diff --git a/README.md b/README.md
index 3d04470..e70c248 100644
--- a/README.md
+++ b/README.md
@@ -87,8 +87,8 @@ released (Unity: ReflectorNet JSON).
 ### C# (NuGet)
 
 ```xml
-<PackageReference Include="com.IvanMurzak.CodeExec" Version="0.4.0" />
-<PackageReference Include="com.IvanMurzak.CodeExec.Roslyn" Version="0.4.0" />
+<PackageReference Include="com.IvanMurzak.CodeExec" Version="0.4.1" />
+<PackageReference Include="com.IvanMurzak.CodeExec.Roslyn" Version="0.4.1" />
 <PackageReference Include="Microsoft.CodeAnalysis.CSharp" Version="4.8.0" />  <!-- your choice, 3.8+ -->
 ```
 
diff --git a/dotnet/Directory.Build.props b/dotnet/Directory.Build.props
index f6154bc..08ad893 100644
--- a/dotnet/Directory.Build.props
+++ b/dotnet/Directory.Build.props
@@ -6,7 +6,7 @@
     <TreatWarningsAsErrors>true</TreatWarningsAsErrors>
     <NoWarn>$(NoWarn);CS1591</NoWarn>
     <Deterministic>true</Deterministic>
-    <Version>0.4.0</Version>
+    <Version>0.4.1</Version>
     <Authors>Ivan Murzak</Authors>
     <Copyright>Copyright (c) 2026 Ivan Murzak</Copyright>
     <RepositoryUrl>https://github.com/IvanMurzak/Code-Exec</RepositoryUrl>
diff --git a/spec/contract.md b/spec/contract.md
index 8ce15d9..b2ea83b 100644
--- a/spec/contract.md
+++ b/spec/contract.md
@@ -304,8 +304,10 @@ Lengths are in characters: UTF-16 code units in C#, code points in Python. A lim
 
 ## Changelog
 
-- **Unreleased** — C#: a `Monitor.Pulse` sent while a sliced `Monitor.Wait` is between two slices wakes it (it was
-  lost, and the waiter slept until the budget); the agent's `Monitor.Pulse` / `PulseAll` become guard stand-ins (§3.6).
+- **v0.4.1** — C#: the guard keeps its per-thread state in a `ThreadLocal` instead of a `[ThreadStatic]` field of
+  the collectible snippet assembly (a rare process crash in the .NET 10 GC went away with it); a `Monitor.Pulse` sent
+  while a sliced `Monitor.Wait` is between two slices wakes it (it was lost, and the waiter slept until the budget);
+  the agent's `Monitor.Pulse` / `PulseAll` become guard stand-ins (§3.6).
 - **v0.4.0** — execution guards (§3.6): C# snippets, full source and includes stop with `Runtime`
   (`Recursion too deep`) before a stack overflow and with `Timeout` once `timeoutMs` is spent, also in synchronous code
   on the main thread; Python stops with `Timeout` through a watchdog (§4). `timeoutMs` applies to both runtimes; `0`