From c28317a766e61fe3846c58681c97d1b0b29c772c Mon Sep 17 00:00:00 2001
From: Kyle <kyle201817146@gmail.com>
Date: Mon, 19 Oct 2026 15:39:13 +0800
Subject: [PATCH 1/2] fix: preserve content when applying transitions

---
 .../Animation/Transition/Transition.swift     |  8 ++-
 .../Transition/TransitionTests.swift          | 65 +++++++++++++++++++
 2 files changed, 71 insertions(+), 2 deletions(-)
 create mode 100644 Tests/OpenSwiftUICoreTests/Animation/Transition/TransitionTests.swift

diff --git a/Sources/OpenSwiftUICore/Animation/Transition/Transition.swift b/Sources/OpenSwiftUICore/Animation/Transition/Transition.swift
index 586931d84..6828c6b20 100644
--- a/Sources/OpenSwiftUICore/Animation/Transition/Transition.swift
+++ b/Sources/OpenSwiftUICore/Animation/Transition/Transition.swift
@@ -153,10 +153,14 @@ package struct ApplyTransitionModifier<TransitionType>: PrimitiveViewModifier, M
         inputs: _ViewInputs,
         body: @escaping (_Graph, _ViewInputs) -> _ViewOutputs
     ) -> _ViewOutputs {
-        .init()
+        TransitionType.makeView(
+            view: _GraphValue(Child(modifier: modifier.value)),
+            inputs: inputs,
+            body: body
+        )
     }
 
-    nonisolated package static func _viewListCount(
+    nonisolated package static func viewListCount(
         inputs: _ViewListCountInputs,
         body: (_ViewListCountInputs) -> Int?
     ) -> Int? {
diff --git a/Tests/OpenSwiftUICoreTests/Animation/Transition/TransitionTests.swift b/Tests/OpenSwiftUICoreTests/Animation/Transition/TransitionTests.swift
new file mode 100644
index 000000000..9d4152f9d
--- /dev/null
+++ b/Tests/OpenSwiftUICoreTests/Animation/Transition/TransitionTests.swift
@@ -0,0 +1,65 @@
+//
+//  TransitionTests.swift
+//  OpenSwiftUICoreTests
+
+import Foundation
+import OpenAttributeGraphShims
+@_spi(ForOpenSwiftUIOnly) @testable import OpenSwiftUICore
+import Testing
+
+@MainActor
+@Suite(.disabled(if: attributeGraphVendor == .oag))
+struct TransitionTests {
+    @Test
+    func viewListCountWitnessPreservesBodyCount() {
+        var bodyCalls = 0
+        let count = viewListCount(
+            ApplyTransitionModifier<IdentityTransition>.self,
+            inputs: _ViewListCountInputs(.init(.invalid))
+        ) { _ in
+            bodyCalls += 1
+            return 2
+        }
+        #expect(count == 2)
+        #expect(bodyCalls == 1)
+    }
+
+    @Test(arguments: [TransitionPhase.willAppear, .identity, .didDisappear])
+    func combinedTransitionPreservesContentLayout(phase: TransitionPhase) {
+        checkLayout(
+            transition: MoveTransition(edge: .leading).combined(with: .opacity),
+            phase: phase
+        )
+    }
+
+    @Test(arguments: [TransitionPhase.willAppear, .identity, .didDisappear])
+    func asymmetricTransitionPreservesContentLayout(phase: TransitionPhase) {
+        checkLayout(
+            transition: AsymmetricTransition(
+                insertion: MoveTransition(edge: .leading).combined(with: .opacity),
+                removal: OpacityTransition()
+            ),
+            phase: phase
+        )
+    }
+
+    private func checkLayout<T: Transition>(transition: T, phase: TransitionPhase) {
+        let content = Color.red
+            .frame(width: 32, height: 48)
+            .modifier(ApplyTransitionModifier(transition: transition, phase: phase))
+        Update.perform {
+            let graph = ViewGraph(rootViewType: type(of: content), requestedOutputs: .layout)
+            defer { graph.invalidate() }
+            graph.setRootView(content)
+            #expect(graph.sizeThatFits(.unspecified) == CGSize(width: 32, height: 48))
+        }
+    }
+
+    private func viewListCount<M: ViewModifier>(
+        _ modifier: M.Type,
+        inputs: _ViewListCountInputs,
+        body: (_ViewListCountInputs) -> Int?
+    ) -> Int? {
+        M._viewListCount(inputs: inputs, body: body)
+    }
+}

From e223e7b9267706e4396e9574da5865a6d09e3901 Mon Sep 17 00:00:00 2001
From: Kyle <kyle201817146@gmail.com>
Date: Mon, 19 Oct 2026 23:15:15 +0800
Subject: [PATCH 2/2] test: tag transition regression tests as aigc

---
 .../Animation/Transition/TransitionTests.swift                 | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/Tests/OpenSwiftUICoreTests/Animation/Transition/TransitionTests.swift b/Tests/OpenSwiftUICoreTests/Animation/Transition/TransitionTests.swift
index 9d4152f9d..5f43a1170 100644
--- a/Tests/OpenSwiftUICoreTests/Animation/Transition/TransitionTests.swift
+++ b/Tests/OpenSwiftUICoreTests/Animation/Transition/TransitionTests.swift
@@ -5,10 +5,11 @@
 import Foundation
 import OpenAttributeGraphShims
 @_spi(ForOpenSwiftUIOnly) @testable import OpenSwiftUICore
+import OpenSwiftUITestsSupport
 import Testing
 
 @MainActor
-@Suite(.disabled(if: attributeGraphVendor == .oag))
+@Suite(.tags(.aigc), .disabled(if: attributeGraphVendor == .oag))
 struct TransitionTests {
     @Test
     func viewListCountWitnessPreservesBodyCount() {