diff --git a/src/A2A.Client.Abstractions/A2A.Client.Abstractions.csproj b/src/A2A.Client.Abstractions/A2A.Client.Abstractions.csproj
index 1b80a98..5d56956 100644
--- a/src/A2A.Client.Abstractions/A2A.Client.Abstractions.csproj
+++ b/src/A2A.Client.Abstractions/A2A.Client.Abstractions.csproj
@@ -5,7 +5,7 @@
     <ImplicitUsings>enable</ImplicitUsings>
     <Nullable>enable</Nullable>
 	<RootNamespace>A2A.Client</RootNamespace>
-    <VersionPrefix>0.14.0</VersionPrefix>
+    <VersionPrefix>0.15.0</VersionPrefix>
     <AssemblyVersion>$(VersionPrefix)</AssemblyVersion>
     <FileVersion>$(VersionPrefix)</FileVersion>
     <NeutralLanguage>en</NeutralLanguage>
diff --git a/src/A2A.Client.Transports.Grpc/A2A.Client.Transports.Grpc.csproj b/src/A2A.Client.Transports.Grpc/A2A.Client.Transports.Grpc.csproj
index 117452b..191cee4 100644
--- a/src/A2A.Client.Transports.Grpc/A2A.Client.Transports.Grpc.csproj
+++ b/src/A2A.Client.Transports.Grpc/A2A.Client.Transports.Grpc.csproj
@@ -5,7 +5,7 @@
     <ImplicitUsings>enable</ImplicitUsings>
     <Nullable>enable</Nullable>
 	<RootNamespace>A2A.Client.Transports</RootNamespace>
-    <VersionPrefix>0.14.0</VersionPrefix>
+    <VersionPrefix>0.15.0</VersionPrefix>
     <AssemblyVersion>$(VersionPrefix)</AssemblyVersion>
     <FileVersion>$(VersionPrefix)</FileVersion>
     <NeutralLanguage>en</NeutralLanguage>
diff --git a/src/A2A.Client.Transports.Http/A2A.Client.Transports.Http.csproj b/src/A2A.Client.Transports.Http/A2A.Client.Transports.Http.csproj
index 76efb4a..8589b5d 100644
--- a/src/A2A.Client.Transports.Http/A2A.Client.Transports.Http.csproj
+++ b/src/A2A.Client.Transports.Http/A2A.Client.Transports.Http.csproj
@@ -5,7 +5,7 @@
     <ImplicitUsings>enable</ImplicitUsings>
     <Nullable>enable</Nullable>
 	<RootNamespace>A2A.Client.Transports</RootNamespace>
-    <VersionPrefix>0.14.0</VersionPrefix>
+    <VersionPrefix>0.15.0</VersionPrefix>
     <AssemblyVersion>$(VersionPrefix)</AssemblyVersion>
     <FileVersion>$(VersionPrefix)</FileVersion>
     <NeutralLanguage>en</NeutralLanguage>
diff --git a/src/A2A.Client.Transports.JsonRpc/A2A.Client.Transports.JsonRpc.csproj b/src/A2A.Client.Transports.JsonRpc/A2A.Client.Transports.JsonRpc.csproj
index 42814b3..31acc63 100644
--- a/src/A2A.Client.Transports.JsonRpc/A2A.Client.Transports.JsonRpc.csproj
+++ b/src/A2A.Client.Transports.JsonRpc/A2A.Client.Transports.JsonRpc.csproj
@@ -5,7 +5,7 @@
     <ImplicitUsings>enable</ImplicitUsings>
     <Nullable>enable</Nullable>
 	<RootNamespace>A2A.Client.Transports</RootNamespace>
-    <VersionPrefix>0.14.0</VersionPrefix>
+    <VersionPrefix>0.15.0</VersionPrefix>
     <AssemblyVersion>$(VersionPrefix)</AssemblyVersion>
     <FileVersion>$(VersionPrefix)</FileVersion>
     <NeutralLanguage>en</NeutralLanguage>
diff --git a/src/A2A.Client/A2A.Client.csproj b/src/A2A.Client/A2A.Client.csproj
index ad3d354..30a6176 100644
--- a/src/A2A.Client/A2A.Client.csproj
+++ b/src/A2A.Client/A2A.Client.csproj
@@ -5,7 +5,7 @@
     <ImplicitUsings>enable</ImplicitUsings>
     <Nullable>enable</Nullable>
 	<RootNamespace>A2A.Client</RootNamespace>
-    <VersionPrefix>0.14.0</VersionPrefix>
+    <VersionPrefix>0.15.0</VersionPrefix>
     <AssemblyVersion>$(VersionPrefix)</AssemblyVersion>
     <FileVersion>$(VersionPrefix)</FileVersion>
     <NeutralLanguage>en</NeutralLanguage>
diff --git a/src/A2A.Core.JsonRpc/A2A.Core.JsonRpc.csproj b/src/A2A.Core.JsonRpc/A2A.Core.JsonRpc.csproj
index 7461854..820d9d7 100644
--- a/src/A2A.Core.JsonRpc/A2A.Core.JsonRpc.csproj
+++ b/src/A2A.Core.JsonRpc/A2A.Core.JsonRpc.csproj
@@ -5,7 +5,7 @@
     <ImplicitUsings>enable</ImplicitUsings>
     <Nullable>enable</Nullable>
 	<RootNamespace>A2A</RootNamespace>
-    <VersionPrefix>0.14.0</VersionPrefix>
+    <VersionPrefix>0.15.0</VersionPrefix>
     <AssemblyVersion>$(VersionPrefix)</AssemblyVersion>
     <FileVersion>$(VersionPrefix)</FileVersion>
     <NeutralLanguage>en</NeutralLanguage>
diff --git a/src/A2A.Core/A2A.Core.csproj b/src/A2A.Core/A2A.Core.csproj
index 35089c9..a07e281 100644
--- a/src/A2A.Core/A2A.Core.csproj
+++ b/src/A2A.Core/A2A.Core.csproj
@@ -5,7 +5,7 @@
     <ImplicitUsings>enable</ImplicitUsings>
     <Nullable>enable</Nullable>
 	<RootNamespace>A2A</RootNamespace>
-    <VersionPrefix>0.14.0</VersionPrefix>
+    <VersionPrefix>0.15.0</VersionPrefix>
     <AssemblyVersion>$(VersionPrefix)</AssemblyVersion>
     <FileVersion>$(VersionPrefix)</FileVersion>
     <NeutralLanguage>en</NeutralLanguage>
diff --git a/src/A2A.Core/Models/AgentExtension.cs b/src/A2A.Core/Models/AgentExtension.cs
index a2c5372..976c05c 100644
--- a/src/A2A.Core/Models/AgentExtension.cs
+++ b/src/A2A.Core/Models/AgentExtension.cs
@@ -47,6 +47,6 @@ public sealed record AgentExtension
     /// </summary>
     [Description("Optional, extension-specific configuration parameters.")]
     [DataMember(Order = 4, Name = "params"), JsonPropertyOrder(4), JsonPropertyName("params")]
-    public IDictionary<string, JsonNode>? Params { get; set; }
+    public JsonObject? Params { get; set; }
 
 }
\ No newline at end of file
diff --git a/src/A2A.Core/Services/AgentExtensionBuilder.cs b/src/A2A.Core/Services/AgentExtensionBuilder.cs
index dea8f93..8a459fb 100644
--- a/src/A2A.Core/Services/AgentExtensionBuilder.cs
+++ b/src/A2A.Core/Services/AgentExtensionBuilder.cs
@@ -45,10 +45,10 @@ public IAgentExtensionBuilder WithDescription(string description)
     }
 
     /// <inheritdoc/>
-    public IAgentExtensionBuilder WithParameters(IDictionary<string, JsonNode> parameters)
+    public IAgentExtensionBuilder WithParameters(IDictionary<string, JsonNode?> parameters)
     {
         ArgumentNullException.ThrowIfNull(parameters);
-        extension.Params = parameters;
+        extension.Params = new(parameters);
         return this;
     }
 
diff --git a/src/A2A.Core/Services/IAgentExtensionBuilder.cs b/src/A2A.Core/Services/IAgentExtensionBuilder.cs
index d59e127..e836f32 100644
--- a/src/A2A.Core/Services/IAgentExtensionBuilder.cs
+++ b/src/A2A.Core/Services/IAgentExtensionBuilder.cs
@@ -45,7 +45,7 @@ public interface IAgentExtensionBuilder
     /// </summary>
     /// <param name="parameters">An object representing the extension's configuration parameters.</param>
     /// <returns>The builder instance.</returns>
-    IAgentExtensionBuilder WithParameters(IDictionary<string, JsonNode> parameters);
+    IAgentExtensionBuilder WithParameters(IDictionary<string, JsonNode?> parameters);
 
     /// <summary>
     /// Builds and returns the configured <see cref="AgentExtension"/>.
diff --git a/src/A2A.Server.Abstractions/A2A.Server.Abstractions.csproj b/src/A2A.Server.Abstractions/A2A.Server.Abstractions.csproj
index dbf6430..5b07a3c 100644
--- a/src/A2A.Server.Abstractions/A2A.Server.Abstractions.csproj
+++ b/src/A2A.Server.Abstractions/A2A.Server.Abstractions.csproj
@@ -6,7 +6,7 @@
     <ImplicitUsings>enable</ImplicitUsings>
     <Nullable>enable</Nullable>
 	<RootNamespace>A2A.Server</RootNamespace>
-    <VersionPrefix>0.14.0</VersionPrefix>
+    <VersionPrefix>0.15.0</VersionPrefix>
     <AssemblyVersion>$(VersionPrefix)</AssemblyVersion>
     <FileVersion>$(VersionPrefix)</FileVersion>
     <NeutralLanguage>en</NeutralLanguage>
diff --git a/src/A2A.Server.AspNetCore/A2A.Server.csproj b/src/A2A.Server.AspNetCore/A2A.Server.csproj
index 2cbe913..aed90ec 100644
--- a/src/A2A.Server.AspNetCore/A2A.Server.csproj
+++ b/src/A2A.Server.AspNetCore/A2A.Server.csproj
@@ -6,7 +6,7 @@
     <ImplicitUsings>enable</ImplicitUsings>
     <Nullable>enable</Nullable>
 	<RootNamespace>A2A.Server</RootNamespace>
-    <VersionPrefix>0.14.0</VersionPrefix>
+    <VersionPrefix>0.15.0</VersionPrefix>
     <AssemblyVersion>$(VersionPrefix)</AssemblyVersion>
     <FileVersion>$(VersionPrefix)</FileVersion>
     <NeutralLanguage>en</NeutralLanguage>
diff --git a/src/A2A.Server.Persistence.Memory/A2A.Server.Persistence.Memory.csproj b/src/A2A.Server.Persistence.Memory/A2A.Server.Persistence.Memory.csproj
index 6267b3e..dfa34ad 100644
--- a/src/A2A.Server.Persistence.Memory/A2A.Server.Persistence.Memory.csproj
+++ b/src/A2A.Server.Persistence.Memory/A2A.Server.Persistence.Memory.csproj
@@ -6,7 +6,7 @@
     <ImplicitUsings>enable</ImplicitUsings>
     <Nullable>enable</Nullable>
 	<RootNamespace>A2A.Server</RootNamespace>
-    <VersionPrefix>0.14.0</VersionPrefix>
+    <VersionPrefix>0.15.0</VersionPrefix>
     <AssemblyVersion>$(VersionPrefix)</AssemblyVersion>
     <FileVersion>$(VersionPrefix)</FileVersion>
     <NeutralLanguage>en</NeutralLanguage>
diff --git a/src/A2A.Server.Persistence.Redis/A2A.Server.Persistence.Redis.csproj b/src/A2A.Server.Persistence.Redis/A2A.Server.Persistence.Redis.csproj
index e2b0150..f34ef8e 100644
--- a/src/A2A.Server.Persistence.Redis/A2A.Server.Persistence.Redis.csproj
+++ b/src/A2A.Server.Persistence.Redis/A2A.Server.Persistence.Redis.csproj
@@ -6,7 +6,7 @@
     <ImplicitUsings>enable</ImplicitUsings>
     <Nullable>enable</Nullable>
 	<RootNamespace>A2A.Server</RootNamespace>
-    <VersionPrefix>0.14.0</VersionPrefix>
+    <VersionPrefix>0.15.0</VersionPrefix>
     <AssemblyVersion>$(VersionPrefix)</AssemblyVersion>
     <FileVersion>$(VersionPrefix)</FileVersion>
     <NeutralLanguage>en</NeutralLanguage>
diff --git a/src/A2A.Server.Scheduling.Memory/A2A.Server.Scheduling.Memory.csproj b/src/A2A.Server.Scheduling.Memory/A2A.Server.Scheduling.Memory.csproj
index f81ba00..8fd5d23 100644
--- a/src/A2A.Server.Scheduling.Memory/A2A.Server.Scheduling.Memory.csproj
+++ b/src/A2A.Server.Scheduling.Memory/A2A.Server.Scheduling.Memory.csproj
@@ -6,7 +6,7 @@
     <ImplicitUsings>enable</ImplicitUsings>
     <Nullable>enable</Nullable>
 	<RootNamespace>A2A.Server</RootNamespace>
-    <VersionPrefix>0.14.0</VersionPrefix>
+    <VersionPrefix>0.15.0</VersionPrefix>
     <AssemblyVersion>$(VersionPrefix)</AssemblyVersion>
     <FileVersion>$(VersionPrefix)</FileVersion>
     <NeutralLanguage>en</NeutralLanguage>
diff --git a/src/A2A.Server.Scheduling.Quartz/A2A.Server.Scheduling.Quartz.csproj b/src/A2A.Server.Scheduling.Quartz/A2A.Server.Scheduling.Quartz.csproj
index d7d9f21..f5fa208 100644
--- a/src/A2A.Server.Scheduling.Quartz/A2A.Server.Scheduling.Quartz.csproj
+++ b/src/A2A.Server.Scheduling.Quartz/A2A.Server.Scheduling.Quartz.csproj
@@ -6,7 +6,7 @@
     <ImplicitUsings>enable</ImplicitUsings>
     <Nullable>enable</Nullable>
 	<RootNamespace>A2A.Server</RootNamespace>
-    <VersionPrefix>0.14.0</VersionPrefix>
+    <VersionPrefix>0.15.0</VersionPrefix>
     <AssemblyVersion>$(VersionPrefix)</AssemblyVersion>
     <FileVersion>$(VersionPrefix)</FileVersion>
     <NeutralLanguage>en</NeutralLanguage>
diff --git a/src/A2A.Server.Transports.Grpc/A2A.Server.Transports.Grpc.csproj b/src/A2A.Server.Transports.Grpc/A2A.Server.Transports.Grpc.csproj
index f2123b6..df9b18d 100644
--- a/src/A2A.Server.Transports.Grpc/A2A.Server.Transports.Grpc.csproj
+++ b/src/A2A.Server.Transports.Grpc/A2A.Server.Transports.Grpc.csproj
@@ -6,7 +6,7 @@
     <ImplicitUsings>enable</ImplicitUsings>
     <Nullable>enable</Nullable>
 	<RootNamespace>A2A.Server.Transports</RootNamespace>
-    <VersionPrefix>0.14.0</VersionPrefix>
+    <VersionPrefix>0.15.0</VersionPrefix>
     <AssemblyVersion>$(VersionPrefix)</AssemblyVersion>
     <FileVersion>$(VersionPrefix)</FileVersion>
     <NeutralLanguage>en</NeutralLanguage>
diff --git a/src/A2A.Server.Transports.Http/A2A.Server.Transports.Http.csproj b/src/A2A.Server.Transports.Http/A2A.Server.Transports.Http.csproj
index 1576523..268e81e 100644
--- a/src/A2A.Server.Transports.Http/A2A.Server.Transports.Http.csproj
+++ b/src/A2A.Server.Transports.Http/A2A.Server.Transports.Http.csproj
@@ -6,7 +6,7 @@
     <ImplicitUsings>enable</ImplicitUsings>
     <Nullable>enable</Nullable>
 	<RootNamespace>A2A.Server.Transports</RootNamespace>
-    <VersionPrefix>0.14.0</VersionPrefix>
+    <VersionPrefix>0.15.0</VersionPrefix>
     <AssemblyVersion>$(VersionPrefix)</AssemblyVersion>
     <FileVersion>$(VersionPrefix)</FileVersion>
     <NeutralLanguage>en</NeutralLanguage>
diff --git a/src/A2A.Server.Transports.JsonRpc/A2A.Server.Transports.JsonRpc.csproj b/src/A2A.Server.Transports.JsonRpc/A2A.Server.Transports.JsonRpc.csproj
index 72c3549..911c32a 100644
--- a/src/A2A.Server.Transports.JsonRpc/A2A.Server.Transports.JsonRpc.csproj
+++ b/src/A2A.Server.Transports.JsonRpc/A2A.Server.Transports.JsonRpc.csproj
@@ -6,7 +6,7 @@
     <ImplicitUsings>enable</ImplicitUsings>
     <Nullable>enable</Nullable>
 	<RootNamespace>A2A.Server.Transports</RootNamespace>
-    <VersionPrefix>0.14.0</VersionPrefix>
+    <VersionPrefix>0.15.0</VersionPrefix>
     <AssemblyVersion>$(VersionPrefix)</AssemblyVersion>
     <FileVersion>$(VersionPrefix)</FileVersion>
     <NeutralLanguage>en</NeutralLanguage>
diff --git a/tests/A2A.UnitTests/Services/AgentExtensionFactory.cs b/tests/A2A.UnitTests/Services/AgentExtensionFactory.cs
index 5d28ee7..7485504 100644
--- a/tests/A2A.UnitTests/Services/AgentExtensionFactory.cs
+++ b/tests/A2A.UnitTests/Services/AgentExtensionFactory.cs
@@ -21,7 +21,7 @@ internal static class AgentExtensionFactory
         Uri = new Uri("https://example.com/agent-extension"),
         Description = "Sample Agent Extension",
         Required = true,
-        Params = new Dictionary<string, JsonNode>
+        Params = new()
         {
             ["param1"] = "value1",
             ["param2"] = 42