Revisions

Examples/StandaloneWebServer/Program.cs

@@ -14,15 +14,12 @@ internal class Program
 
     private static async Task Main(string[] args)
     {
-        var epPort = ushort.Parse(
-            Environment.GetEnvironmentVariable("ESIUR_PORT")
-            ?? throw new InvalidOperationException("Set ESIUR_PORT before starting the example."));
         var wh = new Warehouse();
 
         // Create a store to keep objects.
         var system = await wh.Put("sys", new MemoryStore());
         // Create a distibuted server
-        var esiurServer = await wh.Put("sys/server", new EpServer() { Port = epPort });
+        var esiurServer = await wh.Put("sys/server", new EpServer());
         // Add your object to the store
         var service = await wh.Put("sys/demo", new Demo());
 

Libraries/Esiur/Core/ExceptionCode.cs

@@ -51,5 +51,6 @@ public enum ExceptionCode : ushort
     ParserLimitExceeded,
     AttachmentLimitExceeded,
     AlreadyAttached,
-    ConnectionLimitExceeded
+    ConnectionLimitExceeded,
+    CursorExpired
 }

Libraries/Esiur/Data/Codec.cs

@@ -228,13 +228,13 @@ public static class Codec
                 asyncReply.Then(value =>
                 {
                     rt.Trigger(new ParseResult<object>(value, (uint)tdu.TotalLength));
-                });
+                }).Error(rt.TriggerError);
             }
             else
             {
                 rt.Trigger(new ParseResult<object>(result, (uint)tdu.TotalLength));
             }
-        });
+        }).Error(rt.TriggerError);
 
         return rt;
 

Libraries/Esiur/Data/IDynamicResource.cs

@@ -1,5 +1,6 @@
 using Esiur.Core;
 using Esiur.Data.Types;
+using Esiur.Protocol;
 using System;
 using System.Collections.Generic;
 using System.Text;
@@ -17,4 +18,28 @@ namespace Esiur.Data
 
         public TypeDef ResourceDefinition { get; }
     }
+
+    /// <summary>
+    /// Optional server-side invocation hook for local resources whose type
+    /// definition is assembled at runtime. Remote <see cref="EpResource"/>
+    /// proxies remain unchanged; this hook gives their local counterpart the
+    /// same dynamic function semantics.
+    /// </summary>
+    public interface IDynamicResourceFunctionHandler
+    {
+        public AsyncReply InvokeResourceFunctionAsync(
+            byte index,
+            object arguments,
+            InvocationContext context);
+    }
+
+    public delegate void DynamicResourceEventHandler(byte index, object value);
+
+    /// <summary>
+    /// Optional event bridge for a local runtime-defined resource.
+    /// </summary>
+    public interface IDynamicResourceEventSource
+    {
+        public event DynamicResourceEventHandler ResourceEventOccurred;
+    }
 }

Libraries/Esiur/Data/RuntimeCaster.cs

@@ -5,6 +5,7 @@ using System.Collections.Concurrent;
 using System.Collections.Generic;
 using System.Globalization;
 using System.Linq.Expressions;
+using System.Reflection;
 using System.Runtime.CompilerServices;
 
 namespace Esiur.Data;
@@ -55,6 +56,9 @@ public static class RuntimeCaster
         Func<object?, RuntimeCastOptions, object?>> _elemConvCache =
         new ConcurrentDictionary<(Type, Type), Func<object?, RuntimeCastOptions, object?>>();
 
+    private static readonly ConcurrentDictionary<Type, PropertyInfo[]> _recordPropertyCache =
+        new ConcurrentDictionary<Type, PropertyInfo[]>();
+
     // --------- Zero-allocation convenience overloads ---------
     public static object? Cast(object? value, Type toType)
         => Cast(value, toType, RuntimeCastOptions.Default);
@@ -149,6 +153,13 @@ public static class RuntimeCaster
         var toUnderlying = Nullable.GetUnderlyingType(toType) ?? toType;
         var fromUnderlying = Nullable.GetUnderlyingType(fromType) ?? fromType;
 
+        // A peer without a pre-generated CLR proxy represents a remote typed
+        // record as Record. Materialize it into the function's declared local
+        // IRecord type so dynamic resources retain their strongly typed
+        // invocation contract across the wire.
+        if (value is Record record && typeof(IRecord).IsAssignableFrom(toUnderlying))
+            return ConvertRecord(record, toUnderlying, opts);
+
         // Collections early
         {
             bool handled;
@@ -233,6 +244,34 @@ public static class RuntimeCaster
         }
     }
 
+    private static object ConvertRecord(Record record, Type targetType, RuntimeCastOptions opts)
+    {
+        if (targetType.IsAbstract || targetType.IsInterface)
+            throw new InvalidCastException("Cannot materialize a record as " + targetType + ".");
+
+        var target = Activator.CreateInstance(targetType)
+            ?? throw new InvalidCastException("Cannot create " + targetType + ".");
+        var properties = _recordPropertyCache.GetOrAdd(
+            targetType,
+            static type => type.GetProperties(BindingFlags.Instance | BindingFlags.Public)
+                .Where(property =>
+                    property.CanWrite &&
+                    property.SetMethod?.IsPublic == true &&
+                    property.GetIndexParameters().Length == 0)
+                .ToArray());
+
+        foreach (var property in properties)
+        {
+            if (!record.ContainsKey(property.Name))
+                continue;
+
+            var converted = Cast(record[property.Name], property.PropertyType, opts);
+            property.SetValue(target, converted);
+        }
+
+        return target;
+    }
+
     private static object? ConvertCollectionsIfAny(object value, Type fromType, Type toType, RuntimeCastOptions opts, out bool handled)
     {
         handled = false;

Libraries/Esiur/Data/Types/RemoteTypeDef.cs

@@ -189,7 +189,12 @@ public class RemoteTypeDef:TypeDef
         definition._content = data.Clip(offset, contentLength);
         definition._typeId = info.Id;
         definition._parentTypeId = info.Parent;
-        definition._typeName = string.IsNullOrEmpty(info.Namespace)
+        // Older TypeDefInfo producers put the fully-qualified name in Name
+        // while also filling Namespace. Avoid duplicating the namespace, but
+        // continue accepting producers that send a simple type name.
+        definition._typeName = string.IsNullOrEmpty(info.Namespace) ||
+                               info.Name.StartsWith(info.Namespace + ".", StringComparison.Ordinal) ||
+                               info.Name.StartsWith(info.Namespace + "+", StringComparison.Ordinal)
             ? info.Name
             : $"{info.Namespace}.{info.Name}";
         definition._typeDefKind = info.Kind;

Libraries/Esiur/Esiur.csproj

@@ -5,7 +5,7 @@
 		<Copyright>Ahmed Kh. Zamil</Copyright>
 		<PackageProjectUrl>https://www.esiur.com</PackageProjectUrl>
 		<GeneratePackageOnBuild>true</GeneratePackageOnBuild>
-		<Version>3.0.1</Version>
+		<Version>3.1.0</Version>
 		<RepositoryUrl>https://github.com/esiur/esiur-dotnet</RepositoryUrl>
 		<Authors>Ahmed Kh. Zamil</Authors>
 		<AssemblyVersion></AssemblyVersion>

Libraries/Esiur/Net/Packets/EpPacketRequest.cs

@@ -11,6 +11,7 @@ namespace Esiur.Net.Packets
         SetProperty = 0x1,
         Subscribe = 0x2,
         Unsubscribe = 0x3,
+        QueryResourceJournal = 0x4,
 
         // Request Inquire
         TypeDefIdsByNames = 0x8,

Libraries/Esiur/Protocol/EpConnection.cs

@@ -135,7 +135,7 @@ public partial class EpConnection : NetworkConnection, IStore
     long _authenticationAttemptGeneration;
 
     string _hostname;
-    ushort _port;
+    ushort _port = EpProtocol.DefaultPort;
 
     bool _initialPacket = true;
     AuthenticationDirection _authDirection = AuthenticationDirection.Responder;
@@ -456,6 +456,12 @@ public partial class EpConnection : NetworkConnection, IStore
 
         var headers = _session.LocalHeaders.Copy();
 
+        // Anonymous sessions still exchange typed records. They therefore
+        // need a non-empty schema namespace just like authenticated sessions;
+        // otherwise the responder cannot cache a fetched RemoteTypeDef.
+        if (string.IsNullOrWhiteSpace(headers.Domain))
+            headers.Domain = _remoteDomain ?? _hostname ?? "anonymous";
+
         if (_session.AuthenticationMode != AuthenticationMode.None)
         {
             if (_session.AuthenticationHandler == null)
@@ -1215,9 +1221,9 @@ public partial class EpConnection : NetworkConnection, IStore
         _queue.Then((x) =>
         {
             if (x.Type == EpResourceQueueItem.DistributedResourceQueueItemType.Event)
-                x.Resource._EmitEventByIndex(x.Index, x.Value);
+                x.Resource._EmitEventByIndex(x.Index, x.Value, x.Cursor, x.RecordedAt);
             else
-                x.Resource._UpdatePropertyByIndex(x.Index, x.Value);
+                x.Resource._UpdatePropertyByIndex(x.Index, x.Value, x.Cursor, x.RecordedAt);
         }).Error(e =>
         {
             // do nothing
@@ -1377,6 +1383,9 @@ public partial class EpConnection : NetworkConnection, IStore
                         case EpPacketRequest.Unsubscribe:
                             EpRequestUnsubscribe(_packet.CallbackId, dt);
                             break;
+                        case EpPacketRequest.QueryResourceJournal:
+                            EpRequestQueryResourceJournal(_packet.CallbackId, dt);
+                            break;
                         // Inquire
                         case EpPacketRequest.TypeDefIdsByNames:
                             EpRequestTypeDefIdsByNames(_packet.CallbackId, dt);
@@ -1635,6 +1644,14 @@ public partial class EpConnection : NetworkConnection, IStore
                     }
 
                     _session.RemoteHeaders = remoteHeaders;
+                    // Responder-side connections do not pass through the
+                    // outbound EpConnectionContext path that initializes
+                    // _remoteDomain. Keep the peer schema namespace from the
+                    // authentication headers so typed records sent from the
+                    // initiator can register and resolve their TypeDefs.
+                    _remoteDomain = string.IsNullOrWhiteSpace(remoteHeaders.Domain)
+                        ? $"anonymous:{RemoteEndPoint?.Address}"
+                        : remoteHeaders.Domain;
                     _session.AuthenticationMode = _authPacket.AuthMode;
                     var localHeaders = _session.LocalHeaders.Copy();
 
@@ -3144,15 +3161,11 @@ public partial class EpConnection : NetworkConnection, IStore
 
 
             if (!Uri.TryCreate($"ep://{Instance.Name}", UriKind.Absolute, out var endpoint)
-                || string.IsNullOrWhiteSpace(endpoint.Host)
-                || endpoint.Port <= 0
-                || endpoint.Port > ushort.MaxValue)
-                throw new FormatException(
-                    "EP endpoints must include an explicit port (for example, ep://host:port)."
-                );
+                || string.IsNullOrWhiteSpace(endpoint.Host))
+                throw new FormatException("The EP endpoint is invalid.");
 
             var address = endpoint.Host;
-            var port = checked((ushort)endpoint.Port);
+            var port = ResolveEndpointPort(endpoint);
 
             // assign domain from hostname if not provided
             if (context is EpConnectionContext epContext)
@@ -3198,6 +3211,20 @@ public partial class EpConnection : NetworkConnection, IStore
         return new AsyncReply<bool>(true);
     }
 
+    internal static ushort ResolveEndpointPort(Uri endpoint)
+    {
+        if (endpoint == null)
+            throw new ArgumentNullException(nameof(endpoint));
+
+        if (endpoint.Port < 0)
+            return EpProtocol.DefaultPort;
+
+        if (endpoint.Port == 0 || endpoint.Port > ushort.MaxValue)
+            throw new FormatException("The EP endpoint port must be from 1 through 65535.");
+
+        return checked((ushort)endpoint.Port);
+    }
+
 
 
 
@@ -3568,7 +3595,7 @@ public partial class EpConnection : NetworkConnection, IStore
 
                         // Reattach using the last-known age so only properties modified while
                         // disconnected are transferred and merged, instead of re-fetching all.
-                        await Reattach(r.ResourceLink, r.Instance.Age, r);
+                        await Reattach(r.ResourceLink, r.Instance.Cursor, r);
 
                         Global.Log("EpConnection", LogType.Debug, "Restored " + r.ResourceInstanceId);
 

Libraries/Esiur/Protocol/EpConnectionProtocol.cs

@@ -530,7 +530,17 @@ partial class EpConnection
 
     internal AsyncReply SendSubscribeRequest(uint instanceId, byte index)
     {
-        return SendRequest(EpPacketRequest.Subscribe, instanceId, index);
+        return SendSubscribeRequest(instanceId, index, new ResourceCursor(Guid.Empty, 0));
+    }
+
+    internal AsyncReply SendSubscribeRequest(uint instanceId, byte index, ResourceCursor after)
+    {
+        return SendRequest(
+            EpPacketRequest.Subscribe,
+            instanceId,
+            index,
+            after.Generation.ToByteArray(),
+            after.Revision);
     }
 
     internal AsyncReply SendUnsubscribeRequest(uint instanceId, byte index)
@@ -877,12 +887,14 @@ partial class EpConnection
 
     void EpNotificationPropertyModified(PlainTdu tdu)
     {
-        // resourceId, index, value
+        // resourceId, generation, revision, recordedAt, index, value
         var (valueOffset, valueSize, args) =
-            DataDeserializer.LimitedCountListParser(tdu.Data, tdu.PayloadOffset, tdu.PayloadLength, Instance.Warehouse, 2);
+            DataDeserializer.LimitedCountListParser(tdu.Data, tdu.PayloadOffset, tdu.PayloadLength, Instance.Warehouse, 5);
 
         var rid = Convert.ToUInt32(args[0]);
-        var index = (byte)args[1];
+        var cursor = new ResourceCursor(new Guid((byte[])args[1]), Convert.ToUInt64(args[2]));
+        var recordedAt = ((DateTime)args[3]).ToUniversalTime();
+        var index = (byte)args[4];
 
         FetchResource(rid, null).Then(r =>
         {
@@ -902,14 +914,14 @@ partial class EpConnection
                     {
                         item.Trigger(new EpResourceQueueItem((EpResource)r,
                                                         EpResourceQueueItem.DistributedResourceQueueItemType.Propery,
-                                                        result, index));
+                                                        result, index, cursor, recordedAt));
                     });
                 }
                 else
                 {
                     _queue.Add(new AsyncReply<EpResourceQueueItem>(new EpResourceQueueItem((EpResource)r,
                                                     EpResourceQueueItem.DistributedResourceQueueItemType.Propery,
-                                                    value, index)), hasResource: false);
+                                                    value, index, cursor, recordedAt)), hasResource: false);
                 }
             }
 
@@ -937,13 +949,15 @@ partial class EpConnection
 
     void EpNotificationEventOccurred(PlainTdu tdu)
     {
-        // resourceId, index, value
+        // resourceId, generation, revision, recordedAt, index, value
         var (valueOffset, valueSize, args) =
             DataDeserializer.LimitedCountListParser(tdu.Data, tdu.PayloadOffset,
-                                                    tdu.PayloadLength, Instance.Warehouse, 2);
+                                                    tdu.PayloadLength, Instance.Warehouse, 5);
 
         var resourceId = Convert.ToUInt32(args[0]);
-        var index = (byte)args[1];
+        var cursor = new ResourceCursor(new Guid((byte[])args[1]), Convert.ToUInt64(args[2]));
+        var recordedAt = ((DateTime)args[3]).ToUniversalTime();
+        var index = (byte)args[4];
 
         FetchResource(resourceId, null).Then(r =>
         {
@@ -964,13 +978,15 @@ partial class EpConnection
                     asyncReply.Then((result) =>
                     {
                         item.Trigger(new EpResourceQueueItem((EpResource)r,
-                                     EpResourceQueueItem.DistributedResourceQueueItemType.Event, result, index));
+                                     EpResourceQueueItem.DistributedResourceQueueItemType.Event,
+                                     result, index, cursor, recordedAt));
                     });
                 }
                 else
                 {
                     item.Trigger(new EpResourceQueueItem((EpResource)r,
-                                  EpResourceQueueItem.DistributedResourceQueueItemType.Event, pr.Value, index));
+                                  EpResourceQueueItem.DistributedResourceQueueItemType.Event,
+                                  pr.Value, index, cursor, recordedAt));
                 }
 
             }).Error((ex) => throw ex);
@@ -1019,19 +1035,22 @@ partial class EpConnection
 
                     var r = res as IResource;
 
-                    // unsubscribe
-                    Unsubscribe(r);
-
-                    // reply ok
-                    SendReply(EpPacketReply.Completed, callback,
-                        r.Instance.Definition.Id,
-                        r.Instance.Age,
-                        r.Instance.Link,
-                        r.Instance.Hops,
-                        r.Instance.Serialize());
-
-                    // subscribe
-                    Subscribe(r);
+                    r.Instance.SynchronizeJournal(head =>
+                    {
+                        // Register live delivery before capturing/sending the
+                        // snapshot. Emission shares the journal lock, so no
+                        // revision can fall between snapshot and subscription.
+                        Unsubscribe(r);
+                        Subscribe(r);
+                        SendReply(EpPacketReply.Completed, callback,
+                            r.Instance.Definition.Id,
+                            head.Generation.ToByteArray(),
+                            head.Revision,
+                            r.Instance.Link,
+                            r.Instance.Hops,
+                            r.Instance.Serialize());
+                        return true;
+                    });
                 }
                 else
                 {
@@ -1056,12 +1075,14 @@ partial class EpConnection
         // resourceLinkOrId (string link, or uint id — a link is resolved by
         // query since a remote node's instance id is not permanent: the
         // resource may have been cleared from memory and recreated under a
-        // different id while the peer was disconnected), age
+        // different id while the peer was disconnected), generation, revision
         var (valueOffset, valueSize, args) =
             DataDeserializer.LimitedCountListParser(tdu.Data, tdu.PayloadOffset,
-                                                    tdu.PayloadLength, Instance.Warehouse, 2);
+                                                    tdu.PayloadLength, Instance.Warehouse, 3);
 
-        var age = Convert.ToUInt64(args[1]);
+        var requestedCursor = new ResourceCursor(
+            new Guid((byte[])args[1]),
+            Convert.ToUInt64(args[2]));
 
         void Resolved(IResource res)
         {
@@ -1094,22 +1115,28 @@ partial class EpConnection
 
                 var r = res;
 
-                // unsubscribe
-                Unsubscribe(r);
+                r.Instance.SynchronizeJournal(head =>
+                {
+                    var reset = requestedCursor.Generation != head.Generation;
+                    Unsubscribe(r);
+                    Subscribe(r);
 
-                // reply ok — the resolved id comes first so the caller can
-                // detect and apply an id change (link-based reattach, or the
-                // remote node recreated the resource with a new id).
-                SendReply(EpPacketReply.Completed, callback,
-                    r.Instance.Id,
-                    r.Instance.Definition.Id,
-                    r.Instance.Age,
-                    r.Instance.Link,
-                    r.Instance.Hops,
-                    r.Instance.SerializeAfter(age));
-
-                // subscribe
-                Subscribe(r);
+                    // The resolved id comes first so the caller can detect and
+                    // apply an id change. A generation change returns a full
+                    // property snapshot because the old cursor is unrelated.
+                    SendReply(EpPacketReply.Completed, callback,
+                        r.Instance.Id,
+                        r.Instance.Definition.Id,
+                        head.Generation.ToByteArray(),
+                        head.Revision,
+                        r.Instance.Link,
+                        r.Instance.Hops,
+                        reset,
+                        reset
+                            ? r.Instance.SerializeMap()
+                            : r.Instance.SerializeAfter(requestedCursor.Revision));
+                    return true;
+                });
             }
             finally
             {
@@ -1427,7 +1454,10 @@ partial class EpConnection
 
         var value = Codec.ParseSync(tdu, Instance.Warehouse);
 
-        var typeId = Convert.ToUInt32(value);
+        // TypeDef identifiers are 64-bit stable hashes. Generated definitions
+        // often happened to fit in UInt32, which hid this truncation until a
+        // dynamic resource published a full-width identifier.
+        var typeId = Convert.ToUInt64(value);
 
         var t = Instance.Warehouse.GetLocalTypeDefById(typeId);
 
@@ -1665,7 +1695,7 @@ partial class EpConnection
         var (offset, length, args) = DataDeserializer.LimitedCountListParser(tdu.Data, tdu.PayloadOffset,
                                                                      tdu.PayloadLength, Instance.Warehouse, 2);
 
-        var typeId = Convert.ToUInt32(args[0]);
+        var typeId = Convert.ToUInt64(args[0]);
         var index = (byte)args[1];
 
         var typeDef = Instance.Warehouse.GetLocalTypeDefById(typeId);
@@ -1814,6 +1844,10 @@ partial class EpConnection
                                 }
                             });
                         }
+                        else if (r is IDynamicResourceFunctionHandler dynamicHandler)
+                        {
+                            InvokeDynamicFunction(dynamicHandler, r, ft, callback, result, managerDelay);
+                        }
                         else
                         {
                             InvokeFunction(ft, callback, result, EpPacketRequest.InvokeFunction, managerDelay, r);
@@ -1846,13 +1880,61 @@ partial class EpConnection
                             }
                         });
                     }
+                    else if (r is IDynamicResourceFunctionHandler dynamicHandler)
+                    {
+                        InvokeDynamicFunction(dynamicHandler, r, ft, callback, pr.Value, managerDelay);
+                    }
                     else
                     {
                         InvokeFunction(ft, callback, pr.Value, EpPacketRequest.InvokeFunction, managerDelay, r);
                     }
                 }
-            }).Error(x => SendError(ErrorType.Management, callback, (ushort)ExceptionCode.ParseError)); ;
-        }).Error(x => SendError(ErrorType.Management, callback, (ushort)ExceptionCode.ParseError)); ;
+            }).Error(x =>
+            {
+                var summary = SummerizeException(x);
+                SendError(ErrorType.Management, callback, (ushort)ExceptionCode.ParseError, summary.Item2);
+            });
+        }).Error(x =>
+        {
+            var summary = SummerizeException(x);
+            SendError(ErrorType.Management, callback, (ushort)ExceptionCode.ParseError, summary.Item2);
+        });
+    }
+
+    void InvokeDynamicFunction(
+        IDynamicResourceFunctionHandler handler,
+        IResource resource,
+        FunctionDef function,
+        uint callback,
+        object arguments,
+        TimeSpan managerDelay)
+    {
+        ExecuteRateControlled(callback, managerDelay, () =>
+        {
+            var context = new InvocationContext(this, callback);
+            context.BindOperation(resource, function);
+            try
+            {
+                var reply = handler.InvokeResourceFunctionAsync(function.Index, arguments, context);
+                if (reply == null)
+                {
+                    SendError(ErrorType.Management, callback, (ushort)ExceptionCode.MethodNotFound);
+                    return;
+                }
+
+                reply.Then(result => SendReply(EpPacketReply.Completed, callback, result))
+                    .Error(exception =>
+                    {
+                        var (code, message) = SummerizeException(exception);
+                        SendError(ErrorType.Exception, callback, code, message);
+                    });
+            }
+            catch (Exception exception)
+            {
+                var (code, message) = SummerizeException(exception);
+                SendError(ErrorType.Exception, callback, code, message);
+            }
+        });
     }
 
 
@@ -2389,6 +2471,9 @@ partial class EpConnection
 
         var resourceId = Convert.ToUInt32(args[0]);
         var index = (byte)args[1];
+        var requestedCursor = args.Length >= 4
+            ? new ResourceCursor(new Guid((byte[])args[2]), Convert.ToUInt64(args[3]))
+            : new ResourceCursor(Guid.Empty, 0);
 
         Instance.Warehouse.GetById(resourceId).Then((r) =>
         {
@@ -2418,14 +2503,13 @@ partial class EpConnection
                     out _))
                 return;
 
-            if (r is EpResource)
+            if (!IsOperationAllowed(r, et, ActionType.ReceiveEvent))
             {
-                (r as EpResource).Subscribe(et).Then(x =>
-               {
-                   SendReply(EpPacketReply.Completed, callback);
-               }).Error(x => SendError(ErrorType.Exception, callback, (ushort)ExceptionCode.GeneralFailure));
+                SendError(ErrorType.Management, callback, (ushort)ExceptionCode.NotAllowed);
+                return;
             }
-            else
+
+            if (r is EpResource)
             {
                 lock (_subscriptionsLock)
                 {
@@ -2434,17 +2518,97 @@ partial class EpConnection
                         SendError(ErrorType.Management, callback, (ushort)ExceptionCode.NotAttached);
                         return;
                     }
-
                     if (_subscriptions[r].Contains(index))
                     {
                         SendError(ErrorType.Management, callback, (ushort)ExceptionCode.AlreadyListened);
                         return;
                     }
-
                     _subscriptions[r].Add(index);
-
-                    SendReply(EpPacketReply.Completed, callback);
                 }
+
+                (r as EpResource).Subscribe(et, requestedCursor).Then(x =>
+                {
+                    var head = r.Instance.Cursor;
+                    SendReply(EpPacketReply.Completed, callback,
+                        head.Generation.ToByteArray(), head.Revision);
+                }).Error(x =>
+                {
+                    lock (_subscriptionsLock) _subscriptions[r].Remove(index);
+                    SendError(ErrorType.Exception, callback, (ushort)ExceptionCode.GeneralFailure);
+                });
+            }
+            else
+            {
+                r.Instance.SynchronizeJournal(head =>
+                {
+                    lock (_subscriptionsLock)
+                    {
+                        if (!_subscriptions.ContainsKey(r))
+                        {
+                            SendError(ErrorType.Management, callback, (ushort)ExceptionCode.NotAttached);
+                            return false;
+                        }
+
+                        if (_subscriptions[r].Contains(index))
+                        {
+                            SendError(ErrorType.Management, callback, (ushort)ExceptionCode.AlreadyListened);
+                            return false;
+                        }
+
+                        _subscriptions[r].Add(index);
+                    }
+
+                    var after = requestedCursor.Generation == Guid.Empty
+                        ? head
+                        : requestedCursor;
+
+                    if (et.Historical)
+                    {
+                        var replayAfter = after;
+                        while (true)
+                        {
+                            var page = r.Instance.QueryJournal(new ResourceJournalQuery
+                            {
+                                After = replayAfter,
+                                ThroughRevision = head.Revision,
+                                Kind = ResourceJournalEntryKind.EventOccurred,
+                                MemberIndex = index,
+                                Limit = 10000,
+                            });
+
+                            if (page.CursorExpired)
+                            {
+                                lock (_subscriptionsLock) _subscriptions[r].Remove(index);
+                                SendError(
+                                    ErrorType.Management,
+                                    callback,
+                                    (ushort)ExceptionCode.CursorExpired,
+                                    $"The requested cursor is older than {page.OldestAvailable}.");
+                                return false;
+                            }
+
+                            foreach (var entry in page.Entries)
+                                SendNotification(EpPacketNotification.EventOccurred,
+                                    r.Instance.Id,
+                                    entry.Cursor.Generation.ToByteArray(),
+                                    entry.Cursor.Revision,
+                                    entry.RecordedAt,
+                                    entry.MemberIndex,
+                                    entry.Value);
+
+                            if (!page.HasMore)
+                                break;
+                            if (page.Next == replayAfter)
+                                throw new InvalidOperationException(
+                                    "The resource journal did not advance while replaying a page.");
+                            replayAfter = page.Next;
+                        }
+                    }
+
+                    SendReply(EpPacketReply.Completed, callback,
+                        head.Generation.ToByteArray(), head.Revision);
+                    return true;
+                });
             }
         });
 
@@ -2491,6 +2655,9 @@ partial class EpConnection
             {
                 (r as EpResource).Unsubscribe(et).Then(x =>
                 {
+                    lock (_subscriptionsLock)
+                        if (_subscriptions.ContainsKey(r))
+                            _subscriptions[r].Remove(index);
                     SendReply(EpPacketReply.Completed, callback);
                 }).Error(x => SendError(ErrorType.Exception, callback, (ushort)ExceptionCode.GeneralFailure));
             }
@@ -2518,6 +2685,141 @@ partial class EpConnection
         });
     }
 
+    void EpRequestQueryResourceJournal(uint callback, PlainTdu tdu)
+    {
+        // resourceId, generation, afterRevision, throughRevision?, fromTime?,
+        // toTime?, kind?, memberIndex?, limit
+        var (_, _, args) = DataDeserializer.LimitedCountListParser(
+            tdu.Data,
+            tdu.PayloadOffset,
+            tdu.PayloadLength,
+            Instance.Warehouse,
+            9);
+
+        var resourceId = Convert.ToUInt32(args[0]);
+        var query = new ResourceJournalQuery
+        {
+            After = new ResourceCursor(new Guid((byte[])args[1]), Convert.ToUInt64(args[2])),
+            ThroughRevision = args[3] == null ? null : Convert.ToUInt64(args[3]),
+            FromTime = args[4] as DateTime?,
+            ToTime = args[5] as DateTime?,
+            Kind = args[6] == null
+                ? null
+                : (ResourceJournalEntryKind?)Convert.ToByte(args[6]),
+            MemberIndex = args[7] == null ? null : (byte?)Convert.ToByte(args[7]),
+            Limit = Convert.ToInt32(args[8]),
+        };
+
+        Instance.Warehouse.GetById(resourceId).Then(resource =>
+        {
+            if (resource == null)
+            {
+                SendError(ErrorType.Management, callback, (ushort)ExceptionCode.ResourceNotFound);
+                return;
+            }
+
+            lock (_subscriptionsLock)
+            {
+                if (!_subscriptions.ContainsKey(resource))
+                {
+                    SendError(ErrorType.Management, callback, (ushort)ExceptionCode.NotAttached);
+                    return;
+                }
+            }
+
+            var page = resource.Instance.QueryJournal(query);
+            var permitted = page.Entries.Where(entry =>
+            {
+                MemberDef member;
+                ActionType action;
+                if (entry.Kind == ResourceJournalEntryKind.PropertyModified)
+                {
+                    member = resource.Instance.Definition.GetPropertyDefByIndex(entry.MemberIndex);
+                    action = ActionType.GetProperty;
+                }
+                else
+                {
+                    member = resource.Instance.Definition.GetEventDefByIndex(entry.MemberIndex);
+                    action = ActionType.ReceiveEvent;
+                }
+
+                return member != null && IsOperationAllowed(resource, member, action);
+            }).Select(entry => (object)new object[]
+            {
+                entry.Cursor.Generation.ToByteArray(),
+                entry.Cursor.Revision,
+                entry.RecordedAt,
+                (byte)entry.Kind,
+                entry.MemberIndex,
+                entry.Value,
+            }).ToArray();
+
+            SendReply(EpPacketReply.Completed, callback,
+                page.OldestAvailable.Generation.ToByteArray(),
+                page.OldestAvailable.Revision,
+                page.HighWatermark.Generation.ToByteArray(),
+                page.HighWatermark.Revision,
+                page.Next.Generation.ToByteArray(),
+                page.Next.Revision,
+                page.CursorExpired,
+                page.HasMore,
+                permitted);
+        }).Error(exception =>
+            SendError(ErrorType.Exception, callback, (ushort)ExceptionCode.GeneralFailure, exception.Message));
+    }
+
+    /// <summary>Queries retained resource changes without changing live subscriptions.</summary>
+    public AsyncReply<ResourceJournalPage> QueryResourceJournal(
+        uint resourceId,
+        ResourceJournalQuery query)
+    {
+        query ??= new ResourceJournalQuery();
+        var reply = new AsyncReply<ResourceJournalPage>();
+        SendRequest(
+            EpPacketRequest.QueryResourceJournal,
+            resourceId,
+            query.After.Generation.ToByteArray(),
+            query.After.Revision,
+            query.ThroughRevision,
+            query.FromTime,
+            query.ToTime,
+            query.Kind.HasValue ? (object)(byte)query.Kind.Value : null,
+            query.MemberIndex,
+            query.Limit).Then(result =>
+        {
+            try
+            {
+                var values = (object[])result;
+                var entries = ((object[])values[8]).Select(raw =>
+                {
+                    var item = (object[])raw;
+                    return new ResourceJournalEntry(
+                        new ResourceCursor(new Guid((byte[])item[0]), Convert.ToUInt64(item[1])),
+                        ((DateTime)item[2]).ToUniversalTime(),
+                        (ResourceJournalEntryKind)Convert.ToByte(item[3]),
+                        Convert.ToByte(item[4]),
+                        item[5]);
+                }).ToArray();
+
+                reply.Trigger(new ResourceJournalPage(
+                    new ResourceCursor(new Guid((byte[])values[0]), Convert.ToUInt64(values[1])),
+                    new ResourceCursor(new Guid((byte[])values[2]), Convert.ToUInt64(values[3])),
+                    new ResourceCursor(new Guid((byte[])values[4]), Convert.ToUInt64(values[5])),
+                    Convert.ToBoolean(values[6]),
+                    Convert.ToBoolean(values[7]),
+                    entries));
+            }
+            catch (Exception exception)
+            {
+                reply.TriggerError(new AsyncException(
+                    ErrorType.Management,
+                    (ushort)ExceptionCode.ParseError,
+                    exception.Message));
+            }
+        }).Error(reply.TriggerError);
+        return reply;
+    }
+
 
 
 
@@ -3151,13 +3453,15 @@ partial class EpConnection
                             return;
                         }
 
-                        // TypeId, Age, Link, Hops, PropertyValue[]
+                        // TypeId, Generation, Revision, Link, Hops, PropertyValue[]
                         var args = (object[])result;
-                        var typeId = Convert.ToUInt32(args[0]);
-                        var age = Convert.ToUInt64(args[1]);
-                        var link = (string)args[2];
-                        var hops = (byte)args[3];
-                        var pvData = (byte[])args[4];
+                        var typeId = Convert.ToUInt64(args[0]);
+                        var cursor = new ResourceCursor(
+                            new Guid((byte[])args[1]),
+                            Convert.ToUInt64(args[2]));
+                        var link = (string)args[3];
+                        var hops = (byte)args[4];
+                        var pvData = (byte[])args[5];
 
 
                         var typeDef = resource != null ?
@@ -3176,7 +3480,7 @@ partial class EpConnection
                             {
                                 var pvs = results as PropertyValue[];
 
-                                dr._Attach(pvs);
+                                dr._Attach(pvs, cursor);
                                 // Progress signal: a resource has fully attached. Used by tests to
                                 // distinguish a true deadlock (no progress while requests pend) from
                                 // merely slow processing (these counters keep advancing).
@@ -3201,9 +3505,9 @@ partial class EpConnection
                                 if (resource == null)
                                 {
                                     if (td.ProxyType != null)
-                                        resource = Activator.CreateInstance(td.ProxyType, this, id, Convert.ToUInt64(args[1]), (string)args[2]) as EpResource;
+                                        resource = Activator.CreateInstance(td.ProxyType, this, id, cursor.Revision, link) as EpResource;
                                     else
-                                        resource = new EpResource(this, id, Convert.ToUInt64(args[1]), (string)args[2]);
+                                        resource = new EpResource(this, id, cursor.Revision, link);
 
                                     resource.ResourceDefinition = td;
                                     typeDef = td;
@@ -3226,9 +3530,9 @@ partial class EpConnection
                             if (resource == null)
                             {
                                 if (typeDef.ProxyType != null)
-                                    resource = Activator.CreateInstance(typeDef.ProxyType, this, id, Convert.ToUInt64(args[1]), (string)args[2]) as EpResource;
+                                    resource = Activator.CreateInstance(typeDef.ProxyType, this, id, cursor.Revision, link) as EpResource;
                                 else
-                                    resource = new EpResource(this, id, Convert.ToUInt64(args[1]), (string)args[2]);
+                                    resource = new EpResource(this, id, cursor.Revision, link);
 
                                 resource.ResourceDefinition = typeDef;
 
@@ -3266,8 +3570,8 @@ partial class EpConnection
     /// <returns>DistributedResource</returns>
     /// 
     /// <summary>
-    /// Re-attaches an already-known resource after reconnection using its last-known age. The peer
-    /// returns only the properties modified after <paramref name="age"/> (the delta), which are
+    /// Re-attaches an already-known resource after reconnection using its last-known cursor. The peer
+    /// returns only the properties modified after <paramref name="cursor"/> (the delta), which are
     /// merged into the existing instance instead of re-fetching everything. Falls back to a full
     /// <see cref="FetchResource"/> if there is no prior state to merge into.
     /// </summary>
@@ -3277,7 +3581,10 @@ partial class EpConnection
     /// under a different id while disconnected), but the link is — passing it resolves the current
     /// id and reattaches in a single round trip instead of a separate GetResourceIdByLink first.
     /// </param>
-    public AsyncReply<EpResource> Reattach(object resourceLinkOrId, ulong age, EpResource resource)
+    public AsyncReply<EpResource> Reattach(
+        object resourceLinkOrId,
+        ResourceCursor cursor,
+        EpResource resource)
     {
         // The already-attached / already-in-flight fast paths only apply when we
         // already know a specific id — a link's current id isn't known until the
@@ -3300,7 +3607,11 @@ partial class EpConnection
 
         var reply = new AsyncReply<EpResource>();
         ResourceAttachRequestCount++;
-        SendRequest(EpPacketRequest.ReattachResource, resourceLinkOrId, age).Then(result =>
+        SendRequest(
+            EpPacketRequest.ReattachResource,
+            resourceLinkOrId,
+            cursor.Generation.ToByteArray(),
+            cursor.Revision).Then(result =>
         {
             if (result == null)
             {
@@ -3309,10 +3620,13 @@ partial class EpConnection
                 return;
             }
 
-            // resolvedId, typeId, age, link, hops, delta(index -> PropertyValue)
+            // resolvedId, typeId, generation, revision, link, hops, reset, delta
             var args = (object[])result;
             var resolvedId = Convert.ToUInt32(args[0]);
-            var deltaData = (byte[])args[5];
+            var remoteCursor = new ResourceCursor(
+                new Guid((byte[])args[2]),
+                Convert.ToUInt64(args[3]));
+            var deltaData = (byte[])args[7];
             var sequence = new uint[] { resolvedId };
             var oldId = resource.ResourceInstanceId;
 
@@ -3354,7 +3668,7 @@ partial class EpConnection
                         // request that happens to share the reused oldId.
                     }
 
-                    if (!resource._Reattach(delta))
+                    if (!resource._Reattach(delta, remoteCursor))
                     {
                         // No prior state to merge into — perform a full attach instead.
                         _resourceRequests.Remove(resolvedId);
@@ -3660,6 +3974,9 @@ partial class EpConnection
     {
         SendNotification(EpPacketNotification.PropertyModified,
                          info.Resource.Instance.Id,
+                         info.Cursor.Generation.ToByteArray(),
+                         info.Cursor.Revision,
+                         info.RecordedAt,
                          info.PropertyDef.Index,
                          info.Value);
     }
@@ -3689,6 +4006,9 @@ partial class EpConnection
         // compose the packet
         SendNotification(EpPacketNotification.EventOccurred,
                           info.Resource.Instance.Id,
+                          info.Cursor.Generation.ToByteArray(),
+                          info.Cursor.Revision,
+                          info.RecordedAt,
                           info.EventDef.Index,
                           info.Value);
     }
@@ -3714,6 +4034,9 @@ partial class EpConnection
         // compose the packet
         SendNotification(EpPacketNotification.EventOccurred,
             info.Resource.Instance.Id,
+            info.Cursor.Generation.ToByteArray(),
+            info.Cursor.Revision,
+            info.RecordedAt,
             info.Definition.Index,
             info.Value);
     }

Libraries/Esiur/Protocol/EpProtocol.cs

@@ -0,0 +1,12 @@
+namespace Esiur.Protocol;
+
+/// <summary>
+/// Shared defaults for the Esiur EP protocol.
+/// </summary>
+public static class EpProtocol
+{
+    /// <summary>
+    /// Default native EP port used when a server or endpoint does not specify one.
+    /// </summary>
+    public const ushort DefaultPort = 51018;
+}

Libraries/Esiur/Protocol/EpResource.cs

@@ -89,8 +89,16 @@ public class EpResource : DynamicObject, IResource, INotifyPropertyChanged, IDyn
     // before sending a Subscribe/Unsubscribe request, since the server errors
     // (AlreadyListened/AlreadyUnsubscribed) on a redundant one.
     readonly HashSet<byte> _subscribedEvents = new();
+    // Last committed occurrence for each event. The sequence belongs to the
+    // resource-wide journal; separate checkpoints let subscriptions filter
+    // unrelated members without losing replay position.
+    readonly Dictionary<byte, ResourceCursor> _eventCursors = new();
     // Event indices with a subscription-reconciliation loop currently running.
     readonly HashSet<byte> _reconciling = new();
+    // Callers of OnAsync wait here until the shared reconciliation loop has
+    // confirmed the server-side subscription. This prevents an invocation
+    // from racing the first Subscribe request on a newly attached proxy.
+    readonly Dictionary<byte, List<AsyncReply>> _subscriptionWaiters = new();
 
 
 
@@ -219,7 +227,7 @@ public class EpResource : DynamicObject, IResource, INotifyPropertyChanged, IDyn
         this._age = age;
     }
 
-    internal bool _Attach(PropertyValue[] properties)
+    internal bool _Attach(PropertyValue[] properties, ResourceCursor cursor)
     {
         if (_status == ResourceStatus.Attached)
             return false;
@@ -235,6 +243,11 @@ public class EpResource : DynamicObject, IResource, INotifyPropertyChanged, IDyn
             this._properties[i] = properties[i].Value;
         }
 
+        Instance.ObserveRemoteCursor(cursor, DateTime.MinValue);
+        lock (_eventCursors)
+            foreach (var eventDef in Instance.Definition.Events)
+                _eventCursors[eventDef.Index] = cursor;
+
         // trigger holded events/property updates.
         //foreach (var r in afterAttachmentTriggers)
         //    r.Key.Trigger(r.Value);
@@ -255,11 +268,13 @@ public class EpResource : DynamicObject, IResource, INotifyPropertyChanged, IDyn
     /// prior state to merge into), in which case the caller should perform a full attach.
     /// </summary>
     /// <param name="delta">Modified properties keyed by their property index.</param>
-    internal bool _Reattach(Map<byte, PropertyValue> delta)
+    internal bool _Reattach(Map<byte, PropertyValue> delta, ResourceCursor cursor)
     {
         if (_properties == null || _events == null)
             return false; // no prior state — caller should perform a full attach instead.
 
+        var generationChanged = Instance.Generation != cursor.Generation;
+
         foreach (var kv in delta)
         {
             var index = kv.Key;
@@ -271,6 +286,14 @@ public class EpResource : DynamicObject, IResource, INotifyPropertyChanged, IDyn
             _properties[index] = kv.Value.Value;
         }
 
+        Instance.ObserveRemoteCursor(cursor, DateTime.MinValue);
+        if (generationChanged)
+        {
+            lock (_eventCursors)
+                foreach (var eventDef in Instance.Definition.Events)
+                    _eventCursors[eventDef.Index] = cursor;
+        }
+
         _status = Resource.ResourceStatus.Attached;
         // A reattach can follow an unexpected disconnect + automatic
         // reconnect: the server-side subscription state keyed to the old,
@@ -282,11 +305,23 @@ public class EpResource : DynamicObject, IResource, INotifyPropertyChanged, IDyn
     }
 
 
-    protected internal virtual void _EmitEventByIndex(byte index, object args)
+    protected internal virtual void _EmitEventByIndex(
+        byte index,
+        object args,
+        ResourceCursor cursor,
+        DateTime recordedAt)
     {
         var et = Instance.Definition.GetEventDefByIndex(index);
+        lock (_eventCursors)
+        {
+            if (_eventCursors.TryGetValue(index, out var previous) &&
+                previous.Generation == cursor.Generation &&
+                previous.Revision >= cursor.Revision)
+                return;
+            _eventCursors[index] = cursor;
+        }
         _events[index]?.Invoke(this, args);
-        Instance.EmitResourceEvent(et, args);
+        Instance.ApplyRemoteEvent(et, args, cursor, recordedAt);
         DispatchListeners(_eventListeners, index, args);
     }
 
@@ -346,14 +381,38 @@ public class EpResource : DynamicObject, IResource, INotifyPropertyChanged, IDyn
             return rt;
         }
 
-        if (!et.Subscribable)
+        if (!et.Subscribable && !et.Historical)
         {
             var rt = new AsyncReply();
             rt.TriggerError(new AsyncException(ErrorType.Management, (ushort)ExceptionCode.NotSubscribable, ""));
             return rt;
         }
 
-        return _connection.SendSubscribeRequest(_instanceId, et.Index);
+        ResourceCursor cursor;
+        lock (_eventCursors)
+            cursor = _eventCursors.TryGetValue(et.Index, out var known)
+                ? known
+                : Instance.Cursor;
+        return _connection.SendSubscribeRequest(_instanceId, et.Index, cursor);
+    }
+
+    internal AsyncReply Subscribe(EventDef et, ResourceCursor after)
+    {
+        if (et == null)
+        {
+            var reply = new AsyncReply();
+            reply.TriggerError(new AsyncException(
+                ErrorType.Management, (ushort)ExceptionCode.MethodNotFound, ""));
+            return reply;
+        }
+        if (!et.Subscribable && !et.Historical)
+        {
+            var reply = new AsyncReply();
+            reply.TriggerError(new AsyncException(
+                ErrorType.Management, (ushort)ExceptionCode.NotSubscribable, ""));
+            return reply;
+        }
+        return _connection.SendSubscribeRequest(_instanceId, et.Index, after);
     }
 
     public AsyncReply Subscribe(string eventName)
@@ -373,7 +432,7 @@ public class EpResource : DynamicObject, IResource, INotifyPropertyChanged, IDyn
             return rt;
         }
 
-        if (!et.Subscribable)
+        if (!et.Subscribable && !et.Historical)
         {
             var rt = new AsyncReply();
             rt.TriggerError(new AsyncException(ErrorType.Management, (ushort)ExceptionCode.NotSubscribable, ""));
@@ -390,6 +449,10 @@ public class EpResource : DynamicObject, IResource, INotifyPropertyChanged, IDyn
         return Unsubscribe(et);
     }
 
+    /// <summary>Queries retained property changes and event occurrences.</summary>
+    public AsyncReply<ResourceJournalPage> QueryJournal(ResourceJournalQuery query = null) =>
+        _connection.QueryResourceJournal(_instanceId, query ?? new ResourceJournalQuery());
+
     /// <summary>
     /// Listen for a property change (<c>On(":propName", cb)</c>) or an
     /// exported event (<c>On("eventName", cb)</c>). For events where the
@@ -401,20 +464,54 @@ public class EpResource : DynamicObject, IResource, INotifyPropertyChanged, IDyn
     /// </summary>
     public EpResource On(string name, Action<object> callback)
     {
+        OnAsync(name, callback);
+        return this;
+    }
+
+    /// <summary>
+    /// Register a listener and complete only after a subscribable event is
+    /// active on the remote endpoint. Multiple concurrent callers share the
+    /// same wire-level subscription reconciliation.
+    /// </summary>
+    public AsyncReply OnAsync(string name, Action<object> callback)
+    {
+        var reply = new AsyncReply();
         if (name.StartsWith(":"))
         {
             var propertyName = name.Substring(1);
             var pt = Instance.Definition.GetPropertyDefByName(propertyName)
                 ?? throw new Exception($"Unknown property \"{propertyName}\".");
             AddListener(_propertyListeners, pt.Index, callback);
-            return this;
+            reply.Trigger(this);
+            return reply;
         }
 
         var et = Instance.Definition.GetEventDefByName(name)
             ?? throw new Exception($"Unknown event \"{name}\".");
         AddListener(_eventListeners, et.Index, callback);
-        if (et.Subscribable) ReconcileSubscription(et);
-        return this;
+        if (et.Subscribable || et.Historical)
+            ReconcileSubscription(et, reply);
+        else
+            reply.Trigger(this);
+        return reply;
+    }
+
+    /// <summary>
+    /// Registers an event listener and replays retained occurrences newer than
+    /// <paramref name="after"/> before continuing with live delivery.
+    /// </summary>
+    public AsyncReply OnFromAsync(string name, ResourceCursor after, Action<object> callback)
+    {
+        var et = Instance.Definition.GetEventDefByName(name)
+            ?? throw new Exception($"Unknown event \"{name}\".");
+        if (!et.Historical)
+            throw new InvalidOperationException($"Event `{name}` is not historical.");
+
+        lock (_eventCursors) _eventCursors[et.Index] = after;
+        var reply = new AsyncReply();
+        AddListener(_eventListeners, et.Index, callback);
+        ReconcileSubscription(et, reply);
+        return reply;
     }
 
     /// <summary>Remove a listener registered with <see cref="On"/>.</summary>
@@ -430,7 +527,7 @@ public class EpResource : DynamicObject, IResource, INotifyPropertyChanged, IDyn
         var et = Instance.Definition.GetEventDefByName(name);
         if (et == null) return this;
         RemoveListener(_eventListeners, et.Index, callback);
-        if (et.Subscribable) ReconcileSubscription(et);
+        if (et.Subscribable || et.Historical) ReconcileSubscription(et);
         return this;
     }
 
@@ -486,7 +583,7 @@ public class EpResource : DynamicObject, IResource, INotifyPropertyChanged, IDyn
 
         foreach (var et in Instance.Definition.Events)
         {
-            if (!et.Subscribable) continue;
+            if (!et.Subscribable && !et.Historical) continue;
             var hasListeners = ListenerCount(_eventListeners, et.Index) > 0 || _events[et.Index] != null;
             if (hasListeners) ReconcileSubscription(et);
         }
@@ -500,8 +597,21 @@ public class EpResource : DynamicObject, IResource, INotifyPropertyChanged, IDyn
     /// once the in-flight request settles, rather than replaying every
     /// transition.
     /// </summary>
-    void ReconcileSubscription(EventDef et)
+    void ReconcileSubscription(EventDef et, AsyncReply waiter = null)
     {
+        if (waiter != null)
+        {
+            lock (_subscriptionWaiters)
+            {
+                if (!_subscriptionWaiters.TryGetValue(et.Index, out var waiters))
+                {
+                    waiters = new List<AsyncReply>();
+                    _subscriptionWaiters[et.Index] = waiters;
+                }
+                waiters.Add(waiter);
+            }
+        }
+
         lock (_reconciling)
         {
             if (!_reconciling.Add(et.Index)) return;
@@ -524,7 +634,7 @@ public class EpResource : DynamicObject, IResource, INotifyPropertyChanged, IDyn
 
         if (desired == actual)
         {
-            lock (_reconciling) _reconciling.Remove(et.Index);
+            CompleteSubscriptionReconciliation(et.Index, null);
             return;
         }
 
@@ -539,15 +649,37 @@ public class EpResource : DynamicObject, IResource, INotifyPropertyChanged, IDyn
             // Re-check: the desired state may have changed while this request
             // was in flight (another On()/Off() call came in meanwhile).
             StepSubscription(et);
-        }).Error((_) =>
+        }).Error((error) =>
         {
             // Leave `_subscribedEvents` as-is; the next On()/Off() call that
             // changes the listener count re-triggers reconciliation, so a
             // transient failure here just needs another transition to retry.
-            lock (_reconciling) _reconciling.Remove(et.Index);
+            CompleteSubscriptionReconciliation(et.Index, error);
         });
     }
 
+    void CompleteSubscriptionReconciliation(byte eventIndex, AsyncException error)
+    {
+        lock (_reconciling) _reconciling.Remove(eventIndex);
+
+        AsyncReply[] waiters = null;
+        lock (_subscriptionWaiters)
+        {
+            if (_subscriptionWaiters.TryGetValue(eventIndex, out var pending))
+            {
+                waiters = pending.ToArray();
+                _subscriptionWaiters.Remove(eventIndex);
+            }
+        }
+
+        if (waiters == null) return;
+        foreach (var waiter in waiters)
+        {
+            if (error == null) waiter.Trigger(this);
+            else waiter.TriggerError(error);
+        }
+    }
+
 
     public override bool TryInvokeMember(InvokeMemberBinder binder, object[] args, out object result)
     {
@@ -664,11 +796,17 @@ public class EpResource : DynamicObject, IResource, INotifyPropertyChanged, IDyn
     }
 
 
-    internal void _UpdatePropertyByIndex(byte index, object value)
+    internal void _UpdatePropertyByIndex(
+        byte index,
+        object value,
+        ResourceCursor cursor,
+        DateTime recordedAt)
     {
         var pt = Instance.Definition.GetPropertyDefByIndex(index);
+        if (!Instance.IsNewerPropertyRevision(index, cursor))
+            return;
         _properties[index] = value;
-        Instance.EmitModification(pt, value);
+        Instance.ApplyRemotePropertyModification(pt, value, cursor, recordedAt);
         DispatchListeners(_propertyListeners, index, value);
     }
 

Libraries/Esiur/Protocol/EpResourceQueueItem.cs

@@ -27,6 +27,7 @@ using System.Collections.Generic;
 using System.Linq;
 using System.Text;
 using System.Threading.Tasks;
+using Esiur.Resource;
 
 namespace Esiur.Protocol;
 public class EpResourceQueueItem
@@ -41,13 +42,23 @@ public class EpResourceQueueItem
     byte index;
     object value;
     EpResource resource;
+    ResourceCursor cursor;
+    DateTime recordedAt;
 
-    public EpResourceQueueItem(EpResource resource, DistributedResourceQueueItemType type, object value, byte index)
+    public EpResourceQueueItem(
+        EpResource resource,
+        DistributedResourceQueueItemType type,
+        object value,
+        byte index,
+        ResourceCursor cursor,
+        DateTime recordedAt)
     {
         this.resource = resource;
         this.index = index;
         this.type = type;
         this.value = value;
+        this.cursor = cursor;
+        this.recordedAt = recordedAt;
     }
 
     public EpResource Resource
@@ -68,4 +79,7 @@ public class EpResourceQueueItem
     {
         get { return value; }
     }
+
+    public ResourceCursor Cursor => cursor;
+    public DateTime RecordedAt => recordedAt;
 }

Libraries/Esiur/Protocol/EpServer.cs

@@ -44,6 +44,18 @@ namespace Esiur.Protocol;
 
 public class EpServer : NetworkServer<EpConnection>, IResource
 {
+    /// <summary>
+    /// Raised after an accepted connection has completed authentication and is
+    /// ready for bidirectional resource access. Unlike <see cref="ClientConnected"/>,
+    /// this never exposes a half-completed handshake to applications.
+    /// </summary>
+    public event EpConnection.ReadyEvent ConnectionReady;
+
+    /// <summary>
+    /// Raised when an accepted connection is removed from the server.
+    /// </summary>
+    public event Action<EpConnection> ConnectionDisconnected;
+
     sealed class PeerAttemptWindow
     {
         public DateTime StartedUtc;
@@ -132,13 +144,14 @@ public class EpServer : NetworkServer<EpConnection>, IResource
     }
 
     /// <summary>
-    /// Application-supplied native TCP port. Zero requests an ephemeral port from the OS.
+    /// Native TCP port. Defaults to <see cref="EpProtocol.DefaultPort"/>;
+    /// explicitly set zero to request an ephemeral port from the OS.
     /// </summary>
     public ushort Port
     {
         get;
         set;
-    }
+    } = EpProtocol.DefaultPort;
 
     /// <summary>
     /// Controls whether warehouse initialization opens Esiur's native TCP listener.
@@ -246,6 +259,7 @@ public class EpServer : NetworkServer<EpConnection>, IResource
             connection.ExceptionLevel = ExceptionLevel;
             connection.AuthenticationTimeout = AuthenticationTimeout;
             connection.RestartAuthenticationDeadline();
+            connection.OnReady += AcceptedConnectionReady;
             base.Add(connection);
             return true;
         }
@@ -261,6 +275,7 @@ public class EpServer : NetworkServer<EpConnection>, IResource
     {
         try
         {
+            connection.OnReady -= AcceptedConnectionReady;
             base.Remove(connection);
         }
         finally
@@ -269,6 +284,9 @@ public class EpServer : NetworkServer<EpConnection>, IResource
         }
     }
 
+    private void AcceptedConnectionReady(EpConnection connection)
+        => ConnectionReady?.Invoke(connection);
+
     private bool TryAdmitConnection(EpConnection connection, out string rejectionReason)
     {
         rejectionReason = null;
@@ -403,8 +421,7 @@ public class EpServer : NetworkServer<EpConnection>, IResource
 
     protected override void ClientDisconnected(EpConnection connection)
     {
-        //connection.OnReady -= ConnectionReadyEventReceiver;
-        //Warehouse.Remove(connection);
+        ConnectionDisconnected?.Invoke(connection);
     }
 
     public KeyList<string, CallInfo?> Calls { get; } = new KeyList<string, CallInfo?>();

Libraries/Esiur/Proxy/TypeDefGenerator.cs

@@ -533,7 +533,7 @@ public static class TypeDefGenerator
         if (typeDef.Events.Length > 0)
         {
 
-            rt.AppendLine("protected override void _EmitEventByIndex(byte index, object args) {");
+            rt.AppendLine("protected override void _EmitEventByIndex(byte index, object args, ResourceCursor cursor, DateTime recordedAt) {");
             rt.AppendLine("switch (index) {");
 
             var eventsList = new StringBuilder();
@@ -554,7 +554,9 @@ public static class TypeDefGenerator
                 eventsList.AppendLine($"[Export] public event ResourceEventHandler<{etTypeName}> {e.Name};");
             }
 
-            rt.AppendLine("}}");
+            rt.AppendLine("}");
+            rt.AppendLine("base._EmitEventByIndex(index, args, cursor, recordedAt);");
+            rt.AppendLine("}");
 
             rt.AppendLine(eventsList.ToString());
 

Libraries/Esiur/README.md

@@ -89,17 +89,17 @@ Now we can add our resource to the memory store using `warehouse.Put`.
 await warehouse.Put("sys/hello", new HelloResource());
 ```
 
-Add an `EpServer` to expose the resource through the Esiur EP protocol. Anonymous access is enabled here only to make the development example easy to run; production applications should configure an authentication provider.
+Add an `EpServer` to expose the resource through the Esiur EP protocol. The
+server and portless `ep://` client URLs use port `51018` by default; set
+`EpServer.Port` or include a URL port only when an application needs an
+override. Anonymous access is enabled here only to make the development
+example easy to run; production applications should configure an
+authentication provider.
 
 
 ```C#
-var epPort = ushort.Parse(
-    Environment.GetEnvironmentVariable("ESIUR_PORT")
-    ?? throw new InvalidOperationException("Set ESIUR_PORT."));
-
 await warehouse.Put("sys/server", new EpServer
 {
-    Port = epPort,
     AllowUnauthorizedAccess = true, // Development only.
 });
 ```
@@ -118,15 +118,11 @@ To sum up
 >using Esiur.Resource;
 >using Esiur.Stores;
 >
->var epPort = ushort.Parse(
->    Environment.GetEnvironmentVariable("ESIUR_PORT")
->    ?? throw new InvalidOperationException("Set ESIUR_PORT."));
 >var warehouse = new Warehouse();
 >await warehouse.Put("sys", new MemoryStore());
 >await warehouse.Put("sys/hello", new HelloResource());
 >await warehouse.Put("sys/server", new EpServer
 >{
->    Port = epPort,
 >    AllowUnauthorizedAccess = true, // Development only.
 >});
 >await warehouse.Open();
@@ -138,8 +134,7 @@ To access our resource remotely, we need to use it's full path including the pro
 
 ```C#
 var warehouse = new Warehouse();
-var epPort = ushort.Parse(Environment.GetEnvironmentVariable("ESIUR_PORT")!);
-dynamic res = await warehouse.Get<IResource>($"ep://localhost:{epPort}/sys/hello");
+dynamic res = await warehouse.Get<IResource>("ep://localhost/sys/hello");
 ```
 
 Now we can invoke the exported functions and read/write properties;
@@ -157,8 +152,7 @@ Summing up
 >using Esiur.Resource;
 >
 >var warehouse = new Warehouse();
->var epPort = ushort.Parse(Environment.GetEnvironmentVariable("ESIUR_PORT")!);
->dynamic res = await warehouse.Get<IResource>($"ep://localhost:{epPort}/sys/hello");
+>dynamic res = await warehouse.Get<IResource>("ep://localhost/sys/hello");
 >
 >var reply = await res.SayHi("Hi, I'm calling you from dotnet");
 >
@@ -176,7 +170,7 @@ Esiur has a self describing feature which comes with every language it supports,
 After installing the Esiur NuGet package, a new command named ***Get-Types*** is added to the Visual Studio Package Manager Console. It generates client-side classes for robust static typing.
 
 ```ps 
-Get-Types "ep://localhost:$env:ESIUR_PORT/sys/hello"
+Get-Types "ep://localhost/sys/hello"
 ```
 
 This will generate and add wrappers for all types needed by our resource.
@@ -184,8 +178,7 @@ This will generate and add wrappers for all types needed by our resource.
 Allowing us to use
 ```C#
 var warehouse = new Warehouse();
-var epPort = ushort.Parse(Environment.GetEnvironmentVariable("ESIUR_PORT")!);
-var res = await warehouse.Get<MyResource>($"ep://localhost:{epPort}/sys/hello");
+var res = await warehouse.Get<MyResource>("ep://localhost/sys/hello");
 var reply = await res.SayHi("Static typing is better");
 Console.WriteLine(reply);
 ```

Libraries/Esiur/Resource/CustomEventOccurredInfo.cs

@@ -13,15 +13,27 @@ public class CustomEventOccurredInfo
     public readonly object Value;
     public readonly object Issuer;
     public readonly Func<Session, bool> Receivers;
+    public readonly ResourceCursor Cursor;
+    public ulong Revision => Cursor.Revision;
+    public readonly DateTime RecordedAt;
 
     public string Name => EventDef.Name;
 
-    public CustomEventOccurredInfo(IResource resource, EventDef eventDef, Func<Session, bool> receivers, object issuer, object value)
+    public CustomEventOccurredInfo(
+        IResource resource,
+        EventDef eventDef,
+        Func<Session, bool> receivers,
+        object issuer,
+        object value,
+        ResourceCursor cursor,
+        DateTime recordedAt)
     {
         Resource = resource;
         EventDef = eventDef;
         Receivers = receivers;
         Issuer = issuer;
         Value = value;
+        Cursor = cursor;
+        RecordedAt = recordedAt;
     }
 }

Libraries/Esiur/Resource/EventOccurredInfo.cs

@@ -15,12 +15,27 @@ namespace Esiur.Resource
 
         public readonly IResource Resource;
         public readonly object Value;
+        public readonly ResourceCursor Cursor;
+        public ulong Revision => Cursor.Revision;
+        public readonly DateTime RecordedAt;
 
-        public EventOccurredInfo(IResource resource, EventDef eventDef, object value)
+        public EventOccurredInfo(
+            IResource resource,
+            EventDef eventDef,
+            object value,
+            ResourceCursor cursor,
+            DateTime recordedAt)
         {
             Resource = resource;
             Value = value;
             Definition = eventDef;
+            Cursor = cursor;
+            RecordedAt = recordedAt;
+        }
+
+        public EventOccurredInfo(IResource resource, EventDef eventDef, object value)
+            : this(resource, eventDef, value, new ResourceCursor(Guid.Empty, 0), DateTime.UtcNow)
+        {
         }
     }
 }

Libraries/Esiur/Resource/Instance.cs

@@ -49,6 +49,8 @@ public class Instance
 	List<ulong?> ages = new();
 	List<DateTime?> modificationDates = new();
 	private ulong instanceAge;
+	private Guid streamGeneration;
+	private readonly object journalSync = new();
 	private byte hops;
 	private DateTime instanceModificationDate;
 
@@ -331,12 +333,34 @@ public class Instance
 	}
 
 	/// <summary>
-	/// Age of the instance, incremented by 1 in every modification.
+	/// Legacy alias for the resource-wide revision. It advances for every
+	/// property modification and event occurrence.
 	/// </summary>
 	public ulong Age
 	{
-		get { return instanceAge; }
-		internal set { instanceAge = value; }
+		get { lock (journalSync) return instanceAge; }
+		internal set { lock (journalSync) instanceAge = value; }
+	}
+
+	/// <summary>
+	/// Current resource revision. Unlike the legacy property-only age, this
+	/// advances for every property modification and event occurrence.
+	/// </summary>
+	public ulong Revision
+	{
+		get { lock (journalSync) return instanceAge; }
+	}
+
+	/// <summary>Generation of the current resource change stream.</summary>
+	public Guid Generation
+	{
+		get { lock (journalSync) return streamGeneration; }
+	}
+
+	/// <summary>Current replay cursor for the resource.</summary>
+	public ResourceCursor Cursor
+	{
+		get { lock (journalSync) return new ResourceCursor(streamGeneration, instanceAge); }
 	}
 
 	/// <summary>
@@ -454,6 +478,16 @@ public class Instance
 		return props;
 	}
 
+	/// <summary>Exports every property keyed by its member index.</summary>
+	public Map<byte, PropertyValue> SerializeMap()
+	{
+		var values = Serialize();
+		var map = new Map<byte, PropertyValue>();
+		for (byte index = 0; index < values.Length; index++)
+			map.Add(index, values[index]);
+		return map;
+	}
+
 
 	/// <summary>
 	/// If True, the instance can be stored to disk.
@@ -477,24 +511,25 @@ public class Instance
 		IResource res;
 		if (this.resource.TryGetTarget(out res))
 		{
-			instanceAge++;
-			var now = DateTime.UtcNow;
+			lock (journalSync)
+			{
+				var cursor = NextCursor();
+				var now = DateTime.UtcNow;
 
-			ages[pt.Index] = instanceAge;
-			modificationDates[pt.Index] = now;
+				ages[pt.Index] = cursor.Revision;
+				modificationDates[pt.Index] = now;
+				instanceModificationDate = now;
 
-			//if (pt.HasHistory)
-			//{
-			//    store.Record(res, pt.Name, value, ages[pt.Index], now);
-			//}
-			//else //if (pt.Storage == StorageMode.Recordable)
-			//{
-			store.Modify(res, pt, value, ages[pt.Index], now);
-			//}
+				store.Modify(res, pt, value, cursor.Revision, now);
+				CommitJournal(res, new ResourceJournalEntry(
+					cursor,
+					now,
+					ResourceJournalEntryKind.PropertyModified,
+					pt.Index,
+					value), pt.Historical);
 
-			//ResourceModified?.Invoke(res, pt.Name, value);
-
-			PropertyModified?.Invoke(new PropertyModificationInfo(res, pt, value, instanceAge));
+				PropertyModified?.Invoke(new PropertyModificationInfo(res, pt, value, cursor, now));
+			}
 		}
 	}
 
@@ -526,7 +561,21 @@ public class Instance
 		IResource res;
 		if (this.resource.TryGetTarget(out res))
 		{
-			CustomEventOccurred?.Invoke(new CustomEventOccurredInfo(res, eventDef, receivers, issuer, value));
+			lock (journalSync)
+			{
+				var cursor = NextCursor();
+				var now = DateTime.UtcNow;
+				instanceModificationDate = now;
+				// Receiver predicates are session-specific and cannot be replayed safely.
+				CommitJournal(res, new ResourceJournalEntry(
+					cursor,
+					now,
+					ResourceJournalEntryKind.EventOccurred,
+					eventDef.Index,
+					value), false);
+				CustomEventOccurred?.Invoke(new CustomEventOccurredInfo(
+					res, eventDef, receivers, issuer, value, cursor, now));
+			}
 		}
 	}
 
@@ -535,7 +584,7 @@ public class Instance
 		IResource res;
 		if (this.resource.TryGetTarget(out res))
 		{
-			EventOccurred?.Invoke(new EventOccurredInfo(res, eventDef, value));
+			EmitResourceEventCore(res, eventDef, value);
 		}
 	}
 
@@ -545,7 +594,7 @@ public class Instance
 		if (this.resource.TryGetTarget(out res))
 		{
 			var eventDef = definition.GetEventDefByIndex(eventIndex);
-			EventOccurred?.Invoke(new EventOccurredInfo(res, eventDef, value));
+			EmitResourceEventCore(res, eventDef, value);
 		}
 	}
 
@@ -555,7 +604,141 @@ public class Instance
 		if (this.resource.TryGetTarget(out res))
 		{
 			var eventDef = definition.GetEventDefByIndex(eventIndex);
-			CustomEventOccurred?.Invoke(new CustomEventOccurredInfo(res, eventDef, receivers, issuer, value));
+			EmitCustomResourceEvent(issuer, receivers, eventDef, value);
+		}
+	}
+
+	void EmitResourceEventCore(IResource res, EventDef eventDef, object value)
+	{
+		if (eventDef == null)
+			return;
+
+		lock (journalSync)
+		{
+			var cursor = NextCursor();
+			var now = DateTime.UtcNow;
+			instanceModificationDate = now;
+			CommitJournal(res, new ResourceJournalEntry(
+				cursor,
+				now,
+				ResourceJournalEntryKind.EventOccurred,
+				eventDef.Index,
+				value), eventDef.Historical);
+			EventOccurred?.Invoke(new EventOccurredInfo(res, eventDef, value, cursor, now));
+		}
+	}
+
+	ResourceCursor NextCursor()
+	{
+		instanceAge++;
+		return new ResourceCursor(streamGeneration, instanceAge);
+	}
+
+	void CommitJournal(IResource res, ResourceJournalEntry entry, bool retain)
+	{
+		if (store is IResourceJournalStore journal &&
+			!journal.AppendJournalEntry(res, entry, retain))
+			throw new InvalidOperationException(
+				$"The store rejected resource journal revision {entry.Cursor} for `{Link}`.");
+	}
+
+	/// <summary>Reads retained changes from this resource's owning store.</summary>
+	public ResourceJournalPage QueryJournal(ResourceJournalQuery query)
+	{
+		lock (journalSync)
+		{
+			if (resource.TryGetTarget(out var res) && store is IResourceJournalStore journal)
+			{
+				var page = journal.QueryJournal(res, query ?? new ResourceJournalQuery());
+				var cursor = new ResourceCursor(streamGeneration, instanceAge);
+				if (page.HighWatermark == cursor)
+					return page;
+
+				return new ResourceJournalPage(
+					page.OldestAvailable,
+					cursor,
+					page.Next,
+					page.CursorExpired,
+					page.HasMore,
+					page.Entries);
+			}
+
+			var currentCursor = new ResourceCursor(streamGeneration, instanceAge);
+			return new ResourceJournalPage(currentCursor, currentCursor, query?.After ?? currentCursor,
+				false, false, Array.Empty<ResourceJournalEntry>());
+		}
+	}
+
+	/// <summary>
+	/// Runs an attach/replay operation against an atomic resource high-watermark.
+	/// Emission uses the same lock, so notifications after the callback are live
+	/// changes strictly newer than the captured cursor.
+	/// </summary>
+	internal T SynchronizeJournal<T>(Func<ResourceCursor, T> action)
+	{
+		lock (journalSync)
+			return action(new ResourceCursor(streamGeneration, instanceAge));
+	}
+
+	internal void ObserveRemoteCursor(ResourceCursor cursor, DateTime recordedAt)
+	{
+		lock (journalSync)
+		{
+			if (streamGeneration != cursor.Generation)
+			{
+				streamGeneration = cursor.Generation;
+				instanceAge = cursor.Revision;
+			}
+			else if (cursor.Revision > instanceAge)
+				instanceAge = cursor.Revision;
+
+			if (recordedAt > instanceModificationDate)
+				instanceModificationDate = recordedAt;
+		}
+	}
+
+	internal bool IsNewerPropertyRevision(byte index, ResourceCursor cursor)
+	{
+		lock (journalSync)
+		{
+			if (streamGeneration != cursor.Generation)
+				return true;
+			return index >= ages.Count || !ages[index].HasValue || ages[index].Value < cursor.Revision;
+		}
+	}
+
+	internal void ApplyRemotePropertyModification(
+		PropertyDef propertyDef,
+		object value,
+		ResourceCursor cursor,
+		DateTime recordedAt)
+	{
+		if (!resource.TryGetTarget(out var res))
+			return;
+
+		lock (journalSync)
+		{
+			ObserveRemoteCursor(cursor, recordedAt);
+			ages[propertyDef.Index] = cursor.Revision;
+			modificationDates[propertyDef.Index] = recordedAt;
+			PropertyModified?.Invoke(new PropertyModificationInfo(
+				res, propertyDef, value, cursor, recordedAt));
+		}
+	}
+
+	internal void ApplyRemoteEvent(
+		EventDef eventDef,
+		object value,
+		ResourceCursor cursor,
+		DateTime recordedAt)
+	{
+		if (!resource.TryGetTarget(out var res))
+			return;
+
+		lock (journalSync)
+		{
+			ObserveRemoteCursor(cursor, recordedAt);
+			EventOccurred?.Invoke(new EventOccurredInfo(res, eventDef, value, cursor, recordedAt));
 		}
 	}
 
@@ -755,7 +938,14 @@ public class Instance
 	/// <param name="name">Name of the instance.</param>
 	/// <param name="resource">Resource to manage.</param>
 	/// <param name="store">Store responsible for the resource.</param>
-	public Instance(Warehouse warehouse, uint id, string name, IResource resource, IStore store, ulong age = 0)
+	public Instance(
+		Warehouse warehouse,
+		uint id,
+		string name,
+		IResource resource,
+		IStore store,
+		ulong age = 0,
+		string resourceKey = null)
 	{
 		this.Warehouse = warehouse;
 		this.store = store;
@@ -763,6 +953,17 @@ public class Instance
 		this.id = id;
 		this.name = name ?? "";
 		this.instanceAge = age;
+		this.streamGeneration = Guid.NewGuid();
+
+		if (store is IResourceJournalStore journal)
+		{
+			var cursor = journal.OpenJournal(
+				resource,
+				resourceKey ?? name ?? string.Empty,
+				new ResourceCursor(streamGeneration, instanceAge));
+			streamGeneration = cursor.Generation;
+			instanceAge = Math.Max(instanceAge, cursor.Revision);
+		}
 
 		//this.attributes = new KeyList<string, object>(this);
 		//children = new AutoList<IResource, Instance>(this);
@@ -779,6 +980,7 @@ public class Instance
 		if (resource is IDynamicResource dynamicResource)
 		{
 			this.definition = dynamicResource.ResourceDefinition;
+			warehouse.RegisterDynamicTypeDef(this.definition);
 		}
 		else
 		{
@@ -796,6 +998,8 @@ public class Instance
 		// connect events
 		if (!(resource is EpResource))
 		{
+			if (resource is IDynamicResourceEventSource dynamicEventSource)
+				dynamicEventSource.ResourceEventOccurred += EmitResourceEventByIndex;
 
 			Type t = ResourceProxy.GetBaseType(resource);
 

Libraries/Esiur/Resource/PropertyModificationInfo.cs

@@ -12,15 +12,30 @@ public struct PropertyModificationInfo
     public readonly PropertyDef PropertyDef;
     public string Name => PropertyDef.Name;
     public readonly ulong Age;
+    public ulong Revision => Cursor.Revision;
+    public readonly ResourceCursor Cursor;
+    public readonly DateTime RecordedAt;
     public object Value;
 
-    public PropertyModificationInfo(IResource resource, PropertyDef propertyDef, object value, ulong age)
+    public PropertyModificationInfo(
+        IResource resource,
+        PropertyDef propertyDef,
+        object value,
+        ResourceCursor cursor,
+        DateTime recordedAt)
     {
         Resource = resource;
         PropertyDef = propertyDef;
-        Age = age;
+        Cursor = cursor;
+        Age = cursor.Revision;
+        RecordedAt = recordedAt;
         Value = value;
     }
+
+    public PropertyModificationInfo(IResource resource, PropertyDef propertyDef, object value, ulong age)
+        : this(resource, propertyDef, value, new ResourceCursor(Guid.Empty, age), DateTime.UtcNow)
+    {
+    }
     
 }
 

Libraries/Esiur/Resource/ResourceCursor.cs

@@ -0,0 +1,36 @@
+using System;
+
+namespace Esiur.Resource;
+
+/// <summary>
+/// Identifies an exact position in a resource's ordered change stream.
+/// Generation changes when the stream is recreated; revision increases for
+/// every observable property modification or event occurrence.
+/// </summary>
+public readonly struct ResourceCursor : IEquatable<ResourceCursor>
+{
+    public Guid Generation { get; }
+    public ulong Revision { get; }
+
+    public ResourceCursor(Guid generation, ulong revision)
+    {
+        Generation = generation;
+        Revision = revision;
+    }
+
+    public bool IsEmpty => Generation == Guid.Empty && Revision == 0;
+
+    public bool Equals(ResourceCursor other) =>
+        Generation == other.Generation && Revision == other.Revision;
+
+    public override bool Equals(object obj) =>
+        obj is ResourceCursor other && Equals(other);
+
+    public override int GetHashCode() =>
+        (Generation.GetHashCode() * 397) ^ Revision.GetHashCode();
+
+    public override string ToString() => $"{Generation:N}:{Revision}";
+
+    public static bool operator ==(ResourceCursor left, ResourceCursor right) => left.Equals(right);
+    public static bool operator !=(ResourceCursor left, ResourceCursor right) => !left.Equals(right);
+}

Libraries/Esiur/Resource/ResourceJournal.cs

@@ -0,0 +1,240 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Runtime.CompilerServices;
+
+namespace Esiur.Resource;
+
+public enum ResourceJournalEntryKind : byte
+{
+    PropertyModified = 0,
+    EventOccurred = 1,
+}
+
+/// <summary>An ordered, optionally retained resource change.</summary>
+public sealed class ResourceJournalEntry
+{
+    public ResourceCursor Cursor { get; }
+    public DateTime RecordedAt { get; }
+    public ResourceJournalEntryKind Kind { get; }
+    public byte MemberIndex { get; }
+    public object Value { get; }
+
+    public ResourceJournalEntry(
+        ResourceCursor cursor,
+        DateTime recordedAt,
+        ResourceJournalEntryKind kind,
+        byte memberIndex,
+        object value)
+    {
+        Cursor = cursor;
+        RecordedAt = recordedAt.Kind == DateTimeKind.Utc
+            ? recordedAt
+            : recordedAt.ToUniversalTime();
+        Kind = kind;
+        MemberIndex = memberIndex;
+        Value = value;
+    }
+}
+
+/// <summary>Filters a bounded resource-journal query.</summary>
+public sealed class ResourceJournalQuery
+{
+    public ResourceCursor After { get; set; }
+    public ulong? ThroughRevision { get; set; }
+    public DateTime? FromTime { get; set; }
+    public DateTime? ToTime { get; set; }
+    public ResourceJournalEntryKind? Kind { get; set; }
+    public byte? MemberIndex { get; set; }
+    public int Limit { get; set; } = 1000;
+}
+
+/// <summary>A journal page and the stream boundaries used to read it.</summary>
+public sealed class ResourceJournalPage
+{
+    public ResourceCursor OldestAvailable { get; }
+    public ResourceCursor HighWatermark { get; }
+    public ResourceCursor Next { get; }
+    public bool CursorExpired { get; }
+    public bool HasMore { get; }
+    public ResourceJournalEntry[] Entries { get; }
+
+    public ResourceJournalPage(
+        ResourceCursor oldestAvailable,
+        ResourceCursor highWatermark,
+        ResourceCursor next,
+        bool cursorExpired,
+        bool hasMore,
+        ResourceJournalEntry[] entries)
+    {
+        OldestAvailable = oldestAvailable;
+        HighWatermark = highWatermark;
+        Next = next;
+        CursorExpired = cursorExpired;
+        HasMore = hasMore;
+        Entries = entries ?? Array.Empty<ResourceJournalEntry>();
+    }
+}
+
+/// <summary>
+/// Optional store capability for persisting historical property changes and
+/// event occurrences. The resource instance owns ordering; the store owns
+/// retention and persistence.
+/// </summary>
+public interface IResourceJournalStore
+{
+    ResourceCursor OpenJournal(
+        IResource resource,
+        string resourceKey,
+        ResourceCursor proposedCursor);
+    bool AppendJournalEntry(IResource resource, ResourceJournalEntry entry, bool retain);
+    ResourceJournalPage QueryJournal(IResource resource, ResourceJournalQuery query);
+    void RemoveJournal(IResource resource);
+}
+
+/// <summary>
+/// Bounded in-memory implementation for volatile stores and tests. Persistent
+/// stores can implement <see cref="IResourceJournalStore"/> with their own
+/// transactional backend while preserving the same protocol contract.
+/// </summary>
+public sealed class ResourceJournalBuffer : IResourceJournalStore
+{
+    sealed class State
+    {
+        public ResourceCursor Head;
+        public ulong DiscardedThroughRevision;
+        public readonly LinkedList<ResourceJournalEntry> Entries = new();
+    }
+
+    sealed class ResourceReferenceComparer : IEqualityComparer<IResource>
+    {
+        public bool Equals(IResource x, IResource y) => ReferenceEquals(x, y);
+        public int GetHashCode(IResource obj) => RuntimeHelpers.GetHashCode(obj);
+    }
+
+    readonly object sync = new();
+    readonly Dictionary<IResource, State> states =
+        new(new ResourceReferenceComparer());
+    readonly int maximumEntriesPerResource;
+
+    public ResourceJournalBuffer(int maximumEntriesPerResource = 10000)
+    {
+        if (maximumEntriesPerResource < 1)
+            throw new ArgumentOutOfRangeException(nameof(maximumEntriesPerResource));
+        this.maximumEntriesPerResource = maximumEntriesPerResource;
+    }
+
+    public ResourceCursor OpenJournal(
+        IResource resource,
+        string resourceKey,
+        ResourceCursor proposedCursor)
+    {
+        if (resource == null) throw new ArgumentNullException(nameof(resource));
+        lock (sync)
+        {
+            if (states.TryGetValue(resource, out var existing))
+                return existing.Head;
+
+            var generation = proposedCursor.Generation == Guid.Empty
+                ? Guid.NewGuid()
+                : proposedCursor.Generation;
+            var cursor = new ResourceCursor(generation, proposedCursor.Revision);
+            states.Add(resource, new State { Head = cursor });
+            return cursor;
+        }
+    }
+
+    public bool AppendJournalEntry(IResource resource, ResourceJournalEntry entry, bool retain)
+    {
+        if (resource == null) throw new ArgumentNullException(nameof(resource));
+        if (entry == null) throw new ArgumentNullException(nameof(entry));
+
+        lock (sync)
+        {
+            if (!states.TryGetValue(resource, out var state))
+            {
+                state = new State { Head = new ResourceCursor(entry.Cursor.Generation, 0) };
+                states.Add(resource, state);
+            }
+
+            if (state.Head.Generation != entry.Cursor.Generation ||
+                entry.Cursor.Revision <= state.Head.Revision)
+                return false;
+
+            state.Head = entry.Cursor;
+            if (retain)
+                state.Entries.AddLast(entry);
+
+            while (state.Entries.Count > maximumEntriesPerResource)
+            {
+                state.DiscardedThroughRevision = Math.Max(
+                    state.DiscardedThroughRevision,
+                    state.Entries.First.Value.Cursor.Revision);
+                state.Entries.RemoveFirst();
+            }
+
+            return true;
+        }
+    }
+
+    public ResourceJournalPage QueryJournal(IResource resource, ResourceJournalQuery query)
+    {
+        if (resource == null) throw new ArgumentNullException(nameof(resource));
+        query ??= new ResourceJournalQuery();
+        var limit = Math.Max(1, Math.Min(query.Limit, 10000));
+
+        lock (sync)
+        {
+            var proposed = new ResourceCursor(Guid.NewGuid(), 0);
+            if (!states.TryGetValue(resource, out var state))
+            {
+                state = new State { Head = proposed };
+                states.Add(resource, state);
+            }
+
+            var after = query.After;
+            var generationMismatch = after.Generation != Guid.Empty &&
+                                     after.Generation != state.Head.Generation;
+            var expired = generationMismatch ||
+                          (!generationMismatch &&
+                           after.Revision < state.DiscardedThroughRevision);
+
+            if (generationMismatch)
+                after = new ResourceCursor(state.Head.Generation, 0);
+
+            IEnumerable<ResourceJournalEntry> filtered = state.Entries
+                .Where(entry => entry.Cursor.Revision > after.Revision);
+
+            if (query.ThroughRevision.HasValue)
+                filtered = filtered.Where(entry => entry.Cursor.Revision <= query.ThroughRevision.Value);
+            if (query.FromTime.HasValue)
+                filtered = filtered.Where(entry => entry.RecordedAt >= query.FromTime.Value.ToUniversalTime());
+            if (query.ToTime.HasValue)
+                filtered = filtered.Where(entry => entry.RecordedAt <= query.ToTime.Value.ToUniversalTime());
+            if (query.Kind.HasValue)
+                filtered = filtered.Where(entry => entry.Kind == query.Kind.Value);
+            if (query.MemberIndex.HasValue)
+                filtered = filtered.Where(entry => entry.MemberIndex == query.MemberIndex.Value);
+
+            var selected = filtered.Take(limit + 1).ToArray();
+            var hasMore = selected.Length > limit;
+            var entries = hasMore ? selected.Take(limit).ToArray() : selected;
+            var next = entries.Length == 0 ? after : entries[entries.Length - 1].Cursor;
+            var oldest = state.Entries.First?.Value.Cursor ?? state.Head;
+
+            return new ResourceJournalPage(
+                oldest,
+                state.Head,
+                next,
+                expired,
+                hasMore,
+                entries);
+        }
+    }
+
+    public void RemoveJournal(IResource resource)
+    {
+        if (resource == null) return;
+        lock (sync) states.Remove(resource);
+    }
+}

Libraries/Esiur/Resource/Warehouse.cs

@@ -1036,7 +1036,14 @@ public class Warehouse
 
         var resourceId = (uint)Interlocked.Increment(ref _resourceCounter);
 
-        resource.Instance = new Instance(this, resourceId, instanceName, resource, store, resourceContext?.Age ?? 0);
+        resource.Instance = new Instance(
+            this,
+            resourceId,
+            instanceName,
+            resource,
+            store,
+            resourceContext?.Age ?? 0,
+            string.Join("/", location));
 
         resource.Instance.Managers.AddRange(resourceManagers);
 
@@ -1310,6 +1317,48 @@ public class Warehouse
         }
     }
 
+    /// <summary>
+    /// Registers a definition supplied by an <see cref="IDynamicResource"/>
+    /// without replacing its stable identifier. Dynamic definitions are not
+    /// backed by a CLR <see cref="LocalTypeDef"/>, so they cannot use the
+    /// incremental local registration path, but remote peers must still be
+    /// able to resolve them through TypeDefById.
+    /// </summary>
+    internal void RegisterDynamicTypeDef(TypeDef typeDef)
+    {
+        if (typeDef == null)
+            throw new ArgumentNullException(nameof(typeDef));
+
+        lock (_typeDefsLock)
+        {
+            // A remote definition keeps the producer's id for wire lookups, but
+            // TryRegisterRemoteTypeDef gives it a Warehouse-local id because remote
+            // resource/record/enum id spaces can overlap. Dynamic proxy instances
+            // must reuse that local registration instead of indexing by the wire id.
+            var registrationId = typeDef is RemoteTypeDef remoteTypeDef
+                && remoteTypeDef.LocalTypeDefId != 0
+                    ? remoteTypeDef.LocalTypeDefId
+                    : typeDef.Id;
+            var existing = _localTypeDefs[registrationId];
+            if (existing == null)
+            {
+                _localTypeDefs[registrationId] = typeDef;
+                return;
+            }
+
+            if (ReferenceEquals(existing, typeDef) ||
+                (existing.Kind == typeDef.Kind &&
+                 existing.Version == typeDef.Version &&
+                 string.Equals(existing.Name, typeDef.Name, StringComparison.Ordinal)))
+            {
+                return;
+            }
+
+            throw new InvalidOperationException(
+                $"Dynamic TypeDef id {registrationId} is already registered by '{existing.Name}', not '{typeDef.Name}'.");
+        }
+    }
+
     internal KeyList<TypeDefKind, KeyList<string , Type>> GetProxyTypesByDomain(string domain)
     {
         return _proxyTypeDefs[domain];
@@ -1317,6 +1366,7 @@ public class Warehouse
 
     public bool TryRegisterRemoteTypeDef(string domain, RemoteTypeDef typeDef)
     {
+        domain = string.IsNullOrWhiteSpace(domain) ? "anonymous" : domain;
         lock (_typeDefsLock)
         {
             if (!_remoteTypeDefs.ContainsKey(domain))

Libraries/Esiur/Stores/MemoryStore.cs

@@ -10,7 +10,7 @@ using Esiur.Data.Types;
  
 namespace Esiur.Stores;
 
-public class MemoryStore : IStore
+public class MemoryStore : IStore, IResourceJournalStore
 {
     public Instance Instance { get; set; }
 
@@ -18,6 +18,31 @@ public class MemoryStore : IStore
 
 
     KeyList<uint, IResource> resources = new KeyList<uint, IResource>();
+    readonly IResourceJournalStore journal;
+
+    public MemoryStore()
+        : this(new ResourceJournalBuffer())
+    {
+    }
+
+    public MemoryStore(IResourceJournalStore journal)
+    {
+        this.journal = journal ?? throw new ArgumentNullException(nameof(journal));
+    }
+
+    public ResourceCursor OpenJournal(
+        IResource resource,
+        string resourceKey,
+        ResourceCursor proposedCursor) =>
+        journal.OpenJournal(resource, resourceKey, proposedCursor);
+
+    public bool AppendJournalEntry(IResource resource, ResourceJournalEntry entry, bool retain) =>
+        journal.AppendJournalEntry(resource, entry, retain);
+
+    public ResourceJournalPage QueryJournal(IResource resource, ResourceJournalQuery query) =>
+        journal.QueryJournal(resource, query);
+
+    public void RemoveJournal(IResource resource) => journal.RemoveJournal(resource);
 
     public void Destroy()
     {
@@ -161,6 +186,7 @@ public class MemoryStore : IStore
     AsyncReply<bool> IStore.Remove(IResource resource)
     {
         resources.Remove(resource.Instance.Id);
+        journal.RemoveJournal(resource);
         return AsyncReply.FromResult(true);
     }
 

Libraries/Esiur/Stores/TemporaryStore.cs

@@ -9,13 +9,28 @@ using Esiur.Data;
 using Esiur.Data.Types;
 
 namespace Esiur.Stores;
-public class TemporaryStore : IStore
+public class TemporaryStore : IStore, IResourceJournalStore
 {
     public Instance Instance { get; set; }
 
     public event DestroyedEvent OnDestroy;
     
     Dictionary<uint, WeakReference> resources = new Dictionary<uint, WeakReference>();
+    readonly ResourceJournalBuffer journal = new();
+
+    public ResourceCursor OpenJournal(
+        IResource resource,
+        string resourceKey,
+        ResourceCursor proposedCursor) =>
+        journal.OpenJournal(resource, resourceKey, proposedCursor);
+
+    public bool AppendJournalEntry(IResource resource, ResourceJournalEntry entry, bool retain) =>
+        journal.AppendJournalEntry(resource, entry, retain);
+
+    public ResourceJournalPage QueryJournal(IResource resource, ResourceJournalQuery query) =>
+        journal.QueryJournal(resource, query);
+
+    public void RemoveJournal(IResource resource) => journal.RemoveJournal(resource);
 
     public void Destroy()
     {
@@ -90,6 +105,7 @@ public class TemporaryStore : IStore
     AsyncReply<bool> IStore.Remove(IResource resource)
     {
         resources.Remove(resource.Instance.Id);
+        journal.RemoveJournal(resource);
         return new AsyncReply<bool>(true);
     }
 

README.md

@@ -173,15 +173,12 @@ The `ep://` URL identifies the logical connection and resource path;
 `WebSocketUri` identifies the transport endpoint. Esiur automatically requests
 the case-sensitive `EP` WebSocket subprotocol.
 
-For native TCP, omit `WebSocketUri` and include the EP port in the logical URL:
+For native TCP, omit `WebSocketUri`. Esiur uses port `51018` when the logical
+URL omits a port:
 
 ```csharp
-var epPort = ushort.Parse(
-    Environment.GetEnvironmentVariable("ESIUR_PORT")
-    ?? throw new InvalidOperationException("Set ESIUR_PORT."));
-
 dynamic counter = await client.Get<IResource>(
-    $"ep://localhost:{epPort}/sys/counter");
+    "ep://localhost/sys/counter");
 ```
 
 ## Standalone hosting
@@ -195,16 +192,12 @@ using Esiur.Protocol;
 using Esiur.Resource;
 using Esiur.Stores;
 
-var epPort = ushort.Parse(
-    Environment.GetEnvironmentVariable("ESIUR_PORT")
-    ?? throw new InvalidOperationException("Set ESIUR_PORT."));
 var warehouse = new Warehouse();
 
 await warehouse.Put("sys", new MemoryStore());
 await warehouse.Put("sys/counter", new CounterResource());
 await warehouse.Put("sys/server", new EpServer
 {
-    Port = epPort,
     AllowUnauthorizedAccess = true, // Development only.
 });
 
@@ -224,6 +217,50 @@ Use a separate `Warehouse` for each isolated server or client runtime. Avoid
 relying on the static default Warehouse in applications that host more than one
 Esiur environment.
 
+## Resource revisions and historical events
+
+Esiur 3 uses one ordered cursor for every observable change made by a resource:
+
+```text
+(generation UUID, resource-wide revision)
+```
+
+Property modifications and event occurrences share this sequence. Notifications
+also carry their original UTC recording time. A new generation means that the
+producer cannot continue the previous sequence, so consumers must replace their
+snapshot instead of comparing revisions from the two generations.
+
+Mark an event with `[Historical]` when disconnected consumers must be able to
+replay it. Ordinary events remain live-only and do not grow the retained journal.
+
+```csharp
+[Export, Historical]
+public event ResourceEventHandler<ReadingRecord>? Reading;
+
+var checkpoint = remote.Instance.Cursor;
+await remote.OnFromAsync("Reading", checkpoint, value =>
+{
+    var reading = (ReadingRecord)value;
+    // Persist the reading, then save the cursor received through
+    // remote.Instance.EventOccurred.
+});
+```
+
+`EpResource.QueryJournal(...)` supports bounded queries by cursor, time, entry
+kind, and member. `OnFromAsync(...)` atomically replays retained occurrences and
+then continues with live delivery. Each consumer owns its checkpoint; the source
+does not delete an event merely because one client received it. Reconnect uses
+the per-event checkpoint automatically, and returns `CursorExpired` if retention
+can no longer satisfy the requested position.
+
+The resource's owning store controls retention through `IResourceJournalStore`.
+The bundled memory, temporary, and current EntityCore adapters use a bounded
+10,000-entry process-local journal per resource. A deployment requiring replay
+across producer restarts must use a durable implementation of that interface.
+
+This changes the EP v3 attach, reattach, subscribe, notification, and journal
+request shapes. All communicating v3 peers must be upgraded together.
+
 ## Authentication and encryption
 
 Anonymous access is opt-in. Production services should omit `AllowAnonymous`,
@@ -350,8 +387,8 @@ EP is self-describing, so clients can work dynamically or generate strongly
 typed models. Install the v3 CLI as a .NET tool:
 
 ```shell
-dotnet tool install --global Esiur.CLI --version 3.0.0
-esiur get-template "ep://localhost:${ESIUR_PORT}/sys/counter" --dir Generated
+dotnet tool install --global Esiur.CLI --version 3.1.0
+esiur get-template "ep://localhost/sys/counter" --dir Generated
 ```
 
 Use `--async-setters` to generate asynchronous property setters. The CLI also

Stores/Esiur.Stores.EntityCore/EntityStore.cs

@@ -37,7 +37,7 @@ using System.Collections;
 using Esiur.Data.Types;
 
 namespace Esiur.Stores.EntityCore;
-public class EntityStore : IStore
+public class EntityStore : IStore, IResourceJournalStore
 {
     public Instance Instance { get; set; }
 
@@ -50,6 +50,21 @@ public class EntityStore : IStore
 
     Dictionary<Type, Dictionary<object, WeakReference>> DB = new Dictionary<Type, Dictionary<object, WeakReference>>();
     object DBLock = new object();
+    readonly ResourceJournalBuffer journal = new();
+
+    public ResourceCursor OpenJournal(
+        IResource resource,
+        string resourceKey,
+        ResourceCursor proposedCursor) =>
+        journal.OpenJournal(resource, resourceKey, proposedCursor);
+
+    public bool AppendJournalEntry(IResource resource, ResourceJournalEntry entry, bool retain) =>
+        journal.AppendJournalEntry(resource, entry, retain);
+
+    public ResourceJournalPage QueryJournal(IResource resource, ResourceJournalQuery query) =>
+        journal.QueryJournal(resource, query);
+
+    public void RemoveJournal(IResource resource) => journal.RemoveJournal(resource);
 
     Dictionary<string, EntityTypeInfo> TypesByName = new Dictionary<string, EntityTypeInfo>();
     internal Dictionary<Type, EntityTypeInfo> TypesByType = new Dictionary<Type, EntityTypeInfo>();
@@ -293,6 +308,7 @@ public class EntityStore : IStore
             if (DB[type].ContainsKey(eid))
             {
                 DB[type].Remove(eid);
+                journal.RemoveJournal(resource);
                 return new AsyncReply<bool>(true);
             }
         }

Tests/Esiur.CLI.Tests/ConfigurationTests.cs

@@ -8,6 +8,7 @@ namespace Esiur.CLI.Tests;
 public sealed class ConfigurationTests
 {
     [Theory]
+    [InlineData("ep://localhost", "ep://localhost")]
     [InlineData("ep://localhost:65535", "ep://localhost:65535")]
     [InlineData("ep://example.test:9000/sys/service", "ep://example.test:9000")]
     public void EndpointParserExtractsConnectionEndpoint(string value, string expected) =>
@@ -15,7 +16,7 @@ public sealed class ConfigurationTests
 
     [Theory]
     [InlineData("http://localhost")]
-    [InlineData("ep://localhost")]
+    [InlineData("ep://localhost:0")]
     [InlineData("ep:///missing-host")]
     [InlineData("not-an-endpoint")]
     public void EndpointParserRejectsInvalidEndpoints(string value) =>

Tests/RPC/Client/Model/Esiur/Esiur.Tests.RPC.EsiurServer.Service.g.cs

@@ -183,12 +183,13 @@ namespace Esiur.Tests.RPC.EsiurServer
             get => (object)_properties[1];
             set => SetResourceProperty(1, value);
         }
-        protected override void _EmitEventByIndex(byte index, object args)
+        protected override void _EmitEventByIndex(byte index, object args, ResourceCursor cursor, DateTime recordedAt)
         {
             switch (index)
             {
                 case 0: MessageUpdated?.Invoke((byte[])args); break;
             }
+            base._EmitEventByIndex(index, args, cursor, recordedAt);
         }
         [Export] public event ResourceEventHandler<byte[]> MessageUpdated;
 

Tests/Unit/EpPortTests.cs

@@ -6,17 +6,19 @@ namespace Esiur.Tests.Unit;
 public sealed class EpPortTests
 {
     [Fact]
-    public void ServerDoesNotAssignAProtocolPort()
-        => Assert.Equal(0, new EpServer().Port);
+    public void ServerUsesTheProtocolDefaultPort()
+        => Assert.Equal(EpProtocol.DefaultPort, new EpServer().Port);
 
     [Fact]
-    public async Task ClientEndpointWithoutPortIsRejected()
+    public void ClientEndpointWithoutPortUsesTheProtocolDefault()
     {
-        var warehouse = new Warehouse();
-
-        var exception = await Assert.ThrowsAsync<FormatException>(async () =>
-            await warehouse.Get<EpConnection>("ep://localhost/sys/resource"));
-
-        Assert.Contains("explicit port", exception.Message, StringComparison.OrdinalIgnoreCase);
+        var endpoint = new Uri("ep://localhost/sys/resource");
+        Assert.Equal(EpProtocol.DefaultPort, EpConnection.ResolveEndpointPort(endpoint));
     }
+
+    [Fact]
+    public void ExplicitClientPortStillOverridesTheProtocolDefault()
+        => Assert.Equal(
+            12345,
+            EpConnection.ResolveEndpointPort(new Uri("ep://localhost:12345/sys/resource")));
 }

Tests/Unit/Integration/BeaconResource.cs

@@ -9,7 +9,9 @@ public partial class BeaconResource
 
     // No [AutoDelivery]: subscribable by default — requires an explicit
     // Subscribe request before occurrences flow to a given connection.
-    [Export] public event ResourceEventHandler<string>? Ping;
+    [Export]
+    [Historical]
+    public event ResourceEventHandler<string>? Ping;
 
     // Opts out via [AutoDelivery]: flows to every attached connection
     // unconditionally.

Tests/Unit/Integration/EventSubscriptionIntegrationTests.cs

@@ -6,6 +6,110 @@ namespace Esiur.Tests.Unit.Integration;
 [Collection("Integration")]
 public class EventSubscriptionIntegrationTests
 {
+    [Fact]
+    public async Task PropertyAndEventNotifications_ShareOneOrderedResourceRevision()
+    {
+        await using var cluster = await StartClusterAsync(out var getBeacon).WaitAsync(TimeSpan.FromSeconds(10));
+        var remote = await GetRemote(cluster);
+        var beacon = getBeacon();
+        var propertyRevisions = new List<ResourceCursor>();
+        var eventRevisions = new List<ResourceCursor>();
+
+        remote.Instance.PropertyModified += info => propertyRevisions.Add(info.Cursor);
+        remote.Instance.EventOccurred += info => eventRevisions.Add(info.Cursor);
+        await remote.OnAsync("Ping", _ => { });
+
+        beacon.Fire("ping", "ordered");
+        await WaitUntilAsync(
+            () => propertyRevisions.Count == 1 && eventRevisions.Count == 1,
+            TimeSpan.FromSeconds(3));
+
+        Assert.Equal(propertyRevisions[0].Generation, eventRevisions[0].Generation);
+        Assert.Equal(propertyRevisions[0].Revision + 1, eventRevisions[0].Revision);
+        Assert.Equal(eventRevisions[0], remote.Instance.Cursor);
+    }
+
+    [Fact]
+    public async Task QueryJournal_ReturnsHistoricalEventAfterCursor()
+    {
+        await using var cluster = await StartClusterAsync(out var getBeacon).WaitAsync(TimeSpan.FromSeconds(10));
+        var remote = await GetRemote(cluster);
+        var beacon = getBeacon();
+        var attachedAt = remote.Instance.Cursor;
+        var ping = remote.Instance.Definition.GetEventDefByName("Ping");
+
+        beacon.Fire("ping", "retained");
+
+        var page = await remote.QueryJournal(new ResourceJournalQuery
+        {
+            After = attachedAt,
+            Kind = ResourceJournalEntryKind.EventOccurred,
+            MemberIndex = ping.Index,
+        });
+
+        var entry = Assert.Single(page.Entries);
+        Assert.False(page.CursorExpired);
+        Assert.Equal(ResourceJournalEntryKind.EventOccurred, entry.Kind);
+        Assert.Equal(ping.Index, entry.MemberIndex);
+        Assert.Equal("retained", entry.Value);
+        Assert.True(entry.Cursor.Revision > attachedAt.Revision);
+    }
+
+    [Fact]
+    public async Task HistoricalSubscription_ReplaysOccurrenceMissedDuringReconnect()
+    {
+        await using var cluster = await StartClusterAsync(out var getBeacon).WaitAsync(TimeSpan.FromSeconds(10));
+        cluster.Connection.AutoReconnect = true;
+        cluster.Connection.ReconnectInterval = 1;
+        var remote = await GetRemote(cluster);
+        var beacon = getBeacon();
+        var received = new List<string>();
+
+        await remote.OnAsync("Ping", value => received.Add((string)value));
+        beacon.Fire("ping", "before");
+        await WaitUntilAsync(() => received.Count == 1, TimeSpan.FromSeconds(3));
+
+        foreach (var serverConnection in cluster.Server.Connections.ToArray())
+            serverConnection.Destroy();
+
+        await WaitUntilAsync(() => !cluster.Connection.IsConnected, TimeSpan.FromSeconds(3));
+        beacon.Fire("ping", "while-offline");
+        await WaitUntilAsync(() => cluster.Connection.IsConnected, TimeSpan.FromSeconds(5));
+        await WaitUntilAsync(() => received.Count == 2, TimeSpan.FromSeconds(5));
+
+        Assert.Equal(new[] { "before", "while-offline" }, received);
+    }
+
+    [Fact]
+    public async Task HistoricalSubscription_ReplaysEveryPageBeforeLiveDelivery()
+    {
+        const int occurrenceCount = 10_001;
+        BeaconResource? beacon = null;
+        await using var cluster = await IntegrationCluster.StartAsync(
+            async warehouse =>
+            {
+                beacon = new BeaconResource();
+                await warehouse.Put("sys/beacon", beacon);
+            },
+            resourceJournalCapacity: occurrenceCount + 1).WaitAsync(TimeSpan.FromSeconds(10));
+
+        for (var index = 0; index < occurrenceCount; index++)
+            beacon!.Fire("ping", index.ToString());
+
+        var remote = await GetRemote(cluster);
+        var received = new List<string>(occurrenceCount);
+        await remote.OnFromAsync(
+            "Ping",
+            new ResourceCursor(remote.Instance.Generation, 0),
+            value => received.Add((string)value));
+
+        await WaitUntilAsync(
+            () => received.Count == occurrenceCount,
+            TimeSpan.FromSeconds(10));
+        Assert.Equal("0", received[0]);
+        Assert.Equal((occurrenceCount - 1).ToString(), received[^1]);
+    }
+
     [Fact]
     public async Task On_DeliversAutoDeliveredEventWithNoSubscribeNeeded()
     {
@@ -60,6 +164,21 @@ public class EventSubscriptionIntegrationTests
         Assert.Equal(new[] { "x", "y" }, b); // neither received "z"
     }
 
+    [Fact]
+    public async Task OnAsync_CompletesAfterWireSubscriptionIsReady()
+    {
+        await using var cluster = await StartClusterAsync(out var getBeacon).WaitAsync(TimeSpan.FromSeconds(10));
+        var remote = await GetRemote(cluster);
+        var beacon = getBeacon();
+        var received = new List<string>();
+
+        await remote.OnAsync("Ping", value => received.Add((string)value));
+        beacon.Fire("ping", "immediate");
+
+        await WaitUntilAsync(() => received.Count == 1, TimeSpan.FromSeconds(3));
+        Assert.Equal(new[] { "immediate" }, received);
+    }
+
     [Fact]
     public async Task NativePlusEquals_AutoSubscribesAndUnsubscribes()
     {

Tests/Unit/Integration/IntegrationHarness.cs

@@ -205,7 +205,11 @@ internal sealed class IntegrationCluster : IAsyncDisposable
         bool mismatchedSessionKeys = false,
         bool requireKeyRotation = false,
         bool allowAuthentication = true,
-        bool registerServerAuthenticationProvider = true)
+        bool registerServerAuthenticationProvider = true,
+        bool anonymous = false,
+        int resourceJournalCapacity = 10000,
+        Action<EpServer> serverCreated = null,
+        Func<Warehouse, Task> populateClient = null)
     {
         var port = NextAvailablePort();
 
@@ -217,10 +221,13 @@ internal sealed class IntegrationCluster : IAsyncDisposable
         if (encrypted || requireEncryption)
             serverWh.RegisterEncryptionProvider(new AesEncryptionProvider());
 
-        await serverWh.Put("sys", new MemoryStore());
+        await serverWh.Put(
+            "sys",
+            new MemoryStore(new ResourceJournalBuffer(resourceJournalCapacity)));
         var server = await serverWh.Put("sys/server", new EpServer
         {
             Port = (ushort)port,
+            AllowUnauthorizedAccess = anonymous,
             AllowedAuthenticationProviders = allowAuthentication
                 ? new[]
                 {
@@ -234,6 +241,7 @@ internal sealed class IntegrationCluster : IAsyncDisposable
                 : Array.Empty<string>(),
             RequireEncryption = requireEncryption,
         });
+        serverCreated?.Invoke(server);
 
         await populate(serverWh);
 
@@ -246,6 +254,8 @@ internal sealed class IntegrationCluster : IAsyncDisposable
                 mismatchedSessionKeys ? (byte)0x80 : (byte)0,
                 requireKeyRotation)
             : new TestClientAuthProvider());
+        if (populateClient is not null)
+            await populateClient(cluster.ClientWarehouse);
         if (encrypted)
             cluster.ClientWarehouse.RegisterEncryptionProvider(new AesEncryptionProvider());
 
@@ -255,12 +265,16 @@ internal sealed class IntegrationCluster : IAsyncDisposable
                 $"ep://localhost:{port}",
                 new EpConnectionContext
                 {
-                    AuthenticationMode = AuthenticationMode.InitializerIdentity,
-                    Identity = "tester",
+                    AuthenticationMode = anonymous
+                        ? AuthenticationMode.None
+                        : AuthenticationMode.InitializerIdentity,
+                    Identity = anonymous ? null : "tester",
                     AuthenticationProtocol = oneStepAuthentication
                         ? "one-step"
-                        : PasswordAuthenticationProvider.ProtocolName,
-                    Domain = "test",
+                        : anonymous
+                            ? null
+                            : PasswordAuthenticationProvider.ProtocolName,
+                    Domain = anonymous ? null : "test",
                     EncryptionMode = encrypted
                         ? encryptionMode
                         : EncryptionMode.None,

Tests/Unit/Integration/SessionHeadersIntegrationTests.cs

@@ -3,13 +3,77 @@ namespace Esiur.Tests.Unit.Integration;
 using Esiur.Data;
 using Esiur.Net.Sockets;
 using Esiur.Protocol;
+using Esiur.Resource;
 using Esiur.Security.Authority.Providers;
 using Esiur.Security.Cryptography;
+using Esiur.Stores;
 using System.Net;
 
 [Collection("Integration")]
 public class SessionHeadersIntegrationTests
 {
+    [Fact]
+    public async Task AcceptedConnection_RaisesReadyAndDisconnectedLifecycleEvents()
+    {
+        var ready = new TaskCompletionSource<EpConnection>(
+            TaskCreationOptions.RunContinuationsAsynchronously);
+        var disconnected = new TaskCompletionSource<EpConnection>(
+            TaskCreationOptions.RunContinuationsAsynchronously);
+
+        await using var cluster = await IntegrationCluster
+            .StartAsync(
+                _ => Task.CompletedTask,
+                serverCreated: server =>
+                {
+                    server.ConnectionReady += connection => ready.TrySetResult(connection);
+                    server.ConnectionDisconnected += connection => disconnected.TrySetResult(connection);
+                })
+            .WaitAsync(TimeSpan.FromSeconds(10));
+
+        var accepted = await ready.Task.WaitAsync(TimeSpan.FromSeconds(5));
+        Assert.True(accepted.Session.Authenticated);
+        Assert.Equal("tester", accepted.Session.RemoteIdentity);
+
+        accepted.NetworkClose(accepted.Socket);
+        Assert.Same(
+            accepted,
+            await disconnected.Task.WaitAsync(TimeSpan.FromSeconds(5)));
+    }
+
+    [Fact]
+    public async Task AcceptedConnection_CanFetchInitiatorResourceBidirectionally()
+    {
+        var fetched = new TaskCompletionSource<IResource>(
+            TaskCreationOptions.RunContinuationsAsynchronously);
+
+        await using var cluster = await IntegrationCluster
+            .StartAsync(
+                _ => Task.CompletedTask,
+                serverCreated: server => server.ConnectionReady += connection =>
+                    _ = Task.Run(async () =>
+                    {
+                        try
+                        {
+                            fetched.TrySetResult(await connection.Get("client/exported"));
+                        }
+                        catch (Exception exception)
+                        {
+                            fetched.TrySetException(exception);
+                        }
+                    }),
+                populateClient: async warehouse =>
+                {
+                    await warehouse.Put("client", new MemoryStore());
+                    await warehouse.Put("client/exported", new Node { Id = 818 });
+                })
+            .WaitAsync(TimeSpan.FromSeconds(10));
+
+        var proxy = Assert.IsType<EpResource>(
+            await fetched.Task.WaitAsync(TimeSpan.FromSeconds(5)));
+        dynamic exported = proxy;
+        Assert.Equal(818, Convert.ToInt32(exported.Id));
+    }
+
     [Fact]
     public async Task AuthenticatedHandshake_StoresTypedHeadersWithoutAuthenticationData()
     {
@@ -234,6 +298,36 @@ public class SessionHeadersIntegrationTests
         Assert.Equal(203, Convert.ToInt32(result));
     }
 
+    [Fact]
+    public async Task AnonymousWebSocketTransport_AssignsSchemaDomain()
+    {
+        await using var cluster = await IntegrationCluster
+            .StartAsync(
+                async warehouse =>
+                {
+                    await warehouse.Put("sys/websocket-anonymous", new EncryptedEchoResource());
+                },
+                useWebSocket: true,
+                anonymous: true)
+            .WaitAsync(TimeSpan.FromSeconds(10));
+
+        var remote = (EpResource)await Task.Run(async () =>
+            await cluster.Connection.Get("sys/websocket-anonymous"))
+            .WaitAsync(TimeSpan.FromSeconds(10));
+        var function = remote.Instance.Definition
+            .GetFunctionDefByName(nameof(EncryptedEchoResource.Echo));
+        var result = await remote._Invoke(
+            function.Index,
+            new Map<byte, object>
+            {
+                [0] = 42,
+            });
+
+        Assert.Equal(42, Convert.ToInt32(result));
+        Assert.False(string.IsNullOrWhiteSpace(
+            Assert.Single(cluster.Server.Connections).RemoteDomain));
+    }
+
     [Fact]
     public async Task WrongAuthenticatedSessionKey_FailsPromptlyDuringKeyConfirmation()
     {

Tests/Unit/RuntimeCasterRecordTests.cs

@@ -0,0 +1,44 @@
+using Esiur.Data;
+using Esiur.Resource;
+
+namespace Esiur.Tests.Unit;
+
+public sealed class RuntimeCasterRecordTests
+{
+    [Fact]
+    public void DynamicRecordMaterializesAsDeclaredRecordType()
+    {
+        var warehouse = new Warehouse();
+        var nestedDefinition = warehouse.GetLocalTypeDefByType(typeof(NestedRecord));
+        var targetDefinition = warehouse.GetLocalTypeDefByType(typeof(TargetRecord));
+        var nested = new Esiur.Data.Record(nestedDefinition)
+        {
+            [nameof(NestedRecord.Name)] = "edge-1",
+        };
+        var source = new Esiur.Data.Record(targetDefinition)
+        {
+            [nameof(TargetRecord.Enabled)] = true,
+            [nameof(TargetRecord.Count)] = (short)7,
+            [nameof(TargetRecord.Nested)] = nested,
+        };
+
+        var converted = Assert.IsType<TargetRecord>(
+            RuntimeCaster.Cast(source, typeof(TargetRecord)));
+
+        Assert.True(converted.Enabled);
+        Assert.Equal(7, converted.Count);
+        Assert.Equal("edge-1", converted.Nested.Name);
+    }
+
+    private sealed class TargetRecord : IRecord
+    {
+        public bool Enabled { get; set; }
+        public int Count { get; set; }
+        public NestedRecord Nested { get; set; } = new();
+    }
+
+    private sealed class NestedRecord : IRecord
+    {
+        public string Name { get; set; } = string.Empty;
+    }
+}

Tools/Esiur.CLI/Configuration/ConfigurationResolver.cs

@@ -63,8 +63,8 @@ public static class ConfigurationResolver
     static readonly string[] ValidSchemes = ["ep", "eps", "ws", "wss"];
 
     /// <summary>
-    /// Accepts <c>ep(s)://host:port</c> (a bare Esiur endpoint, connects at the
-    /// WebSocket root) as well as <c>ws(s)://host:port/path</c> (for hosts like
+    /// Accepts <c>ep(s)://host[:port]</c> (a bare Esiur endpoint, connects at the
+    /// WebSocket root) as well as <c>ws(s)://host[:port]/path</c> (for hosts like
     /// ASP.NET Core's <c>MapEsiur("/esiur")</c> that mount the WebSocket route
     /// somewhere other than root) — see <see cref="EndpointParser"/> for how
     /// the two forms are dialed.
@@ -75,37 +75,12 @@ public static class ConfigurationResolver
             || !ValidSchemes.Contains(uri.Scheme, StringComparer.OrdinalIgnoreCase)
             || string.IsNullOrWhiteSpace(uri.Host)
             || !string.IsNullOrEmpty(uri.UserInfo)
-            || !HasExplicitPort(endpoint))
+            || uri.Port == 0
+            || uri.Port > ushort.MaxValue)
             throw new CliException(
-                $"Endpoint \"{endpoint}\" is not a valid ep:// or ws:// endpoint with an explicit port.",
+                $"Endpoint \"{endpoint}\" is not a valid ep:// or ws:// endpoint.",
                 ExitCodes.InvalidArguments);
     }
-
-    static bool HasExplicitPort(string endpoint)
-    {
-        var schemeEnd = endpoint.IndexOf("://", StringComparison.Ordinal);
-        if (schemeEnd < 0)
-            return false;
-
-        var authorityStart = schemeEnd + 3;
-        var authorityEnd = endpoint.IndexOfAny(['/', '?', '#'], authorityStart);
-        if (authorityEnd < 0)
-            authorityEnd = endpoint.Length;
-
-        var authority = endpoint[authorityStart..authorityEnd];
-        var at = authority.LastIndexOf('@');
-        if (at >= 0)
-            authority = authority[(at + 1)..];
-
-        var colon = authority.StartsWith('[')
-            ? authority.IndexOf(']') + 1
-            : authority.LastIndexOf(':');
-        return colon > 0
-            && colon < authority.Length - 1
-            && authority[colon] == ':'
-            && ushort.TryParse(authority[(colon + 1)..], out var port)
-            && port > 0;
-    }
 }
 
 public static class DurationParser

Tools/Esiur.CLI/README.md

@@ -19,13 +19,13 @@ Runtime-specific publishes are configured as self-contained, single-file, and no
 Create and verify a password-authenticated profile:
 
 ```console
-esiur login production "ep://host:${ESIUR_PORT}" --provider password --identity ahmed
+esiur login production "ep://host" --provider password --identity ahmed
 ```
 
 The password prompt does not echo input. For automation, supply it on standard input:
 
 ```console
-printf '%s' "$ESIUR_PASSWORD" | esiur login production "ep://host:${ESIUR_PORT}" \
+printf '%s' "$ESIUR_PASSWORD" | esiur login production "ep://host" \
   --provider password --identity ahmed --password-stdin
 ```
 
@@ -86,7 +86,7 @@ Every operational command accepts a saved profile or a temporary endpoint:
 
 ```console
 esiur --profile production describe sys/service
-esiur --endpoint "ep://host:${ESIUR_PORT}" query sys --output json
+esiur --endpoint "ep://host" query sys --output json
 esiur get sys/service Name --timeout 30s
 ```