Since `flutter clean` can delete the `.dart_tool/` directory while a
`flutter widget-preview start` command is active, it's possible for the
`widget_preview_scaffold` to be deleted and cause the preview process to
crash.

This change works around this issue by always generating the
`widget_preview_scaffold` project under $TMP on each invocation of the
previewer. This doesn't result in much of a regression in startup times
as we currently aren't launching the previewer using restored state as
this isn't currently possible with the web device targets. Moving the
scaffold under $TMP means Flutter tooling will never accidentally delete
the scaffold while the previewer is running.

Filed #179036 to track
reverting this behavior when a better solution is found.

Fixes #175058

Since `flutter clean` can delete the `.dart_tool/` directory while a
`flutter widget-preview start` command is active, it's possible for the
`widget_preview_scaffold` to be deleted and cause the preview process to
crash.

This change works around this issue by always generating the
`widget_preview_scaffold` project under $TMP on each invocation of the
previewer. This doesn't result in much of a regression in startup times
as we currently aren't launching the previewer using restored state as
this isn't currently possible with the web device targets. Moving the
scaffold under $TMP means Flutter tooling will never accidentally delete
the scaffold while the previewer is running.

Filed #179036 to track
reverting this behavior when a better solution is found.

Fixes #175058

…tter/flutter#179039)

…tter/flutter#179039)

…tter/flutter#179039)

…tter/flutter#179039)

…tter/flutter#179039)

…tter/flutter#179039)

…tter/flutter#179039)

…tter/flutter#179039)

flutter/flutter@3f553f6...7b98d50

2025-11-26 98614782+auto-submit[bot]@users.noreply.github.com Reverts "Fix for win32 embedder failing to send all alt key downs to the flutter app (#179097)" (flutter/flutter#179136)
2025-11-26 matt.kosarek@canonical.com Fix for win32 embedder failing to send all alt key downs to the flutter app (flutter/flutter#179097)
2025-11-26 katelovett@google.com Modernize framework lints (flutter/flutter#179089)
2025-11-25 98614782+auto-submit[bot]@users.noreply.github.com Reverts "Add framework-side hitTestBehavior support to Semantics (#178817)" (flutter/flutter#179100)
2025-11-25 zhongliu88889@gmail.com Add framework-side hitTestBehavior support to Semantics (flutter/flutter#178817)
2025-11-25 engine-flutter-autoroll@skia.org Roll Packages from e019cf9 to cc3dca6 (1 revision) (flutter/flutter#179081)
2025-11-25 matt.kosarek@canonical.com Add tooltip windows to the windowing API alongside the window positioning logic (flutter/flutter#177404)
2025-11-25 matt.kosarek@canonical.com FlutterWindowsView::SendWindowMetrics now reliably sends the display_id (flutter/flutter#179053)
2025-11-25 31859944+LongCatIsLooong@users.noreply.github.com Remove semantics geometry shortcircuit (flutter/flutter#178680)
2025-11-25 bruno.leroux@gmail.com Add an assert message when OverlayEntry.remove is called twice (flutter/flutter#178163)
2025-11-25 engine-flutter-autoroll@skia.org Roll Fuchsia Linux SDK from pOO9Jl9HTLsEmks6y... to nzuAxCJGeJbkZCTkr... (flutter/flutter#179066)
2025-11-25 okorohelijah@google.com Dynamically set MinimumOSVersion in App.framework (flutter/flutter#178253)
2025-11-25 engine-flutter-autoroll@skia.org Roll Skia from d83c30b090f4 to 925c311f4b37 (2 revisions) (flutter/flutter#179060)
2025-11-25 fluttergithubbot@gmail.com Marks Linux build_android_host_app_with_module_aar to be unflaky (flutter/flutter#174864)
2025-11-25 fluttergithubbot@gmail.com Marks Linux_mokey complex_layout__start_up to be unflaky (flutter/flutter#174865)
2025-11-25 vegorov@google.com Manual Dart SDK roll to 3.11.0-169.0.dev (flutter/flutter#179054)
2025-11-25 katelovett@google.com Bump Dart to 3.9 (flutter/flutter#179041)
2025-11-25 engine-flutter-autoroll@skia.org Roll Skia from e298c2f93ebf to d83c30b090f4 (2 revisions) (flutter/flutter#179058)
2025-11-24 30870216+gaaclarke@users.noreply.github.com updated licenses_cpp readme (flutter/flutter#178874)
2025-11-24 engine-flutter-autoroll@skia.org Roll Skia from 43d2020be565 to e298c2f93ebf (5 revisions) (flutter/flutter#179046)
2025-11-24 116356835+AbdeMohlbi@users.noreply.github.com Refactor `_isLabel` method in `stepper.dart` to use `any` for better readablity (flutter/flutter#178909)
2025-11-24 49699333+dependabot[bot]@users.noreply.github.com Bump actions/checkout from 5 to 6 in the all-github-actions group (flutter/flutter#179049)
2025-11-24 38378650+hgraceb@users.noreply.github.com Disposes test restoration manager when accessed by bindings (flutter/flutter#176519)
2025-11-24 bkonyi@google.com [ Widget Preview ] Always generate scaffold under `$TMP` (flutter/flutter#179039)
2025-11-24 engine-flutter-autoroll@skia.org Roll Packages from e67b6be to e019cf9 (9 revisions) (flutter/flutter#179035)
2025-11-24 1063596+reidbaker@users.noreply.github.com Update CHANGELOG.md for Flutter 3.38.3 (flutter/flutter#178935)
2025-11-24 116356835+AbdeMohlbi@users.noreply.github.com Remove unnecessary `String.valueOf` in `SettingsChannel.java‎` (flutter/flutter#178590)
2025-11-24 katelovett@google.com Roll pub manually, pick up flutter_lints in examples/api (flutter/flutter#179030)
2025-11-24 engine-flutter-autoroll@skia.org Roll Dart SDK from 24cc9a740bd3 to afca43095efa (1 revision) (flutter/flutter#179019)
2025-11-24 zezohassam@gmail.com Pass EXCLUDED_ARCHS from Xcode project to xcodebuild for macOS builds (flutter/flutter#176948)

If this roll has caused a breakage, revert this CL and stop the roller
using the controls here:
https://autoroll.skia.org/r/flutter-packages
Please CC bmparr@google.com,stuartmorgan@google.com on the revert to ensure that a human
is aware of the problem.

To file a bug in Packages: https://github.com/flutter/flutter/issues/new/choose

To report a problem with the AutoRoller itself, please file a bug:
https://issues.skia.org/issues/new?component=1389291&template=1850622

Documentation for the AutoRoller is here:
https://skia.googlesource.com/buildbot/+doc/main/autoroll/README.md

)

Since `flutter clean` can delete the `.dart_tool/` directory while a
`flutter widget-preview start` command is active, it's possible for the
`widget_preview_scaffold` to be deleted and cause the preview process to
crash.

This change works around this issue by always generating the
`widget_preview_scaffold` project under $TMP on each invocation of the
previewer. This doesn't result in much of a regression in startup times
as we currently aren't launching the previewer using restored state as
this isn't currently possible with the web device targets. Moving the
scaffold under $TMP means Flutter tooling will never accidentally delete
the scaffold while the previewer is running.

Filed flutter#179036 to track
reverting this behavior when a better solution is found.

Fixes flutter#175058

…179039) (#179050)

This pull request is created by [automatic cherry pick workflow](https://github.com/flutter/flutter/blob/main/docs/releases/Flutter-Cherrypick-Process.md#automatically-creates-a-cherry-pick-request)
Please fill in the form below, and a flutter domain expert will evaluate this cherry pick request.

### Issue Link:
What is the link to the issue this cherry-pick is addressing?

#175058

### Changelog Description:
Explain this cherry pick in one line that is accessible to most Flutter developers. See [best practices](https://github.com/flutter/flutter/blob/main/docs/releases/Hotfix-Documentation-Best-Practices.md) for examples

`flutter widget-preview start` can crash if `flutter clean` is run while the widget previewer is running.

### Impact Description:
What is the impact (ex. visual jank on Samsung phones, app crash, cannot ship an iOS app)? Does it impact development (ex. flutter doctor crashes when Android Studio is installed), or the shipping production app (the app crashes on launch)

The widget previewer can silently crash in IDEs if the user runs `flutter clean` on the project. There's no indication that the previewer has crashed other than the fact that the previewer no longer hot reloads when the user make changes to their previews.

### Workaround:
Is there a workaround for this issue?

Not running `flutter clean` while the widget previewer is running, or restarting the IDE after `flutter clean` is run.

### Risk:
What is the risk level of this cherry-pick?

### Test Coverage:
Are you confident that your fix is well-tested by automated tests?

### Validation Steps:
What are the steps to validate that this fix works?

1) Run `flutter widget-preview start`
2) Run `flutter clean` and verify the `flutter widget-preview start` process doesn't crash.

)

Since `flutter clean` can delete the `.dart_tool/` directory while a
`flutter widget-preview start` command is active, it's possible for the
`widget_preview_scaffold` to be deleted and cause the preview process to
crash.

This change works around this issue by always generating the
`widget_preview_scaffold` project under $TMP on each invocation of the
previewer. This doesn't result in much of a regression in startup times
as we currently aren't launching the previewer using restored state as
this isn't currently possible with the web device targets. Moving the
scaffold under $TMP means Flutter tooling will never accidentally delete
the scaffold while the previewer is running.

Filed flutter#179036 to track
reverting this behavior when a better solution is found.

Fixes flutter#175058