fix(apple): recover dropped macOS client features lost in the W7/W8 refactor

The W7/W8 client refactor (extracting FullscreenController/ApprovalRequest out of
ContentView, splitting Settings) landed the DefaultsKeys + scaffolding but dropped
the feature WIRING, which was uncommitted WIP shelved in a stash during the
16:28 clipboard/v4 reconcile. Recovered from that stash (+ its untracked-files
parent for the whole new ModifierLayout.swift) and re-ported onto the refactored
tree:

- invertScroll: applied in InputCapture.sendScroll (the one scroll sink) + Settings toggle
- modifierLayout (Cmd/Option switch): restored ModifierLayout.swift enum + KeyMaps
  .applyModifierLayout + InputCapture.emitKey wire-boundary + Settings picker
- fullscreen shortcut (Ctrl+Cmd+F): InputCapture ⌃⌘F interception + onToggleFullscreen
  + StreamView wiring + Stream-menu item (the .punktfunkToggleFullscreen sink +
  FullscreenController observer already survived on main)
- render scale: Settings picker + MatchWindowFollower renderScale/maxDimension
  application + StreamView/StreamViewIOS plumbing (RenderScale.swift already on main)

StreamCommands re-ported by hand (the stash hunk deleted the since-landed clipboard
item — kept it, added the fullscreen item alongside). Recovered ModifierLayout +
RenderScale tests. swift build green; 15 tests pass.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

clients/apple/Sources/PunktfunkClient/Session/StreamCommands.swift

@@ -72,6 +72,14 @@ struct StreamCommands: Commands {
             }
             .keyboardShortcut("c", modifiers: [.control, .option, .shift])
             .disabled(session?.isStreaming != true || session?.clipboardAvailable != true)
+            // Toggle the window's fullscreen. ⌃⌘F is the macOS-standard fullscreen combo; here it's
+            // explicit so it's discoverable AND survives capture — while streaming the stream view
+            // swallows keys, so InputCapture's monitor detects the same combo and posts the same
+            // notification the key window's FullscreenController observes.
+            Button("Toggle Fullscreen") {
+                NotificationCenter.default.post(name: .punktfunkToggleFullscreen, object: nil)
+            }
+            .keyboardShortcut("f", modifiers: [.control, .command])
             #endif
             Divider()
             Button("Disconnect") { session?.disconnect() }

clients/apple/Sources/PunktfunkClient/Settings/SettingsView+Sections.swift

@@ -38,6 +38,7 @@ extension SettingsView {
             }
             #endif
             #if !os(tvOS)
+            renderScaleRow
             bitrateRows
             #endif
         } header: {
@@ -54,6 +55,50 @@ extension SettingsView {
         }
     }
 
+    #if !os(tvOS)
+    /// Render-scale picker + the resulting host resolution. > 1 supersamples (sharper, at more
+    /// bandwidth AND client decode); < 1 renders under native (lighter). The presenter resamples the
+    /// decoded frame to this display, so the multiplier is where the sharpness/cost trade-off lives.
+    @ViewBuilder var renderScaleRow: some View {
+        Picker("Render scale", selection: $renderScale) {
+            ForEach(RenderScale.presets, id: \.self) { scale in
+                Text(RenderScale.label(scale)).tag(scale)
+            }
+        }
+        // The concrete host resolution makes the cost legible. Only meaningful for the explicit mode
+        // (match-window derives the base from the live window, not these fields).
+        if renderScale != 1.0, !matchWindow {
+            let mode = RenderScale.apply(
+                baseWidth: width, baseHeight: height,
+                scale: renderScale,
+                maxDimension: RenderScale.maxDimension(codec: codec))
+            Text("Host renders \(Int(mode.width))×\(Int(mode.height)); this device downscales it to your display.")
+                .font(.geist(12, relativeTo: .caption))
+                .foregroundStyle(.secondary)
+        }
+    }
+
+    /// Keyboard & mouse forwarding — applies wherever a hardware keyboard/mouse drives the stream
+    /// (always on macOS; an attached keyboard/mouse on iPad). Absent on tvOS (no such input path).
+    @ViewBuilder var inputSection: some View {
+        Section {
+            Picker("Modifier keys", selection: $modifierLayout) {
+                ForEach(ModifierLayout.allCases, id: \.self) { layout in
+                    Text(layout.label).tag(layout.rawValue)
+                }
+            }
+            Toggle("Invert scroll direction", isOn: $invertScroll)
+        } header: {
+            Text("Keyboard & mouse")
+        } footer: {
+            Text((ModifierLayout(rawValue: modifierLayout) ?? .mac).detail
+                + " Invert scroll reverses the wheel/trackpad scroll direction sent to the host.")
+                .font(.geist(12, relativeTo: .caption))
+                .foregroundStyle(.secondary)
+        }
+    }
+    #endif
+
     #if os(iOS)
     // MARK: - Stream mode (iOS wheel)
 

clients/apple/Sources/PunktfunkClient/Settings/SettingsView.swift

@@ -1,5 +1,6 @@
-// App settings. The host creates a native virtual output at exactly the chosen size/refresh —
+// App settings. The host creates a virtual output at exactly the chosen size/refresh; the only
-// there is no scaling anywhere in the pipeline.
+// deliberate resample is the opt-in Render Scale (the host renders at size × scale and this device
+// downscales — supersampling for sharpness, or under-rendering for a lighter host/link).
 //
 // Navigation differs per platform, but all three group the same categories (General, Display,
 // Audio, Controllers, Advanced, About): macOS uses a tabbed preferences window; iOS/iPadOS uses
@@ -25,6 +26,10 @@ struct SettingsView: View {
     // windowed session instead streams at the window's native pixels (1:1, no scaling) so it stays
     // pixel-exact rather than the presenter resampling a fixed-mode frame into the window.
     @AppStorage(DefaultsKey.matchWindow) var matchWindow = false
+    // Render-resolution multiplier: the host renders/encodes at chosen-resolution × this, and the
+    // presenter downscales (> 1 = supersampling for sharpness) or upscales (< 1 = a lighter host /
+    // link). 1.0 = Native (the prior behaviour).
+    @AppStorage(DefaultsKey.renderScale) var renderScale = 1.0
     @AppStorage(DefaultsKey.compositor) var compositor = 0
     @AppStorage(DefaultsKey.gamepadType) var gamepadType = 0
     @AppStorage(DefaultsKey.bitrateKbps) var bitrateKbps = 0
@@ -51,6 +56,12 @@ struct SettingsView: View {
     @AppStorage(DefaultsKey.autoWake) var autoWakeEnabled = true
     @AppStorage(DefaultsKey.backgroundKeepAlive) var backgroundKeepAlive = false
     @AppStorage(DefaultsKey.backgroundTimeoutMinutes) var backgroundTimeoutMinutes = 10
+    #if !os(tvOS)
+    // Keyboard & mouse forwarding (macOS + a hardware keyboard/mouse on iPad). Invert-scroll flips
+    // both wheel axes; modifier-layout relocates the ⌥/⌘ → Alt/Super roles by physical position.
+    @AppStorage(DefaultsKey.invertScroll) var invertScroll = false
+    @AppStorage(DefaultsKey.modifierLayout) var modifierLayout = ModifierLayout.mac.rawValue
+    #endif
     #if DEBUG && !os(tvOS)
     @State var showControllerTest = false
     #endif
@@ -112,6 +123,7 @@ struct SettingsView: View {
         TabView {
             Form {
                 streamModeSection
+                inputSection
                 compositorSection
                 wakeSection
             }
@@ -242,6 +254,7 @@ struct SettingsView: View {
             Form {
                 streamModeSection
                 pointerSection
+                inputSection
                 compositorSection
                 wakeSection
                 keepAliveSection // iOS-only content; empty on tvOS
@@ -334,6 +347,10 @@ struct SettingsView: View {
         return ScrollView {
             VStack(spacing: 16) {
                 TVSelectionRow(title: "Stream mode", options: options, selection: modeTag)
+                TVSelectionRow(
+                    title: "Render scale",
+                    options: RenderScale.presets.map { (label: RenderScale.label($0), tag: $0) },
+                    selection: $renderScale)
                 TVSelectionRow(
                     title: "Bitrate",
                     options: SettingsOptions.bitrateOptions(current: bitrateKbps),

clients/apple/Sources/PunktfunkKit/Input/InputCapture.swift

@@ -41,6 +41,7 @@ import UIKit
 import Foundation
 import GameController
 import PunktfunkCore
+import PunktfunkShared
 import os
 
 /// Diagnostic logging for the input path. Off by default (input is high-rate); set
@@ -125,6 +126,12 @@ public final class InputCapture {
     public var onDisconnect: (() -> Void)?
     public var onCycleStats: (() -> Void)?
 
+    /// Fired on ⌃⌘F (macOS) — toggle the streaming window in/out of fullscreen. Detected in the
+    /// monitor only WHILE FORWARDING, for the same reason as the ⌃⌥⇧ combos: a captured stream view
+    /// swallows keys, so the Stream menu's identical ⌃⌘F equivalent never reaches it; released, the
+    /// menu handles it. Main queue.
+    public var onToggleFullscreen: (() -> Void)?
+
     #if os(iOS)
     /// Windows VKs of the three modifier classes in the ⌃⌥⇧Q release chord, both L/R sides:
     /// control (0xA2/0xA3), option (0xA4/0xA5), shift (0xA0/0xA1). Used to sift the HID key stream.
@@ -273,6 +280,14 @@ public final class InputCapture {
                     break
                 }
             }
+            // ⌃⌘F toggles the streaming window's fullscreen. Intercepted only while forwarding (the
+            // captured stream view swallows the menu's identical equivalent); the F is latched so its
+            // keyUp can't type into the host. keyCode 3 = kVK_ANSI_F (layout-independent).
+            if self.forwarding, flags == [.control, .command], event.keyCode == 3 /* F */ {
+                self.suppressedVK = 0x46 // VK_F — the same physical F is en route via GC
+                self.onToggleFullscreen?()
+                return nil
+            }
             return event
         }
         #endif
@@ -318,7 +333,7 @@ public final class InputCapture {
         chordModifiersDown.removeAll()
         suppressedVK = nil
         for vk in pressedVKs {
-            connection.send(.key(vk, down: false))
+            emitKey(vk, down: false)
         }
         for button in pressedButtons {
             connection.send(.mouseButton(button, down: false))
@@ -331,6 +346,15 @@ public final class InputCapture {
         residualScrollY = 0
     }
 
+    /// The single wire boundary for a key event. Every `.key` send funnels through here so the
+    /// active location-based modifier layout is applied in exactly one place while all internal
+    /// press/release bookkeeping (`pressedVKs`, `cmdKeysDown`, `resolveModifier`'s `isDown`) stays on
+    /// the physical VK. Read live from the setting so a mid-session change (rare) takes on the next
+    /// key without re-arming capture. Non-modifier VKs pass through untouched.
+    private func emitKey(_ vk: UInt32, down: Bool) {
+        connection.send(.key(Self.applyModifierLayout(vk, ModifierLayout.current), down: down))
+    }
+
     /// Release any held MOUSE buttons host-side, leaving keyboard state untouched. Used when
     /// the iPad pointer lock drops while a GCMouse button is held: by then the GCMouse release
     /// handler is gated off (`gcMouseForwarding` is false), so it can't deliver the release
@@ -399,7 +423,7 @@ public final class InputCapture {
             inputLog.debug(
                 "key \(vk, privacy: .public) \(down ? "down" : "up", privacy: .public) sent")
         }
-        connection.send(.key(vk, down: down))
+        emitKey(vk, down: down)
     }
 
     /// NSEvent modifier path (macOS): modifier keys never fire keyDown/keyUp — they arrive
@@ -566,8 +590,15 @@ public final class InputCapture {
     /// Moonlight's convention). Fed by StreamLayerView.scrollWheel — the only delivery
     /// path that covers trackpad/Magic Mouse gestures (GCMouse never reports them).
     /// Fractional remainders accumulate so slow two-finger scrolling isn't truncated away.
-    public func sendScroll(dx: Float, dy: Float) {
+    public func sendScroll(dx rawDx: Float, dy rawDy: Float) {
         guard forwarding else { return }
+        // Optionally invert both axes (read live). This is the ONE scroll sink for every platform —
+        // the macOS wheel, the iOS trackpad pan, and a GCMouse wheel all land here — so the toggle
+        // flips them consistently. Residuals are accumulated AFTER inversion so a direction change
+        // between events doesn't strand a fractional remainder of the old sign.
+        let invert = UserDefaults.standard.bool(forKey: DefaultsKey.invertScroll)
+        let dx = invert ? -rawDx : rawDx
+        let dy = invert ? -rawDy : rawDy
         let fy = dy + residualScrollY
         let fx = dx + residualScrollX
         let iy = fy.rounded(.towardZero)
@@ -643,7 +674,7 @@ public final class InputCapture {
             } else {
                 self.pressedVKs.remove(vk)
             }
-            self.connection.send(.key(vk, down: pressed))
+            self.emitKey(vk, down: pressed)
         }
         #endif
     }

clients/apple/Sources/PunktfunkKit/Input/KeyMaps.swift

@@ -1,7 +1,28 @@
 // InputCapture's static keymap tables: HID usage → Windows VK (the GCKeyboard path on all
 // platforms) and, on macOS, NSEvent.keyCode → Windows VK (the NSEvent key path).
 
+import PunktfunkShared
+
 extension InputCapture {
+    /// Remap one modifier VK for the active location-based [`ModifierLayout`] just before it goes on
+    /// the wire. `.mac` (and every non-modifier VK) is the identity. `.windows` swaps the Alt vs
+    /// Super/Windows ROLE between the Option and Command keys while KEEPING the side, so a Windows
+    /// user's `⌘ = Alt, ⌥ = Win` muscle memory lands correctly:
+    ///   L Command 0x5B ↔ L Alt 0xA4   ·   R Command 0x5C ↔ R Alt 0xA5.
+    /// It's applied ONLY at the send boundary (`InputCapture.emitKey`) — all press/release
+    /// bookkeeping stays on the physical VK, so modifier direction tracking and the client-local
+    /// ⌘-based shortcuts are untouched. The swap is its own inverse: a key that went down remapped
+    /// goes up remapped, so the host never sees a stuck modifier.
+    static func applyModifierLayout(_ vk: UInt32, _ layout: ModifierLayout) -> UInt32 {
+        guard layout == .windows else { return vk }
+        switch vk {
+        case 0x5B: return 0xA4 // L Command → L Alt (VK_LWIN → VK_LMENU)
+        case 0x5C: return 0xA5 // R Command → R Alt (VK_RWIN → VK_RMENU)
+        case 0xA4: return 0x5B // L Option  → L Win (VK_LMENU → VK_LWIN)
+        case 0xA5: return 0x5C // R Option  → R Win (VK_RMENU → VK_RWIN)
+        default: return vk
+        }
+    }
     /// HID usage (GCKeyCode raw) → Windows VK (the host maps VK → evdev; every VK emitted
     /// here exists in punktfunk-host/src/inject.rs::vk_to_evdev — extend the two together).
     static let hidToVK: [Int: UInt32] = {

clients/apple/Sources/PunktfunkKit/Video/MatchWindowFollower.swift

@@ -15,6 +15,7 @@
 // from looping request → rollback → request.
 
 import Foundation
+import PunktfunkShared
 
 /// The pure, side-effect-free core of the Match-window trigger — so the normalize/skip discipline
 /// is unit-tested without a live connection or a UI (`MatchWindowTests`).
@@ -51,6 +52,11 @@ public final class MatchWindowFollower {
     private weak var connection: PunktfunkConnection?
     private let debounce: TimeInterval
     private let minSpacing: TimeInterval
+    /// Render-scale multiplier applied to the live window size before it's requested, so the
+    /// match-window path supersamples/undersamples exactly like the fixed-mode connect. 1.0 = the
+    /// window's native pixels (the prior behaviour). `maxDimension` is the codec's per-axis ceiling.
+    private let renderScale: Double
+    private let maxDimension: Int
     private var enabled: Bool
 
     private var work: DispatchWorkItem?
@@ -74,15 +80,28 @@ public final class MatchWindowFollower {
     public init(
         connection: PunktfunkConnection,
         enabled: Bool,
+        renderScale: Double = 1.0,
+        maxDimension: Int = 8192,
         debounce: TimeInterval = 0.4,
         minSpacing: TimeInterval = 1.0
     ) {
         self.connection = connection
         self.enabled = enabled
+        self.renderScale = RenderScale.sanitize(renderScale)
+        self.maxDimension = maxDimension
         self.debounce = debounce
         self.minSpacing = minSpacing
     }
 
+    /// The host-valid mode for a live window size: the window's physical pixels × the render scale,
+    /// aspect-preserved, even, and clamped to the codec ceiling — the match-window twin of
+    /// ContentView's `scaledMode()`. Reduces to `MatchWindow.normalize` when the scale is 1.0.
+    private func targetMode(widthPx: Int, heightPx: Int) -> (width: UInt32, height: UInt32) {
+        RenderScale.apply(
+            baseWidth: widthPx, baseHeight: heightPx,
+            scale: renderScale, maxDimension: maxDimension)
+    }
+
     /// Turn following on/off live (a mid-session settings change; off cancels a pending request).
     public func setEnabled(_ on: Bool) {
         enabled = on
@@ -109,7 +128,7 @@ public final class MatchWindowFollower {
     /// mode yet → nothing to compare against, skip.
     private func reportSteering(widthPx: Int, heightPx: Int) {
         guard let connection else { return }
-        let target = MatchWindow.normalize(widthPx: widthPx, heightPx: heightPx)
+        let target = targetMode(widthPx: widthPx, heightPx: heightPx)
         let mode = connection.currentMode()
         guard mode.width > 0, mode.height > 0 else { return }
         if target.width == mode.width, target.height == mode.height {
@@ -137,7 +156,7 @@ public final class MatchWindowFollower {
             schedule()
             return
         }
-        let target = MatchWindow.normalize(widthPx: size.width, heightPx: size.height)
+        let target = targetMode(widthPx: size.width, heightPx: size.height)
         let mode = connection.currentMode()
         pendingSize = nil
         guard let req = MatchWindow.request(

clients/apple/Sources/PunktfunkKit/Views/StreamView.swift

@@ -621,6 +621,12 @@ public final class StreamLayerView: NSView {
             guard let self, self.window?.isKeyWindow == true else { return }
             self.onDisconnectRequest?()
         }
+        capture.onToggleFullscreen = { [weak self] in
+            // App-level window action: post to the key window's FullscreenController (same routing as
+            // the Stream menu's ⌃⌘F item, so captured and released states hit one code path).
+            guard self?.window?.isKeyWindow == true else { return }
+            NotificationCenter.default.post(name: .punktfunkToggleFullscreen, object: nil)
+        }
         capture.onCycleStats = { [weak self] in
             guard self?.window?.isKeyWindow == true else { return }
             // Advance the shared tier setting directly — every @AppStorage reader (the HUD's
@@ -671,7 +677,10 @@ public final class StreamLayerView: NSView {
         // default keeps the explicit mode.
         let follower = MatchWindowFollower(
             connection: connection,
-            enabled: UserDefaults.standard.object(forKey: DefaultsKey.matchWindow) as? Bool ?? false)
+            enabled: UserDefaults.standard.object(forKey: DefaultsKey.matchWindow) as? Bool ?? false,
+            renderScale: UserDefaults.standard.object(forKey: DefaultsKey.renderScale) as? Double ?? 1.0,
+            maxDimension: RenderScale.maxDimension(
+                codec: UserDefaults.standard.string(forKey: DefaultsKey.codec) ?? "auto"))
         follower.onResizeTarget = onResizeTarget // resize overlay START signal (instant, on the follower)
         matchFollower = follower
         layoutPresenter()

clients/apple/Sources/PunktfunkKit/Views/StreamViewIOS.swift

@@ -385,7 +385,10 @@ public final class StreamViewController: StreamViewControllerBase {
         // default keeps the explicit mode.
         let follower = MatchWindowFollower(
             connection: connection,
-            enabled: UserDefaults.standard.object(forKey: DefaultsKey.matchWindow) as? Bool ?? false)
+            enabled: UserDefaults.standard.object(forKey: DefaultsKey.matchWindow) as? Bool ?? false,
+            renderScale: UserDefaults.standard.object(forKey: DefaultsKey.renderScale) as? Double ?? 1.0,
+            maxDimension: RenderScale.maxDimension(
+                codec: UserDefaults.standard.string(forKey: DefaultsKey.codec) ?? "auto"))
         follower.onResizeTarget = onResizeTarget
         matchFollower = follower
         #endif

clients/apple/Sources/PunktfunkShared/ModifierLayout.swift

@@ -0,0 +1,52 @@
+// Location-based modifier mapping — which Windows VK each PHYSICAL modifier position forwards to
+// the host. A Mac keyboard's bottom row is `⌃ Control / ⌥ Option / ⌘ Command / space`; a Windows
+// keyboard's is `Ctrl / ⊞ Super / Alt / space`. So the key NEAREST the space bar is Command on a
+// Mac but Alt on Windows, and the next one out is Option on a Mac but the Windows key. A user who
+// grew up on Windows reaches for Alt where the Mac has Command; this setting lets them get that
+// muscle memory back WITHOUT relabelling keycaps — it remaps by physical position, not by a blunt
+// "swap these two VKs" that would also drag Control/Shift or lose the left/right distinction.
+//
+// The model: keep the physical detection (which side, which key) exactly as the OS reports it, and
+// swap only the Alt-vs-Super ROLE between the Option and Command keys, per side. So under `.windows`
+// the ⌘ position emits Alt (VK_L/RMENU) and the ⌥ position emits the Windows key (VK_L/RWIN), while
+// left stays left and right stays right. Control and Shift are in the same place on both keyboards,
+// so they never move. Lives in PunktfunkShared because both the Settings UI (PunktfunkClient) and
+// the wire-boundary remap (`InputCapture.applyModifierLayout`, PunktfunkKit) resolve it.
+
+import Foundation
+
+/// How the physical ⌥ Option / ⌘ Command keys map to host modifiers. The raw values are stable on
+/// disk — rename the cases freely, never the strings.
+public enum ModifierLayout: String, CaseIterable, Sendable {
+    /// Apple positions (default): ⌥ Option → Alt, ⌘ Command → Super/Windows. The current behaviour.
+    case mac
+    /// Windows positions: the key nearest the space bar (⌘ Command) → Alt, the next one (⌥ Option)
+    /// → the Windows/Super key. Side (left/right) is preserved.
+    case windows
+
+    /// User-facing label (Settings picker).
+    public var label: String {
+        switch self {
+        case .mac: return "Mac (⌥ Alt · ⌘ Super)"
+        case .windows: return "Windows (⌘ Alt · ⌥ Super)"
+        }
+    }
+
+    /// A one-line explanation for the setting's footer.
+    public var detail: String {
+        switch self {
+        case .mac:
+            return "The ⌥ Option key sends Alt and the ⌘ Command key sends the Windows key — the Apple layout."
+        case .windows:
+            return "The key nearest the space bar sends Alt and the next one sends the Windows key, matching a PC keyboard. Client shortcuts (⌘⎋ and friends) still use the physical ⌘ key."
+        }
+    }
+
+    /// The persisted layout (default `.mac` when unset).
+    public static var current: ModifierLayout {
+        guard let raw = UserDefaults.standard.string(forKey: DefaultsKey.modifierLayout) else {
+            return .mac
+        }
+        return ModifierLayout(rawValue: raw) ?? .mac
+    }
+}

clients/apple/Tests/PunktfunkKitTests/ModifierLayoutMappingTests.swift

@@ -0,0 +1,51 @@
+import XCTest
+
+import PunktfunkShared
+@testable import PunktfunkKit
+
+/// Pins the location-based modifier remap (`InputCapture.applyModifierLayout`) — the wire-boundary
+/// swap that relocates the Alt/Super role between the physical ⌥/⌘ keys per side, without touching
+/// Control/Shift or the physical detection upstream.
+final class ModifierLayoutMappingTests: XCTestCase {
+    // The four physical modifier VKs the remap can touch, and everything else it must not.
+    private let lWin: UInt32 = 0x5B, rWin: UInt32 = 0x5C
+    private let lAlt: UInt32 = 0xA4, rAlt: UInt32 = 0xA5
+
+    func testMacLayoutIsIdentity() {
+        for vk: UInt32 in [lWin, rWin, lAlt, rAlt, 0xA0, 0xA2, 0x41, 0x1B] {
+            XCTAssertEqual(InputCapture.applyModifierLayout(vk, .mac), vk)
+        }
+    }
+
+    func testWindowsLayoutSwapsAltAndSuperPerSide() {
+        XCTAssertEqual(InputCapture.applyModifierLayout(lWin, .windows), lAlt) // L ⌘ → L Alt
+        XCTAssertEqual(InputCapture.applyModifierLayout(rWin, .windows), rAlt) // R ⌘ → R Alt
+        XCTAssertEqual(InputCapture.applyModifierLayout(lAlt, .windows), lWin) // L ⌥ → L Win
+        XCTAssertEqual(InputCapture.applyModifierLayout(rAlt, .windows), rWin) // R ⌥ → R Win
+    }
+
+    func testWindowsLayoutKeepsSideNeverCrossesLeftRight() {
+        // A left key never becomes a right VK or vice-versa.
+        XCTAssertNotEqual(InputCapture.applyModifierLayout(lWin, .windows), rAlt)
+        XCTAssertNotEqual(InputCapture.applyModifierLayout(rWin, .windows), lAlt)
+    }
+
+    func testControlShiftAndRegularKeysNeverMove() {
+        for vk: UInt32 in [
+            0xA0, 0xA1, // L/R Shift
+            0xA2, 0xA3, // L/R Control
+            0x41, 0x5A, // A, Z
+            0x1B, 0x0D, // Esc, Return
+        ] {
+            XCTAssertEqual(InputCapture.applyModifierLayout(vk, .windows), vk)
+        }
+    }
+
+    func testWindowsRemapIsItsOwnInverse() {
+        // Down-remapped then the same key up-remapped land on the same host VK — no stuck modifier.
+        for vk: UInt32 in [lWin, rWin, lAlt, rAlt] {
+            let once = InputCapture.applyModifierLayout(vk, .windows)
+            XCTAssertEqual(InputCapture.applyModifierLayout(once, .windows), vk)
+        }
+    }
+}

clients/apple/Tests/PunktfunkKitTests/RenderScaleTests.swift

@@ -0,0 +1,82 @@
+import XCTest
+
+import PunktfunkShared
+
+/// Pins the render-scale geometry (`RenderScale`) — the multiply → aspect-preserve → even-floor →
+/// codec-clamp that turns the `renderScale` setting into a host-valid `Mode`, plus the label/clamp
+/// helpers the UI and the connect share.
+final class RenderScaleTests: XCTestCase {
+    func testSanitizeClampsToRangeAndDefaultsMissing() {
+        XCTAssertEqual(RenderScale.sanitize(0), 1.0) // absent / zero → Native
+        XCTAssertEqual(RenderScale.sanitize(-2), 1.0) // nonsense → Native
+        XCTAssertEqual(RenderScale.sanitize(0.1), 0.5) // below the floor
+        XCTAssertEqual(RenderScale.sanitize(9), 4.0) // above the ceiling
+        XCTAssertEqual(RenderScale.sanitize(1.5), 1.5) // in range, untouched
+    }
+
+    func testMaxDimensionIsCodecAware() {
+        XCTAssertEqual(RenderScale.maxDimension(codec: "h264"), 4096)
+        XCTAssertEqual(RenderScale.maxDimension(codec: "hevc"), 8192)
+        XCTAssertEqual(RenderScale.maxDimension(codec: "av1"), 8192)
+        XCTAssertEqual(RenderScale.maxDimension(codec: "auto"), 8192)
+    }
+
+    func testNativeScaleIsIdentity() {
+        let m = RenderScale.apply(baseWidth: 1920, baseHeight: 1080, scale: 1.0, maxDimension: 8192)
+        XCTAssertEqual(m.width, 1920)
+        XCTAssertEqual(m.height, 1080)
+    }
+
+    func testSupersampleDoubles() {
+        let m = RenderScale.apply(baseWidth: 1920, baseHeight: 1080, scale: 2.0, maxDimension: 8192)
+        XCTAssertEqual(m.width, 3840)
+        XCTAssertEqual(m.height, 2160)
+    }
+
+    func testUnderRenderHalves() {
+        let m = RenderScale.apply(baseWidth: 1920, baseHeight: 1080, scale: 0.5, maxDimension: 8192)
+        XCTAssertEqual(m.width, 960)
+        XCTAssertEqual(m.height, 540)
+    }
+
+    func testResultsAreAlwaysEven() {
+        // 1280×720 × 1.5 = 1920×1080 (already even); 1366×768 × 1.5 = 2049×1152 → 2048×1152.
+        let m = RenderScale.apply(baseWidth: 1366, baseHeight: 768, scale: 1.5, maxDimension: 8192)
+        XCTAssertEqual(m.width % 2, 0)
+        XCTAssertEqual(m.height % 2, 0)
+        XCTAssertEqual(m.width, 2048)
+        XCTAssertEqual(m.height, 1152)
+    }
+
+    func testOverCeilingClampsUniformlyPreservingAspect() {
+        // 4K × 4 would be 15360×8640; both axes exceed 8192, so the LARGER (width) lands on the cap
+        // and the ratio is kept (16:9 → 8192×4608, even).
+        let m = RenderScale.apply(baseWidth: 3840, baseHeight: 2160, scale: 4.0, maxDimension: 8192)
+        XCTAssertLessThanOrEqual(m.width, 8192)
+        XCTAssertLessThanOrEqual(m.height, 8192)
+        XCTAssertEqual(m.width, 8192)
+        XCTAssertEqual(m.height, 4608)
+        // 16:9 preserved to within the even-floor rounding.
+        XCTAssertEqual(Double(m.width) / Double(m.height), 16.0 / 9.0, accuracy: 0.01)
+    }
+
+    func testH264CeilingIsTighter() {
+        // 1080p × 4 = 7680×4320; under H.264's 4096 wall the width clamps to 4096, aspect kept.
+        let m = RenderScale.apply(baseWidth: 1920, baseHeight: 1080, scale: 4.0, maxDimension: 4096)
+        XCTAssertEqual(m.width, 4096)
+        XCTAssertEqual(m.height, 2304)
+    }
+
+    func testMinimumFloorHonoured() {
+        // A tiny base under a small scale can't fall below 320×200.
+        let m = RenderScale.apply(baseWidth: 400, baseHeight: 300, scale: 0.5, maxDimension: 8192)
+        XCTAssertGreaterThanOrEqual(m.width, 320)
+        XCTAssertGreaterThanOrEqual(m.height, 200)
+    }
+
+    func testLabels() {
+        XCTAssertEqual(RenderScale.label(1.0), "Native (1×)")
+        XCTAssertEqual(RenderScale.label(2.0), "2× · supersample")
+        XCTAssertEqual(RenderScale.label(0.5), "0.5×")
+    }
+}