[ Tool ] Stop generating widget preview scaffold under $TMP#186476
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This pull request moves the widgetPreviewScaffold from a temporary directory to a local .widget_preview directory and adds a migration to update .gitignore. It also updates the WidgetPreviewScaffoldInspectorService to register the project root directory. Review feedback highlights that the string check for .widget_preview is too broad and may cause false positives. Additionally, there are suggestions to lower the logging level for the gitignore migration and to resolve inconsistencies between the migration logic and the project template regarding the exclusion of the bin/ directory from .gitignore.
Previously, the `widget_preview_scaffold` project was generated under the system temporary directory (`$TMP`) to work around issues with `flutter clean`. However, generating the scaffold in `$TMP` meant that the project was recreated on every run or could be lost, leading to unnecessary regeneration overhead and tracking issues. Move the generated `widget_preview_scaffold` project from `$TMP` to a `.widget_preview` directory located directly under the project root. To support this change, `WidgetPreviewGitignoreMigration` is introduced to automatically add `.widget_preview/` to the host project's `.gitignore`. In addition, `kProjectRootPath` is passed via DTD connection info to ensure `WidgetInspectorService` correctly adds the project root to pub root directories. Finally, file watchers (`LspPreviewDetector` and `PreviewDetector`) are updated to ignore the new `.widget_preview` directory. Fixes flutter#179036
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The template previously ignored `.widget_preview/*` but explicitly allowed `!.widget_preview/bin/*`. Since `.widget_preview` is a generated, ephemeral scaffold project for hosting widget previews, tracking any part of it in the host project repository is unnecessary and inconsistent with the migrator logic. Update `packages/flutter_tools/templates/app/.gitignore.tmpl` to ignore the entire `.widget_preview/` directory, aligning it with `WidgetPreviewGitignoreMigration`. Fixes flutter#179036
- Make `.widget_preview` check in `utils.dart` more specific by checking path segments to avoid false positives. - Lower logging level in `WidgetPreviewGitignoreMigration` from warning to trace. - Update tests to expect trace output. Fixes flutter#179036
The template `widget_preview_inspector_service.dart.tmpl` references `kProjectRootPath`, but `dtd_connection_info.dart.tmpl` was missing its definition. This caused analysis failures when the template or dummy project was analyzed. Added `const String kProjectRootPath = '';` to the template to resolve the error. Fixes flutter#179036
Updates kProjectRootPath generation in PreviewCodeGenerator to produce a raw string (r'...'), ensuring that absolute file paths (especially on Windows) are correctly represented without escape sequence errors. Also updates the initial constant definition in the scaffold template and inflated file to be a raw string. Fixes flutter#179036
…tartWidgetPreview
- Extract path separator RegExp to a static field in StringExtension to avoid recreation. - Revert the custom delay for waitForAnalysis in LspPreviewDetector to the default to see if it is still needed.
srawlins
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May 21, 2026
This was referenced May 22, 2026
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May 26, 2026
Roll Flutter from e03b91f1fe34 to f3a4b9897834 (63 revisions) flutter/flutter@e03b91f...f3a4b98 2026-05-26 47866232+chunhtai@users.noreply.github.com Update batch release doc to reflect latest workflow (flutter/flutter#186979) 2026-05-26 engine-flutter-autoroll@skia.org Roll Skia from 0442274cc696 to 27a819894f7c (5 revisions) (flutter/flutter#187094) 2026-05-26 bkonyi@google.com [Tool Robustness] Gracefully handle asynchronous subprocess crashes and connection timeouts (flutter/flutter#186964) 2026-05-26 bkonyi@google.com [pubspec] Bump Dart SDK constraint to ^3.13.0 (flutter/flutter#186957) 2026-05-26 engine-flutter-autoroll@skia.org Roll Dart SDK from 7eb54169841d to 00e625453c43 (1 revision) (flutter/flutter#187086) 2026-05-26 bdero@google.com [Impeller] Retire Y-coord-scale plumbing by flipping GLES at the vertex stage (flutter/flutter#186556) 2026-05-26 engine-flutter-autoroll@skia.org Roll Skia from f4f294bdf98d to 0442274cc696 (2 revisions) (flutter/flutter#187079) 2026-05-26 kevmoo@users.noreply.github.com [flutter_tools] Fix version cache poisoning from git environment variables (flutter/flutter#186595) 2026-05-26 bkonyi@google.com [Tool] Handle DTD connection failures gracefully in widget-preview (flutter/flutter#186952) 2026-05-25 engine-flutter-autoroll@skia.org Roll Skia from 9d1adb5f2427 to f4f294bdf98d (1 revision) (flutter/flutter#187056) 2026-05-25 engine-flutter-autoroll@skia.org Roll Skia from 4dd78179e6ec to 9d1adb5f2427 (1 revision) (flutter/flutter#187048) 2026-05-25 engine-flutter-autoroll@skia.org Roll Skia from 1f26101197bf to 4dd78179e6ec (4 revisions) (flutter/flutter#187044) 2026-05-24 engine-flutter-autoroll@skia.org Roll Skia from bbe9ccc2bdbf to 1f26101197bf (1 revision) (flutter/flutter#187016) 2026-05-24 engine-flutter-autoroll@skia.org Roll Fuchsia Linux SDK from nsgcNDlZOuweOvy3Q... to Itd2Jq_ZIABH2rW7B... (flutter/flutter#187032) 2026-05-23 engine-flutter-autoroll@skia.org Roll Dart SDK from 7e0f28eb5315 to 7eb54169841d (1 revision) (flutter/flutter#187005) 2026-05-23 engine-flutter-autoroll@skia.org Roll Dart SDK from 90e55fa88456 to 7e0f28eb5315 (1 revision) (flutter/flutter#186990) 2026-05-23 engine-flutter-autoroll@skia.org Roll Fuchsia Linux SDK from 6T6BY9PTftoG3vP_1... to nsgcNDlZOuweOvy3Q... (flutter/flutter#186984) 2026-05-23 chris@bracken.jp iOS] Migrate VSyncClient to a pure Obj-C implementation (#186166) (flutter/flutter#186935) 2026-05-23 30870216+gaaclarke@users.noreply.github.com Disables embedder_tests.cm for fuchsia (flutter/flutter#186969) 2026-05-23 engine-flutter-autoroll@skia.org Roll Dart SDK from b8414c46f6c7 to 90e55fa88456 (2 revisions) (flutter/flutter#186977) 2026-05-22 engine-flutter-autoroll@skia.org Roll Skia from 6fdb013d1953 to bbe9ccc2bdbf (1 revision) (flutter/flutter#186980) 2026-05-22 mdebbar@google.com [web] Fix cutoff text in WebParagraph (flutter/flutter#186819) 2026-05-22 1961493+harryterkelsen@users.noreply.github.com fix(web): Removes the iterative downscaling hack (flutter/flutter#186914) 2026-05-22 30870216+gaaclarke@users.noreply.github.com opts the linux embedder into sdf rendering (flutter/flutter#186909) 2026-05-22 engine-flutter-autoroll@skia.org Roll Skia from dae8778ca40d to 6fdb013d1953 (5 revisions) (flutter/flutter#186970) 2026-05-22 dacoharkes@google.com Fix hooks inputs outputs rebuilt (flutter/flutter#186701) 2026-05-22 30870216+gaaclarke@users.noreply.github.com adds linux impeller integration test for external textures (flutter/flutter#186759) 2026-05-22 kevmoo@users.noreply.github.com fix(flutter_tools): defensively catch DWDS unregistered service extension errors (flutter/flutter#186896) 2026-05-22 bdero@google.com [Impeller] Add golden harness support to the renderer test layer (flutter/flutter#186735) 2026-05-22 mdebbar@google.com [web] Remove image codecs from canvaskit_chromium (flutter/flutter#178133) 2026-05-22 30870216+gaaclarke@users.noreply.github.com opts all macos into wide gamut (flutter/flutter#186277) 2026-05-22 engine-flutter-autoroll@skia.org Roll Skia from 356185490a75 to dae8778ca40d (9 revisions) (flutter/flutter#186949) 2026-05-22 1598289+lukemmtt@users.noreply.github.com Filter out SwiftPM schemes when fetching schemes (flutter/flutter#186006) 2026-05-22 engine-flutter-autoroll@skia.org Roll Packages from 3754d04 to 69cf959 (1 revision) (flutter/flutter#186950) 2026-05-22 engine-flutter-autoroll@skia.org Roll Dart SDK from eca46bec956d to b8414c46f6c7 (2 revisions) (flutter/flutter#186944) 2026-05-22 30870216+gaaclarke@users.noreply.github.com Saves a DeviceHolderVK with the CommandPoolVK (flutter/flutter#186749) 2026-05-22 engine-flutter-autoroll@skia.org Roll Dart SDK from e0d509fd676e to eca46bec956d (1 revision) (flutter/flutter#186922) 2026-05-22 bkonyi@google.com [ Tool ] Stop generating widget preview scaffold under $TMP (flutter/flutter#186476) 2026-05-21 737941+loic-sharma@users.noreply.github.com Fix typo in StretchingOverscrollIndicator docs (flutter/flutter#186897) 2026-05-21 engine-flutter-autoroll@skia.org Roll Dart SDK from 28c7cb5a8e8d to e0d509fd676e (1 revision) (flutter/flutter#186903) 2026-05-21 jason-simmons@users.noreply.github.com Fix some issues in the integration between EmbedderExternalViewEmbedder and Impeller (flutter/flutter#184905) 2026-05-21 jason-simmons@users.noreply.github.com Fix a potential buffer overflow in the animated PNG decoder when parsing malformed fdAT chunks (flutter/flutter#186700) 2026-05-21 engine-flutter-autoroll@skia.org Roll Skia from 2ff20950975d to 356185490a75 (5 revisions) (flutter/flutter#186892) 2026-05-21 flar@google.com Add primitive shadows to rendering benchmark (flutter/flutter#186779) 2026-05-21 15619084+vashworth@users.noreply.github.com Move prefetchSwiftPackages to be per platform (flutter/flutter#186468) 2026-05-21 okorohelijah@google.com Upgrade iOS version (flutter/flutter#186889) ...
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Previously, the
widget_preview_scaffoldproject was generated under the system temporary directory ($TMP) to work around issues withflutter clean. However, generating the scaffold in$TMPmeant that the project was recreated on every run or could be lost, leading to unnecessary regeneration overhead and tracking issues.Move the generated
widget_preview_scaffoldproject from$TMPto a.widget_previewdirectory located directly under the project root. To support this change,WidgetPreviewGitignoreMigrationis introduced to automatically add.widget_preview/to the host project's.gitignore. In addition,kProjectRootPathis passed via DTD connection info to ensureWidgetInspectorServicecorrectly adds the project root to pub root directories. Finally, file watchers (LspPreviewDetectorandPreviewDetector) are updated to ignore the new.widget_previewdirectory.Fixes #179036