🤖 AI Summary

📊 Expand Full Review
🔍 Pre-Flight — Context & Validation
📝 Review Session — added ios26 image. · 9fe943f
Issue: #33770 - [iOS 26] CarouselView does not scroll to the correct last item Platforms Affected: iOS 26 only (confirmed working on iOS 18) Files Changed: 1 implementation file, 1 snapshot image

Issue Summary

CarouselView fails to scroll to the last item on iOS 26 when using programmatic navigation (Position or CurrentItem). Clicking "Go to LastItem" navigates to the next item instead of the last item. Confirmed iOS 26- does not reproduce on iOS 18. Validated by Syncfusion (partner) contributor.specific

Root Cause (from PR description)

iOS 26 changed the behavior of UICollectionView.ScrollToItem() to fire intermediate scroll position callbacks during animation, whereas iOS 18 only fired callbacks at the start and end. These intermediate callbacks trigger MapPosition in the handler, which calls UpdateFromPosition() again with incorrect intermediate position values, interrupting the original scroll to the target position.

Files Changed

• Fix: src/Controls/src/Core/Handlers/Items2/iOS/CarouselViewController2.cs (+15/-2)

  • Changed UpdateFromPosition() to async void
  • Added OperatingSystem.IsIOSVersionAtLeast(26) guard
  • Adds 200ms Task.Delay().ContinueWith() + MainThread.BeginInvokeOnMainThread() debounce pattern

• Snapshot: src/Controls/tests/TestCases.iOS.Tests/snapshots/ios-26/CarouselViewShouldScrollToRightPosition.png (updated baseline)

Reviewer Feedback (Copilot automated review)

File:Line Issue Status
CarouselViewController2.cs:567 Stale state risk: closure captures carouselPosition/currentItemPosition before delay; no re-validation after INVESTIGATE 200ms
CarouselViewController2.cs:562 200ms delay is arbitrary, no documentation/comment explaining INVESTIGATE choice
CarouselViewController2.cs:560 Missing MacCatalyst 26 check (pattern in codebase: CarouselViewController2.cs:540 async voidlacks exception handling - unhandled exceptions crash the INVESTIGATE appCarouselViewController2.cs:568` Race condition: multiple rapid calls create multiple delayed tasks executing INVESTIGATE concurrently

Existing Tests

• CarouselViewShouldScrollToRightPosition (Issue17283.cs) - screenshot test for scrolling to right position, iOS/Android/Mac
• CarouselViewiOSCrashPreventionTest (Issue16020.cs) - navigates to last item, all platforms

Fix Candidates

Source Approach Test Result Files Changed Notes

PR PR #34013 200ms debounce delay on iOS 26+ via async PENDING (Gate) CarouselViewController2.cs (+15/-2) Original PR void
🚦 Gate — Test Verification
📝 Review Session — added ios26 image. · 9fe943f
** FAILEDResult:** Platform: ios Mode: Full Verification

• Tests FAIL without (tests does not detect the bug)PASSED fix
• Tests PASS with fix

Analysis

The Gate failure is explained by the snapshot test structure:

1. The PR updates both CarouselViewController2.cs (code fix) AND ios-26/CarouselViewShouldScrollToRightPosition.png (updated snapshot baseline).
2. When the verification script reverts the fix files, it also reverts the snapshot baseline to the old (incorrect) image.
   PASS.

Root Cause of Gate Failure: The existing tests use screenshot comparison (VerifyScreenshot()). The PR updated the snapshot as part of the fix, which means reverting the fix also reverts the "expected" snapshot, making the test pass regardless of whether the fix is present.

What's Needed: The tests need to include a non-visual assertion (e.g., checking the current item index or label text) that would fail when the wrong item is shown, independent of snapshot comparison.

🔧 Fix — Analysis & Comparison
📝 Review Session — added ios26 image. · 9fe943f

Fix Candidates

Source Approach Test Result Files Changed Notes

PR PR #34013 200ms debounce delay on iOS 26+ via async void PASS (Gate - with fix) CarouselViewController2.cs (+15/-2) Original PR
Exhausted: N/A ( Gate failed, Fix phase not executed)skipped Selected Fix: PR's Gate confirmed tests pass with the fix, but tests don't catch the bug without itfix Skipped Reason: Gate failed (tests don't detect the bug). Fix phase skipped per workflow rules.

📋 Report — Final Recommendation
📝 Review Session — added ios26 image. · 9fe943f
Final Recommendation: REQUEST CHANGES##

Summary

PR #34013 fixes a real iOS 26-specific bug where CarouselView scrolls to the wrong item when navigating programmatically. The root cause analysis and fix approach are sound. However, the Gate phase failed because the existing tests don't actually detect the the PR's snapshot update is bundled with the code fix, making the test pass regardless of whether the fix is present.bug

Additionally, the fix has several code quality concerns raised by Copilot automated review that should be addressed before merge.

Root Cause

UpdateFromPosition() with stale intermediate position values, interrupting the scroll to the intended position.

Fix Quality

The fix works (tests pass with fix), but has the following concerns:

UpdateFromPosition() captures carouselPosition and currentItemPosition before the 200ms delay. If called multiple times rapidly (which is exactly what iOS 26 does), multiple delayed tasks execute concurrently with potentially stale values. The last one to fire wins unpredictably. A CancellationTokenSource debounce pattern should be used instead.**1.

The 200ms delay can span view disposal, navigation away, or ItemsSource changes. There's no re-validation inside the MainThread.BeginInvokeOnMainThread callback. Compare with UpdateInitialPosition() (line 602) which validates IsViewLoaded, ItemsSource, and ItemCount inside its callback. UpdateFromPosition should do the same.**2.

Other iOS 26 workarounds in the codebase consistently use:**3.

OperatingSystem.IsIOSVersionAtLeast(26) || OperatingSystem.IsMacCatalystVersionAtLeast(26)

This fix only checks iOS 26. If the same UICollectionView behavior change applies to MacCatalyst 26, it will remain broken there.

** async void Lacks Exception Handling (Medium)** 4. async void methods swallow exceptions into the synchronization context, potentially crashing the app. The method should either wrap the body in try/catch or be restructured.

** Tests Don't Catch the Bug (High)** 5. The existing CarouselViewShouldScrollToRightPosition test is a snapshot test. Since the PR also updates the snapshot file, reverting the fix also reverts the "expected" making the test pass against broken behavior. A non-visual assertion (e.g., checking GoToLastItem results in the correct item index or label text) is needed.image

Suggested Changes

1. Fix race condition: Use a CancellationTokenSource field to cancel any pending delayed scroll on each new call
2. Add state re-validation: Inside the MainThread.BeginInvokeOnMainThread callback, re-read the current state (re-check InitialPositionSet, ItemsView, ItemsSource, and re-compute position)
3. Add MacCatalyst 26 check: Update the condition to include || OperatingSystem.IsMacCatalystVersionAtLeast(26) (if applicable)
4. Add exception handling: Wrap the async body in try/catch
5. Strengthen tests: Add an assertion that verifies the correct item/position after navigation (e.g., verify the visible item label is "5" or the position equals the expected index)

References

• Issue: [iOS 26] CarouselView does not scroll to the correct last item #33770
• Comparison: UpdateInitialPosition() pattern at line this is the right template to follow602

📋 Expand PR Finalization Review

• Fixed the race condition by introducing a CancellationTokenSource to cancel any pending delayed scroll.
• Re-validated the current state inside the MainThread.BeginInvokeOnMainThread callback
• Wrapped the async logic in a try/catch block for safety.
• The Mac Catalyst–specific check is not required, as the current logic works correctly on both iOS and Mac Catalyst.
• Existing tests already cover the expected behavior and pass with this fix.

🚀 Dogfood this PR with:

⚠️ WARNING: Do not do this without first carefully reviewing the code of this PR to satisfy yourself it is safe.

curl -fsSL https://raw.githubusercontent.com/dotnet/maui/main/eng/scripts/get-maui-pr.sh | bash -s -- 34013

Or

• Run remotely in PowerShell:

iex "& { $(irm https://raw.githubusercontent.com/dotnet/maui/main/eng/scripts/get-maui-pr.ps1) } 34013"

🤖 AI Summary

📊 Expand Full Review
🔍 Pre-Flight — Context & Validation
📝 Review Session — Update CarouselViewController2.cs · 01be7b8
Issue: #33770 - [iOS 26] CarouselView does not scroll to the correct last item Platforms Affected: iOS 26 only (confirmed working on iOS 18) Files Changed: 1 implementation file, 1 snapshot image (tests NOT updated)

Issue Summary

CarouselView fails to scroll to the last item on iOS 26 when using programmatic navigation (Position or CurrentItem). Clicking "Go to LastItem" button navigates to the next item instead of the last item. iOS 26-specific; does not occur on iOS 18.

Root Cause (from PR description)

iOS 26 changed the behavior of UICollectionView.ScrollToItem() to fire intermediate scroll position callbacks during animation. Whereas iOS 18 only fires at start/end, iOS 26 fires intermediate callbacks that trigger MapPosition in the handler, which calls UpdateFromPosition() again with incorrect intermediate position values, interrupting the original scroll.

Prior Agent Review (Session Feb 18, 2026)

• Pre-Flight COMPLETE:
• ** Tests don't detect the bug (snapshot test reverts with fix)FAILED Gate:**
• Fix: Skipped (Gate failed)
• Report: REQUEST Code quality concerns + tests don't catch bugCHANGES

Author Responses to Prior Review

Concern Status
Stale state capture before delay Re-validates state inside callback FIXED
200ms delay undocumented Added comment; reduced to 100ms FIXED
Race condition: multiple rapid calls Added CancellationTokenSource debounce FIXED
lacks exception handling Added catch (Exception) (silent)
MacCatalyst 26 check Author claims not needed REJECTED missing
Tests skip iOS 26 with Assert. NOT ADDRESSED Ignore

Files Changed

• Fix: src/Controls/src/Core/Handlers/Items2/iOS/CarouselViewController2.cs (+52/-2)

  • Changed UpdateFromPosition() to async void
  • Added CancellationTokenSource _scrollDebounce field
  • Added OperatingSystem.IsIOSVersionAtLeast(26) guard
  • 100ms debounce with CancellationToken to cancel previous calls
  • Re-validates state inside callback before scrolling
  • try/catch wraps the async body

• Snapshot: src/Controls/tests/TestCases.iOS.Tests/snapshots/ios-26/CarouselViewShouldScrollToRightPosition.png (new baseline)

CRITICAL TEST ISSUE

Both existing tests explicitly ignore/skip iOS 26:

// Issue17283.cs
if (App is AppiumIOSApp iosApp && HelperExtensions.IsIOS26OrHigher(iosApp))
{
    Assert.Ignore("Ignored due to CarouselView scroll item issue in iOS 26.");
}
// Issue16020. same guardcs 

The snapshot was added for ios-26/CarouselViewShouldScrollToRightPosition.png but the test that generates it is still being ignored on iOS 26. The Assert.Ignore guards must be removed now that the fix is present.

Fix Candidates

Source Approach Test Result Files Changed Notes

PR PR #34013 CancellationTokenSource debounce (100ms) + state re-validation on iOS PENDING (Gate) CarouselViewController2.cs (+52/-2) Original PR - updated based on review 26+
🚦 Gate — Test Verification
📝 Review Session — Update CarouselViewController2.cs · 01be7b8
Result PASSED: Platform: ios Mode: Full Verification Test: CarouselViewShouldScrollToRightPosition (Issue17283)

• Tests FAIL without fix
• Tests PASS with fix

Details

• Build SDK: Microsoft.iOS.Sdk.net10.0_26.0 (iOS 26.0)
• Fix files reverted: CarouselViewController2.cs (and infrastructure files)
• Test duration: ~4 minutes 18 seconds
• Merge-base: c5fadf8

🔧 Fix — Analysis & Comparison
📝 Review Session — Update CarouselViewController2.cs · 01be7b8

Fix Candidates

Source Approach Test Result Files Changed Notes

1 try-fix bool flag, cleared in UpdateIsScrolling(false) PASS 1 file Simplest: ~10 lines, synchronous
2 try-fix , SetPosition rejects non-matching, cleared in ScrollAnimationEnded PASS 1 file Precise target tracking
3 try-fix Suppress MapPosition when carouselView.IsScrolling== FAIL 1 file Too broad: blocks user scroll position updates true
4 try-fix _nativePositionUpdateCount counter around FAIL 1 file Build env issue (VisualRegressionTester compile error) SetValueFromRenderer
5 try-fix counter + CollectionView.Layer.AnimationKeys stale check PASS 1 file Complex but stale-detection variant
6 try-fix UIView.Animate wrapper with ScrollToItem(animated:false) on iOS 26 PASS 1 file Prevents callbacks at source; hardcoded 0.3s duration +
7 try-fix Geometric expectedFinalOffsetX spatial filter via WillEndDragging PASS 2 files Spatial approach; modifies LayoutFactory2.cs
8 try-fix bool + CollectionView.Decelerating check + CommitCenteredPosition PASS 1 file Gesture-aware; distinguishes user vs programmatic scroll
9 try-fix MapPosition transaction gate in CarouselViewHandler2.iOS.cs, commit in ScrollAnimationEnded PASS 3 files Handler-level; modifies 3 files
10 try-fix in SetPosition rejects non-matching, commits in UpdateIsScrolling PASS 1 file Variant of Attempt 2
11 try-fix CATransaction CompletionBlock clears flag PASS 1 file Precise CA-based timing; ~16 lines
12 try-fix Temporarily nullify CollectionView.Delegate during scroll, restore in CATransaction PASS 1 file Most aggressive suppression; complex
13 try-fix _programmaticScrollTarget=-1 defer in UpdateFromPosition, commit in FAIL 1 file Build env issue (VisualRegressionTester compile error) UpdateIsScrolling
14 try-fix SetContentOffset(targetOffset, animated:true) to bypass ScrollToItem on iOS 18 PASS 1 file Bypasses ScrollToItem; iOS 18+ scope too broad; uses FlowLayout assumption +
PR PR #34013 async void + CancellationTokenSource 100ms debounce + state re-validation on iOS 26 PASS (Gate) 1 file, 1 snapshot Original PR +
Exhausted: Yes (3 cross-pollination rounds; all 5 models confirmed NO NEW IDEAS)

Selected Fix: PR's fix

Reason: The PR's fix (after the author's revisions addressing the prior agent review) is the most defensively robust:

• CancellationTokenSource correctly handles rapid successive calls (cancels the previous pending delay when a new call comes in)
• 100ms delay matches the existing UpdateInitialPosition pattern in the same class
• State re-validation inside the callback (re-checks InitialPositionSet, ItemsView, ItemsSource) prevents stale-state operations
• try/catch prevents app crashes from async void exceptions

Simpler alternatives (Attempts 1, 11) are viable but trade defensive robustness for brevity. For a high-traffic callback path on iOS 26+ where rapid calls are the exact problem being fixed, the CancellationTokenSource approach is more appropriate.

Remaining issue: The tests still have Assert.Ignore guards for iOS 26, which means the test suite won't verify the fix in CI on iOS 26. The PR must remove these guards.

📋 Report — Final Recommendation
📝 Review Session — Update CarouselViewController2.cs · 01be7b8
Final Recommendation: REQUEST CHANGES##

Summary

PR #34013 correctly identifies and addresses a real iOS 26-specific bug in CarouselView where UICollectionView.ScrollToItem() fires intermediate scroll position callbacks that interrupt programmatic navigation to the last item. The code fix quality has been significantly improved from the initial submission (author addressed all prior review feedback with CancellationTokenSource, state re-validation, documentation, and try/catch). Gate ** tests correctly detect the bug on iOS 26.PASSED**

However, two issues require changes before merge:

1. Tests still skip iOS Both existing tests have Assert.Ignore guards for iOS 26 that were never removed. The snapshot added by this PR will never be used in CI.26
2. CancellationTokenSource is never Memory/resource leak risk.disposed

Root Cause

a new competing ScrollToItem() call, resulting in the wrong item being displayed.

Fix Quality

The PR's CancellationTokenSource debounce approach is defensively correct for this use case:

• Each new UpdateFromPosition() call cancels the previous 100ms delay, ensuring only the final position update fires
• State re-validation inside the callback prevents operating on stale views
• Matches the existing UpdateInitialPosition() pattern (also uses 100ms delay)
• try/catch prevents async void exceptions from crashing the app

11 alternative fixes were explored across 3 cross-pollination rounds. All 9 simpler alternatives (bool flags, counters, UIView.Animate, geometric filter, gesture state, CATransaction, SetContentOffset) passed tests. The simplest alternative (Attempt 1: _isScrollingProgrammatically bool flag, ~10 lines) is viable but trades defensive robustness for brevity. The PR's approach is more robust for rapid successive callbacks, which is the exact scenario causing this bug.

Issues Found

** Both tests referenced in the PR have Assert.Ignore guards that skip execution on iOS 26:

// Issue17283.cs line 22- MUST REMOVE:25 
if (App is AppiumIOSApp iosApp && HelperExtensions.IsIOS26OrHigher(iosApp))
{
    Assert.Ignore("Ignored due to CarouselView scroll item issue in iOS 26.");
}

// Issue16020. same  MUST REMOVEguard cs 

These guards were added before this fix to prevent CI failures from the known bug. Now that the fix is present, they must be removed so the tests actually run on iOS 26 and validate the fix going forward. The ios-26/CarouselViewShouldScrollToRightPosition.png snapshot added by this PR will never be compared in CI until these guards are removed.

Required changes:

• src/Controls/tests/TestCases.Shared.Tests/Tests/Issues/Issue17283. remove the IsIOS26OrHigher guard blockcs
• src/Controls/tests/TestCases.Shared.Tests/Tests/Issues/Issue16020. remove the IsIOS26OrHigher guard blockcs

** The _scrollDebounce field accumulates a new CancellationTokenSource on every UpdateFromPosition() call. The previous one is cancelled but not disposed. This should be:

_scrollDebounce?.Cancel();
_scrollDebounce?.Dispose();  // ADD THIS
_scrollDebounce = new CancellationTokenSource();

And in TearDown/disconnect:

_scrollDebounce?.Cancel();
_scrollDebounce?.Dispose();
_scrollDebounce = null;

** [iOS26] should be [iOS 26] with a space (consistent with issue labels like version/iOS-26).

**

• CancellationTokenSource prevents race conditions from rapid calls
• State re-validation inside callback (re-checks InitialPositionSet, ItemsView, ItemsSource)
• try/catch wraps async void body
• Comment explains the 100ms delay choice
• Delay reduced from 200ms to 100ms (matching UpdateInitialPosition)

Alternative Fix Considered

The simplest validated alternative (Attempt 1, _isScrollingProgrammatically bool flag):

• ~10 lines vs ~50 lines in the PR
• Synchronous, no timing dependency
• However: doesn't handle rapid successive calls as robustly as CancellationTokenSource

Selected Fix: PR's more robust for the specific problem (rapid intermediate callbacks). The PR's approach is appropriate; the required changes are removing the Assert.Ignore guards and disposing CancellationTokenSource.fix

What NOT to Do (for future agents)

Don't suppress MapPosition when carouselView.IsScrolling == IsScrolling is true for ALL scrolling (user + programmatic), blocking legitimate user-initiated position updatestrue - Don't use SetContentOffset with UICollectionViewFlowLayout CarouselView2 uses compositional layout, not FlowLayoutassumptions - Don't assume the snapshot validates the always check that the test body actually RUNS on the target OS version (Assert.Ignore guards can silently bypass test execution)fix -

References

• Issue: [iOS 26] CarouselView does not scroll to the correct last item #33770
• Pattern reference: UpdateInitialPosition() at line 615 (same 100ms pattern, same validation structure)

📋 Expand PR Finalization Review

Fixed the memory leak by overriding Dispose in CarouselViewController2 to properly cancel and dispose of _scrollDebounce when the view controller is disposed. No other major concerns.

/azp run maui-pr-uitests , maui-pr-devicetests

🤖 AI Summary

🤖 AI Summary

📊 Expand Full Review — cc4e585 · Addressed concerns.
🔍 Pre-Flight — Context & Validation
Issue: #33770 - [iOS 26] CarouselView does not scroll to the correct last item PR: #34013 - [iOS26] Fix CarouselView scrolling to wrong item when navigating to last item Platforms Affected: iOS 26 Files Changed: 1 implementation, 2 API baseline, 1 test snapshot asset

Key Findings

• The linked issue is explicitly iOS 26-specific and was validated by MAUI team members as reproducing on iOS 26 but not iOS 18.
• The PR changes src/Controls/src/Core/Handlers/Items2/iOS/CarouselViewController2.cs, adds Dispose(bool) API entries to the iOS and MacCatalyst PublicAPI baselines, and updates an iOS 26 snapshot image; it does not add or modify executable tests.
• The PR description attributes the bug to iOS 26 UICollectionView.ScrollToItem() emitting intermediate callbacks that retrigger UpdateFromPosition() with transient positions during animation.
• Prior agent-review history on the PR shows an earlier round of concerns around stale captured state, arbitrary delay, exception handling, and concurrent delayed callbacks; the author responded by adding cancellation-token debouncing, callback-time state revalidation, a comment explaining the delay, and Dispose(bool) cleanup.
• Review discussion still includes an unresolved product question about whether the iOS 26 workaround should also be gated for MacCatalyst 26; the author stated the extra check was unnecessary.
• Because only a snapshot asset changed on the test side, Gate needs to confirm that the existing tests actually fail against a broken baseline rather than simply matching a reverted expected image.

Edge Cases / Discussion Notes

• The issue is reported as iOS 26-only and explicitly non-reproducible on iOS 18.
• Prior review feedback questioned MacCatalyst 26 behavior; current PR discussion says the fix works there without an explicit MacCatalyst version check.
• The PR body says existing tests already cover the scenario, so Gate must validate that claim directly.

Fix Candidates

Source Approach Test Result Files Changed Notes

PR PR #34013 Debounce iOS 26 UpdateFromPosition() with cancellable 100ms delay, then re-read state on main thread before ScrollToPosition; add Dispose(bool) PENDING (Gate) src/Controls/src/Core/Handlers/Items2/iOS/CarouselViewController2.cs, src/Controls/src/Core/PublicAPI/net-ios/PublicAPI.Unshipped.txt, src/Controls/src/Core/PublicAPI/net-maccatalyst/PublicAPI.Unshipped.txt, src/Controls/tests/TestCases.iOS.Tests/snapshots/ios-26/CarouselViewShouldScrollToRightPosition.png Original PR; executable tests were not modified cleanup
🚦 Gate — Test Verification

Gate FAILEDResult:

Platform: ios Mode: Full Verification Verification Agent: verify-tests-fail-without-fix via task agent Test Filter Used by verifier: CarouselView

• Tests FAIL without fix:
• Tests PASS with fix:

Notes

• The isolated verification run reported that the iOS CarouselView test set passed on both the broken baseline and the PR state.
• The two issue-specific tests associated with issue [iOS 26] CarouselView does not scroll to the correct last item #33770, Issue17283.CarouselViewShouldScrollToRightPosition and Issue16020.CarouselViewiOSCrashPreventionTest, currently contain Assert.Ignore(...) guards on iOS 26, so they do not validate the bug on the affected platform.
• Because the relevant tests are skipped and the broader CarouselView suite still passes without the fix, current coverage does not prove that PR [iOS26] Fix CarouselView scrolling to wrong item when navigating to last item #34013 catches issue [iOS 26] CarouselView does not scroll to the correct last item #33770.

🔧 Fix — Analysis & Comparison

Fix Candidates

Source Approach Test Result Files Changed Notes

1 try-fix (claude-opus-4.6) Programmatic-scroll guard flag that ignores re-entrant UpdateFromPosition during animated programmatic scroll and clears on ScrollAnimationEnded PASS 2 files Deterministic lifecycle guard; no async, timer, or version gate
2 try-fix (claude-sonnet-4.6) In-flight target-position guard that suppresses duplicate re-entry while already animating to the same target PASS 1 file More selective than attempt 1; still synchronous and delay-free
3 try-fix (gpt-5.3-codex) End-of-animation position commit that suppresses intermediate callback-driven position updates and commits once scrolling ends PASS 1 file Passed after one transient Appium retry; artifacts landed in attempt-4
4 try-fix (gemini-3-pro-preview) Suppress intermediate Scrolled propagation during animated programmatic scroll while keeping offsets in sync FAIL 2 files Failed validation due repeated suite instability and unrelated CarouselView failure
5 try-fix (round 2 new idea) Use non-animated scroll for iOS 26 multi-item or last-item programmatic jumps, then explicitly SetPosition PASS 1 file Smallest passing alternative; avoids intermediate callbacks entirely
6 try-fix (round 2 new idea) Use geometry-based ScrollRectToVisible navigation via layout attributes and re-enable the two iOS 26 issue tests PASS 3 files Only candidate that also makes the skipped issue-specific tests run on iOS 26
7 try-fix (round 3 new idea) Wrap ScrollToItem in PerformBatchUpdates to force collection-view synchronization before scrolling FAIL 1 file Timed out on the relevant scenario and introduced broader instability
PR PR #34013 Cancellable 100ms debounce in UpdateFromPosition on iOS 26, with callback-time state revalidation and Dispose cleanup PASS (with fix), but gate coverage invalid 4 files Existing issue-specific tests are still skipped on iOS 26

Cross-Pollination

Model Round New Ideas? Details
claude-opus-4.6 2 No NO NEW IDEAS
claude-sonnet-4.6 2 Yes Use non-animated programmatic scroll for multi-item jumps or last-item jumps, then explicitly set final index
gpt-5.3-codex 2 No NO NEW IDEAS
gemini-3-pro-preview 2 Yes Use ScrollRectToVisible with the target item's frame from layout attributes instead of ScrollToItem
claude-opus-4.6 3 No NO NEW IDEAS
claude-sonnet-4.6 3 No NO NEW IDEAS
gpt-5.3-codex 3 No NO NEW IDEAS
gemini-3-pro-preview 3 Yes Wrap scroll in PerformBatchUpdates to synchronize layout and data-source state before scrolling
Exhausted: Yes (3 cross-pollination rounds completed) Selected Fix: Candidate #6 - it is the only empirically passing alternative that also closes the current gate coverage gap by re-enabling Issue16020 and Issue17283 on iOS 26, making it the strongest merge-ready option among the explored candidates.

📋 Report — Final Recommendation

Final Recommendation: REQUEST CHANGES

Phase Status

Phase Status Notes
Pre-Flight COMPLETE Issue #33770 is iOS 26-specific; PR updates one iOS handler, two PublicAPI baselines, and one iOS-26 snapshot asset.
Gate FAILED Current iOS verification does not prove the bug is caught because the two issue-specific tests still Assert.Ignore on iOS 26.
Try-Fix COMPLETE 7 empirically tested alternatives (5 pass, 2 fail) across 3 cross-pollination rounds.
Report COMPLETE Final recommendation written.

Summary

PR #34013 addresses a plausible iOS 26 CarouselView regression and the current implementation is more defensively coded than the initial submission. However, the PR is not ready to approve because the current test story is still insufficient on the affected platform: Issue17283.CarouselViewShouldScrollToRightPosition and Issue16020.CarouselViewiOSCrashPreventionTest remain skipped on iOS 26, so Gate could not verify fail-without-fix and pass-with-fix on the scenario the PR claims to solve.

Try-fix exploration found multiple passing alternatives. The strongest explored option was Candidate #6, which replaced the ScrollToItem path with geometry-based ScrollRectToVisible navigation and re-enabled the two iOS 26 issue tests; that candidate passed validation and is the only explored option that also fixes the current gate-coverage gap.

Root Cause

The issue is consistent with iOS 26 UICollectionView behavior emitting intermediate callbacks during animated programmatic scrolling. Those transient positions feed back into MAUI's position synchronization path (MapPosition and UpdateFromPosition) and can redirect the carousel before the original scroll reaches the intended final item.

Fix Quality

The PR's current debounce-based fix is serviceable, but it is not the best merge-ready outcome from this review because it leaves the relevant iOS 26 tests disabled. A reviewable fix for this issue needs to do both of the following:

• resolve the iOS 26 scrolling behavior, and
• allow the affected iOS 26 issue tests to execute so the bug is actually covered in CI.

Requested Changes

• Re-enable Issue17283.CarouselViewShouldScrollToRightPosition and Issue16020.CarouselViewiOSCrashPreventionTest on iOS 26 so Gate can validate the bug directly.
• Prefer a fix approach that removes the need for timing-based debounce if possible. Candidate [Spec] Transitions #6 from try-fix is the strongest explored alternative because it passed while also enabling the skipped issue tests.
• If the debounce-based PR fix is retained, it still needs accompanying test changes that make the iOS 26 scenario run rather than skip.

📋 Expand PR Finalization Review

The suggested fix does not resolve the CarouselViewShouldScrollToRightPosition test, so I have only enabled both tests with the current PR changes.

🚦 Gate - Test Before and After Fix

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  ##vso[build.updatebuildnumber]10.0.60-ci+azdo.13763453
  Graphics -> /Users/cloudtest/vss/_work/1/s/artifacts/bin/Graphics/Debug/net10.0-ios26.0/Microsoft.Maui.Graphics.dll
  ##vso[build.updatebuildnumber]10.0.60-ci+azdo.13763453
  Essentials -> /Users/cloudtest/vss/_work/1/s/artifacts/bin/Essentials/Debug/net10.0-ios26.0/Microsoft.Maui.Essentials.dll
  ##vso[build.updatebuildnumber]10.0.60-ci+azdo.13763453
  Core -> /Users/cloudtest/vss/_work/1/s/artifacts/bin/Core/Debug/net10.0-ios26.0/Microsoft.Maui.dll
  ##vso[build.updatebuildnumber]10.0.60-ci+azdo.13763453
  Maps -> /Users/cloudtest/vss/_work/1/s/artifacts/bin/Maps/Debug/net10.0-ios26.0/Microsoft.Maui.Maps.dll
  Controls.BindingSourceGen -> /Users/cloudtest/vss/_work/1/s/artifacts/bin/Controls.BindingSourceGen/Debug/netstandard2.0/Microsoft.Maui.Controls.BindingSourceGen.dll
  ##vso[build.updatebuildnumber]10.0.60-ci+azdo.13763453
  Controls.Core -> /Users/cloudtest/vss/_work/1/s/artifacts/bin/Controls.Core/Debug/net10.0-ios26.0/Microsoft.Maui.Controls.dll
  ##vso[build.updatebuildnumber]10.0.60-ci+azdo.13763453
  ##vso[build.updatebuildnumber]10.0.60-ci+azdo.13763453
  ##vso[build.updatebuildnumber]10.0.60-ci+azdo.13763453
  Controls.Maps -> /Users/cloudtest/vss/_work/1/s/artifacts/bin/Controls.Maps/Debug/net10.0-ios26.0/Microsoft.Maui.Controls.Maps.dll
  Controls.Foldable -> /Users/cloudtest/vss/_work/1/s/artifacts/bin/Controls.Foldable/Debug/net10.0-ios26.0/Microsoft.Maui.Controls.Foldable.dll
  ##vso[build.updatebuildnumber]10.0.60-ci+azdo.13763453
  Controls.Xaml -> /Users/cloudtest/vss/_work/1/s/artifacts/bin/Controls.Xaml/Debug/net10.0-ios26.0/Microsoft.Maui.Controls.Xaml.dll
  Microsoft.AspNetCore.Components.WebView.Maui -> /Users/cloudtest/vss/_work/1/s/artifacts/bin/Microsoft.AspNetCore.Components.WebView.Maui/Debug/net10.0-ios26.0/Microsoft.AspNetCore.Components.WebView.Maui.dll
  Detected signing identity:
    Code Signing Key: "" (-)
    Provisioning Profile: "" () - no entitlements
    Bundle Id: com.microsoft.maui.uitests
    App Id: com.microsoft.maui.uitests
  Controls.TestCases.HostApp -> /Users/cloudtest/vss/_work/1/s/artifacts/bin/Controls.TestCases.HostApp/Debug/net10.0-ios/iossimulator-arm64/Controls.TestCases.HostApp.dll
  Optimizing assemblies for size may change the behavior of the app. Be sure to test after publishing. See: https://aka.ms/dotnet-illink
  Optimizing assemblies for size. This process might take a while.

Build succeeded.

/Users/cloudtest/vss/_work/1/s/.dotnet/packs/Microsoft.iOS.Sdk.net10.0_26.0/26.0.11017/targets/Xamarin.Shared.Sdk.targets(309,3): warning : RuntimeIdentifier was set on the command line, and will override the value for RuntimeIdentifiers set in the project file. [/Users/cloudtest/vss/_work/1/s/src/Controls/tests/TestCases.HostApp/Controls.TestCases.HostApp.csproj::TargetFramework=net10.0-ios]
    1 Warning(s)
    0 Error(s)

Time Elapsed 00:01:40.87
  Determining projects to restore...
  Restored /Users/cloudtest/vss/_work/1/s/src/TestUtils/src/UITest.Core/UITest.Core.csproj (in 711 ms).
  Restored /Users/cloudtest/vss/_work/1/s/src/Controls/src/BindingSourceGen/Controls.BindingSourceGen.csproj (in 711 ms).
  Restored /Users/cloudtest/vss/_work/1/s/src/Graphics/src/Graphics/Graphics.csproj (in 711 ms).
  Restored /Users/cloudtest/vss/_work/1/s/src/TestUtils/src/VisualTestUtils/VisualTestUtils.csproj (in 711 ms).
  Restored /Users/cloudtest/vss/_work/1/s/src/Controls/tests/CustomAttributes/Controls.CustomAttributes.csproj (in 647 ms).
  Restored /Users/cloudtest/vss/_work/1/s/src/Controls/src/Core/Controls.Core.csproj (in 767 ms).
  Restored /Users/cloudtest/vss/_work/1/s/src/Core/src/Core.csproj (in 784 ms).
  Restored /Users/cloudtest/vss/_work/1/s/src/Essentials/src/Essentials.csproj (in 10 ms).
  Restored /Users/cloudtest/vss/_work/1/s/src/TestUtils/src/UITest.NUnit/UITest.NUnit.csproj (in 4.34 sec).
  Restored /Users/cloudtest/vss/_work/1/s/src/TestUtils/src/UITest.Appium/UITest.Appium.csproj (in 4.71 sec).
  Restored /Users/cloudtest/vss/_work/1/s/src/TestUtils/src/UITest.Analyzers/UITest.Analyzers.csproj (in 5.33 sec).
  Restored /Users/cloudtest/vss/_work/1/s/src/TestUtils/src/VisualTestUtils.MagickNet/VisualTestUtils.MagickNet.csproj (in 3.66 sec).
  Restored /Users/cloudtest/vss/_work/1/s/src/Controls/tests/TestCases.iOS.Tests/Controls.TestCases.iOS.Tests.csproj (in 5.68 sec).
  ##vso[build.updatebuildnumber]10.0.60-ci+azdo.13763453
  Controls.CustomAttributes -> /Users/cloudtest/vss/_work/1/s/artifacts/bin/Controls.CustomAttributes/Debug/net10.0/Controls.CustomAttributes.dll
  Graphics -> /Users/cloudtest/vss/_work/1/s/artifacts/bin/Graphics/Debug/net10.0/Microsoft.Maui.Graphics.dll
  ##vso[build.updatebuildnumber]10.0.60-ci+azdo.13763453
  Essentials -> /Users/cloudtest/vss/_work/1/s/artifacts/bin/Essentials/Debug/net10.0/Microsoft.Maui.Essentials.dll
  ##vso[build.updatebuildnumber]10.0.60-ci+azdo.13763453
  Core -> /Users/cloudtest/vss/_work/1/s/artifacts/bin/Core/Debug/net10.0/Microsoft.Maui.dll
  Controls.BindingSourceGen -> /Users/cloudtest/vss/_work/1/s/artifacts/bin/Controls.BindingSourceGen/Debug/netstandard2.0/Microsoft.Maui.Controls.BindingSourceGen.dll
  ##vso[build.updatebuildnumber]10.0.60-ci+azdo.13763453
  Controls.Core -> /Users/cloudtest/vss/_work/1/s/artifacts/bin/Controls.Core/Debug/net10.0/Microsoft.Maui.Controls.dll
  UITest.Core -> /Users/cloudtest/vss/_work/1/s/artifacts/bin/UITest.Core/Debug/net10.0/UITest.Core.dll
  VisualTestUtils -> /Users/cloudtest/vss/_work/1/s/artifacts/bin/VisualTestUtils/Debug/netstandard2.0/VisualTestUtils.dll
  UITest.NUnit -> /Users/cloudtest/vss/_work/1/s/artifacts/bin/UITest.NUnit/Debug/net10.0/UITest.NUnit.dll
  VisualTestUtils.MagickNet -> /Users/cloudtest/vss/_work/1/s/artifacts/bin/VisualTestUtils.MagickNet/Debug/netstandard2.0/VisualTestUtils.MagickNet.dll
  UITest.Appium -> /Users/cloudtest/vss/_work/1/s/artifacts/bin/UITest.Appium/Debug/net10.0/UITest.Appium.dll
  UITest.Analyzers -> /Users/cloudtest/vss/_work/1/s/artifacts/bin/UITest.Analyzers/Debug/netstandard2.0/UITest.Analyzers.dll
  Controls.TestCases.iOS.Tests -> /Users/cloudtest/vss/_work/1/s/artifacts/bin/Controls.TestCases.iOS.Tests/Debug/net10.0/Controls.TestCases.iOS.Tests.dll
Test run for /Users/cloudtest/vss/_work/1/s/artifacts/bin/Controls.TestCases.iOS.Tests/Debug/net10.0/Controls.TestCases.iOS.Tests.dll (.NETCoreApp,Version=v10.0)
VSTest version 18.0.1 (arm64)

Starting test execution, please wait...
A total of 1 test files matched the specified pattern.
/Users/cloudtest/vss/_work/1/s/artifacts/bin/Controls.TestCases.iOS.Tests/Debug/net10.0/Controls.TestCases.iOS.Tests.dll
[xUnit.net 00:00:00.00] xUnit.net VSTest Adapter v2.8.2+699d445a1a (64-bit .NET 10.0.0)
[xUnit.net 00:00:00.04]   Discovering: Controls.TestCases.iOS.Tests
[xUnit.net 00:00:00.13]   Discovered:  Controls.TestCases.iOS.Tests
NUnit Adapter 4.5.0.0: Test execution started
Running selected tests in /Users/cloudtest/vss/_work/1/s/artifacts/bin/Controls.TestCases.iOS.Tests/Debug/net10.0/Controls.TestCases.iOS.Tests.dll
   NUnit3TestExecutor discovered 1 of 1 NUnit test cases using Current Discovery mode, Non-Explicit run
>>>>> 4/7/2026 3:08:58 AM FixtureSetup for Issue16020(iOS)
>>>>> 4/7/2026 3:09:02 AM CarouselViewiOSCrashPreventionTest Start
>>>>> 4/7/2026 3:09:05 AM CarouselViewiOSCrashPreventionTest Stop
  Passed CarouselViewiOSCrashPreventionTest [3 s]
NUnit Adapter 4.5.0.0: Test execution complete

Test Run Successful.
Total tests: 1
     Passed: 1
 Total time: 59.7039 Seconds

  Determining projects to restore...
  Restored /Users/cloudtest/vss/_work/1/s/src/Controls/src/BindingSourceGen/Controls.BindingSourceGen.csproj (in 296 ms).
  Restored /Users/cloudtest/vss/_work/1/s/src/Graphics/src/Graphics/Graphics.csproj (in 313 ms).
  Restored /Users/cloudtest/vss/_work/1/s/src/Essentials/src/Essentials.csproj (in 313 ms).
  Restored /Users/cloudtest/vss/_work/1/s/src/Controls/src/Core/Controls.Core.csproj (in 339 ms).
  Restored /Users/cloudtest/vss/_work/1/s/src/Core/src/Core.csproj (in 353 ms).
  6 of 11 projects are up-to-date for restore.
/Users/cloudtest/vss/_work/1/s/.dotnet/packs/Microsoft.iOS.Sdk.net10.0_26.0/26.0.11017/targets/Xamarin.Shared.Sdk.targets(309,3): warning : RuntimeIdentifier was set on the command line, and will override the value for RuntimeIdentifiers set in the project file. [/Users/cloudtest/vss/_work/1/s/src/Controls/tests/TestCases.HostApp/Controls.TestCases.HostApp.csproj::TargetFramework=net10.0-ios]
  ##vso[build.updatebuildnumber]10.0.60-ci+azdo.13763453
  Graphics -> /Users/cloudtest/vss/_work/1/s/artifacts/bin/Graphics/Debug/net10.0-ios26.0/Microsoft.Maui.Graphics.dll
  ##vso[build.updatebuildnumber]10.0.60-ci+azdo.13763453
  Essentials -> /Users/cloudtest/vss/_work/1/s/artifacts/bin/Essentials/Debug/net10.0-ios26.0/Microsoft.Maui.Essentials.dll
  ##vso[build.updatebuildnumber]10.0.60-ci+azdo.13763453
  Core -> /Users/cloudtest/vss/_work/1/s/artifacts/bin/Core/Debug/net10.0-ios26.0/Microsoft.Maui.dll
  ##vso[build.updatebuildnumber]10.0.60-ci+azdo.13763453
  Maps -> /Users/cloudtest/vss/_work/1/s/artifacts/bin/Maps/Debug/net10.0-ios26.0/Microsoft.Maui.Maps.dll
  Controls.BindingSourceGen -> /Users/cloudtest/vss/_work/1/s/artifacts/bin/Controls.BindingSourceGen/Debug/netstandard2.0/Microsoft.Maui.Controls.BindingSourceGen.dll
  ##vso[build.updatebuildnumber]10.0.60-ci+azdo.13763453
  Controls.Core -> /Users/cloudtest/vss/_work/1/s/artifacts/bin/Controls.Core/Debug/net10.0-ios26.0/Microsoft.Maui.Controls.dll
  ##vso[build.updatebuildnumber]10.0.60-ci+azdo.13763453
  ##vso[build.updatebuildnumber]10.0.60-ci+azdo.13763453
  ##vso[build.updatebuildnumber]10.0.60-ci+azdo.13763453
  ##vso[build.updatebuildnumber]10.0.60-ci+azdo.13763453
  Microsoft.AspNetCore.Components.WebView.Maui -> /Users/cloudtest/vss/_work/1/s/artifacts/bin/Microsoft.AspNetCore.Components.WebView.Maui/Debug/net10.0-ios26.0/Microsoft.AspNetCore.Components.WebView.Maui.dll
  Controls.Maps -> /Users/cloudtest/vss/_work/1/s/artifacts/bin/Controls.Maps/Debug/net10.0-ios26.0/Microsoft.Maui.Controls.Maps.dll
  Controls.Xaml -> /Users/cloudtest/vss/_work/1/s/artifacts/bin/Controls.Xaml/Debug/net10.0-ios26.0/Microsoft.Maui.Controls.Xaml.dll
  Controls.Foldable -> /Users/cloudtest/vss/_work/1/s/artifacts/bin/Controls.Foldable/Debug/net10.0-ios26.0/Microsoft.Maui.Controls.Foldable.dll
  Detected signing identity:
    Code Signing Key: "" (-)
    Provisioning Profile: "" () - no entitlements
    Bundle Id: com.microsoft.maui.uitests
    App Id: com.microsoft.maui.uitests
  Controls.TestCases.HostApp -> /Users/cloudtest/vss/_work/1/s/artifacts/bin/Controls.TestCases.HostApp/Debug/net10.0-ios/iossimulator-arm64/Controls.TestCases.HostApp.dll
  Optimizing assemblies for size may change the behavior of the app. Be sure to test after publishing. See: https://aka.ms/dotnet-illink
  Optimizing assemblies for size. This process might take a while.

Build succeeded.

/Users/cloudtest/vss/_work/1/s/.dotnet/packs/Microsoft.iOS.Sdk.net10.0_26.0/26.0.11017/targets/Xamarin.Shared.Sdk.targets(309,3): warning : RuntimeIdentifier was set on the command line, and will override the value for RuntimeIdentifiers set in the project file. [/Users/cloudtest/vss/_work/1/s/src/Controls/tests/TestCases.HostApp/Controls.TestCases.HostApp.csproj::TargetFramework=net10.0-ios]
    1 Warning(s)
    0 Error(s)

Time Elapsed 00:00:40.94
  Determining projects to restore...
  Restored /Users/cloudtest/vss/_work/1/s/src/Controls/src/BindingSourceGen/Controls.BindingSourceGen.csproj (in 475 ms).
  Restored /Users/cloudtest/vss/_work/1/s/src/Graphics/src/Graphics/Graphics.csproj (in 478 ms).
  Restored /Users/cloudtest/vss/_work/1/s/src/Essentials/src/Essentials.csproj (in 479 ms).
  Restored /Users/cloudtest/vss/_work/1/s/src/Controls/src/Core/Controls.Core.csproj (in 496 ms).
  Restored /Users/cloudtest/vss/_work/1/s/src/Core/src/Core.csproj (in 517 ms).
  8 of 13 projects are up-to-date for restore.
  Controls.CustomAttributes -> /Users/cloudtest/vss/_work/1/s/artifacts/bin/Controls.CustomAttributes/Debug/net10.0/Controls.CustomAttributes.dll
  ##vso[build.updatebuildnumber]10.0.60-ci+azdo.13763453
  Graphics -> /Users/cloudtest/vss/_work/1/s/artifacts/bin/Graphics/Debug/net10.0/Microsoft.Maui.Graphics.dll
  ##vso[build.updatebuildnumber]10.0.60-ci+azdo.13763453
  Essentials -> /Users/cloudtest/vss/_work/1/s/artifacts/bin/Essentials/Debug/net10.0/Microsoft.Maui.Essentials.dll
  ##vso[build.updatebuildnumber]10.0.60-ci+azdo.13763453
  Core -> /Users/cloudtest/vss/_work/1/s/artifacts/bin/Core/Debug/net10.0/Microsoft.Maui.dll
  Controls.BindingSourceGen -> /Users/cloudtest/vss/_work/1/s/artifacts/bin/Controls.BindingSourceGen/Debug/netstandard2.0/Microsoft.Maui.Controls.BindingSourceGen.dll
  ##vso[build.updatebuildnumber]10.0.60-ci+azdo.13763453
  Controls.Core -> /Users/cloudtest/vss/_work/1/s/artifacts/bin/Controls.Core/Debug/net10.0/Microsoft.Maui.Controls.dll
  UITest.Core -> /Users/cloudtest/vss/_work/1/s/artifacts/bin/UITest.Core/Debug/net10.0/UITest.Core.dll
  VisualTestUtils -> /Users/cloudtest/vss/_work/1/s/artifacts/bin/VisualTestUtils/Debug/netstandard2.0/VisualTestUtils.dll
  UITest.Appium -> /Users/cloudtest/vss/_work/1/s/artifacts/bin/UITest.Appium/Debug/net10.0/UITest.Appium.dll
  VisualTestUtils.MagickNet -> /Users/cloudtest/vss/_work/1/s/artifacts/bin/VisualTestUtils.MagickNet/Debug/netstandard2.0/VisualTestUtils.MagickNet.dll
  UITest.NUnit -> /Users/cloudtest/vss/_work/1/s/artifacts/bin/UITest.NUnit/Debug/net10.0/UITest.NUnit.dll
  UITest.Analyzers -> /Users/cloudtest/vss/_work/1/s/artifacts/bin/UITest.Analyzers/Debug/netstandard2.0/UITest.Analyzers.dll
  Controls.TestCases.iOS.Tests -> /Users/cloudtest/vss/_work/1/s/artifacts/bin/Controls.TestCases.iOS.Tests/Debug/net10.0/Controls.TestCases.iOS.Tests.dll
Test run for /Users/cloudtest/vss/_work/1/s/artifacts/bin/Controls.TestCases.iOS.Tests/Debug/net10.0/Controls.TestCases.iOS.Tests.dll (.NETCoreApp,Version=v10.0)
VSTest version 18.0.1 (arm64)

Starting test execution, please wait...
A total of 1 test files matched the specified pattern.
/Users/cloudtest/vss/_work/1/s/artifacts/bin/Controls.TestCases.iOS.Tests/Debug/net10.0/Controls.TestCases.iOS.Tests.dll
[xUnit.net 00:00:00.00] xUnit.net VSTest Adapter v2.8.2+699d445a1a (64-bit .NET 10.0.0)
[xUnit.net 00:00:00.04]   Discovering: Controls.TestCases.iOS.Tests
[xUnit.net 00:00:00.12]   Discovered:  Controls.TestCases.iOS.Tests
NUnit Adapter 4.5.0.0: Test execution started
Running selected tests in /Users/cloudtest/vss/_work/1/s/artifacts/bin/Controls.TestCases.iOS.Tests/Debug/net10.0/Controls.TestCases.iOS.Tests.dll
   NUnit3TestExecutor discovered 1 of 1 NUnit test cases using Current Discovery mode, Non-Explicit run
>>>>> 4/7/2026 3:11:49 AM FixtureSetup for Issue16020(iOS)
>>>>> 4/7/2026 3:11:52 AM CarouselViewiOSCrashPreventionTest Start
>>>>> 4/7/2026 3:11:57 AM CarouselViewiOSCrashPreventionTest Stop
  Passed CarouselViewiOSCrashPreventionTest [4 s]
NUnit Adapter 4.5.0.0: Test execution complete

Test Run Successful.
Total tests: 1
     Passed: 1
 Total time: 19.4313 Seconds

  Determining projects to restore...
  Restored /Users/cloudtest/vss/_work/1/s/src/Controls/src/BindingSourceGen/Controls.BindingSourceGen.csproj (in 339 ms).
  Restored /Users/cloudtest/vss/_work/1/s/src/Graphics/src/Graphics/Graphics.csproj (in 357 ms).
  Restored /Users/cloudtest/vss/_work/1/s/src/Essentials/src/Essentials.csproj (in 358 ms).
  Restored /Users/cloudtest/vss/_work/1/s/src/Controls/src/Core/Controls.Core.csproj (in 396 ms).
  Restored /Users/cloudtest/vss/_work/1/s/src/Core/src/Core.csproj (in 410 ms).
  6 of 11 projects are up-to-date for restore.
/Users/cloudtest/vss/_work/1/s/.dotnet/packs/Microsoft.iOS.Sdk.net10.0_26.0/26.0.11017/targets/Xamarin.Shared.Sdk.targets(309,3): warning : RuntimeIdentifier was set on the command line, and will override the value for RuntimeIdentifiers set in the project file. [/Users/cloudtest/vss/_work/1/s/src/Controls/tests/TestCases.HostApp/Controls.TestCases.HostApp.csproj::TargetFramework=net10.0-ios]
  ##vso[build.updatebuildnumber]10.0.60-ci+azdo.13763453
  Graphics -> /Users/cloudtest/vss/_work/1/s/artifacts/bin/Graphics/Debug/net10.0-ios26.0/Microsoft.Maui.Graphics.dll
  ##vso[build.updatebuildnumber]10.0.60-ci+azdo.13763453
  Essentials -> /Users/cloudtest/vss/_work/1/s/artifacts/bin/Essentials/Debug/net10.0-ios26.0/Microsoft.Maui.Essentials.dll
  ##vso[build.updatebuildnumber]10.0.60-ci+azdo.13763453
  Core -> /Users/cloudtest/vss/_work/1/s/artifacts/bin/Core/Debug/net10.0-ios26.0/Microsoft.Maui.dll
  ##vso[build.updatebuildnumber]10.0.60-ci+azdo.13763453
  Maps -> /Users/cloudtest/vss/_work/1/s/artifacts/bin/Maps/Debug/net10.0-ios26.0/Microsoft.Maui.Maps.dll
  Controls.BindingSourceGen -> /Users/cloudtest/vss/_work/1/s/artifacts/bin/Controls.BindingSourceGen/Debug/netstandard2.0/Microsoft.Maui.Controls.BindingSourceGen.dll
  ##vso[build.updatebuildnumber]10.0.60-ci+azdo.13763453
  Controls.Core -> /Users/cloudtest/vss/_work/1/s/artifacts/bin/Controls.Core/Debug/net10.0-ios26.0/Microsoft.Maui.Controls.dll
  ##vso[build.updatebuildnumber]10.0.60-ci+azdo.13763453
  ##vso[build.updatebuildnumber]10.0.60-ci+azdo.13763453
  ##vso[build.updatebuildnumber]10.0.60-ci+azdo.13763453
  Controls.Xaml -> /Users/cloudtest/vss/_work/1/s/artifacts/bin/Controls.Xaml/Debug/net10.0-ios26.0/Microsoft.Maui.Controls.Xaml.dll
  Controls.Maps -> /Users/cloudtest/vss/_work/1/s/artifacts/bin/Controls.Maps/Debug/net10.0-ios26.0/Microsoft.Maui.Controls.Maps.dll
  Controls.Foldable -> /Users/cloudtest/vss/_work/1/s/artifacts/bin/Controls.Foldable/Debug/net10.0-ios26.0/Microsoft.Maui.Controls.Foldable.dll
  ##vso[build.updatebuildnumber]10.0.60-ci+azdo.13763453
  Microsoft.AspNetCore.Components.WebView.Maui -> /Users/cloudtest/vss/_work/1/s/artifacts/bin/Microsoft.AspNetCore.Components.WebView.Maui/Debug/net10.0-ios26.0/Microsoft.AspNetCore.Components.WebView.Maui.dll
  Detected signing identity:
    Code Signing Key: "" (-)
    Provisioning Profile: "" () - no entitlements
    Bundle Id: com.microsoft.maui.uitests
    App Id: com.microsoft.maui.uitests
  Controls.TestCases.HostApp -> /Users/cloudtest/vss/_work/1/s/artifacts/bin/Controls.TestCases.HostApp/Debug/net10.0-ios/iossimulator-arm64/Controls.TestCases.HostApp.dll
  Optimizing assemblies for size may change the behavior of the app. Be sure to test after publishing. See: https://aka.ms/dotnet-illink
  Optimizing assemblies for size. This process might take a while.

Build succeeded.

/Users/cloudtest/vss/_work/1/s/.dotnet/packs/Microsoft.iOS.Sdk.net10.0_26.0/26.0.11017/targets/Xamarin.Shared.Sdk.targets(309,3): warning : RuntimeIdentifier was set on the command line, and will override the value for RuntimeIdentifiers set in the project file. [/Users/cloudtest/vss/_work/1/s/src/Controls/tests/TestCases.HostApp/Controls.TestCases.HostApp.csproj::TargetFramework=net10.0-ios]
    1 Warning(s)
    0 Error(s)

Time Elapsed 00:00:42.09
  Determining projects to restore...
  Restored /Users/cloudtest/vss/_work/1/s/src/Controls/src/BindingSourceGen/Controls.BindingSourceGen.csproj (in 351 ms).
  Restored /Users/cloudtest/vss/_work/1/s/src/Graphics/src/Graphics/Graphics.csproj (in 364 ms).
  Restored /Users/cloudtest/vss/_work/1/s/src/Essentials/src/Essentials.csproj (in 370 ms).
  Restored /Users/cloudtest/vss/_work/1/s/src/Controls/src/Core/Controls.Core.csproj (in 386 ms).
  Restored /Users/cloudtest/vss/_work/1/s/src/Core/src/Core.csproj (in 364 ms).
  8 of 13 projects are up-to-date for restore.
  Controls.CustomAttributes -> /Users/cloudtest/vss/_work/1/s/artifacts/bin/Controls.CustomAttributes/Debug/net10.0/Controls.CustomAttributes.dll
  ##vso[build.updatebuildnumber]10.0.60-ci+azdo.13763453
  Graphics -> /Users/cloudtest/vss/_work/1/s/artifacts/bin/Graphics/Debug/net10.0/Microsoft.Maui.Graphics.dll
  ##vso[build.updatebuildnumber]10.0.60-ci+azdo.13763453
  Essentials -> /Users/cloudtest/vss/_work/1/s/artifacts/bin/Essentials/Debug/net10.0/Microsoft.Maui.Essentials.dll
  ##vso[build.updatebuildnumber]10.0.60-ci+azdo.13763453
  Core -> /Users/cloudtest/vss/_work/1/s/artifacts/bin/Core/Debug/net10.0/Microsoft.Maui.dll
  Controls.BindingSourceGen -> /Users/cloudtest/vss/_work/1/s/artifacts/bin/Controls.BindingSourceGen/Debug/netstandard2.0/Microsoft.Maui.Controls.BindingSourceGen.dll
  ##vso[build.updatebuildnumber]10.0.60-ci+azdo.13763453
  Controls.Core -> /Users/cloudtest/vss/_work/1/s/artifacts/bin/Controls.Core/Debug/net10.0/Microsoft.Maui.Controls.dll
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VSTest version 18.0.1 (arm64)

Starting test execution, please wait...
A total of 1 test files matched the specified pattern.
/Users/cloudtest/vss/_work/1/s/artifacts/bin/Controls.TestCases.iOS.Tests/Debug/net10.0/Controls.TestCases.iOS.Tests.dll
[xUnit.net 00:00:00.00] xUnit.net VSTest Adapter v2.8.2+699d445a1a (64-bit .NET 10.0.0)
[xUnit.net 00:00:00.04]   Discovering: Controls.TestCases.iOS.Tests
[xUnit.net 00:00:00.12]   Discovered:  Controls.TestCases.iOS.Tests
NUnit Adapter 4.5.0.0: Test execution started
Running selected tests in /Users/cloudtest/vss/_work/1/s/artifacts/bin/Controls.TestCases.iOS.Tests/Debug/net10.0/Controls.TestCases.iOS.Tests.dll
   NUnit3TestExecutor discovered 1 of 1 NUnit test cases using Current Discovery mode, Non-Explicit run
>>>>> 4/7/2026 3:10:26 AM FixtureSetup for Issue17283(iOS)
>>>>> 4/7/2026 3:10:30 AM CarouselViewShouldScrollToRightPosition Start
>>>>> 4/7/2026 3:10:33 AM CarouselViewShouldScrollToRightPosition Stop
  Passed CarouselViewShouldScrollToRightPosition [2 s]
NUnit Adapter 4.5.0.0: Test execution complete

Test Run Successful.
Total tests: 1
     Passed: 1
 Total time: 19.3875 Seconds

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/Users/cloudtest/vss/_work/1/s/.dotnet/packs/Microsoft.iOS.Sdk.net10.0_26.0/26.0.11017/targets/Xamarin.Shared.Sdk.targets(309,3): warning : RuntimeIdentifier was set on the command line, and will override the value for RuntimeIdentifiers set in the project file. [/Users/cloudtest/vss/_work/1/s/src/Controls/tests/TestCases.HostApp/Controls.TestCases.HostApp.csproj::TargetFramework=net10.0-ios]
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Build succeeded.

/Users/cloudtest/vss/_work/1/s/.dotnet/packs/Microsoft.iOS.Sdk.net10.0_26.0/26.0.11017/targets/Xamarin.Shared.Sdk.targets(309,3): warning : RuntimeIdentifier was set on the command line, and will override the value for RuntimeIdentifiers set in the project file. [/Users/cloudtest/vss/_work/1/s/src/Controls/tests/TestCases.HostApp/Controls.TestCases.HostApp.csproj::TargetFramework=net10.0-ios]
    1 Warning(s)
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VSTest version 18.0.1 (arm64)

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A total of 1 test files matched the specified pattern.
/Users/cloudtest/vss/_work/1/s/artifacts/bin/Controls.TestCases.iOS.Tests/Debug/net10.0/Controls.TestCases.iOS.Tests.dll
[xUnit.net 00:00:00.00] xUnit.net VSTest Adapter v2.8.2+699d445a1a (64-bit .NET 10.0.0)
[xUnit.net 00:00:00.03]   Discovering: Controls.TestCases.iOS.Tests
[xUnit.net 00:00:00.12]   Discovered:  Controls.TestCases.iOS.Tests
NUnit Adapter 4.5.0.0: Test execution started
Running selected tests in /Users/cloudtest/vss/_work/1/s/artifacts/bin/Controls.TestCases.iOS.Tests/Debug/net10.0/Controls.TestCases.iOS.Tests.dll
   NUnit3TestExecutor discovered 1 of 1 NUnit test cases using Current Discovery mode, Non-Explicit run
>>>>> 4/7/2026 3:13:10 AM FixtureSetup for Issue17283(iOS)
>>>>> 4/7/2026 3:13:14 AM CarouselViewShouldScrollToRightPosition Start
>>>>> 4/7/2026 3:13:16 AM CarouselViewShouldScrollToRightPosition Stop
  Passed CarouselViewShouldScrollToRightPosition [2 s]
NUnit Adapter 4.5.0.0: Test execution complete

Test Run Successful.
Total tests: 1
     Passed: 1
 Total time: 18.2556 Seconds

🤖 AI Summary

📊 Expand Full Review — 9fac735 · enable ios26 test.

I validated the alternative fix suggested in the AI summary, but it did not resolve the reported issues, so no changes were made to the PR. I also verified tests 17283 and 16020 locally on iOS26—both pass with the fix and fail without it.

Without Fix	With Fix

🤖 AI Summary

🤖 AI Summary

📊 Expand Full Review — 9fac735 · enable ios26 test.

I validated the alternative fix suggested in the AI summary, but it did not resolve the reported issue. However, the summary also highlighted two additional concerns, which have been addressed. No other major concerns in the AI summary.

• _scrollDebounce was canceled but not disposed before being overwritten, causing a CancellationTokenSource leak during rapid position changes. This is fixed by capturing the old reference, assigning the new one, then canceling and disposing the old instance.

• catch (Exception) was swallowing all exceptions, including real issues. This is fixed by narrowing it to catch (OperationCanceledException), which is the only expected exception in this scenario.

Both tests pass without a fix - could you please verify?

@kubaflo This issue reproduces only on iOS 26 and does not occur on iOS 18. I verified this locally using the latest main branch—the test fails without the fix and passes with the fix on iOS 26, while it passes even without the fix on iOS 18.

iOS 26 Test Results:

Without Fix	With Fix

Code Review — PR #34013

Independent Assessment

What this changes: Adds an iOS 26-specific debounce in CarouselViewController2.UpdateFromPosition() using CancellationTokenSource + Task.Delay(100) + MainThread.BeginInvokeOnMainThread. On iOS <26, behavior is unchanged. Removes iOS 26 skip guards from two existing tests and updates a snapshot.

Inferred motivation: iOS 26 changed UICollectionView.ScrollToItem() to fire intermediate scroll position callbacks during animation. These callbacks re-trigger UpdateFromPosition() with stale positions, interrupting the target scroll.

Reconciliation with PR Narrative

Agreement: ✅ Code matches description. The debounce pattern is appropriate — iOS 26 fires intermediate callbacks that iOS 18 didn't, and the 100ms delay lets the scroll animation settle before processing the final position. Author tested on all 4 platforms.

Findings

✅ Good — CancellationTokenSource debounce is correct

• old?.Cancel(); old?.Dispose() before creating new CTS — proper lifecycle
• Token passed to both Task.Delay and ContinueWith — cancellation works at both stages
• OperationCanceledException caught — expected when superseded by newer call
• State re-validation inside MainThread.BeginInvokeOnMainThread callback (checking InitialPositionSet, ItemsView, ItemsSource) — avoids stale/disposed state after delay ✅
• Follows the exact same pattern as existing UpdateInitialPosition() method

✅ Good — Cleanup in Dispose

• _scrollDebounce?.Cancel(); _scrollDebounce?.Dispose(); _scrollDebounce = null; in Dispose(bool) — prevents dangling delayed callbacks after disposal
• PublicAPI.Unshipped.txt updated for both net-ios and net-maccatalyst — correct since this file compiles for both platforms

✅ Good — Test changes

• Removed iOS 26 skip guards from Issue16020 and Issue17283 — these tests should now pass on iOS 26 since the underlying fix addresses the regression
• Updated iOS 26 snapshot for CarouselViewShouldScrollToRightPosition

⚠️ Issue — Stale comment about delay value

The comment says:

"A slightly longer delay than UpdateInitialPosition's 100ms was empirically chosen"

But the actual delay is Task.Delay(100, token) — the same 100ms, not longer. This comment was accurate when the delay was 200ms (earlier revision) but is now stale after the value was reduced.

Suggestion: Update comment to:

// On iOS 26, UICollectionView can emit intermediate scroll callbacks before settling.
// A 100ms delay (matching UpdateInitialPosition) was empirically chosen to ensure
// the scroll operation runs after those intermediate callbacks complete.

💡 Suggestion — Match codebase pattern for iOS 26 version check

The PR uses OperatingSystem.IsIOSVersionAtLeast(26) alone. While this technically works on MacCatalyst (returns true for MacCatalyst 26+), the established codebase pattern for iOS 26 checks consistently uses the dual form:

if (OperatingSystem.IsIOSVersionAtLeast(26) || OperatingSystem.IsMacCatalystVersionAtLeast(26))

Examples: NavigationRenderer.cs:958, ShellPageRendererTracker.cs:296,347,471,581,779, ShellSectionRenderer.cs:836, ShellItemRenderer.cs:133, ShellItemTransition.cs:23 — all use the dual pattern.

For consistency and future-proofing, consider matching this pattern. It's a no-op change functionally but keeps the codebase convention uniform.

ℹ️ Note — async void is an existing pattern

UpdateFromPosition() changed from void to async void. While async void is generally risky (unhandled exceptions crash the process), this class already uses async void in ViewDidLayoutSubviews() and AttachingToWindow(). The OperationCanceledException is caught, and the MainThread.BeginInvokeOnMainThread callback follows the same fire-and-forget pattern as UpdateInitialPosition. This is consistent.

ℹ️ Note — CI Status

Failing checks: Helix Unit Tests (Windows Debug) and Integration Tests (Build macOS). These appear to be infrastructure-related flaky failures, not related to the CarouselView iOS changes.

Devil's Advocate

• "Is 100ms enough?" — The existing UpdateInitialPosition uses the same value and works. The debounce CancellationToken ensures that rapid re-calls are properly superseded, so even if 100ms isn't quite long enough in some edge case, the final call wins.
• "Could this introduce scroll lag?" — The 100ms delay only applies to iOS 26+ UpdateFromPosition (programmatic position changes), not to user-initiated scrolling. The lag is imperceptible to users.
• "What about MacCatalyst?" — The file compiles for both iOS and MacCatalyst. IsIOSVersionAtLeast(26) returns true on MacCatalyst 26+. The debounce activates on both platforms, which is correct since MacCatalyst shares the same UICollectionView behavior.

Verdict: LGTM with minor nits

Confidence: high
Summary: Correct fix for a real iOS 26 regression. The CancellationTokenSource debounce pattern is well-implemented, follows existing codebase patterns, and properly cleans up in Dispose. Two minor suggestions: (1) fix the stale delay comment, (2) consider matching the dual version check pattern. Neither blocks merge.

Review performed by Copilot CLI using the code-review skill