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[flutter_tools] Report preview reload timing analytics in LspPreviewDetector - #192120
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…etector In Flutter 3.44, `LspPreviewDetector` became the default preview detector (flutter#184473), but did not instrument `previewAnalytics.startPreviewReloadStopwatch()` or `previewAnalytics.reportPreviewReloadTiming()`. This caused a severe drop in reported `preview-reload-time` telemetry events. This change instruments `LspPreviewDetector` to start the reload stopwatch on file changes, report reload timings after change detection completes, and reset the stopwatch on errors. Non-Dart file edits are also filtered out to prevent unnecessary reload events.
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This pull request introduces preview reload timing telemetry to the LspPreviewDetector and adds a comprehensive test suite to verify its behavior. Feedback on the changes suggests addressing a potential issue where programmatic errors are silently swallowed in the catch block of the detector, and refactoring a test assertion to avoid fragility when verifying sent telemetry events.
…lytics_data # Conflicts: # packages/flutter_tools/lib/src/widget_preview/lsp_preview_detector.dart
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flutter/flutter@0cbd1a4...70797e1 2026-09-02 [email protected] [analysis] Upgrade package:analyzer to 14.3.0 and enable custom plugin compilation (flutter/flutter#191590) 2026-09-02 [email protected] Roll Dart SDK from d8d7869d8031 to 9a8fbde80f6c (1 revision) (flutter/flutter#192179) 2026-09-02 [email protected] Roll Skia from dec311244db4 to ae22da2e8308 (1 revision) (flutter/flutter#192177) 2026-09-02 [email protected] [tool] Migrate DoctorCommand to modular dependency injection (flutter/flutter#190758) 2026-09-02 [email protected] Roll Skia from 482b7e285244 to dec311244db4 (3 revisions) (flutter/flutter#192161) 2026-09-02 [email protected] Roll Skia from 28447e9fb8d5 to 482b7e285244 (3 revisions) (flutter/flutter#192157) 2026-09-02 [email protected] feat: Add placeholder to DecorationImage (flutter/flutter#191528) 2026-09-02 [email protected] [Android] Do not schedule engine frames on a detached FlutterJNI (flutter/flutter#191204) 2026-09-02 [email protected] Roll Skia from 3a242fb7cdb3 to 28447e9fb8d5 (1 revision) (flutter/flutter#192145) 2026-09-02 [email protected] Roll Dart SDK from 9164def35347 to d8d7869d8031 (2 revisions) (flutter/flutter#192144) 2026-09-02 [email protected] Add FadeInImageTransition.fadeInOver to fade the image in over the placeholder (flutter/flutter#186246) 2026-09-02 [email protected] Roll Skia from 63d13ec4df6d to 3a242fb7cdb3 (9 revisions) (flutter/flutter#192138) 2026-09-02 [email protected] [flutter_tools] Add --no-plugins flag and disable plugins for benchmark (flutter/flutter#192129) 2026-09-02 [email protected] [tool] Migrate ChannelCommand to modular dependency injection (flutter/flutter#190751) 2026-09-01 [email protected] Add mouseCursor to RawScrollbar (flutter/flutter#185750) 2026-09-01 [email protected] Fix self-comparison and assert typos in TestSemantics (flutter/flutter#191938) 2026-09-01 [email protected] [Linux] Wait for frames to be rendered before using them in another context (flutter/flutter#192094) 2026-09-01 [email protected] [wimp] Turn on multithreading for wimp. (flutter/flutter#191747) 2026-09-01 [email protected] Roll Skia from 3911a1fe7f7a to 63d13ec4df6d (6 revisions) (flutter/flutter#192125) 2026-09-01 [email protected] Remove the redundant flutter/shell/platform/android:robolectric_tests build target (flutter/flutter#192117) 2026-09-01 [email protected] [iOS] Preserve semantics parents after reparenting (flutter/flutter#189686) 2026-09-01 [email protected] [flutter_tools] Report preview reload timing analytics in LspPreviewDetector (flutter/flutter#192120) 2026-09-01 [email protected] [flutter_tools] Implement Templates slice and flutter create integration (flutter/flutter#191748) 2026-09-01 [email protected] Uiscene migrate add2app hosts (flutter/flutter#191847) 2026-09-01 [email protected] Roll Packages from d642322 to 7a7912f (8 revisions) (flutter/flutter#192119) 2026-09-01 [email protected] [web] Anchor flt-semantics-host at 0,0 to fix WebKit semantics offset (flutter/flutter#190486) 2026-09-01 [email protected] Replace Shell::WaitForFirstFrame with an asynchronous API that matches the Shell threading model (flutter/flutter#191841) 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 [email protected] 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
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…r#12727) flutter/flutter@0cbd1a4...70797e1 2026-09-02 [email protected] [analysis] Upgrade package:analyzer to 14.3.0 and enable custom plugin compilation (flutter/flutter#191590) 2026-09-02 [email protected] Roll Dart SDK from d8d7869d8031 to 9a8fbde80f6c (1 revision) (flutter/flutter#192179) 2026-09-02 [email protected] Roll Skia from dec311244db4 to ae22da2e8308 (1 revision) (flutter/flutter#192177) 2026-09-02 [email protected] [tool] Migrate DoctorCommand to modular dependency injection (flutter/flutter#190758) 2026-09-02 [email protected] Roll Skia from 482b7e285244 to dec311244db4 (3 revisions) (flutter/flutter#192161) 2026-09-02 [email protected] Roll Skia from 28447e9fb8d5 to 482b7e285244 (3 revisions) (flutter/flutter#192157) 2026-09-02 [email protected] feat: Add placeholder to DecorationImage (flutter/flutter#191528) 2026-09-02 [email protected] [Android] Do not schedule engine frames on a detached FlutterJNI (flutter/flutter#191204) 2026-09-02 [email protected] Roll Skia from 3a242fb7cdb3 to 28447e9fb8d5 (1 revision) (flutter/flutter#192145) 2026-09-02 [email protected] Roll Dart SDK from 9164def35347 to d8d7869d8031 (2 revisions) (flutter/flutter#192144) 2026-09-02 [email protected] Add FadeInImageTransition.fadeInOver to fade the image in over the placeholder (flutter/flutter#186246) 2026-09-02 [email protected] Roll Skia from 63d13ec4df6d to 3a242fb7cdb3 (9 revisions) (flutter/flutter#192138) 2026-09-02 [email protected] [flutter_tools] Add --no-plugins flag and disable plugins for benchmark (flutter/flutter#192129) 2026-09-02 [email protected] [tool] Migrate ChannelCommand to modular dependency injection (flutter/flutter#190751) 2026-09-01 [email protected] Add mouseCursor to RawScrollbar (flutter/flutter#185750) 2026-09-01 [email protected] Fix self-comparison and assert typos in TestSemantics (flutter/flutter#191938) 2026-09-01 [email protected] [Linux] Wait for frames to be rendered before using them in another context (flutter/flutter#192094) 2026-09-01 [email protected] [wimp] Turn on multithreading for wimp. (flutter/flutter#191747) 2026-09-01 [email protected] Roll Skia from 3911a1fe7f7a to 63d13ec4df6d (6 revisions) (flutter/flutter#192125) 2026-09-01 [email protected] Remove the redundant flutter/shell/platform/android:robolectric_tests build target (flutter/flutter#192117) 2026-09-01 [email protected] [iOS] Preserve semantics parents after reparenting (flutter/flutter#189686) 2026-09-01 [email protected] [flutter_tools] Report preview reload timing analytics in LspPreviewDetector (flutter/flutter#192120) 2026-09-01 [email protected] [flutter_tools] Implement Templates slice and flutter create integration (flutter/flutter#191748) 2026-09-01 [email protected] Uiscene migrate add2app hosts (flutter/flutter#191847) 2026-09-01 [email protected] Roll Packages from d642322 to 7a7912f (8 revisions) (flutter/flutter#192119) 2026-09-01 [email protected] [web] Anchor flt-semantics-host at 0,0 to fix WebKit semantics offset (flutter/flutter#190486) 2026-09-01 [email protected] Replace Shell::WaitForFirstFrame with an asynchronous API that matches the Shell threading model (flutter/flutter#191841) 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 [email protected] 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
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…pPreviewDetector (#192256) 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: #192120 ### Impact Description: In Flutter 3.44 ([#184473](#184473)), `LspPreviewDetector` became the default preview detector, but did not instrument preview reload timing analytics (`previewAnalytics.startPreviewReloadStopwatch()` and `previewAnalytics.reportPreviewReloadTiming()`). This caused a severe drop in reported `preview-reload-time` telemetry events for the widget previewer. This cherry-pick restores reporting of reload timing metrics and filters out non-Dart file edits to avoid spurious reload timing events. ### Changelog Description: [flutter/192120] Fixes missing preview reload timing analytics in LspPreviewDetector across all platforms. ### Workaround: None. Telemetry for widget preview reload timing is omitted unless instrumented. ### 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: Run `packages/flutter_tools` unit tests: `dart test test/commands.shard/hermetic/widget_preview/lsp_preview_detector_test.dart`
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…r#12727) flutter/flutter@0cbd1a4...70797e1 2026-09-02 [email protected] [analysis] Upgrade package:analyzer to 14.3.0 and enable custom plugin compilation (flutter/flutter#191590) 2026-09-02 [email protected] Roll Dart SDK from d8d7869d8031 to 9a8fbde80f6c (1 revision) (flutter/flutter#192179) 2026-09-02 [email protected] Roll Skia from dec311244db4 to ae22da2e8308 (1 revision) (flutter/flutter#192177) 2026-09-02 [email protected] [tool] Migrate DoctorCommand to modular dependency injection (flutter/flutter#190758) 2026-09-02 [email protected] Roll Skia from 482b7e285244 to dec311244db4 (3 revisions) (flutter/flutter#192161) 2026-09-02 [email protected] Roll Skia from 28447e9fb8d5 to 482b7e285244 (3 revisions) (flutter/flutter#192157) 2026-09-02 [email protected] feat: Add placeholder to DecorationImage (flutter/flutter#191528) 2026-09-02 [email protected] [Android] Do not schedule engine frames on a detached FlutterJNI (flutter/flutter#191204) 2026-09-02 [email protected] Roll Skia from 3a242fb7cdb3 to 28447e9fb8d5 (1 revision) (flutter/flutter#192145) 2026-09-02 [email protected] Roll Dart SDK from 9164def35347 to d8d7869d8031 (2 revisions) (flutter/flutter#192144) 2026-09-02 [email protected] Add FadeInImageTransition.fadeInOver to fade the image in over the placeholder (flutter/flutter#186246) 2026-09-02 [email protected] Roll Skia from 63d13ec4df6d to 3a242fb7cdb3 (9 revisions) (flutter/flutter#192138) 2026-09-02 [email protected] [flutter_tools] Add --no-plugins flag and disable plugins for benchmark (flutter/flutter#192129) 2026-09-02 [email protected] [tool] Migrate ChannelCommand to modular dependency injection (flutter/flutter#190751) 2026-09-01 [email protected] Add mouseCursor to RawScrollbar (flutter/flutter#185750) 2026-09-01 [email protected] Fix self-comparison and assert typos in TestSemantics (flutter/flutter#191938) 2026-09-01 [email protected] [Linux] Wait for frames to be rendered before using them in another context (flutter/flutter#192094) 2026-09-01 [email protected] [wimp] Turn on multithreading for wimp. (flutter/flutter#191747) 2026-09-01 [email protected] Roll Skia from 3911a1fe7f7a to 63d13ec4df6d (6 revisions) (flutter/flutter#192125) 2026-09-01 [email protected] Remove the redundant flutter/shell/platform/android:robolectric_tests build target (flutter/flutter#192117) 2026-09-01 [email protected] [iOS] Preserve semantics parents after reparenting (flutter/flutter#189686) 2026-09-01 [email protected] [flutter_tools] Report preview reload timing analytics in LspPreviewDetector (flutter/flutter#192120) 2026-09-01 [email protected] [flutter_tools] Implement Templates slice and flutter create integration (flutter/flutter#191748) 2026-09-01 [email protected] Uiscene migrate add2app hosts (flutter/flutter#191847) 2026-09-01 [email protected] Roll Packages from d642322 to 7a7912f (8 revisions) (flutter/flutter#192119) 2026-09-01 [email protected] [web] Anchor flt-semantics-host at 0,0 to fix WebKit semantics offset (flutter/flutter#190486) 2026-09-01 [email protected] Replace Shell::WaitForFirstFrame with an asynchronous API that matches the Shell threading model (flutter/flutter#191841) 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 [email protected] 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
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In Flutter 3.44 (#184473),
LspPreviewDetectorbecame the default preview detector, but did not instrumentpreviewAnalytics.startPreviewReloadStopwatch()orpreviewAnalytics.reportPreviewReloadTiming(). This caused a severe drop in reportedpreview-reload-timetelemetry events.This change instruments
LspPreviewDetectorto start the reload stopwatch on file changes, report reload timings after change detection completes, and reset the stopwatch on errors. Non-Dart file edits are also filtered out to avoid unnecessary reload events.Pre-launch Checklist
///).