[Android] Shell: Fix fragment teardown crash

[PureWeen]

Note

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Description

Preview 7 Android Mono Controls device tests repeatedly crashed on separate machines after Shell tests with:

System.NotSupportedException: Unable to activate instance of type Microsoft.Maui.Controls.Handlers.ShellItemWrapperFragment from native handle

The stack ran through TypeManager.CreateInstance -> AndroidValueManager.CreatePeer -> Fragment.n_OnDestroyView. A preceding CoreCLR run stack-overflowed repeatedly in the same Fragment.n_OnDestroyView native callback.

Root cause: ShellItemHandlerAdapter.Dispose() and ShellSectionHandlerAdapter.Dispose() called _wrapperFragment?.Dispose() on the managed callable wrapper before AndroidX FragmentManager had finished native fragment teardown. FragmentManager still owned the fragment and later invoked OnDestroyView/OnDestroy; the managed peer had already been disposed, so the native-to-managed callback failed.

Fix: Remove the premature _wrapperFragment?.Dispose() call in both adapters. Destroyed?.Invoke, DisconnectHandler(), and clearing _wrapperFragment are preserved, so handler cleanup and event semantics are unchanged. AndroidX completes the fragment lifecycle and releases its native references, after which the managed wrapper can be collected normally.

Changes

• ShellItemHandlerAdapter.Dispose() no longer disposes its FragmentManager-owned wrapper fragment.
• ShellSectionHandlerAdapter.Dispose() applies the same ownership correction.
• Both sites document why native lifecycle completion must precede managed peer release.

Validation

• maui-pr build 1537782 completed successfully.
• maui-pr-devicetests build 1537785 completed. The overall pipeline is red only for unrelated, baseline/platform-mismatched test failures listed below.
• Android CoreCLR Controls: Helix job 285167e7-e91d-48bf-affa-af69928f75e4 completed the full Controls suite. Its log contains no Stack overflow, Fragment.n_OnDestroyView crash, wrapper activation exception, or DEVICE_NOT_FOUND.
• Android Mono Controls: Helix job 83a0120e-b322-4681-8d71-152b5fe03b4a likewise completed the full Controls suite with none of the prior crash signatures.
• Both Android runtimes reported the same two unrelated Entry failures (setSpan (5001 ... 5001) ends beyond length 5000). The identical Entry failures already occur on the exact-base build 1537360, including its Mono Controls work item.
• Both Android Core work items reported the two existing StatusBarThemeAppliesWhenHandlerConnects failures (MauiContext did not have a valid window), identical to exact-base build 1537360 on both runtimes.
• The iOS Helix failures are unrelated to this Android-only diff: the existing StatusBarThemeFlowsThroughRootController failure is also present on exact-base build 1537360; one CoreCLR iOS 26 WebView URL-encoding test also failed.
• The separately-triggered maui-pr-uitests build 1537784 remains in progress. Its completed WinUI failures are unrelated: DragEvents and the Label visual-baseline failures reproduce on exact-base UI build 1537359; HorizontalGridFooterExpandsToContentWidth runs on Windows, where these .Android.cs changes are not compiled.
• A MAUI-specific lifecycle review found no high-confidence ownership, teardown-ordering, or leak issue. Retention lasts only until FragmentManager finishes teardown.
• Focused local Android execution was blocked because this machine does not have the repository-required 11.0.100-preview.7.26379.122 SDK or XHarness installed. No local test result is claimed.

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[Copilot]

Pull request overview

This PR addresses an Android Shell crash during fragment teardown by avoiding premature disposal of managed fragment wrappers that are still owned by AndroidX FragmentManager, preventing native-to-managed callbacks (e.g., OnDestroyView/OnDestroy) from running after the managed peer has been disposed.

Changes:

• Stop explicitly disposing _wrapperFragment in ShellItemHandlerAdapter.Dispose(), relying on FragmentManager to dispose the fragment at the correct lifecycle point.
• Stop explicitly disposing _wrapperFragment in ShellSectionHandlerAdapter.Dispose() for the same reason.
• Add clarifying comments documenting the lifecycle/ownership rationale.

Show a summary per file

File	Description
src/Controls/src/Core/Handlers/Shell/ShellItemHandler.Android.cs	Removes _wrapperFragment?.Dispose() from ShellItemHandlerAdapter.Dispose() and documents why fragment disposal must be left to FragmentManager.
src/Controls/src/Core/Handlers/Shell/ShellSectionHandler.Android.cs	Removes _wrapperFragment?.Dispose() from ShellSectionHandlerAdapter.Dispose() and documents why fragment disposal must be left to FragmentManager.

Copilot's findings

• Files reviewed: 2/2 changed files
• Comments generated: 0

[kubaflo]

@PureWeen I checked the targeted Android Helix results. The original ShellItemWrapperFragment.OnDestroyView / JNI activation crash is gone in both CoreCLR and Mono runs, so this PR fixed the failure it targeted. The remaining Android failures are unrelated: the two long-Entry setSpan tests in Controls and two status-bar tests in Core.

[kubaflo]

@PureWeen The intended Shell teardown crash is confirmed fixed at f8b46236 in both Android Mono and CoreCLR Helix runs. The remaining failures are separate regressions covered by #37051 and #37052. Please merge #37048 when the required checks/review allow it.