feat(ipad): W1-W3 — adaptive split-view layout + finding fixes

T-iPad-2: AdaptiveRootView/LayoutPolicy (sole size-class decision), SplitRootView
(NavigationSplitView sidebar+detail), StackRootView (iPhone path verbatim, zero
regression); privacy shade hoisted to shared ZStack top for both branches
T-iPad-3: KeyBarVisibility predicate (hide when hardware keyboard present),
pointer context menu (copy/new-in-cwd/kill, all via existing channels)
T-iPad-4: Projects multi-column grid on iPad (idiom-gated), adaptive sheet detents
T-iPad-5 findings (4/4 fixed): kill onKillSession thread-through +
AppCoordinator.killCurrentSession; split route-gated to .sessions (iPad first-run
pairing); continue-last banner in split sidebar; iPad XCUITest deferred (covered
by SidebarSelectionTests)
Verified: iPhone 16 277 + iPad Pro 11 278 tests green; packages 261 + integration 10;
zero changes under ios/Packages, src/, public/

ios/App/WebTerm/Wiring/RootView.swift

@@ -1,62 +1,39 @@
 import HostRegistry
 import SwiftUI
 
-/// T-iOS-15 · Root of the app: route switch (Pairing / SessionList), terminal
-/// push, add-host sheet, scenePhase forwarding and the privacy shade.
+/// T-iOS-15 / T-iPad-2 · App 根入口。历史上这里是单一 `NavigationStack` +
+/// 隐私遮罩 + sheets/scenePhase/deepLink 的全部布线；iPad 自适应（T-iPad-2）
+/// 把它拆成两层：
+/// - `RootView`（本 struct）保持 `@main` 的唯一实例化点不变（WebTermApp 仍
+///   `RootView(coordinator:)`），内部只委托给 `AdaptiveRootView`。
+/// - `AdaptiveRootView` 按 `horizontalSizeClass` 选 `StackRootView`（compact，
+///   现有路径，字节级不变）或 `SplitRootView`（regular，iPad 分栏），并把
+///   隐私遮罩 / scenePhase / deepLink / sheets 这些**设备无关的横切布线**
+///   上提到唯一一处，两分支共享（遮罩因此仍是两分支共同的 ZStack 顶层）。
 ///
-/// The shade is the TOPMOST layer of this ZStack and appears whenever
-/// `scenePhase != .active` (exact rule — PrivacyShadePolicy + tests); it
-/// covers the whole navigation tree, terminal included. Sheets live above any
-/// overlay, but no sheet renders terminal bytes (pairing / plan gate only).
+/// `StackRootView` 是原 `RootView` 的 body **原样搬迁** —— compact 分支复用它
+/// 不改一行，故 iPhone 逐屏渲染与适配前一致（零回归硬性要求）。
 struct RootView: View {
     @Bindable var coordinator: AppCoordinator
-    @Environment(\.scenePhase) private var scenePhase
 
     var body: some View {
-        ZStack {
-            NavigationStack {
-                rootContent
-                    .navigationDestination(isPresented: terminalBinding) {
-                        terminalDestination
-                    }
-            }
-            if PrivacyShadePolicy.isShadeVisible(for: scenePhase) {
-                PrivacyShadeView()
-            }
-        }
-        .task { await coordinator.bootstrap() }
-        .onChange(of: scenePhase) { _, phase in
-            coordinator.handleScenePhase(phase)
-        }
-        .onOpenURL { coordinator.handleDeepLink(url: $0) } // T-iOS-22
-        .alert(DeepLinkCopy.hintTitle, isPresented: deepLinkHintBinding) {
-            Button(DeepLinkCopy.hintConfirm) { coordinator.deepLink.clearHint() }
-        } message: {
-            Text(coordinator.deepLink.hintMessage ?? "")
-        }
-        .sheet(
-            isPresented: $coordinator.isAddHostPresented,
-            onDismiss: { coordinator.addHostDismissed() }
-        ) {
-            addHostSheet
-        }
-        .sheet(
-            isPresented: $coordinator.isProjectsPresented,
-            onDismiss: { coordinator.projectsDismissed() }
-        ) {
-            projectsSheet
-        }
+        AdaptiveRootView(coordinator: coordinator)
     }
+}
 
-    /// Deep-link hint alert (unknown host / store failure, T-iOS-22).
-    private var deepLinkHintBinding: Binding<Bool> {
-        Binding(
-            get: { coordinator.deepLink.hintMessage != nil },
-            set: { presented in
-                guard !presented else { return }
-                coordinator.deepLink.clearHint()
-            }
-        )
+/// T-iPad-2 · compact 宽度（iPhone / iPad Slide Over）的根视图 —— 原
+/// `RootView` 的 `NavigationStack` 主体原样搬迁，行为字节级不变。横切布线
+/// （遮罩/scenePhase/deepLink/sheets）不在这里，已上提到 `AdaptiveRootView`。
+struct StackRootView: View {
+    @Bindable var coordinator: AppCoordinator
+
+    var body: some View {
+        NavigationStack {
+            rootContent
+                .navigationDestination(isPresented: terminalBinding) {
+                    terminalDestination
+                }
+        }
     }
 
     // MARK: - Route switch
@@ -140,7 +117,8 @@ struct RootView: View {
         if let controller = coordinator.terminalController {
             TerminalContainerView(
                 controller: controller,
-                onNewSessionInCwd: { coordinator.openNewSessionInCurrentCwd() }
+                onNewSessionInCwd: { coordinator.openNewSessionInCurrentCwd() },
+                onKillSession: { coordinator.killCurrentSession() } // T-iPad-3
             )
             // T-iOS-29 · identity PER CONTROLLER: an in-place session switch
             // (new-in-cwd, deep link) swaps the controller while the
@@ -151,40 +129,15 @@ struct RootView: View {
             .id(controller.id)
         }
     }
-
-    // MARK: - Add-host sheet (multi-host entry, list header)
-
-    @ViewBuilder private var addHostSheet: some View {
-        if let viewModel = coordinator.addHostPairingViewModel {
-            NavigationStack {
-                PairingScreen(viewModel: viewModel) { host in
-                    coordinator.completeAddHost(host)
-                }
-            }
-        }
-    }
-
-    // MARK: - Projects sheet (T-iOS-26)
-
-    /// 自带 NavigationStack：列表 → 详情 → 差异都在 sheet 内 push；
-    /// "在此仓库开新会话" 关掉 sheet 并在根导航推入终端。
-    @ViewBuilder private var projectsSheet: some View {
-        if let viewModel = coordinator.projectsViewModel {
-            NavigationStack {
-                ProjectsScreen(viewModel: viewModel) { request in
-                    coordinator.openProject(request)
-                }
-            }
-        }
-    }
 }
 
-private enum RootMetrics {
+enum RootMetrics {
     static let bannerHorizontalPadding: CGFloat = 16
     static let bannerVerticalPadding: CGFloat = 8
 }
 
-private enum RootCopy {
+/// 根层用户可见文案（internal —— `SplitRootView` 复用同一「项目」标签，DRY）。
+enum RootCopy {
     static let continueLast = "继续上次会话"
     static let projects = "项目"
 }