From ddf31591c970eec458e3fb7ea7fb5d7f32599dea Mon Sep 17 00:00:00 2001
From: defia <defiaq@gmail.com>
Date: Mon, 20 Jul 2026 18:17:07 +0800
Subject: [PATCH] fix: prevent stale surface repins after workspace switches

---
 Glint/Pane/PaneSurfaceRepresentable.swift   | 22 ++++++++++++++++++---
 Glint/Pane/PaneView.swift                   |  7 ++++++-
 GlintTests/PerformanceRegressionTests.swift | 13 ++++++++++++
 3 files changed, 38 insertions(+), 4 deletions(-)

diff --git a/Glint/Pane/PaneSurfaceRepresentable.swift b/Glint/Pane/PaneSurfaceRepresentable.swift
index 0e82bc6..183e392 100644
--- a/Glint/Pane/PaneSurfaceRepresentable.swift
+++ b/Glint/Pane/PaneSurfaceRepresentable.swift
@@ -1,6 +1,14 @@
 import SwiftUI
 import AppKit
 
+enum SurfaceReassertionPolicy {
+    static func shouldReassert(containerIsAttached: Bool,
+                               expectedSurfaceMatches: Bool,
+                               paneIsVisible: Bool) -> Bool {
+        containerIsAttached && expectedSurfaceMatches && paneIsVisible
+    }
+}
+
 /// Hosts a stable, store-owned `GhosttySurfaceView` inside a fresh container
 /// NSView. SwiftUI may rebuild the container any time the split tree reshapes;
 /// the surface itself outlives that and just re-parents.
@@ -15,6 +23,9 @@ struct PaneSurfaceRepresentable: NSViewRepresentable {
     /// updateNSView re-runs ~1/s, and re-grabbing the terminal surface here
     /// races the palette's search field and yanks focus back off it.
     let deferFocus: Bool
+    /// Evaluated inside the deferred re-pin, not when SwiftUI builds the view:
+    /// workspace/tab selection may change before that callback runs.
+    let isPaneVisible: () -> Bool
 
     func makeNSView(context: Context) -> NoDragContainerView {
         let container = NoDragContainerView()
@@ -131,10 +142,15 @@ struct PaneSurfaceRepresentable: NSViewRepresentable {
         // re-parenting the surface into a container that's torn down moments
         // later, leaving the live pane blank. Containers that survive the
         // commit re-assert their claim right after it; dismantled ones are out
-        // of the window by then and bail.
+        // of the window by then and bail. A recycled container can still be in
+        // the window after a workspace/tab switch, so also verify that this
+        // surface's pane is the one currently visible.
         DispatchQueue.main.async {
-            guard container.window != nil,
-                  container.expectedSurface === surface else { return }
+            guard SurfaceReassertionPolicy.shouldReassert(
+                containerIsAttached: container.window != nil,
+                expectedSurfaceMatches: container.expectedSurface === surface,
+                paneIsVisible: isPaneVisible()
+            ) else { return }
             Self.pin(surface, in: container)
         }
     }
diff --git a/Glint/Pane/PaneView.swift b/Glint/Pane/PaneView.swift
index 36aa12d..30ef3bb 100644
--- a/Glint/Pane/PaneView.swift
+++ b/Glint/Pane/PaneView.swift
@@ -57,7 +57,12 @@ struct PaneView: View {
             PaneSurfaceRepresentable(
                 surfaceView: store.surfaceView(workspaceID: workspaceID, paneID: paneID, cwd: cwd),
                 focused: isFocused,
-                deferFocus: store.commandPaletteOpen || store.agentChooserIntent != nil
+                deferFocus: store.commandPaletteOpen || store.agentChooserIntent != nil,
+                isPaneVisible: {
+                    guard store.selectedWorkspaceID == workspaceID,
+                          let tab = store.selectedWorkspace?.selectedTab else { return false }
+                    return tab.root.leaves.contains(paneID)
+                }
             )
             if !isFocused {
                 // Use a black wash so translucent panes stay translucent; tune
diff --git a/GlintTests/PerformanceRegressionTests.swift b/GlintTests/PerformanceRegressionTests.swift
index 5f01f8f..ec2f35d 100644
--- a/GlintTests/PerformanceRegressionTests.swift
+++ b/GlintTests/PerformanceRegressionTests.swift
@@ -145,6 +145,19 @@ final class PerformanceRegressionTests: XCTestCase {
         ))
     }
 
+    func testDelayedSurfaceReassertRejectsPaneAfterWorkspaceSwitch() {
+        XCTAssertTrue(SurfaceReassertionPolicy.shouldReassert(
+            containerIsAttached: true,
+            expectedSurfaceMatches: true,
+            paneIsVisible: true
+        ))
+        XCTAssertFalse(SurfaceReassertionPolicy.shouldReassert(
+            containerIsAttached: true,
+            expectedSurfaceMatches: true,
+            paneIsVisible: false
+        ))
+    }
+
     func testBackgroundWorkspaceFirstResponderDoesNotPauseIdleClock() {
         XCTAssertTrue(TerminalFocusPolicy.protectsFromIdleOfflining(
             appIsActive: true,