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v3.126.0 2025-12-29

Flutter Widget Preview

• #5840/#5814: To improve startup performance, the widget preview now starts on first access rather than at startup. This can be controlled with a new setting dart.flutterWidgetPreview that accepts "startLazily" (default), "startEagerly" (starts at startup when a Flutter project is present) and "disabled".

Testing

• #5842/#5833: When running a batch of tests from the Test Explorer requires launching multiple sequential debug sessions, a progress notification will be shown indicating the number of sessions with the ability to cancel the entire batch.
• #5831/#5834: Deleting a test no longer sometimes causes the next test marker to move to the incorrect line.

Misc

• #5841: A warning is now shown that Dart 3.1 / Flutter 3.13 will become unsupported in a future release. See the SDK Compatibility page for details of which extension versions support which SDKs if you need to continue to use an unsupported SDK.
• #5848: Some unexpected conditions that trigger extension restarts will now show warning notifications encouraging filing a GitHub issue for investigation.
• #5830: Updated to LSP client v10.0.0-next.18 and enabled delayOpenNotifications for improved performance. This change was reverted pending a fix in the VS Code LSP client.

Features/Fixes Enabled with Future SDKs

The following items depend on changes to the Dart/Flutter SDKs that have not yet been released to stable channels. They may be available to test in the current beta/master channels and will show up in future SDK releases.

• #5832: formatOnType no longer triggers when typing ; or } in places that are not ends of statements/blocks (such as strings, comments, patterns).
• #5602: formatOnType no longer triggers when typing ; inside an enhanced enum without a constructor, which caused the semicolon to be removed.
• #5808: The Flutter Sidebar no longer stops responding after the PC wakes from sleep. Instead, a “Reconnecting…” notification will be shown while re-connecting to DTD.

Upstream Issues

Some feature requests and fixes require new features and fixes in upstream projects like VS Code and LSP which use counts of 👍s on those issues to help gauge demand. The Dart-Code website now lists some of the most significant upstream issues with a description of the feature/fix they would enable. Please consider reviewing this list and adding your 👍 to any GitHub issues relevant to features you’d like to see!

https://dartcode.org/upstream-issues/