diff --git a/Directory.Packages.props b/Directory.Packages.props
index e66ab2b..b069213 100644
--- a/Directory.Packages.props
+++ b/Directory.Packages.props
@@ -8,8 +8,6 @@
     <PackageVersion Include="Cratis.Arc.OpenApi" Version="20.48.0" />
     <PackageVersion Include="Microsoft.AspNetCore.OpenApi" Version="10.0.9" />
     <PackageVersion Include="Scalar.AspNetCore" Version="1.2.46" />
-    <PackageVersion Include="Cratis.Chronicle.Testing" Version="15.35.7" />
-    <PackageVersion Include="Cratis.Chronicle.XUnit.Integration" Version="15.35.7" />
     <!-- Aspire Composition (AppHost) -->
     <PackageVersion Include="Aspire.Hosting.AppHost" Version="13.4.2" />
     <PackageVersion Include="Aspire.Hosting.JavaScript" Version="13.4.2" />
@@ -19,19 +17,12 @@
     <PackageVersion Include="Cratis.Chronicle.Aspire" Version="15.35.7" />
     <PackageVersion Include="SharpCompress" Version="1.0.0" />
     <PackageVersion Include="Snappier" Version="1.3.1" />
+    <PackageVersion Include="MessagePack" Version="2.5.303" />
+    <PackageVersion Include="System.Security.Cryptography.Pkcs" Version="10.0.13" />
     <!-- Analysis -->
-    <PackageVersion Include="Microsoft.NET.Test.Sdk" Version="18.7.0" />
     <PackageVersion Include="StyleCop.Analyzers" Version="1.2.0-beta.556" NoWarn="NU5104" />
     <PackageVersion Include="Roslynator.Analyzers" Version="4.15.0" />
     <PackageVersion Include="Meziantou.Analyzer" Version="3.0.114" />
     <PackageVersion Include="Swashbuckle.AspNetCore.SwaggerUI" Version="10.2.1" />
-    <!-- Testing & Specifications -->
-    <PackageVersion Include="Cratis.Specifications" Version="3.0.5" />
-    <PackageVersion Include="Cratis.Specifications.XUnit" Version="3.0.5" />
-    <PackageVersion Include="Testcontainers" Version="4.12.0" />
-    <PackageVersion Include="xunit" Version="2.9.3" />
-    <PackageVersion Include="xunit.runner.visualstudio" Version="3.1.5" />
-    <PackageVersion Include="NSubstitute" Version="5.3.0" />
-    <PackageVersion Include="Microsoft.AspNetCore.Mvc.Testing" Version="10.0.9" />
   </ItemGroup>
 </Project>
diff --git a/EventModelingConference2026/Composition/Composition.csproj b/EventModelingConference2026/Composition/Composition.csproj
index 559c842..83e7c79 100644
--- a/EventModelingConference2026/Composition/Composition.csproj
+++ b/EventModelingConference2026/Composition/Composition.csproj
@@ -15,6 +15,9 @@
         <PackageReference Include="Cratis.Chronicle.Aspire" />
         <PackageReference Include="SharpCompress" />
         <PackageReference Include="Snappier" />
+        <!-- Patch vulnerable transitive dependencies until Aspire updates them. -->
+        <PackageReference Include="MessagePack" />
+        <PackageReference Include="System.Security.Cryptography.Pkcs" />
     </ItemGroup>
 
     <ItemGroup>
diff --git a/EventModelingConference2026/Core/Core.csproj b/EventModelingConference2026/Core/Core.csproj
index eb001d1..0b3b1e6 100644
--- a/EventModelingConference2026/Core/Core.csproj
+++ b/EventModelingConference2026/Core/Core.csproj
@@ -14,37 +14,16 @@
 
     <ItemGroup>
         <PackageReference Include="Cratis" />
+        <PackageReference Include="Cratis.Arc.MongoDB" />
         <PackageReference Include="Cratis.Arc.OpenApi" />
         <PackageReference Include="Microsoft.AspNetCore.OpenApi" />
         <PackageReference Include="Scalar.AspNetCore" />
     </ItemGroup>
 
-    <ItemGroup Condition="'$(Configuration)' == 'Release'">
-        <Compile Remove="**/when_*/*.cs" />
-        <Compile Remove="**/for_*/*.cs" />
-        <Compile Remove="**/given/*.cs" />
-        <Compile Remove="./Specs/*.cs" />
-    </ItemGroup>
-
     <PropertyGroup Condition="'$(Configuration)'=='Debug'">
-        <IsTestProject>true</IsTestProject>
         <IsPackable>false</IsPackable>
     </PropertyGroup>
 
-    <ItemGroup Condition="'$(Configuration)'=='Debug'">
-        <PackageReference Include="xunit" />
-        <PackageReference Include="xunit.runner.visualstudio">
-            <PrivateAssets>all</PrivateAssets>
-            <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
-        </PackageReference>
-        <PackageReference Include="NSubstitute" />
-        <PackageReference Include="Microsoft.NET.Test.Sdk" />
-        <PackageReference Include="Cratis.Specifications.XUnit" />
-        <PackageReference Include="Cratis.Chronicle.Testing" />
-        <PackageReference Include="Cratis.Chronicle.XUnit.Integration" />
-        <PackageReference Include="Testcontainers" />
-    </ItemGroup>
-
     <ItemGroup>
         <Content Remove="package.json" />
         <None Remove="package.json" />
diff --git a/EventModelingConference2026/Core/GlobalUsings.cs b/EventModelingConference2026/Core/GlobalUsings.cs
index c764612..85e0872 100644
--- a/EventModelingConference2026/Core/GlobalUsings.cs
+++ b/EventModelingConference2026/Core/GlobalUsings.cs
@@ -18,11 +18,3 @@
 global using Cratis.Chronicle.Transactions;
 global using Cratis.Concepts;
 global using Microsoft.AspNetCore.Mvc;
-#if DEBUG
-global using Cratis.Chronicle.XUnit;
-global using Cratis.Chronicle.XUnit.Integration;
-global using Cratis.Specifications;
-global using NSubstitute;
-global using NSubstitute.Core;
-global using Xunit;
-#endif