Prevent stale host visibility thrash after tab move

Sources/GhosttyTerminalView.swift

@@ -5061,6 +5061,16 @@ struct GhosttyTerminalView: NSViewRepresentable {
         Coordinator()
     }
 
+    static func shouldApplyImmediateHostedStateUpdate(
+        hostWindowAttached: Bool,
+        hostedViewHasSuperview: Bool,
+        isBoundToCurrentHost: Bool
+    ) -> Bool {
+        if !hostWindowAttached { return true }
+        if isBoundToCurrentHost { return true }
+        return !hostedViewHasSuperview
+    }
+
     func makeNSView(context: Context) -> NSView {
         let container = HostContainerView()
         container.wantsLayer = false
@@ -5103,8 +5113,6 @@ struct GhosttyTerminalView: NSViewRepresentable {
 
         // Keep the surface lifecycle and handlers updated even if we defer re-parenting.
         hostedView.attachSurface(terminalSurface)
-        hostedView.setVisibleInUI(isVisibleInUI)
-        hostedView.setActive(isActive)
         hostedView.setInactiveOverlay(
             color: inactiveOverlayColor,
             opacity: CGFloat(inactiveOverlayOpacity),
@@ -5139,7 +5147,8 @@ struct GhosttyTerminalView: NSViewRepresentable {
         coordinator.attachGeneration += 1
         let generation = coordinator.attachGeneration
 
-        if let host = nsView as? HostContainerView {
+        let hostContainer = nsView as? HostContainerView
+        if let host = hostContainer {
             host.onDidMoveToWindow = { [weak host, weak hostedView, weak coordinator] in
                 guard let host, let hostedView, let coordinator else { return }
                 guard coordinator.attachGeneration == generation else { return }
@@ -5190,6 +5199,28 @@ struct GhosttyTerminalView: NSViewRepresentable {
                 )
             }
         }
+
+        let hostWindowAttached = hostContainer?.window != nil
+        let isBoundToCurrentHost = hostContainer.map { host in
+            TerminalWindowPortalRegistry.isHostedView(hostedView, boundTo: host)
+        } ?? true
+        let shouldApplyImmediateHostedState = Self.shouldApplyImmediateHostedStateUpdate(
+            hostWindowAttached: hostWindowAttached,
+            hostedViewHasSuperview: hostedView.superview != nil,
+            isBoundToCurrentHost: isBoundToCurrentHost
+        )
+
+        if shouldApplyImmediateHostedState {
+            hostedView.setVisibleInUI(isVisibleInUI)
+            hostedView.setActive(isActive)
+        } else {
+            // Preserve portal entry visibility while a stale host is still receiving SwiftUI updates.
+            // The currently bound host remains authoritative for immediate visible/active state.
+            TerminalWindowPortalRegistry.updateEntryVisibility(
+                for: hostedView,
+                visibleInUI: isVisibleInUI
+            )
+        }
     }
 
     static func dismantleNSView(_ nsView: NSView, coordinator: Coordinator) {

Sources/TerminalWindowPortal.swift

@@ -934,6 +934,12 @@ final class WindowTerminalPortal: NSObject {
         entriesByHostedId[hostedId] = entry
     }
 
+    func isHostedViewBoundToAnchor(withId hostedId: ObjectIdentifier, anchorView: NSView) -> Bool {
+        guard let entry = entriesByHostedId[hostedId],
+              let boundAnchor = entry.anchorView else { return false }
+        return boundAnchor === anchorView
+    }
+
     func bind(hostedView: GhosttySurfaceScrollView, to anchorView: NSView, visibleInUI: Bool, zPriority: Int = 0) {
         guard ensureInstalled() else { return }
 
@@ -1462,6 +1468,15 @@ enum TerminalWindowPortalRegistry {
         portal.updateEntryVisibility(forHostedId: hostedId, visibleInUI: visibleInUI)
     }
 
+    static func isHostedView(_ hostedView: GhosttySurfaceScrollView, boundTo anchorView: NSView) -> Bool {
+        let hostedId = ObjectIdentifier(hostedView)
+        guard let window = anchorView.window else { return false }
+        let windowId = ObjectIdentifier(window)
+        guard hostedToWindowId[hostedId] == windowId,
+              let portal = portalsByWindowId[windowId] else { return false }
+        return portal.isHostedViewBoundToAnchor(withId: hostedId, anchorView: anchorView)
+    }
+
     static func viewAtWindowPoint(_ windowPoint: NSPoint, in window: NSWindow) -> NSView? {
         let portal = portal(for: window)
         return portal.viewAtWindowPoint(windowPoint)

cmuxTests/CmuxWebViewKeyEquivalentTests.swift

@@ -6289,3 +6289,45 @@ final class BrowserOmnibarFocusPolicyTests: XCTestCase {
         )
     }
 }
+
+final class GhosttyTerminalViewVisibilityPolicyTests: XCTestCase {
+    func testImmediateStateUpdateAllowedWhenHostNotInWindow() {
+        XCTAssertTrue(
+            GhosttyTerminalView.shouldApplyImmediateHostedStateUpdate(
+                hostWindowAttached: false,
+                hostedViewHasSuperview: true,
+                isBoundToCurrentHost: false
+            )
+        )
+    }
+
+    func testImmediateStateUpdateAllowedWhenBoundToCurrentHost() {
+        XCTAssertTrue(
+            GhosttyTerminalView.shouldApplyImmediateHostedStateUpdate(
+                hostWindowAttached: true,
+                hostedViewHasSuperview: true,
+                isBoundToCurrentHost: true
+            )
+        )
+    }
+
+    func testImmediateStateUpdateSkippedForStaleHostBoundElsewhere() {
+        XCTAssertFalse(
+            GhosttyTerminalView.shouldApplyImmediateHostedStateUpdate(
+                hostWindowAttached: true,
+                hostedViewHasSuperview: true,
+                isBoundToCurrentHost: false
+            )
+        )
+    }
+
+    func testImmediateStateUpdateAllowedWhenUnboundAndNotAttachedAnywhere() {
+        XCTAssertTrue(
+            GhosttyTerminalView.shouldApplyImmediateHostedStateUpdate(
+                hostWindowAttached: true,
+                hostedViewHasSuperview: false,
+                isBoundToCurrentHost: false
+            )
+        )
+    }
+}