chore: Publish version 0.0.1 of the packages (#103)

packages/serverpod_offline_sync/.gitignore

@@ -0,0 +1,13 @@
+# Files and directories created by pub
+.dart_tool/
+.packages
+
+# Omit committing pubspec.lock for library packages:
+# https://dart.dev/guides/libraries/private-files#pubspeclock
+pubspec.lock
+
+# Conventional directory for build outputs
+build/
+
+# Directory created by dartdoc
+doc/api/

packages/serverpod_offline_sync/CHANGELOG.md

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+../../CHANGELOG.md

packages/serverpod_offline_sync/LICENSE

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+Copyright 2025 The Serverpod authors
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are met:
+
+1. Redistributions of source code must retain the above copyright notice, this
+   list of conditions and the following disclaimer.
+
+2. Redistributions in binary form must reproduce the above copyright notice,
+   this list of conditions and the following disclaimer in the documentation
+   and/or other materials provided with the distribution.
+
+3. Neither the name of the copyright holder nor the names of its contributors
+   may be used to endorse or promote products derived from this software
+   without specific prior written permission.
+
+4. THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+   AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+   IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+   ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
+   LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+   CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+   SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+   INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+   CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+   ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+   POSSIBILITY OF SUCH DAMAGE.

packages/serverpod_offline_sync/README.md

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+../../README.md

packages/serverpod_offline_sync/analysis_options.yaml

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+include: ../../analysis_options.yaml
+
+analyzer:
+  exclude:
+    # - lib/src/generated/**
+
+formatter:
+  trailing_commas: preserve

packages/serverpod_offline_sync/lib/serverpod_offline_sync.dart

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+export 'src/generated/protocol.dart';
+export 'src/hlc/exceptions.dart';
+export 'src/hlc/hlc.dart';

packages/serverpod_offline_sync/lib/src/generated/analysis_options.yaml

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+analyzer:
+  errors:
+    dead_code: ignore
+    duplicate_ignore: ignore
+    unnecessary_type_check: ignore
+
+formatter:
+  trailing_commas: preserve

packages/serverpod_offline_sync/lib/src/generated/hlc/base.dart

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+/* AUTOMATICALLY GENERATED CODE DO NOT MODIFY */
+/*   To generate run: "serverpod generate"    */
+
+// ignore_for_file: implementation_imports
+// ignore_for_file: library_private_types_in_public_api
+// ignore_for_file: non_constant_identifier_names
+// ignore_for_file: public_member_api_docs
+// ignore_for_file: type_literal_in_constant_pattern
+// ignore_for_file: use_super_parameters
+// ignore_for_file: invalid_use_of_internal_member
+
+// ignore_for_file: no_leading_underscores_for_library_prefixes
+import 'package:serverpod_serialization/serverpod_serialization.dart' as _i1;
+
+/// Base class for HLC timestamps.
+///
+/// This class is used to represent the base HLC timestamp, which will be
+/// extended with the node ID (in its canonical or normalized form).
+class BaseHlc implements _i1.SerializableModel {
+  BaseHlc({
+    required this.hlcDatetime,
+    required this.hlcCounter,
+  });
+
+  factory BaseHlc.fromJson(Map<String, dynamic> jsonSerialization) {
+    return BaseHlc(
+      hlcDatetime: _i1.DateTimeJsonExtension.fromJson(
+        jsonSerialization['hlcDatetime'],
+      ),
+      hlcCounter: jsonSerialization['hlcCounter'] as int,
+    );
+  }
+
+  /// The datetime component of the HLC timestamp.
+  DateTime hlcDatetime;
+
+  /// The counter component of the HLC timestamp.
+  int hlcCounter;
+
+  /// Returns a shallow copy of this [BaseHlc]
+  /// with some or all fields replaced by the given arguments.
+  @_i1.useResult
+  BaseHlc copyWith({
+    DateTime? hlcDatetime,
+    int? hlcCounter,
+  }) {
+    return BaseHlc(
+      hlcDatetime: hlcDatetime ?? this.hlcDatetime,
+      hlcCounter: hlcCounter ?? this.hlcCounter,
+    );
+  }
+
+  @override
+  Map<String, dynamic> toJson() {
+    return {
+      '__className__': 'serverpod_offline_sync.BaseHlc',
+      'hlcDatetime': hlcDatetime.toJson(),
+      'hlcCounter': hlcCounter,
+    };
+  }
+
+  @override
+  String toString() {
+    return _i1.SerializationManager.encode(this);
+  }
+}

packages/serverpod_offline_sync/lib/src/generated/protocol.dart

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+/* AUTOMATICALLY GENERATED CODE DO NOT MODIFY */
+/*   To generate run: "serverpod generate"    */
+
+// ignore_for_file: implementation_imports
+// ignore_for_file: library_private_types_in_public_api
+// ignore_for_file: non_constant_identifier_names
+// ignore_for_file: public_member_api_docs
+// ignore_for_file: type_literal_in_constant_pattern
+// ignore_for_file: use_super_parameters
+// ignore_for_file: invalid_use_of_internal_member
+
+// ignore_for_file: no_leading_underscores_for_library_prefixes
+import 'package:serverpod_serialization/serverpod_serialization.dart' as _i1;
+import 'hlc/base.dart' as _i2;
+export 'hlc/base.dart';
+
+class Protocol extends _i1.SerializationManager {
+  Protocol._();
+
+  factory Protocol() => _instance;
+
+  static final Protocol _instance = Protocol._();
+
+  final Set<_i1.SerializationManager> _hostProtocols = {};
+
+  void registerHostProtocol(
+    String projectName,
+    _i1.SerializationManager protocol,
+  ) {
+    _hostProtocols.add(protocol);
+  }
+
+  static String? getClassNameFromObjectJson(dynamic data) {
+    if (data is! Map) return null;
+    final className = data['__className__'] as String?;
+    if (className == null) return null;
+    if (!className.startsWith('serverpod_offline_sync.')) return className;
+    return className.substring(23);
+  }
+
+  @override
+  T deserialize<T>(
+    dynamic data, [
+    Type? t,
+  ]) {
+    t ??= T;
+
+    final dataClassName = getClassNameFromObjectJson(data);
+    if (dataClassName != null && dataClassName != getClassNameForType(t)) {
+      try {
+        return deserializeByClassName({
+          'className': dataClassName,
+          'data': data,
+        });
+      } on FormatException catch (_) {
+        // If the className is not recognized (e.g., older client receiving
+        // data with a new subtype), fall back to deserializing without the
+        // className, using the expected type T.
+      }
+    }
+
+    if (t == _i2.BaseHlc) {
+      return _i2.BaseHlc.fromJson(data) as T;
+    }
+    if (t == _i1.getType<_i2.BaseHlc?>()) {
+      return (data != null ? _i2.BaseHlc.fromJson(data) : null) as T;
+    }
+    return super.deserialize<T>(data, t);
+  }
+
+  static String? getClassNameForType(Type type) {
+    return switch (type) {
+      _i2.BaseHlc => 'BaseHlc',
+      _ => null,
+    };
+  }
+
+  @override
+  String? getClassNameForObject(Object? data) {
+    String? className = super.getClassNameForObject(data);
+    if (className != null) return className;
+
+    if (data is Map<String, dynamic> && data['__className__'] is String) {
+      return (data['__className__'] as String).replaceFirst(
+        'serverpod_offline_sync.',
+        '',
+      );
+    }
+
+    switch (data) {
+      case _i2.BaseHlc():
+        return 'BaseHlc';
+    }
+    return null;
+  }
+
+  @override
+  dynamic deserializeByClassName(Map<String, dynamic> data) {
+    var dataClassName = data['className'];
+    if (dataClassName is! String) {
+      return super.deserializeByClassName(data);
+    }
+    if (dataClassName == 'BaseHlc') {
+      return deserialize<_i2.BaseHlc>(data['data']);
+    }
+    return super.deserializeByClassName(data);
+  }
+
+  @override
+  Object? dynamicFieldToJson(
+    Object? object, {
+    bool forProtocol = false,
+  }) {
+    if ((object is List || object is Set || object is Map) ||
+        getClassNameForObject(object) != null) {
+      return super.dynamicFieldToJson(object, forProtocol: forProtocol);
+    }
+    for (final protocol in _hostProtocols) {
+      final className = protocol.getClassNameForObject(object);
+      if (className == null) continue;
+      final host = protocol.getModuleName();
+      final wrapped = {
+        'className': className.contains('.') ? className : '$host.$className',
+        'data': object,
+      };
+      return forProtocol
+          ? _i1.SerializationManager.toEncodableForProtocol(wrapped)
+          : _i1.SerializationManager.toEncodable(wrapped);
+    }
+    return super.dynamicFieldToJson(object, forProtocol: forProtocol);
+  }
+
+  @override
+  dynamic deserializeDynamicFieldValue(Object? value) {
+    if (value == null) return null;
+    if (value is! Map<String, dynamic> || value['className'] is! String) {
+      throw FormatException(
+        'Dynamic fields are encoded as a Map with className and data, but got '
+        '${value.runtimeType} instead.',
+      );
+    }
+    final className = value['className'] as String;
+    for (final protocol in _hostProtocols) {
+      final host = protocol.getModuleName();
+      final hostPrefix = '$host.';
+      if (className.startsWith(hostPrefix)) {
+        final strippedClassName = className.substring(hostPrefix.length);
+        if (strippedClassName.contains('.')) {
+          throw FormatException(
+            'Dynamic field className must not use multiple prefixes: $className',
+          );
+        }
+        final hostData = Map<String, dynamic>.from(value);
+        hostData['className'] = strippedClassName;
+        return protocol.deserializeByClassName(hostData);
+      }
+    }
+    if (className.contains('.')) {
+      for (final protocol in _hostProtocols) {
+        try {
+          return protocol.deserializeByClassName(value);
+        } on FormatException catch (_) {}
+      }
+    }
+    return deserializeByClassName(value);
+  }
+
+  @override
+  String getModuleName() => 'serverpod_offline_sync';
+
+  /// Maps any `Record`s known to this [Protocol] to their JSON representation
+  ///
+  /// Throws in case the record type is not known.
+  ///
+  /// This method will return `null` (only) for `null` inputs.
+  Map<String, dynamic>? mapRecordToJson(Record? record) {
+    if (record == null) {
+      return null;
+    }
+    throw Exception('Unsupported record type ${record.runtimeType}');
+  }
+}

packages/serverpod_offline_sync/lib/src/hlc/base.spy.yaml

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+### Base class for HLC timestamps.
+###
+### This class is used to represent the base HLC timestamp, which will be
+### extended with the node ID (in its canonical or normalized form).
+class: BaseHlc
+fields:
+  ### The datetime component of the HLC timestamp.
+  hlcDatetime: DateTime
+
+  ### The counter component of the HLC timestamp.
+  hlcCounter: int

packages/serverpod_offline_sync/lib/src/hlc/exceptions.dart

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+import 'package:serverpod_serialization/serverpod_serialization.dart';
+
+/// Exception thrown when the clock drift exceeds the maximum allowed.
+class ClockDriftException implements Exception {
+  /// Creates a new instance of [ClockDriftException].
+  ClockDriftException(DateTime dateTime, DateTime wallTime, this.maxDrift)
+    : drift = dateTime.difference(wallTime);
+
+  /// The duration of the clock drift.
+  final Duration drift;
+
+  /// The maximum allowed clock drift.
+  final Duration maxDrift;
+
+  @override
+  String toString() => 'Clock drift of $drift ms exceeds maximum ($maxDrift)';
+}
+
+/// Exception thrown when the timestamp counter overflows.
+class OverflowException implements Exception {
+  /// Creates a new instance of [OverflowException].
+  OverflowException(this.counter);
+
+  /// The counter that overflowed.
+  final int counter;
+
+  @override
+  String toString() => 'Timestamp counter overflow: $counter';
+}
+
+/// Exception thrown when a duplicate node is detected.
+class DuplicateNodeException implements Exception {
+  /// Creates a new instance of [DuplicateNodeException].
+  DuplicateNodeException(this.nodeId);
+
+  /// The node ID that is duplicated.
+  final UuidValue nodeId;
+
+  @override
+  String toString() => 'Duplicate node: $nodeId';
+}

packages/serverpod_offline_sync/lib/src/hlc/hlc.dart

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+// This file includes code from the project: https://github.com/cachapa/crdt
+// Licensed under Apache License 2.0: https://www.apache.org/licenses/LICENSE-2.0
+// Copyright Daniel Cachapa.
+//
+// Modifications copyright 2026 Marcelo Soares
+// Licensed under MIT License: https://opensource.org/licenses/MIT
+
+import 'package:clock/clock.dart';
+import 'package:serverpod_serialization/serverpod_serialization.dart';
+
+import '../../src/generated/hlc/base.dart';
+import 'exceptions.dart';
+
+/// A Hybrid Logical Clock implementation that supports both ISO 8601 and Unix
+/// timestamp formats. The datetime component has millisecond precision and is
+/// always stored in UTC.
+///
+/// Although the original HLC paper uses microsecond precision, since it was
+/// proved that the counter typically stays in single digits, millisecond
+/// precision can be considered enough for the vast majority of applications.
+///
+/// The advantage of using milliseconds is that the timestamp can be generated
+/// on any database (inside SQLite3 for example) and will occupy less space in
+/// the database.
+///
+/// Inspiration: https://cse.buffalo.edu/tech-reports/2014-04.pdf
+@immutable
+class Hlc implements Comparable<Hlc> {
+  /// Creates a new instance of [Hlc].
+  ///
+  /// Precision of the [datetime] is milliseconds.
+  factory Hlc(DateTime datetime, int counter, UuidValue nodeId) =>
+      Hlc._(datetime.toUtcMillisecond(), counter, nodeId);
+
+  /// Parse an HLC string in the format `<ISO8601_date>-<counter>-<node_id>`
+  /// or `<unix_timestamp>-<counter>-<node_id>`.
+  ///
+  /// For backward compatibility, the node segment may use a legacy
+  /// `uuid:worker_id` form; the worker suffix is ignored.
+  factory Hlc.parse(String timestamp) {
+    final indexOfColon = timestamp.indexOf(':');
+    final indexOfStart = indexOfColon > 0 && indexOfColon < 20 ? indexOfColon : 0;
+
+    final counterDash = timestamp.indexOf('-', indexOfStart);
+    final timestampPart = timestamp.substring(0, counterDash);
+
+    final nodeIdDash = timestamp.indexOf('-', counterDash + 1);
+    final counterPart = timestamp.substring(counterDash + 1, nodeIdDash);
+
+    final unixTimestamp = int.tryParse(timestampPart);
+    final datetime = unixTimestamp != null
+        ? DateTime.fromMillisecondsSinceEpoch(unixTimestamp, isUtc: true)
+        : DateTime.tryParse(timestampPart);
+
+    if (datetime == null) {
+      throw FormatException('Invalid HLC string: $timestamp');
+    }
+
+    final counter = int.parse(counterPart, radix: 16);
+    final nodeIdPart = timestamp.substring(nodeIdDash + 1);
+    return Hlc(datetime, counter, parseNodeSegment(nodeIdPart));
+  }
+
+  /// Convenience method to decode the HLC from a JSON map.
+  factory Hlc.fromJson(Map<String, dynamic> json) => Hlc(
+    DateTime.parse(json['datetime'] as String),
+    int.parse(json['counter'] as String, radix: 16),
+    UuidValue.withValidation(json['node'] as String),
+  );
+
+  const Hlc._(this.datetime, this.counter, this.nodeId)
+    : assert(counter <= _maxCounter);
+
+  /// Instantiates an Hlc at the beginning of time and space: January 1, 1970.
+  factory Hlc.zero(UuidValue nodeId) => Hlc(DateTime.utc(1970), 0, nodeId);
+
+  /// Instantiates an Hlc using the wall clock.
+  factory Hlc.now(UuidValue nodeId) => Hlc(DateTime.now(), 0, nodeId);
+
+  /// Parses the node segment of an HLC string: a UUID, or legacy `uuid:workerId`.
+  static UuidValue parseNodeSegment(String segment) {
+    final parts = segment.split(':');
+    if (parts.length == 2 && int.tryParse(parts[1]) != null) {
+      return UuidValue.withValidation(parts[0]);
+    }
+    return UuidValue.withValidation(segment);
+  }
+
+  /// The date and time of the HLC.
+  final DateTime datetime;
+
+  /// The counter of the HLC.
+  final int counter;
+
+  /// The logical node ID for this HLC.
+  final UuidValue nodeId;
+
+  /// The Unix timestamp of the HLC.
+  int get unixTimestamp => datetime.millisecondsSinceEpoch;
+
+  static const _maxDrift = Duration(minutes: 1);
+  static const _maxCounter = 0xFFFF;
+
+  /// Increments the current timestamp for transmission to another system.
+  Hlc increment() {
+    final localWallTime = clock.now().toUtc();
+    final datetimeNew = localWallTime.isAfter(datetime) ? localWallTime : datetime;
+    final counterNew = datetimeNew == datetime ? counter + 1 : 0;
+
+    if (datetimeNew.difference(localWallTime) > const Duration(minutes: 1)) {
+      throw ClockDriftException(datetimeNew, localWallTime, _maxDrift);
+    }
+    if (counterNew > _maxCounter) {
+      throw OverflowException(counterNew);
+    }
+
+    return Hlc(datetimeNew, counterNew, nodeId);
+  }
+
+  /// Compares and validates a timestamp from a remote system with the local
+  /// timestamp to preserve monotonicity.
+  Hlc merge(Hlc remote) {
+    if (remote.datetime.isBefore(datetime) ||
+        (remote.datetime.isAtSameMomentAs(datetime) && remote.counter <= counter)) {
+      return this;
+    }
+
+    if (nodeId == remote.nodeId) {
+      throw DuplicateNodeException(nodeId);
+    }
+
+    final localWallTime = clock.now().toUtc();
+    if (remote.datetime.difference(localWallTime) > _maxDrift) {
+      throw ClockDriftException(remote.datetime, localWallTime, _maxDrift);
+    }
+
+    return remote.copyWith(nodeId: nodeId);
+  }
+
+  /// Create a copy of this object replacing the optional properties.
+  Hlc copyWith({DateTime? datetime, int? counter, UuidValue? nodeId}) => Hlc(
+    datetime ?? this.datetime,
+    counter ?? this.counter,
+    nodeId ?? this.nodeId,
+  );
+
+  /// Returns the maximum HLC between the two given HLCs.
+  Hlc maxBetween(Hlc? other) => other == null || this > other ? this : other;
+
+  @override
+  String toString() =>
+      '${datetime.toIso8601String()}-'
+      '${counter.toRadixString(16).toUpperCase().padLeft(4, '0')}-'
+      '$nodeId';
+
+  /// Convenience method for easy json encoding.
+  Map<String, dynamic> toJson() => {
+    'datetime': datetime.toIso8601String(),
+    'counter': counter.toRadixString(16).toUpperCase().padLeft(4, '0'),
+    'node': nodeId.toString(),
+  };
+
+  @override
+  int get hashCode => toString().hashCode;
+
+  @override
+  bool operator ==(Object other) => other is Hlc && compareTo(other) == 0;
+
+  /// Whether this [Hlc] is causally before the [other].
+  bool operator <(Object other) => other is Hlc && compareTo(other) < 0;
+
+  /// Whether this [Hlc] is causally before or equal to the [other].
+  bool operator <=(Object other) => this < other || this == other;
+
+  /// Whether this [Hlc] is causally after the [other].
+  bool operator >(Object other) => other is Hlc && compareTo(other) > 0;
+
+  /// Whether this [Hlc] is causally after or equal to the [other].
+  bool operator >=(Object other) => this > other || this == other;
+
+  @override
+  int compareTo(Hlc other) => datetime.isAtSameMomentAs(other.datetime)
+      ? counter == other.counter
+            ? nodeId.uuid.compareTo(other.nodeId.uuid)
+            : counter - other.counter
+      : datetime.compareTo(other.datetime);
+}
+
+extension on DateTime {
+  DateTime toUtcMillisecond() =>
+      DateTime.fromMillisecondsSinceEpoch(millisecondsSinceEpoch, isUtc: true);
+}
+
+/// Extensions for [BaseHlc] to convert it to an [Hlc].
+extension BaseHlcToHlc on BaseHlc {
+  /// Converts the [BaseHlc] to an [Hlc] with the given [nodeId].
+  Hlc toHlcForNode(UuidValue nodeId) => Hlc(hlcDatetime, hlcCounter, nodeId);
+}
+
+/// Extensions for an [Iterable] of [Hlc].
+extension HlcMax on Iterable<Hlc> {
+  /// The greatest HLC represented by the HLCs in this iterable.
+  Hlc get max => reduce((a, b) => a > b ? a : b);
+}

packages/serverpod_offline_sync/pubspec.yaml

@@ -0,0 +1,19 @@
+name: serverpod_offline_sync
+version: 0.0.1
+description: Shared package for the Serverpod Offline Sync project.
+homepage: https://github.com/marcelomendoncasoares/serverpod_offline_sync
+
+environment:
+  sdk: '^3.10.3'
+
+resolution: workspace
+
+dependencies:
+  clock: ^1.1.2
+  serverpod_database: 4.0.0-beta.0
+  serverpod_serialization: 4.0.0-beta.0
+  uuid: ^4.5.3
+
+dev_dependencies:
+  lints: '>=3.0.0 <7.0.0'
+  test: ^1.25.5

packages/serverpod_offline_sync/test/hlc/hlc_comparison_test.dart

@@ -0,0 +1,129 @@
+import 'package:serverpod_offline_sync/serverpod_offline_sync.dart';
+import 'package:test/test.dart';
+import 'package:uuid/uuid.dart';
+
+final _dateTime = DateTime.parse('2001-09-09T01:46:40.000Z');
+final _nodeId = const Uuid().v4obj();
+
+void main() {
+  group('Given two Hlcs with same dateTime, counter and nodeId when comparing ', () {
+    final hlc1 = Hlc(_dateTime, 17, _nodeId);
+    final hlc2 = Hlc(_dateTime, 17, _nodeId);
+
+    test('then they are equal.', () {
+      expect(hlc1, hlc2);
+      expect(hlc1 == hlc2, isTrue);
+      expect(hlc1, equals(hlc2));
+    });
+
+    test('then compareTo returns 0.', () {
+      expect(hlc1.compareTo(hlc2), 0);
+    });
+
+    test('then <= is true.', () {
+      expect(hlc1 <= hlc2, isTrue);
+      expect(hlc1, lessThanOrEqualTo(hlc2));
+    });
+
+    test('then >= is true.', () {
+      expect(hlc1 >= hlc2, isTrue);
+      expect(hlc1, greaterThanOrEqualTo(hlc2));
+    });
+  });
+
+  group(
+    'Given two Hlcs with same dateTime and counter and different nodeId when comparing ',
+    () {
+      final node2 = const Uuid().v4obj();
+
+      final hlc1 = Hlc(_dateTime, 17, _nodeId);
+      final hlc2 = Hlc(_dateTime, 17, node2);
+
+      test('then they are not equal.', () {
+        expect(hlc1, isNot(hlc2));
+      });
+
+      test('then compareTo follows lexicographic node uuid order.', () {
+        expect(
+          hlc1.compareTo(hlc2),
+          hlc1.nodeId.uuid.compareTo(hlc2.nodeId.uuid),
+        );
+      });
+
+      test('then one is greater or less by uuid order.', () {
+        if (_nodeId.uuid.compareTo(node2.uuid) > 0) {
+          expect(hlc1 > hlc2, isTrue);
+        } else {
+          expect(hlc1 < hlc2, isTrue);
+        }
+      });
+    },
+  );
+
+  group('Given two Hlcs with same dateTime and different counter when comparing ', () {
+    final hlc1 = Hlc(_dateTime, 17, _nodeId);
+    final hlc2 = Hlc(_dateTime, 18, _nodeId);
+
+    test('then they are not equal.', () {
+      expect(hlc1, isNot(hlc2));
+    });
+
+    test('then compareTo returns -1.', () {
+      expect(hlc1.compareTo(hlc2), -1);
+    });
+
+    test('then < is true.', () {
+      expect(hlc1 < hlc2, isTrue);
+      expect(hlc1, lessThan(hlc2));
+    });
+
+    test('then <= is true.', () {
+      expect(hlc1 <= hlc2, isTrue);
+      expect(hlc1, lessThanOrEqualTo(hlc2));
+    });
+
+    test('then > is false.', () {
+      expect(hlc1 > hlc2, isFalse);
+    });
+
+    test('then >= is false.', () {
+      expect(hlc1 >= hlc2, isFalse);
+      expect(hlc1, isNot(greaterThanOrEqualTo(hlc2)));
+    });
+  });
+
+  group(
+    'Given two Hlcs with different dateTime when comparing ',
+    () {
+      final hlc1 = Hlc(_dateTime, 0, _nodeId);
+      final hlc2 = Hlc(_dateTime.add(const Duration(milliseconds: 1)), 17, _nodeId);
+
+      test('then they are not equal.', () {
+        expect(hlc1, isNot(hlc2));
+      });
+
+      test('then compareTo returns -1.', () {
+        expect(hlc1.compareTo(hlc2), -1);
+      });
+
+      test('then < is true.', () {
+        expect(hlc1 < hlc2, isTrue);
+        expect(hlc1, lessThan(hlc2));
+      });
+
+      test('then <= is true.', () {
+        expect(hlc1 <= hlc2, isTrue);
+        expect(hlc1, lessThanOrEqualTo(hlc2));
+      });
+
+      test('then > is false.', () {
+        expect(hlc1 > hlc2, isFalse);
+      });
+
+      test('then >= is false.', () {
+        expect(hlc1 >= hlc2, isFalse);
+        expect(hlc1, isNot(greaterThanOrEqualTo(hlc2)));
+      });
+    },
+  );
+}

packages/serverpod_offline_sync/test/hlc/hlc_copy_with_test.dart

@@ -0,0 +1,32 @@
+import 'package:serverpod_offline_sync/serverpod_offline_sync.dart';
+import 'package:test/test.dart';
+import 'package:uuid/uuid.dart';
+
+final _dateTime = DateTime.parse('2001-09-09T01:46:40.000Z');
+final _nodeId = const Uuid().v4obj();
+
+void main() {
+  group('Given an HLC', () {
+    final hlc = Hlc(_dateTime, 17, _nodeId);
+
+    test('when calling copyWith with new dateTime then result has new dateTime.', () {
+      final newDateTime = _dateTime.add(const Duration(minutes: 1));
+      final newHlc = hlc.copyWith(datetime: newDateTime);
+
+      expect(newHlc.datetime, newDateTime);
+    });
+
+    test('when calling copyWith with new counter then result has new counter.', () {
+      final newHlc = hlc.copyWith(counter: 18);
+
+      expect(newHlc.counter, 18);
+    });
+
+    test('when calling copyWith with new nodeId then result has new nodeId.', () {
+      final newNodeId = const Uuid().v4obj();
+      final newHlc = hlc.copyWith(nodeId: newNodeId);
+
+      expect(newHlc.nodeId, newNodeId);
+    });
+  });
+}

packages/serverpod_offline_sync/test/hlc/hlc_increment_test.dart

@@ -0,0 +1,84 @@
+import 'package:clock/clock.dart';
+import 'package:serverpod_offline_sync/serverpod_offline_sync.dart';
+import 'package:test/test.dart';
+import 'package:uuid/uuid.dart';
+
+final _dateTime = DateTime.parse('2001-09-09T01:46:40.000Z');
+final _nodeId = const Uuid().v4obj();
+
+void main() {
+  group('Given an HLC with lower canonical time than wall time', () {
+    final hlc = Hlc(_dateTime, 17, _nodeId);
+    final wallTime = _dateTime.advance();
+
+    test('when incrementing then dateTime becomes wall time and counter resets.', () {
+      withClock(Clock.fixed(wallTime), () {
+        final sendHlc = hlc.increment();
+
+        expect(sendHlc, isNot(hlc));
+        expect(sendHlc.datetime, wallTime);
+        expect(sendHlc.counter, 0);
+        expect(sendHlc.nodeId, hlc.nodeId);
+      });
+    });
+  });
+
+  group('Given an HLC with equal canonical time and wall time', () {
+    final hlc = Hlc(_dateTime, 17, _nodeId);
+    final wallTime = _dateTime;
+
+    test('when incrementing then counter increments and dateTime is unchanged.', () {
+      withClock(Clock.fixed(wallTime), () {
+        final sendHlc = hlc.increment();
+
+        expect(sendHlc, isNot(hlc));
+        expect(sendHlc.datetime, hlc.datetime);
+        expect(sendHlc.counter, 18);
+        expect(sendHlc.nodeId, hlc.nodeId);
+      });
+    });
+  });
+
+  group('Given an HLC with higher canonical time than wall time', () {
+    final hlc = Hlc(_dateTime, 17, _nodeId);
+    final wallTime = _dateTime.retreat();
+
+    test('when incrementing then counter increments and dateTime is unchanged.', () {
+      withClock(Clock.fixed(wallTime), () {
+        final sendHlc = hlc.increment();
+
+        expect(sendHlc, isNot(hlc));
+        expect(sendHlc.datetime, hlc.datetime);
+        expect(sendHlc.counter, 18);
+        expect(sendHlc.nodeId, hlc.nodeId);
+      });
+    });
+  });
+
+  group('Given an HLC with canonical time more than one minute ahead of wall time', () {
+    final hlc = Hlc(_dateTime.add(const Duration(minutes: 1, seconds: 5)), 0, _nodeId);
+    final wallTime = _dateTime;
+
+    test('when incrementing then ClockDriftException is thrown.', () {
+      withClock(Clock.fixed(wallTime), () {
+        expect(hlc.increment, throwsA(isA<ClockDriftException>()));
+      });
+    });
+  });
+
+  group('Given an HLC with counter at maximum and canonical time at wall time', () {
+    final hlc = Hlc(_dateTime, 0xFFFF, _nodeId);
+    final wallTime = _dateTime;
+
+    test('when incrementing at same time then OverflowException is thrown.', () {
+      withClock(Clock.fixed(wallTime), () {
+        expect(hlc.increment, throwsA(isA<OverflowException>()));
+      });
+    });
+  });
+}
+
+extension on DateTime {
+  DateTime advance() => add(const Duration(milliseconds: 1));
+  DateTime retreat() => subtract(const Duration(milliseconds: 1));
+}

packages/serverpod_offline_sync/test/hlc/hlc_merge_test.dart

@@ -0,0 +1,113 @@
+import 'package:clock/clock.dart';
+import 'package:serverpod_offline_sync/serverpod_offline_sync.dart';
+import 'package:test/test.dart';
+import 'package:uuid/uuid.dart';
+
+final _dateTime = DateTime.now().toUtc();
+final _nodeId = const Uuid().v4obj();
+final _nodeIdAfter = const Uuid().v4obj();
+
+void main() {
+  group('Given local canonical Hlc and remote with higher time', () {
+    final canonical = Hlc(_dateTime, 17, _nodeId);
+    final remote = Hlc(_dateTime.advance(), 2, _nodeIdAfter);
+
+    test('when merging then result has remote time and counter with local nodeId.', () {
+      final hlc = canonical.merge(remote);
+
+      expect(hlc, Hlc(remote.datetime, remote.counter, canonical.nodeId));
+    });
+  });
+
+  group('Given local canonical Hlc and remote with same time but higher counter', () {
+    final canonical = Hlc(_dateTime, 17, _nodeId);
+    final remote = Hlc(_dateTime, 18, _nodeIdAfter);
+
+    test('when merging then result has remote counter with local nodeId.', () {
+      final hlc = canonical.merge(remote);
+
+      expect(hlc, Hlc(canonical.datetime, remote.counter, canonical.nodeId));
+    });
+  });
+
+  group('Given local canonical Hlc and remote with same time and counter', () {
+    final canonical = Hlc(_dateTime, 17, _nodeId);
+    final remote = Hlc(_dateTime, 17, _nodeIdAfter);
+
+    test('when merging then local is returned.', () {
+      final hlc = canonical.merge(remote);
+
+      expect(hlc, equals(canonical));
+    });
+  });
+
+  group('Given local canonical Hlc and remote with lower time', () {
+    final canonical = Hlc(_dateTime, 17, _nodeId);
+    final remote = Hlc(_dateTime.retreat(), 17, _nodeIdAfter);
+
+    test('when merging then local is returned.', () {
+      final hlc = canonical.merge(remote);
+
+      expect(hlc, equals(canonical));
+    });
+  });
+
+  group('Given local canonical Hlc and remote with same nodeId and same time', () {
+    final canonical = Hlc(_dateTime, 17, _nodeId);
+    final remote = Hlc(_dateTime, 17, _nodeId);
+
+    test('when merging then node id is not checked and local is returned.', () {
+      expect(canonical.merge(remote), canonical);
+    });
+  });
+
+  group('Given local canonical Hlc and remote with same nodeId and lower time', () {
+    final canonical = Hlc(_dateTime, 17, _nodeId);
+    final remote = Hlc(_dateTime.retreat(), 17, _nodeId);
+
+    test('when merging then node id is not checked and local is returned.', () {
+      expect(canonical.merge(remote), canonical);
+    });
+  });
+
+  group('Given local canonical Hlc and remote with same nodeId and higher time', () {
+    final canonical = Hlc(_dateTime, 17, _nodeId);
+    final remote = Hlc(_dateTime.advance(), 0, _nodeId);
+
+    test('when merging then DuplicateNodeException is thrown.', () {
+      expect(
+        () => canonical.merge(remote),
+        throwsA(isA<DuplicateNodeException>()),
+      );
+    });
+  });
+
+  group(
+    'Given local canonical Hlc and remote with time more than one minute ahead of wall',
+    () {
+      final canonical = Hlc(_dateTime, 17, _nodeId);
+      final remote = Hlc(
+        _dateTime.advance(const Duration(minutes: 2)),
+        17,
+        _nodeIdAfter,
+      );
+
+      test('when merging then ClockDriftException is thrown.', () {
+        withClock(Clock.fixed(_dateTime.advance()), () {
+          expect(
+            () => canonical.merge(remote),
+            throwsA(isA<ClockDriftException>()),
+          );
+        });
+      });
+    },
+  );
+}
+
+extension on DateTime {
+  DateTime advance([Duration duration = const Duration(milliseconds: 1)]) =>
+      add(duration);
+
+  DateTime retreat([Duration duration = const Duration(milliseconds: 1)]) =>
+      subtract(duration);
+}

packages/serverpod_offline_sync/test/hlc/hlc_serialization_test.dart

@@ -0,0 +1,74 @@
+import 'package:serverpod_offline_sync/serverpod_offline_sync.dart';
+import 'package:test/test.dart';
+import 'package:uuid/uuid.dart';
+
+const _isoTime = '2001-09-09T01:46:40.000Z';
+final _dateTime = DateTime.parse(_isoTime);
+final _nodeId = const Uuid().v4obj();
+
+void main() {
+  test('Given an HLC built with dateTime, counter and nodeId '
+      'when reading properties '
+      'then dateTime, counter and nodeId match.', () {
+    final hlc = Hlc(_dateTime, 0x17, _nodeId);
+
+    expect(hlc.datetime, _dateTime);
+    expect(hlc.counter, 0x17);
+    expect(hlc.nodeId, _nodeId);
+  });
+
+  test('Given Hlc.zero '
+      'when building for a nodeId '
+      'then it equals epoch with zero counter.', () {
+    final zero = Hlc.zero(_nodeId);
+
+    expect(zero.unixTimestamp, 0);
+    expect(zero.counter, 0);
+    expect(zero.nodeId, _nodeId);
+  });
+
+  test('Given an ISO HLC string '
+      'when parsing '
+      'then it returns the equivalent Hlc.', () {
+    final hlc = Hlc(_dateTime, 0x17, _nodeId);
+
+    expect(Hlc.parse('${_dateTime.toIso8601String()}-0017-$_nodeId'), hlc);
+  });
+
+  test('Given a Unix timestamp HLC string '
+      'when parsing '
+      'then it returns the equivalent Hlc.', () {
+    final hlc = Hlc(_dateTime, 0x17, _nodeId);
+
+    expect(Hlc.parse('${_dateTime.millisecondsSinceEpoch}-0017-$_nodeId'), hlc);
+  });
+
+  test('Given legacy string with :worker suffix '
+      'when parsing '
+      'then node id is the uuid only.', () {
+    final hlc = Hlc.parse('$_isoTime-0017-$_nodeId:7');
+    expect(hlc.nodeId, _nodeId);
+    expect(hlc.counter, 0x17);
+    expect(hlc.datetime, _dateTime);
+  });
+
+  test('Given a parsed Hlc '
+      'when calling toString '
+      'then it returns the ISO HLC string.', () {
+    final hlc = Hlc.parse('$_isoTime-0017-$_nodeId');
+
+    expect(hlc.toString(), '$_isoTime-0017-$_nodeId');
+  });
+
+  test('Given an HLC '
+      'when converting to JSON '
+      'then it returns the equivalent string.', () {
+    final hlc = Hlc(_dateTime, 0x17, _nodeId);
+
+    expect(hlc.toJson(), {
+      'datetime': _dateTime.toIso8601String(),
+      'counter': '0017',
+      'node': _nodeId.toString(),
+    });
+  });
+}

packages/serverpod_offline_sync_client/CHANGELOG.md

@@ -0,0 +1 @@
+../../CHANGELOG.md

packages/serverpod_offline_sync_client/README.md

@@ -1,3 +0,0 @@
-# serverpod_offline_sync_client
-
-Client package for the Serverpod Offline Sync project.

packages/serverpod_offline_sync_client/README.md

@@ -0,0 +1 @@
+../../README.md