Fix AdaptiveTrigger memory leak when VisualStateGroups are replaced after attach

[Shalini-Ashokan]

Note

Are you waiting for the changes in this PR to be merged?
It would be very helpful if you could test the resulting artifacts from this PR and let us know in a comment if this change resolves your issue. Thank you!

Issue Details

AdaptiveTrigger leaks memory when VisualStateGroups are replaced at runtime on a visible element. This causes entire view models (data) to stay in memory permanently even after navigation, growing by ~3 MB per page visit.

Root Cause

In VisualStateGroupsPropertyChanged, detach triggers from the old VisualStateGroups before unapplying old setters and clearing the old VisualElement association. This unsubscribes old AdaptiveTrigger instances from Window.SizeChanged when VisualStateGroups are replaced after the element is already attached.

Description of Change

In VisualStateGroupsPropertyChanged, detach triggers from the old VisualStateGroups before unapplying old setters and clearing the old VisualElement association. This unsubscribes old AdaptiveTrigger instances from Window.SizeChanged when VisualStateGroups are replaced after the element is already attached.

After assigning the new VisualStateGroups, if the element is already in a Window, call visualElement.InvalidateStateTriggers(true) so the new triggers attach and activate immediately instead of waiting for a future Window change.

AdaptiveTrigger now stores its associated VisualElement through a WeakReference while attached. This avoids a strong AdaptiveTrigger -> VisualElement retention path if a detach path is missed.

Validated the behavior in the following platforms

• Android
• Windows
• iOS
• Mac

Issues Fixed

Fixes #36032

Output ScreenShot

Before	After

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AI Review Summary

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🗂️ Review Sessions — click to expand

🚦 Gate — Test Before & After Fix

Gate Result: ✅ PASSED

Platform: ANDROID · Base: main · Merge base: 6e107357

Test	Without Fix (expect FAIL)	With Fix (expect PASS)
🧪 AdaptiveTriggerTests AdaptiveTriggerTests	✅ FAIL — 108s	✅ PASS — 68s

🔴 Without fix — 🧪 AdaptiveTriggerTests: FAIL ✅ · 108s

  Determining projects to restore...
  Restored /home/vsts/work/1/s/src/Controls/tests/Core.UnitTests/Controls.Core.UnitTests.csproj (in 5.47 sec).
  Restored /home/vsts/work/1/s/src/Controls/src/Xaml/Controls.Xaml.csproj (in 9.17 sec).
  Restored /home/vsts/work/1/s/src/Controls/src/Core/Controls.Core.csproj (in 3.06 sec).
  Restored /home/vsts/work/1/s/src/TestUtils/src/TestUtils/TestUtils.csproj (in 7 ms).
  Restored /home/vsts/work/1/s/src/Graphics/src/Graphics/Graphics.csproj (in 10 ms).
  Restored /home/vsts/work/1/s/src/Essentials/src/Essentials.csproj (in 20 ms).
  Restored /home/vsts/work/1/s/src/Core/src/Core.csproj (in 51 ms).
  Restored /home/vsts/work/1/s/src/Core/maps/src/Maps.csproj (in 1.71 sec).
  Restored /home/vsts/work/1/s/src/Controls/Maps/src/Controls.Maps.csproj (in 1.87 sec).
  1 of 10 projects are up-to-date for restore.
  ##vso[build.updatebuildnumber]10.0.90-ci+azdo.14529387
  Graphics -> /home/vsts/work/1/s/artifacts/bin/Graphics/Debug/net10.0/Microsoft.Maui.Graphics.dll
  ##vso[build.updatebuildnumber]10.0.90-ci+azdo.14529387
  Essentials -> /home/vsts/work/1/s/artifacts/bin/Essentials/Debug/net10.0/Microsoft.Maui.Essentials.dll
  ##vso[build.updatebuildnumber]10.0.90-ci+azdo.14529387
  Core -> /home/vsts/work/1/s/artifacts/bin/Core/Debug/net10.0/Microsoft.Maui.dll
  ##vso[build.updatebuildnumber]10.0.90-ci+azdo.14529387
  Maps -> /home/vsts/work/1/s/artifacts/bin/Maps/Debug/net10.0/Microsoft.Maui.Maps.dll
  Controls.BindingSourceGen -> /home/vsts/work/1/s/artifacts/bin/Controls.BindingSourceGen/Debug/netstandard2.0/Microsoft.Maui.Controls.BindingSourceGen.dll
  ##vso[build.updatebuildnumber]10.0.90-ci+azdo.14529387
  Controls.Core -> /home/vsts/work/1/s/artifacts/bin/Controls.Core/Debug/net10.0/Microsoft.Maui.Controls.dll
  ##vso[build.updatebuildnumber]10.0.90-ci+azdo.14529387
  ##vso[build.updatebuildnumber]10.0.90-ci+azdo.14529387
  Controls.Maps -> /home/vsts/work/1/s/artifacts/bin/Controls.Maps/Debug/net10.0/Microsoft.Maui.Controls.Maps.dll
  Controls.Xaml -> /home/vsts/work/1/s/artifacts/bin/Controls.Xaml/Debug/net10.0/Microsoft.Maui.Controls.Xaml.dll
  TestUtils -> /home/vsts/work/1/s/artifacts/bin/TestUtils/Debug/netstandard2.0/Microsoft.Maui.TestUtils.dll
  Controls.Core.UnitTests -> /home/vsts/work/1/s/artifacts/bin/Controls.Core.UnitTests/Debug/net10.0/Microsoft.Maui.Controls.Core.UnitTests.dll
Test run for /home/vsts/work/1/s/artifacts/bin/Controls.Core.UnitTests/Debug/net10.0/Microsoft.Maui.Controls.Core.UnitTests.dll (.NETCoreApp,Version=v10.0)
VSTest version 18.0.1 (x64)

Starting test execution, please wait...
A total of 1 test files matched the specified pattern.
[xUnit.net 00:00:00.00] xUnit.net VSTest Adapter v2.8.2+699d445a1a (64-bit .NET 10.0.0)
[xUnit.net 00:00:00.14]   Discovering: Microsoft.Maui.Controls.Core.UnitTests
[xUnit.net 00:00:01.37]   Discovered:  Microsoft.Maui.Controls.Core.UnitTests
[xUnit.net 00:00:01.38]   Starting:    Microsoft.Maui.Controls.Core.UnitTests
[xUnit.net 00:00:01.51]     OldAdaptiveTriggerDetachedWhenVSGsReplacedAfterAttach [FAIL]
[xUnit.net 00:00:01.51]       Old AdaptiveTrigger should be detached after VSGs are replaced
[xUnit.net 00:00:01.51]       Stack Trace:
[xUnit.net 00:00:01.51]         /_/src/Controls/tests/Core.UnitTests/AdaptiveTriggerTests.cs(63,0): at Microsoft.Maui.Controls.Core.UnitTests.AdaptiveTriggerTests.OldAdaptiveTriggerDetachedWhenVSGsReplacedAfterAttach()
[xUnit.net 00:00:01.51]            at System.Reflection.MethodBaseInvoker.InterpretedInvoke_Method(Object obj, IntPtr* args)
[xUnit.net 00:00:01.51]            at System.Reflection.MethodBaseInvoker.InvokeWithNoArgs(Object obj, BindingFlags invokeAttr)
[xUnit.net 00:00:01.52]   Finished:    Microsoft.Maui.Controls.Core.UnitTests
  Passed ValidateAdaptiveTriggerDisconnects [60 ms]
  Passed ResizingWindowPageActivatesTrigger [11 ms]
  Failed OldAdaptiveTriggerDetachedWhenVSGsReplacedAfterAttach [1 ms]
  Error Message:
   Old AdaptiveTrigger should be detached after VSGs are replaced
  Stack Trace:
     at Microsoft.Maui.Controls.Core.UnitTests.AdaptiveTriggerTests.OldAdaptiveTriggerDetachedWhenVSGsReplacedAfterAttach() in /_/src/Controls/tests/Core.UnitTests/AdaptiveTriggerTests.cs:line 63
   at System.Reflection.MethodBaseInvoker.InterpretedInvoke_Method(Object obj, IntPtr* args)
   at System.Reflection.MethodBaseInvoker.InvokeWithNoArgs(Object obj, BindingFlags invokeAttr)

Test Run Failed.
Total tests: 3
     Passed: 2
     Failed: 1
 Total time: 2.0313 Seconds

🟢 With fix — 🧪 AdaptiveTriggerTests: PASS ✅ · 68s

  Determining projects to restore...
  All projects are up-to-date for restore.
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  Graphics -> /home/vsts/work/1/s/artifacts/bin/Graphics/Debug/net10.0/Microsoft.Maui.Graphics.dll
  ##vso[build.updatebuildnumber]10.0.90-ci+azdo.14529387
  Essentials -> /home/vsts/work/1/s/artifacts/bin/Essentials/Debug/net10.0/Microsoft.Maui.Essentials.dll
  ##vso[build.updatebuildnumber]10.0.90-ci+azdo.14529387
  Core -> /home/vsts/work/1/s/artifacts/bin/Core/Debug/net10.0/Microsoft.Maui.dll
  ##vso[build.updatebuildnumber]10.0.90-ci+azdo.14529387
  Maps -> /home/vsts/work/1/s/artifacts/bin/Maps/Debug/net10.0/Microsoft.Maui.Maps.dll
  Controls.BindingSourceGen -> /home/vsts/work/1/s/artifacts/bin/Controls.BindingSourceGen/Debug/netstandard2.0/Microsoft.Maui.Controls.BindingSourceGen.dll
  ##vso[build.updatebuildnumber]10.0.90-ci+azdo.14529387
  Controls.Core -> /home/vsts/work/1/s/artifacts/bin/Controls.Core/Debug/net10.0/Microsoft.Maui.Controls.dll
  ##vso[build.updatebuildnumber]10.0.90-ci+azdo.14529387
  Controls.Xaml -> /home/vsts/work/1/s/artifacts/bin/Controls.Xaml/Debug/net10.0/Microsoft.Maui.Controls.Xaml.dll
  ##vso[build.updatebuildnumber]10.0.90-ci+azdo.14529387
  Controls.Maps -> /home/vsts/work/1/s/artifacts/bin/Controls.Maps/Debug/net10.0/Microsoft.Maui.Controls.Maps.dll
  TestUtils -> /home/vsts/work/1/s/artifacts/bin/TestUtils/Debug/netstandard2.0/Microsoft.Maui.TestUtils.dll
  Controls.Core.UnitTests -> /home/vsts/work/1/s/artifacts/bin/Controls.Core.UnitTests/Debug/net10.0/Microsoft.Maui.Controls.Core.UnitTests.dll
Test run for /home/vsts/work/1/s/artifacts/bin/Controls.Core.UnitTests/Debug/net10.0/Microsoft.Maui.Controls.Core.UnitTests.dll (.NETCoreApp,Version=v10.0)
VSTest version 18.0.1 (x64)

Starting test execution, please wait...
A total of 1 test files matched the specified pattern.
[xUnit.net 00:00:00.00] xUnit.net VSTest Adapter v2.8.2+699d445a1a (64-bit .NET 10.0.0)
[xUnit.net 00:00:00.22]   Discovering: Microsoft.Maui.Controls.Core.UnitTests
[xUnit.net 00:00:02.39]   Discovered:  Microsoft.Maui.Controls.Core.UnitTests
[xUnit.net 00:00:02.41]   Starting:    Microsoft.Maui.Controls.Core.UnitTests
[xUnit.net 00:00:02.64]   Finished:    Microsoft.Maui.Controls.Core.UnitTests
  Passed ValidateAdaptiveTriggerDisconnects [106 ms]
  Passed ResizingWindowPageActivatesTrigger [20 ms]
  Passed OldAdaptiveTriggerDetachedWhenVSGsReplacedAfterAttach [1 ms]

Test Run Successful.
Total tests: 3
     Passed: 3
 Total time: 3.4235 Seconds

📁 Fix files reverted (2 files)

• src/Controls/src/Core/AdaptiveTrigger.cs
• src/Controls/src/Core/VisualStateManager.cs

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📱 UI Tests — VisualStateManager

Detected UI test categories: VisualStateManager

⚠️ Deep UI tests — 1 category (100 tests) could not run: OneTimeSetUp/fixture setup failure on the platform-pool agent — infrastructure, not a PR test failure (replaces in-process counts above).

🧪 UI Test Execution Results (deep, platform pool)

Category	Tests	Snapshot diffs
VisualStateManager	0/100 (setup failed; 100 marked failed)	—

⚠️ VisualStateManager — fixture setup failed for 100 tests

NUnit reported a OneTimeSetUp/fixture setup failure before test bodies ran; the TRX marked each affected test failed.

Multiple setup failure signatures were present; showing the first one. See the TRX artifact for all details.

OneTimeSetUp: System.TimeoutException : Timed out waiting for Go To Test button to appear (the app did not recover after crash-recovery attempts)
at Microsoft.Maui.TestCases.Tests.UtilExtensions.WaitForGoToTestButtonWithRecovery(IApp app, String timeoutMessage) in /_/src/Controls/tests/TestCases.Shared.Tests/UtilExtensions.cs:line 91
   at Microsoft.Maui.TestCases.Tests.UtilExtensions.NavigateToGallery(IApp app, String page) in /_/src/Controls/tests/TestCases.Shared.Tests/UtilExtensions.cs:line 37
   at Microsoft.Maui.TestCases.Tests._GalleryUITest.FixtureSetup() in /_/src/Controls/tests/TestCases.Shared.Tests/Tests/Issues/_GalleryUITest.cs:line 57
   at UITest.Appium.NUnit.UITestBase.OneTimeSetup() in /_/src/TestUtils/src/UITest.NUnit/UITestBase.cs:line 221
   at System.Reflection.MethodBaseInvoker.InterpretedInvoke_Method(Object obj, IntPtr* args)
   at System.Reflection.RuntimeMethodInfo.Invoke(Object obj, BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture)

📎 Download drop-deep-uitests artifact (TRX + snapshot diffs)

---

📋 Pre-Flight — Context & Validation

Issue: #36032 - AdaptiveTrigger leaks VisualElement when VisualStateGroups are replaced after attach
PR: #36240 - [WIP] Fix AdaptiveTrigger memory leak when VisualStateGroups are replaced after attach
Platforms Affected: Android, iOS, macOS/MacCatalyst (issue labels/repro); logic is shared Controls code
Files Changed: 2 implementation, 1 test

Key Findings

• #36032 reports a retention chain Window.SizeChanged -> old AdaptiveTrigger -> VisualElement -> BindingContext after visible controls replace VisualStateManager.VisualStateGroups at runtime.
• The PR fix detaches triggers from the old group list in VisualStateGroupsPropertyChanged, re-attaches incoming triggers when the element is already in a Window, and weakens AdaptiveTrigger's element reference as a safety net.
• Gate was already completed separately: AdaptiveTriggerTests fail without the fix and pass with the PR fix. Per instructions, gate verification was not re-run.
• PR discussion and inline review comments available through public API contained no prior error-level review findings.

Code Review Summary

Verdict: NEEDS_DISCUSSION
Confidence: low
Errors: 0 | Warnings: 0 | Suggestions: 0

Key code review findings:

• ℹ No code-review defects found in the PR diff.
• ℹ Blast radius is limited to runtime replacement of VisualStateGroups; no startup/static state impact.
• ℹ CI status could not be fully determined because gh is unauthenticated in this environment, so confidence is capped low.

Fix Candidates

#	Source	Approach	Test Result	Files Changed	Notes
PR	PR #36240	In VisualStateManager.VisualStateGroupsPropertyChanged, call SendDetached() on old triggers, update new groups, and call InvalidateStateTriggers(true) if already windowed; also change AdaptiveTrigger's element reference to WeakReference<VisualElement>.	✅ PASSED (Gate)	AdaptiveTrigger.cs, VisualStateManager.cs, AdaptiveTriggerTests.cs	Original PR fix; gate output is in gate/content.md.

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🔬 Code Review — Deep Analysis

Code Review — PR #36240

Independent Assessment

What this changes: Fixes AdaptiveTrigger lifecycle when VisualStateGroups are replaced on an already-windowed element: old triggers detach, new triggers attach, and AdaptiveTrigger no longer strongly retains the VisualElement.

Inferred motivation: Prevent stale Window.SizeChanged subscriptions from retaining old visual trees/view models after runtime VSM replacement.

Reconciliation with PR Narrative

Author claims: Fixes #36032 memory leak by detaching old triggers and attaching replacement triggers.
Agreement/disagreement: Matches the code and linked issue’s retention chain.

Prior Review Reconciliation

No prior ❌ Error findings found.

Blast Radius Assessment

• Runs for all instances: only when VisualStateGroups changes.
• Startup impact: no.
• Static/shared state: no.

CI Status

• Required-check result: undetermined via gh (gh auth login required). Public check-runs showed at least one maui-pr leg still in progress when reviewed.
• Classification: pending/undetermined.
• Action taken: confidence capped low. Gate already passed for AdaptiveTriggerTests and was not re-run.

Findings

No ❌ Error, ⚠️ Warning, or 💡 Suggestion findings.

Failure-Mode Probing

• Replacing VSM groups while windowed: old triggers receive SendDetached; new triggers attach.
• Window detach/reconnect: existing InvalidateStateTriggers path remains intact.
• Null/default window: attach skips subscription safely.

Verdict: NEEDS_DISCUSSION

Confidence: low
Summary: Code review found no correctness issues, and targeted gate tests passed. However, CI is pending/undetermined in this unauthenticated environment, so the skill rules prevent an LGTM verdict.

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🛠️ Fix — Analysis & Comparison

Fix Candidates

#	Source	Approach	Test Result	Files Changed	Notes
1	try-fix	Move trigger lifecycle ownership into VisualStateGroupList.VisualElement and mutation APIs.	✅ PASS	1 file (VisualStateManager.cs)	Broader abstraction-level fix; passes but is more invasive than necessary.
2	try-fix	Put attach/detach on VisualStateGroup.VisualElement; list setter only propagates element reassignment.	✅ PASS	1 file (VisualStateManager.cs)	Selected alternative: narrower than Candidate 1 and fewer files than PR while fixing the lifecycle boundary.
PR	PR #36240	Detach old triggers in VisualStateGroupsPropertyChanged, reattach new triggers with InvalidateStateTriggers(true), and make AdaptiveTrigger hold a weak element reference.	✅ PASSED (Gate)	2 implementation files + tests	Original PR fix; gate already proved fail-without/pass-with.

Iterative Expert Review and Test Loop

#	Expert guidance	Outcome	Lesson
1	MAUI expert suggested moving ownership to VisualStateGroupList for association/disassociation and list mutations.	✅ PASS	Correct but broader than the PR's replacement-path scope.
2	MAUI expert suggested moving lifecycle to VisualStateGroup.VisualElement instead of list mutation APIs.	✅ PASS	Better balance: fixes at group/element association boundary without changing AdaptiveTrigger.

Candidate Details

Candidate 1 — VisualStateGroupList owns trigger lifecycle

Analysis

Result: Pass

What happened: The targeted AdaptiveTriggerTests regression suite passed: 3 passed, 0 failed.

Why it worked: Replacing VisualStateGroups sets the old list's VisualElement to null, which now detaches all triggers in the old list before clearing group element references. Setting the new list's VisualElement attaches its triggers immediately when the target element already has a Window, covering the replacement-after-attach scenario without modifying AdaptiveTrigger.

Self-review: 0 findings; reviewed against MAUI lifecycle/logic/regression dimensions. Main risk is that the fix broadens lifecycle ownership into all VisualStateGroupList mutation APIs, making it more invasive than the PR's targeted replacement-path fix.

Insights: This abstraction-level approach passes the gate and handles additional group-list mutations, but it touches more surface area than the PR and is not clearly simpler.

See ../try-fix-1/content.md and ../try-fix-1/fix.diff for the full diff and captured test output.

Candidate 2 — VisualStateGroup attachment-boundary lifecycle

Analysis

Result: Pass

What happened: The targeted AdaptiveTriggerTests regression suite passed: 3 passed, 0 failed.

Why it worked: VisualStateGroupsPropertyChanged already clears the old list's VisualElement and assigns the new list's VisualElement. Propagating that assignment to each VisualStateGroup, and making each group detach/attach its own triggers at that boundary, removes the old trigger's Window.SizeChanged subscription and attaches replacement triggers for already-windowed elements.

Self-review: 0 findings; reviewed against MAUI lifecycle/logic/regression dimensions. The main watchpoint is trigger additions after group attachment, which this candidate intentionally does not broaden into because it matches the PR's replacement-path scope.

Insights: This candidate passes the gate while changing only VisualStateManager.cs and avoiding the PR's AdaptiveTrigger weak-reference safety-net change. It is a plausible better alternative because it fixes lifecycle at the existing group/element association boundary with fewer files than the PR.

See ../try-fix-2/content.md and ../try-fix-2/fix.diff for the full diff and captured test output.

Selection

Exhausted: No — stopped because Candidate 2 passed all targeted regression tests and is demonstrably preferable to both Candidate 1 and the PR fix for this review criterion.

Selected Fix: Candidate #2 — It changes only VisualStateManager.cs, avoids adding a weak-reference safety net to AdaptiveTrigger, and places trigger attach/detach at the VisualStateGroup.VisualElement lifecycle boundary that is already exercised by VisualStateGroupsPropertyChanged during replacement. Compared with the PR fix, it uses fewer implementation files and addresses the root lifecycle association rather than special-casing replacement in the attached-property callback.

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📝 Recommended PR Title & Description

Assessment: ✏️ Recommend updating — the current title still has a [WIP] prefix and the description omits the AdaptiveTrigger weak-reference safety-net change.

Recommended title

[Controls] VisualStateManager: Detach AdaptiveTriggers when replacing VisualStateGroups

Recommended description

### Issue Details
AdaptiveTrigger leaks memory when VisualStateGroups are replaced at runtime on a visible element. This causes entire view models (data) to stay in memory permanently even after navigation, growing by ~3 MB per page visit.

### Root Cause
VisualStateGroupsPropertyChanged in VisualStateManager.cs discards the old VisualStateGroups without calling SendDetached() on its triggers. The old AdaptiveTrigger stays subscribed to Window.SizeChanged, holding a strong reference to the VisualElement and its BindingContext forever.

### Description of Change
In VisualStateGroupsPropertyChanged, detach triggers from the old VisualStateGroups before unapplying old setters and clearing the old VisualElement association. This unsubscribes old AdaptiveTrigger instances from Window.SizeChanged when VisualStateGroups are replaced after the element is already attached.

After assigning the new VisualStateGroups, if the element is already in a Window, call visualElement.InvalidateStateTriggers(true) so the new triggers attach and activate immediately instead of waiting for a future Window change.

AdaptiveTrigger now stores its associated VisualElement through a WeakReference<VisualElement> while attached. This avoids a strong AdaptiveTrigger -> VisualElement retention path if a detach path is missed.

Validated the behavior in the following platforms
 
- [x] Android
- [x] Windows
- [x] iOS
- [x] Mac
 
### Issues Fixed
  
Fixes #36032 

### Output  ScreenShot

|Before|After|
|--|--|
| <img width="638" height="576" alt="image" src="https://github.com/user-attachments/assets/177dd499-9351-4edb-bd46-19b9c8d7c3ea" /> | <img width="642" height="613" alt="image" src="https://github.com/user-attachments/assets/136be499-da4b-4f4c-a357-ab7a21316a69" /> |

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🏁 Report — Final Recommendation

Comparative Report — PR #36240

Candidates Compared

Rank	Candidate	Regression result	Assessment
1	pr	✅ PASSED	Best overall. Directly fixes the submitted replacement-after-attach leak, attaches incoming triggers, keeps behavior localized to the affected attached-property callback, and adds the AdaptiveTrigger weak-reference safety net. Expert review found no actionable issues.
2	pr-plus-reviewer	✅ PASSED	Equivalent to pr; the expert reviewer produced no actionable feedback, so there is no modified sandbox diff to prefer over the raw PR.
3	try-fix-2	✅ PASS	Strong alternative that moves attach/detach to the VisualStateGroup.VisualElement lifecycle boundary and avoids changing AdaptiveTrigger. It is elegant, but it shifts lifecycle behavior into a broader internal setter and removes the PR's weak-reference safety net, so it is not clearly safer than the submitted fix.
4	try-fix-1	✅ PASS	Correct but more invasive. It changes VisualStateGroupList collection mutation behavior in addition to replacement, which increases blast radius beyond the issue's proven failing path.

Decision

Winning candidate: pr

All candidates with available test evidence passed the targeted regression suite, so no failed candidate outranks a passing one. Between the passing options, the PR fix is the best merge candidate because it is already present in the PR, is narrowly targeted to VisualStateGroupsPropertyChanged, retains existing window lifecycle behavior, and includes a weak-reference safety net in AdaptiveTrigger for any missed detach path. try-fix-2 is a plausible architectural alternative, but the expert review did not find a defect that justifies replacing the submitted PR with a different lifecycle model.

Notes

• pr-plus-reviewer did not produce a distinct candidate because inline-findings.json is [].
• Required GitHub CI and review surfaces were unavailable due missing gh authentication in this environment. The gate result supplied for this review was used as the regression evidence and was not rerun.

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🧭 Next Steps — review latest findings

No alternative fix was selected for this run. Review the session findings and CI results before merging.

[Copilot]

Pull request overview

Fixes a memory-leak scenario where AdaptiveTrigger instances can remain subscribed to Window.SizeChanged (and retain view models) when VisualStateManager.VisualStateGroups is replaced on an already-attached VisualElement.

Changes:

• Detach state triggers from the old visual state groups during VisualStateGroupsPropertyChanged to ensure event unsubscription occurs before the old VSM associations are cleared.
• When visual state groups are replaced while the element is already in a Window, immediately attach triggers for the new groups via InvalidateStateTriggers(true).
• Add a regression unit test verifying that the old trigger detaches and the new trigger attaches when VSGs are replaced after attach.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
src/Controls/tests/Core.UnitTests/AdaptiveTriggerTests.cs	Adds regression test covering detach/attach behavior when replacing VSGs after window attach.
src/Controls/src/Core/VisualStateManager.cs	Ensures old triggers are detached on VSG replacement and new triggers are attached immediately when already in a window.
src/Controls/src/Core/AdaptiveTrigger.cs	Switches the stored visual element reference to a weak reference to avoid a strong retention path if detach is missed.