Polish sidebar transitions and search dismissal

Sources/MeridianCore/Stores/BrowserStore.swift

@@ -730,15 +730,12 @@ public final class BrowserStore: ObservableObject {
         guard let space = spaces.first(where: { $0.id == id }) else {
             return
         }
-        let shouldPreserveCommandBar = isCommandBarPresented && commandBarMode == .newTab
         selectedSpaceID = id
         selectedTabID = space.selectedTabID
             ?? space.favoriteTabIDs.first
             ?? space.pinnedTabIDs.first
             ?? space.regularTabIDs.first
-        if !shouldPreserveCommandBar {
-            hideCommandBar()
-        }
+        hideCommandBar()
         refreshActivePageSecurityStatus()
         schedulePersistSession()
     }
@@ -780,6 +777,7 @@ public final class BrowserStore: ObservableObject {
         updateTab(id) { tab in
             tab.lastActiveDate = Date()
         }
+        hideCommandBar()
         refreshActivePageSecurityStatus()
         persistSession()
     }

Sources/MeridianCore/Views/Sidebar/SidebarSpacePagerPolicy.swift

@@ -18,6 +18,37 @@ enum SidebarSpacePagerMetrics {
     static let creationReturnAnimation: Animation = .smooth(duration: 0.24, extraBounce: 0.08)
 }
 
+struct SidebarSpacePagerPageTransitionPresentation: Equatable, Sendable {
+    let opacity: Double
+    let scale: CGFloat
+    let verticalOffset: CGFloat
+}
+
+enum SidebarSpacePagerPageTransition {
+    /// A compositor-only emphasis curve for page contents. Foregrounds remain
+    /// contrast-correct for their own themes, while the outgoing page recedes
+    /// and the incoming page resolves without publishing scroll geometry.
+    static func presentation(
+        forPhaseValue phaseValue: Double
+    ) -> SidebarSpacePagerPageTransitionPresentation {
+        guard phaseValue.isFinite else {
+            return SidebarSpacePagerPageTransitionPresentation(
+                opacity: 1,
+                scale: 1,
+                verticalOffset: 0
+            )
+        }
+
+        let distance = min(abs(phaseValue), 1)
+        let easedDistance = distance * distance * (3 - 2 * distance)
+        return SidebarSpacePagerPageTransitionPresentation(
+            opacity: 1 - 0.42 * easedDistance,
+            scale: CGFloat(1 - 0.012 * easedDistance),
+            verticalOffset: CGFloat(2.5 * easedDistance)
+        )
+    }
+}
+
 enum SidebarSpacePagerHorizontalIntent: Equatable, Sendable {
     case backward
     case forward

Sources/MeridianCore/Views/Sidebar/SidebarView.swift

@@ -371,6 +371,17 @@ public struct SidebarView: View {
             }
             .accessibilityHidden(true)
         }
+        .simultaneousGesture(sidebarInteractionGesture)
+    }
+
+    private var sidebarInteractionGesture: some Gesture {
+        DragGesture(minimumDistance: 0)
+            .onChanged { _ in
+                guard store.isCommandBarPresented else {
+                    return
+                }
+                store.hideCommandBar()
+            }
     }
 
     private var browserControlsHeader: some View {
@@ -2898,6 +2909,27 @@ private struct WindowReader: NSViewRepresentable {
     }
 }
 
+private func sidebarSpacePagerPageTransitionEffect(
+    _ content: EmptyVisualEffect,
+    phase: ScrollTransitionPhase
+) -> some VisualEffect {
+    let presentation = SidebarSpacePagerPageTransition.presentation(
+        forPhaseValue: phase.value
+    )
+    return content
+        .opacity(presentation.opacity)
+        .scaleEffect(presentation.scale)
+        .offset(y: presentation.verticalOffset)
+}
+
+private struct SidebarSpacePagerPageTransitionModifier: ViewModifier {
+    func body(content: Content) -> some View {
+        content.scrollTransition(.interactive, axis: .horizontal) { content, phase in
+            sidebarSpacePagerPageTransitionEffect(content, phase: phase)
+        }
+    }
+}
+
 private struct SidebarSpacePagerView: View {
     let snapshot: SidebarSpacePagerSnapshot
     let navigationRequest: SidebarSpacePagerNavigationRequest?
@@ -2959,6 +2991,7 @@ private struct SidebarSpacePagerView: View {
                         pageView(page)
                         .id(page.id)
                         .frame(width: pageWidth, height: proxy.size.height, alignment: .top)
+                        .modifier(SidebarSpacePagerPageTransitionModifier())
                         // Once horizontal paging owns the gesture, tab rows no
                         // longer participate in hit testing until the pager is idle.
                         .allowsHitTesting(!scrollIsActive)

Tests/MeridianBrowserTests/BrowserStoreTests.swift

@@ -589,7 +589,7 @@ final class BrowserStoreTests: XCTestCase {
         XCTAssertEqual(store.commandBarFocusRequest, previousFocusRequest + 2)
     }
 
-    func testSelectingSpacePreservesNewTabCommandBar() throws {
+    func testSelectingSpaceClosesNewTabCommandBar() throws {
         let store = BrowserStore()
         let initialSpaceID = try XCTUnwrap(store.selectedSpaceID)
         let targetSpace = store.createSpace(name: "Work")
@@ -599,23 +599,17 @@ final class BrowserStoreTests: XCTestCase {
         store.selectSpace(targetSpace.id)
 
         XCTAssertEqual(store.selectedSpaceID, targetSpace.id)
-        XCTAssertTrue(store.isCommandBarPresented)
-        XCTAssertEqual(store.commandBarMode, .newTab)
+        XCTAssertFalse(store.isCommandBarPresented)
+        XCTAssertEqual(store.commandBarMode, .address)
     }
 
-    func testNewTabCommandBarSubmissionUsesSelectedTargetSpaceAfterSwitching() throws {
+    func testSelectingTabClosesNewTabCommandBar() throws {
         let store = BrowserStore()
-        let initialSpaceID = try XCTUnwrap(store.selectedSpaceID)
-        let targetSpace = store.createSpace(name: "Work")
-        store.selectSpace(initialSpaceID)
+        let selectedTabID = try XCTUnwrap(store.selectedTabID)
 
         store.beginNewTab()
-        store.selectSpace(targetSpace.id)
-        store.submitAddressInput("example.com")
+        store.selectTab(selectedTabID)
 
-        let activeTab = try XCTUnwrap(store.activeTab)
-        XCTAssertEqual(activeTab.parentSpaceID, targetSpace.id)
-        XCTAssertTrue(store.selectedSpace?.regularTabIDs.contains(activeTab.id) ?? false)
         XCTAssertFalse(store.isCommandBarPresented)
         XCTAssertEqual(store.commandBarMode, .address)
     }

Tests/MeridianBrowserTests/SidebarSpacePagerSelectionTests.swift

@@ -14,6 +14,44 @@ private final class SidebarAddressMorphRendererSpy: SidebarAddressMorphRendering
 }
 
 final class SidebarSpacePagerSelectionTests: XCTestCase {
+    func testPageTransitionKeepsSettledPageExact() {
+        XCTAssertEqual(
+            SidebarSpacePagerPageTransition.presentation(forPhaseValue: 0),
+            SidebarSpacePagerPageTransitionPresentation(
+                opacity: 1,
+                scale: 1,
+                verticalOffset: 0
+            )
+        )
+        XCTAssertEqual(
+            SidebarSpacePagerPageTransition.presentation(forPhaseValue: .nan),
+            SidebarSpacePagerPageTransitionPresentation(
+                opacity: 1,
+                scale: 1,
+                verticalOffset: 0
+            )
+        )
+    }
+
+    func testPageTransitionCrossfadesSymmetricallyWithoutHidingPages() {
+        let leading = SidebarSpacePagerPageTransition.presentation(
+            forPhaseValue: -0.5
+        )
+        let trailing = SidebarSpacePagerPageTransition.presentation(
+            forPhaseValue: 0.5
+        )
+        let edge = SidebarSpacePagerPageTransition.presentation(
+            forPhaseValue: 1
+        )
+
+        XCTAssertEqual(leading, trailing)
+        XCTAssertEqual(leading.opacity, 0.79, accuracy: 0.0001)
+        XCTAssertEqual(leading.scale, 0.994, accuracy: 0.0001)
+        XCTAssertEqual(leading.verticalOffset, 1.25, accuracy: 0.0001)
+        XCTAssertEqual(edge.opacity, 0.58, accuracy: 0.0001)
+        XCTAssertGreaterThan(edge.opacity, 0.5)
+    }
+
     func testSpaceDragPayloadRoundTripsSpaceID() {
         let spaceID = UUID()