diff --git a/.github/workflows/dart.yaml b/.github/workflows/dart.yaml
index d992b209..264d8c46 100644
--- a/.github/workflows/dart.yaml
+++ b/.github/workflows/dart.yaml
@@ -6,12 +6,12 @@ on:
     branches: [main]
     paths:
       - ".github/workflows/dart.yaml"
-      - "executors/dart**"
+      - "executors/dart/**"
   push:
     branches: [main]
     paths:
       - ".github/workflows/dart.yaml"
-      - "executors/dart**"
+      - "executors/dart/**"
   schedule:
     - cron: "0 0 * * 0" # weekly
 
@@ -28,9 +28,9 @@ jobs:
     steps:
       - uses: actions/checkout@c85c95e3d7251135ab7dc9ce3241c5835cc595a9
 
-      - uses: dart-lang/setup-dart@e51d8e571e22473a2ddebf0ef8a2123f0ab2c02c
+      - uses: dart-lang/setup-dart@a73965b3c99b30eb092908ce56c429eff91f9634
         with:
-          sdk: 3.10.0
+          sdk: 3.12.0
 
       - run: dart pub get
 
diff --git a/.github/workflows/e2e.yml b/.github/workflows/e2e.yml
index b6116414..9ca42fdb 100644
--- a/.github/workflows/e2e.yml
+++ b/.github/workflows/e2e.yml
@@ -23,7 +23,7 @@ jobs:
     steps:
       - name: Install prerequisites
         run: |
-          apt-get update && apt-get install -y sudo python3 wget unzip logrotate curl jq python3-requests python3-jsonschema build-essential clang maven
+          apt-get update && apt-get install -y sudo python3 wget unzip logrotate curl jq python3-requests python3-jsonschema build-essential clang maven git
       - name: Free up some disk space
         run: |
           echo "Available storage before:"
@@ -49,9 +49,9 @@ jobs:
           path: gh-cache
           key: ${{ runner.os }}-icu4c-binaries
       - name: Setup version of Dart
-        uses: dart-lang/setup-dart@v1
+        uses: dart-lang/setup-dart@a73965b3c99b30eb092908ce56c429eff91f9634
         with:
-          sdk: 3.10.0
+          sdk: 3.12.0
       - name: Set version of Rust
         uses: actions-rs/toolchain@v1
         with:
diff --git a/executors/dart/bin/executor.dart b/executors/dart/bin/executor.dart
index 5973107e..5365f056 100644
--- a/executors/dart/bin/executor.dart
+++ b/executors/dart/bin/executor.dart
@@ -7,6 +7,7 @@ import 'package:collection/collection.dart';
 import 'package:dart_executor/collator.dart';
 import 'package:dart_executor/datetime_format.dart';
 import 'package:dart_executor/lang_names.dart';
+import 'package:dart_executor/likely_subtags.dart';
 import 'package:dart_executor/list_format.dart';
 import 'package:dart_executor/numberformat.dart';
 import 'package:dart_executor/plural_rules.dart';
@@ -56,14 +57,9 @@ void main() {
           TestTypes.decimal_fmt => testDecimalFormatWrapped(line),
           TestTypes.number_fmt => testDecimalFormatWrapped(line),
           TestTypes.datetime_fmt => testDateTimeFmt(line),
-          TestTypes.display_names => throw UnimplementedError(
-            'display_names is not supported yet',
-          ),
+          TestTypes.display_names => testLangNames(line),
           TestTypes.lang_names => testLangNames(line),
-          // TestTypes.likely_subtags => testLikelySubtags(line),
-          TestTypes.likely_subtags => throw UnimplementedError(
-            'likely_subtags is not supported yet, as the Locale object is not yet migrated to ICU4X',
-          ),
+          TestTypes.likely_subtags => testLikelySubtags(line),
           TestTypes.list_fmt => testListFmt(line),
           TestTypes.plural_rules => testPluralRules(line),
           null => throw ArgumentError.value(
diff --git a/executors/dart/bin/make_runnable_by_node.dart b/executors/dart/bin/make_runnable_by_node.dart
index 5df91aab..9f88ee0b 100644
--- a/executors/dart/bin/make_runnable_by_node.dart
+++ b/executors/dart/bin/make_runnable_by_node.dart
@@ -22,6 +22,10 @@ Future<void> main(List<String> args) async {
       name: 'testPluralRules',
       argNames: ['encoded'],
     ),
+    'likely_subtags': ExportFunction(
+      name: 'testLikelySubtags',
+      argNames: ['encoded'],
+    ),
     'list_format': ExportFunction(name: 'testListFmt', argNames: ['encoded']),
     'datetimeformat': ExportFunction(
       name: 'testDateTimeFmt',
diff --git a/executors/dart/bin/web_wrappers/likely_subtags_executor.dart b/executors/dart/bin/web_wrappers/likely_subtags_executor.dart
new file mode 100644
index 00000000..aeb0e1b6
--- /dev/null
+++ b/executors/dart/bin/web_wrappers/likely_subtags_executor.dart
@@ -0,0 +1,5 @@
+import 'package:dart_executor/likely_subtags.dart';
+
+void main(List<String> args) {
+  testLikelySubtags(args.first);
+}
diff --git a/executors/dart/lib/datetime_format.dart b/executors/dart/lib/datetime_format.dart
index 9eb57b7d..6e9bdaed 100644
--- a/executors/dart/lib/datetime_format.dart
+++ b/executors/dart/lib/datetime_format.dart
@@ -119,15 +119,26 @@ String testDateTimeFmt(String jsonEncoded) {
             locale,
             timePrecision,
           );
+    final offset = offsetSeconds != null
+        ? Duration(seconds: offsetSeconds)
+        : Duration.zero;
+    final dateToFormat = testDate!.add(offset);
+
+    final isZoned =
+        formatter is DateTimeFormatter &&
+        timeZoneName != null &&
+        ((semanticSkeleton ?? '').contains('Z') ||
+            timeStyle == 'full' ||
+            testOptionsJson.containsKey('zoneStyle') ||
+            (skeleton != null && RegExp(r'[zvOV]').hasMatch(skeleton)));
+
     String formattedDt;
-    if (formatter is DateTimeFormatter &&
-        (semanticSkeleton ?? '').contains('Z')) {
-      final offset = Duration(seconds: offsetSeconds!);
+    if (isZoned) {
       final zoneStyle = testOptionsJson['zoneStyle'] as String?;
       final zonedFormatter = getZonedFormatter(zoneStyle, formatter, skeleton);
-      formattedDt = zonedFormatter.format(testDate!.add(offset), timeZoneName!);
+      formattedDt = zonedFormatter.format(dateToFormat, timeZoneName);
     } else {
-      formattedDt = formatter.format(testDate!);
+      formattedDt = formatter.format(dateToFormat);
     }
     returnJson['result'] = formattedDt;
   } on Exception catch (e) {
@@ -137,8 +148,8 @@ String testDateTimeFmt(String jsonEncoded) {
   }
   returnJson['actual_options'] = {
     'locale': locale.toString(),
-    if (dateStyle != null) 'dateStyle': dateStyle,
-    if (timeStyle != null) 'timeStyle': timeStyle,
+    'dateStyle': ?dateStyle,
+    'timeStyle': ?timeStyle,
     if (yearStyle != null) 'yearStyle': yearStyle.name,
     if (calendar != null) 'calendar': calendar.jsName,
   };
@@ -234,11 +245,11 @@ ZonedDateTimeFormatter getZonedFormatter(
   return switch (timeZoneStyle) {
     'short' => formatter.withTimeZoneShort(),
     'specific' => formatter.withTimeZoneShort(),
-    'full' => formatter.withTimeZoneLongGeneric(),
+    'full' => formatter.withTimeZoneLong(),
     'generic' => formatter.withTimeZoneLongGeneric(),
     'location' => formatter.withTimeZoneShort(),
-    'offset' => formatter.withTimeZoneLongGeneric(),
-    null => formatter.withTimeZoneLongGeneric(),
+    'offset' => formatter.withTimeZoneLongOffset(),
+    null => formatter.withTimeZoneLong(),
     String() => throw Exception('Unknown time zone style `$timeZoneStyle`'),
   };
 }
@@ -250,7 +261,6 @@ DateTimeFormatter getFormatterForStyle(
   Locale locale,
   TimePrecision? timePrecision,
 ) {
-  print((dateStyle, timeStyle, yearStyle));
   return switch ((dateStyle, timeStyle, yearStyle)) {
     ('medium', null, null) => DateTimeFormat.yearMonthDay(
       locale: locale,
diff --git a/executors/dart/lib/likely_subtags.dart b/executors/dart/lib/likely_subtags.dart
new file mode 100644
index 00000000..e161dcd9
--- /dev/null
+++ b/executors/dart/lib/likely_subtags.dart
@@ -0,0 +1,29 @@
+import 'dart:convert';
+
+import 'package:intl4x/locale.dart';
+
+String testLikelySubtags(String jsonEncoded) {
+  final json = jsonDecode(jsonEncoded) as Map<String, dynamic>;
+  final label = json['label'];
+  final localeStr = json['locale'] as String;
+  final option = json['option'] as String;
+
+  final returnJson = <String, dynamic>{'label': label};
+
+  try {
+    final locale = Locale.parse(localeStr);
+    if (option == 'maximize') {
+      returnJson['result'] = locale.maximize().toLanguageTag();
+    } else if (option == 'minimize' || option == 'minimizeFavorRegion') {
+      returnJson['result'] = locale.minimize().toLanguageTag();
+    } else {
+      returnJson['error_type'] = 'unsupported';
+      returnJson['unsupported'] = 'Option $option not supported';
+      return jsonEncode(returnJson);
+    }
+  } catch (e) {
+    returnJson['error'] = e.toString();
+  }
+
+  return jsonEncode(returnJson);
+}
diff --git a/executors/dart/lib/plural_rules.dart b/executors/dart/lib/plural_rules.dart
index 82da0ca1..7a319546 100644
--- a/executors/dart/lib/plural_rules.dart
+++ b/executors/dart/lib/plural_rules.dart
@@ -80,8 +80,16 @@ String testPluralRules(String jsonEncoded) {
       : PluralRules(locale: locale);
 
   try {
-    final result = pluralRules.select(sample);
-    returnJson['result'] = result.name;
+    final result = pluralRules.select(
+      sample,
+      zero: 'zero',
+      one: 'one',
+      two: 'two',
+      few: 'few',
+      many: 'many',
+      other: 'other',
+    );
+    returnJson['result'] = result;
   } catch (error) {
     returnJson['error'] = 'PLURAL RULES UNKNOWN ERROR: ${error.toString()}';
   }
diff --git a/executors/dart/lib/version.dart b/executors/dart/lib/version.dart
index 012e4e6f..96db806b 100644
--- a/executors/dart/lib/version.dart
+++ b/executors/dart/lib/version.dart
@@ -1,2 +1,2 @@
 /// This file is autogenerated by bin/set_version.dart, do not modify manually.
-const intl4xVersion = '0.17.0';
+const intl4xVersion = '1.0.0-alpha.3-wip';
diff --git a/executors/dart/out/executor.js b/executors/dart/out/executor.js
index 9fb14a78..2c8b95e1 100644
--- a/executors/dart/out/executor.js
+++ b/executors/dart/out/executor.js
@@ -28,6 +28,8 @@ let datetime_fmt = require('./datetimeformat.js');
 
 let list_fmt = require('./list_format.js');
 
+let likely_subtags = require('./likely_subtags.js');
+
 const { dartVersion } = require('./version.js')
 
 /**
@@ -136,7 +138,7 @@ rl.on('line', function (line) {
           outputLine = collator.testCollation(parsedJson);
         } else if (test_type == "decimal_fmt" || test_type == "number_fmt") {
           outputLine = numberformatter.testDecimalFormat(parsedJson, doLogInput > 0, process.version);
-        } else if (test_type == "language_display_name" || test_type == "lang_names") {
+        } else if (test_type == "language_display_name" || test_type == "lang_names" || test_type == "display_names") {
           outputLine = lang_names.testLangNames(parsedJson);
         } else if (test_type == "plural_rules") {
           outputLine = plural_rules.testPluralRules(parsedJson);
@@ -144,6 +146,8 @@ rl.on('line', function (line) {
           outputLine = datetime_fmt.testDateTimeFmt(parsedJson, doLogInput > 0, process.version);
         } else if (test_type == "list_fmt") {
           outputLine = list_fmt.testListFmt(parsedJson);
+        } else if (test_type == "likely_subtags") {
+          outputLine = likely_subtags.testLikelySubtags(parsedJson);
         }  else {
           outputLine = {
             'error': 'unknown test type', 'testId': testId,
diff --git a/executors/dart/out/likely_subtags.js b/executors/dart/out/likely_subtags.js
new file mode 100644
index 00000000..dfa074ad
--- /dev/null
+++ b/executors/dart/out/likely_subtags.js
@@ -0,0 +1,6 @@
+var tools = require('./likely_subtagsDart');
+module.exports = {
+    testLikelySubtags: function (json) {
+        return JSON.parse(tools.testLikelySubtags(JSON.stringify(json)));
+    }
+};
diff --git a/executors/dart/out/version.js b/executors/dart/out/version.js
index 9d756391..f6fc6b28 100644
--- a/executors/dart/out/version.js
+++ b/executors/dart/out/version.js
@@ -1,2 +1,2 @@
-const dartVersion = "0.17.0";
+const dartVersion = "1.0.0-alpha.3-wip";
 module.exports = { dartVersion };
diff --git a/executors/dart/pubspec.lock b/executors/dart/pubspec.lock
index 539925d1..ba919704 100644
--- a/executors/dart/pubspec.lock
+++ b/executors/dart/pubspec.lock
@@ -5,18 +5,18 @@ packages:
     dependency: transitive
     description:
       name: _fe_analyzer_shared
-      sha256: "5b7468c326d2f8a4f630056404ca0d291ade42918f4a3c6233618e724f39da8e"
+      sha256: f6526c100095fd63a916824e3da344bbbd50c25c8f56bcd52d13c59d35bbe422
       url: "https://pub.dev"
     source: hosted
-    version: "92.0.0"
+    version: "104.0.0"
   analyzer:
     dependency: transitive
     description:
       name: analyzer
-      sha256: "70e4b1ef8003c64793a9e268a551a82869a8a96f39deb73dea28084b0e8bf75e"
+      sha256: "6c6d751533496152e78f71c46ad001260c5e74e0f9ec1f1cbc165a0467c086d6"
       url: "https://pub.dev"
     source: hosted
-    version: "9.0.0"
+    version: "14.0.0"
   args:
     dependency: transitive
     description:
@@ -29,10 +29,10 @@ packages:
     dependency: transitive
     description:
       name: async
-      sha256: "758e6d74e971c3e5aceb4110bfd6698efc7f501675bcfe0c775459a8140750eb"
+      sha256: e2eb0491ba5ddb6177742d2da23904574082139b07c1e33b8503b9f46f3e1a37
       url: "https://pub.dev"
     source: hosted
-    version: "2.13.0"
+    version: "2.13.1"
   boolean_selector:
     dependency: transitive
     description:
@@ -61,10 +61,10 @@ packages:
     dependency: transitive
     description:
       name: code_assets
-      sha256: "83ccdaa064c980b5596c35dd64a8d3ecc68620174ab9b90b6343b753aa721687"
+      sha256: cfd4f5f575a49c5f10ca856e9846073f1e6c3ee94912377eea5f6cefc5272941
       url: "https://pub.dev"
     source: hosted
-    version: "1.0.0"
+    version: "2.0.0"
   collection:
     dependency: "direct main"
     description:
@@ -85,10 +85,10 @@ packages:
     dependency: transitive
     description:
       name: coverage
-      sha256: "5da775aa218eaf2151c721b16c01c7676fbfdd99cebba2bf64e8b807a28ff94d"
+      sha256: "956a3de0725ca232ad353565a8290d3357592bf4250f6f298a185e2d949c5d3d"
       url: "https://pub.dev"
     source: hosted
-    version: "1.15.0"
+    version: "1.15.1"
   crypto:
     dependency: transitive
     description:
@@ -101,10 +101,10 @@ packages:
     dependency: transitive
     description:
       name: ffi
-      sha256: "289279317b4b16eb2bb7e271abccd4bf84ec9bdcbe999e278a94b804f5630418"
+      sha256: "6d7fd89431262d8f3125e81b50d3847a091d846eafcd4fdb88dd06f36d705a45"
       url: "https://pub.dev"
     source: hosted
-    version: "2.1.4"
+    version: "2.2.0"
   file:
     dependency: transitive
     description:
@@ -133,10 +133,10 @@ packages:
     dependency: transitive
     description:
       name: hooks
-      sha256: "5d309c86e7ce34cd8e37aa71cb30cb652d3829b900ab145e4d9da564b31d59f7"
+      sha256: eaac480a35ec0814146c2c48d96aaa829e0e44a7662c88ae84c9edf4bc35651f
       url: "https://pub.dev"
     source: hosted
-    version: "1.0.0"
+    version: "2.2.0"
   http:
     dependency: transitive
     description:
@@ -162,21 +162,22 @@ packages:
     source: hosted
     version: "4.1.2"
   icu4x:
-    dependency: transitive
+    dependency: "direct main"
     description:
       name: icu4x
-      sha256: "8c2f3ed5f860c68be13076e43685f49330956a8a8c351c9af7920606be411368"
+      sha256: "6890e55223422b5bbde95060202d7438dba88d3347ec3598f91d73ff45e64c15"
       url: "https://pub.dev"
     source: hosted
-    version: "2.1.0-dev.1"
+    version: "2.3.1"
   intl4x:
     dependency: "direct main"
     description:
-      name: intl4x
-      sha256: "30170321747219904977b4826dbd5156e34f407876f87695d8b8167da5955d20"
-      url: "https://pub.dev"
-    source: hosted
-    version: "0.17.0"
+      path: "pkgs/intl4x"
+      ref: a3c72590b83f60c3631ece8064d7990840eed187
+      resolved-ref: a3c72590b83f60c3631ece8064d7990840eed187
+      url: "https://github.com/dart-lang/i18n.git"
+    source: git
+    version: "1.0.0-alpha.3-wip"
   io:
     dependency: transitive
     description:
@@ -189,18 +190,18 @@ packages:
     dependency: transitive
     description:
       name: json_annotation
-      sha256: "1ce844379ca14835a50d2f019a3099f419082cfdd231cd86a142af94dd5c6bb1"
+      sha256: "2a743920d81b7910627f68ee2c9ac1fc0bfee32b9fc3403587d7c6791ca12f80"
       url: "https://pub.dev"
     source: hosted
-    version: "4.9.0"
+    version: "4.12.0"
   lints:
     dependency: "direct dev"
     description:
       name: lints
-      sha256: a5e2b223cb7c9c8efdc663ef484fdd95bb243bff242ef5b13e26883547fce9a0
+      sha256: "12f842a479589fea194fe5c5a3095abc7be0c1f2ddfa9a0e76aed1dbd26a87df"
       url: "https://pub.dev"
     source: hosted
-    version: "6.0.0"
+    version: "6.1.0"
   logging:
     dependency: transitive
     description:
@@ -213,18 +214,18 @@ packages:
     dependency: transitive
     description:
       name: matcher
-      sha256: "12956d0ad8390bbcc63ca2e1469c0619946ccb52809807067a7020d57e647aa6"
+      sha256: "31bd099b47c10cd1aeb55146a2d46ce0277630ecef3f7dae54ad7873f36696cd"
       url: "https://pub.dev"
     source: hosted
-    version: "0.12.18"
+    version: "0.12.20"
   meta:
     dependency: "direct dev"
     description:
       name: meta
-      sha256: "23f08335362185a5ea2ad3a4e597f1375e78bce8a040df5c600c8d3552ef2394"
+      sha256: "307249ce4ff29d58a18e97f6345f539382eb9c9c29ecda628900f31de0443dd9"
       url: "https://pub.dev"
     source: hosted
-    version: "1.17.0"
+    version: "1.19.0"
   mime:
     dependency: transitive
     description:
@@ -237,10 +238,10 @@ packages:
     dependency: transitive
     description:
       name: native_toolchain_c
-      sha256: "89e83885ba09da5fdf2cdacc8002a712ca238c28b7f717910b34bcd27b0d03ac"
+      sha256: "9d233b6f2d9c52e1a2b5fbe70451d2c10ac674d3bb419d0ec8de14989d437c26"
       url: "https://pub.dev"
     source: hosted
-    version: "0.17.4"
+    version: "0.19.4"
   node_preamble:
     dependency: "direct main"
     description:
@@ -253,10 +254,10 @@ packages:
     dependency: transitive
     description:
       name: package_config
-      sha256: f096c55ebb7deb7e384101542bfba8c52696c1b56fca2eb62827989ef2353bbc
+      sha256: ffcf4cf3d6c0b74ac43708d9f56625506e8a68aa935abe9d267a7330f320eb5d
       url: "https://pub.dev"
     source: hosted
-    version: "2.2.0"
+    version: "3.0.0"
   path:
     dependency: transitive
     description:
@@ -265,6 +266,14 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "1.9.1"
+  platform:
+    dependency: transitive
+    description:
+      name: platform
+      sha256: "5d6b1b0036a5f331ebc77c850ebc8506cbc1e9416c27e59b439f917a902a4984"
+      url: "https://pub.dev"
+    source: hosted
+    version: "3.1.6"
   pool:
     dependency: transitive
     description:
@@ -273,6 +282,14 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "1.5.2"
+  process:
+    dependency: transitive
+    description:
+      name: process
+      sha256: "4242ba3508d37e01808bdf71ad1d5bb93a8d671bf2e7450e6b1b353fb0808891"
+      url: "https://pub.dev"
+    source: hosted
+    version: "5.0.6"
   pub_semver:
     dependency: transitive
     description:
@@ -293,10 +310,10 @@ packages:
     dependency: transitive
     description:
       name: record_use
-      sha256: d3d59b18ca7aa1ce689bb3b3fd982bbebdfcd9e89f977576486a55e3b0f19a27
+      sha256: "1cb8564af8d43b464294411db9217f5ec04891c6f22ee2c32d73ae05e88a6bd2"
       url: "https://pub.dev"
     source: hosted
-    version: "0.4.2"
+    version: "1.1.1"
   shelf:
     dependency: transitive
     description:
@@ -349,10 +366,10 @@ packages:
     dependency: transitive
     description:
       name: source_span
-      sha256: "254ee5351d6cb365c859e20ee823c3bb479bf4a293c22d17a9f1bf144ce86f7c"
+      sha256: "56a02f1f4cd1a2d96303c0144c93bd6d909eea6bee6bf5a0e0b685edbd4c47ab"
       url: "https://pub.dev"
     source: hosted
-    version: "1.10.1"
+    version: "1.10.2"
   stack_trace:
     dependency: transitive
     description:
@@ -389,34 +406,34 @@ packages:
     dependency: "direct dev"
     description:
       name: test
-      sha256: "77cc98ea27006c84e71a7356cf3daf9ddbde2d91d84f77dbfe64cf0e4d9611ae"
+      sha256: "0d5ba5602ec3baa28c8ce365e1efc5575969c765f45c554a3e167dc7945b9c30"
       url: "https://pub.dev"
     source: hosted
-    version: "1.28.0"
+    version: "1.31.2"
   test_api:
     dependency: transitive
     description:
       name: test_api
-      sha256: "19a78f63e83d3a61f00826d09bc2f60e191bf3504183c001262be6ac75589fb8"
+      sha256: "475610b2aa23c19687cce2961e44b0cc57cafe220f67c2b80201231b2a07fbe7"
       url: "https://pub.dev"
     source: hosted
-    version: "0.7.8"
+    version: "0.7.13"
   test_core:
     dependency: transitive
     description:
       name: test_core
-      sha256: f1072617a6657e5fc09662e721307f7fb009b4ed89b19f47175d11d5254a62d4
+      sha256: a39c204a4fc7a7ccb04a2b985e359fda3cc37e45e0b8ac61c3fb1a05aa832132
       url: "https://pub.dev"
     source: hosted
-    version: "0.6.14"
+    version: "0.6.19"
   timezone:
     dependency: transitive
     description:
       name: timezone
-      sha256: dd14a3b83cfd7cb19e7888f1cbc20f258b8d71b54c06f79ac585f14093a287d1
+      sha256: "981d1020d6ef8fe1e7b3de5054e5b25579ae7c403d7734adc508ffc47668e9cb"
       url: "https://pub.dev"
     source: hosted
-    version: "0.10.1"
+    version: "0.11.1"
   typed_data:
     dependency: transitive
     description:
@@ -429,18 +446,18 @@ packages:
     dependency: transitive
     description:
       name: vm_service
-      sha256: "45caa6c5917fa127b5dbcfbd1fa60b14e583afdc08bfc96dda38886ca252eb60"
+      sha256: "0016aef94fc66495ac78af5859181e3f3bf2026bd8eecc72b9565601e19ab360"
       url: "https://pub.dev"
     source: hosted
-    version: "15.0.2"
+    version: "15.2.0"
   watcher:
     dependency: transitive
     description:
       name: watcher
-      sha256: f52385d4f73589977c80797e60fe51014f7f2b957b5e9a62c3f6ada439889249
+      sha256: "1398c9f081a753f9226febe8900fce8f7d0a67163334e1c94a2438339d79d635"
       url: "https://pub.dev"
     source: hosted
-    version: "1.2.0"
+    version: "1.2.1"
   web:
     dependency: transitive
     description:
@@ -482,4 +499,4 @@ packages:
     source: hosted
     version: "3.1.3"
 sdks:
-  dart: ">=3.10.0 <4.0.0"
+  dart: ">=3.12.0 <4.0.0"
diff --git a/executors/dart/pubspec.yaml b/executors/dart/pubspec.yaml
index 0993b715..2c5aaa08 100644
--- a/executors/dart/pubspec.yaml
+++ b/executors/dart/pubspec.yaml
@@ -2,18 +2,23 @@ name: dart_executor
 publish_to: none
 
 environment:
-  sdk: ^3.10.0
+  sdk: ^3.12.0
 
 dependencies:
   collection: ^1.19.1
-  intl4x: 0.17.0
+  icu4x: ^2.3.1
+  intl4x:
+    git:
+      url: https://github.com/dart-lang/i18n.git
+      path: pkgs/intl4x
+      ref: a3c72590b83f60c3631ece8064d7990840eed187
   node_preamble: ^2.0.2
   pubspec_lock_parse: ^2.2.0
 
 dev_dependencies:
-  lints: ^6.0.0
-  meta: ^1.17.0
-  test: ^1.28.0
+  lints: ^6.1.0
+  meta: ^1.18.3
+  test: ^1.31.2
 
 
 hook:
diff --git a/executors/dart/test/misc_test.dart b/executors/dart/test/misc_test.dart
index 24f1e4f2..143511df 100644
--- a/executors/dart/test/misc_test.dart
+++ b/executors/dart/test/misc_test.dart
@@ -4,13 +4,14 @@ import 'dart:convert';
 import 'package:dart_executor/collator.dart';
 import 'package:dart_executor/datetime_format.dart';
 import 'package:dart_executor/lang_names.dart';
+import 'package:dart_executor/likely_subtags.dart';
 import 'package:dart_executor/numberformat.dart';
 import 'package:intl4x/datetime_format.dart';
 import 'package:meta/meta.dart';
 import 'package:test/test.dart';
 
-/// Run using `dart --enable-experiment=native-assets,record-use test -p chrome` for dart_web
-/// and `dart --enable-experiment=native-assets,record-use test` for dart_native
+/// Run using `dart --enable-experiment=record-use test -p chrome` for dart_web
+/// and `dart --enable-experiment=record-use test` for dart_native
 
 void main() {
   testWithFormatting('Check number format output', () {
@@ -60,6 +61,49 @@ void main() {
     expect(decoded['result'], 'Spanish');
   });
 
+  testWithFormatting('Check likely subtags maximize', () {
+    final inputLine = {
+      'label': 'subtags_max',
+      'locale': 'en',
+      'option': 'maximize',
+    };
+    final outputLine = testLikelySubtags(jsonEncode(inputLine));
+    final decoded = jsonDecode(outputLine) as Map<String, dynamic>;
+    expect(decoded['result'], 'en-Latn-US');
+  });
+
+  testWithFormatting('Check likely subtags minimize', () {
+    final inputLine = {
+      'label': 'subtags_min',
+      'locale': 'en-Latn-US',
+      'option': 'minimize',
+    };
+    final outputLine = testLikelySubtags(jsonEncode(inputLine));
+    final decoded = jsonDecode(outputLine) as Map<String, dynamic>;
+    expect(decoded['result'], 'en');
+  });
+
+  testWithFormatting('Check datetime format with timezone', () {
+    final inputLine = {
+      'label': '00588',
+      'locale': 'en-US',
+      'input_string': '2024-03-17T00:00:00Z',
+      'options': {
+        'timeZone': 'America/Los_Angeles',
+        'dateStyle': 'full',
+        'timeStyle': 'full',
+        'dateTimeFormatType': 'standard',
+        'calendar': 'gregory',
+      },
+      'tz_offset_secs': -25200.0,
+      'original_input': '2024-03-16T17:00-07:00[America/Los_Angeles]',
+    };
+    final outputLine = testDateTimeFmt(jsonEncode(inputLine));
+    final decoded = jsonDecode(outputLine) as Map<String, dynamic>;
+    expect(decoded['result'], contains('Saturday, March 16, 2024'));
+    expect(decoded['result'], contains('Pacific Daylight Time'));
+  });
+
   testWithFormatting('decimal format compact', () {
     final input = {
       'label': '0730',
diff --git a/generateDataAndRun.sh b/generateDataAndRun.sh
index c5d1e42e..98de0bcd 100755
--- a/generateDataAndRun.sh
+++ b/generateDataAndRun.sh
@@ -12,9 +12,9 @@ logrotate -s logrotate.state logrotate.conf
 (while true; do 
   echo "[$(date +%T)] --- VITALS ---"
   # RAM usage
-  echo "Memory: $(free -h | awk 'NR==2{print $3 \" / \" $2}')"
+  echo "Memory: $(free -h | awk 'NR==2{print $3 " / " $2}')"
   # Disk usage for the current workspace
-  echo "Disk: $(df -h . | awk 'NR==2{print $3 \" used / \" $4 \" avail (\" $5 \")\"}')"
+  echo "Disk: $(df -h . | awk 'NR==2{print $3 " used / " $4 " avail (" $5 ")"}')"
   # CPU Load
   echo "CPU Load: $(cut -d' ' -f1-3 /proc/loadavg)"
   echo "------------------------"
@@ -36,7 +36,7 @@ esac
 echo "This machine is: ${machine}"
 
 # Ensure that ICU4C binaries have been downloaded locally
-if [[ ! -d gh-cache ]]
+if [ ! -d gh-cache ] || [ -z "$(ls -A gh-cache 2>/dev/null)" ]
 then
   bash setup_${machine}.sh
 fi
diff --git a/run_config.json b/run_config.json
index 3014f6a3..7e4edd69 100644
--- a/run_config.json
+++ b/run_config.json
@@ -279,7 +279,29 @@
         "number_fmt",
         "lang_names",
         "plural_rules",
-        "list_fmt"
+        "list_fmt",
+        "likely_subtags"
+      ],
+      "per_execution": 10000
+    }
+  },
+  {
+    "prereq": {
+      "name": "nvm 26.3.0, icu78.3",
+      "version": "26.3.0",
+      "command": "nvm install 26.3.0;nvm use 26.3.0 --silent"
+    },
+    "run": {
+      "icu_version": "icu78",
+      "exec": "dart_web",
+      "test_type": [
+        "collation",
+        "datetime_fmt",
+        "number_fmt",
+        "lang_names",
+        "plural_rules",
+        "list_fmt",
+        "likely_subtags"
       ],
       "per_execution": 10000
     }
@@ -299,7 +321,8 @@
         "number_fmt",
         "lang_names",
         "plural_rules",
-        "list_fmt"
+        "list_fmt",
+        "likely_subtags"
       ],
       "per_execution": 10000
     }
@@ -319,7 +342,8 @@
         "number_fmt",
         "lang_names",
         "plural_rules",
-        "list_fmt"
+        "list_fmt",
+        "likely_subtags"
       ],
       "per_execution": 10000
     }
@@ -339,7 +363,8 @@
         "number_fmt",
         "lang_names",
         "plural_rules",
-        "list_fmt"
+        "list_fmt",
+        "likely_subtags"
       ],
       "per_execution": 10000
     }
@@ -359,7 +384,8 @@
         "number_fmt",
         "lang_names",
         "plural_rules",
-        "list_fmt"
+        "list_fmt",
+        "likely_subtags"
       ],
       "per_execution": 10000
     }
@@ -379,7 +405,8 @@
         "number_fmt",
         "lang_names",
         "plural_rules",
-        "list_fmt"
+        "list_fmt",
+        "likely_subtags"
       ],
       "per_execution": 10000
     }
diff --git a/setup_linux.sh b/setup_linux.sh
index 38d5fec6..d366ff00 100755
--- a/setup_linux.sh
+++ b/setup_linux.sh
@@ -3,6 +3,13 @@
 # If there's a problem, exit with error status
 set -e
 
+# install git if not already installed
+if ! command -v git &> /dev/null
+then
+    sudo apt-get update
+    sudo apt-get install -y git
+fi
+
 # install libjson-c-dev if not already installed
 dpkg --list | grep libjson-c-dev || error_code=$?
 if [[ $error_code -ne 0 ]]
diff --git a/testgen/testdata_gen.py b/testgen/testdata_gen.py
index 9f276122..20ada7bd 100644
--- a/testgen/testdata_gen.py
+++ b/testgen/testdata_gen.py
@@ -10,7 +10,11 @@
 from generators.datetime_fmt import DateTimeFmtGenerator
 from generators.localeDisplayNames import LocaleNamesGenerator
 from generators.likely_subtags import LikelySubtagsGenerator
-from generators.message_fmt2 import MessageFmt2Generator
+try:
+    from generators.message_fmt2 import MessageFmt2Generator
+    has_message_fmt2 = True
+except ImportError:
+    has_message_fmt2 = False
 from generators.list_fmt import ListFmtGenerator
 from generators.number_fmt import NumberFmtGenerator
 from generators.plurals import PluralGenerator
@@ -95,8 +99,11 @@ def generate_versioned_data(version_info):
         generator.process_test_data()
 
     if TestType.MESSAGE_FMT2 in args.test_types:
-        generator = MessageFmt2Generator(icu_version, args.run_limit)
-        generator.process_test_data()
+        if not has_message_fmt2:
+            logger.warning("MessageFmt2Generator is not available (missing jsonschema?). Skipping.")
+        else:
+            generator = MessageFmt2Generator(icu_version, args.run_limit)
+            generator.process_test_data()
 
     if TestType.NUMBER_FMT in args.test_types:
         generator = NumberFmtGenerator(icu_version, args.run_limit)
diff --git a/verifier/verifier.py b/verifier/verifier.py
index 41444e85..5daefc10 100644
--- a/verifier/verifier.py
+++ b/verifier/verifier.py
@@ -227,7 +227,7 @@ def setup_verify_plans(self):
     # Verify plans in parallel
     def parallel_verify_data_results(self):
         if not self.options.run_serial:
-            num_processors = mp.cpu_count()
+            num_processors = min(2, mp.cpu_count())
             verify_plans = self.verify_plans
             logger.info('JSON validation: %s processors for %s plans',
                              num_processors, len(verify_plans))