[leak-fix] Fix ListView.RefreshCommand memory leak (Fixes #36344) by github-actions[bot] · Pull Request #36369 · dotnet/maui

github-actions · 2026-07-04T03:52:19Z

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!

🤖 AI-generated. This pull request was produced automatically by the Memory Leak Fixer agentic workflow (leak-fixer) for dotnet/maui. It contains a regression test empirically proven to fail without the fix and pass with it (red → green on this run's main source).

Fixes #36344
Refs: #36344
Target branch: main
Attempt: 1/3

The leak

ListView.OnRefreshCommandChanged subscribed to RefreshCommand.CanExecuteChanged with a plain instance handler:

newCommand.CanExecuteChanged += OnCommandCanExecuteChanged;

Because OnCommandCanExecuteChanged is an instance method, the delegate's target is the ListView. When the assigned ICommand is long-lived (a singleton/DI/static command, or a reused view-model command) and exposes CanExecuteChanged as a strong .NET event, that event's invocation list roots the entire ListView — including its cells, templates and binding context. The matching unsubscribe (-=) only runs when RefreshCommand is reassigned, never when the ListView is simply unloaded, so the control is never released.

Microsoft.Maui.Controls.Command routes CanExecuteChanged through a WeakEventManager, so it does not reproduce the leak. The leak surfaces with any custom ICommand (e.g. CommunityToolkit's RelayCommand) that raises the event directly — which is exactly what the issue reports.

The fix

Replace the direct subscription with a WeakCommandSubscription — the same weak-subscription helper already used by CommandElement, Button and RefreshView:

_refreshCommandSubscription = new WeakCommandSubscription(this, newCommand, OnCommandCanExecuteChanged);

On reassignment the previous subscription is disposed. WeakCommandSubscription holds only a weak reference to the ListView (via DependentHandle), so the command can no longer keep it alive, while CanExecuteChanged is still delivered for as long as the ListView is reachable. No public API changes.

Regression test

RefreshCommandDoesNotLeakListView (in Controls.Core.UnitTests/ListViewTests.cs) assigns a custom strong-event ICommand to ListView.RefreshCommand, drops the only strong reference to the ListView, forces GC and asserts the ListView was collected while the command stays alive.

Empirical red → green on this run's source:

Without the fix (red): Failed RefreshCommandDoesNotLeakListView [895 ms] — ListView should not be alive! (Failed: 1)
With the fix (green): Passed RefreshCommandDoesNotLeakListView [47 ms] (Passed: 1, Test Run Successful)
No regressions: full ListViewTests class — Total tests: 71, Passed: 71 (including RefreshCommandCanExecute and SendRefreshingDoesNothingWhenCannotExecute, which exercise the CanExecute path)

Scope

Managed, cross-platform change only — one product file (src/Controls/src/Core/ListView/ListView.cs) plus the test. No existing test was muted, skipped or weakened; no behavioural change to RefreshCommand/CanExecute handling.

Generated by Memory Leak Fixer · 2.4K AIC · ⌖ 101 AIC · ⊞ 60.6K · ◷

ListView subscribed to RefreshCommand.CanExecuteChanged with a plain instance handler, so a long-lived ICommand whose CanExecuteChanged is a strong .NET event rooted the entire ListView and it was never released on unload. Replace the direct subscription with a WeakCommandSubscription (the same hardening already used by CommandElement, Button and RefreshView) so the command no longer keeps the ListView alive. Adds a Controls.Core.UnitTests regression test that fails without this fix. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

MauiBot

AI Review Summary

@github-actions[bot] — new AI review results are available based on this last commit: fb484f8. To request a fresh review after new comments or commits, comment /review rerun.

🔍 Custom Prompt Analysis — maintainer-requested

● AI-generated — supplementary analysis from a maintainer-supplied custom prompt (GitHub Copilot CLI).

Requested: Does this ListView.RefreshCommand leak fix fully cover command re-assignment/re-use, and are the memory tests adequate? Be concise.

ListView.RefreshCommand Leak Fix

Conclusion: The implementation looks sound for normal command reassignment and shared-command reuse, but the new memory test only proves the single-command leak scenario.

Command Reassignment / Reuse

Reassignment is handled by disposing the previous _refreshCommandSubscription before subscribing to the new command.
Clearing RefreshCommand also disposes the subscription and restores RefreshAllowed = true.
Reusing the same long-lived command across multiple ListView instances should be safe: each WeakCommandSubscription weakly ties the callback to its own ListView, so a command event should not strongly root disposed/collected views.
Minor robustness note: disposal is guarded by oldCommand != null; this matches normal bindable-property transitions, though the nearby SearchHandler pattern disposes unconditionally.

Test Adequacy

The new test is valuable: it uses a strong CanExecuteChanged event command, keeps the command alive, and verifies the ListView can be collected.
It does not directly cover reassignment from command A to command B.
It does not cover shared command reuse across multiple ListView instances where one view is collected and another remains active.
Existing clear-subscription coverage uses Microsoft.Maui.Controls.Command, whose weak event path would not reproduce the strong-event leak.

Recommended Follow-up

Add one focused test with a strong-event command for reassignment/clear, and optionally one shared-command test to prove one collected ListView does not affect another still using the same command.

🗂️ Review Sessions — click to expand

🚦 Gate — Test Before & After Fix

Gate Result: ✅ PASSED

Platform: ANDROID · Base: main · Merge base: dab8abc4

Test	Without Fix (expect FAIL)	With Fix (expect PASS)
🧪 ListViewTests `ListViewTests`	✅ FAIL — 106s	✅ PASS — 81s

🔴 Without fix — 🧪 ListViewTests: FAIL ✅ · 106s

  Determining projects to restore...
  Restored /home/vsts/work/1/s/src/Controls/tests/Core.UnitTests/Controls.Core.UnitTests.csproj (in 5.59 sec).
  Restored /home/vsts/work/1/s/src/Controls/src/Xaml/Controls.Xaml.csproj (in 2.54 sec).
  Restored /home/vsts/work/1/s/src/Controls/Maps/src/Controls.Maps.csproj (in 8.97 sec).
  Restored /home/vsts/work/1/s/src/TestUtils/src/TestUtils/TestUtils.csproj (in 5 ms).
  Restored /home/vsts/work/1/s/src/Controls/src/Core/Controls.Core.csproj (in 44 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 31 ms).
  Restored /home/vsts/work/1/s/src/Core/src/Core.csproj (in 64 ms).
  Restored /home/vsts/work/1/s/src/Core/maps/src/Maps.csproj (in 29 ms).
  1 of 10 projects are up-to-date for restore.
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  ##vso[build.updatebuildnumber]10.0.90-ci+azdo.14587797
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  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 00:00:00.15]   Discovering: Microsoft.Maui.Controls.Core.UnitTests
[xUnit.net 00:00:01.21]   Discovered:  Microsoft.Maui.Controls.Core.UnitTests
[xUnit.net 00:00:01.23]   Starting:    Microsoft.Maui.Controls.Core.UnitTests
  Passed HeaderTemplatedSetToNull [35 ms]
  Passed FooterViewButTemplated [7 ms]
  Passed StopsListeningToCommandAfterCleared [2 ms]
  Passed Tapping a different item (row) that is equal to the current item selection should still raise ItemSelected [12 ms]
  Passed ScrollToDelayed [5 ms]
  Passed HeaderTemplated [2 ms]
  Passed SendRefreshingCanBind [2 ms]
  Passed BeginRefreshDoesNothingWhenCannotExecute [< 1 ms]
  Passed GetSizeRequest [6 ms]
  Passed HeaderNoTemplate [< 1 ms]
  Passed DefaultCacheStrategy [2 ms]
  Passed RefreshCommandCanExecuteChanges(initial: False) [3 ms]
  Passed RefreshCommandCanExecuteChanges(initial: True) [< 1 ms]
  Passed ItemTemplateIsNullObjectExecutesToString [3 ms]
  Passed FooterTemplateChanged [1 ms]
  Passed HeaderTemplatedChangedToView [< 1 ms]
  Passed HeaderTemplateChanged [< 1 ms]
  Passed ForceUpdateSizeCalledOnViewCellDoesntCrash [28 ms]
  Passed FooterTemplatedSetToNull [< 1 ms]
  Passed DoesNotThrowWhenMovingInSource [3 ms]
  Passed FooterViewChanged [< 1 ms]
  Passed RefreshCommand [< 1 ms]
  Passed GroupedCollectionChangedMultipleFires [20 ms]
  Passed HeaderViewChanged [< 1 ms]
  Passed EnforcesCachingStrategy(platform: "Android", expected: RecycleElement) [< 1 ms]
  Passed EnforcesCachingStrategy(platform: "UWP", expected: RetainElement) [< 1 ms]
  Passed EnforcesCachingStrategy(platform: "Other", expected: RetainElement) [< 1 ms]
[xUnit.net 00:00:02.73]     RefreshCommandDoesNotLeakListView [FAIL]
[xUnit.net 00:00:02.73]       ListView should not be alive!
[xUnit.net 00:00:02.74]       Stack Trace:
[xUnit.net 00:00:02.74]         /_/src/Controls/tests/Core.UnitTests/ListViewTests.cs(59,0): at Microsoft.Maui.Controls.Core.UnitTests.ListViewTests.RefreshCommandDoesNotLeakListView()
[xUnit.net 00:00:02.74]         --- End of stack trace from previous location ---
  Passed EnforcesCachingStrategy(platform: "iOS", expected: RecycleElement) [< 1 ms]
  Passed TemplateNullObject [< 1 ms]
  Passed We should be able to set selected item when using ReadOnlyList [1 ms]
  Passed ChildElementsParentIsNulledWhenRemoved [< 1 ms]
  Passed DoesNotRetainInRecycleMode [< 1 ms]
  Passed DoesNotCrashWhenAddingToSource [< 1 ms]
  Failed RefreshCommandDoesNotLeakListView [1 s]
  Error Message:
   ListView should not be alive!
  Stack Trace:
     at Microsoft.Maui.Controls.Core.UnitTests.ListViewTests.RefreshCommandDoesNotLeakListView() in /_/src/Controls/tests/Core.UnitTests/ListViewTests.cs:line 59
--- End of stack trace from previous location ---
  Passed HeaderViewButTemplated [< 1 ms]
  Passed EndRefresh [< 1 ms]
  Passed CanRefreshAfterCantExecuteCommand [< 1 ms]
  Passed FooterTemplated [< 1 ms]
  Passed ScrollToInvalid [1 ms]
  Passed ScrollTo [< 1 ms]
  Passed HeaderAsView [< 1 ms]
  Passed FooterTemplateChangedNoObject [< 1 ms]
  Passed FooterObjectTemplatedChanged [1 ms]
  Passed A cell being tapped from the UI should raise both tapped events, but not change ItemSelected [1 ms]
  Passed You should be able to set ItemsSource without having set the other properties first without issue [< 1 ms]
  Passed FooterTemplatedChangedToView [< 1 ms]
  Passed CollectionChangedMultipleFires [< 1 ms]
  Passed HeaderTemplateChangedNoObject [< 1 ms]
  Passed Setting GroupDisplayBinding or GroupHeaderTemplate when the other is set should set the other one to null. [< 1 ms]
  Passed UncollectableHeaderReferences [137 ms]
  Passed Setting Header and Footer should pass BindingContext. [1 ms]
  Passed TestTemplating [< 1 ms]
  Passed FooterAsView [< 1 ms]
  Passed ChildElementsParentIsNulledWhenReset [< 1 ms]
  Passed RefreshCommandCanExecute(initial: False) [< 1 ms]
  Passed RefreshCommandCanExecute(initial: True) [< 1 ms]
  Passed DefaultGroupHeaderTemplates [< 1 ms]
  Passed TestConstructor [3 ms]
  Passed FooterChangedNoTemplate [< 1 ms]
  Passed BeginRefresh [< 1 ms]
  Passed GetSizeRequestUneven [< 1 ms]
  Passed HeaderObjectTemplatedChanged [< 1 ms]
  Passed ScrollToGroup [< 1 ms]
[xUnit.net 00:00:02.90]   Finished:    Microsoft.Maui.Controls.Core.UnitTests
  Passed HeaderChangedNoTemplate [< 1 ms]
  Passed Setting BindingContext should trickle down to Header and Footer. [< 1 ms]
  Passed FooterNoTemplate [< 1 ms]
  Passed SendRefreshingDoesNothingWhenCannotExecute [< 1 ms]
  Passed SettingSelectItemManuallyBetweenTwoTapsFiresPropertyChanged [< 1 ms]
  Passed SendRefreshing [< 1 ms]
  Passed SettingIsRefreshingDoesntFireEvent [< 1 ms]
  Passed Setting GroupDisplayBinding or GroupHeaderTemplate when the other is set should set the other one to null. [< 1 ms]
  Passed ChildElementsParentIsNulledWhenCleared [< 1 ms]

Test Run Failed.
Total tests: 72
     Passed: 71
     Failed: 1
 Total time: 3.3974 Seconds

🟢 With fix — 🧪 ListViewTests: PASS ✅ · 81s

  Determining projects to restore...
  All projects are up-to-date for restore.
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  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 00:00:00.15]   Discovering: Microsoft.Maui.Controls.Core.UnitTests
[xUnit.net 00:00:01.22]   Discovered:  Microsoft.Maui.Controls.Core.UnitTests
[xUnit.net 00:00:01.25]   Starting:    Microsoft.Maui.Controls.Core.UnitTests
  Passed HeaderTemplatedSetToNull [34 ms]
  Passed FooterViewButTemplated [6 ms]
  Passed StopsListeningToCommandAfterCleared [2 ms]
  Passed Tapping a different item (row) that is equal to the current item selection should still raise ItemSelected [11 ms]
  Passed ScrollToDelayed [4 ms]
  Passed HeaderTemplated [2 ms]
  Passed SendRefreshingCanBind [2 ms]
  Passed BeginRefreshDoesNothingWhenCannotExecute [< 1 ms]
  Passed GetSizeRequest [6 ms]
  Passed HeaderNoTemplate [< 1 ms]
  Passed DefaultCacheStrategy [2 ms]
  Passed RefreshCommandCanExecuteChanges(initial: False) [3 ms]
  Passed RefreshCommandCanExecuteChanges(initial: True) [< 1 ms]
  Passed ItemTemplateIsNullObjectExecutesToString [3 ms]
  Passed FooterTemplateChanged [1 ms]
  Passed HeaderTemplatedChangedToView [1 ms]
  Passed HeaderTemplateChanged [< 1 ms]
  Passed ForceUpdateSizeCalledOnViewCellDoesntCrash [25 ms]
  Passed FooterTemplatedSetToNull [< 1 ms]
  Passed DoesNotThrowWhenMovingInSource [3 ms]
  Passed FooterViewChanged [< 1 ms]
  Passed RefreshCommand [< 1 ms]
  Passed GroupedCollectionChangedMultipleFires [18 ms]
  Passed HeaderViewChanged [< 1 ms]
  Passed EnforcesCachingStrategy(platform: "Android", expected: RecycleElement) [< 1 ms]
  Passed EnforcesCachingStrategy(platform: "UWP", expected: RetainElement) [< 1 ms]
  Passed EnforcesCachingStrategy(platform: "Other", expected: RetainElement) [< 1 ms]
  Passed EnforcesCachingStrategy(platform: "iOS", expected: RecycleElement) [< 1 ms]
  Passed TemplateNullObject [< 1 ms]
  Passed We should be able to set selected item when using ReadOnlyList [2 ms]
  Passed ChildElementsParentIsNulledWhenRemoved [< 1 ms]
  Passed DoesNotRetainInRecycleMode [< 1 ms]
  Passed DoesNotCrashWhenAddingToSource [< 1 ms]
  Passed RefreshCommandDoesNotLeakListView [34 ms]
  Passed HeaderViewButTemplated [< 1 ms]
  Passed EndRefresh [< 1 ms]
  Passed CanRefreshAfterCantExecuteCommand [< 1 ms]
  Passed FooterTemplated [< 1 ms]
  Passed ScrollToInvalid [1 ms]
  Passed ScrollTo [< 1 ms]
  Passed HeaderAsView [< 1 ms]
  Passed FooterTemplateChangedNoObject [< 1 ms]
  Passed FooterObjectTemplatedChanged [< 1 ms]
  Passed A cell being tapped from the UI should raise both tapped events, but not change ItemSelected [1 ms]
  Passed You should be able to set ItemsSource without having set the other properties first without issue [< 1 ms]
  Passed FooterTemplatedChangedToView [< 1 ms]
  Passed CollectionChangedMultipleFires [< 1 ms]
  Passed HeaderTemplateChangedNoObject [< 1 ms]
  Passed Setting GroupDisplayBinding or GroupHeaderTemplate when the other is set should set the other one to null. [< 1 ms]
  Passed UncollectableHeaderReferences [108 ms]
  Passed Setting Header and Footer should pass BindingContext. [1 ms]
  Passed TestTemplating [1 ms]
  Passed FooterAsView [< 1 ms]
  Passed ChildElementsParentIsNulledWhenReset [< 1 ms]
  Passed RefreshCommandCanExecute(initial: False) [< 1 ms]
  Passed RefreshCommandCanExecute(initial: True) [< 1 ms]
  Passed DefaultGroupHeaderTemplates [< 1 ms]
  Passed TestConstructor [3 ms]
  Passed FooterChangedNoTemplate [< 1 ms]
  Passed BeginRefresh [< 1 ms]
  Passed GetSizeRequestUneven [< 1 ms]
  Passed HeaderObjectTemplatedChanged [< 1 ms]
  Passed ScrollToGroup [< 1 ms]
[xUnit.net 00:00:01.63]   Finished:    Microsoft.Maui.Controls.Core.UnitTests
  Passed HeaderChangedNoTemplate [< 1 ms]
  Passed Setting BindingContext should trickle down to Header and Footer. [< 1 ms]
  Passed FooterNoTemplate [< 1 ms]
  Passed SendRefreshingDoesNothingWhenCannotExecute [< 1 ms]
  Passed SettingSelectItemManuallyBetweenTwoTapsFiresPropertyChanged [< 1 ms]
  Passed SendRefreshing [< 1 ms]
  Passed SettingIsRefreshingDoesntFireEvent [< 1 ms]
  Passed Setting GroupDisplayBinding or GroupHeaderTemplate when the other is set should set the other one to null. [< 1 ms]
  Passed ChildElementsParentIsNulledWhenCleared [< 1 ms]

Test Run Successful.
Total tests: 72
     Passed: 72
 Total time: 2.1568 Seconds

📁 Fix files reverted (1 files)

src/Controls/src/Core/ListView/ListView.cs

📱 UI Tests — ListView

Detected UI test categories: ListView

[!WARNING]
No UI test results were produced for the detected categories. The platform-pool run
returned no results — most often because the PR build failed (see the Gate section) or
the deep UI test stage was skipped. Fix the build/gate issues and comment /review rerun
to get UI test results.

📋 Pre-Flight — Context & Validation

Issue: #36344 - [leak-scan] ListView.RefreshCommand leaks the control via strong ICommand.CanExecuteChanged (no weak proxy, no unload teardown)
PR: #36369 - [leak-fix] Fix ListView.RefreshCommand memory leak (Fixes #36344)
Platforms Affected: android requested for testing; product change is managed Controls code and affects all platforms using ListView.RefreshCommand.
Files Changed: 1 implementation, 1 test

Key Findings

Issue #36344 reports that ListView.RefreshCommand subscribed directly to ICommand.CanExecuteChanged, so a long-lived command with a strong .NET event could retain the ListView, cells, templates, and binding context after navigation unless RefreshCommand was reassigned.
PR #36369 replaces the direct strong event subscription with MAUI's existing WeakCommandSubscription helper and disposes the subscription when RefreshCommand changes or is cleared.
The PR adds RefreshCommandDoesNotLeakListView, a Controls Core unit regression using a custom strong-event ICommand; the caller-provided gate result already proved the test fails without the fix and passes with the PR fix.
Public PR/issue discussion available without gh auth contained only a /review request and no technical objections. Inline comments were empty. Prior MauiBot review summary reported no actionable findings.
The impacted UI test category is ListView; existing local gate artifacts and uitests/content.md were left untouched.

Code Review Summary

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

Key code review findings:

No actionable implementation findings. The PR's localized weak-command subscription matches existing MAUI command patterns used by sibling controls.
Required-check verification through gh pr checks --required was unavailable because gh is unauthenticated in this environment, so code-review confidence is capped low and the verdict cannot be LGTM.
Failure-mode probes: long-lived commands no longer root ListView; command replacement/clear disposes the prior subscription; CanExecuteChanged behavior remains covered by existing unit tests; no startup/static state impact.

Fix Candidates

#	Source	Approach	Test Result	Files Changed	Notes
PR	PR #36369	Store a per-`ListView` `WeakCommandSubscription` for `RefreshCommand`; dispose it on command replacement/clear.	PASSED (Gate)	`src/Controls/src/Core/ListView/ListView.cs`, `src/Controls/tests/Core.UnitTests/ListViewTests.cs`	Original PR; gate already completed and was not re-run.

🔬 Code Review — Deep Analysis

Code Review - PR #36369

Independent Assessment

What this changes: ListView.RefreshCommand now uses WeakCommandSubscription instead of directly subscribing OnCommandCanExecuteChanged to ICommand.CanExecuteChanged. A regression test verifies a long-lived strong-event command does not keep ListView alive.

Inferred motivation: Prevent RefreshCommand.CanExecuteChanged from strongly rooting disposed/unreferenced ListView instances while preserving RefreshAllowed updates.

Reconciliation with PR Narrative

Author claims: Fixes a ListView.RefreshCommand memory leak with strong-event ICommand implementations; uses existing MAUI weak command infrastructure; adds red/green leak coverage.

Agreement/disagreement: Agrees. The implementation at src/Controls/src/Core/ListView/ListView.cs:100 and :768-775 matches the stated fix. The test at src/Controls/tests/Core.UnitTests/ListViewTests.cs:39-61 targets the described leak.

Prior Review Reconciliation

No prior error findings found. Prior MauiBot review reported zero errors/warnings/suggestions; inline review comments were empty; issue comments contained only /review.

Blast Radius Assessment

Runs for all instances: Only ListView instances with RefreshCommand set.
Startup impact: No.
Static/shared state: No.
Scope: Managed Controls-level command subscription; no platform handler changes.

CI Status

Required-check result: unavailable - gh pr checks 36369 --repo dotnet/maui --required returned exit 4 because gh is unauthenticated.
Classification: undetermined.
Action taken: capped confidence low; no LGTM per skill rule for undetermined CI.

Findings

No actionable Error, Warning, or Suggestion findings.

Failure-Mode Probing

Command outlives ListView: WeakCommandSubscription uses DependentHandle, so the command event roots the proxy, not the ListView.
Command changes/clears: old subscription is disposed when oldCommand != null, matching the property-change lifecycle.
CanExecuteChanged after collection: proxy disposes itself when the primary bindable object is gone.
Existing refresh behavior: RefreshAllowed = newCommand.CanExecute(null) and OnCommandCanExecuteChanged behavior are preserved.

Verdict: NEEDS_DISCUSSION

Confidence: low
Summary: Code review found no implementation issues, and the approach is consistent with existing MAUI weak-command patterns. However, required CI status could not be verified in this environment, so the skill rules prohibit LGTM.

🛠️ Fix — Analysis & Comparison

Fix Candidates

#	Source	Approach	Test Result	Files Changed	Notes
1	try-fix	Static per-command weak subscriber registry keyed by `ICommand`; forwards to weak `ListView` references.	PASS - 72/72	1 file	Passes, but worse than PR due to global state, locking, and multi-subscriber cleanup complexity.
2	try-fix	Self-removing weak event delegate closure per command assignment.	PASS - 72/72	1 file	Passes, but worse than PR because stale delegates remain on old commands until they raise again.
3	try-fix	Strong subscription scoped to handler lifecycle; subscribe only while handler-connected.	FAIL - 70/72	1 file	Fails `RefreshCommandCanExecuteChanges` because headless/no-handler `CanExecuteChanged` no longer updates `RefreshAllowed`.
PR	PR #36369	Per-`ListView` `WeakCommandSubscription` field using existing MAUI helper; dispose on command replacement/clear.	PASSED (Gate)	2 files	Original PR; simplest passing candidate and uses existing pattern.

Cross-Pollination

Model/Reviewer	Round	New Ideas?	Details
maui-expert-reviewer	1	Yes	Proposed candidate 1: static per-command weak subscriber registry.
maui-expert-reviewer	2	Yes	After candidate 1 passed but was not better, proposed candidate 2: self-removing weak delegate closure.
maui-expert-reviewer	3	Yes	After candidate 2 passed but was not better, proposed candidate 3: handler-lifecycle-scoped strong subscription.
maui-expert-reviewer	Exhaustion	No	"NO NEW IDEAS": remaining realistic variants collapse into per-instance weak subscription with explicit disposal, or lose correctness/delay cleanup/add global mutable state/depend on handler lifecycle.

Exhausted: Yes
Selected Fix: PR #36369 - The PR's WeakCommandSubscription approach is the best candidate. It passes the gate, preserves headless CanExecuteChanged behavior, disposes promptly on command replacement/clear, avoids global shared state, and reuses an existing MAUI helper rather than introducing custom weak-event machinery.

Test Command Used for Candidates

dotnet test src/Controls/tests/Core.UnitTests/Controls.Core.UnitTests.csproj --no-restore --filter "FullyQualifiedName~ListViewTests" --logger "console;verbosity=normal"

Candidate Artifacts

try-fix-1/content.md, try-fix-1/fix.diff, try-fix-1/test-output.log
try-fix-2/content.md, try-fix-2/fix.diff, try-fix-2/test-output.log
try-fix-3/content.md, try-fix-3/fix.diff, try-fix-3/test-output.log

🏁 Report — Final Recommendation

Comparative Fix Report — PR #36369

Candidates

Rank	Candidate	Test Result	Assessment
1	`pr`	PASSED (Gate)	Best candidate. Uses MAUI's existing `WeakCommandSubscription`, keeps ownership local to the `ListView`, disposes promptly on command replacement/clear, and preserves headless/control-level `CanExecuteChanged` behavior.
2	`pr-plus-reviewer`	PASSED (same as `pr`)	Expert reviewer found no actionable changes, so this is identical to `pr`. It ties with `pr` technically but does not improve on the submitted fix.
3	`try-fix-2`	PASS - 72/72	Uses a self-removing weak delegate closure. It passes tests, but replaced/cleared commands retain stale delegates until they raise `CanExecuteChanged` again, so cleanup is delayed and repeated replacements can accumulate closure objects.
4	`try-fix-1`	PASS - 72/72	Uses a static per-command weak subscriber registry. It passes tests, but adds global mutable state, locking, weak-reference cleanup, and multi-subscriber bookkeeping for a problem the existing per-instance helper already solves.
5	`try-fix-3`	FAIL - 70/72	Handler-lifecycle-scoped strong subscription fixes the leak case but regresses existing `RefreshCommandCanExecuteChanges` behavior for no-handler/headless controls. Failed regression candidates must rank below passing candidates.

Winning candidate

Winner: pr

The raw PR fix is the best solution. It is the smallest passing implementation, reuses the existing WeakCommandSubscription pattern used elsewhere in Controls, avoids new global/shared state, unsubscribes promptly when the command changes, and preserves current RefreshAllowed update semantics. The expert reviewer had no actionable feedback, so pr-plus-reviewer is functionally identical and does not supersede the original PR.

Notes

Gate result supplied by the orchestrator: tests fail without the fix and pass with the PR fix.
Required PR checks could not be independently queried because gh is unauthenticated in this environment; this limits review confidence but does not change the candidate ranking because the comparative gate/candidate test results are already available.

🧭 Next Steps — review latest findings

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

…6369) > [!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](https://github.com/dotnet/maui/wiki/Testing-PR-Builds) from this PR and let us know in a comment if this change resolves your issue. Thank you! > 🤖 **AI-generated.** This pull request was produced automatically by the **Memory Leak Fixer** agentic workflow (`leak-fixer`) for dotnet/maui. It contains a regression test empirically proven to fail without the fix and pass with it (red → green on this run's `main` source). Fixes #36344 Refs: #36344 Target branch: main Attempt: 1/3 ## The leak `ListView.OnRefreshCommandChanged` subscribed to `RefreshCommand.CanExecuteChanged` with a plain instance handler: ```csharp newCommand.CanExecuteChanged += OnCommandCanExecuteChanged; ``` Because `OnCommandCanExecuteChanged` is an instance method, the delegate's target is the `ListView`. When the assigned `ICommand` is long-lived (a singleton/DI/static command, or a reused view-model command) **and** exposes `CanExecuteChanged` as a strong .NET event, that event's invocation list roots the entire `ListView` — including its cells, templates and binding context. The matching unsubscribe (`-=`) only runs when `RefreshCommand` is reassigned, never when the `ListView` is simply unloaded, so the control is never released. > `Microsoft.Maui.Controls.Command` routes `CanExecuteChanged` through a `WeakEventManager`, so it does **not** reproduce the leak. The leak surfaces with any custom `ICommand` (e.g. CommunityToolkit's `RelayCommand`) that raises the event directly — which is exactly what the issue reports. ## The fix Replace the direct subscription with a `WeakCommandSubscription` — the same weak-subscription helper already used by `CommandElement`, `Button` and `RefreshView`: ```csharp _refreshCommandSubscription = new WeakCommandSubscription(this, newCommand, OnCommandCanExecuteChanged); ``` On reassignment the previous subscription is disposed. `WeakCommandSubscription` holds only a weak reference to the `ListView` (via `DependentHandle`), so the command can no longer keep it alive, while `CanExecuteChanged` is still delivered for as long as the `ListView` is reachable. No public API changes. ## Regression test `RefreshCommandDoesNotLeakListView` (in `Controls.Core.UnitTests/ListViewTests.cs`) assigns a custom strong-event `ICommand` to `ListView.RefreshCommand`, drops the only strong reference to the `ListView`, forces GC and asserts the `ListView` was collected while the command stays alive. Empirical red → green on this run's source: - **Without the fix (red):** `Failed RefreshCommandDoesNotLeakListView [895 ms]` — `ListView should not be alive!` (Failed: 1) - **With the fix (green):** `Passed RefreshCommandDoesNotLeakListView [47 ms]` (Passed: 1, Test Run Successful) - **No regressions:** full `ListViewTests` class — Total tests: 71, Passed: 71 (including `RefreshCommandCanExecute` and `SendRefreshingDoesNothingWhenCannotExecute`, which exercise the `CanExecute` path) ## Scope Managed, cross-platform change only — one product file (`src/Controls/src/Core/ListView/ListView.cs`) plus the test. No existing test was muted, skipped or weakened; no behavioural change to `RefreshCommand`/`CanExecute` handling. > Generated by [Memory Leak Fixer](https://github.com/dotnet/maui/actions/runs/28693580490) · 2.4K AIC · ⌖ 101 AIC · ⊞ 60.6K · [◷](https://github.com/search?q=repo%3Adotnet%2Fmaui+%22gh-aw-workflow-id%3A+leak-fixer%22&type=pullrequests)    Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com> Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com> Co-authored-by: Jakub Florkowski <42434498+kubaflo@users.noreply.github.com>

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MauiBot added s/agent-gate-passed AI verified tests catch the bug (fail without fix, pass with fix) s/agent-fix-pr-picked AI could not beat the PR fix - PR is the best among all candidates s/agent-reviewed PR was reviewed by AI agent workflow (full 4-phase review) labels Jul 4, 2026

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github-actions Bot mentioned this pull request Jul 5, 2026

[repo-status] Daily Status Report — July 5, 2026 #36394

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[repo-status] Daily Repo Status — July 8, 2026 #36438

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kubaflo changed the base branch from main to inflight/current July 8, 2026 11:00

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kubaflo marked this pull request as ready for review July 8, 2026 11:01

kubaflo merged commit 9c8ce18 into inflight/current Jul 8, 2026
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[repo-status] Daily Repo Status — July 9, 2026 #36463

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kubaflo mentioned this pull request Jul 12, 2026

[leak-scan] ListView.RefreshCommand leaks the control via strong ICommand.CanExecuteChanged (no weak proxy, no unload teardown) #36344

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kubaflo mentioned this pull request Jul 19, 2026

Harden memory leak workflow de-duplication and cadence #36664

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[leak-fix] Fix ListView.RefreshCommand memory leak (Fixes #36344) - #36369

[leak-fix] Fix ListView.RefreshCommand memory leak (Fixes #36344)#36369
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AI Review Summary

ListView.RefreshCommand Leak Fix

Command Reassignment / Reuse

Test Adequacy

Recommended Follow-up

Gate Result: ✅ PASSED

Key Findings

Code Review Summary

Fix Candidates

Code Review - PR #36369

Independent Assessment

Reconciliation with PR Narrative

Prior Review Reconciliation

Blast Radius Assessment

CI Status

Findings

Failure-Mode Probing

Verdict: NEEDS_DISCUSSION

Fix Candidates

Cross-Pollination

Test Command Used for Candidates

Candidate Artifacts

Comparative Fix Report — PR #36369

Candidates

Winning candidate

Notes

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