Migration Guide for Updated Material 3 Progress Indicators

src/content/release/breaking-changes/index.md

@@ -42,6 +42,7 @@ release, and listed in alphabetical order:
 * [Deprecate `TextField.canRequestFocus`][]
 * [Set default for SystemUiMode to Edge-to-Edge][]
 * [Deprecate `ThemeData.dialogBackgroundColor` in favor of `DialogThemeData.backgroundColor`][]
+* [Updated Material 3 Progress Indicators][]
 
 [`ImageFilter.blur` default tile mode automatic selection]: /release/breaking-changes/image-filter-blur-tilemode
 [Localized messages are generated into source, not a synthetic package]: /release/breaking-changes/flutter-generate-i10n-source
@@ -52,6 +53,7 @@ release, and listed in alphabetical order:
 [Deprecate `TextField.canRequestFocus`]: /release/breaking-changes/can-request-focus
 [Set default for SystemUiMode to Edge-to-Edge]: /release/breaking-changes/default-systemuimode-edge-to-edge
 [Deprecate `ThemeData.dialogBackgroundColor` in favor of `DialogThemeData.backgroundColor`]: /release/breaking-changes/deprecate-themedata-dialogbackgroundcolor
+[Updated Material 3 Progress Indicators]: /release/breaking-changes/updated-material-3-progress-indicators
 
 <a id="released-in-flutter-324" aria-hidden="true"></a>
 ### Released in Flutter 3.24

src/content/release/breaking-changes/updated-material-3-progress-indicators.md

@@ -0,0 +1,90 @@
+---
+title: Updated Material 3 Progress Indicators
+description: >-
+  The `LinearProgressIndicator` and `CircularProgressIndicator` widgets
+  have been updated to match the Material 3 Design specifications.
+---
+
+## Summary
+
+The `LinearProgressIndicator` and `CircularProgressIndicator` have been updated
+to match the Material 3 Design specifications. The `LinearProgressIndicator`
+changes include a gap between the active and inactive tracks, a stop indicator,
+and rounded corners. The `CircularProgressIndicator` changes include a gap
+between the active and inactive tracks and rounded stroke cap.
+
+## Context
+
+The Material 3 Design specifications for the `LinearProgressIndicator` and
+`CircularProgressIndicator` were updated in December 2023. To opt into the 2024
+design specifications, set the `LinearProgressIndicator.year2023` and
+`CircularProgressIndicator.year2023` flags to `false`. This is done to
+ensure that existing apps are not affected by the updated design spec.
+
+## Description of change
+
+The `LinearProgressIndicator` and `CircularProgressIndicator` widgets each have
+a `year2023` flag that can be set to `false` to opt into the updated design
+spec. The default value for the `year2023` flag is `true`, which means that
+the progress indicators use the 2023 design spec.
+
+When [`LinearProgressIndicator.year2023`][] is set to `false`, the progress
+indicator will have gaps between active and inactive tracks, a stop indicator,
+and rounded corners. If the `LinearProgressIndicator` is indeterminate, the stop
+indicator will not be shown.
+
+When [`CircularProgressIndicator.year2023`][] is set to `false`, the progress
+indicator will have a track gap and rounded stroke cap.
+
+## Migration guide
+
+To opt into the updated design spec for the `LinearProgressIndicator`, set the
+`year2023` flag to `false`:
+
+```dart
+LinearProgressIndicator(
+  year2023: false,
+  value: 0.5,
+),
+```
+
+To opt into the updated design spec for the `CircularProgressIndicator`, set
+the `year2023` flag to `false`:
+
+```dart
+CircularProgressIndicator(
+  year2023: false,
+  value: 0.5,
+),
+```
+
+## Timeline
+
+Landed in version: v3.27.0-0.2.pre.<br>
+In stable release: TBD
+
+## References
+
+API documentation:
+
+- [`LinearProgressIndicator`][]
+- [`CircularProgressIndicator`][]
+- [`LinearProgressIndicator.year2023`][]
+- [`CircularProgressIndicator.year2023`][]
+
+Relevant issues:
+
+- [Update both `ProgressIndicator` for Material 3 redesign][]
+
+Relevant PRs:
+
+- [Update Material 3 `LinearProgressIndicator` for new visual style][]
+- [Update Material 3 `CircularProgressIndicator` for new visual style][]
+
+[`LinearProgressIndicator`]: {{site.api}}/flutter/material/LinearProgressIndicator-class.html
+[`CircularProgressIndicator`]: {{site.api}}/flutter/material/CircularProgressIndicator-class.html
+[`LinearProgressIndicator.year2023`]: {{site.api}}/flutter/material/LinearProgressIndicator/year2023.html
+[`CircularProgressIndicator.year2023`]: {{site.api}}/flutter/material/CircularProgressIndicator/year2023.html
+[Update both `ProgressIndicator` for Material 3 redesign]: {{site.repo.flutter}}/issues/141340
+[Update Material 3 `LinearProgressIndicator` for new visual style]: {{site.repo.flutter}}/pull/141340
+[Update Material 3 `CircularProgressIndicator` for new visual style]: {{site.repo.flutter}}/pull/141340