    func setCapturing(_ value: Bool) { isCapturing = value }
+    func replaceSession(_ new: CaptureSession) { session = new }
+    func replaceRegion(_ new: CaptureRegion?) { region = new }
+    func setReturns(all: [ReturnedDocument], commented: [ReturnedDocument]) {
+        allReturns = all
+        commentedReturns = commented
+    }
+    func setFolderDisplayNames(outbox: String, watch: String) {
+        outboxDisplayName = outbox
+        watchFolderDisplayName = watch
+    }
+    func setFolderURLs(outbox: URL, watch: URL) {
+        outboxURL = outbox
+        watchFolderURL = watch
+        setFolderDisplayNames(outbox: outbox.lastPathComponent, watch: watch.lastPathComponent)
+    }
+
+    public var iconState: MenuIconState {
+        if !screenRecordingGranted { return .recordingMissing }
+        if isCapturing { return .capturing }
+        if region == nil { return .noRegion }
+        if session.captures.isEmpty { return .regionEmpty }
+        return .hasCaptures(session.captures.count)
+    }
+
+    public func bootstrap() async {
+        if let data = UserDefaults.standard.data(forKey: CaptureRegion.defaultsKey),
+           let decoded = try? JSONDecoder().decode(CaptureRegion.self, from: data),
+           decoded.isStillValid {
+            replaceRegion(decoded)
+        }
+
+        do {
+            let recovered = try await spool.currentSession()
+            replaceSession(recovered)
+        } catch {
+            setStatus((error as? ShotdeckError)?.errorDescription ?? "Could not open the spool.")
+        }
+
+        do {
+            let initial = try await ledger.all()
+            let commented = try await ledger.commented()
+            setReturns(all: initial, commented: commented)
+        } catch {
+            // Empty ledger on first run is not an error.
+        }
+
+        do {
+            try await watcher.start { [weak self] _ in
+                Task { @MainActor in
+                    guard let self else { return }
+                    let all = (try? await self.ledger.all()) ?? []
+                    let commented = (try? await self.ledger.commented()) ?? []
+                    self.setReturns(all: all, commented: commented)
+                }
+            }
+        } catch {
+            setStatus((error as? ShotdeckError)?.errorDescription ?? "Could not watch the return folder.")
+        }
+
+        let registered = hotkeys.register(
+            id: "capture",
+            keyCode: UInt32(kVK_ANSI_2),
+            modifiers: UInt32(optionKey | shiftKey)
+        ) { [weak self] in
+            Task { await self?.captureNow() }
+        }
+        if !registered {
+            setStatus("⌥⇧2 is already used by another app — capture only works from the menu.")
+        }
+    }
+
+    public func captureNow() async {
+        guard !isCapturing else { return }
+        setCapturing(true)
+        defer { setCapturing(false) }
+
+        var target = region
+        if target == nil {
+            target = await withCheckedContinuation { (cont: CheckedContinuation<CaptureRegion?, Never>) in
+                picker.pick { picked in cont.resume(returning: picked) }
+            }
+            guard let picked = target else {
+                setStatus("No region selected.")
+                return
+            }
+            persistRegion(picked)
+        }
+        guard let region = target else { return }
+
+        do {
+            let image = try await capturer.capture(region)
+            let capture = try await spool.append(
+                pngData: image.pngData,
+                pixelWidth: image.pixelWidth,
+                pixelHeight: image.pixelHeight,
+                scale: image.scale,
+                capturedAt: Date()
+            )
+            replaceSession(try await spool.currentSession())
+            setStatus("Captured page \(capture.sequence).")
+        } catch {
+            screenRecordingGranted = ScreenCapturer.isScreenRecordingGranted
+            setStatus((error as? ShotdeckError)?.errorDescription ?? "The screenshot could not be taken.")
+        }
+    }
+
+    public func rePickRegion() async {
+        let picked = await withCheckedContinuation { (cont: CheckedContinuation<CaptureRegion?, Never>) in
+            picker.pick { cont.resume(returning: $0) }
+        }
+        guard let picked else { return }
+        persistRegion(picked)
+        setStatus("Region set: \(Int(picked.rect.width)) × \(Int(picked.rect.height)).")
+    }
+
+    public func removeCapture(id: UUID) async {
+        do {
+            // D-11: SpoolStore.remove MOVES the PNG to <session>/removed/; it is never unlinked.
+            replaceSession(try await spool.remove(captureID: id))
+        } catch {
+            setStatus((error as? ShotdeckError)?.errorDescription ?? "Could not remove that capture.")
+        }
+    }
+
+    public func copyCommentedLinks() async {
+        do {
+            let text = try await ledger.clipboardText()
+            let pasteboard = NSPasteboard.general
+            pasteboard.clearContents()
+            pasteboard.setString(text, forType: .string)
+            let count = commentedReturns.count
+            setStatus("Copied \(count) link\(count == 1 ? "" : "s").")
+        } catch {
+            setStatus((error as? ShotdeckError)?.errorDescription ?? "Nothing to copy.")
+        }
+    }
+
+    public func openSpoolFolder() {
+        NSWorkspace.shared.open(paths.spool)
+    }
+
+    public func openScreenRecordingSettings() {
+        guard let url = URL(string:
+            "x-apple.systempreferences:com.apple.preference.security?Privacy_ScreenCapture") else {
+            setStatus("Could not open System Settings.")
+            return
+        }
+        NSWorkspace.shared.open(url)
+    }
+
+    private func persistRegion(_ picked: CaptureRegion) {
+        replaceRegion(picked)
+        if let encoded = try? JSONEncoder().encode(picked) {
+            UserDefaults.standard.set(encoded, forKey: CaptureRegion.defaultsKey)
+        }
+    }
+}
+
+public enum MenuIconState: Equatable {
+    case noRegion, regionEmpty, hasCaptures(Int), capturing, recordingMissing
+
+    public var symbolName: String {
+        switch self {
+        case .noRegion: return "viewfinder"
+        case .regionEmpty: return "viewfinder.rectangular"
+        case .hasCaptures: return "viewfinder.rectangular"
+        case .capturing: return "viewfinder.circle.fill"
+        case .recordingMissing: return "exclamationmark.triangle"
+        }
+    }
+
+    public var countText: String? {
+        if case .hasCaptures(let n) = self { return "\(n)" }
+        return nil
+    }
+}

Sources/Shotdeck/MenuBarView.swift

@@ -0,0 +1,180 @@
+import AppKit
+import SwiftUI
+import ShotdeckCore
+
+struct MenuBarView: View {
+    @Environment(AppModel.self) private var model
+
+    var body: some View {
+        VStack(alignment: .leading, spacing: 8) {
+            statusRow
+            SessionStrip()
+            Divider()
+            actionsList
+            if !model.allReturns.isEmpty {
+                Divider()
+                returnsBlock
+            }
+        }
+        .padding(10)
+        .frame(width: 320, alignment: .leading)
+        .controlSize(.small)
+    }
+
+    @ViewBuilder
+    private var statusRow: some View {
+        if !model.screenRecordingGranted {
+            HStack(alignment: .top, spacing: 6) {
+                Image(systemName: "exclamationmark.triangle")
+                    .foregroundStyle(.yellow)
+                VStack(alignment: .leading, spacing: 4) {
+                    Text(
+                        ShotdeckError.screenRecordingNotGranted.errorDescription
+                            ?? "Screen Recording is turned off."
+                    )
+                    .font(.caption)
+                    .fixedSize(horizontal: false, vertical: true)
+                    Button("Open Screen Recording settings") {
+                        model.openScreenRecordingSettings()
+                    }
+                }
+            }
+        } else {
+            Text(model.statusLine ?? defaultStatusText)
+                .font(.caption)
+                .foregroundStyle(.primary)
+                .fixedSize(horizontal: false, vertical: true)
+        }
+    }
+
+    private var defaultStatusText: String {
+        guard let region = model.region else {
+            return "No region yet — press ⌥⇧2 to pick one."
+        }
+        let w = Int(region.rect.width)
+        let h = Int(region.rect.height)
+        let display = displayName(for: region)
+        if model.session.isEmpty {
+            return "Region \(w) × \(h) on \(display) · Nothing captured yet."
+        }
+        let count = model.session.captures.count
+        return "\(count) captures · region \(w) × \(h) on \(display)"
+    }
+
+    private func displayName(for region: CaptureRegion) -> String {
+        for (index, screen) in NSScreen.screens.enumerated() {
+            let id = (screen.deviceDescription[NSDeviceDescriptionKey("NSScreenNumber")] as? NSNumber)?
+                .uint32Value
+            if id == region.displayID {
+                return "Display \(index + 1)"
+            }
+        }
+        return "Display 1"
+    }
+
+    private var actionsList: some View {
+        VStack(alignment: .leading, spacing: 2) {
+            Button {
+                let anchor = NSApp.keyWindow?.contentView
+                if let sender = model as? SendCapable {
+                    Task { await sender.send(anchor: anchor) }
+                } else {
+                    model.setStatus("Send is not available in this build.")
+                }
+            } label: {
+                actionLabel("Send…")
+            }
+            .disabled(model.session.isEmpty || model.isSending)
+
+            Button {
+                Task { await model.captureNow() }
+            } label: {
+                actionLabel("Capture now", trailing: "⌥⇧2")
+            }
+            .disabled(model.isCapturing)
+
+            Button {
+                Task { await model.rePickRegion() }
+            } label: {
+                actionLabel("Re-select area")
+            }
+
+            Button {
+                Task { await model.copyCommentedLinks() }
+            } label: {
+                actionLabel(
+                    "Copy commented links",
+                    trailing: model.commentedReturns.isEmpty ? nil : "\(model.commentedReturns.count)"
+                )
+            }
+            .disabled(model.commentedReturns.isEmpty)
+
+            Button {
+                model.openSpoolFolder()
+            } label: {
+                actionLabel("Open spool folder")
+            }
+
+            Button {
+                if let presenter = model as? SettingsWindowPresenting {
+                    presenter.presentSettingsWindow()
+                } else {
+                    model.setStatus("Settings is not available in this build.")
+                }
+            } label: {
+                actionLabel("Settings…")
+            }
+
+            Button {
+                NSApp.terminate(nil)
+            } label: {
+                actionLabel("Quit Shotdeck")
+            }
+        }
+        .buttonStyle(.plain)
+    }
+
+    private func actionLabel(_ title: String, trailing: String? = nil) -> some View {
+        HStack(spacing: 8) {
+            Text(title)
+            Spacer(minLength: 8)
+            if let trailing {
+                Text(trailing)
+                    .foregroundStyle(.secondary)
+                    .monospacedDigit()
+            }
+        }
+        .frame(maxWidth: .infinity, alignment: .leading)
+        .contentShape(Rectangle())
+        .padding(.vertical, 3)
+    }
+
+    @ViewBuilder
+    private var returnsBlock: some View {
+        if let provider = model as? ReturnsSectionProviding {
+            provider.returnsSection()
+        } else {
+            VStack(alignment: .leading, spacing: 4) {
+                Text("Came back from your device")
+                    .font(.caption)
+                    .foregroundStyle(.secondary)
+                ForEach(newestReturns.prefix(8)) { doc in
+                    HStack(spacing: 8) {
+                        Text(doc.fileURL.lastPathComponent)
+                            .lineLimit(1)
+                        Spacer(minLength: 8)
+                        Text(doc.isCommented
+                             ? "\(doc.annotatedPages.count) page\(doc.annotatedPages.count == 1 ? "" : "s") marked"
+                             : "not marked")
+                            .font(.caption)
+                            .foregroundStyle(doc.isCommented ? .primary : .secondary)
+                    }
+                }
+            }
+        }
+    }
+
+    private var newestReturns: [ReturnedDocument] {
+        model.allReturns.sorted { $0.detectedAt > $1.detectedAt }
+    }
+}

Sources/Shotdeck/PanelSnapshot.swift

@@ -0,0 +1,295 @@
+import AppKit
+import CoreGraphics
+import Darwin
+import Foundation
+import ImageIO
+import PDFKit
+import SwiftUI
+import ShotdeckCore
+
+/// Headless offscreen renderer for `MenuBarView` / `SettingsView`.
+/// Driven by `SHOTDECK_SNAPSHOT_DIR`; never touches the real Application Support spool.
+enum PanelSnapshot {
+    private static let panelWidth: CGFloat = 340
+
+    /// Called from `main.swift` before `ShotdeckApp.main()`. Returns immediately when the
+    /// env var is unset; otherwise writes the six panel PNGs, prints each path, and `exit`s.
+    @MainActor
+    static func runIfRequested() {
+        guard let raw = ProcessInfo.processInfo.environment["SHOTDECK_SNAPSHOT_DIR"],
+              !raw.isEmpty
+        else { return }
+
+        let app = NSApplication.shared
+        app.setActivationPolicy(.prohibited)
+
+        Task { @MainActor in
+            do {
+                try await captureAll(to: URL(fileURLWithPath: raw, isDirectory: true))
+                exit(0)
+            } catch {
+                fputs("PanelSnapshot failed: \(error)\n", stderr)
+                exit(1)
+            }
+        }
+
+        app.run()
+        exit(0)
+    }
+
+    @MainActor
+    private static func captureAll(to directory: URL) async throws {
+        try FileManager.default.createDirectory(at: directory, withIntermediateDirectories: true)
+
+        let (model, root) = try makeIsolatedModel()
+        defer { try? FileManager.default.removeItem(at: root) }
+
+        let region = sampleRegion()
+
+        // 01 — Screen Recording missing (no public mutator; snapshot-only seam).
+        model.snapshotSetScreenRecordingGranted(false)
+        model.replaceRegion(nil)
+        try renderMenuBar(model: model, to: directory, name: "01-no-permission")
+
+        // 02 — granted, no region picked.
+        model.snapshotSetScreenRecordingGranted(true)
+        model.replaceRegion(nil)
+        try renderMenuBar(model: model, to: directory, name: "02-no-region")
+
+        // 03 — region set, empty session.
+        model.replaceRegion(region)
+        try renderMenuBar(model: model, to: directory, name: "03-empty-session")
+
+        // 04 — three real PNGs in the temp spool so SessionStrip thumbnails decode.
+        let swatches: [(CGFloat, CGFloat, CGFloat)] = [
+            (0.85, 0.22, 0.18),
+            (0.18, 0.62, 0.32),
+            (0.16, 0.38, 0.82),
+        ]
+        for (red, green, blue) in swatches {
+            let png = try makePNGData(width: 192, height: 108, red: red, green: green, blue: blue)
+            _ = try await model.spool.append(
+                pngData: png,
+                pixelWidth: 192,
+                pixelHeight: 108,
+                scale: 2.0,
+                capturedAt: Date()
+            )
+        }
+        model.replaceSession(try await model.spool.currentSession())
+        try renderMenuBar(model: model, to: directory, name: "04-captures-present")
+
+        // 05 — two inspected PDFs in the temp ledger, one marked / one not.
+        try await seedReturns(model: model)
+        try renderMenuBar(model: model, to: directory, name: "05-returns-present")
+
+        // 06 — SettingsView against the same isolated model.
+        try render(
+            SettingsView().environment(model),
+            to: directory.appendingPathComponent("panel-06-settings.png")
+        )
+    }
+
+    @MainActor
+    private static func renderMenuBar(model: AppModel, to directory: URL, name: String) throws {
+        try render(
+            MenuBarView().environment(model),
+            to: directory.appendingPathComponent("panel-\(name).png")
+        )
+    }
+
+    @MainActor
+    private static func render(_ view: some View, to url: URL) throws {
+        let wrapped = view
+            .frame(width: panelWidth, alignment: .topLeading)
+            .fixedSize(horizontal: false, vertical: true)
+            .background(Color(nsColor: .windowBackgroundColor))
+
+        let hosting = NSHostingView(rootView: wrapped)
+        hosting.wantsLayer = true
+        hosting.appearance = NSAppearance(named: .aqua)
+
+        let window = NSWindow(
+            contentRect: NSRect(x: -10_000, y: -10_000, width: panelWidth, height: 64),
+            styleMask: [.borderless],
+            backing: .buffered,
+            defer: false
+        )
+        window.isReleasedWhenClosed = false
+        window.appearance = NSAppearance(named: .aqua)
+        window.backgroundColor = .windowBackgroundColor
+        window.isOpaque = true
+        window.alphaValue = 0
+        window.contentView = hosting
+        window.orderBack(nil)
+
+        hosting.layoutSubtreeIfNeeded()
+        var size = hosting.fittingSize
+        if size.height < 1 {
+            size.height = hosting.intrinsicContentSize.height
+        }
+        if size.height < 1 { size.height = 240 }
+        size.width = panelWidth
+        size.height = ceil(size.height)
+
+        hosting.setFrameSize(size)
+        window.setContentSize(size)
+        hosting.layoutSubtreeIfNeeded()
+        RunLoop.current.run(until: Date(timeIntervalSinceNow: 0.05))
+
+        let bounds = hosting.bounds
+        guard let rep = hosting.bitmapImageRepForCachingDisplay(in: bounds) else {
+            throw SnapshotError.renderFailed(url.lastPathComponent)
+        }
+        hosting.cacheDisplay(in: bounds, to: rep)
+        guard let png = rep.representation(using: .png, properties: [:]) else {
+            throw SnapshotError.encodeFailed(url.lastPathComponent)
+        }
+        try png.write(to: url)
+        print(url.path)
+        fflush(stdout)
+
+        window.contentView = nil
+        window.close()
+    }
+
+    @MainActor
+    private static func makeIsolatedModel() throws -> (model: AppModel, root: URL) {
+        let root = FileManager.default.temporaryDirectory
+            .appendingPathComponent("shotdeck-panel-snapshot-\(UUID().uuidString)", isDirectory: true)
+        let paths = try AppSupportPaths(
+            root: root,
+            outbox: root.appendingPathComponent("outbox", isDirectory: true),
+            watchFolder: root.appendingPathComponent("watch", isDirectory: true)
+        )
+        let ledger = try ReturnLedger(paths: paths)
+        let model = AppModel(
+            paths: paths,
+            spool: try SpoolStore(paths: paths),
+            composer: PDFComposer(),
+            capturer: ScreenCapturer(),
+            hotkeys: HotkeyCenter(),
+            picker: RegionPickerController(),
+            ledger: ledger,
+            watcher: ReturnWatcher(paths: paths, ledger: ledger)
+        )
+        model.setFolderURLs(outbox: paths.outbox, watch: paths.watchFolder)
+        return (model, root)
+    }
+
+    @MainActor
+    private static func seedReturns(model: AppModel) async throws {
+        let watch = model.paths.watchFolder
+        let unmarkedURL = watch.appendingPathComponent("Shotdeck-20260901-120000.pdf")
+        let markedURL = watch.appendingPathComponent("Shotdeck-20260901-120100.pdf")
+        try writeShotdeckPDF(to: unmarkedURL, marked: false)
+        try writeShotdeckPDF(to: markedURL, marked: true)
+
+        let unmarked = try AnnotationInspector.inspect(fileURL: unmarkedURL)
+        let marked = try AnnotationInspector.inspect(fileURL: markedURL)
+        try await model.ledger.record(unmarked)
+        try await model.ledger.record(marked)
+        model.setReturns(
+            all: try await model.ledger.all(),
+            commented: try await model.ledger.commented()
+        )
+    }
+
+    private static func sampleRegion() -> CaptureRegion {
+        CaptureRegion(
+            displayID: CGMainDisplayID(),
+            rect: CGRect(x: 120, y: 80, width: 800, height: 600),
+            capturedScale: 2.0
+        )
+    }
+
+    private static func makePNGData(
+        width: Int,
+        height: Int,
+        red: CGFloat,
+        green: CGFloat,
+        blue: CGFloat
+    ) throws -> Data {
+        let colorSpace = CGColorSpaceCreateDeviceRGB()
+        guard let context = CGContext(
+            data: nil,
+            width: width,
+            height: height,
+            bitsPerComponent: 8,
+            bytesPerRow: width * 4,
+            space: colorSpace,
+            bitmapInfo: CGImageAlphaInfo.premultipliedLast.rawValue
+        ) else {
+            throw SnapshotError.pngGenerationFailed
+        }
+        context.setFillColor(red: red, green: green, blue: blue, alpha: 1)
+        context.fill(CGRect(x: 0, y: 0, width: width, height: height))
+        guard let image = context.makeImage() else {
+            throw SnapshotError.pngGenerationFailed
+        }
+        let buffer = NSMutableData()
+        guard let destination = CGImageDestinationCreateWithData(
+            buffer,
+            "public.png" as CFString,
+            1,
+            nil
+        ) else {
+            throw SnapshotError.pngGenerationFailed
+        }
+        CGImageDestinationAddImage(destination, image, nil)
+        guard CGImageDestinationFinalize(destination) else {
+            throw SnapshotError.pngGenerationFailed
+        }
+        return buffer as Data
+    }
+
+    private static func writeShotdeckPDF(to url: URL, marked: Bool) throws {
+        let document = PDFDocument()
+        let page = PDFPage()
+        page.setBounds(CGRect(x: 0, y: 0, width: 612, height: 792), for: .mediaBox)
+        document.insert(page, at: 0)
+        document.documentAttributes = [
+            PDFDocumentAttribute.creatorAttribute: "Shotdeck",
+            PDFDocumentAttribute.subjectAttribute: UUID().uuidString,
+        ]
+        if marked {
+            let annotation = PDFAnnotation(
+                bounds: CGRect(x: 72, y: 400, width: 220, height: 36),
+                forType: .highlight,
+                withProperties: nil
+            )
+            page.addAnnotation(annotation)
+        }
+        guard document.write(to: url) else {
+            throw SnapshotError.pdfWriteFailed(url.lastPathComponent)
+        }
+    }
+}
+
+extension AppModel {
+    /// `screenRecordingGranted` is `public private(set)` with no seam mutator.
+    /// Snapshot-only: the KeyPath setter exists at runtime; compile-time access is file-private.
+    func snapshotSetScreenRecordingGranted(_ granted: Bool) {
+        // private(set) types this as KeyPath; the setter still exists on the @Observable storage.
+        let writable: ReferenceWritableKeyPath<AppModel, Bool> = unsafeBitCast(
+            \AppModel.screenRecordingGranted, to: ReferenceWritableKeyPath<AppModel, Bool>.self
+        )
+        self[keyPath: writable] = granted
+    }
+}
+
+private enum SnapshotError: Error, CustomStringConvertible {
+    case renderFailed(String)
+    case encodeFailed(String)
+    case pngGenerationFailed
+    case pdfWriteFailed(String)
+
+    var description: String {
+        switch self {
+        case .renderFailed(let name): return "bitmapImageRepForCachingDisplay failed for \(name)"
+        case .encodeFailed(let name): return "PNG encode failed for \(name)"
+        case .pngGenerationFailed: return "CoreGraphics PNG generation failed"
+        case .pdfWriteFailed(let name): return "could not write \(name)"
+        }
+    }
+}

Sources/Shotdeck/RegionPickerController.swift

@@ -0,0 +1,181 @@
+import AppKit
+import ShotdeckCore
+
+@MainActor
+public final class RegionPickerController {
+    private var windows: [RegionPickerWindow] = []
+    private var monitor: Any?
+    private var completion: (@MainActor (CaptureRegion?) -> Void)?
+    private var dragStart: NSPoint?
+    private var startScreen: NSScreen?
+    private var cursorPushed = false
+
+    public init() {}
+
+    /// Presents one overlay per attached screen. A pick already in progress is cancelled
+    /// (its completion called with nil) before the new one starts — never leaves a caller
+    /// waiting forever on a dropped re-entrant call.
+    public func pick(completion: @escaping @MainActor (CaptureRegion?) -> Void) {
+        if self.completion != nil {
+            finish(region: nil)
+        }
+        self.completion = completion
+        presentOverlays()
+    }
+
+    private func presentOverlays() {
+        let screens = NSScreen.screens
+        guard !screens.isEmpty else {
+            finish(region: nil)
+            return
+        }
+
+        NSCursor.crosshair.push()
+        cursorPushed = true
+
+        windows = screens.map { RegionPickerWindow(screen: $0) }
+        for window in windows {
+            window.orderFrontRegardless()
+        }
+        // Nonactivating panel can become key without activating the app; needed so
+        // Escape reaches the local monitor immediately, before any mouse click.
+        let mouse = NSEvent.mouseLocation
+        let keyWindow = windows.first(where: { $0.coveringScreen.frame.contains(mouse) })
+            ?? windows[0]
+        keyWindow.makeKey()
+
+        monitor = NSEvent.addLocalMonitorForEvents(
+            matching: [.leftMouseDown, .leftMouseDragged, .leftMouseUp, .keyDown]
+        ) { [weak self] event in
+            guard let self else { return event }
+            // NSEvent is not Sendable; lift the two Sendable fields the handler
+            // needs. Mouse geometry is read from NSEvent.mouseLocation on the
+            // main thread inside the isolated methods, per spec.
+            let type = event.type
+            let keyCode = event.keyCode
+            let consume = MainActor.assumeIsolated {
+                self.handle(type: type, keyCode: keyCode)
+            }
+            return consume ? nil : event
+        }
+    }
+
+    /// Returns `true` when the event should be swallowed.
+    private func handle(type: NSEvent.EventType, keyCode: UInt16) -> Bool {
+        switch type {
+        case .keyDown:
+            if keyCode == 53 { // kVK_Escape
+                finish(region: nil)
+                return true
+            }
+            return false
+        case .leftMouseDown:
+            handleMouseDown()
+            return false
+        case .leftMouseDragged:
+            handleMouseDragged()
+            return false
+        case .leftMouseUp:
+            handleMouseUp()
+            return false
+        default:
+            return false
+        }
+    }
+
+    private func handleMouseDown() {
+        let point = NSEvent.mouseLocation
+        dragStart = point
+        startScreen = NSScreen.screens.first(where: { $0.frame.contains(point) })
+            ?? NSScreen.screens.first
+        guard let startScreen else { return }
+        let local = Self.localRect(
+            from: CGRect(origin: point, size: .zero).intersection(startScreen.frame),
+            on: startScreen
+        )
+        window(for: startScreen)?.updateSelection(localRect: local, sizeText: "0 x 0")
+        for window in windows where window.coveringScreen !== startScreen {
+            window.updateSelection(localRect: nil, sizeText: nil)
+        }
+    }
+
+    private func handleMouseDragged() {
+        guard dragStart != nil, startScreen != nil else { return }
+        applyLiveSelection()
+    }
+
+    private func handleMouseUp() {
+        guard let startScreen else {
+            dragStart = nil
+            return
+        }
+        guard let rect = currentClampedRect(), rect.width >= 8, rect.height >= 8 else {
+            // Mis-click: reset drag state, leave every window open and fully dimmed.
+            dragStart = nil
+            self.startScreen = nil
+            for window in windows {
+                window.updateSelection(localRect: nil, sizeText: nil)
+            }
+            return
+        }
+        let region = CaptureRegion.fromAppKit(rect: rect, on: startScreen)
+        finish(region: region)
+    }
+
+    private func applyLiveSelection() {
+        guard let startScreen, let rect = currentClampedRect() else { return }
+        let local = Self.localRect(from: rect, on: startScreen)
+        let text = "\(Int(rect.width)) x \(Int(rect.height))"
+        window(for: startScreen)?.updateSelection(localRect: local, sizeText: text)
+        for window in windows where window.coveringScreen !== startScreen {
+            window.updateSelection(localRect: nil, sizeText: nil)
+        }
+    }
+
+    /// Normalize the drag (so bottom-right → up-left is not misjudged) then clamp
+    /// to the screen the gesture started on — never selects across displays.
+    private func currentClampedRect() -> CGRect? {
+        guard let dragStart, let startScreen else { return nil }
+        let current = NSEvent.mouseLocation
+        let normalized = CGRect(
+            x: min(dragStart.x, current.x),
+            y: min(dragStart.y, current.y),
+            width: abs(current.x - dragStart.x),
+            height: abs(current.y - dragStart.y)
+        )
+        return normalized.intersection(startScreen.frame)
+    }
+
+    private func window(for screen: NSScreen) -> RegionPickerWindow? {
+        windows.first { $0.coveringScreen === screen }
+    }
+
+    private static func localRect(from rect: CGRect, on screen: NSScreen) -> CGRect {
+        CGRect(
+            x: rect.minX - screen.frame.minX,
+            y: rect.minY - screen.frame.minY,
+            width: rect.width,
+            height: rect.height
+        )
+    }
+
+    private func finish(region: CaptureRegion?) {
+        if let monitor {
+            NSEvent.removeMonitor(monitor)
+            self.monitor = nil
+        }
+        if cursorPushed {
+            NSCursor.pop()
+            cursorPushed = false
+        }
+        for window in windows {
+            window.orderOut(nil)
+        }
+        windows.removeAll()
+        dragStart = nil
+        startScreen = nil
+        let done = completion
+        completion = nil
+        done?(region)
+    }
+}

Sources/Shotdeck/RegionPickerWindow.swift

@@ -0,0 +1,110 @@
+import AppKit
+
+/// Full-screen dim overlay for one attached display. Subclasses `NSPanel` with
+/// `.nonactivatingPanel` so it can accept mouse and key events without activating
+/// Shotdeck or stealing the frontmost app beyond those events.
+@MainActor
+final class RegionPickerWindow: NSPanel {
+    let coveringScreen: NSScreen
+    private let pickerView: RegionPickerView
+
+    init(screen: NSScreen) {
+        self.coveringScreen = screen
+        self.pickerView = RegionPickerView(frame: CGRect(origin: .zero, size: screen.frame.size))
+        super.init(
+            contentRect: screen.frame,
+            styleMask: [.borderless, .nonactivatingPanel],
+            backing: .buffered,
+            defer: false
+        )
+        setFrame(screen.frame, display: false)
+        level = .screenSaver
+        isOpaque = false
+        backgroundColor = .clear
+        ignoresMouseEvents = false
+        hasShadow = false
+        isMovable = false
+        hidesOnDeactivate = false
+        isFloatingPanel = true
+        becomesKeyOnlyIfNeeded = false
+        animationBehavior = .none
+        collectionBehavior = [.canJoinAllSpaces, .fullScreenAuxiliary, .stationary]
+        contentView = pickerView
+    }
+
+    override var canBecomeKey: Bool { true }
+    override var canBecomeMain: Bool { false }
+
+    /// `localRect` is in this window's coordinates (screen.frame origin subtracted).
+    /// Pass `nil` to restore the full dim with no punch and no size chip.
+    func updateSelection(localRect: CGRect?, sizeText: String?) {
+        pickerView.selectionLocalRect = localRect
+        pickerView.sizeChipText = sizeText
+        pickerView.needsDisplay = true
+    }
+}
+
+/// Draws ~35% black over the screen with an even-odd punch for the live selection,
+/// a thin light border, and the size-readout chip.
+@MainActor
+private final class RegionPickerView: NSView {
+    var selectionLocalRect: CGRect?
+    var sizeChipText: String?
+
+    override var isOpaque: Bool { false }
+    override var acceptsFirstResponder: Bool { true }
+
+    override func draw(_ dirtyRect: NSRect) {
+        super.draw(dirtyRect)
+
+        let dim = NSColor.black.withAlphaComponent(0.35)
+        let path = NSBezierPath(rect: bounds)
+        if let sel = selectionLocalRect, sel.width > 0, sel.height > 0 {
+            path.append(NSBezierPath(rect: sel))
+            path.windingRule = .evenOdd
+        }
+        dim.setFill()
+        path.fill()
+
+        guard let sel = selectionLocalRect, sel.width > 0, sel.height > 0 else { return }
+
+        NSColor.white.withAlphaComponent(0.85).setStroke()
+        let border = NSBezierPath(rect: sel)
+        border.lineWidth = 1
+        border.stroke()
+
+        if let text = sizeChipText {
+            drawSizeChip(text, above: sel)
+        }
+    }
+
+    private func drawSizeChip(_ text: String, above sel: CGRect) {
+        let attrs: [NSAttributedString.Key: Any] = [
+            .font: NSFont.systemFont(ofSize: NSFont.smallSystemFontSize),
+            .foregroundColor: NSColor.white,
+        ]
+        let nsText = text as NSString
+        let textSize = nsText.size(withAttributes: attrs)
+        let padX: CGFloat = 8
+        let padY: CGFloat = 4
+        let chipSize = CGSize(
+            width: ceil(textSize.width) + padX * 2,
+            height: ceil(textSize.height) + padY * 2
+        )
+
+        var origin = CGPoint(x: sel.minX, y: sel.maxY + 6)
+        if origin.y + chipSize.height > bounds.maxY {
+            origin.y = sel.minY - 6 - chipSize.height
+        }
+        origin.x = min(max(origin.x, bounds.minX + 4), bounds.maxX - chipSize.width - 4)
+        origin.y = min(max(origin.y, bounds.minY + 4), bounds.maxY - chipSize.height - 4)
+
+        let chipRect = CGRect(origin: origin, size: chipSize)
+        NSColor.black.withAlphaComponent(0.75).setFill()
+        NSBezierPath(roundedRect: chipRect, xRadius: 4, yRadius: 4).fill()
+        nsText.draw(
+            at: CGPoint(x: chipRect.minX + padX, y: chipRect.minY + padY),
+            withAttributes: attrs
+        )
+    }
+}

Sources/Shotdeck/ReturnsList.swift

@@ -0,0 +1,53 @@
+import AppKit
+import SwiftUI
+import ShotdeckCore
+
+func newestReturnsForDisplay(_ returns: [ReturnedDocument], limit: Int = 8) -> [ReturnedDocument] {
+    Array(returns.sorted { $0.detectedAt > $1.detectedAt }.prefix(limit))
+}
+
+func returnMarkLabel(_ document: ReturnedDocument) -> String {
+    guard document.isCommented else { return "not marked" }
+    let count = document.annotatedPages.count
+    return "\(count) page\(count == 1 ? "" : "s") marked"
+}
+
+struct ReturnsList: View {
+    let returns: [ReturnedDocument]
+
+    var body: some View {
+        let visible = newestReturnsForDisplay(returns)
+        if visible.isEmpty {
+            EmptyView()
+        } else {
+            VStack(alignment: .leading, spacing: 4) {
+                Text("Came back from your device")
+                    .font(.caption)
+                    .foregroundStyle(.secondary)
+                ForEach(visible) { document in
+                    Button {
+                        NSWorkspace.shared.activateFileViewerSelecting([document.fileURL])
+                    } label: {
+                        HStack(spacing: 8) {
+                            Text(document.fileURL.lastPathComponent)
+                                .lineLimit(1)
+                            Spacer(minLength: 8)
+                            Text(returnMarkLabel(document))
+                                .font(.caption)
+                                .foregroundStyle(document.isCommented ? .primary : .secondary)
+                        }
+                    }
+                    .buttonStyle(.plain)
+                    .help(DubaiTime.stamp(document.detectedAt))
+                }
+            }
+        }
+    }
+}
+
+extension AppModel: ReturnsSectionProviding {
+    public func returnsSection() -> AnyView {
+        guard !allReturns.isEmpty else { return AnyView(EmptyView()) }
+        return AnyView(ReturnsList(returns: allReturns))
+    }
+}

Sources/Shotdeck/SendController.swift

@@ -0,0 +1,71 @@
+import AppKit
+import Darwin
+import Foundation
+import ShotdeckCore
+
+extension AppModel: SendCapable {
+    public func send(anchor: NSView?) async {
+        guard !session.isEmpty, !isSending else { return }
+        setSending(true)
+        defer { setSending(false) }
+
+        let workingSession = session
+        let composer = self.composer
+        // Live outbox (FolderSettings), not `paths.outbox` — Settings changes take effect.
+        let outboxDir = outboxURL
+        let sourceDir = paths.sessionDirectory(workingSession.id)
+        let fileName = PDFComposer.fileName(for: workingSession)
+        let finalURL = outboxDir.appendingPathComponent(fileName)
+        // Same directory as the final target so the rename below is same-volume (atomic).
+        let tempURL = outboxDir.appendingPathComponent(".shotdeck-\(UUID().uuidString).pdf")
+        let title = "Shotdeck – \(DubaiTime.stamp(workingSession.createdAt))"
+
+        do {
+            // D-13: build off the main actor. Only Sendable values cross into the
+            // detached task — never `anchor` (NSView is not Sendable).
+            try await Task.detached(priority: .userInitiated) {
+                _ = try composer.compose(
+                    session: workingSession,
+                    imageURL: { capture in sourceDir.appendingPathComponent(capture.fileName) },
+                    title: title,
+                    to: tempURL
+                )
+                // POSIX rename onto `finalURL` replaces any same-name file in one
+                // directory operation; there is never a window where the PDF is gone.
+                if Darwin.rename(tempURL.path, finalURL.path) != 0 {
+                    throw ShotdeckError.pdfCompositionFailed(
+                        reason: "could not publish the PDF: \(String(cString: strerror(errno)))"
+                    )
+                }
+                try AtomicFile.fsyncDirectory(at: outboxDir)
+            }.value
+
+            // File exists on disk now — archive only after that (D-13). A later AirDrop
+            // failure never deletes this file.
+            guard FileManager.default.fileExists(atPath: finalURL.path) else {
+                throw ShotdeckError.pdfCompositionFailed(reason: "the PDF was not written to disk")
+            }
+            _ = try await spool.archiveCurrent(pdfFileName: fileName)
+            replaceSession(try await spool.currentSession())
+
+            let pageWord = workingSession.captures.count == 1 ? "page" : "pages"
+            setStatus("Sent — \(workingSession.captures.count) \(pageWord).")
+
+            guard let anchor else {
+                setStatus("PDF saved to \(outboxDisplayName). Open the panel to AirDrop it.")
+                return
+            }
+            do {
+                try Sharing.airDrop(fileURL: finalURL, from: anchor)
+            } catch {
+                setStatus(
+                    "AirDrop is not available right now — the PDF is on your \(outboxDisplayName)."
+                )
+            }
+        } catch {
+            // Never unlink the published PDF, and never unlink `tempURL` either:
+            // a rename failure would leave the complete document at the temp name.
+            setStatus((error as? ShotdeckError)?.errorDescription ?? "The PDF could not be built.")
+        }
+    }
+}

Sources/Shotdeck/SessionStrip.swift

@@ -0,0 +1,78 @@
+import AppKit
+import SwiftUI
+import ShotdeckCore
+
+struct SessionStrip: View {
+    @Environment(AppModel.self) private var model
+
+    var body: some View {
+        if model.session.captures.isEmpty {
+            Text("Nothing captured yet.")
+                .font(.caption)
+                .foregroundStyle(.secondary)
+                .frame(maxWidth: .infinity, minHeight: 64, alignment: .leading)
+        } else {
+            ScrollView(.horizontal, showsIndicators: false) {
+                HStack(alignment: .top, spacing: 6) {
+                    ForEach(model.session.captures) { capture in
+                        SessionThumb(capture: capture)
+                    }
+                }
+            }
+            .frame(height: 64)
+        }
+    }
+}
+
+private struct SessionThumb: View {
+    @Environment(AppModel.self) private var model
+    let capture: Capture
+    @State private var hovering = false
+
+    var body: some View {
+        ZStack(alignment: .topLeading) {
+            thumbnail
+            Text("\(capture.sequence)")
+                .font(.system(size: 9, weight: .bold))
+                .foregroundStyle(.white)
+                .padding(.horizontal, 4)
+                .padding(.vertical, 1)
+                .background(.black.opacity(0.65))
+                .clipShape(RoundedRectangle(cornerRadius: 2, style: .continuous))
+                .padding(3)
+            if hovering {
+                VStack {
+                    Spacer()
+                    Button("Remove") {
+                        Task { await model.removeCapture(id: capture.id) }
+                    }
+                    .font(.system(size: 10, weight: .semibold))
+                    .buttonStyle(.plain)
+                    .foregroundStyle(.white)
+                    .frame(maxWidth: .infinity)
+                    .padding(.vertical, 3)
+                    .background(.black.opacity(0.7))
+                }
+            }
+        }
+        .frame(height: 64)
+        .clipped()
+        .onHover { hovering = $0 }
+        .help(DubaiTime.stamp(capture.capturedAt))
+    }
+
+    @ViewBuilder
+    private var thumbnail: some View {
+        let url = model.paths.sessionDirectory(model.session.id).appendingPathComponent(capture.fileName)
+        if let image = NSImage(contentsOf: url) {
+            Image(nsImage: image)
+                .resizable()
+                .aspectRatio(contentMode: .fit)
+                .frame(height: 64)
+        } else {
+            Rectangle()
+                .fill(Color.secondary.opacity(0.2))
+                .frame(width: 64, height: 64)
+        }
+    }
+}

Sources/Shotdeck/SettingsView.swift

@@ -0,0 +1,138 @@
+import AppKit
+import SwiftUI
+import ShotdeckCore
+
+struct SettingsView: View {
+    @Environment(AppModel.self) private var model
+
+    private let labelWidth: CGFloat = 104
+
+    var body: some View {
+        Grid(alignment: .leading, horizontalSpacing: 12, verticalSpacing: 10) {
+            GridRow {
+                Text("Hotkey")
+                    .font(.headline)
+                    .frame(maxWidth: .infinity, alignment: .leading)
+                    .gridCellColumns(2)
+            }
+
+            GridRow(alignment: .firstTextBaseline) {
+                fieldLabel("Capture")
+                Text("⌥⇧2 — fixed in this version")
+                    .foregroundStyle(.secondary)
+                    .lineLimit(1)
+                    .frame(maxWidth: .infinity, alignment: .leading)
+                    .frame(minHeight: 22, alignment: .leading)
+            }
+
+            GridRow {
+                Text("Folders")
+                    .font(.headline)
+                    .frame(maxWidth: .infinity, alignment: .leading)
+                    .gridCellColumns(2)
+                    .padding(.top, 6)
+            }
+
+            GridRow(alignment: .center) {
+                fieldLabel("Watch folder")
+                folderValue(path: model.watchFolderURL.path) {
+                    model.chooseWatchFolder()
+                }
+            }
+
+            GridRow(alignment: .center) {
+                fieldLabel("Output folder")
+                folderValue(path: model.outboxURL.path) {
+                    model.chooseOutboxFolder()
+                }
+            }
+
+            GridRow {
+                Button("Reveal spool folder") { model.openSpoolFolder() }
+                    .gridCellColumns(2)
+                    .frame(maxWidth: .infinity, alignment: .leading)
+                    .padding(.top, 4)
+            }
+        }
+        .padding(16)
+        .frame(minWidth: 320, idealWidth: 360, maxWidth: 360, alignment: .leading)
+        .controlSize(.small)
+    }
+
+    private func fieldLabel(_ title: String) -> some View {
+        Text(title)
+            .lineLimit(1)
+            .frame(width: labelWidth, alignment: .trailing)
+            .gridColumnAlignment(.trailing)
+            .frame(minHeight: 22, alignment: .trailing)
+    }
+
+    private func folderValue(path: String, choose: @escaping () -> Void) -> some View {
+        HStack(spacing: 8) {
+            Text(path)
+                .lineLimit(1)
+                .truncationMode(.middle)
+                .foregroundStyle(.secondary)
+                .frame(maxWidth: .infinity, alignment: .leading)
+            Button("Choose…") { choose() }
+        }
+        .frame(minHeight: 22)
+    }
+}
+
+extension AppModel: SettingsWindowPresenting {
+    private static var settingsWindowController: NSWindowController?
+
+    public func presentSettingsWindow() {
+        if let existing = Self.settingsWindowController {
+            existing.window?.makeKeyAndOrderFront(nil)
+            NSApp.activate()
+            return
+        }
+        let hosting = NSHostingController(rootView: SettingsView().environment(self))
+        let window = NSWindow(contentViewController: hosting)
+        window.title = "Shotdeck Settings"
+        window.styleMask = [.titled, .closable]
+        window.isReleasedWhenClosed = false
+        window.center()
+        let controller = NSWindowController(window: window)
+        Self.settingsWindowController = controller
+        controller.showWindow(nil)
+        NSApp.activate()
+    }
+
+    func chooseOutboxFolder() {
+        guard let url = chooseDirectory(startingAt: outboxURL) else { return }
+        FolderSettings.setOutbox(url)
+        setFolderURLs(outbox: url, watch: watchFolderURL)
+        setStatus("Output folder set to \(url.lastPathComponent).")
+    }
+
+    func chooseWatchFolder() {
+        guard let url = chooseDirectory(startingAt: watchFolderURL) else { return }
+        FolderSettings.setWatchFolder(url)
+        setFolderURLs(outbox: outboxURL, watch: url)
+        Task {
+            do {
+                try await watcher.updateWatchFolder(url)
+                setStatus("Watch folder set to \(url.lastPathComponent).")
+            } catch {
+                setStatus(
+                    (error as? ShotdeckError)?.errorDescription ?? "Could not switch the watch folder."
+                )
+            }
+        }
+    }
+
+    private func chooseDirectory(startingAt directory: URL) -> URL? {
+        let panel = NSOpenPanel()
+        panel.canChooseDirectories = true
+        panel.canChooseFiles = false
+        panel.allowsMultipleSelection = false
+        panel.canCreateDirectories = true
+        panel.prompt = "Choose"
+        panel.directoryURL = directory
+        guard panel.runModal() == .OK else { return nil }
+        return panel.url
+    }
+}

Sources/Shotdeck/Sharing.swift

@@ -0,0 +1,83 @@
+import AppKit
+import ShotdeckCore
+
+@MainActor
+enum Sharing {
+    /// Presents the AirDrop picker for `fileURL`, anchored to `view`.
+    /// Throws `ShotdeckError.airDropUnavailable` when the service cannot be created,
+    /// `canPerform` is false, or `view` is not in a visible window (a detached view
+    /// never produces an on-screen sheet).
+    static func airDrop(fileURL: URL, from view: NSView) throws {
+        guard let service = NSSharingService(named: .sendViaAirDrop),
+              service.canPerform(withItems: [fileURL]) else {
+            throw ShotdeckError.airDropUnavailable
+        }
+        // Presenting from a detached NSView (no window) yields a sheet that never appears.
+        guard let window = view.window, window.isVisible else {
+            throw ShotdeckError.airDropUnavailable
+        }
+
+        NSApp.activate()
+        window.makeKeyAndOrderFront(nil)
+
+        service.subject = fileURL.lastPathComponent
+        let session = AirDropSession(service: service, window: window, view: view)
+        AirDropSession.keepAlive(session)
+        service.delegate = session
+        service.perform(withItems: [fileURL])
+    }
+}
+
+/// Retains the sharing service for the life of the picker and supplies the real
+/// on-screen window as the sheet parent. `NSSharingService.delegate` is weak.
+@MainActor
+private final class AirDropSession: NSObject, NSSharingServiceDelegate {
+    static var live: [AirDropSession] = []
+
+    let service: NSSharingService
+    let window: NSWindow
+    let view: NSView
+
+    init(service: NSSharingService, window: NSWindow, view: NSView) {
+        self.service = service
+        self.window = window
+        self.view = view
+    }
+
+    static func keepAlive(_ session: AirDropSession) {
+        live.append(session)
+    }
+
+    private func drop() {
+        Self.live.removeAll { $0 === self }
+    }
+
+    func sharingService(
+        _ sharingService: NSSharingService,
+        sourceWindowForShareItems items: [Any],
+        sharingContentScope: UnsafeMutablePointer<NSSharingService.SharingContentScope>
+    ) -> NSWindow? {
+        sharingContentScope.pointee = .item
+        return window
+    }
+
+    func sharingService(
+        _ sharingService: NSSharingService,
+        sourceFrameOnScreenForShareItem item: Any
+    ) -> NSRect {
+        let inWindow = view.convert(view.bounds, to: nil)
+        return window.convertToScreen(inWindow)
+    }
+
+    func sharingService(_ sharingService: NSSharingService, didShareItems items: [Any]) {
+        drop()
+    }
+
+    func sharingService(
+        _ sharingService: NSSharingService,
+        didFailToShareItems items: [Any],
+        error: any Error
+    ) {
+        drop()
+    }
+}

Sources/Shotdeck/main.swift

@@ -1,6 +1,78 @@
 import AppKit
+import SwiftUI
+import ShotdeckCore
 
-// WP-4 replaces this body with the real menu-bar UI.
-let application = NSApplication.shared
-application.setActivationPolicy(.accessory)
-application.run()
+// SwiftPM treats a file named main.swift as top-level code, which forbids `@main`.
+// App.main() is the equivalent entry point.
+if ProcessInfo.processInfo.environment["SHOTDECK_SNAPSHOT_DIR"] != nil {
+    MainActor.assumeIsolated { PanelSnapshot.runIfRequested() }
+}
+ShotdeckApp.main()
+
+struct ShotdeckApp: App {
+    @NSApplicationDelegateAdaptor(AppDelegate.self) private var appDelegate
+
+    var body: some Scene {
+        MenuBarExtra {
+            MenuBarView()
+                .environment(appDelegate.model)
+        } label: {
+            let state = appDelegate.model.iconState
+            HStack(spacing: 4) {
+                Image(systemName: state.symbolName)
+                if let count = state.countText {
+                    Text(count).font(.system(size: 11, weight: .semibold))
+                }
+            }
+            .accessibilityLabel("Shotdeck")
+        }
+        .menuBarExtraStyle(.window)
+    }
+}
+
+@MainActor
+final class AppDelegate: NSObject, NSApplicationDelegate {
+    let model: AppModel
+
+    override init() {
+        NSApplication.shared.setActivationPolicy(.accessory)
+        model = AppDelegate.makeLaunchModel()
+        super.init()
+    }
+
+    func applicationDidFinishLaunching(_ notification: Notification) {
+        Task { await model.bootstrap() }
+    }
+
+    private static func makeLaunchModel() -> AppModel {
+        do {
+            let paths = try FolderSettings.resolvedAppSupportPaths()
+            return try makeModel(paths: paths)
+        } catch {
+            Log.ui.critical(
+                "AppModel init failed: \(String(describing: error), privacy: .public)"
+            )
+            let tmp = FileManager.default.temporaryDirectory
+            let fallbackRoot = tmp.appendingPathComponent("Shotdeck-fallback", isDirectory: true)
+            // Safe: temp-dir creation for a path this process controls cannot legitimately fail.
+            let fallback = try! AppSupportPaths(root: fallbackRoot, outbox: tmp, watchFolder: tmp)
+            let model = try! makeModel(paths: fallback)
+            model.setStatus("Shotdeck could not access its storage folder. Captures will not persist.")
+            return model
+        }
+    }
+
+    private static func makeModel(paths: AppSupportPaths) throws -> AppModel {
+        let ledger = try ReturnLedger(paths: paths)
+        return AppModel(
+            paths: paths,
+            spool: try SpoolStore(paths: paths),
+            composer: PDFComposer(),
+            capturer: ScreenCapturer(),
+            hotkeys: HotkeyCenter(),
+            picker: RegionPickerController(),
+            ledger: ledger,
+            watcher: ReturnWatcher(paths: paths, ledger: ledger)
+        )
+    }
+}

Sources/ShotdeckCore/Capture/ScreenCapturer.swift

@@ -0,0 +1,118 @@
+import ScreenCaptureKit
+import CoreGraphics
+import ImageIO
+import UniformTypeIdentifiers
+import AppKit  // NSScreen only, to read backingScaleFactor as a fallback
+import Foundation
+
+public struct CapturedImage: Sendable {
+    public let pngData: Data
+    public let pixelWidth: Int
+    public let pixelHeight: Int
+    public let scale: CGFloat
+}
+
+public struct ScreenCapturer: Sendable {
+    public init() {}
+
+    /// Does NOT prompt. Reports the current Screen Recording grant.
+    public static var isScreenRecordingGranted: Bool { CGPreflightScreenCaptureAccess() }
+
+    /// Captures `region` at the display's true backing scale. Throws
+    /// `.screenRecordingNotGranted` when the grant is absent — never requests it.
+    public func capture(_ region: CaptureRegion) async throws -> CapturedImage {
+        guard Self.isScreenRecordingGranted else {
+            throw ShotdeckError.screenRecordingNotGranted
+        }
+
+        let content: SCShareableContent
+        do {
+            content = try await SCShareableContent.excludingDesktopWindows(
+                false,
+                onScreenWindowsOnly: true
+            )
+        } catch {
+            throw ShotdeckError.captureFailed(underlying: error.localizedDescription)
+        }
+
+        guard let display = content.displays.first(where: { $0.displayID == region.displayID }) else {
+            throw ShotdeckError.displayNoLongerConnected(displayID: region.displayID)
+        }
+
+        // Bounds/clamp: a resolution change often shrinks the display bounds by a few
+        // points without the region Ben picked being meaningfully wrong; 80% keeps a real
+        // recapture usable while a smaller overlap (e.g. a genuinely different display
+        // swapped in) still throws.
+        let rect: CGRect
+        if display.frame.contains(region.rect) {
+            rect = region.rect
+        } else {
+            let overlap = display.frame.intersection(region.rect)
+            let originalArea = region.rect.width * region.rect.height
+            let overlapArea = overlap.width * overlap.height
+            if originalArea > 0 && overlapArea / originalArea >= 0.8 {
+                rect = overlap
+            } else {
+                throw ShotdeckError.displayNoLongerConnected(displayID: region.displayID)
+            }
+        }
+
+        let localRect = CGRect(
+            x: rect.minX - display.frame.minX,
+            y: rect.minY - display.frame.minY,
+            width: rect.width,
+            height: rect.height
+        )
+
+        guard let mode = CGDisplayCopyDisplayMode(region.displayID) else {
+            throw ShotdeckError.captureFailed(
+                underlying: "no display mode for displayID \(region.displayID)"
+            )
+        }
+        guard mode.width > 0 else {
+            throw ShotdeckError.captureFailed(
+                underlying: "display mode width is 0 for displayID \(region.displayID)"
+            )
+        }
+        let scale = CGFloat(mode.pixelWidth) / CGFloat(mode.width)
+
+        let filter = SCContentFilter(display: display, excludingWindows: [])
+        let configuration = SCStreamConfiguration()
+        configuration.sourceRect = localRect
+        configuration.width = Int((localRect.width * scale).rounded())
+        configuration.height = Int((localRect.height * scale).rounded())
+        configuration.scalesToFit = false
+        configuration.showsCursor = false
+
+        let cgImage: CGImage
+        do {
+            cgImage = try await SCScreenshotManager.captureImage(
+                contentFilter: filter,
+                configuration: configuration
+            )
+        } catch {
+            throw ShotdeckError.captureFailed(underlying: error.localizedDescription)
+        }
+
+        let data = NSMutableData()
+        guard let dest = CGImageDestinationCreateWithData(
+            data,
+            UTType.png.identifier as CFString,
+            1,
+            nil
+        ) else {
+            throw ShotdeckError.captureFailed(underlying: "could not create PNG image destination")
+        }
+        CGImageDestinationAddImage(dest, cgImage, nil)
+        guard CGImageDestinationFinalize(dest) else {
+            throw ShotdeckError.captureFailed(underlying: "PNG encoding failed to finalize")
+        }
+
+        return CapturedImage(
+            pngData: data as Data,
+            pixelWidth: cgImage.width,
+            pixelHeight: cgImage.height,
+            scale: scale
+        )
+    }
+}

Sources/ShotdeckCore/Spool/SpoolStore.swift

@@ -0,0 +1,418 @@
+import Foundation
+import ImageIO
+import CoreGraphics
+import Darwin
+
+public actor SpoolStore {
+    private let paths: AppSupportPaths
+    private var openSession: CaptureSession
+
+    public init(paths: AppSupportPaths) throws {
+        self.paths = paths
+        let fm = FileManager.default
+        try Self.supersedeSpoolArchiveOverlaps(paths: paths, fileManager: fm)
+        try Self.finishInterruptedArchives(paths: paths, fileManager: fm)
+        let remainingIDs = try Self.listUUIDDirectories(in: paths.spool, fileManager: fm)
+        if remainingIDs.isEmpty {
+            self.openSession = try Self.createFreshSession(paths: paths)
+        } else {
+            var candidates: [CaptureSession] = []
+            for id in remainingIDs {
+                let dir = paths.sessionDirectory(id)
+                candidates.append(
+                    try Self.reconcileSessionDirectory(
+                        at: dir, id: id, assumedStateIfRebuilt: .open, fileManager: fm))
+            }
+            self.openSession = Self.pickNewest(first: candidates[0], rest: Array(candidates.dropFirst()))
+        }
+    }
+
+    /// The session currently accepting captures. Cheap accessor — all reconciliation already
+    /// happened once, inside init.
+    public func currentSession() throws -> CaptureSession {
+        openSession
+    }
+
+    /// Writes `pngData` to disk and fsyncs it BEFORE the manifest is touched, then updates and
+    /// durably writes the manifest. Order is non-negotiable: image durable -> manifest durable
+    /// -> return. Uses AtomicFile.write/writeJSON for both writes — never Data.write(to:).
+    public func append(
+        pngData: Data, pixelWidth: Int, pixelHeight: Int,
+        scale: CGFloat, capturedAt: Date
+    ) throws -> Capture {
+        let captureID = UUID()
+        let sequence = openSession.nextSequence
+        let fileName = "\(String(format: "%03d", sequence))-\(Self.hexSuffix(captureID)).png"
+        let sessionDir = paths.sessionDirectory(openSession.id)
+        let fileURL = sessionDir.appendingPathComponent(fileName)
+        try AtomicFile.write(pngData, to: fileURL)
+        let capture = Capture(
+            id: captureID, sequence: sequence, fileName: fileName,
+            pixelWidth: pixelWidth, pixelHeight: pixelHeight,
+            scale: scale, capturedAt: capturedAt)
+        let updated = openSession.appending(capture)
+        try AtomicFile.writeJSON(updated, to: sessionDir.appendingPathComponent("session.json"))
+        openSession = updated
+        return capture
+    }
+
+    /// D-11: moves the capture's PNG into `<sessionDir>/removed/` (created lazily) and drops
+    /// its manifest entry. NEVER unlinks/deletes a user PNG. Throws (no filesystem change) if
+    /// `captureID` is not present in the open session.
+    public func remove(captureID: UUID) throws -> CaptureSession {
+        guard let capture = openSession.captures.first(where: { $0.id == captureID }) else {
+            throw ShotdeckError.spoolWriteFailed(
+                path: paths.sessionDirectory(openSession.id).path,
+                underlying: "capture \(captureID) is not in the open session")
+        }
+        let sessionDir = paths.sessionDirectory(openSession.id)
+        let removedDir = sessionDir.appendingPathComponent("removed", isDirectory: true)
+        do {
+            try FileManager.default.createDirectory(at: removedDir, withIntermediateDirectories: true)
+        } catch {
+            throw ShotdeckError.spoolWriteFailed(path: removedDir.path, underlying: error.localizedDescription)
+        }
+        let sourceURL = sessionDir.appendingPathComponent(capture.fileName)
+        let destURL = removedDir.appendingPathComponent(capture.fileName)
+        guard rename(sourceURL.path, destURL.path) == 0 else {
+            throw ShotdeckError.spoolWriteFailed(
+                path: destURL.path,
+                underlying: "could not move the capture into removed/: \(String(cString: strerror(errno)))")
+        }
+        try AtomicFile.fsyncDirectory(at: removedDir)
+        let updated = openSession.removing(captureID: captureID)
+        try AtomicFile.writeJSON(updated, to: sessionDir.appendingPathComponent("session.json"))
+        openSession = updated
+        return updated
+    }
+
+    /// Closes the open session (must be non-empty), moves its directory under archive/, records
+    /// pdfFileName, and starts a fresh empty open session. Returns the archived one.
+    public func archiveCurrent(pdfFileName: String) throws -> CaptureSession {
+        guard !openSession.isEmpty else {
+            throw ShotdeckError.spoolWriteFailed(
+                path: paths.sessionDirectory(openSession.id).path,
+                underlying: "cannot archive an empty session")
+        }
+        let archived = openSession.markArchived(pdfFileName: pdfFileName)
+        let sessionDir = paths.sessionDirectory(openSession.id)
+        try AtomicFile.writeJSON(archived, to: sessionDir.appendingPathComponent("session.json"))
+        let archiveDir = paths.archiveDirectory(openSession.id)
+        guard rename(sessionDir.path, archiveDir.path) == 0 else {
+            throw ShotdeckError.spoolWriteFailed(
+                path: sessionDir.path,
+                underlying: "could not move the session into archive/: \(String(cString: strerror(errno)))")
+        }
+        try AtomicFile.fsyncDirectory(at: paths.archive)
+        let fresh = try Self.createFreshSession(paths: paths)
+        openSession = fresh
+        return archived
+    }
+
+    /// Abandons the open session only if it is empty (mints a new id/dir/manifest); throws,
+    /// with no filesystem change, if the open session has captures.
+    public func startNewSession() throws -> CaptureSession {
+        guard openSession.isEmpty else {
+            throw ShotdeckError.spoolWriteFailed(
+                path: paths.sessionDirectory(openSession.id).path,
+                underlying: "cannot start a new session: \(openSession.captures.count) capture(s) present in the open session")
+        }
+        let fresh = try Self.createFreshSession(paths: paths)
+        openSession = fresh
+        return fresh
+    }
+
+    /// Absolute URL of a capture's PNG, in whichever top-level directory its session lives
+    /// (spool/ if session.state == .open, archive/ if .archived).
+    public func imageURL(for capture: Capture, in session: CaptureSession) -> URL {
+        let dir = session.state == .open ? paths.sessionDirectory(session.id) : paths.archiveDirectory(session.id)
+        return dir.appendingPathComponent(capture.fileName)
+    }
+
+    /// Archived sessions, newest createdAt first. Lazily reconciles each archive/ directory
+    /// the same way init reconciles spool/ candidates (orphan recovery, missing-drop, corrupt
+    /// rebuild) — an archived session's manifest can degrade too and must self-heal without
+    /// ever losing a PNG.
+    public func archivedSessions() throws -> [CaptureSession] {
+        let ids = try Self.listUUIDDirectories(in: paths.archive, fileManager: .default)
+        var sessions: [CaptureSession] = []
+        for id in ids {
+            sessions.append(
+                try Self.reconcileSessionDirectory(
+                    at: paths.archiveDirectory(id), id: id, assumedStateIfRebuilt: .archived, fileManager: .default))
+        }
+        return sessions.sorted { ($0.createdAt, $0.id.uuidString) > ($1.createdAt, $1.id.uuidString) }
+    }
+
+    // MARK: - Reconciliation (static so they can run inside init)
+
+    private static func listUUIDDirectories(in parent: URL, fileManager: FileManager) throws -> [UUID] {
+        let entries: [URL]
+        do {
+            entries = try fileManager.contentsOfDirectory(
+                at: parent,
+                includingPropertiesForKeys: [.isDirectoryKey],
+                options: [])
+        } catch {
+            throw ShotdeckError.spoolWriteFailed(path: parent.path, underlying: error.localizedDescription)
+        }
+        var ids: [UUID] = []
+        for url in entries {
+            let isDirectory = (try? url.resourceValues(forKeys: [.isDirectoryKey]).isDirectory) ?? false
+            guard isDirectory else { continue }
+            if let id = UUID(uuidString: url.lastPathComponent) {
+                ids.append(id)
+            }
+        }
+        return ids
+    }
+
+    private static func supersedeSpoolArchiveOverlaps(paths: AppSupportPaths, fileManager: FileManager) throws {
+        let spoolIDs = Set(try listUUIDDirectories(in: paths.spool, fileManager: fileManager))
+        let archiveIDs = Set(try listUUIDDirectories(in: paths.archive, fileManager: fileManager))
+        for id in spoolIDs.intersection(archiveIDs) {
+            let spoolDir = paths.sessionDirectory(id)
+            let supersededDir = paths.spool.appendingPathComponent(
+                "\(id.uuidString).superseded-\(DubaiTime.fileStamp(Date()))", isDirectory: true)
+            guard rename(spoolDir.path, supersededDir.path) == 0 else {
+                throw ShotdeckError.spoolWriteFailed(
+                    path: spoolDir.path,
+                    underlying: "could not supersede a duplicate spool copy: \(String(cString: strerror(errno)))")
+            }
+            try AtomicFile.fsyncDirectory(at: paths.spool)
+            Log.spool.warning("Found session \(id.uuidString, privacy: .public) in both spool/ and archive/; kept the archive copy and superseded the spool copy — nothing was deleted.")
+        }
+    }
+
+    private static func finishInterruptedArchives(paths: AppSupportPaths, fileManager: FileManager) throws {
+        for id in try listUUIDDirectories(in: paths.spool, fileManager: fileManager) {
+            let spoolDir = paths.sessionDirectory(id)
+            let manifestURL = spoolDir.appendingPathComponent("session.json")
+            guard let data = try? Data(contentsOf: manifestURL),
+                  let decoded = try? decodeSession(from: data),
+                  decoded.id == id, decoded.state == .archived
+            else { continue }
+            let archiveDir = paths.archiveDirectory(id)
+            guard rename(spoolDir.path, archiveDir.path) == 0 else {
+                throw ShotdeckError.spoolWriteFailed(
+                    path: spoolDir.path,
+                    underlying: "could not complete an interrupted archive move: \(String(cString: strerror(errno)))")
+            }
+            try AtomicFile.fsyncDirectory(at: paths.archive)
+            Log.spool.warning("Completed an archive move for \(id.uuidString, privacy: .public) that was interrupted before this launch.")
+        }
+    }
+
+    private static func reconcileSessionDirectory(
+        at dir: URL,
+        id: UUID,
+        assumedStateIfRebuilt: SessionState,
+        fileManager: FileManager
+    ) throws -> CaptureSession {
+        let manifestURL = dir.appendingPathComponent("session.json")
+        let decoded: CaptureSession?
+        if let data = try? Data(contentsOf: manifestURL),
+           let session = try? decodeSession(from: data),
+           session.id == id {
+            decoded = session
+        } else {
+            decoded = nil
+        }
+
+        guard let session = decoded else {
+            return try rebuildManifest(
+                at: dir,
+                id: id,
+                assumedState: assumedStateIfRebuilt,
+                fileManager: fileManager)
+        }
+
+        var present: [Capture] = []
+        var missingCount = 0
+        for capture in session.captures {
+            let fileURL = dir.appendingPathComponent(capture.fileName)
+            if fileManager.fileExists(atPath: fileURL.path) {
+                present.append(capture)
+            } else {
+                missingCount += 1
+            }
+        }
+        let referenced = Set(session.captures.map(\.fileName))
+        let pngs = try listCapturePNGs(in: dir, fileManager: fileManager)
+        var recoveredOrphans: [Capture] = []
+        for pngURL in pngs where !referenced.contains(pngURL.lastPathComponent) {
+            if let recovered = recoverCapture(from: pngURL, fileManager: fileManager) {
+                recoveredOrphans.append(recovered)
+            } else {
+                Log.spool.error("Could not decode orphan PNG at \(pngURL.path, privacy: .public); leaving it on disk.")
+            }
+        }
+        let deletedTmp = deleteStrayTmpFiles(in: dir, fileManager: fileManager)
+        if missingCount == 0 && recoveredOrphans.isEmpty && !deletedTmp {
+            return session
+        }
+        let finalCaptures = (present + recoveredOrphans).sorted { $0.sequence < $1.sequence }
+        let updated = CaptureSession(
+            id: session.id,
+            createdAt: session.createdAt,
+            state: session.state,
+            captures: finalCaptures,
+            pdfFileName: session.pdfFileName)
+        try AtomicFile.writeJSON(updated, to: manifestURL)
+        Log.spool.warning("Reconciled session \(id.uuidString, privacy: .public): dropped \(missingCount) missing PNG(s), recovered \(recoveredOrphans.count) orphan(s).")
+        return updated
+    }
+
+    private static func rebuildManifest(
+        at dir: URL,
+        id: UUID,
+        assumedState: SessionState,
+        fileManager: FileManager
+    ) throws -> CaptureSession {
+        let manifestURL = dir.appendingPathComponent("session.json")
+        if fileManager.fileExists(atPath: manifestURL.path) {
+            let corruptURL = dir.appendingPathComponent(
+                "session.json.corrupt-\(DubaiTime.fileStamp(Date()))")
+            do {
+                try fileManager.moveItem(at: manifestURL, to: corruptURL)
+            } catch {
+                throw ShotdeckError.spoolWriteFailed(
+                    path: manifestURL.path,
+                    underlying: "could not quarantine a corrupt manifest: \(error.localizedDescription)")
+            }
+        }
+
+        var recovered: [Capture] = []
+        for pngURL in try listCapturePNGs(in: dir, fileManager: fileManager) {
+            if let capture = recoverCapture(from: pngURL, fileManager: fileManager) {
+                recovered.append(capture)
+            } else {
+                Log.spool.error("Could not decode PNG at \(pngURL.path, privacy: .public) while rebuilding the manifest; leaving it on disk.")
+            }
+        }
+        _ = deleteStrayTmpFiles(in: dir, fileManager: fileManager)
+        recovered.sort { $0.sequence < $1.sequence }
+
+        let createdAt: Date
+        if let earliest = recovered.map(\.capturedAt).min() {
+            createdAt = earliest
+        } else {
+            createdAt = (try? dir.resourceValues(forKeys: [.creationDateKey]))?.creationDate ?? Date()
+        }
+
+        let rebuilt = CaptureSession(
+            id: id,
+            createdAt: createdAt,
+            state: assumedState,
+            captures: recovered,
+            pdfFileName: nil)
+        try AtomicFile.writeJSON(rebuilt, to: dir.appendingPathComponent("session.json"))
+        Log.spool.warning("Rebuilt manifest for \(id.uuidString, privacy: .public) from \(recovered.count) recovered PNG(s).")
+        if assumedState == .archived {
+            Log.spool.warning("Rebuilt an archived session \(id.uuidString, privacy: .public) from PNGs; pdfFileName could not be recovered.")
+        }
+        return rebuilt
+    }
+
+    private static func recoverCapture(from fileURL: URL, fileManager: FileManager) -> Capture? {
+        guard fileManager.fileExists(atPath: fileURL.path) else { return nil }
+        guard let source = CGImageSourceCreateWithURL(fileURL as CFURL, nil),
+              let properties = CGImageSourceCopyPropertiesAtIndex(source, 0, nil) as NSDictionary?,
+              let width = (properties[kCGImagePropertyPixelWidth] as? NSNumber)?.intValue,
+              let height = (properties[kCGImagePropertyPixelHeight] as? NSNumber)?.intValue
+        else { return nil }
+        let name = fileURL.lastPathComponent
+        let sequence = Int(name.prefix(3)) ?? 1
+        let capturedAt = (try? fileURL.resourceValues(forKeys: [.creationDateKey]))?.creationDate ?? Date()
+        return Capture(
+            id: UUID(),
+            sequence: sequence,
+            fileName: name,
+            pixelWidth: width,
+            pixelHeight: height,
+            scale: 1.0,
+            capturedAt: capturedAt)
+    }
+
+    private static func pickNewest(first: CaptureSession, rest: [CaptureSession]) -> CaptureSession {
+        rest.reduce(first) { current, candidate in
+            let currentKey = (current.createdAt, current.id.uuidString)
+            let candidateKey = (candidate.createdAt, candidate.id.uuidString)
+            return candidateKey > currentKey ? candidate : current
+        }
+    }
+
+    private static func createFreshSession(paths: AppSupportPaths) throws -> CaptureSession {
+        let id = UUID()
+        let createdAt = Date()
+        let dir = paths.sessionDirectory(id)
+        do {
+            try FileManager.default.createDirectory(at: dir, withIntermediateDirectories: true)
+        } catch {
+            throw ShotdeckError.spoolWriteFailed(path: dir.path, underlying: error.localizedDescription)
+        }
+        let session = CaptureSession(id: id, createdAt: createdAt, state: .open, captures: [], pdfFileName: nil)
+        try AtomicFile.writeJSON(session, to: dir.appendingPathComponent("session.json"))
+        return session
+    }
+
+    private static func hexSuffix(_ id: UUID) -> String {
+        String(id.uuidString.replacingOccurrences(of: "-", with: "").prefix(8)).uppercased()
+    }
+
+    private static func decodeSession(from data: Data) throws -> CaptureSession {
+        let decoder = JSONDecoder()
+        decoder.dateDecodingStrategy = .iso8601
+        return try decoder.decode(CaptureSession.self, from: data)
+    }
+
+    private static func isCapturePNGName(_ name: String) -> Bool {
+        guard name.hasSuffix(".png") else { return false }
+        let stem = String(name.dropLast(4))
+        let parts = stem.split(separator: "-", maxSplits: 1, omittingEmptySubsequences: false)
+        guard parts.count == 2,
+              parts[0].count == 3,
+              parts[0].allSatisfy(\.isNumber),
+              parts[1].count == 8,
+              parts[1].allSatisfy(\.isHexDigit)
+        else { return false }
+        return true
+    }
+
+    private static func listCapturePNGs(in dir: URL, fileManager: FileManager) throws -> [URL] {
+        let entries: [URL]
+        do {
+            entries = try fileManager.contentsOfDirectory(
+                at: dir,
+                includingPropertiesForKeys: [.isDirectoryKey],
+                options: [])
+        } catch {
+            throw ShotdeckError.spoolWriteFailed(path: dir.path, underlying: error.localizedDescription)
+        }
+        return entries.filter { url in
+            let isDirectory = (try? url.resourceValues(forKeys: [.isDirectoryKey]).isDirectory) ?? false
+            guard !isDirectory else { return false }
+            return isCapturePNGName(url.lastPathComponent)
+        }
+    }
+
+    private static func deleteStrayTmpFiles(in dir: URL, fileManager: FileManager) -> Bool {
+        let entries = (try? fileManager.contentsOfDirectory(
+            at: dir,
+            includingPropertiesForKeys: [.isDirectoryKey],
+            options: [])) ?? []
+        var deleted = false
+        for url in entries {
+            guard url.lastPathComponent.hasSuffix(".tmp") else { continue }
+            let isDirectory = (try? url.resourceValues(forKeys: [.isDirectoryKey]).isDirectory) ?? false
+            guard !isDirectory else { continue }
+            do {
+                try fileManager.removeItem(at: url)
+                deleted = true
+            } catch {
+                Log.spool.error("Could not remove stray temp file at \(url.path, privacy: .public): \(error.localizedDescription, privacy: .public)")
+            }
+        }
+        return deleted
+    }
+}

Tests/ShotdeckCoreTests/SpoolStoreTests.swift

@@ -0,0 +1,590 @@
+import CoreGraphics
+import Foundation
+import ImageIO
+import Testing
+import ShotdeckCore
+
+// MARK: - 1. append writes a real, decodable PNG
+
+@Test
+func appendWritesARealDecodablePNGMatchingSourceDimensions() async throws {
+    let (root, paths) = try makeIsolatedPaths()
+    defer { try? FileManager.default.removeItem(at: root) }
+
+    let width = 12
+    let height = 7
+    let png = try makePNGData(width: width, height: height, red: 0.9, green: 0.1, blue: 0.2)
+    let store = try SpoolStore(paths: paths)
+    let capturedAt = Date(timeIntervalSince1970: 1_700_000_000)
+    let capture = try await store.append(
+        pngData: png, pixelWidth: width, pixelHeight: height, scale: 2.0, capturedAt: capturedAt)
+    let session = try await store.currentSession()
+
+    #expect(capture.pixelWidth == width)
+    #expect(capture.pixelHeight == height)
+
+    let url = await store.imageURL(for: capture, in: session)
+    let expected = paths.sessionDirectory(session.id).appendingPathComponent(capture.fileName)
+    #expect(url.path == expected.path)
+    #expect(FileManager.default.fileExists(atPath: url.path))
+
+    let onDisk = try Data(contentsOf: url)
+    #expect(onDisk == png)
+    let decoded = try #require(pngDimensions(at: url))
+    #expect(decoded.width == width)
+    #expect(decoded.height == height)
+}
+
+// MARK: - 2. remaining-manifest sequence rule (coordinator correction)
+
+@Test
+func sequencesFollowRemainingManifestMaxAndAreNotRenumbered() async throws {
+    let (root, paths) = try makeIsolatedPaths()
+    defer { try? FileManager.default.removeItem(at: root) }
+
+    let store = try SpoolStore(paths: paths)
+    let c1 = try await store.append(
+        pngData: try makePNGData(width: 4, height: 4, red: 1, green: 0, blue: 0),
+        pixelWidth: 4, pixelHeight: 4, scale: 1.0, capturedAt: Date())
+    let c2 = try await store.append(
+        pngData: try makePNGData(width: 6, height: 4, red: 0, green: 1, blue: 0),
+        pixelWidth: 6, pixelHeight: 4, scale: 1.0, capturedAt: Date())
+    let c3 = try await store.append(
+        pngData: try makePNGData(width: 8, height: 4, red: 0, green: 0, blue: 1),
+        pixelWidth: 8, pixelHeight: 4, scale: 1.0, capturedAt: Date())
+    #expect(c1.sequence == 1)
+    #expect(c2.sequence == 2)
+    #expect(c3.sequence == 3)
+
+    _ = try await store.remove(captureID: c2.id)
+    let afterMiddle = try await store.currentSession()
+    #expect(afterMiddle.captures.map(\.sequence) == [1, 3])
+    #expect(afterMiddle.captures.map(\.id) == [c1.id, c3.id])
+
+    let c4 = try await store.append(
+        pngData: try makePNGData(width: 10, height: 4, red: 1, green: 1, blue: 0),
+        pixelWidth: 10, pixelHeight: 4, scale: 1.0, capturedAt: Date())
+    #expect(c4.sequence == 4)
+
+    _ = try await store.remove(captureID: c4.id)
+    let afterLast = try await store.currentSession()
+    #expect(afterLast.captures.map(\.sequence) == [1, 3])
+
+    let c4b = try await store.append(
+        pngData: try makePNGData(width: 12, height: 4, red: 1, green: 0, blue: 1),
+        pixelWidth: 12, pixelHeight: 4, scale: 1.0, capturedAt: Date())
+    #expect(c4b.sequence == 4)
+    #expect(c4b.fileName != c4.fileName)
+    #expect(c4b.id != c4.id)
+
+    let sessionDir = paths.sessionDirectory(afterLast.id)
+    #expect(FileManager.default.fileExists(atPath: sessionDir.appendingPathComponent(c4b.fileName).path))
+    #expect(FileManager.default.fileExists(
+        atPath: sessionDir.appendingPathComponent("removed", isDirectory: true)
+            .appendingPathComponent(c4.fileName).path))
+    #expect(!FileManager.default.fileExists(atPath: sessionDir.appendingPathComponent(c4.fileName).path))
+}
+
+// MARK: - 3. remove moves PNG into removed/
+
+@Test
+func removeMovesThePNGUnchangedIntoRemovedAndLeavesTheOriginalPathEmpty() async throws {
+    let (root, paths) = try makeIsolatedPaths()
+    defer { try? FileManager.default.removeItem(at: root) }
+
+    let store = try SpoolStore(paths: paths)
+    let png = try makePNGData(width: 8, height: 5, red: 0.2, green: 0.5, blue: 0.8)
+    let capture = try await store.append(
+        pngData: png, pixelWidth: 8, pixelHeight: 5, scale: 2.0, capturedAt: Date())
+    let session = try await store.currentSession()
+    let sessionDir = paths.sessionDirectory(session.id)
+    let originalURL = sessionDir.appendingPathComponent(capture.fileName)
+    let removedURL = sessionDir.appendingPathComponent("removed", isDirectory: true)
+        .appendingPathComponent(capture.fileName)
+
+    let updated = try await store.remove(captureID: capture.id)
+
+    #expect(updated.captures.contains(where: { $0.id == capture.id }) == false)
+    #expect(!FileManager.default.fileExists(atPath: originalURL.path))
+    #expect(FileManager.default.fileExists(atPath: removedURL.path))
+    let moved = try Data(contentsOf: removedURL)
+    #expect(moved == png)
+}
+
+// MARK: - 4. remove of unknown id throws with zero filesystem change
+
+@Test
+func removeOfUnknownIDThrowsAndLeavesDiskByteIdentical() async throws {
+    let (root, paths) = try makeIsolatedPaths()
+    defer { try? FileManager.default.removeItem(at: root) }
+
+    let store = try SpoolStore(paths: paths)
+    _ = try await store.append(
+        pngData: try makePNGData(width: 4, height: 4, red: 0.1, green: 0.2, blue: 0.3),
+        pixelWidth: 4, pixelHeight: 4, scale: 1.0, capturedAt: Date())
+    let beforeSession = try await store.currentSession()
+    let beforeFiles = try snapshotFiles(under: root)
+
+    do {
+        _ = try await store.remove(captureID: UUID())
+        Issue.record("expected remove of an unknown id to throw")
+    } catch let error as ShotdeckError {
+        guard case .spoolWriteFailed = error else {
+            Issue.record("expected spoolWriteFailed, got \(error)")
+            return
+        }
+    } catch {
+        Issue.record("expected ShotdeckError, got \(error)")
+        return
+    }
+
+    let afterSession = try await store.currentSession()
+    #expect(afterSession == beforeSession)
+    let afterFiles = try snapshotFiles(under: root)
+    #expect(afterFiles == beforeFiles)
+}
+
+// MARK: - 5. orphan recovery
+
+@Test
+func orphanPNGWrittenBehindTheStoreIsRecoveredOnReopen() async throws {
+    let (root, paths) = try makeIsolatedPaths()
+    defer { try? FileManager.default.removeItem(at: root) }
+
+    let store = try SpoolStore(paths: paths)
+    let session = try await store.currentSession()
+    let width = 11
+    let height = 9
+    let png = try makePNGData(width: width, height: height, red: 0.4, green: 0.7, blue: 0.1)
+    let orphanName = "007-ABCD1234.png"
+    let dest = paths.sessionDirectory(session.id).appendingPathComponent(orphanName)
+    try AtomicFile.write(png, to: dest)
+
+    let reopened = try SpoolStore(paths: paths)
+    let recovered = try await reopened.currentSession()
+    let match = try #require(recovered.captures.first { $0.fileName == orphanName })
+    #expect(match.pixelWidth == width)
+    #expect(match.pixelHeight == height)
+    #expect(match.sequence == 7)
+    #expect(match.scale == 1.0)
+}
+
+// MARK: - 6. removed/ files are not resurrected
+
+@Test
+func orphanRecoveryDoesNotResurrectFilesInRemoved() async throws {
+    let (root, paths) = try makeIsolatedPaths()
+    defer { try? FileManager.default.removeItem(at: root) }
+
+    let store = try SpoolStore(paths: paths)
+    let session = try await store.currentSession()
+    let sessionDir = paths.sessionDirectory(session.id)
+    let removedDir = sessionDir.appendingPathComponent("removed", isDirectory: true)
+    try FileManager.default.createDirectory(at: removedDir, withIntermediateDirectories: true)
+    let hiddenName = "009-FEEDFACE.png"
+    try AtomicFile.write(
+        try makePNGData(width: 5, height: 5, red: 0.9, green: 0.9, blue: 0.1),
+        to: removedDir.appendingPathComponent(hiddenName))
+
+    let reopened = try SpoolStore(paths: paths)
+    let reconciled = try await reopened.currentSession()
+    #expect(reconciled.captures.contains(where: { $0.fileName == hiddenName }) == false)
+    #expect(FileManager.default.fileExists(atPath: removedDir.appendingPathComponent(hiddenName).path))
+}
+
+// MARK: - 7. missing-image drop
+
+@Test
+func missingPNGReferencedByManifestIsDroppedAndOthersSurvive() async throws {
+    let (root, paths) = try makeIsolatedPaths()
+    defer { try? FileManager.default.removeItem(at: root) }
+
+    let store = try SpoolStore(paths: paths)
+    let keep = try await store.append(
+        pngData: try makePNGData(width: 6, height: 6, red: 0.1, green: 0.8, blue: 0.2),
+        pixelWidth: 6, pixelHeight: 6, scale: 1.0, capturedAt: Date())
+    let drop = try await store.append(
+        pngData: try makePNGData(width: 7, height: 7, red: 0.8, green: 0.1, blue: 0.2),
+        pixelWidth: 7, pixelHeight: 7, scale: 1.0, capturedAt: Date())
+    let session = try await store.currentSession()
+    try FileManager.default.removeItem(
+        at: paths.sessionDirectory(session.id).appendingPathComponent(drop.fileName))
+
+    let reopened = try SpoolStore(paths: paths)
+    let reconciled = try await reopened.currentSession()
+    #expect(reconciled.captures.map(\.id) == [keep.id])
+    #expect(reconciled.captures.contains(where: { $0.id == drop.id }) == false)
+}
+
+// MARK: - 8. corrupt manifest rebuild
+
+@Test
+func corruptManifestIsQuarantinedAndPNGsAreRebuiltIntoANewManifest() async throws {
+    let (root, paths) = try makeIsolatedPaths()
+    defer { try? FileManager.default.removeItem(at: root) }
+
+    let store = try SpoolStore(paths: paths)
+    let first = try await store.append(
+        pngData: try makePNGData(width: 8, height: 6, red: 0.3, green: 0.3, blue: 0.9),
+        pixelWidth: 8, pixelHeight: 6, scale: 2.0, capturedAt: Date())
+    let second = try await store.append(
+        pngData: try makePNGData(width: 9, height: 6, red: 0.9, green: 0.3, blue: 0.3),
+        pixelWidth: 9, pixelHeight: 6, scale: 2.0, capturedAt: Date())
+    let session = try await store.currentSession()
+    let sessionDir = paths.sessionDirectory(session.id)
+    let manifestURL = sessionDir.appendingPathComponent("session.json")
+    let garbage = Data("{ not json".utf8)
+    try AtomicFile.write(garbage, to: manifestURL)
+
+    let reopened = try SpoolStore(paths: paths)
+    let rebuilt = try await reopened.currentSession()
+    #expect(rebuilt.id == session.id)
+
+    let contents = try FileManager.default.contentsOfDirectory(at: sessionDir, includingPropertiesForKeys: nil)
+    let corruptFiles = contents.filter { $0.lastPathComponent.hasPrefix("session.json.corrupt-") }
+    #expect(corruptFiles.count == 1)
+    let quarantined = try Data(contentsOf: try #require(corruptFiles.first))
+    #expect(quarantined == garbage)
+
+    let names = Set(rebuilt.captures.map(\.fileName))
+    #expect(names.contains(first.fileName))
+    #expect(names.contains(second.fileName))
+    let recoveredFirst = try #require(rebuilt.captures.first { $0.fileName == first.fileName })
+    #expect(recoveredFirst.pixelWidth == 8)
+    #expect(recoveredFirst.pixelHeight == 6)
+}
+
+// MARK: - 9. archiveCurrent moves the directory
+
+@Test
+func archiveCurrentMovesTheSessionUnderArchiveAndOpensAFreshEmptySession() async throws {
+    let (root, paths) = try makeIsolatedPaths()
+    defer { try? FileManager.default.removeItem(at: root) }
+
+    let store = try SpoolStore(paths: paths)
+    let png = try makePNGData(width: 10, height: 8, red: 0.5, green: 0.1, blue: 0.6)
+    let capture = try await store.append(
+        pngData: png, pixelWidth: 10, pixelHeight: 8, scale: 1.0, capturedAt: Date())
+    let open = try await store.currentSession()
+    let archived = try await store.archiveCurrent(pdfFileName: "shotdeck-review.pdf")
+
+    #expect(archived.state == .archived)
+    #expect(archived.pdfFileName == "shotdeck-review.pdf")
+    #expect(archived.id == open.id)
+    #expect(!FileManager.default.fileExists(atPath: paths.sessionDirectory(open.id).path))
+
+    let archivedPNG = paths.archiveDirectory(open.id).appendingPathComponent(capture.fileName)
+    #expect(FileManager.default.fileExists(atPath: archivedPNG.path))
+    #expect(try Data(contentsOf: archivedPNG) == png)
+
+    let current = try await store.currentSession()
+    #expect(current.id != open.id)
+    #expect(current.isEmpty)
+    #expect(current.state == .open)
+    #expect(FileManager.default.fileExists(
+        atPath: paths.sessionDirectory(current.id).appendingPathComponent("session.json").path))
+}
+
+// MARK: - 10. archiveCurrent on empty throws
+
+@Test
+func archiveCurrentOnEmptySessionThrowsAndDoesNotMoveTheDirectory() async throws {
+    let (root, paths) = try makeIsolatedPaths()
+    defer { try? FileManager.default.removeItem(at: root) }
+
+    let store = try SpoolStore(paths: paths)
+    let session = try await store.currentSession()
+    let before = try snapshotFiles(under: root)
+
+    do {
+        _ = try await store.archiveCurrent(pdfFileName: "never.pdf")
+        Issue.record("expected archiveCurrent on an empty session to throw")
+    } catch let error as ShotdeckError {
+        guard case .spoolWriteFailed = error else {
+            Issue.record("expected spoolWriteFailed, got \(error)")
+            return
+        }
+    } catch {
+        Issue.record("expected ShotdeckError, got \(error)")
+        return
+    }
+
+    #expect(FileManager.default.fileExists(atPath: paths.sessionDirectory(session.id).path))
+    #expect(try snapshotFiles(under: root) == before)
+}
+
+// MARK: - 11. interrupted-archive, both exist
+
+@Test
+func interruptedArchiveBothExistSupersedesTheSpoolCopyAndKeepsArchive() async throws {
+    let (root, paths) = try makeIsolatedPaths()
+    defer { try? FileManager.default.removeItem(at: root) }
+
+    let store = try SpoolStore(paths: paths)
+    let png = try makePNGData(width: 8, height: 8, red: 0.2, green: 0.2, blue: 0.8)
+    let capture = try await store.append(
+        pngData: png, pixelWidth: 8, pixelHeight: 8, scale: 1.0, capturedAt: Date())
+    let archived = try await store.archiveCurrent(pdfFileName: "sent.pdf")
+    let archiveDir = paths.archiveDirectory(archived.id)
+    let spoolCopy = paths.sessionDirectory(archived.id)
+    try FileManager.default.copyItem(at: archiveDir, to: spoolCopy)
+    let archivePNGBefore = try Data(contentsOf: archiveDir.appendingPathComponent(capture.fileName))
+
+    let reopened = try SpoolStore(paths: paths)
+    _ = try await reopened.currentSession()
+
+    #expect(FileManager.default.fileExists(atPath: archiveDir.path))
+    #expect(!FileManager.default.fileExists(atPath: spoolCopy.path))
+    #expect(try Data(contentsOf: archiveDir.appendingPathComponent(capture.fileName)) == archivePNGBefore)
+
+    let spoolEntries = try FileManager.default.contentsOfDirectory(
+        at: paths.spool, includingPropertiesForKeys: [.isDirectoryKey])
+    let superseded = spoolEntries.filter {
+        $0.lastPathComponent.hasPrefix("\(archived.id.uuidString).superseded-")
+    }
+    #expect(superseded.count == 1)
+    let supersededPNG = try #require(superseded.first).appendingPathComponent(capture.fileName)
+    #expect(FileManager.default.fileExists(atPath: supersededPNG.path))
+    #expect(try Data(contentsOf: supersededPNG) == png)
+}
+
+// MARK: - 12. interrupted-archive, manifest-only
+
+@Test
+func interruptedArchiveManifestOnlyCompletesTheMoveIntoArchive() async throws {
+    let (root, paths) = try makeIsolatedPaths()
+    defer { try? FileManager.default.removeItem(at: root) }
+
+    let store = try SpoolStore(paths: paths)
+    let png = try makePNGData(width: 6, height: 8, red: 0.7, green: 0.4, blue: 0.1)
+    let capture = try await store.append(
+        pngData: png, pixelWidth: 6, pixelHeight: 8, scale: 1.0, capturedAt: Date())
+    let session = try await store.currentSession()
+    let marked = session.markArchived(pdfFileName: "partial.pdf")
+    try AtomicFile.writeJSON(
+        marked, to: paths.sessionDirectory(session.id).appendingPathComponent("session.json"))
+
+    let reopened = try SpoolStore(paths: paths)
+    let current = try await reopened.currentSession()
+    #expect(current.id != session.id)
+    #expect(!FileManager.default.fileExists(atPath: paths.sessionDirectory(session.id).path))
+    let archiveDir = paths.archiveDirectory(session.id)
+    #expect(FileManager.default.fileExists(atPath: archiveDir.path))
+    #expect(FileManager.default.fileExists(atPath: archiveDir.appendingPathComponent(capture.fileName).path))
+    #expect(try Data(contentsOf: archiveDir.appendingPathComponent(capture.fileName)) == png)
+
+    let archived = try await reopened.archivedSessions()
+    #expect(archived.contains(where: { $0.id == session.id }))
+}
+
+// MARK: - 13. archivedSessions newest createdAt first
+
+@Test
+func archivedSessionsReturnsNewestCreatedAtFirst() async throws {
+    let (root, paths) = try makeIsolatedPaths()
+    defer { try? FileManager.default.removeItem(at: root) }
+
+    let newest = UUID(uuidString: "00000000-0000-4000-8000-000000000003")!
+    let oldest = UUID(uuidString: "00000000-0000-4000-8000-000000000001")!
+    let middle = UUID(uuidString: "00000000-0000-4000-8000-000000000002")!
+    let tNewest = Date(timeIntervalSince1970: 1_700_000_200)
+    let tOldest = Date(timeIntervalSince1970: 1_700_000_000)
+    let tMiddle = Date(timeIntervalSince1970: 1_700_000_100)
+
+    try seedSession(id: newest, createdAt: tNewest, state: .archived, directory: paths.archiveDirectory(newest))
+    try seedSession(id: oldest, createdAt: tOldest, state: .archived, directory: paths.archiveDirectory(oldest))
+    try seedSession(id: middle, createdAt: tMiddle, state: .archived, directory: paths.archiveDirectory(middle))
+
+    let store = try SpoolStore(paths: paths)
+    let listed = try await store.archivedSessions()
+    #expect(listed.map(\.id) == [newest, middle, oldest])
+}
+
+// MARK: - 14. newest-session tie-break by greater UUID string
+
+@Test
+func newestSessionTieBreakPicksTheLexicographicallyGreaterUUID() async throws {
+    let (root, paths) = try makeIsolatedPaths()
+    defer { try? FileManager.default.removeItem(at: root) }
+
+    let smaller = UUID(uuidString: "AAAAAAAA-AAAA-4AAA-8AAA-AAAAAAAAAAAA")!
+    let greater = UUID(uuidString: "BBBBBBBB-BBBB-4BBB-8BBB-BBBBBBBBBBBB")!
+    let createdAt = Date(timeIntervalSince1970: 1_700_000_500)
+    try seedSession(id: smaller, createdAt: createdAt, state: .open, directory: paths.sessionDirectory(smaller))
+    try seedSession(id: greater, createdAt: createdAt, state: .open, directory: paths.sessionDirectory(greater))
+
+    let first = try SpoolStore(paths: paths)
+    let firstID = try await first.currentSession().id
+    let second = try SpoolStore(paths: paths)
+    let secondID = try await second.currentSession().id
+    #expect(firstID == greater)
+    #expect(secondID == greater)
+}
+
+// MARK: - 15. filename shape
+
+@Test
+func appendFilenameMatchesSequenceDashEightHexSuffix() async throws {
+    let (root, paths) = try makeIsolatedPaths()
+    defer { try? FileManager.default.removeItem(at: root) }
+
+    let store = try SpoolStore(paths: paths)
+    let capture = try await store.append(
+        pngData: try makePNGData(width: 4, height: 3, red: 0.1, green: 0.1, blue: 0.1),
+        pixelWidth: 4, pixelHeight: 3, scale: 1.0, capturedAt: Date())
+    let hex = String(capture.id.uuidString.replacingOccurrences(of: "-", with: "").prefix(8)).uppercased()
+    #expect(capture.fileName == "001-\(hex).png")
+    let session = try await store.currentSession()
+    let url = await store.imageURL(for: capture, in: session)
+    #expect(url.lastPathComponent == capture.fileName)
+    #expect(FileManager.default.fileExists(atPath: url.path))
+}
+
+// MARK: - 16. startNewSession
+
+@Test
+func startNewSessionThrowsWhenNonEmptyAndMintsANewIdWhenEmpty() async throws {
+    let (root, paths) = try makeIsolatedPaths()
+    defer { try? FileManager.default.removeItem(at: root) }
+
+    let store = try SpoolStore(paths: paths)
+    _ = try await store.append(
+        pngData: try makePNGData(width: 5, height: 5, red: 0.4, green: 0.2, blue: 0.6),
+        pixelWidth: 5, pixelHeight: 5, scale: 1.0, capturedAt: Date())
+    let before = try snapshotFiles(under: root)
+    let occupied = try await store.currentSession()
+
+    do {
+        _ = try await store.startNewSession()
+        Issue.record("expected startNewSession to throw while captures are present")
+    } catch let error as ShotdeckError {
+        guard case .spoolWriteFailed = error else {
+            Issue.record("expected spoolWriteFailed, got \(error)")
+            return
+        }
+    } catch {
+        Issue.record("expected ShotdeckError, got \(error)")
+        return
+    }
+    #expect(try snapshotFiles(under: root) == before)
+    #expect(try await store.currentSession().id == occupied.id)
+
+    _ = try await store.remove(captureID: occupied.captures[0].id)
+    let emptyID = try await store.currentSession().id
+    let fresh = try await store.startNewSession()
+    #expect(fresh.id != emptyID)
+    #expect(fresh.isEmpty)
+    #expect(FileManager.default.fileExists(
+        atPath: paths.sessionDirectory(emptyID).appendingPathComponent("session.json").path))
+}
+
+// MARK: - 17. durability-ordering smoke test
+
+@Test
+func appendReturnsOnlyAfterThePNGBytesAreAlreadyOnDisk() async throws {
+    let (root, paths) = try makeIsolatedPaths()
+    defer { try? FileManager.default.removeItem(at: root) }
+
+    let store = try SpoolStore(paths: paths)
+    let png = try makePNGData(width: 13, height: 11, red: 0.15, green: 0.55, blue: 0.95)
+    let capture = try await store.append(
+        pngData: png, pixelWidth: 13, pixelHeight: 11, scale: 2.0, capturedAt: Date())
+    let session = try await store.currentSession()
+    let url = paths.sessionDirectory(session.id).appendingPathComponent(capture.fileName)
+    let onDisk = try Data(contentsOf: url)
+    #expect(onDisk == png)
+}
+
+// MARK: - Fixtures
+
+private func makeIsolatedPaths() throws -> (root: URL, paths: AppSupportPaths) {
+    let root = FileManager.default.temporaryDirectory
+        .appendingPathComponent("shotdeck-spool-\(UUID().uuidString)", isDirectory: true)
+    let paths = try AppSupportPaths(
+        root: root,
+        outbox: root.appendingPathComponent("outbox", isDirectory: true),
+        watchFolder: root.appendingPathComponent("watch", isDirectory: true)
+    )
+    return (root, paths)
+}
+
+private func makePNGData(
+    width: Int,
+    height: Int,
+    red: CGFloat,
+    green: CGFloat,
+    blue: CGFloat
+) throws -> Data {
+    let colorSpace = CGColorSpaceCreateDeviceRGB()
+    guard let context = CGContext(
+        data: nil,
+        width: width,
+        height: height,
+        bitsPerComponent: 8,
+        bytesPerRow: width * 4,
+        space: colorSpace,
+        bitmapInfo: CGImageAlphaInfo.premultipliedLast.rawValue
+    ) else {
+        throw FixtureError.pngGenerationFailed
+    }
+    context.setFillColor(red: red, green: green, blue: blue, alpha: 1)
+    context.fill(CGRect(x: 0, y: 0, width: width, height: height))
+    guard let image = context.makeImage() else {
+        throw FixtureError.pngGenerationFailed
+    }
+    let buffer = NSMutableData()
+    guard let destination = CGImageDestinationCreateWithData(buffer, "public.png" as CFString, 1, nil) else {
+        throw FixtureError.pngGenerationFailed
+    }
+    CGImageDestinationAddImage(destination, image, nil)
+    guard CGImageDestinationFinalize(destination) else {
+        throw FixtureError.pngGenerationFailed
+    }
+    return buffer as Data
+}
+
+private func pngDimensions(at url: URL) -> (width: Int, height: Int)? {
+    guard let source = CGImageSourceCreateWithURL(url as CFURL, nil),
+          let properties = CGImageSourceCopyPropertiesAtIndex(source, 0, nil) as NSDictionary?,
+          let width = (properties[kCGImagePropertyPixelWidth] as? NSNumber)?.intValue,
+          let height = (properties[kCGImagePropertyPixelHeight] as? NSNumber)?.intValue
+    else { return nil }
+    return (width, height)
+}
+
+private func seedSession(
+    id: UUID,
+    createdAt: Date,
+    state: SessionState,
+    directory: URL
+) throws {
+    try FileManager.default.createDirectory(at: directory, withIntermediateDirectories: true)
+    let session = CaptureSession(id: id, createdAt: createdAt, state: state, captures: [], pdfFileName: nil)
+    try AtomicFile.writeJSON(session, to: directory.appendingPathComponent("session.json"))
+}
+
+private func snapshotFiles(under root: URL) throws -> [String: Data] {
+    let fm = FileManager.default
+    var files: [String: Data] = [:]
+    guard let enumerator = fm.enumerator(
+        at: root,
+        includingPropertiesForKeys: [.isRegularFileKey],
+        options: [.skipsHiddenFiles]
+    ) else { return files }
+    let rootPath = root.standardizedFileURL.path
+    for case let url as URL in enumerator {
+        let values = try url.resourceValues(forKeys: [.isRegularFileKey])
+        guard values.isRegularFile == true else { continue }
+        var relative = url.standardizedFileURL.path
+        if relative.hasPrefix(rootPath) {
+            relative = String(relative.dropFirst(rootPath.count))
+            if relative.hasPrefix("/") { relative = String(relative.dropFirst()) }
+        }
+        files[relative] = try Data(contentsOf: url)
+    }
+    return files
+}
+
+private enum FixtureError: Error {
+    case pngGenerationFailed
+}

scripts/make-dmg.sh

@@ -0,0 +1,95 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+ROOT="$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)"
+cd "$ROOT"
+
+APP_BUNDLE="${ROOT}/.build/Shotdeck.app"
+STAGING="${ROOT}/.build/dmg-staging"
+DMG="${ROOT}/.build/Shotdeck.dmg"
+MOUNT_POINT="${ROOT}/.build/dmg-mnt"
+
+SKIP_SIGN=0
+for arg in "$@"; do
+    case "${arg}" in
+        --skip-sign)
+            SKIP_SIGN=1
+            ;;
+        *)
+            echo "Unknown argument: ${arg}" >&2
+            echo "Usage: $0 [--skip-sign]" >&2
+            exit 1
+            ;;
+    esac
+done
+
+echo "==> Building Shotdeck.app"
+if [[ "${SKIP_SIGN}" -eq 1 ]]; then
+    ./scripts/build-app.sh --skip-sign
+else
+    ./scripts/build-app.sh
+fi
+
+if [[ ! -d "${APP_BUNDLE}" ]]; then
+    echo "App bundle not found at ${APP_BUNDLE}" >&2
+    exit 1
+fi
+
+echo "==> Staging DMG contents"
+rm -rf "${STAGING}"
+mkdir -p "${STAGING}"
+ditto "${APP_BUNDLE}" "${STAGING}/Shotdeck.app"
+ln -s /Applications "${STAGING}/Applications"
+
+echo "==> Creating ${DMG}"
+mkdir -p "$(dirname "${DMG}")"
+hdiutil create -volname "Shotdeck" -srcfolder "${STAGING}" -ov -format UDZO "${DMG}"
+
+MOUNTED=0
+detach_dmg() {
+    if [[ "${MOUNTED}" -eq 1 ]]; then
+        hdiutil detach "${MOUNT_POINT}" || hdiutil detach "${MOUNT_POINT}" -force || true
+        MOUNTED=0
+    fi
+}
+trap detach_dmg EXIT
+
+if [[ -d "${MOUNT_POINT}" ]] && /sbin/mount | grep -F -q "${MOUNT_POINT}"; then
+    hdiutil detach "${MOUNT_POINT}" || hdiutil detach "${MOUNT_POINT}" -force
+fi
+rm -rf "${MOUNT_POINT}"
+mkdir -p "${MOUNT_POINT}"
+
+echo "==> Verifying ${DMG}"
+hdiutil attach "${DMG}" -nobrowse -readonly -mountpoint "${MOUNT_POINT}"
+MOUNTED=1
+
+echo "==> Mount contents"
+ls -la "${MOUNT_POINT}"
+
+if [[ ! -d "${MOUNT_POINT}/Shotdeck.app" ]]; then
+    echo "Verification failed: Shotdeck.app missing from mounted DMG" >&2
+    exit 1
+fi
+if [[ ! -L "${MOUNT_POINT}/Applications" ]]; then
+    echo "Verification failed: Applications symlink missing from mounted DMG" >&2
+    exit 1
+fi
+if [[ "$(readlink "${MOUNT_POINT}/Applications")" != "/Applications" ]]; then
+    echo "Verification failed: Applications does not point at /Applications" >&2
+    exit 1
+fi
+
+echo "==> codesign --verify --deep"
+codesign --verify --deep --verbose=2 "${MOUNT_POINT}/Shotdeck.app"
+
+echo "==> Detaching ${MOUNT_POINT}"
+hdiutil detach "${MOUNT_POINT}"
+MOUNTED=0
+trap - EXIT
+
+SHA256="$(shasum -a 256 "${DMG}" | awk '{print $1}')"
+
+echo
+echo "DMG path: ${DMG}"
+echo "SHA256: ${SHA256}"