0.5.0

ResponsiveLayoutKit 0.5 moves from the 0.4 phone/tablet model to Apple's
vocabulary (size classes and scene geometry) and supports every form factor:
iPhone, iPad, iPhone Duo, Mac, Mac Catalyst, and Apple Vision Pro. Nothing
breaks: every 0.4 API is still there, deprecated, and behaves as in 0.4.0.
See Migrating from Phone and Tablet Layouts
for the replacement table and before/after examples.

Added

• macOS, visionOS, and Mac Catalyst support. Platforms are now iOS 26,
  macOS 26, visionOS 26, and Mac Catalyst 26.
• UserInterfaceSizeClass.value(compact:regular:), also on the optional, so
  Apple's \.horizontalSizeClass works directly. nil resolves to .compact,
  or .regular on native macOS.
• \.sceneHorizontalSizeClass and \.sceneVerticalSizeClass: non-optional
  scene-scope size classes that don't flip inside a compact sheet or popover.
  Resolution order: the nearest write (an explicit write and the value an
  anchor or mock publishes share one storage, so the nearer one wins), the
  container's size class, then the platform default.
• SceneGeometry: a per-scene @Observable, read with
  @Environment(SceneGeometry.self). It exposes size, safeAreaInsets,
  horizontalSizeClass, verticalSizeClass, isLandscapeAspectRatio,
  interfaceOrientation (unavailable on native macOS), hinge, hingeStatus,
  and reservedRegions(kind:options:in:). It is never nil under an anchor
  and updates in place. @Environment(SceneGeometry.self) private var scene: SceneGeometry? is the optional form for shared components that can't
  guarantee an anchor. safeAreaInsets follow the layout direction: in a
  right-to-left layout, leading is the physical right edge.
• sceneGeometryAnchor(): installs SceneGeometry at the scene root. It
  discovers the UIWindowScene (iOS, visionOS, Catalyst) or NSWindow
  (macOS), and also publishes the 0.4 \.sceneLayout value so old and new
  code share one anchor.
• iPhone Duo and hinge support on iOS 27.1 and later: the Responsive
  namespace mirrors Apple's DeviceHinge and ReservedRegion as
  Responsive.DeviceHinge and Responsive.ReservedRegion, so the same code
  compiles on iOS 26. hinge is nil on devices without one, on iOS 26, and
  on external displays. The anchor reports the hinge's pose from launch.
• readableContentWidth(_:): caps scroll content at a fraction of the scene
  width (default 0.66) on regular widths. Across a vertical fold it lifts the
  cap so content spans both halves; configure this with
  readableContentWidthDivisionBehavior(_:) and
  ReadableContentWidthDivisionBehavior (.automatic, .expand, .ignore).
• SceneGeometry.Mock, sceneGeometry(mocking:), and the
  .sceneGeometry(mocking:) preview trait. Mocks set the scene geometry and
  both Apple and scene size classes, and take a hinge and reserved regions in
  scene coordinates. Presets: .phone(_:), .pad(_:), .foldablePhone(_:)
  (iPhone Duo poses .closed, .open(.tall/.wide),
  .partiallyOpen(.book/.laptop)), .mac(size:), and .vision. Foldable
  numbers are measured in the Xcode 27.2 Device Hub simulator.
• DocC articles: Designing for Every Form Factor, Scene Geometry, Previews
  and Testing, and Migrating from Phone and Tablet Layouts.
• Demo app is multiplatform (iOS, macOS, visionOS), with fold,
  readable-width, and preset gallery pages.

Changed

• accessibilityScrollView(_:) and accessibilityScrollFloor(_:) keep their
  API, now read the window height from SceneGeometry, and work on every
  platform.
• Building requires Xcode 27.2 or later.
• README, DocC landing page, and the bundled Claude Code skill
  (responsivelayoutkit) are rewritten for the 0.5 API, with references for
  iPhone Duo poses and migration. Plugin bumped to 2.0.0.
• CI runs on xcode-27 runners with a multiplatform matrix: tests on macOS
  and the iPhone simulator, builds for visionOS and Mac Catalyst. The iPad
  simulator job is dropped.

Deprecated

Every 0.4 API is deprecated, keeps its 0.4.0 behavior, never gains iPhone Duo
behavior, and will be removed in 1.0. The 0.4 APIs are available only on iOS,
iPadOS, and Mac Catalyst, where 0.4 ran.

• ResponsiveLayout, value(phone:tablet:), and the layout ratios: use
  UserInterfaceSizeClass and value(compact:regular:).
• LayoutContext: use \.horizontalSizeClass (container) or
  \.sceneHorizontalSizeClass (scene).
• ResponsiveView(in:phone:tablet:) and .responsive(in:content:): read the
  size class from the environment and branch or apply modifiers directly.
• .responsiveLayout(_:) and \.responsiveLayoutOverride: use
  .environment(\.sceneHorizontalSizeClass, …), or \.horizontalSizeClass
  when system containers should change too.
• \.containerResponsiveLayout: use \.horizontalSizeClass.
• \.responsiveLayout: use \.sceneHorizontalSizeClass.
• \.sceneLayout, SceneLayoutEnvironment, and SceneLayoutReader: use
  @Environment(SceneGeometry.self).
• .sceneLayoutAnchor(): renamed to sceneGeometryAnchor() (Xcode offers a
  fix-it).
• SceneLayoutMockValues and .sceneLayout(mocking:): use
  SceneGeometry.Mock and sceneGeometry(mocking:).
• .responsiveContentWidth(tabletFraction:): use readableContentWidth(_:),
  which differs only across a vertical fold on iPhone Duo.