Dart SDK Changelog & Version Feature Guide (Dart 1.x to Modern Dart 3.x)

This skill provides an authoritative, structured guide to Dart language features, core library APIs, tooling changes, version requirements, experimental feature flags (--enable-experiment), static metaprogramming (Macros & Augmentations), and legacy modernization runbooks sourced directly from the official Dart SDK CHANGELOG.

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🎯 Parent Guide: How to Find the minSdk for Any Dart Feature or API

When writing or reviewing Dart code, selecting the correct minimum SDK lower bound (minSdk) in pubspec.yaml is essential to ensure syntax and core APIs compile across target environments.

1. Language Version vs. SDK Version

• Language Version (major.minor): In pubspec.yaml, the lower bound of environment.sdk (for example ^3.13.0 or >=3.12.0 <4.0.0) dictates which language grammar and compiler semantics are enabled.
  • Patch numbers (.1, .2) do not affect language grammar.
  • Using a Dart 3.13 feature (like Primary Constructors) requires sdk: '^3.13.0'.
• Core Library APIs: Methods and classes (for example Future.pause, List.unmodifiableOf) are added in specific SDK versions.
• Per-file override: A file can specify // @dart = 3.12 on line 1 to force an earlier language version.

2. Fast minSdk Language Feature Matrix

Feature / Syntax	Minimum SDK	Example Syntax	Reference
Primary Constructors	3.13.0	class Point(var int x, var int y); / this : assert(...)	3.13 Guide
Constructor Keyword Shorthands	3.13.0	new(this.x); / factory clone(...) => ...;	3.13 Guide
Private Named Parameters	3.12.0	Point({required this._x, required this._y});	3.12 Guide
Wildcard Variables (_)	3.7.0	var (_, b) = pair; / void fn(int _, int _)	3.7 Guide
Type Inference Using Bounds	3.7.0	Inferred types respect type parameter bounds	3.7 Guide
Digit Separators	3.6.0	1_000_000, 0x4000_0000, 0.000_001	3.6 Guide
Extension Types	3.3.0	extension type Meters(int value) {}	3.0-3.5 Guide
Private Field Promotion	3.2.0	if (_privateFinalField != null) { ... }	3.0-3.5 Guide
Records (Tuples)	3.0.0	(int, String) pair = (1, 'a');	3.0-3.5 Guide
Pattern Matching & Destructuring	3.0.0	var (a, b) = pair; / switch (val) { case ... }	3.0-3.5 Guide
Switch Expressions	3.0.0	var s = switch (e) { 0 => 'a', _ => 'b' };	3.0-3.5 Guide
If-Case Statements & Elements	3.0.0	if (json case {'id': int id}) ...	3.0-3.5 Guide
Sealed Classes & Exhaustiveness	3.0.0	sealed class State {}	3.0-3.5 Guide
Class Modifiers (base, interface, final)	3.0.0	interface class Api {} / final class Token {}	3.0-3.5 Guide
100% Sound Null Safety Enforced	3.0.0	Non-null-safe mode disallowed	3.0-3.5 Guide
Super-Initializer Parameters	2.17.0	SubClass(super.name, {super.key});	Dart 2 Milestones
Enhanced Enums	2.17.0	enum Status { ok(200); final int c; const Status(this.c); }	Dart 2 Milestones
Named Arguments Anywhere	2.17.0	fn(1, named: 'a', 2);	Dart 2 Milestones
Constructor Tear-Offs	2.15.0	List.filled, Point.new	Dart 2 Milestones
Triple-Shift Operator (>>>)	2.14.0	int result = a >>> b;	Dart 2 Milestones
Generic Type Aliases (typedef)	2.13.0	typedef JsonMap = Map<String, dynamic>;	Dart 2 Milestones
Sound Null Safety (?, late, !)	2.12.0	Sound static non-nullable types	Dart 2 Milestones
Extension Methods	2.7.0	extension on String { ... }	Dart 2 Milestones
Spread Operators (..., ...?)	2.3.0	[...list1, ...?maybeList]	Dart 2 Milestones
Collection if and for	2.3.0	[if (cond) a, for (var x in l) x * 2]	Dart 2 Milestones
Sound Type System & Optional new	2.0.0	Static sound types replace dynamic checks	Dart 2 Milestones

👉 For deep-dive and verification procedures, see How to Find minSdk and the Full Version Matrix.

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⚡ Subskill Spotlights

Subskill: Augmentations & Static Metaprogramming (Macros)

• Augmentation Syntax: Declare augment class, import augment, and wrap methods using augmented().
• Macro Phases: Understand Type, Declaration, and Definition macro execution in the analysis server.
• In-Memory Code Gen: Eliminate build_runner with zero-disk .g.dart pollution. 👉 Read the full Macros & Augmentations Guide.

Subskill: Experimental Features & Compiler Flags (--enable-experiment)

• Enabling Experiments: Configure analysis_options.yaml (analyzer.enable-experiment), CLI flags (dart --enable-experiment=...), and VS Code settings.
• Release Pipeline: Understand the graduation path across Beta preview, Stable-gated, and Stable-ungated tiers. 👉 Read the full Experimental Features Guide.

Subskill: Rescuing Legacy Codebases (Dart 1.x & Pre-2.12 to Modern Dart)

• Sound Null Safety Migration: Transform @required annotations, uninitialized nullable fields, and defensive runtime assertions.
• Dependency Upgrades: Modernize pubspec.yaml environment bounds and replace deprecated legacy packages (pedantic, tuple, etc.). 👉 Read the full Legacy Codebase Rescue Guide.

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📚 Table of Contents (TOC) & Version Archive

Release / Guide	Focus Area	Key Additions	Reference Document
Macros & Augmentations	Metaprogramming	augment, augmented(), import augment, @JsonCodable(), 3-phase macro pipeline	Macros & Augmentations Guide
Experimental Features	Compiler Flags	--enable-experiment, Beta preview vs stable-gated release tiers, graduation matrix	Experiments Guide
Legacy Rescue	Migration Runbook	Dart 1.x/2.x to Modern 3.x modernization pipeline, null-safety bridge, package replacements	Rescue Guide
Dart 3.14	FFI & JS Interop	NativeFinalizer.callback, fast primitive JS array conversions	3.14 Reference
Dart 3.13	Language & Runtime	Primary constructors, this constructor body, new/factory shorthands, Future.pause, synchronous isolates	3.13 Reference
Dart 3.12	Language & Tooling	Private named parameters (Point({this._x})), RegExp spans, dart run <pkg>@<ver>	3.12 Reference
Dart 3.11	Platform & Pub	Windows Unix domain sockets, Workspace globs (pkgs/*), dart pub cache gc	3.11 Reference
Dart 3.10	Extensibility & CLI	Analyzer plugins stable, Hooks (native assets) stable, dart install, @Deprecated constructors	3.10 Reference
Dart 3.9	Analysis & Pub	AOT analysis server, git tag version solving, null-safety assumptions in flow analysis	3.9 Reference
Dart 3.8	Formatter & Docs	Doc imports (@docImport), tall formatter trailing comma preservation, Iterable.withIterator	3.8 Reference
Dart 3.7	Language & Formatter	Wildcard variables (_), inference using bounds, tall style formatter default, legacy web deprecations	3.7 Reference
Dart 3.6	Language & Pub	Digit separators (1_000_000), Pub workspaces, dart pub bump	3.6 Reference
Dart 3.0 – 3.5	Foundation & Major Features	Records, Patterns, Switch Expressions, Sealed Classes, Class Modifiers, Extension Types, Field Promotion, Wasm	3.0–3.5 Reference
Dart 2.0 – 2.19	Historical Milestones	Sound Null Safety (2.12), Enhanced Enums & Super-Params (2.17), Extension Methods (2.7), Spreads (2.3), Sound Type System (2.0)	Dart 2 Milestones

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🛠️ Recommended Runbooks

1. Working with Augmentations & Macros

1. Review Macros & Augmentations Guide.
2. Wire original files with import augment 'foo.g.dart'; and augmentation files with augment library 'foo.dart';.
3. Use augment class, augment void method(), and call augmented() to wrap original logic.

2. Working with Experimental Feature Flags

1. Check if the feature has already graduated to stable in the active SDK before adding a flag.
2. If experimental, configure analysis_options.yaml under analyzer.enable-experiment: [name].
3. Pass --enable-experiment=name to dart run, dart test, flutter run, and flutter test.
4. Ensure experimental code is isolated so production packages remain publishable on pub.dev.

3. Modernizing / Rescuing a Legacy Codebase

1. Check current language version from pubspec.yaml environment block.
2. If pre-2.12, read the Legacy Rescue Guide.
3. Execute the 4-stage pipeline: syntax cleanup → sound null safety → dependency bump (sdk: ^3.5.0 or ^3.13.0) → Dart 3 modernization.

4. Answering "What's New in Dart X.Y"

1. Identify the requested version.
2. Read the corresponding reference document under references/.
3. Provide:
   • Language syntax changes with before/after code snippets.
   • Core library additions (dart:core, dart:async, dart:io, dart:js_interop, dart:isolate, dart:ffi).
   • Tooling and CLI features (dart analyze, dart format, dart pub, dart build).
   • Breaking changes and migration instructions.

5. Answering "How to find minSdk for X"

1. Check the Language Feature Matrix and How to Find minSdk Guide.
2. Specify the exact lower bound SDK constraint for pubspec.yaml (for example sdk: '^3.13.0').
3. Explain if the feature is a language grammar feature (requiring language version update) or a core library API.
4. Show how to verify using dart analyze.