diff --git a/backend/deploy/e2e/docker-compose.e2e.yml b/backend/deploy/e2e/docker-compose.e2e.yml
index cedfa2af7..f5fcef319 100644
--- a/backend/deploy/e2e/docker-compose.e2e.yml
+++ b/backend/deploy/e2e/docker-compose.e2e.yml
@@ -65,8 +65,10 @@ services:
     volumes:
       - ./fake-codex:/opt/fake-codex:ro
       - artifacts:/var/lib/codespace/artifacts
+      - spool:/var/lib/codespace/spool
     ports:
       - "18081:8080"
 
 volumes:
   artifacts:
+  spool:
diff --git a/backend/tests/CodeSpace.UnitTests/Settings/DurableStorageTopologyTests.cs b/backend/tests/CodeSpace.UnitTests/Settings/DurableStorageTopologyTests.cs
new file mode 100644
index 000000000..a18737531
--- /dev/null
+++ b/backend/tests/CodeSpace.UnitTests/Settings/DurableStorageTopologyTests.cs
@@ -0,0 +1,47 @@
+using YamlDotNet.RepresentationModel;
+using Shouldly;
+
+namespace CodeSpace.UnitTests.Settings;
+
+/// <summary>
+/// The process spool is the recoverable source of truth until its redacted streams reach durable artifact CAS.
+/// Preparing the directory in an image is not persistence: a worker replacement must see the same bytes.
+/// </summary>
+[Trait("Category", "Unit")]
+public class DurableStorageTopologyTests
+{
+    [Theory]
+    [InlineData("docker-compose.yml", "codespace-spool")]
+    [InlineData("backend/deploy/e2e/docker-compose.e2e.yml", "spool")]
+    public void Worker_spool_is_a_declared_named_volume(string relativePath, string volumeName)
+    {
+        var root = Mapping(Load(relativePath));
+        var services = Mapping(root.Children[Scalar("services")]);
+        var worker = Mapping(services.Children[Scalar("worker")]);
+        var mounts = Sequence(worker.Children[Scalar("volumes")]).Children.Select(value => ScalarValue(value)).ToArray();
+        var volumes = Mapping(root.Children[Scalar("volumes")]);
+
+        mounts.ShouldContain($"{volumeName}:{CodeSpace.Core.Settings.DurableRoots.ContainerAgentRunSpool}");
+        volumes.Children.Keys.Select(ScalarValue).ShouldContain(volumeName);
+    }
+
+    private static YamlNode Load(string relativePath)
+    {
+        using var reader = File.OpenText(Path.Combine(FindRepoRoot(), relativePath));
+        var yaml = new YamlStream();
+        yaml.Load(reader);
+        return yaml.Documents.Single().RootNode;
+    }
+
+    private static YamlMappingNode Mapping(YamlNode node) => node.ShouldBeOfType<YamlMappingNode>();
+    private static YamlSequenceNode Sequence(YamlNode node) => node.ShouldBeOfType<YamlSequenceNode>();
+    private static YamlScalarNode Scalar(string value) => new(value);
+    private static string ScalarValue(YamlNode node) => node.ShouldBeOfType<YamlScalarNode>().Value!;
+
+    private static string FindRepoRoot()
+    {
+        for (var dir = new DirectoryInfo(AppContext.BaseDirectory); dir is not null; dir = dir.Parent)
+            if (Directory.Exists(Path.Combine(dir.FullName, "backend"))) return dir.FullName;
+        throw new InvalidOperationException("repo root not found");
+    }
+}
diff --git a/docker-compose.yml b/docker-compose.yml
index 7c567f908..dc4dcb4ea 100644
--- a/docker-compose.yml
+++ b/docker-compose.yml
@@ -126,7 +126,11 @@ services:
       # Sandbox__RequireConfinement: "true"
     volumes:
       - codespace-artifacts:/var/lib/codespace/artifacts
+      # The spool is the recoverable source until stdout/stderr segments reach artifact CAS. Keep it across worker
+      # replacement and share it between same-host worker replicas; production multi-host deployments require RWX.
+      - codespace-spool:/var/lib/codespace/spool
 
 volumes:
   codespace-pgdata:
   codespace-artifacts:
+  codespace-spool: