Flutter 3.29–3.41 / Dart 3.7–3.11 Knowledge Patch

Claude's baseline knowledge covers Flutter through ~3.19 and Dart through ~3.3. This skill provides features from Flutter 3.29 (Feb 2025) and Dart 3.7 (Feb 2025) onwards.

Quick Reference — Dart Language

Feature	Version	Example
Null-aware elements	Dart 3.8	[?nullableValue] — omits if null
Dot shorthands	Dart 3.10	.center instead of MainAxisAlignment.center
Doc imports	Dart 3.8	/// @docImport 'dart:async';
Cross compilation	Dart 3.8	dart compile exe --target-os=linux --target-arch=arm64
Macros cancelled	Dart 3.7	@JsonCodable() discontinued; use json_serializable

See references/dart-language.md for syntax details and examples.

Quick Reference — Dart Tooling

Feature	Version	Detail
Pub git tags	Dart 3.9	tag_pattern: v{{version}} in pubspec
Pub workspace globs	Dart 3.11	workspace: [pkg/*]
dart pub cache gc	Dart 3.11	Clean unused cached packages
Build hooks (stable)	Dart 3.10	Bundle native C++/Rust/Swift code
Analyzer plugins	Dart 3.10	Custom lint rules in analysis_options.yaml
Flutter SDK upper bound	Dart 3.9	flutter: 3.33.0 enforced in root packages

See references/dart-tooling.md for configuration details.

Quick Reference — New & Changed Widgets

Widget	Version	Purpose
CupertinoSheetRoute	3.29	iOS draggable modal sheet
RoundedSuperellipseBorder	3.32	Squircle (iOS-style) corners
ClipRSuperellipse	3.32	Clip child to squircle shape
Expansible	3.32	Unstyled expand/collapse
RawMenuAnchor	3.32	Unstyled menu with keyboard nav
DropdownMenuFormField	3.35	M3 dropdown for forms
CupertinoExpansionTile	3.35	iOS expandable list tile
RadioGroup	3.35	Replaces Radio.groupValue (breaking)
CarouselView.builder	3.41	Dynamic carousel content
RepeatingAnimationBuilder	3.41	Declarative continuous animations
Badge.count(maxCount:)	3.38	Capped badge count ("99+")

See references/widgets.md for code examples.

Quick Reference — Platform, Web & Native

Feature	Version	Detail
Wasm without headers	3.29	Single-threaded by default, headers for multi-thread
Hot reload web	3.32→3.35	Experimental in 3.32, stable in 3.35
Web dev config	3.38	web_dev_config.yaml for host/port/proxy/headers
Predictive back (default)	3.38	Android back gesture with home preview
Platform-specific assets	3.41	platforms: [web] in pubspec assets
Content-sized views	3.41	Add-to-App auto-resize (isAutoResizable)
Multi-window (experimental)	3.41	Desktop popup/tooltip/dialog windows
UISceneDelegate (iOS)	3.38	Default on iOS; migration guide available
AGP 9 warning	3.41	Do NOT upgrade — plugin migration unsupported

See references/platform-web.md for configuration and migration details.

Quick Reference — Navigation & Animation

Feature	Version	Detail
FadeForwardsPageTransitionsBuilder	3.29	New M3 transition; default in 3.38
PredictiveBackPageTransitionBuilder	3.38	Default Android back transition
Navigator.popUntilWithResult	3.41	Pop multiple screens, return value
OverlayPortal.overlayChildLayoutBuilder	3.38	Render overlay in any ancestor Overlay
Fragment shader improvements	3.41	decodeImageFromPixelsSync, 128-bit textures

See references/navigation-animation.md for code examples.

Quick Reference — Accessibility

Feature	Version	Detail
SelectionListener	3.29	Get selection text from SelectionArea
SemanticsRole	3.32	Assign roles for screen readers (web)
SensitiveContent	3.35	Obscure during screen sharing (Android 15+)
SliverEnsureSemantics	3.35	Keep slivers in semantics tree when scrolled
SemanticsLabelBuilder	3.35	Combine data into single announcement
SliverSemantics	3.38	Annotate slivers for screen readers
CalendarDatePicker.calendarDelegate	3.32	Non-Gregorian calendar support

See references/accessibility.md for code examples.

Breaking Changes

Change	Version	Migration
Radio.groupValue deprecated	3.35	Use RadioGroup wrapper
SnackBar no auto-dismiss with action	3.38	User must dismiss manually
Default Android transition changed	3.38	Now FadeForwardsPageTransitionsBuilder
UISceneDelegate default on iOS	3.38	See migration guide
Min Android SDK → API 24	3.35	Android 7+ required
Gradle 8.7.0, AGP 8.6.0, Java 17	3.35	Update build tools
Legacy web libs deprecated	Dart 3.7	Use dart:js_interop + package:web
Merged threads on Linux desktop	3.41	UI + platform threads merged by default

Reference Files

File	Contents
dart-language.md	Null-aware elements, dot shorthands, doc imports, cross compilation
dart-tooling.md	Pub git tags, workspace globs, build hooks, analyzer plugins
widgets.md	CupertinoSheet, squircles, Expansible, RadioGroup, CarouselView
platform-web.md	Hot reload web, predictive back, platform assets, multi-window
navigation-animation.md	Page transitions, popUntilWithResult, RepeatingAnimationBuilder
accessibility.md	SemanticsRole, SliverSemantics, SensitiveContent, SelectionListener

Critical Examples

Dot Shorthands (Dart 3.10+ / Flutter 3.38+)

Column(
  mainAxisAlignment: .center,
  children: [
    Padding(padding: .all(8.0), child: Text('Hi')),
  ],
)

Null-Aware Elements (Dart 3.8+)

List<String> names = [?nullableName, ?user?.displayName];

Squircle Container

Container(
  decoration: ShapeDecoration(shape: RoundedSuperellipseBorder(
    borderRadius: BorderRadius.circular(20),
  )),
)

RadioGroup (Flutter 3.35+, Breaking)

RadioGroup<String>(
  groupValue: selected,
  onChanged: (value) => setState(() => selected = value),
  children: [Radio<String>(value: 'a'), Radio<String>(value: 'b')],
)

Platform-Specific Assets

flutter:
  assets:
    - path: assets/logo.png
    - path: assets/web_worker.js
      platforms: [web]