diff --git a/.editorconfig b/.editorconfig
index ecb98adf9..e138b6593 100644
--- a/.editorconfig
+++ b/.editorconfig
@@ -953,7 +953,7 @@ dotnet_diagnostic.VSTHRD003.severity = none
 [tests/OpenCode.Sdk.Tests/Harness/Ownership/OwnedOperationDeadlineTests.cs]
 dotnet_diagnostic.VSTHRD003.severity = none
 
-[tests/OpenCode.Sdk.Tests/Support/SessionLogTranscriptTests.cs]
+[tests/OpenCode.Sdk.Tests/Sessions/Support/SessionLogTranscriptTests.cs]
 dotnet_diagnostic.VSTHRD003.severity = none
 
 # The session-removal fault proof controls interrupt entry and expiry, then drains cancellation
@@ -970,7 +970,7 @@ dotnet_diagnostic.VSTHRD003.severity = none
 # These diagnostic proofs control their own operation deadlines and retain supplied disposal
 # tasks until finally releases and drains them. Winner: causal fixture/status ownership proofs;
 # the rule remains enabled outside these exact files.
-[tests/OpenCode.Sdk.Tests/Support/PtyFailureDiagnosticsTests.cs]
+[tests/OpenCode.Sdk.Tests/Ptys/Support/PtyFailureDiagnosticsTests.cs]
 dotnet_diagnostic.VSTHRD003.severity = none
 
 [tests/OpenCode.Sdk.Tests/Support/ServerDiagnosticScenario.cs]
@@ -1155,7 +1155,7 @@ dotnet_diagnostic.MA0045.severity = none
 # DriveManifestTests.cs documents above - and an async factory would make the arrangement
 # awaitable without making it asynchronous. Winner: the cross-TFM arrangement shape; MA0045
 # remains enabled for every other file.
-[tests/OpenCode.Sdk.Tests/Support/PathCommandShim.cs]
+[tests/OpenCode.Sdk.Tests/Hosting/Launcher/Support/PathCommandShim.cs]
 dotnet_diagnostic.MA0045.severity = none
 
 # Optional<T> is the tri-state carrier for a request property the document declares both optional
diff --git a/docs/engineering/testing-style.md b/docs/engineering/testing-style.md
index d259ee4c4..ab9588c11 100644
--- a/docs/engineering/testing-style.md
+++ b/docs/engineering/testing-style.md
@@ -1,6 +1,6 @@
 # Testing Style — authoring tests
 
-Date: 2026-10-16
+Date: 2026-10-17
 
 Binding authorship style for every test in this repository. `quality-gates.md` owns the
 current assurance posture and completion gates; operational build-out state belongs in
@@ -64,9 +64,11 @@ sized to need:
   like a BCL type shadows it there: tests under `Debug/` declare `OpenCode.Sdk.Tests.Debug` and
   qualify `System.Diagnostics.Debug`. A guard test refuses two source types that project onto
   one test path.
-- A helper or fixture one slice uses lives in that test slice's `Support/` or `Fixtures/`;
-  helpers several slices share stay in the test project's root `Support/`. Live-server harness
-  code lives in `tests/OpenCode.Sdk.Tests/Harness/`. Files another test project links, and the
+- In SDK.Tests, a helper or fixture used by one slice lives in that slice's `Support/` or
+  `Fixtures/`. Helpers and fixtures used by several slices stay in the test project's root
+  `Support/` and `Fixtures/`. Embedded fixtures retain their `Fixtures.` resource-name prefix
+  through explicit `LogicalName` metadata. Live-server harness code lives in
+  `tests/OpenCode.Sdk.Tests/Harness/`. Files another test project links, and the
   embedded-fixture loader, stay in `tests/Shared/`, compiled through explicit links. There is no
   separate test-support project.
 - The mirror rule also applies to test infrastructure: `Harness/X.cs` is tested in
@@ -99,8 +101,9 @@ analyzer enforces it wherever an abstractions assembly is referenced — even te
 **Raw JSON/XML/string-literal dumps pasted inline in test methods are forbidden.** A
 test body states *intent*; the data it runs on lives in one of three sanctioned homes:
 
-1. **Embedded fixture files** — under the owning test project's `Fixtures/` folder,
-   loaded through a resource-loader helper by name. The default for wire-shaped data:
+1. **Embedded fixture files** — in the `Fixtures/` folder of the slice that uses them, or the test
+   project's root `Fixtures/` when several slices share them, loaded through a resource-loader helper
+   by name. The default for wire-shaped data:
    one small file per quirk, named for the construct it isolates, reviewable on its own.
 2. **Typed builders** — for variation families where files would multiply: red tests
    composing a valid base plus exactly one offending construct through the builder. The
diff --git a/tests/OpenCode.Sdk.Tests/Fixtures/Routes/wildcard-path-corpus.json b/tests/OpenCode.Sdk.Tests/FileSystem/Fixtures/wildcard-path-corpus.json
similarity index 100%
rename from tests/OpenCode.Sdk.Tests/Fixtures/Routes/wildcard-path-corpus.json
rename to tests/OpenCode.Sdk.Tests/FileSystem/Fixtures/wildcard-path-corpus.json
diff --git a/tests/OpenCode.Sdk.Tests/Fixtures/Routes/wildcard-path-expected.json b/tests/OpenCode.Sdk.Tests/FileSystem/Fixtures/wildcard-path-expected.json
similarity index 100%
rename from tests/OpenCode.Sdk.Tests/Fixtures/Routes/wildcard-path-expected.json
rename to tests/OpenCode.Sdk.Tests/FileSystem/Fixtures/wildcard-path-expected.json
diff --git a/tests/OpenCode.Sdk.Tests/Fixtures/Server/diagnostic-peer.js b/tests/OpenCode.Sdk.Tests/Harness/Fixtures/diagnostic-peer.js
similarity index 100%
rename from tests/OpenCode.Sdk.Tests/Fixtures/Server/diagnostic-peer.js
rename to tests/OpenCode.Sdk.Tests/Harness/Fixtures/diagnostic-peer.js
diff --git a/tests/OpenCode.Sdk.Tests/Fixtures/Server/exited-diagnostic-peer.js b/tests/OpenCode.Sdk.Tests/Harness/Fixtures/exited-diagnostic-peer.js
similarity index 100%
rename from tests/OpenCode.Sdk.Tests/Fixtures/Server/exited-diagnostic-peer.js
rename to tests/OpenCode.Sdk.Tests/Harness/Fixtures/exited-diagnostic-peer.js
diff --git a/tests/OpenCode.Sdk.Tests/Fixtures/Server/persistent-simulation-host.js b/tests/OpenCode.Sdk.Tests/Harness/Fixtures/persistent-simulation-host.js
similarity index 100%
rename from tests/OpenCode.Sdk.Tests/Fixtures/Server/persistent-simulation-host.js
rename to tests/OpenCode.Sdk.Tests/Harness/Fixtures/persistent-simulation-host.js
diff --git a/tests/OpenCode.Sdk.Tests/Hosting/BackgroundService/Discovery/LoopbackTransportTests.cs b/tests/OpenCode.Sdk.Tests/Hosting/BackgroundService/Discovery/LoopbackTransportTests.cs
index a3ab4bde0..8156434da 100644
--- a/tests/OpenCode.Sdk.Tests/Hosting/BackgroundService/Discovery/LoopbackTransportTests.cs
+++ b/tests/OpenCode.Sdk.Tests/Hosting/BackgroundService/Discovery/LoopbackTransportTests.cs
@@ -1,6 +1,7 @@
 using System.Net;
 using System.Net.Sockets;
 using OpenCode.Sdk.Internal;
+using OpenCode.Sdk.Tests.Hosting.BackgroundService.Support;
 using OpenCode.Sdk.Tests.Support;
 
 namespace OpenCode.Sdk.Tests.Hosting.BackgroundService.Discovery;
diff --git a/tests/OpenCode.Sdk.Tests/Hosting/BackgroundService/Discovery/OpenCodeServerDiscoveryIsolatedProcessTests.cs b/tests/OpenCode.Sdk.Tests/Hosting/BackgroundService/Discovery/OpenCodeServerDiscoveryIsolatedProcessTests.cs
index 25bc3be87..04388f791 100644
--- a/tests/OpenCode.Sdk.Tests/Hosting/BackgroundService/Discovery/OpenCodeServerDiscoveryIsolatedProcessTests.cs
+++ b/tests/OpenCode.Sdk.Tests/Hosting/BackgroundService/Discovery/OpenCodeServerDiscoveryIsolatedProcessTests.cs
@@ -1,6 +1,7 @@
 using System.Globalization;
 using System.Net;
 using OpenCode.Sdk.Tests.Harness;
+using OpenCode.Sdk.Tests.Hosting.BackgroundService.Support;
 using OpenCode.Sdk.Tests.Support;
 using Testably.Abstractions;
 
diff --git a/tests/OpenCode.Sdk.Tests/Hosting/BackgroundService/Discovery/OpenCodeServerDiscoveryLiveTests.cs b/tests/OpenCode.Sdk.Tests/Hosting/BackgroundService/Discovery/OpenCodeServerDiscoveryLiveTests.cs
index 38ec75b7d..04cd4d53c 100644
--- a/tests/OpenCode.Sdk.Tests/Hosting/BackgroundService/Discovery/OpenCodeServerDiscoveryLiveTests.cs
+++ b/tests/OpenCode.Sdk.Tests/Hosting/BackgroundService/Discovery/OpenCodeServerDiscoveryLiveTests.cs
@@ -1,5 +1,6 @@
 using OpenCode.Sdk.Internal;
 using OpenCode.Sdk.Tests.Harness;
+using OpenCode.Sdk.Tests.Hosting.BackgroundService.Support;
 using OpenCode.Sdk.Tests.Support;
 using Testably.Abstractions;
 
diff --git a/tests/OpenCode.Sdk.Tests/Hosting/BackgroundService/Discovery/ServiceInfoProbeTests.cs b/tests/OpenCode.Sdk.Tests/Hosting/BackgroundService/Discovery/ServiceInfoProbeTests.cs
index 6f8184eac..f873dc858 100644
--- a/tests/OpenCode.Sdk.Tests/Hosting/BackgroundService/Discovery/ServiceInfoProbeTests.cs
+++ b/tests/OpenCode.Sdk.Tests/Hosting/BackgroundService/Discovery/ServiceInfoProbeTests.cs
@@ -4,6 +4,7 @@
 using System.Text;
 using OpenCode.Sdk.Internal;
 using OpenCode.Sdk.Tests.Hosting.BackgroundService.Registration;
+using OpenCode.Sdk.Tests.Hosting.BackgroundService.Support;
 using OpenCode.Sdk.Tests.Support;
 
 namespace OpenCode.Sdk.Tests.Hosting.BackgroundService.Discovery;
diff --git a/tests/OpenCode.Sdk.Tests/Hosting/BackgroundService/Ensure/OpenCodeServerEnsureLiveTests.cs b/tests/OpenCode.Sdk.Tests/Hosting/BackgroundService/Ensure/OpenCodeServerEnsureLiveTests.cs
index 3c2209f60..a308a7575 100644
--- a/tests/OpenCode.Sdk.Tests/Hosting/BackgroundService/Ensure/OpenCodeServerEnsureLiveTests.cs
+++ b/tests/OpenCode.Sdk.Tests/Hosting/BackgroundService/Ensure/OpenCodeServerEnsureLiveTests.cs
@@ -1,6 +1,7 @@
 using System.Text;
 using OpenCode.Sdk.Internal;
 using OpenCode.Sdk.Tests.Harness;
+using OpenCode.Sdk.Tests.Hosting.BackgroundService.Support;
 using OpenCode.Sdk.Tests.Support;
 using Testably.Abstractions;
 
diff --git a/tests/OpenCode.Sdk.Tests/Fixtures/BackgroundService/pty-handoff-array-root.json b/tests/OpenCode.Sdk.Tests/Hosting/BackgroundService/Fixtures/pty-handoff-array-root.json
similarity index 100%
rename from tests/OpenCode.Sdk.Tests/Fixtures/BackgroundService/pty-handoff-array-root.json
rename to tests/OpenCode.Sdk.Tests/Hosting/BackgroundService/Fixtures/pty-handoff-array-root.json
diff --git a/tests/OpenCode.Sdk.Tests/Fixtures/BackgroundService/pty-handoff-fractional-pid.json b/tests/OpenCode.Sdk.Tests/Hosting/BackgroundService/Fixtures/pty-handoff-fractional-pid.json
similarity index 100%
rename from tests/OpenCode.Sdk.Tests/Fixtures/BackgroundService/pty-handoff-fractional-pid.json
rename to tests/OpenCode.Sdk.Tests/Hosting/BackgroundService/Fixtures/pty-handoff-fractional-pid.json
diff --git a/tests/OpenCode.Sdk.Tests/Fixtures/BackgroundService/pty-handoff-invalid-handoff.json b/tests/OpenCode.Sdk.Tests/Hosting/BackgroundService/Fixtures/pty-handoff-invalid-handoff.json
similarity index 100%
rename from tests/OpenCode.Sdk.Tests/Fixtures/BackgroundService/pty-handoff-invalid-handoff.json
rename to tests/OpenCode.Sdk.Tests/Hosting/BackgroundService/Fixtures/pty-handoff-invalid-handoff.json
diff --git a/tests/OpenCode.Sdk.Tests/Fixtures/BackgroundService/pty-handoff-malformed.json b/tests/OpenCode.Sdk.Tests/Hosting/BackgroundService/Fixtures/pty-handoff-malformed.json
similarity index 100%
rename from tests/OpenCode.Sdk.Tests/Fixtures/BackgroundService/pty-handoff-malformed.json
rename to tests/OpenCode.Sdk.Tests/Hosting/BackgroundService/Fixtures/pty-handoff-malformed.json
diff --git a/tests/OpenCode.Sdk.Tests/Fixtures/BackgroundService/pty-handoff-missing-expiry.json b/tests/OpenCode.Sdk.Tests/Hosting/BackgroundService/Fixtures/pty-handoff-missing-expiry.json
similarity index 100%
rename from tests/OpenCode.Sdk.Tests/Fixtures/BackgroundService/pty-handoff-missing-expiry.json
rename to tests/OpenCode.Sdk.Tests/Hosting/BackgroundService/Fixtures/pty-handoff-missing-expiry.json
diff --git a/tests/OpenCode.Sdk.Tests/Fixtures/BackgroundService/pty-handoff-missing-source.json b/tests/OpenCode.Sdk.Tests/Hosting/BackgroundService/Fixtures/pty-handoff-missing-source.json
similarity index 100%
rename from tests/OpenCode.Sdk.Tests/Fixtures/BackgroundService/pty-handoff-missing-source.json
rename to tests/OpenCode.Sdk.Tests/Hosting/BackgroundService/Fixtures/pty-handoff-missing-source.json
diff --git a/tests/OpenCode.Sdk.Tests/Fixtures/BackgroundService/pty-handoff-nonfinite-expiry.json b/tests/OpenCode.Sdk.Tests/Hosting/BackgroundService/Fixtures/pty-handoff-nonfinite-expiry.json
similarity index 100%
rename from tests/OpenCode.Sdk.Tests/Fixtures/BackgroundService/pty-handoff-nonfinite-expiry.json
rename to tests/OpenCode.Sdk.Tests/Hosting/BackgroundService/Fixtures/pty-handoff-nonfinite-expiry.json
diff --git a/tests/OpenCode.Sdk.Tests/Fixtures/BackgroundService/pty-handoff-null-handoff.json b/tests/OpenCode.Sdk.Tests/Hosting/BackgroundService/Fixtures/pty-handoff-null-handoff.json
similarity index 100%
rename from tests/OpenCode.Sdk.Tests/Fixtures/BackgroundService/pty-handoff-null-handoff.json
rename to tests/OpenCode.Sdk.Tests/Hosting/BackgroundService/Fixtures/pty-handoff-null-handoff.json
diff --git a/tests/OpenCode.Sdk.Tests/Fixtures/BackgroundService/pty-handoff-response-expired.json b/tests/OpenCode.Sdk.Tests/Hosting/BackgroundService/Fixtures/pty-handoff-response-expired.json
similarity index 100%
rename from tests/OpenCode.Sdk.Tests/Fixtures/BackgroundService/pty-handoff-response-expired.json
rename to tests/OpenCode.Sdk.Tests/Hosting/BackgroundService/Fixtures/pty-handoff-response-expired.json
diff --git a/tests/OpenCode.Sdk.Tests/Fixtures/BackgroundService/pty-handoff-response-invalid.json b/tests/OpenCode.Sdk.Tests/Hosting/BackgroundService/Fixtures/pty-handoff-response-invalid.json
similarity index 100%
rename from tests/OpenCode.Sdk.Tests/Fixtures/BackgroundService/pty-handoff-response-invalid.json
rename to tests/OpenCode.Sdk.Tests/Hosting/BackgroundService/Fixtures/pty-handoff-response-invalid.json
diff --git a/tests/OpenCode.Sdk.Tests/Fixtures/BackgroundService/pty-handoff-response-missing.json b/tests/OpenCode.Sdk.Tests/Hosting/BackgroundService/Fixtures/pty-handoff-response-missing.json
similarity index 100%
rename from tests/OpenCode.Sdk.Tests/Fixtures/BackgroundService/pty-handoff-response-missing.json
rename to tests/OpenCode.Sdk.Tests/Hosting/BackgroundService/Fixtures/pty-handoff-response-missing.json
diff --git a/tests/OpenCode.Sdk.Tests/Fixtures/BackgroundService/pty-handoff-response-null.json b/tests/OpenCode.Sdk.Tests/Hosting/BackgroundService/Fixtures/pty-handoff-response-null.json
similarity index 100%
rename from tests/OpenCode.Sdk.Tests/Fixtures/BackgroundService/pty-handoff-response-null.json
rename to tests/OpenCode.Sdk.Tests/Hosting/BackgroundService/Fixtures/pty-handoff-response-null.json
diff --git a/tests/OpenCode.Sdk.Tests/Fixtures/BackgroundService/pty-handoff-response-ticket.json b/tests/OpenCode.Sdk.Tests/Hosting/BackgroundService/Fixtures/pty-handoff-response-ticket.json
similarity index 100%
rename from tests/OpenCode.Sdk.Tests/Fixtures/BackgroundService/pty-handoff-response-ticket.json
rename to tests/OpenCode.Sdk.Tests/Hosting/BackgroundService/Fixtures/pty-handoff-response-ticket.json
diff --git a/tests/OpenCode.Sdk.Tests/Fixtures/BackgroundService/pty-handoff-sidecar-second-value.json b/tests/OpenCode.Sdk.Tests/Hosting/BackgroundService/Fixtures/pty-handoff-sidecar-second-value.json
similarity index 100%
rename from tests/OpenCode.Sdk.Tests/Fixtures/BackgroundService/pty-handoff-sidecar-second-value.json
rename to tests/OpenCode.Sdk.Tests/Hosting/BackgroundService/Fixtures/pty-handoff-sidecar-second-value.json
diff --git a/tests/OpenCode.Sdk.Tests/Fixtures/BackgroundService/pty-handoff-sidecar-trailing-garbage.json b/tests/OpenCode.Sdk.Tests/Hosting/BackgroundService/Fixtures/pty-handoff-sidecar-trailing-garbage.json
similarity index 100%
rename from tests/OpenCode.Sdk.Tests/Fixtures/BackgroundService/pty-handoff-sidecar-trailing-garbage.json
rename to tests/OpenCode.Sdk.Tests/Hosting/BackgroundService/Fixtures/pty-handoff-sidecar-trailing-garbage.json
diff --git a/tests/OpenCode.Sdk.Tests/Fixtures/BackgroundService/pty-handoff-source-without-id.json b/tests/OpenCode.Sdk.Tests/Hosting/BackgroundService/Fixtures/pty-handoff-source-without-id.json
similarity index 100%
rename from tests/OpenCode.Sdk.Tests/Fixtures/BackgroundService/pty-handoff-source-without-id.json
rename to tests/OpenCode.Sdk.Tests/Hosting/BackgroundService/Fixtures/pty-handoff-source-without-id.json
diff --git a/tests/OpenCode.Sdk.Tests/Fixtures/BackgroundService/pty-handoff-string-pid.json b/tests/OpenCode.Sdk.Tests/Hosting/BackgroundService/Fixtures/pty-handoff-string-pid.json
similarity index 100%
rename from tests/OpenCode.Sdk.Tests/Fixtures/BackgroundService/pty-handoff-string-pid.json
rename to tests/OpenCode.Sdk.Tests/Hosting/BackgroundService/Fixtures/pty-handoff-string-pid.json
diff --git a/tests/OpenCode.Sdk.Tests/Fixtures/BackgroundService/pty-handoff-ticket-second-value.json b/tests/OpenCode.Sdk.Tests/Hosting/BackgroundService/Fixtures/pty-handoff-ticket-second-value.json
similarity index 100%
rename from tests/OpenCode.Sdk.Tests/Fixtures/BackgroundService/pty-handoff-ticket-second-value.json
rename to tests/OpenCode.Sdk.Tests/Hosting/BackgroundService/Fixtures/pty-handoff-ticket-second-value.json
diff --git a/tests/OpenCode.Sdk.Tests/Fixtures/BackgroundService/pty-handoff-ticket-trailing-garbage.json b/tests/OpenCode.Sdk.Tests/Hosting/BackgroundService/Fixtures/pty-handoff-ticket-trailing-garbage.json
similarity index 100%
rename from tests/OpenCode.Sdk.Tests/Fixtures/BackgroundService/pty-handoff-ticket-trailing-garbage.json
rename to tests/OpenCode.Sdk.Tests/Hosting/BackgroundService/Fixtures/pty-handoff-ticket-trailing-garbage.json
diff --git a/tests/OpenCode.Sdk.Tests/Fixtures/BackgroundService/pty-handoff-unknown-members.json b/tests/OpenCode.Sdk.Tests/Hosting/BackgroundService/Fixtures/pty-handoff-unknown-members.json
similarity index 100%
rename from tests/OpenCode.Sdk.Tests/Fixtures/BackgroundService/pty-handoff-unknown-members.json
rename to tests/OpenCode.Sdk.Tests/Hosting/BackgroundService/Fixtures/pty-handoff-unknown-members.json
diff --git a/tests/OpenCode.Sdk.Tests/Fixtures/BackgroundService/pty-handoff-valid.json b/tests/OpenCode.Sdk.Tests/Hosting/BackgroundService/Fixtures/pty-handoff-valid.json
similarity index 100%
rename from tests/OpenCode.Sdk.Tests/Fixtures/BackgroundService/pty-handoff-valid.json
rename to tests/OpenCode.Sdk.Tests/Hosting/BackgroundService/Fixtures/pty-handoff-valid.json
diff --git a/tests/OpenCode.Sdk.Tests/Fixtures/BackgroundService/registration-modern.json b/tests/OpenCode.Sdk.Tests/Hosting/BackgroundService/Fixtures/registration-modern.json
similarity index 100%
rename from tests/OpenCode.Sdk.Tests/Fixtures/BackgroundService/registration-modern.json
rename to tests/OpenCode.Sdk.Tests/Hosting/BackgroundService/Fixtures/registration-modern.json
diff --git a/tests/OpenCode.Sdk.Tests/Fixtures/BackgroundService/service-config-env.json b/tests/OpenCode.Sdk.Tests/Hosting/BackgroundService/Fixtures/service-config-env.json
similarity index 100%
rename from tests/OpenCode.Sdk.Tests/Fixtures/BackgroundService/service-config-env.json
rename to tests/OpenCode.Sdk.Tests/Hosting/BackgroundService/Fixtures/service-config-env.json
diff --git a/tests/OpenCode.Sdk.Tests/Hosting/BackgroundService/Handoff/ServicePtyHandoffScenario.cs b/tests/OpenCode.Sdk.Tests/Hosting/BackgroundService/Handoff/ServicePtyHandoffScenario.cs
index 96175c0dc..89ed689fe 100644
--- a/tests/OpenCode.Sdk.Tests/Hosting/BackgroundService/Handoff/ServicePtyHandoffScenario.cs
+++ b/tests/OpenCode.Sdk.Tests/Hosting/BackgroundService/Handoff/ServicePtyHandoffScenario.cs
@@ -1,6 +1,7 @@
 using System.Net;
 using NSubstitute;
 using OpenCode.Sdk.Internal;
+using OpenCode.Sdk.Tests.Hosting.BackgroundService.Support;
 using OpenCode.Sdk.Tests.Support;
 using Testably.Abstractions.Testing;
 
diff --git a/tests/OpenCode.Sdk.Tests/Support/LoopbackConnectRecord.cs b/tests/OpenCode.Sdk.Tests/Hosting/BackgroundService/Support/LoopbackConnectRecord.cs
similarity index 90%
rename from tests/OpenCode.Sdk.Tests/Support/LoopbackConnectRecord.cs
rename to tests/OpenCode.Sdk.Tests/Hosting/BackgroundService/Support/LoopbackConnectRecord.cs
index cd478daa3..9c6254a95 100644
--- a/tests/OpenCode.Sdk.Tests/Support/LoopbackConnectRecord.cs
+++ b/tests/OpenCode.Sdk.Tests/Hosting/BackgroundService/Support/LoopbackConnectRecord.cs
@@ -1,6 +1,6 @@
 using System.Net.Sockets;
 
-namespace OpenCode.Sdk.Tests.Support;
+namespace OpenCode.Sdk.Tests.Hosting.BackgroundService.Support;
 
 /// <summary>One connect the probe's loopback transport made itself, as <see cref="RecordingLoopbackConnector"/> saw it.</summary>
 /// <param name="SynRetransmissionDisabled">Whether the loopback option took on the socket it connected.</param>
diff --git a/tests/OpenCode.Sdk.Tests/Support/RecordingLoopbackConnector.cs b/tests/OpenCode.Sdk.Tests/Hosting/BackgroundService/Support/RecordingLoopbackConnector.cs
similarity index 95%
rename from tests/OpenCode.Sdk.Tests/Support/RecordingLoopbackConnector.cs
rename to tests/OpenCode.Sdk.Tests/Hosting/BackgroundService/Support/RecordingLoopbackConnector.cs
index ddcd21f93..65725c6a4 100644
--- a/tests/OpenCode.Sdk.Tests/Support/RecordingLoopbackConnector.cs
+++ b/tests/OpenCode.Sdk.Tests/Hosting/BackgroundService/Support/RecordingLoopbackConnector.cs
@@ -2,7 +2,7 @@
 using System.Net.Sockets;
 using OpenCode.Sdk.Internal;
 
-namespace OpenCode.Sdk.Tests.Support;
+namespace OpenCode.Sdk.Tests.Hosting.BackgroundService.Support;
 
 /// <summary>
 /// The platform connect under the probe's loopback transport, recording each connect the transport
diff --git a/tests/OpenCode.Sdk.Tests/Support/ScriptedLoopbackConnector.cs b/tests/OpenCode.Sdk.Tests/Hosting/BackgroundService/Support/ScriptedLoopbackConnector.cs
similarity index 92%
rename from tests/OpenCode.Sdk.Tests/Support/ScriptedLoopbackConnector.cs
rename to tests/OpenCode.Sdk.Tests/Hosting/BackgroundService/Support/ScriptedLoopbackConnector.cs
index 461a24ec0..b914cecad 100644
--- a/tests/OpenCode.Sdk.Tests/Support/ScriptedLoopbackConnector.cs
+++ b/tests/OpenCode.Sdk.Tests/Hosting/BackgroundService/Support/ScriptedLoopbackConnector.cs
@@ -1,7 +1,7 @@
 #if !NET
 using OpenCode.Sdk.Internal;
 
-namespace OpenCode.Sdk.Tests.Support;
+namespace OpenCode.Sdk.Tests.Hosting.BackgroundService.Support;
 
 /// <summary>
 /// A loopback connect that completes in a chosen order, with no socket traffic: it cancels the
diff --git a/tests/OpenCode.Sdk.Tests/Support/ServiceFixtureOutput.cs b/tests/OpenCode.Sdk.Tests/Hosting/BackgroundService/Support/ServiceFixtureOutput.cs
similarity index 97%
rename from tests/OpenCode.Sdk.Tests/Support/ServiceFixtureOutput.cs
rename to tests/OpenCode.Sdk.Tests/Hosting/BackgroundService/Support/ServiceFixtureOutput.cs
index fdb207177..ef1b67d9d 100644
--- a/tests/OpenCode.Sdk.Tests/Support/ServiceFixtureOutput.cs
+++ b/tests/OpenCode.Sdk.Tests/Hosting/BackgroundService/Support/ServiceFixtureOutput.cs
@@ -1,6 +1,6 @@
 using System.Globalization;
 
-namespace OpenCode.Sdk.Tests.Support;
+namespace OpenCode.Sdk.Tests.Hosting.BackgroundService.Support;
 
 /// <summary>
 /// The isolated discovery executable's output as a test reads it: the one stdout line for a found
diff --git a/tests/OpenCode.Sdk.Tests/Support/ServiceTimingData.cs b/tests/OpenCode.Sdk.Tests/Hosting/BackgroundService/Support/ServiceTimingData.cs
similarity index 95%
rename from tests/OpenCode.Sdk.Tests/Support/ServiceTimingData.cs
rename to tests/OpenCode.Sdk.Tests/Hosting/BackgroundService/Support/ServiceTimingData.cs
index 1bb1a136e..147d5e7c0 100644
--- a/tests/OpenCode.Sdk.Tests/Support/ServiceTimingData.cs
+++ b/tests/OpenCode.Sdk.Tests/Hosting/BackgroundService/Support/ServiceTimingData.cs
@@ -1,7 +1,7 @@
 using System.Globalization;
 using OpenCode.Sdk.Internal;
 
-namespace OpenCode.Sdk.Tests.Support;
+namespace OpenCode.Sdk.Tests.Hosting.BackgroundService.Support;
 
 /// <summary>
 /// The probe bound of every background-service test about the probe's answer rather than its
diff --git a/tests/OpenCode.Sdk.Tests/Support/SocketConnectRecorder.cs b/tests/OpenCode.Sdk.Tests/Hosting/BackgroundService/Support/SocketConnectRecorder.cs
similarity index 97%
rename from tests/OpenCode.Sdk.Tests/Support/SocketConnectRecorder.cs
rename to tests/OpenCode.Sdk.Tests/Hosting/BackgroundService/Support/SocketConnectRecorder.cs
index 6debcbdac..4e9e36eef 100644
--- a/tests/OpenCode.Sdk.Tests/Support/SocketConnectRecorder.cs
+++ b/tests/OpenCode.Sdk.Tests/Hosting/BackgroundService/Support/SocketConnectRecorder.cs
@@ -1,7 +1,7 @@
 #if NET
 using System.Diagnostics.Tracing;
 
-namespace OpenCode.Sdk.Tests.Support;
+namespace OpenCode.Sdk.Tests.Hosting.BackgroundService.Support;
 
 /// <summary>
 /// Records this process's socket connect events while it lives, so a test can read that its own
diff --git a/tests/OpenCode.Sdk.Tests/Fixtures/Server/child-tree.js b/tests/OpenCode.Sdk.Tests/Hosting/Launcher/Fixtures/child-tree.js
similarity index 100%
rename from tests/OpenCode.Sdk.Tests/Fixtures/Server/child-tree.js
rename to tests/OpenCode.Sdk.Tests/Hosting/Launcher/Fixtures/child-tree.js
diff --git a/tests/OpenCode.Sdk.Tests/Fixtures/Server/ladder-tree.js b/tests/OpenCode.Sdk.Tests/Hosting/Launcher/Fixtures/ladder-tree.js
similarity index 100%
rename from tests/OpenCode.Sdk.Tests/Fixtures/Server/ladder-tree.js
rename to tests/OpenCode.Sdk.Tests/Hosting/Launcher/Fixtures/ladder-tree.js
diff --git a/tests/OpenCode.Sdk.Tests/Fixtures/Server/stdout-holder.js b/tests/OpenCode.Sdk.Tests/Hosting/Launcher/Fixtures/stdout-holder.js
similarity index 100%
rename from tests/OpenCode.Sdk.Tests/Fixtures/Server/stdout-holder.js
rename to tests/OpenCode.Sdk.Tests/Hosting/Launcher/Fixtures/stdout-holder.js
diff --git a/tests/OpenCode.Sdk.Tests/Hosting/Launcher/OpenCodeServerCommandResolutionTests.cs b/tests/OpenCode.Sdk.Tests/Hosting/Launcher/OpenCodeServerCommandResolutionTests.cs
index c48719bcc..93ddfc364 100644
--- a/tests/OpenCode.Sdk.Tests/Hosting/Launcher/OpenCodeServerCommandResolutionTests.cs
+++ b/tests/OpenCode.Sdk.Tests/Hosting/Launcher/OpenCodeServerCommandResolutionTests.cs
@@ -1,5 +1,6 @@
 using OpenCode.Sdk.Internal;
 using OpenCode.Sdk.Tests.Harness;
+using OpenCode.Sdk.Tests.Hosting.Launcher.Support;
 using OpenCode.Sdk.Tests.Support;
 using Testably.Abstractions;
 
diff --git a/tests/OpenCode.Sdk.Tests/Hosting/Launcher/OpenCodeServerDescriptorTests.cs b/tests/OpenCode.Sdk.Tests/Hosting/Launcher/OpenCodeServerDescriptorTests.cs
index d6e146d24..282a50920 100644
--- a/tests/OpenCode.Sdk.Tests/Hosting/Launcher/OpenCodeServerDescriptorTests.cs
+++ b/tests/OpenCode.Sdk.Tests/Hosting/Launcher/OpenCodeServerDescriptorTests.cs
@@ -2,6 +2,7 @@
 using System.Globalization;
 using OpenCode.Sdk.Internal;
 using OpenCode.Sdk.Tests.Harness;
+using OpenCode.Sdk.Tests.Hosting.Launcher.Support;
 using OpenCode.Sdk.Tests.Support;
 using Testably.Abstractions;
 using TUnit.Assertions.Enums;
diff --git a/tests/OpenCode.Sdk.Tests/Hosting/Launcher/OpenCodeServerExitedTests.cs b/tests/OpenCode.Sdk.Tests/Hosting/Launcher/OpenCodeServerExitedTests.cs
index 0b44654de..567df3095 100644
--- a/tests/OpenCode.Sdk.Tests/Hosting/Launcher/OpenCodeServerExitedTests.cs
+++ b/tests/OpenCode.Sdk.Tests/Hosting/Launcher/OpenCodeServerExitedTests.cs
@@ -1,5 +1,6 @@
 using OpenCode.Sdk.Internal;
 using OpenCode.Sdk.Tests.Harness;
+using OpenCode.Sdk.Tests.Hosting.Launcher.Support;
 using OpenCode.Sdk.Tests.Support;
 using Testably.Abstractions;
 
diff --git a/tests/OpenCode.Sdk.Tests/Hosting/Launcher/OpenCodeServerJobTests.cs b/tests/OpenCode.Sdk.Tests/Hosting/Launcher/OpenCodeServerJobTests.cs
index 115b167dd..d8acc9d54 100644
--- a/tests/OpenCode.Sdk.Tests/Hosting/Launcher/OpenCodeServerJobTests.cs
+++ b/tests/OpenCode.Sdk.Tests/Hosting/Launcher/OpenCodeServerJobTests.cs
@@ -5,6 +5,7 @@
 using Microsoft.Win32.SafeHandles;
 using OpenCode.Sdk.Internal;
 using OpenCode.Sdk.Tests.Harness;
+using OpenCode.Sdk.Tests.Hosting.Launcher.Support;
 using OpenCode.Sdk.Tests.Support;
 using Testably.Abstractions;
 
diff --git a/tests/OpenCode.Sdk.Tests/Hosting/Launcher/OpenCodeServerLifecycleTests.cs b/tests/OpenCode.Sdk.Tests/Hosting/Launcher/OpenCodeServerLifecycleTests.cs
index 88194d641..87d67c3da 100644
--- a/tests/OpenCode.Sdk.Tests/Hosting/Launcher/OpenCodeServerLifecycleTests.cs
+++ b/tests/OpenCode.Sdk.Tests/Hosting/Launcher/OpenCodeServerLifecycleTests.cs
@@ -3,6 +3,7 @@
 using NSubstitute;
 using OpenCode.Sdk.Internal;
 using OpenCode.Sdk.Tests.Harness;
+using OpenCode.Sdk.Tests.Hosting.Launcher.Support;
 using OpenCode.Sdk.Tests.Support;
 using Testably.Abstractions;
 using TUnit.Assertions.Enums;
diff --git a/tests/OpenCode.Sdk.Tests/Hosting/Launcher/OpenCodeServerOwnerTests.cs b/tests/OpenCode.Sdk.Tests/Hosting/Launcher/OpenCodeServerOwnerTests.cs
index 0d87ab679..6521433d7 100644
--- a/tests/OpenCode.Sdk.Tests/Hosting/Launcher/OpenCodeServerOwnerTests.cs
+++ b/tests/OpenCode.Sdk.Tests/Hosting/Launcher/OpenCodeServerOwnerTests.cs
@@ -1,6 +1,7 @@
 using System.Diagnostics;
 using System.Globalization;
 using OpenCode.Sdk.Tests.Harness;
+using OpenCode.Sdk.Tests.Hosting.Launcher.Support;
 using OpenCode.Sdk.Tests.Support;
 using Testably.Abstractions;
 
diff --git a/tests/OpenCode.Sdk.Tests/Hosting/Launcher/OpenCodeServerProcessGroupTests.cs b/tests/OpenCode.Sdk.Tests/Hosting/Launcher/OpenCodeServerProcessGroupTests.cs
index bbc1f9166..e6407194e 100644
--- a/tests/OpenCode.Sdk.Tests/Hosting/Launcher/OpenCodeServerProcessGroupTests.cs
+++ b/tests/OpenCode.Sdk.Tests/Hosting/Launcher/OpenCodeServerProcessGroupTests.cs
@@ -3,6 +3,7 @@
 using NSubstitute;
 using OpenCode.Sdk.Internal;
 using OpenCode.Sdk.Tests.Harness;
+using OpenCode.Sdk.Tests.Hosting.Launcher.Support;
 using OpenCode.Sdk.Tests.Support;
 using Testably.Abstractions;
 
diff --git a/tests/OpenCode.Sdk.Tests/Hosting/Launcher/OpenCodeServerReadinessTests.cs b/tests/OpenCode.Sdk.Tests/Hosting/Launcher/OpenCodeServerReadinessTests.cs
index 9bb19e04d..0b1e790a4 100644
--- a/tests/OpenCode.Sdk.Tests/Hosting/Launcher/OpenCodeServerReadinessTests.cs
+++ b/tests/OpenCode.Sdk.Tests/Hosting/Launcher/OpenCodeServerReadinessTests.cs
@@ -1,6 +1,8 @@
 using NSubstitute;
 using OpenCode.Sdk.Internal;
+using OpenCode.Sdk.Tests.Hosting.Launcher.Support;
 using OpenCode.Sdk.Tests.Support;
+using SdkTestSupport = OpenCode.Sdk.Tests.Support;
 
 namespace OpenCode.Sdk.Tests.Hosting.Launcher;
 
@@ -149,7 +151,7 @@ public Task StartAsync_Should_Keep_A_Recorded_Exit_When_The_Caller_Cancels_Durin
         AssertRecordedAtTimeoutAsync(ExitCommand, EarlyExitDiagnostic, cancellationToken, static async (time, arbitrate, caller) =>
         {
             _ = arbitrate.TrySetResult();
-            await time.WaitForArmedAsync(OwnedServerChild.EarlyEndBound, Support.HangGuard.Bound, count: 2);
+            await time.WaitForArmedAsync(OwnedServerChild.EarlyEndBound, SdkTestSupport.HangGuard.Bound, count: 2);
             await caller.CancelOnWorkerAsync();
         });
 
@@ -180,10 +182,10 @@ private static async Task AssertRecordedAtTimeoutAsync(
         var starting = OpenCodeServer.StartWithSeamsAsync(RecordedOptions(publish), seams, caller.Token);
         try
         {
-            var recorded = await entered.Task.WaitAsync(Support.HangGuard.Bound, cancellationToken);
-            await time.WaitForArmedAsync(ReadinessBound, Support.HangGuard.Bound);
+            var recorded = await entered.Task.WaitAsync(SdkTestSupport.HangGuard.Bound, cancellationToken);
+            await time.WaitForArmedAsync(ReadinessBound, SdkTestSupport.HangGuard.Bound);
             time.Advance(ReadinessBound);
-            await canceled.Task.WaitAsync(Support.HangGuard.Bound, cancellationToken);
+            await canceled.Task.WaitAsync(SdkTestSupport.HangGuard.Bound, cancellationToken);
             // The spawn supplied stdin before the owner entered its wait.
             await PublishRecordedOutcomeAsync(recorded, input!, closingOutput, cancellationToken);
             if (closingOutput is not null)
@@ -263,11 +265,11 @@ private static async Task AssertRecordedAtTimeoutAsync(
     private static async Task PublishRecordedOutcomeAsync(
         Task recorded, Stream input, GatedStream? closingOutput, CancellationToken cancellationToken)
     {
-        await input.WriteAsync(new byte[] { 1 }, cancellationToken).AsTask().WaitAsync(Support.HangGuard.Bound, cancellationToken);
-        await input.FlushAsync(cancellationToken).WaitAsync(Support.HangGuard.Bound, cancellationToken);
+        await input.WriteAsync(new byte[] { 1 }, cancellationToken).AsTask().WaitAsync(SdkTestSupport.HangGuard.Bound, cancellationToken);
+        await input.FlushAsync(cancellationToken).WaitAsync(SdkTestSupport.HangGuard.Bound, cancellationToken);
         closingOutput?.Release();
         Task[] recordedTasks = [recorded];
-        await Task.WhenAll(recordedTasks).WaitAsync(Support.HangGuard.Bound, cancellationToken);
+        await Task.WhenAll(recordedTasks).WaitAsync(SdkTestSupport.HangGuard.Bound, cancellationToken);
     }
 
     private static async Task AssertCallerCancellationAsync(
@@ -289,11 +291,11 @@ private static async Task AdvanceEarlyEndAsync(
         ManualTimeProvider time, Task starting, int count, CancellationToken cancellationToken)
     {
         // A timeout can finish cleanup without a drain; a recorded early end drains first.
-        var draining = time.WaitForArmedAsync(OwnedServerChild.EarlyEndBound, Support.HangGuard.Bound, count);
+        var draining = time.WaitForArmedAsync(OwnedServerChild.EarlyEndBound, SdkTestSupport.HangGuard.Bound, count);
         Task[] startingTasks = [starting];
-        if (await Task.WhenAny(Task.WhenAll(startingTasks), draining).WaitAsync(Support.HangGuard.Bound, cancellationToken) == draining)
+        if (await Task.WhenAny(Task.WhenAll(startingTasks), draining).WaitAsync(SdkTestSupport.HangGuard.Bound, cancellationToken) == draining)
         {
-            await draining.WaitAsync(Support.HangGuard.Bound, cancellationToken);
+            await draining.WaitAsync(SdkTestSupport.HangGuard.Bound, cancellationToken);
             time.Advance(OwnedServerChild.EarlyEndBound);
         }
     }
@@ -340,13 +342,13 @@ private static Func<Task, CancellationToken, Task> HoldCanceledWait(
         try
         {
             Task[] pendingTasks = [pending];
-            await Task.WhenAll(pendingTasks).WaitAsync(token).WaitAsync(Support.HangGuard.Bound, cancellationToken);
+            await Task.WhenAll(pendingTasks).WaitAsync(token).WaitAsync(SdkTestSupport.HangGuard.Bound, cancellationToken);
         }
         catch (OperationCanceledException) when (token.IsCancellationRequested)
         {
             _ = canceled.TrySetResult();
             Task[] arbitrationTasks = [arbitrate.Task];
-            await Task.WhenAll(arbitrationTasks).WaitAsync(Support.HangGuard.Bound, cancellationToken);
+            await Task.WhenAll(arbitrationTasks).WaitAsync(SdkTestSupport.HangGuard.Bound, cancellationToken);
             throw;
         }
     };
@@ -364,7 +366,7 @@ private static async Task AssertStartOutcomeAsync(
         }
         else
         {
-            await Assert.That(async () => await Task.WhenAll(startingTasks).WaitAsync(Support.HangGuard.Bound, cancellationToken)).ThrowsNothing();
+            await Assert.That(async () => await Task.WhenAll(startingTasks).WaitAsync(SdkTestSupport.HangGuard.Bound, cancellationToken)).ThrowsNothing();
             var server = await startingTasks[0];
             await Assert.That(server.Endpoint).IsEqualTo(new Uri(ReadyEndpoint));
             await Assert.That(server.ChildExited.IsCompleted).IsFalse();
@@ -397,7 +399,7 @@ await starting.ContinueWith(static completed => _ = completed.Exception, Cancell
                 {
                     if (originalOutput is not null)
                     {
-                        await originalOutput.DisposeAsync().AsTask().WaitAsync(Support.HangGuard.Bound);
+                        await originalOutput.DisposeAsync().AsTask().WaitAsync(SdkTestSupport.HangGuard.Bound);
                     }
                 }
                 finally
diff --git a/tests/OpenCode.Sdk.Tests/Hosting/Launcher/OpenCodeServerWindowsTests.cs b/tests/OpenCode.Sdk.Tests/Hosting/Launcher/OpenCodeServerWindowsTests.cs
index b032ee116..6102a5cda 100644
--- a/tests/OpenCode.Sdk.Tests/Hosting/Launcher/OpenCodeServerWindowsTests.cs
+++ b/tests/OpenCode.Sdk.Tests/Hosting/Launcher/OpenCodeServerWindowsTests.cs
@@ -1,6 +1,7 @@
 using System.Globalization;
 using OpenCode.Sdk.Internal;
 using OpenCode.Sdk.Tests.Harness;
+using OpenCode.Sdk.Tests.Hosting.Launcher.Support;
 using OpenCode.Sdk.Tests.Support;
 using Testably.Abstractions;
 
diff --git a/tests/OpenCode.Sdk.Tests/Hosting/Launcher/OpenCodeServerWorkingDirectoryTests.cs b/tests/OpenCode.Sdk.Tests/Hosting/Launcher/OpenCodeServerWorkingDirectoryTests.cs
index e4238ca5a..1a1563d8b 100644
--- a/tests/OpenCode.Sdk.Tests/Hosting/Launcher/OpenCodeServerWorkingDirectoryTests.cs
+++ b/tests/OpenCode.Sdk.Tests/Hosting/Launcher/OpenCodeServerWorkingDirectoryTests.cs
@@ -1,6 +1,7 @@
 using System.Globalization;
 using OpenCode.Sdk.Internal;
 using OpenCode.Sdk.Tests.Harness;
+using OpenCode.Sdk.Tests.Hosting.Launcher.Support;
 using OpenCode.Sdk.Tests.Support;
 using Testably.Abstractions;
 
diff --git a/tests/OpenCode.Sdk.Tests/Hosting/Launcher/OwnedServerChildTests.cs b/tests/OpenCode.Sdk.Tests/Hosting/Launcher/OwnedServerChildTests.cs
index c3c99cb01..181b3ff3b 100644
--- a/tests/OpenCode.Sdk.Tests/Hosting/Launcher/OwnedServerChildTests.cs
+++ b/tests/OpenCode.Sdk.Tests/Hosting/Launcher/OwnedServerChildTests.cs
@@ -2,6 +2,7 @@
 using System.Text;
 using NSubstitute;
 using OpenCode.Sdk.Internal;
+using OpenCode.Sdk.Tests.Hosting.Launcher.Support;
 using OpenCode.Sdk.Tests.Support;
 using TUnit.Assertions.Enums;
 
diff --git a/tests/OpenCode.Sdk.Tests/Support/LadderTree.cs b/tests/OpenCode.Sdk.Tests/Hosting/Launcher/Support/LadderTree.cs
similarity index 98%
rename from tests/OpenCode.Sdk.Tests/Support/LadderTree.cs
rename to tests/OpenCode.Sdk.Tests/Hosting/Launcher/Support/LadderTree.cs
index 17a1c4cdb..0f135849e 100644
--- a/tests/OpenCode.Sdk.Tests/Support/LadderTree.cs
+++ b/tests/OpenCode.Sdk.Tests/Hosting/Launcher/Support/LadderTree.cs
@@ -1,8 +1,9 @@
 using System.Globalization;
 using OpenCode.Sdk.Internal;
 using OpenCode.Sdk.Tests.Harness;
+using OpenCode.Sdk.Tests.Support;
 
-namespace OpenCode.Sdk.Tests.Support;
+namespace OpenCode.Sdk.Tests.Hosting.Launcher.Support;
 
 /// <summary>
 /// The <c>ladder-tree.js</c> server stand-in: a root with the children a flag list asks for, each
diff --git a/tests/OpenCode.Sdk.Tests/Support/LauncherHost.cs b/tests/OpenCode.Sdk.Tests/Hosting/Launcher/Support/LauncherHost.cs
similarity index 99%
rename from tests/OpenCode.Sdk.Tests/Support/LauncherHost.cs
rename to tests/OpenCode.Sdk.Tests/Hosting/Launcher/Support/LauncherHost.cs
index 8f68400ea..adbe394b7 100644
--- a/tests/OpenCode.Sdk.Tests/Support/LauncherHost.cs
+++ b/tests/OpenCode.Sdk.Tests/Hosting/Launcher/Support/LauncherHost.cs
@@ -6,9 +6,10 @@
 using Microsoft.Win32.SafeHandles;
 using OpenCode.Sdk.Internal;
 using OpenCode.Sdk.Tests.Harness;
+using OpenCode.Sdk.Tests.Support;
 using Testably.Abstractions;
 
-namespace OpenCode.Sdk.Tests.Support;
+namespace OpenCode.Sdk.Tests.Hosting.Launcher.Support;
 
 /// <summary>
 /// The service fixture's <c>launcher-host</c> mode: a separate .NET process that owns one
diff --git a/tests/OpenCode.Sdk.Tests/Support/LauncherHostIgnores.cs b/tests/OpenCode.Sdk.Tests/Hosting/Launcher/Support/LauncherHostIgnores.cs
similarity index 90%
rename from tests/OpenCode.Sdk.Tests/Support/LauncherHostIgnores.cs
rename to tests/OpenCode.Sdk.Tests/Hosting/Launcher/Support/LauncherHostIgnores.cs
index 460e49c76..096ae2bf4 100644
--- a/tests/OpenCode.Sdk.Tests/Support/LauncherHostIgnores.cs
+++ b/tests/OpenCode.Sdk.Tests/Hosting/Launcher/Support/LauncherHostIgnores.cs
@@ -1,4 +1,4 @@
-namespace OpenCode.Sdk.Tests.Support;
+namespace OpenCode.Sdk.Tests.Hosting.Launcher.Support;
 
 /// <summary>The signal a <see cref="LauncherHost"/> starts with ignored, inherited the way a real host inherits it.</summary>
 internal enum LauncherHostIgnores
diff --git a/tests/OpenCode.Sdk.Tests/Support/MissingWorkingDirectoryAction.cs b/tests/OpenCode.Sdk.Tests/Hosting/Launcher/Support/MissingWorkingDirectoryAction.cs
similarity index 91%
rename from tests/OpenCode.Sdk.Tests/Support/MissingWorkingDirectoryAction.cs
rename to tests/OpenCode.Sdk.Tests/Hosting/Launcher/Support/MissingWorkingDirectoryAction.cs
index 3546a5904..cfbce3c42 100644
--- a/tests/OpenCode.Sdk.Tests/Support/MissingWorkingDirectoryAction.cs
+++ b/tests/OpenCode.Sdk.Tests/Hosting/Launcher/Support/MissingWorkingDirectoryAction.cs
@@ -1,6 +1,6 @@
 using OpenCode.Sdk.Internal;
 
-namespace OpenCode.Sdk.Tests.Support;
+namespace OpenCode.Sdk.Tests.Hosting.Launcher.Support;
 
 /// <summary>
 /// A C library without <c>posix_spawn_file_actions_addchdir_np</c>, as glibc before 2.29 is: the
diff --git a/tests/OpenCode.Sdk.Tests/Support/PathCommandShim.cs b/tests/OpenCode.Sdk.Tests/Hosting/Launcher/Support/PathCommandShim.cs
similarity index 98%
rename from tests/OpenCode.Sdk.Tests/Support/PathCommandShim.cs
rename to tests/OpenCode.Sdk.Tests/Hosting/Launcher/Support/PathCommandShim.cs
index 2b052bb15..d252e3a89 100644
--- a/tests/OpenCode.Sdk.Tests/Support/PathCommandShim.cs
+++ b/tests/OpenCode.Sdk.Tests/Hosting/Launcher/Support/PathCommandShim.cs
@@ -2,7 +2,7 @@
 using System.Text;
 using OpenCode.Sdk.Tests.Harness;
 
-namespace OpenCode.Sdk.Tests.Support;
+namespace OpenCode.Sdk.Tests.Hosting.Launcher.Support;
 
 /// <summary>
 /// An npm-shaped command shim on the process PATH: a temporary directory holding one Windows
diff --git a/tests/OpenCode.Sdk.Tests/Support/ProbeOnlyChildExit.cs b/tests/OpenCode.Sdk.Tests/Hosting/Launcher/Support/ProbeOnlyChildExit.cs
similarity index 94%
rename from tests/OpenCode.Sdk.Tests/Support/ProbeOnlyChildExit.cs
rename to tests/OpenCode.Sdk.Tests/Hosting/Launcher/Support/ProbeOnlyChildExit.cs
index d633bfca1..86a1d7c9f 100644
--- a/tests/OpenCode.Sdk.Tests/Support/ProbeOnlyChildExit.cs
+++ b/tests/OpenCode.Sdk.Tests/Hosting/Launcher/Support/ProbeOnlyChildExit.cs
@@ -1,6 +1,6 @@
 using OpenCode.Sdk.Internal;
 
-namespace OpenCode.Sdk.Tests.Support;
+namespace OpenCode.Sdk.Tests.Hosting.Launcher.Support;
 
 /// <summary>
 /// The real exit-status seam, reporting that the kernel reaps this process's children itself, as
diff --git a/tests/OpenCode.Sdk.Tests/Support/RecordingTreeKill.cs b/tests/OpenCode.Sdk.Tests/Hosting/Launcher/Support/RecordingTreeKill.cs
similarity index 96%
rename from tests/OpenCode.Sdk.Tests/Support/RecordingTreeKill.cs
rename to tests/OpenCode.Sdk.Tests/Hosting/Launcher/Support/RecordingTreeKill.cs
index 318b3dbac..3c07a97c0 100644
--- a/tests/OpenCode.Sdk.Tests/Support/RecordingTreeKill.cs
+++ b/tests/OpenCode.Sdk.Tests/Hosting/Launcher/Support/RecordingTreeKill.cs
@@ -2,7 +2,7 @@
 using System.Diagnostics;
 using OpenCode.Sdk.Internal;
 
-namespace OpenCode.Sdk.Tests.Support;
+namespace OpenCode.Sdk.Tests.Hosting.Launcher.Support;
 
 /// <summary>
 /// The shipped Windows tree kill behind a recorder: every run is recorded with the time since the
diff --git a/tests/OpenCode.Sdk.Tests/Support/ServerStartupTreeHandshake.cs b/tests/OpenCode.Sdk.Tests/Hosting/Launcher/Support/ServerStartupTreeHandshake.cs
similarity index 98%
rename from tests/OpenCode.Sdk.Tests/Support/ServerStartupTreeHandshake.cs
rename to tests/OpenCode.Sdk.Tests/Hosting/Launcher/Support/ServerStartupTreeHandshake.cs
index a48269223..d0e1b6760 100644
--- a/tests/OpenCode.Sdk.Tests/Support/ServerStartupTreeHandshake.cs
+++ b/tests/OpenCode.Sdk.Tests/Hosting/Launcher/Support/ServerStartupTreeHandshake.cs
@@ -3,7 +3,7 @@
 using System.Net;
 using System.Net.Sockets;
 
-namespace OpenCode.Sdk.Tests.Support;
+namespace OpenCode.Sdk.Tests.Hosting.Launcher.Support;
 
 /// <summary>
 /// Owns independent root and child control leases, authenticated and observed live before ACK.
diff --git a/tests/OpenCode.Sdk.Tests/Support/ServerStartupTreeLease.cs b/tests/OpenCode.Sdk.Tests/Hosting/Launcher/Support/ServerStartupTreeLease.cs
similarity index 98%
rename from tests/OpenCode.Sdk.Tests/Support/ServerStartupTreeLease.cs
rename to tests/OpenCode.Sdk.Tests/Hosting/Launcher/Support/ServerStartupTreeLease.cs
index 6691fe3eb..762d24457 100644
--- a/tests/OpenCode.Sdk.Tests/Support/ServerStartupTreeLease.cs
+++ b/tests/OpenCode.Sdk.Tests/Hosting/Launcher/Support/ServerStartupTreeLease.cs
@@ -5,7 +5,7 @@
 using System.Text;
 using System.Text.Json;
 
-namespace OpenCode.Sdk.Tests.Support;
+namespace OpenCode.Sdk.Tests.Hosting.Launcher.Support;
 
 /// <summary>
 /// Owns one authenticated fixture connection and its process observation. Releasing the connection
diff --git a/tests/OpenCode.Sdk.Tests/Support/ServerStartupTreeScenario.cs b/tests/OpenCode.Sdk.Tests/Hosting/Launcher/Support/ServerStartupTreeScenario.cs
similarity index 99%
rename from tests/OpenCode.Sdk.Tests/Support/ServerStartupTreeScenario.cs
rename to tests/OpenCode.Sdk.Tests/Hosting/Launcher/Support/ServerStartupTreeScenario.cs
index 4e6528fb8..b4431f7ab 100644
--- a/tests/OpenCode.Sdk.Tests/Support/ServerStartupTreeScenario.cs
+++ b/tests/OpenCode.Sdk.Tests/Hosting/Launcher/Support/ServerStartupTreeScenario.cs
@@ -5,7 +5,7 @@
 using OpenCode.Sdk.Tests.Harness;
 using Testably.Abstractions;
 
-namespace OpenCode.Sdk.Tests.Support;
+namespace OpenCode.Sdk.Tests.Hosting.Launcher.Support;
 
 /// <summary>
 /// Starts the launcher against a cooperating Bun process tree and owns the startup and bounded
diff --git a/tests/OpenCode.Sdk.Tests/Support/SignalStateReport.cs b/tests/OpenCode.Sdk.Tests/Hosting/Launcher/Support/SignalStateReport.cs
similarity index 97%
rename from tests/OpenCode.Sdk.Tests/Support/SignalStateReport.cs
rename to tests/OpenCode.Sdk.Tests/Hosting/Launcher/Support/SignalStateReport.cs
index 63d3cd8ba..e4c69c3bc 100644
--- a/tests/OpenCode.Sdk.Tests/Support/SignalStateReport.cs
+++ b/tests/OpenCode.Sdk.Tests/Hosting/Launcher/Support/SignalStateReport.cs
@@ -1,4 +1,4 @@
-namespace OpenCode.Sdk.Tests.Support;
+namespace OpenCode.Sdk.Tests.Hosting.Launcher.Support;
 
 /// <summary>
 /// A server stand-in that reports the signal state it started with: the readiness line first, then
diff --git a/tests/OpenCode.Sdk.Tests/Support/SpawnWithoutStandardOutput.cs b/tests/OpenCode.Sdk.Tests/Hosting/Launcher/Support/SpawnWithoutStandardOutput.cs
similarity index 96%
rename from tests/OpenCode.Sdk.Tests/Support/SpawnWithoutStandardOutput.cs
rename to tests/OpenCode.Sdk.Tests/Hosting/Launcher/Support/SpawnWithoutStandardOutput.cs
index f0cc6d39c..486e1e15a 100644
--- a/tests/OpenCode.Sdk.Tests/Support/SpawnWithoutStandardOutput.cs
+++ b/tests/OpenCode.Sdk.Tests/Hosting/Launcher/Support/SpawnWithoutStandardOutput.cs
@@ -1,6 +1,6 @@
 using OpenCode.Sdk.Internal;
 
-namespace OpenCode.Sdk.Tests.Support;
+namespace OpenCode.Sdk.Tests.Hosting.Launcher.Support;
 
 /// <summary>
 /// The shipped spawn of either platform, with the read end of the child's stdout closed and
diff --git a/tests/OpenCode.Sdk.Tests/Support/TestJob.cs b/tests/OpenCode.Sdk.Tests/Hosting/Launcher/Support/TestJob.cs
similarity index 97%
rename from tests/OpenCode.Sdk.Tests/Support/TestJob.cs
rename to tests/OpenCode.Sdk.Tests/Hosting/Launcher/Support/TestJob.cs
index aa5f02717..68cf399bf 100644
--- a/tests/OpenCode.Sdk.Tests/Support/TestJob.cs
+++ b/tests/OpenCode.Sdk.Tests/Hosting/Launcher/Support/TestJob.cs
@@ -2,7 +2,7 @@
 using System.Runtime.InteropServices;
 using OpenCode.Sdk.Internal;
 
-namespace OpenCode.Sdk.Tests.Support;
+namespace OpenCode.Sdk.Tests.Hosting.Launcher.Support;
 
 /// <summary>
 /// A job of the test's own, for a launcher host that must itself run in a job, as a host started by
diff --git a/tests/OpenCode.Sdk.Tests/Fixtures/Serialization/known-command-attempt-complete.json b/tests/OpenCode.Sdk.Tests/Integrations/Fixtures/known-command-attempt-complete.json
similarity index 100%
rename from tests/OpenCode.Sdk.Tests/Fixtures/Serialization/known-command-attempt-complete.json
rename to tests/OpenCode.Sdk.Tests/Integrations/Fixtures/known-command-attempt-complete.json
diff --git a/tests/OpenCode.Sdk.Tests/Fixtures/Serialization/known-mcp-server.json b/tests/OpenCode.Sdk.Tests/McpServers/Fixtures/known-mcp-server.json
similarity index 100%
rename from tests/OpenCode.Sdk.Tests/Fixtures/Serialization/known-mcp-server.json
rename to tests/OpenCode.Sdk.Tests/McpServers/Fixtures/known-mcp-server.json
diff --git a/tests/OpenCode.Sdk.Tests/OpenCode.Sdk.Tests.csproj b/tests/OpenCode.Sdk.Tests/OpenCode.Sdk.Tests.csproj
index 4f1ad50cb..934d6f9f5 100644
--- a/tests/OpenCode.Sdk.Tests/OpenCode.Sdk.Tests.csproj
+++ b/tests/OpenCode.Sdk.Tests/OpenCode.Sdk.Tests.csproj
@@ -73,4 +73,99 @@
     <EmbeddedResource Include="Fixtures/**/*.md" />
   </ItemGroup>
 
+  <ItemGroup>
+    <EmbeddedResource Include="Hosting/BackgroundService/Fixtures/pty-handoff-array-root.json" LogicalName="OpenCode.Sdk.Tests.Fixtures.BackgroundService.pty-handoff-array-root.json" />
+    <EmbeddedResource Include="Hosting/BackgroundService/Fixtures/pty-handoff-fractional-pid.json" LogicalName="OpenCode.Sdk.Tests.Fixtures.BackgroundService.pty-handoff-fractional-pid.json" />
+    <EmbeddedResource Include="Hosting/BackgroundService/Fixtures/pty-handoff-invalid-handoff.json" LogicalName="OpenCode.Sdk.Tests.Fixtures.BackgroundService.pty-handoff-invalid-handoff.json" />
+    <EmbeddedResource Include="Hosting/BackgroundService/Fixtures/pty-handoff-malformed.json" LogicalName="OpenCode.Sdk.Tests.Fixtures.BackgroundService.pty-handoff-malformed.json" />
+    <EmbeddedResource Include="Hosting/BackgroundService/Fixtures/pty-handoff-missing-expiry.json" LogicalName="OpenCode.Sdk.Tests.Fixtures.BackgroundService.pty-handoff-missing-expiry.json" />
+    <EmbeddedResource Include="Hosting/BackgroundService/Fixtures/pty-handoff-missing-source.json" LogicalName="OpenCode.Sdk.Tests.Fixtures.BackgroundService.pty-handoff-missing-source.json" />
+    <EmbeddedResource Include="Hosting/BackgroundService/Fixtures/pty-handoff-nonfinite-expiry.json" LogicalName="OpenCode.Sdk.Tests.Fixtures.BackgroundService.pty-handoff-nonfinite-expiry.json" />
+    <EmbeddedResource Include="Hosting/BackgroundService/Fixtures/pty-handoff-null-handoff.json" LogicalName="OpenCode.Sdk.Tests.Fixtures.BackgroundService.pty-handoff-null-handoff.json" />
+    <EmbeddedResource Include="Hosting/BackgroundService/Fixtures/pty-handoff-response-expired.json" LogicalName="OpenCode.Sdk.Tests.Fixtures.BackgroundService.pty-handoff-response-expired.json" />
+    <EmbeddedResource Include="Hosting/BackgroundService/Fixtures/pty-handoff-response-invalid.json" LogicalName="OpenCode.Sdk.Tests.Fixtures.BackgroundService.pty-handoff-response-invalid.json" />
+    <EmbeddedResource Include="Hosting/BackgroundService/Fixtures/pty-handoff-response-missing.json" LogicalName="OpenCode.Sdk.Tests.Fixtures.BackgroundService.pty-handoff-response-missing.json" />
+    <EmbeddedResource Include="Hosting/BackgroundService/Fixtures/pty-handoff-response-null.json" LogicalName="OpenCode.Sdk.Tests.Fixtures.BackgroundService.pty-handoff-response-null.json" />
+    <EmbeddedResource Include="Hosting/BackgroundService/Fixtures/pty-handoff-response-ticket.json" LogicalName="OpenCode.Sdk.Tests.Fixtures.BackgroundService.pty-handoff-response-ticket.json" />
+    <EmbeddedResource Include="Hosting/BackgroundService/Fixtures/pty-handoff-sidecar-second-value.json" LogicalName="OpenCode.Sdk.Tests.Fixtures.BackgroundService.pty-handoff-sidecar-second-value.json" />
+    <EmbeddedResource Include="Hosting/BackgroundService/Fixtures/pty-handoff-sidecar-trailing-garbage.json" LogicalName="OpenCode.Sdk.Tests.Fixtures.BackgroundService.pty-handoff-sidecar-trailing-garbage.json" />
+    <EmbeddedResource Include="Hosting/BackgroundService/Fixtures/pty-handoff-source-without-id.json" LogicalName="OpenCode.Sdk.Tests.Fixtures.BackgroundService.pty-handoff-source-without-id.json" />
+    <EmbeddedResource Include="Hosting/BackgroundService/Fixtures/pty-handoff-string-pid.json" LogicalName="OpenCode.Sdk.Tests.Fixtures.BackgroundService.pty-handoff-string-pid.json" />
+    <EmbeddedResource Include="Hosting/BackgroundService/Fixtures/pty-handoff-ticket-second-value.json" LogicalName="OpenCode.Sdk.Tests.Fixtures.BackgroundService.pty-handoff-ticket-second-value.json" />
+    <EmbeddedResource Include="Hosting/BackgroundService/Fixtures/pty-handoff-ticket-trailing-garbage.json" LogicalName="OpenCode.Sdk.Tests.Fixtures.BackgroundService.pty-handoff-ticket-trailing-garbage.json" />
+    <EmbeddedResource Include="Hosting/BackgroundService/Fixtures/pty-handoff-unknown-members.json" LogicalName="OpenCode.Sdk.Tests.Fixtures.BackgroundService.pty-handoff-unknown-members.json" />
+    <EmbeddedResource Include="Hosting/BackgroundService/Fixtures/pty-handoff-valid.json" LogicalName="OpenCode.Sdk.Tests.Fixtures.BackgroundService.pty-handoff-valid.json" />
+    <EmbeddedResource Include="Hosting/BackgroundService/Fixtures/registration-modern.json" LogicalName="OpenCode.Sdk.Tests.Fixtures.BackgroundService.registration-modern.json" />
+    <EmbeddedResource Include="Hosting/BackgroundService/Fixtures/service-config-env.json" LogicalName="OpenCode.Sdk.Tests.Fixtures.BackgroundService.service-config-env.json" />
+    <EmbeddedResource Include="Ptys/Fixtures/cursor-second-value.json" LogicalName="OpenCode.Sdk.Tests.Fixtures.Ptys.cursor-second-value.json" />
+    <EmbeddedResource Include="Ptys/Fixtures/cursor-trailing-garbage.json" LogicalName="OpenCode.Sdk.Tests.Fixtures.Ptys.cursor-trailing-garbage.json" />
+    <EmbeddedResource Include="Ptys/Fixtures/cursor-truncated-after-value.json" LogicalName="OpenCode.Sdk.Tests.Fixtures.Ptys.cursor-truncated-after-value.json" />
+    <EmbeddedResource Include="Ptys/Fixtures/cursor-valid-whitespace.json" LogicalName="OpenCode.Sdk.Tests.Fixtures.Ptys.cursor-valid-whitespace.json" />
+    <EmbeddedResource Include="Ptys/Fixtures/terminal-peer.js" LogicalName="OpenCode.Sdk.Tests.Fixtures.Ptys.terminal-peer.js" />
+    <EmbeddedResource Include="FileSystem/Fixtures/wildcard-path-corpus.json" LogicalName="OpenCode.Sdk.Tests.Fixtures.Routes.wildcard-path-corpus.json" />
+    <EmbeddedResource Include="FileSystem/Fixtures/wildcard-path-expected.json" LogicalName="OpenCode.Sdk.Tests.Fixtures.Routes.wildcard-path-expected.json" />
+    <EmbeddedResource Include="Rpc/Fixtures/rpc-call-input.json" LogicalName="OpenCode.Sdk.Tests.Fixtures.Rpc.rpc-call-input.json" />
+    <EmbeddedResource Include="Serialization/Fixtures/duplicate-known-session-message-marker.json" LogicalName="OpenCode.Sdk.Tests.Fixtures.Serialization.duplicate-known-session-message-marker.json" />
+    <EmbeddedResource Include="Serialization/Fixtures/duplicate-unknown-session-message-marker.json" LogicalName="OpenCode.Sdk.Tests.Fixtures.Serialization.duplicate-unknown-session-message-marker.json" />
+    <EmbeddedResource Include="Serialization/Fixtures/empty-assistant-marker.json" LogicalName="OpenCode.Sdk.Tests.Fixtures.Serialization.empty-assistant-marker.json" />
+    <EmbeddedResource Include="Serialization/Fixtures/error-carrying-both-markers.json" LogicalName="OpenCode.Sdk.Tests.Fixtures.Serialization.error-carrying-both-markers.json" />
+    <EmbeddedResource Include="Serialization/Fixtures/known-assistant-content.json" LogicalName="OpenCode.Sdk.Tests.Fixtures.Serialization.known-assistant-content.json" />
+    <EmbeddedResource Include="Integrations/Fixtures/known-command-attempt-complete.json" LogicalName="OpenCode.Sdk.Tests.Fixtures.Serialization.known-command-attempt-complete.json" />
+    <EmbeddedResource Include="Serialization/Fixtures/known-compaction-message.json" LogicalName="OpenCode.Sdk.Tests.Fixtures.Serialization.known-compaction-message.json" />
+    <EmbeddedResource Include="Sessions/Fixtures/known-inbox-compaction.json" LogicalName="OpenCode.Sdk.Tests.Fixtures.Serialization.known-inbox-compaction.json" />
+    <EmbeddedResource Include="McpServers/Fixtures/known-mcp-server.json" LogicalName="OpenCode.Sdk.Tests.Fixtures.Serialization.known-mcp-server.json" />
+    <EmbeddedResource Include="Sessions/Fixtures/known-permission.json" LogicalName="OpenCode.Sdk.Tests.Fixtures.Serialization.known-permission.json" />
+    <EmbeddedResource Include="PersistentPtys/Fixtures/known-persistent-pty-handoff.json" LogicalName="OpenCode.Sdk.Tests.Fixtures.Serialization.known-persistent-pty-handoff.json" />
+    <EmbeddedResource Include="PersistentPtys/Fixtures/known-persistent-pty-read.json" LogicalName="OpenCode.Sdk.Tests.Fixtures.Serialization.known-persistent-pty-read.json" />
+    <EmbeddedResource Include="PersistentPtys/Fixtures/known-persistent-pty-snapshot.json" LogicalName="OpenCode.Sdk.Tests.Fixtures.Serialization.known-persistent-pty-snapshot.json" />
+    <EmbeddedResource Include="PersistentPtys/Fixtures/known-persistent-pty.json" LogicalName="OpenCode.Sdk.Tests.Fixtures.Serialization.known-persistent-pty.json" />
+    <EmbeddedResource Include="Ptys/Fixtures/known-pty.json" LogicalName="OpenCode.Sdk.Tests.Fixtures.Serialization.known-pty.json" />
+    <EmbeddedResource Include="Serialization/Fixtures/known-rpc-event.json" LogicalName="OpenCode.Sdk.Tests.Fixtures.Serialization.known-rpc-event.json" />
+    <EmbeddedResource Include="Serialization/Fixtures/known-session-message-idle.json" LogicalName="OpenCode.Sdk.Tests.Fixtures.Serialization.known-session-message-idle.json" />
+    <EmbeddedResource Include="Sessions/Fixtures/known-session-stats.json" LogicalName="OpenCode.Sdk.Tests.Fixtures.Serialization.known-session-stats.json" />
+    <EmbeddedResource Include="Serialization/Fixtures/known-tool-state.json" LogicalName="OpenCode.Sdk.Tests.Fixtures.Serialization.known-tool-state.json" />
+    <EmbeddedResource Include="Websearch/Fixtures/known-websearch-response.json" LogicalName="OpenCode.Sdk.Tests.Fixtures.Serialization.known-websearch-response.json" />
+    <EmbeddedResource Include="Serialization/Fixtures/known-worktree-error.json" LogicalName="OpenCode.Sdk.Tests.Fixtures.Serialization.known-worktree-error.json" />
+    <EmbeddedResource Include="Serialization/Fixtures/long-unknown-session-message-marker.json" LogicalName="OpenCode.Sdk.Tests.Fixtures.Serialization.long-unknown-session-message-marker.json" />
+    <EmbeddedResource Include="Serialization/Fixtures/malformed-assistant-marker.json" LogicalName="OpenCode.Sdk.Tests.Fixtures.Serialization.malformed-assistant-marker.json" />
+    <EmbeddedResource Include="Serialization/Fixtures/mismatched-compaction-marker.json" LogicalName="OpenCode.Sdk.Tests.Fixtures.Serialization.mismatched-compaction-marker.json" />
+    <EmbeddedResource Include="Serialization/Fixtures/missing-assistant-marker.json" LogicalName="OpenCode.Sdk.Tests.Fixtures.Serialization.missing-assistant-marker.json" />
+    <EmbeddedResource Include="Serialization/Fixtures/non-object-union-payload.json" LogicalName="OpenCode.Sdk.Tests.Fixtures.Serialization.non-object-union-payload.json" />
+    <EmbeddedResource Include="Serialization/Fixtures/null-diff-status.json" LogicalName="OpenCode.Sdk.Tests.Fixtures.Serialization.null-diff-status.json" />
+    <EmbeddedResource Include="Serialization/Fixtures/null-optional-collection.json" LogicalName="OpenCode.Sdk.Tests.Fixtures.Serialization.null-optional-collection.json" />
+    <EmbeddedResource Include="Serialization/Fixtures/numeric-diff-status.json" LogicalName="OpenCode.Sdk.Tests.Fixtures.Serialization.numeric-diff-status.json" />
+    <EmbeddedResource Include="Sessions/Fixtures/numeric-status-session.json" LogicalName="OpenCode.Sdk.Tests.Fixtures.Serialization.numeric-status-session.json" />
+    <EmbeddedResource Include="Serialization/Fixtures/session-create-request-absent.json" LogicalName="OpenCode.Sdk.Tests.Fixtures.Serialization.session-create-request-absent.json" />
+    <EmbeddedResource Include="Serialization/Fixtures/session-create-request-cleared.json" LogicalName="OpenCode.Sdk.Tests.Fixtures.Serialization.session-create-request-cleared.json" />
+    <EmbeddedResource Include="Serialization/Fixtures/session-create-request-set.json" LogicalName="OpenCode.Sdk.Tests.Fixtures.Serialization.session-create-request-set.json" />
+    <EmbeddedResource Include="Serialization/Fixtures/stream-events.json" LogicalName="OpenCode.Sdk.Tests.Fixtures.Serialization.stream-events.json" />
+    <EmbeddedResource Include="Serialization/Fixtures/stream-session-messages.json" LogicalName="OpenCode.Sdk.Tests.Fixtures.Serialization.stream-session-messages.json" />
+    <EmbeddedResource Include="Serialization/Fixtures/unknown-assistant-content.json" LogicalName="OpenCode.Sdk.Tests.Fixtures.Serialization.unknown-assistant-content.json" />
+    <EmbeddedResource Include="Serialization/Fixtures/unknown-compaction-status.json" LogicalName="OpenCode.Sdk.Tests.Fixtures.Serialization.unknown-compaction-status.json" />
+    <EmbeddedResource Include="Serialization/Fixtures/unknown-config-entry.json" LogicalName="OpenCode.Sdk.Tests.Fixtures.Serialization.unknown-config-entry.json" />
+    <EmbeddedResource Include="Serialization/Fixtures/unknown-credential-value.json" LogicalName="OpenCode.Sdk.Tests.Fixtures.Serialization.unknown-credential-value.json" />
+    <EmbeddedResource Include="Serialization/Fixtures/unknown-diff-status.json" LogicalName="OpenCode.Sdk.Tests.Fixtures.Serialization.unknown-diff-status.json" />
+    <EmbeddedResource Include="Serialization/Fixtures/unknown-error-with-different-marker.json" LogicalName="OpenCode.Sdk.Tests.Fixtures.Serialization.unknown-error-with-different-marker.json" />
+    <EmbeddedResource Include="Serialization/Fixtures/unknown-error-without-marker.json" LogicalName="OpenCode.Sdk.Tests.Fixtures.Serialization.unknown-error-without-marker.json" />
+    <EmbeddedResource Include="Serialization/Fixtures/unknown-interrupted-reason-event.json" LogicalName="OpenCode.Sdk.Tests.Fixtures.Serialization.unknown-interrupted-reason-event.json" />
+    <EmbeddedResource Include="Serialization/Fixtures/unknown-mcp-oauth-token.json" LogicalName="OpenCode.Sdk.Tests.Fixtures.Serialization.unknown-mcp-oauth-token.json" />
+    <EmbeddedResource Include="Serialization/Fixtures/unknown-mcp-status.json" LogicalName="OpenCode.Sdk.Tests.Fixtures.Serialization.unknown-mcp-status.json" />
+    <EmbeddedResource Include="Serialization/Fixtures/unknown-mcp.json" LogicalName="OpenCode.Sdk.Tests.Fixtures.Serialization.unknown-mcp.json" />
+    <EmbeddedResource Include="Serialization/Fixtures/unknown-name-tagged-error.json" LogicalName="OpenCode.Sdk.Tests.Fixtures.Serialization.unknown-name-tagged-error.json" />
+    <EmbeddedResource Include="Serialization/Fixtures/unknown-session-message.json" LogicalName="OpenCode.Sdk.Tests.Fixtures.Serialization.unknown-session-message.json" />
+    <EmbeddedResource Include="Serialization/Fixtures/unknown-tool-state.json" LogicalName="OpenCode.Sdk.Tests.Fixtures.Serialization.unknown-tool-state.json" />
+    <EmbeddedResource Include="Serialization/Fixtures/worktree-error-null-force-required.json" LogicalName="OpenCode.Sdk.Tests.Fixtures.Serialization.worktree-error-null-force-required.json" />
+    <EmbeddedResource Include="Serialization/Fixtures/worktree-error-without-force-required.json" LogicalName="OpenCode.Sdk.Tests.Fixtures.Serialization.worktree-error-without-force-required.json" />
+    <EmbeddedResource Include="Hosting/Launcher/Fixtures/child-tree.js" LogicalName="OpenCode.Sdk.Tests.Fixtures.Server.child-tree.js" />
+    <EmbeddedResource Include="Harness/Fixtures/diagnostic-peer.js" LogicalName="OpenCode.Sdk.Tests.Fixtures.Server.diagnostic-peer.js" />
+    <EmbeddedResource Include="Harness/Fixtures/exited-diagnostic-peer.js" LogicalName="OpenCode.Sdk.Tests.Fixtures.Server.exited-diagnostic-peer.js" />
+    <EmbeddedResource Include="Hosting/Launcher/Fixtures/ladder-tree.js" LogicalName="OpenCode.Sdk.Tests.Fixtures.Server.ladder-tree.js" />
+    <EmbeddedResource Include="Harness/Fixtures/persistent-simulation-host.js" LogicalName="OpenCode.Sdk.Tests.Fixtures.Server.persistent-simulation-host.js" />
+    <EmbeddedResource Include="Hosting/Launcher/Fixtures/stdout-holder.js" LogicalName="OpenCode.Sdk.Tests.Fixtures.Server.stdout-holder.js" />
+    <EmbeddedResource Include="Sessions/Fixtures/drive-echo-tool.json" LogicalName="OpenCode.Sdk.Tests.Fixtures.Simulation.drive-echo-tool.json" />
+    <EmbeddedResource Include="Skills/Fixtures/sdk-live-skill.md" LogicalName="OpenCode.Sdk.Tests.Fixtures.Skills.sdk-live-skill.md" />
+    <EmbeddedResource Include="Serialization/Fixtures/first-match-corpus.json" LogicalName="OpenCode.Sdk.Tests.Fixtures.Unions.first-match-corpus.json" />
+    <EmbeddedResource Include="Serialization/Fixtures/first-match-expected.json" LogicalName="OpenCode.Sdk.Tests.Fixtures.Unions.first-match-expected.json" />
+  </ItemGroup>
+
 </Project>
diff --git a/tests/OpenCode.Sdk.Tests/Fixtures/Serialization/known-persistent-pty-handoff.json b/tests/OpenCode.Sdk.Tests/PersistentPtys/Fixtures/known-persistent-pty-handoff.json
similarity index 100%
rename from tests/OpenCode.Sdk.Tests/Fixtures/Serialization/known-persistent-pty-handoff.json
rename to tests/OpenCode.Sdk.Tests/PersistentPtys/Fixtures/known-persistent-pty-handoff.json
diff --git a/tests/OpenCode.Sdk.Tests/Fixtures/Serialization/known-persistent-pty-read.json b/tests/OpenCode.Sdk.Tests/PersistentPtys/Fixtures/known-persistent-pty-read.json
similarity index 100%
rename from tests/OpenCode.Sdk.Tests/Fixtures/Serialization/known-persistent-pty-read.json
rename to tests/OpenCode.Sdk.Tests/PersistentPtys/Fixtures/known-persistent-pty-read.json
diff --git a/tests/OpenCode.Sdk.Tests/Fixtures/Serialization/known-persistent-pty-snapshot.json b/tests/OpenCode.Sdk.Tests/PersistentPtys/Fixtures/known-persistent-pty-snapshot.json
similarity index 100%
rename from tests/OpenCode.Sdk.Tests/Fixtures/Serialization/known-persistent-pty-snapshot.json
rename to tests/OpenCode.Sdk.Tests/PersistentPtys/Fixtures/known-persistent-pty-snapshot.json
diff --git a/tests/OpenCode.Sdk.Tests/Fixtures/Serialization/known-persistent-pty.json b/tests/OpenCode.Sdk.Tests/PersistentPtys/Fixtures/known-persistent-pty.json
similarity index 100%
rename from tests/OpenCode.Sdk.Tests/Fixtures/Serialization/known-persistent-pty.json
rename to tests/OpenCode.Sdk.Tests/PersistentPtys/Fixtures/known-persistent-pty.json
diff --git a/tests/OpenCode.Sdk.Tests/Fixtures/Ptys/cursor-second-value.json b/tests/OpenCode.Sdk.Tests/Ptys/Fixtures/cursor-second-value.json
similarity index 100%
rename from tests/OpenCode.Sdk.Tests/Fixtures/Ptys/cursor-second-value.json
rename to tests/OpenCode.Sdk.Tests/Ptys/Fixtures/cursor-second-value.json
diff --git a/tests/OpenCode.Sdk.Tests/Fixtures/Ptys/cursor-trailing-garbage.json b/tests/OpenCode.Sdk.Tests/Ptys/Fixtures/cursor-trailing-garbage.json
similarity index 100%
rename from tests/OpenCode.Sdk.Tests/Fixtures/Ptys/cursor-trailing-garbage.json
rename to tests/OpenCode.Sdk.Tests/Ptys/Fixtures/cursor-trailing-garbage.json
diff --git a/tests/OpenCode.Sdk.Tests/Fixtures/Ptys/cursor-truncated-after-value.json b/tests/OpenCode.Sdk.Tests/Ptys/Fixtures/cursor-truncated-after-value.json
similarity index 100%
rename from tests/OpenCode.Sdk.Tests/Fixtures/Ptys/cursor-truncated-after-value.json
rename to tests/OpenCode.Sdk.Tests/Ptys/Fixtures/cursor-truncated-after-value.json
diff --git a/tests/OpenCode.Sdk.Tests/Fixtures/Ptys/cursor-valid-whitespace.json b/tests/OpenCode.Sdk.Tests/Ptys/Fixtures/cursor-valid-whitespace.json
similarity index 100%
rename from tests/OpenCode.Sdk.Tests/Fixtures/Ptys/cursor-valid-whitespace.json
rename to tests/OpenCode.Sdk.Tests/Ptys/Fixtures/cursor-valid-whitespace.json
diff --git a/tests/OpenCode.Sdk.Tests/Fixtures/Serialization/known-pty.json b/tests/OpenCode.Sdk.Tests/Ptys/Fixtures/known-pty.json
similarity index 100%
rename from tests/OpenCode.Sdk.Tests/Fixtures/Serialization/known-pty.json
rename to tests/OpenCode.Sdk.Tests/Ptys/Fixtures/known-pty.json
diff --git a/tests/OpenCode.Sdk.Tests/Fixtures/Ptys/terminal-peer.js b/tests/OpenCode.Sdk.Tests/Ptys/Fixtures/terminal-peer.js
similarity index 100%
rename from tests/OpenCode.Sdk.Tests/Fixtures/Ptys/terminal-peer.js
rename to tests/OpenCode.Sdk.Tests/Ptys/Fixtures/terminal-peer.js
diff --git a/tests/OpenCode.Sdk.Tests/Ptys/PtyFrameReaderTests.cs b/tests/OpenCode.Sdk.Tests/Ptys/PtyFrameReaderTests.cs
index 85bfd13e7..d890c92dc 100644
--- a/tests/OpenCode.Sdk.Tests/Ptys/PtyFrameReaderTests.cs
+++ b/tests/OpenCode.Sdk.Tests/Ptys/PtyFrameReaderTests.cs
@@ -1,7 +1,7 @@
 using System.Net.WebSockets;
 using OpenCode.Sdk.Internal;
 using OpenCode.Sdk.Tests.Harness;
-using OpenCode.Sdk.Tests.Support;
+using OpenCode.Sdk.Tests.Ptys.Support;
 
 namespace OpenCode.Sdk.Tests.Ptys;
 
diff --git a/tests/OpenCode.Sdk.Tests/Ptys/PtySessionLiveTests.cs b/tests/OpenCode.Sdk.Tests/Ptys/PtySessionLiveTests.cs
index 956924f31..08c99e6e5 100644
--- a/tests/OpenCode.Sdk.Tests/Ptys/PtySessionLiveTests.cs
+++ b/tests/OpenCode.Sdk.Tests/Ptys/PtySessionLiveTests.cs
@@ -2,7 +2,7 @@
 using OpenCode.Sdk.Internal;
 using OpenCode.Sdk.Models;
 using OpenCode.Sdk.Tests.Harness;
-using OpenCode.Sdk.Tests.Support;
+using OpenCode.Sdk.Tests.Ptys.Support;
 
 namespace OpenCode.Sdk.Tests.Ptys;
 
diff --git a/tests/OpenCode.Sdk.Tests/Ptys/PtySessionTests.cs b/tests/OpenCode.Sdk.Tests/Ptys/PtySessionTests.cs
index ad0b16d98..a0694da6a 100644
--- a/tests/OpenCode.Sdk.Tests/Ptys/PtySessionTests.cs
+++ b/tests/OpenCode.Sdk.Tests/Ptys/PtySessionTests.cs
@@ -1,6 +1,7 @@
 using System.Net.WebSockets;
 using System.Text;
 using OpenCode.Sdk.Internal;
+using OpenCode.Sdk.Tests.Ptys.Support;
 using OpenCode.Sdk.Tests.Support;
 
 namespace OpenCode.Sdk.Tests.Ptys;
diff --git a/tests/OpenCode.Sdk.Tests/Support/PtyDiagnosticServer.cs b/tests/OpenCode.Sdk.Tests/Ptys/Support/PtyDiagnosticServer.cs
similarity index 95%
rename from tests/OpenCode.Sdk.Tests/Support/PtyDiagnosticServer.cs
rename to tests/OpenCode.Sdk.Tests/Ptys/Support/PtyDiagnosticServer.cs
index 72855d142..51ff137b8 100644
--- a/tests/OpenCode.Sdk.Tests/Support/PtyDiagnosticServer.cs
+++ b/tests/OpenCode.Sdk.Tests/Ptys/Support/PtyDiagnosticServer.cs
@@ -1,7 +1,8 @@
 using System.Net;
 using OpenCode.Sdk.Tests.Harness;
+using OpenCode.Sdk.Tests.Support;
 
-namespace OpenCode.Sdk.Tests.Support;
+namespace OpenCode.Sdk.Tests.Ptys.Support;
 
 /// <summary>Serves a healthy external endpoint with either a completed or stalled typed PTY response.</summary>
 internal sealed class PtyDiagnosticServer : IAsyncDisposable
diff --git a/tests/OpenCode.Sdk.Tests/Support/PtyFailureDiagnostics.cs b/tests/OpenCode.Sdk.Tests/Ptys/Support/PtyFailureDiagnostics.cs
similarity index 98%
rename from tests/OpenCode.Sdk.Tests/Support/PtyFailureDiagnostics.cs
rename to tests/OpenCode.Sdk.Tests/Ptys/Support/PtyFailureDiagnostics.cs
index 41e69f65d..ef47aeb25 100644
--- a/tests/OpenCode.Sdk.Tests/Support/PtyFailureDiagnostics.cs
+++ b/tests/OpenCode.Sdk.Tests/Ptys/Support/PtyFailureDiagnostics.cs
@@ -3,7 +3,7 @@
 using OpenCode.Sdk.Tests.Harness.Ownership;
 using OpenCode.Sdk.Tests.Harness.Ownership.Abstractions;
 
-namespace OpenCode.Sdk.Tests.Support;
+namespace OpenCode.Sdk.Tests.Ptys.Support;
 
 internal sealed class PtyFailureDiagnostics(IOwnedOperationDeadline? deadline = null)
 {
diff --git a/tests/OpenCode.Sdk.Tests/Support/PtyFailureDiagnosticsTests.cs b/tests/OpenCode.Sdk.Tests/Ptys/Support/PtyFailureDiagnosticsTests.cs
similarity index 97%
rename from tests/OpenCode.Sdk.Tests/Support/PtyFailureDiagnosticsTests.cs
rename to tests/OpenCode.Sdk.Tests/Ptys/Support/PtyFailureDiagnosticsTests.cs
index fea537747..6c6945a68 100644
--- a/tests/OpenCode.Sdk.Tests/Support/PtyFailureDiagnosticsTests.cs
+++ b/tests/OpenCode.Sdk.Tests/Ptys/Support/PtyFailureDiagnosticsTests.cs
@@ -1,9 +1,10 @@
 using OpenCode.Sdk.Internal;
 using OpenCode.Sdk.Tests.Harness;
 using OpenCode.Sdk.Tests.Harness.Ownership;
+using OpenCode.Sdk.Tests.Support;
 using Testably.Abstractions;
 
-namespace OpenCode.Sdk.Tests.Support;
+namespace OpenCode.Sdk.Tests.Ptys.Support;
 
 [NotInParallel(ParallelConstraintKeys.ServerProcess)]
 public sealed class PtyFailureDiagnosticsTests
diff --git a/tests/OpenCode.Sdk.Tests/Support/PtyFrameData.cs b/tests/OpenCode.Sdk.Tests/Ptys/Support/PtyFrameData.cs
similarity index 97%
rename from tests/OpenCode.Sdk.Tests/Support/PtyFrameData.cs
rename to tests/OpenCode.Sdk.Tests/Ptys/Support/PtyFrameData.cs
index 280a64d14..d37186977 100644
--- a/tests/OpenCode.Sdk.Tests/Support/PtyFrameData.cs
+++ b/tests/OpenCode.Sdk.Tests/Ptys/Support/PtyFrameData.cs
@@ -1,6 +1,6 @@
 using System.Text;
 
-namespace OpenCode.Sdk.Tests.Support;
+namespace OpenCode.Sdk.Tests.Ptys.Support;
 
 /// <summary>
 /// The PTY wire literals the session tests run on. The control frame's exact byte shape — a
diff --git a/tests/OpenCode.Sdk.Tests/Support/PtyLiveScenario.cs b/tests/OpenCode.Sdk.Tests/Ptys/Support/PtyLiveScenario.cs
similarity index 99%
rename from tests/OpenCode.Sdk.Tests/Support/PtyLiveScenario.cs
rename to tests/OpenCode.Sdk.Tests/Ptys/Support/PtyLiveScenario.cs
index c1fdf2c14..c3e107adf 100644
--- a/tests/OpenCode.Sdk.Tests/Support/PtyLiveScenario.cs
+++ b/tests/OpenCode.Sdk.Tests/Ptys/Support/PtyLiveScenario.cs
@@ -4,7 +4,7 @@
 using OpenCode.Sdk.Tests.Harness;
 using OpenCode.Sdk.Tests.Harness.Ownership;
 
-namespace OpenCode.Sdk.Tests.Support;
+namespace OpenCode.Sdk.Tests.Ptys.Support;
 
 /// <summary>
 /// Owns the normal PTY live test's server-relative location and cleanup. External mode resolves
diff --git a/tests/OpenCode.Sdk.Tests/Support/PtyLiveTranscript.cs b/tests/OpenCode.Sdk.Tests/Ptys/Support/PtyLiveTranscript.cs
similarity index 99%
rename from tests/OpenCode.Sdk.Tests/Support/PtyLiveTranscript.cs
rename to tests/OpenCode.Sdk.Tests/Ptys/Support/PtyLiveTranscript.cs
index 950cb768e..b4d0d9872 100644
--- a/tests/OpenCode.Sdk.Tests/Support/PtyLiveTranscript.cs
+++ b/tests/OpenCode.Sdk.Tests/Ptys/Support/PtyLiveTranscript.cs
@@ -1,7 +1,7 @@
 using System.Globalization;
 using System.Text;
 
-namespace OpenCode.Sdk.Tests.Support;
+namespace OpenCode.Sdk.Tests.Ptys.Support;
 
 /// <summary>
 /// Observes one live PTY connection as complete newline-delimited records and server cursor
diff --git a/tests/OpenCode.Sdk.Tests/Fixtures/Rpc/rpc-call-input.json b/tests/OpenCode.Sdk.Tests/Rpc/Fixtures/rpc-call-input.json
similarity index 100%
rename from tests/OpenCode.Sdk.Tests/Fixtures/Rpc/rpc-call-input.json
rename to tests/OpenCode.Sdk.Tests/Rpc/Fixtures/rpc-call-input.json
diff --git a/tests/OpenCode.Sdk.Tests/ExtensibleEnumContractTests.cs b/tests/OpenCode.Sdk.Tests/Serialization/ExtensibleEnumContractTests.cs
similarity index 99%
rename from tests/OpenCode.Sdk.Tests/ExtensibleEnumContractTests.cs
rename to tests/OpenCode.Sdk.Tests/Serialization/ExtensibleEnumContractTests.cs
index a2d433a20..f41ef01ef 100644
--- a/tests/OpenCode.Sdk.Tests/ExtensibleEnumContractTests.cs
+++ b/tests/OpenCode.Sdk.Tests/Serialization/ExtensibleEnumContractTests.cs
@@ -3,7 +3,7 @@
 using OpenCode.Sdk.Models;
 using OpenCode.Sdk.Tests.Harness;
 
-namespace OpenCode.Sdk.Tests;
+namespace OpenCode.Sdk.Tests.Serialization;
 
 /// <summary>
 /// The generated string enums are extensible: a value a newer server sends is kept as it
diff --git a/tests/OpenCode.Sdk.Tests/Fixtures/Serialization/duplicate-known-session-message-marker.json b/tests/OpenCode.Sdk.Tests/Serialization/Fixtures/duplicate-known-session-message-marker.json
similarity index 100%
rename from tests/OpenCode.Sdk.Tests/Fixtures/Serialization/duplicate-known-session-message-marker.json
rename to tests/OpenCode.Sdk.Tests/Serialization/Fixtures/duplicate-known-session-message-marker.json
diff --git a/tests/OpenCode.Sdk.Tests/Fixtures/Serialization/duplicate-unknown-session-message-marker.json b/tests/OpenCode.Sdk.Tests/Serialization/Fixtures/duplicate-unknown-session-message-marker.json
similarity index 100%
rename from tests/OpenCode.Sdk.Tests/Fixtures/Serialization/duplicate-unknown-session-message-marker.json
rename to tests/OpenCode.Sdk.Tests/Serialization/Fixtures/duplicate-unknown-session-message-marker.json
diff --git a/tests/OpenCode.Sdk.Tests/Fixtures/Serialization/empty-assistant-marker.json b/tests/OpenCode.Sdk.Tests/Serialization/Fixtures/empty-assistant-marker.json
similarity index 100%
rename from tests/OpenCode.Sdk.Tests/Fixtures/Serialization/empty-assistant-marker.json
rename to tests/OpenCode.Sdk.Tests/Serialization/Fixtures/empty-assistant-marker.json
diff --git a/tests/OpenCode.Sdk.Tests/Fixtures/Serialization/error-carrying-both-markers.json b/tests/OpenCode.Sdk.Tests/Serialization/Fixtures/error-carrying-both-markers.json
similarity index 100%
rename from tests/OpenCode.Sdk.Tests/Fixtures/Serialization/error-carrying-both-markers.json
rename to tests/OpenCode.Sdk.Tests/Serialization/Fixtures/error-carrying-both-markers.json
diff --git a/tests/OpenCode.Sdk.Tests/Fixtures/Unions/first-match-corpus.json b/tests/OpenCode.Sdk.Tests/Serialization/Fixtures/first-match-corpus.json
similarity index 100%
rename from tests/OpenCode.Sdk.Tests/Fixtures/Unions/first-match-corpus.json
rename to tests/OpenCode.Sdk.Tests/Serialization/Fixtures/first-match-corpus.json
diff --git a/tests/OpenCode.Sdk.Tests/Fixtures/Unions/first-match-expected.json b/tests/OpenCode.Sdk.Tests/Serialization/Fixtures/first-match-expected.json
similarity index 100%
rename from tests/OpenCode.Sdk.Tests/Fixtures/Unions/first-match-expected.json
rename to tests/OpenCode.Sdk.Tests/Serialization/Fixtures/first-match-expected.json
diff --git a/tests/OpenCode.Sdk.Tests/Fixtures/Serialization/known-assistant-content.json b/tests/OpenCode.Sdk.Tests/Serialization/Fixtures/known-assistant-content.json
similarity index 100%
rename from tests/OpenCode.Sdk.Tests/Fixtures/Serialization/known-assistant-content.json
rename to tests/OpenCode.Sdk.Tests/Serialization/Fixtures/known-assistant-content.json
diff --git a/tests/OpenCode.Sdk.Tests/Fixtures/Serialization/known-compaction-message.json b/tests/OpenCode.Sdk.Tests/Serialization/Fixtures/known-compaction-message.json
similarity index 100%
rename from tests/OpenCode.Sdk.Tests/Fixtures/Serialization/known-compaction-message.json
rename to tests/OpenCode.Sdk.Tests/Serialization/Fixtures/known-compaction-message.json
diff --git a/tests/OpenCode.Sdk.Tests/Fixtures/Serialization/known-rpc-event.json b/tests/OpenCode.Sdk.Tests/Serialization/Fixtures/known-rpc-event.json
similarity index 100%
rename from tests/OpenCode.Sdk.Tests/Fixtures/Serialization/known-rpc-event.json
rename to tests/OpenCode.Sdk.Tests/Serialization/Fixtures/known-rpc-event.json
diff --git a/tests/OpenCode.Sdk.Tests/Fixtures/Serialization/known-session-message-idle.json b/tests/OpenCode.Sdk.Tests/Serialization/Fixtures/known-session-message-idle.json
similarity index 100%
rename from tests/OpenCode.Sdk.Tests/Fixtures/Serialization/known-session-message-idle.json
rename to tests/OpenCode.Sdk.Tests/Serialization/Fixtures/known-session-message-idle.json
diff --git a/tests/OpenCode.Sdk.Tests/Fixtures/Serialization/known-tool-state.json b/tests/OpenCode.Sdk.Tests/Serialization/Fixtures/known-tool-state.json
similarity index 100%
rename from tests/OpenCode.Sdk.Tests/Fixtures/Serialization/known-tool-state.json
rename to tests/OpenCode.Sdk.Tests/Serialization/Fixtures/known-tool-state.json
diff --git a/tests/OpenCode.Sdk.Tests/Fixtures/Serialization/known-worktree-error.json b/tests/OpenCode.Sdk.Tests/Serialization/Fixtures/known-worktree-error.json
similarity index 100%
rename from tests/OpenCode.Sdk.Tests/Fixtures/Serialization/known-worktree-error.json
rename to tests/OpenCode.Sdk.Tests/Serialization/Fixtures/known-worktree-error.json
diff --git a/tests/OpenCode.Sdk.Tests/Fixtures/Serialization/long-unknown-session-message-marker.json b/tests/OpenCode.Sdk.Tests/Serialization/Fixtures/long-unknown-session-message-marker.json
similarity index 100%
rename from tests/OpenCode.Sdk.Tests/Fixtures/Serialization/long-unknown-session-message-marker.json
rename to tests/OpenCode.Sdk.Tests/Serialization/Fixtures/long-unknown-session-message-marker.json
diff --git a/tests/OpenCode.Sdk.Tests/Fixtures/Serialization/malformed-assistant-marker.json b/tests/OpenCode.Sdk.Tests/Serialization/Fixtures/malformed-assistant-marker.json
similarity index 100%
rename from tests/OpenCode.Sdk.Tests/Fixtures/Serialization/malformed-assistant-marker.json
rename to tests/OpenCode.Sdk.Tests/Serialization/Fixtures/malformed-assistant-marker.json
diff --git a/tests/OpenCode.Sdk.Tests/Fixtures/Serialization/mismatched-compaction-marker.json b/tests/OpenCode.Sdk.Tests/Serialization/Fixtures/mismatched-compaction-marker.json
similarity index 100%
rename from tests/OpenCode.Sdk.Tests/Fixtures/Serialization/mismatched-compaction-marker.json
rename to tests/OpenCode.Sdk.Tests/Serialization/Fixtures/mismatched-compaction-marker.json
diff --git a/tests/OpenCode.Sdk.Tests/Fixtures/Serialization/missing-assistant-marker.json b/tests/OpenCode.Sdk.Tests/Serialization/Fixtures/missing-assistant-marker.json
similarity index 100%
rename from tests/OpenCode.Sdk.Tests/Fixtures/Serialization/missing-assistant-marker.json
rename to tests/OpenCode.Sdk.Tests/Serialization/Fixtures/missing-assistant-marker.json
diff --git a/tests/OpenCode.Sdk.Tests/Fixtures/Serialization/non-object-union-payload.json b/tests/OpenCode.Sdk.Tests/Serialization/Fixtures/non-object-union-payload.json
similarity index 100%
rename from tests/OpenCode.Sdk.Tests/Fixtures/Serialization/non-object-union-payload.json
rename to tests/OpenCode.Sdk.Tests/Serialization/Fixtures/non-object-union-payload.json
diff --git a/tests/OpenCode.Sdk.Tests/Fixtures/Serialization/null-diff-status.json b/tests/OpenCode.Sdk.Tests/Serialization/Fixtures/null-diff-status.json
similarity index 100%
rename from tests/OpenCode.Sdk.Tests/Fixtures/Serialization/null-diff-status.json
rename to tests/OpenCode.Sdk.Tests/Serialization/Fixtures/null-diff-status.json
diff --git a/tests/OpenCode.Sdk.Tests/Fixtures/Serialization/null-optional-collection.json b/tests/OpenCode.Sdk.Tests/Serialization/Fixtures/null-optional-collection.json
similarity index 100%
rename from tests/OpenCode.Sdk.Tests/Fixtures/Serialization/null-optional-collection.json
rename to tests/OpenCode.Sdk.Tests/Serialization/Fixtures/null-optional-collection.json
diff --git a/tests/OpenCode.Sdk.Tests/Fixtures/Serialization/numeric-diff-status.json b/tests/OpenCode.Sdk.Tests/Serialization/Fixtures/numeric-diff-status.json
similarity index 100%
rename from tests/OpenCode.Sdk.Tests/Fixtures/Serialization/numeric-diff-status.json
rename to tests/OpenCode.Sdk.Tests/Serialization/Fixtures/numeric-diff-status.json
diff --git a/tests/OpenCode.Sdk.Tests/Fixtures/Serialization/session-create-request-absent.json b/tests/OpenCode.Sdk.Tests/Serialization/Fixtures/session-create-request-absent.json
similarity index 100%
rename from tests/OpenCode.Sdk.Tests/Fixtures/Serialization/session-create-request-absent.json
rename to tests/OpenCode.Sdk.Tests/Serialization/Fixtures/session-create-request-absent.json
diff --git a/tests/OpenCode.Sdk.Tests/Fixtures/Serialization/session-create-request-cleared.json b/tests/OpenCode.Sdk.Tests/Serialization/Fixtures/session-create-request-cleared.json
similarity index 100%
rename from tests/OpenCode.Sdk.Tests/Fixtures/Serialization/session-create-request-cleared.json
rename to tests/OpenCode.Sdk.Tests/Serialization/Fixtures/session-create-request-cleared.json
diff --git a/tests/OpenCode.Sdk.Tests/Fixtures/Serialization/session-create-request-set.json b/tests/OpenCode.Sdk.Tests/Serialization/Fixtures/session-create-request-set.json
similarity index 100%
rename from tests/OpenCode.Sdk.Tests/Fixtures/Serialization/session-create-request-set.json
rename to tests/OpenCode.Sdk.Tests/Serialization/Fixtures/session-create-request-set.json
diff --git a/tests/OpenCode.Sdk.Tests/Fixtures/Serialization/stream-events.json b/tests/OpenCode.Sdk.Tests/Serialization/Fixtures/stream-events.json
similarity index 100%
rename from tests/OpenCode.Sdk.Tests/Fixtures/Serialization/stream-events.json
rename to tests/OpenCode.Sdk.Tests/Serialization/Fixtures/stream-events.json
diff --git a/tests/OpenCode.Sdk.Tests/Fixtures/Serialization/stream-session-messages.json b/tests/OpenCode.Sdk.Tests/Serialization/Fixtures/stream-session-messages.json
similarity index 100%
rename from tests/OpenCode.Sdk.Tests/Fixtures/Serialization/stream-session-messages.json
rename to tests/OpenCode.Sdk.Tests/Serialization/Fixtures/stream-session-messages.json
diff --git a/tests/OpenCode.Sdk.Tests/Fixtures/Serialization/unknown-assistant-content.json b/tests/OpenCode.Sdk.Tests/Serialization/Fixtures/unknown-assistant-content.json
similarity index 100%
rename from tests/OpenCode.Sdk.Tests/Fixtures/Serialization/unknown-assistant-content.json
rename to tests/OpenCode.Sdk.Tests/Serialization/Fixtures/unknown-assistant-content.json
diff --git a/tests/OpenCode.Sdk.Tests/Fixtures/Serialization/unknown-compaction-status.json b/tests/OpenCode.Sdk.Tests/Serialization/Fixtures/unknown-compaction-status.json
similarity index 100%
rename from tests/OpenCode.Sdk.Tests/Fixtures/Serialization/unknown-compaction-status.json
rename to tests/OpenCode.Sdk.Tests/Serialization/Fixtures/unknown-compaction-status.json
diff --git a/tests/OpenCode.Sdk.Tests/Fixtures/Serialization/unknown-config-entry.json b/tests/OpenCode.Sdk.Tests/Serialization/Fixtures/unknown-config-entry.json
similarity index 100%
rename from tests/OpenCode.Sdk.Tests/Fixtures/Serialization/unknown-config-entry.json
rename to tests/OpenCode.Sdk.Tests/Serialization/Fixtures/unknown-config-entry.json
diff --git a/tests/OpenCode.Sdk.Tests/Fixtures/Serialization/unknown-credential-value.json b/tests/OpenCode.Sdk.Tests/Serialization/Fixtures/unknown-credential-value.json
similarity index 100%
rename from tests/OpenCode.Sdk.Tests/Fixtures/Serialization/unknown-credential-value.json
rename to tests/OpenCode.Sdk.Tests/Serialization/Fixtures/unknown-credential-value.json
diff --git a/tests/OpenCode.Sdk.Tests/Fixtures/Serialization/unknown-diff-status.json b/tests/OpenCode.Sdk.Tests/Serialization/Fixtures/unknown-diff-status.json
similarity index 100%
rename from tests/OpenCode.Sdk.Tests/Fixtures/Serialization/unknown-diff-status.json
rename to tests/OpenCode.Sdk.Tests/Serialization/Fixtures/unknown-diff-status.json
diff --git a/tests/OpenCode.Sdk.Tests/Fixtures/Serialization/unknown-error-with-different-marker.json b/tests/OpenCode.Sdk.Tests/Serialization/Fixtures/unknown-error-with-different-marker.json
similarity index 100%
rename from tests/OpenCode.Sdk.Tests/Fixtures/Serialization/unknown-error-with-different-marker.json
rename to tests/OpenCode.Sdk.Tests/Serialization/Fixtures/unknown-error-with-different-marker.json
diff --git a/tests/OpenCode.Sdk.Tests/Fixtures/Serialization/unknown-error-without-marker.json b/tests/OpenCode.Sdk.Tests/Serialization/Fixtures/unknown-error-without-marker.json
similarity index 100%
rename from tests/OpenCode.Sdk.Tests/Fixtures/Serialization/unknown-error-without-marker.json
rename to tests/OpenCode.Sdk.Tests/Serialization/Fixtures/unknown-error-without-marker.json
diff --git a/tests/OpenCode.Sdk.Tests/Fixtures/Serialization/unknown-interrupted-reason-event.json b/tests/OpenCode.Sdk.Tests/Serialization/Fixtures/unknown-interrupted-reason-event.json
similarity index 100%
rename from tests/OpenCode.Sdk.Tests/Fixtures/Serialization/unknown-interrupted-reason-event.json
rename to tests/OpenCode.Sdk.Tests/Serialization/Fixtures/unknown-interrupted-reason-event.json
diff --git a/tests/OpenCode.Sdk.Tests/Fixtures/Serialization/unknown-mcp-oauth-token.json b/tests/OpenCode.Sdk.Tests/Serialization/Fixtures/unknown-mcp-oauth-token.json
similarity index 100%
rename from tests/OpenCode.Sdk.Tests/Fixtures/Serialization/unknown-mcp-oauth-token.json
rename to tests/OpenCode.Sdk.Tests/Serialization/Fixtures/unknown-mcp-oauth-token.json
diff --git a/tests/OpenCode.Sdk.Tests/Fixtures/Serialization/unknown-mcp-status.json b/tests/OpenCode.Sdk.Tests/Serialization/Fixtures/unknown-mcp-status.json
similarity index 100%
rename from tests/OpenCode.Sdk.Tests/Fixtures/Serialization/unknown-mcp-status.json
rename to tests/OpenCode.Sdk.Tests/Serialization/Fixtures/unknown-mcp-status.json
diff --git a/tests/OpenCode.Sdk.Tests/Fixtures/Serialization/unknown-mcp.json b/tests/OpenCode.Sdk.Tests/Serialization/Fixtures/unknown-mcp.json
similarity index 100%
rename from tests/OpenCode.Sdk.Tests/Fixtures/Serialization/unknown-mcp.json
rename to tests/OpenCode.Sdk.Tests/Serialization/Fixtures/unknown-mcp.json
diff --git a/tests/OpenCode.Sdk.Tests/Fixtures/Serialization/unknown-name-tagged-error.json b/tests/OpenCode.Sdk.Tests/Serialization/Fixtures/unknown-name-tagged-error.json
similarity index 100%
rename from tests/OpenCode.Sdk.Tests/Fixtures/Serialization/unknown-name-tagged-error.json
rename to tests/OpenCode.Sdk.Tests/Serialization/Fixtures/unknown-name-tagged-error.json
diff --git a/tests/OpenCode.Sdk.Tests/Fixtures/Serialization/unknown-session-message.json b/tests/OpenCode.Sdk.Tests/Serialization/Fixtures/unknown-session-message.json
similarity index 100%
rename from tests/OpenCode.Sdk.Tests/Fixtures/Serialization/unknown-session-message.json
rename to tests/OpenCode.Sdk.Tests/Serialization/Fixtures/unknown-session-message.json
diff --git a/tests/OpenCode.Sdk.Tests/Fixtures/Serialization/unknown-tool-state.json b/tests/OpenCode.Sdk.Tests/Serialization/Fixtures/unknown-tool-state.json
similarity index 100%
rename from tests/OpenCode.Sdk.Tests/Fixtures/Serialization/unknown-tool-state.json
rename to tests/OpenCode.Sdk.Tests/Serialization/Fixtures/unknown-tool-state.json
diff --git a/tests/OpenCode.Sdk.Tests/Fixtures/Serialization/worktree-error-null-force-required.json b/tests/OpenCode.Sdk.Tests/Serialization/Fixtures/worktree-error-null-force-required.json
similarity index 100%
rename from tests/OpenCode.Sdk.Tests/Fixtures/Serialization/worktree-error-null-force-required.json
rename to tests/OpenCode.Sdk.Tests/Serialization/Fixtures/worktree-error-null-force-required.json
diff --git a/tests/OpenCode.Sdk.Tests/Fixtures/Serialization/worktree-error-without-force-required.json b/tests/OpenCode.Sdk.Tests/Serialization/Fixtures/worktree-error-without-force-required.json
similarity index 100%
rename from tests/OpenCode.Sdk.Tests/Fixtures/Serialization/worktree-error-without-force-required.json
rename to tests/OpenCode.Sdk.Tests/Serialization/Fixtures/worktree-error-without-force-required.json
diff --git a/tests/OpenCode.Sdk.Tests/SecretMemberPrintingTests.cs b/tests/OpenCode.Sdk.Tests/Serialization/SecretMemberPrintingTests.cs
similarity index 99%
rename from tests/OpenCode.Sdk.Tests/SecretMemberPrintingTests.cs
rename to tests/OpenCode.Sdk.Tests/Serialization/SecretMemberPrintingTests.cs
index 66592a2fd..f9ff5b2f8 100644
--- a/tests/OpenCode.Sdk.Tests/SecretMemberPrintingTests.cs
+++ b/tests/OpenCode.Sdk.Tests/Serialization/SecretMemberPrintingTests.cs
@@ -4,7 +4,7 @@
 using OpenCode.Sdk.Models;
 using OpenCode.Sdk.Tests.Harness;
 
-namespace OpenCode.Sdk.Tests;
+namespace OpenCode.Sdk.Tests.Serialization;
 
 /// <summary>
 /// A generated model whose member upstream's HTTP recorder redacts, or a curation row marks,
diff --git a/tests/OpenCode.Sdk.Tests/StructuralUnionFirstMatchParityTests.cs b/tests/OpenCode.Sdk.Tests/Serialization/StructuralUnionFirstMatchParityTests.cs
similarity index 98%
rename from tests/OpenCode.Sdk.Tests/StructuralUnionFirstMatchParityTests.cs
rename to tests/OpenCode.Sdk.Tests/Serialization/StructuralUnionFirstMatchParityTests.cs
index 9d332ff8a..c2ebfda6c 100644
--- a/tests/OpenCode.Sdk.Tests/StructuralUnionFirstMatchParityTests.cs
+++ b/tests/OpenCode.Sdk.Tests/Serialization/StructuralUnionFirstMatchParityTests.cs
@@ -4,7 +4,7 @@
 using OpenCode.Sdk.Models;
 using OpenCode.Sdk.Tests.Harness;
 
-namespace OpenCode.Sdk.Tests;
+namespace OpenCode.Sdk.Tests.Serialization;
 
 /// <summary>
 /// Upstream decodes the three same-token unions with Effect's union decode: the first member in
diff --git a/tests/OpenCode.Sdk.Tests/StructuralUnionPrintingTests.cs b/tests/OpenCode.Sdk.Tests/Serialization/StructuralUnionPrintingTests.cs
similarity index 98%
rename from tests/OpenCode.Sdk.Tests/StructuralUnionPrintingTests.cs
rename to tests/OpenCode.Sdk.Tests/Serialization/StructuralUnionPrintingTests.cs
index 1f9dfe1c2..56bfbe0ae 100644
--- a/tests/OpenCode.Sdk.Tests/StructuralUnionPrintingTests.cs
+++ b/tests/OpenCode.Sdk.Tests/Serialization/StructuralUnionPrintingTests.cs
@@ -3,7 +3,7 @@
 using OpenCode.Sdk.Internal;
 using OpenCode.Sdk.Models;
 
-namespace OpenCode.Sdk.Tests;
+namespace OpenCode.Sdk.Tests.Serialization;
 
 /// <summary>
 /// A structural union is a record whose inactive arm properties throw by design, so the
diff --git a/tests/OpenCode.Sdk.Tests/Fixtures/Simulation/drive-echo-tool.json b/tests/OpenCode.Sdk.Tests/Sessions/Fixtures/drive-echo-tool.json
similarity index 100%
rename from tests/OpenCode.Sdk.Tests/Fixtures/Simulation/drive-echo-tool.json
rename to tests/OpenCode.Sdk.Tests/Sessions/Fixtures/drive-echo-tool.json
diff --git a/tests/OpenCode.Sdk.Tests/Fixtures/Serialization/known-inbox-compaction.json b/tests/OpenCode.Sdk.Tests/Sessions/Fixtures/known-inbox-compaction.json
similarity index 100%
rename from tests/OpenCode.Sdk.Tests/Fixtures/Serialization/known-inbox-compaction.json
rename to tests/OpenCode.Sdk.Tests/Sessions/Fixtures/known-inbox-compaction.json
diff --git a/tests/OpenCode.Sdk.Tests/Fixtures/Serialization/known-permission.json b/tests/OpenCode.Sdk.Tests/Sessions/Fixtures/known-permission.json
similarity index 100%
rename from tests/OpenCode.Sdk.Tests/Fixtures/Serialization/known-permission.json
rename to tests/OpenCode.Sdk.Tests/Sessions/Fixtures/known-permission.json
diff --git a/tests/OpenCode.Sdk.Tests/Fixtures/Serialization/known-session-stats.json b/tests/OpenCode.Sdk.Tests/Sessions/Fixtures/known-session-stats.json
similarity index 100%
rename from tests/OpenCode.Sdk.Tests/Fixtures/Serialization/known-session-stats.json
rename to tests/OpenCode.Sdk.Tests/Sessions/Fixtures/known-session-stats.json
diff --git a/tests/OpenCode.Sdk.Tests/Fixtures/Serialization/numeric-status-session.json b/tests/OpenCode.Sdk.Tests/Sessions/Fixtures/numeric-status-session.json
similarity index 100%
rename from tests/OpenCode.Sdk.Tests/Fixtures/Serialization/numeric-status-session.json
rename to tests/OpenCode.Sdk.Tests/Sessions/Fixtures/numeric-status-session.json
diff --git a/tests/OpenCode.Sdk.Tests/Sessions/GettingStartedRecipeLiveTests.cs b/tests/OpenCode.Sdk.Tests/Sessions/GettingStartedRecipeLiveTests.cs
index 0c2496f2f..50c1b3d50 100644
--- a/tests/OpenCode.Sdk.Tests/Sessions/GettingStartedRecipeLiveTests.cs
+++ b/tests/OpenCode.Sdk.Tests/Sessions/GettingStartedRecipeLiveTests.cs
@@ -1,6 +1,6 @@
 using OpenCode.Sdk.Models;
 using OpenCode.Sdk.Tests.Harness;
-using OpenCode.Sdk.Tests.Support;
+using OpenCode.Sdk.Tests.Sessions.Support;
 
 namespace OpenCode.Sdk.Tests.Sessions;
 
diff --git a/tests/OpenCode.Sdk.Tests/Sessions/SessionClientLiveTests.cs b/tests/OpenCode.Sdk.Tests/Sessions/SessionClientLiveTests.cs
index 1a086e746..b83609137 100644
--- a/tests/OpenCode.Sdk.Tests/Sessions/SessionClientLiveTests.cs
+++ b/tests/OpenCode.Sdk.Tests/Sessions/SessionClientLiveTests.cs
@@ -1,6 +1,7 @@
 using System.Globalization;
 using OpenCode.Sdk.Models;
 using OpenCode.Sdk.Tests.Harness;
+using OpenCode.Sdk.Tests.Sessions.Support;
 using OpenCode.Sdk.Tests.Support;
 using Testably.Abstractions;
 
diff --git a/tests/OpenCode.Sdk.Tests/Sessions/SessionContextLiveTests.cs b/tests/OpenCode.Sdk.Tests/Sessions/SessionContextLiveTests.cs
index 191d42467..2e0dac13f 100644
--- a/tests/OpenCode.Sdk.Tests/Sessions/SessionContextLiveTests.cs
+++ b/tests/OpenCode.Sdk.Tests/Sessions/SessionContextLiveTests.cs
@@ -2,6 +2,7 @@
 using OpenCode.Sdk.Models;
 using OpenCode.Sdk.Tests.Harness;
 using OpenCode.Sdk.Tests.Harness.Ownership;
+using OpenCode.Sdk.Tests.Sessions.Support;
 using OpenCode.Sdk.Tests.Support;
 using TUnit.Assertions.Enums;
 
diff --git a/tests/OpenCode.Sdk.Tests/Sessions/SessionDiffLiveTests.cs b/tests/OpenCode.Sdk.Tests/Sessions/SessionDiffLiveTests.cs
index d5e06c8bf..ef1f48dfd 100644
--- a/tests/OpenCode.Sdk.Tests/Sessions/SessionDiffLiveTests.cs
+++ b/tests/OpenCode.Sdk.Tests/Sessions/SessionDiffLiveTests.cs
@@ -1,6 +1,7 @@
 using System.Globalization;
 using OpenCode.Sdk.Models;
 using OpenCode.Sdk.Tests.Harness;
+using OpenCode.Sdk.Tests.Sessions.Support;
 using OpenCode.Sdk.Tests.Support;
 using TUnit.Assertions.Enums;
 
diff --git a/tests/OpenCode.Sdk.Tests/Sessions/SessionInboxLiveTests.cs b/tests/OpenCode.Sdk.Tests/Sessions/SessionInboxLiveTests.cs
index a57a332bd..9a05caf2e 100644
--- a/tests/OpenCode.Sdk.Tests/Sessions/SessionInboxLiveTests.cs
+++ b/tests/OpenCode.Sdk.Tests/Sessions/SessionInboxLiveTests.cs
@@ -1,7 +1,7 @@
 using System.Globalization;
 using OpenCode.Sdk.Models;
 using OpenCode.Sdk.Tests.Harness;
-using OpenCode.Sdk.Tests.Support;
+using OpenCode.Sdk.Tests.Sessions.Support;
 
 namespace OpenCode.Sdk.Tests.Sessions;
 
diff --git a/tests/OpenCode.Sdk.Tests/Sessions/SessionLogCliProfileLiveTests.cs b/tests/OpenCode.Sdk.Tests/Sessions/SessionLogCliProfileLiveTests.cs
index 4632dae52..8bb97db5a 100644
--- a/tests/OpenCode.Sdk.Tests/Sessions/SessionLogCliProfileLiveTests.cs
+++ b/tests/OpenCode.Sdk.Tests/Sessions/SessionLogCliProfileLiveTests.cs
@@ -1,6 +1,7 @@
 using System.Globalization;
 using OpenCode.Sdk.Models;
 using OpenCode.Sdk.Tests.Harness;
+using OpenCode.Sdk.Tests.Sessions.Support;
 using OpenCode.Sdk.Tests.Support;
 
 namespace OpenCode.Sdk.Tests.Sessions;
diff --git a/tests/OpenCode.Sdk.Tests/Sessions/SessionLogLiveTests.cs b/tests/OpenCode.Sdk.Tests/Sessions/SessionLogLiveTests.cs
index 671f08667..3e658cc79 100644
--- a/tests/OpenCode.Sdk.Tests/Sessions/SessionLogLiveTests.cs
+++ b/tests/OpenCode.Sdk.Tests/Sessions/SessionLogLiveTests.cs
@@ -1,6 +1,7 @@
 using System.Globalization;
 using OpenCode.Sdk.Models;
 using OpenCode.Sdk.Tests.Harness;
+using OpenCode.Sdk.Tests.Sessions.Support;
 using OpenCode.Sdk.Tests.Support;
 
 namespace OpenCode.Sdk.Tests.Sessions;
diff --git a/tests/OpenCode.Sdk.Tests/Sessions/SessionMessagePaginationLiveTests.cs b/tests/OpenCode.Sdk.Tests/Sessions/SessionMessagePaginationLiveTests.cs
index 2caf756a5..248757c1d 100644
--- a/tests/OpenCode.Sdk.Tests/Sessions/SessionMessagePaginationLiveTests.cs
+++ b/tests/OpenCode.Sdk.Tests/Sessions/SessionMessagePaginationLiveTests.cs
@@ -2,6 +2,7 @@
 using System.Text.Json;
 using OpenCode.Sdk.Models;
 using OpenCode.Sdk.Tests.Harness;
+using OpenCode.Sdk.Tests.Sessions.Support;
 using OpenCode.Sdk.Tests.Support;
 using TUnit.Assertions.Enums;
 
diff --git a/tests/OpenCode.Sdk.Tests/Sessions/SessionMetadataLiveTests.cs b/tests/OpenCode.Sdk.Tests/Sessions/SessionMetadataLiveTests.cs
index 5b23dd417..3e506a31f 100644
--- a/tests/OpenCode.Sdk.Tests/Sessions/SessionMetadataLiveTests.cs
+++ b/tests/OpenCode.Sdk.Tests/Sessions/SessionMetadataLiveTests.cs
@@ -2,7 +2,7 @@
 using System.Text.Json;
 using OpenCode.Sdk.Models;
 using OpenCode.Sdk.Tests.Harness;
-using OpenCode.Sdk.Tests.Support;
+using OpenCode.Sdk.Tests.Sessions.Support;
 
 namespace OpenCode.Sdk.Tests.Sessions;
 
diff --git a/tests/OpenCode.Sdk.Tests/Sessions/SessionPermissionLiveTests.cs b/tests/OpenCode.Sdk.Tests/Sessions/SessionPermissionLiveTests.cs
index 13a68da60..f84edb4c4 100644
--- a/tests/OpenCode.Sdk.Tests/Sessions/SessionPermissionLiveTests.cs
+++ b/tests/OpenCode.Sdk.Tests/Sessions/SessionPermissionLiveTests.cs
@@ -1,5 +1,6 @@
 using OpenCode.Sdk.Models;
 using OpenCode.Sdk.Tests.Harness;
+using OpenCode.Sdk.Tests.Sessions.Support;
 using OpenCode.Sdk.Tests.Support;
 
 namespace OpenCode.Sdk.Tests.Sessions;
diff --git a/tests/OpenCode.Sdk.Tests/Sessions/SessionToolLifecycleLiveTests.cs b/tests/OpenCode.Sdk.Tests/Sessions/SessionToolLifecycleLiveTests.cs
index ecf1bbdc1..4ed661d37 100644
--- a/tests/OpenCode.Sdk.Tests/Sessions/SessionToolLifecycleLiveTests.cs
+++ b/tests/OpenCode.Sdk.Tests/Sessions/SessionToolLifecycleLiveTests.cs
@@ -1,6 +1,7 @@
 using System.Text.Json.Nodes;
 using OpenCode.Sdk.Models;
 using OpenCode.Sdk.Tests.Harness;
+using OpenCode.Sdk.Tests.Sessions.Support;
 using OpenCode.Sdk.Tests.Support;
 
 namespace OpenCode.Sdk.Tests.Sessions;
diff --git a/tests/OpenCode.Sdk.Tests/Sessions/SessionToolPermissionLiveTests.cs b/tests/OpenCode.Sdk.Tests/Sessions/SessionToolPermissionLiveTests.cs
index 2bbb0e31c..eb2d5dd91 100644
--- a/tests/OpenCode.Sdk.Tests/Sessions/SessionToolPermissionLiveTests.cs
+++ b/tests/OpenCode.Sdk.Tests/Sessions/SessionToolPermissionLiveTests.cs
@@ -2,6 +2,7 @@
 using System.Text.Json.Nodes;
 using OpenCode.Sdk.Models;
 using OpenCode.Sdk.Tests.Harness;
+using OpenCode.Sdk.Tests.Sessions.Support;
 using OpenCode.Sdk.Tests.Support;
 
 namespace OpenCode.Sdk.Tests.Sessions;
diff --git a/tests/OpenCode.Sdk.Tests/Sessions/SessionsClientLiveTests.cs b/tests/OpenCode.Sdk.Tests/Sessions/SessionsClientLiveTests.cs
index f283564fe..4be73d1bf 100644
--- a/tests/OpenCode.Sdk.Tests/Sessions/SessionsClientLiveTests.cs
+++ b/tests/OpenCode.Sdk.Tests/Sessions/SessionsClientLiveTests.cs
@@ -1,6 +1,7 @@
 using System.Globalization;
 using OpenCode.Sdk.Models;
 using OpenCode.Sdk.Tests.Harness;
+using OpenCode.Sdk.Tests.Sessions.Support;
 using OpenCode.Sdk.Tests.Support;
 using TUnit.Assertions.Enums;
 
diff --git a/tests/OpenCode.Sdk.Tests/Support/OwnedDriveInvocation.cs b/tests/OpenCode.Sdk.Tests/Sessions/Support/OwnedDriveInvocation.cs
similarity index 97%
rename from tests/OpenCode.Sdk.Tests/Support/OwnedDriveInvocation.cs
rename to tests/OpenCode.Sdk.Tests/Sessions/Support/OwnedDriveInvocation.cs
index 2cc1dfdc9..0c6d865b1 100644
--- a/tests/OpenCode.Sdk.Tests/Support/OwnedDriveInvocation.cs
+++ b/tests/OpenCode.Sdk.Tests/Sessions/Support/OwnedDriveInvocation.cs
@@ -1,6 +1,6 @@
 using OpenCode.Sdk.Tests.Harness;
 
-namespace OpenCode.Sdk.Tests.Support;
+namespace OpenCode.Sdk.Tests.Sessions.Support;
 
 internal sealed class OwnedDriveInvocation
 {
diff --git a/tests/OpenCode.Sdk.Tests/Support/OwnedSessionInboxCleanup.cs b/tests/OpenCode.Sdk.Tests/Sessions/Support/OwnedSessionInboxCleanup.cs
similarity index 99%
rename from tests/OpenCode.Sdk.Tests/Support/OwnedSessionInboxCleanup.cs
rename to tests/OpenCode.Sdk.Tests/Sessions/Support/OwnedSessionInboxCleanup.cs
index a3f18513e..79367d905 100644
--- a/tests/OpenCode.Sdk.Tests/Support/OwnedSessionInboxCleanup.cs
+++ b/tests/OpenCode.Sdk.Tests/Sessions/Support/OwnedSessionInboxCleanup.cs
@@ -5,7 +5,7 @@
 using OpenCode.Sdk.Tests.Harness.Ownership;
 using OpenCode.Sdk.Tests.Harness.Ownership.Abstractions;
 
-namespace OpenCode.Sdk.Tests.Support;
+namespace OpenCode.Sdk.Tests.Sessions.Support;
 
 internal sealed class OwnedSessionInboxCleanup
 {
diff --git a/tests/OpenCode.Sdk.Tests/Support/OwnedSessionInboxCleanupTests.cs b/tests/OpenCode.Sdk.Tests/Sessions/Support/OwnedSessionInboxCleanupTests.cs
similarity index 98%
rename from tests/OpenCode.Sdk.Tests/Support/OwnedSessionInboxCleanupTests.cs
rename to tests/OpenCode.Sdk.Tests/Sessions/Support/OwnedSessionInboxCleanupTests.cs
index 683402e96..bf9f1d61b 100644
--- a/tests/OpenCode.Sdk.Tests/Support/OwnedSessionInboxCleanupTests.cs
+++ b/tests/OpenCode.Sdk.Tests/Sessions/Support/OwnedSessionInboxCleanupTests.cs
@@ -1,7 +1,8 @@
 using OpenCode.Sdk.Tests.Harness;
 using OpenCode.Sdk.Tests.Harness.Ownership;
+using OpenCode.Sdk.Tests.Support;
 
-namespace OpenCode.Sdk.Tests.Support;
+namespace OpenCode.Sdk.Tests.Sessions.Support;
 
 public sealed class OwnedSessionInboxCleanupTests
 {
diff --git a/tests/OpenCode.Sdk.Tests/Support/OwnedToolScenario.cs b/tests/OpenCode.Sdk.Tests/Sessions/Support/OwnedToolScenario.cs
similarity index 99%
rename from tests/OpenCode.Sdk.Tests/Support/OwnedToolScenario.cs
rename to tests/OpenCode.Sdk.Tests/Sessions/Support/OwnedToolScenario.cs
index 34fb601b9..6c2e2e7df 100644
--- a/tests/OpenCode.Sdk.Tests/Support/OwnedToolScenario.cs
+++ b/tests/OpenCode.Sdk.Tests/Sessions/Support/OwnedToolScenario.cs
@@ -4,9 +4,9 @@
 using OpenCode.Sdk.Models;
 using OpenCode.Sdk.Tests.Harness;
 using OpenCode.Sdk.Tests.Harness.Ownership;
-using OpenCode.Sdk.Tests.Sessions.Support;
+using OpenCode.Sdk.Tests.Support;
 
-namespace OpenCode.Sdk.Tests.Support;
+namespace OpenCode.Sdk.Tests.Sessions.Support;
 
 /// <summary>
 /// One owned model-tool scenario over the shared simulated server: an isolated workspace, a
diff --git a/tests/OpenCode.Sdk.Tests/Support/PendingPermissionCleanup.cs b/tests/OpenCode.Sdk.Tests/Sessions/Support/PendingPermissionCleanup.cs
similarity index 95%
rename from tests/OpenCode.Sdk.Tests/Support/PendingPermissionCleanup.cs
rename to tests/OpenCode.Sdk.Tests/Sessions/Support/PendingPermissionCleanup.cs
index ea3c31a0a..a4644c194 100644
--- a/tests/OpenCode.Sdk.Tests/Support/PendingPermissionCleanup.cs
+++ b/tests/OpenCode.Sdk.Tests/Sessions/Support/PendingPermissionCleanup.cs
@@ -1,7 +1,7 @@
 using System.Globalization;
 using OpenCode.Sdk.Models;
 
-namespace OpenCode.Sdk.Tests.Support;
+namespace OpenCode.Sdk.Tests.Sessions.Support;
 
 internal sealed class PendingPermissionCleanup(SessionClient session)
 {
diff --git a/tests/OpenCode.Sdk.Tests/Support/PendingPermissionCleanupTests.cs b/tests/OpenCode.Sdk.Tests/Sessions/Support/PendingPermissionCleanupTests.cs
similarity index 98%
rename from tests/OpenCode.Sdk.Tests/Support/PendingPermissionCleanupTests.cs
rename to tests/OpenCode.Sdk.Tests/Sessions/Support/PendingPermissionCleanupTests.cs
index 7c0120451..cf4216c54 100644
--- a/tests/OpenCode.Sdk.Tests/Support/PendingPermissionCleanupTests.cs
+++ b/tests/OpenCode.Sdk.Tests/Sessions/Support/PendingPermissionCleanupTests.cs
@@ -1,7 +1,8 @@
 using OpenCode.Sdk.Models;
 using OpenCode.Sdk.Tests.Harness.Ownership;
+using OpenCode.Sdk.Tests.Support;
 
-namespace OpenCode.Sdk.Tests.Support;
+namespace OpenCode.Sdk.Tests.Sessions.Support;
 
 public sealed class PendingPermissionCleanupTests
 {
diff --git a/tests/OpenCode.Sdk.Tests/Support/SessionLogTranscript.cs b/tests/OpenCode.Sdk.Tests/Sessions/Support/SessionLogTranscript.cs
similarity index 98%
rename from tests/OpenCode.Sdk.Tests/Support/SessionLogTranscript.cs
rename to tests/OpenCode.Sdk.Tests/Sessions/Support/SessionLogTranscript.cs
index 7a4edea7f..a004019af 100644
--- a/tests/OpenCode.Sdk.Tests/Support/SessionLogTranscript.cs
+++ b/tests/OpenCode.Sdk.Tests/Sessions/Support/SessionLogTranscript.cs
@@ -1,6 +1,7 @@
 using OpenCode.Sdk.Models;
+using OpenCode.Sdk.Tests.Support;
 
-namespace OpenCode.Sdk.Tests.Support;
+namespace OpenCode.Sdk.Tests.Sessions.Support;
 
 internal sealed class SessionLogTranscript
 {
diff --git a/tests/OpenCode.Sdk.Tests/Support/SessionLogTranscriptTests.cs b/tests/OpenCode.Sdk.Tests/Sessions/Support/SessionLogTranscriptTests.cs
similarity index 98%
rename from tests/OpenCode.Sdk.Tests/Support/SessionLogTranscriptTests.cs
rename to tests/OpenCode.Sdk.Tests/Sessions/Support/SessionLogTranscriptTests.cs
index d6c1e153d..67f062772 100644
--- a/tests/OpenCode.Sdk.Tests/Support/SessionLogTranscriptTests.cs
+++ b/tests/OpenCode.Sdk.Tests/Sessions/Support/SessionLogTranscriptTests.cs
@@ -1,6 +1,7 @@
 using OpenCode.Sdk.Models;
+using OpenCode.Sdk.Tests.Support;
 
-namespace OpenCode.Sdk.Tests.Support;
+namespace OpenCode.Sdk.Tests.Sessions.Support;
 
 public sealed class SessionLogTranscriptTests
 {
diff --git a/tests/OpenCode.Sdk.Tests/Support/SessionMessageEvidence.cs b/tests/OpenCode.Sdk.Tests/Sessions/Support/SessionMessageEvidence.cs
similarity index 68%
rename from tests/OpenCode.Sdk.Tests/Support/SessionMessageEvidence.cs
rename to tests/OpenCode.Sdk.Tests/Sessions/Support/SessionMessageEvidence.cs
index 4d9e8002e..f215825bd 100644
--- a/tests/OpenCode.Sdk.Tests/Support/SessionMessageEvidence.cs
+++ b/tests/OpenCode.Sdk.Tests/Sessions/Support/SessionMessageEvidence.cs
@@ -1,3 +1,3 @@
-namespace OpenCode.Sdk.Tests.Support;
+namespace OpenCode.Sdk.Tests.Sessions.Support;
 
 internal sealed record SessionMessageEvidence(string Type, string Id, string Text, double Created);
diff --git a/tests/OpenCode.Sdk.Tests/Support/SessionMessageEvidenceProjector.cs b/tests/OpenCode.Sdk.Tests/Sessions/Support/SessionMessageEvidenceProjector.cs
similarity index 94%
rename from tests/OpenCode.Sdk.Tests/Support/SessionMessageEvidenceProjector.cs
rename to tests/OpenCode.Sdk.Tests/Sessions/Support/SessionMessageEvidenceProjector.cs
index 94b2fb902..7937c0c28 100644
--- a/tests/OpenCode.Sdk.Tests/Support/SessionMessageEvidenceProjector.cs
+++ b/tests/OpenCode.Sdk.Tests/Sessions/Support/SessionMessageEvidenceProjector.cs
@@ -1,7 +1,8 @@
 using System.Text.Json;
 using OpenCode.Sdk.Models;
+using OpenCode.Sdk.Tests.Support;
 
-namespace OpenCode.Sdk.Tests.Support;
+namespace OpenCode.Sdk.Tests.Sessions.Support;
 
 internal sealed class SessionMessageEvidenceProjector
 {
diff --git a/tests/OpenCode.Sdk.Tests/Support/SimulatedSessionTurn.cs b/tests/OpenCode.Sdk.Tests/Sessions/Support/SimulatedSessionTurn.cs
similarity index 98%
rename from tests/OpenCode.Sdk.Tests/Support/SimulatedSessionTurn.cs
rename to tests/OpenCode.Sdk.Tests/Sessions/Support/SimulatedSessionTurn.cs
index da8576f10..e8f5a691f 100644
--- a/tests/OpenCode.Sdk.Tests/Support/SimulatedSessionTurn.cs
+++ b/tests/OpenCode.Sdk.Tests/Sessions/Support/SimulatedSessionTurn.cs
@@ -1,7 +1,8 @@
 using OpenCode.Sdk.Models;
 using OpenCode.Sdk.Tests.Harness;
+using OpenCode.Sdk.Tests.Support;
 
-namespace OpenCode.Sdk.Tests.Support;
+namespace OpenCode.Sdk.Tests.Sessions.Support;
 
 /// <summary>
 /// One scripted turn against the simulated server: the subscription is attached before the prompt,
diff --git a/tests/OpenCode.Sdk.Tests/Support/LauncherHandleCensusTests.cs b/tests/OpenCode.Sdk.Tests/Shared/LauncherHandleCensusTests.cs
similarity index 98%
rename from tests/OpenCode.Sdk.Tests/Support/LauncherHandleCensusTests.cs
rename to tests/OpenCode.Sdk.Tests/Shared/LauncherHandleCensusTests.cs
index b6728cbec..2711ae520 100644
--- a/tests/OpenCode.Sdk.Tests/Support/LauncherHandleCensusTests.cs
+++ b/tests/OpenCode.Sdk.Tests/Shared/LauncherHandleCensusTests.cs
@@ -1,8 +1,9 @@
 using System.Globalization;
 using OpenCode.Sdk.Tests.Harness;
+using OpenCode.Sdk.Tests.Support;
 using Testably.Abstractions;
 
-namespace OpenCode.Sdk.Tests.Support;
+namespace OpenCode.Sdk.Tests.Shared;
 
 /// <summary>
 /// The census the Windows handle proof rests on: each launcher kind it counts shows while a handle
diff --git a/tests/OpenCode.Sdk.Tests/Fixtures/Skills/sdk-live-skill.md b/tests/OpenCode.Sdk.Tests/Skills/Fixtures/sdk-live-skill.md
similarity index 100%
rename from tests/OpenCode.Sdk.Tests/Fixtures/Skills/sdk-live-skill.md
rename to tests/OpenCode.Sdk.Tests/Skills/Fixtures/sdk-live-skill.md
diff --git a/tests/OpenCode.Sdk.Tests/TestMirrorTests.cs b/tests/OpenCode.Sdk.Tests/Support/TestMirrorTests.cs
similarity index 96%
rename from tests/OpenCode.Sdk.Tests/TestMirrorTests.cs
rename to tests/OpenCode.Sdk.Tests/Support/TestMirrorTests.cs
index 109ca7e54..dd6f0b2ad 100644
--- a/tests/OpenCode.Sdk.Tests/TestMirrorTests.cs
+++ b/tests/OpenCode.Sdk.Tests/Support/TestMirrorTests.cs
@@ -1,6 +1,4 @@
-using OpenCode.Sdk.Tests.Support;
-
-namespace OpenCode.Sdk.Tests;
+namespace OpenCode.Sdk.Tests.Support;
 
 /// <summary>
 /// The test mirror rule (<see cref="TestMirror"/>) against the real source tree, which must have no
diff --git a/tests/OpenCode.Sdk.Tests/Transport/CallerStreamContentTests.cs b/tests/OpenCode.Sdk.Tests/Transport/CallerStreamContentTests.cs
index 7edcade04..c56d5f938 100644
--- a/tests/OpenCode.Sdk.Tests/Transport/CallerStreamContentTests.cs
+++ b/tests/OpenCode.Sdk.Tests/Transport/CallerStreamContentTests.cs
@@ -1,5 +1,6 @@
 using OpenCode.Sdk.Internal;
 using OpenCode.Sdk.Tests.Support;
+using OpenCode.Sdk.Tests.Transport.Support;
 
 namespace OpenCode.Sdk.Tests.Transport;
 
diff --git a/tests/OpenCode.Sdk.Tests/Transport/NetworkTimeoutTests.cs b/tests/OpenCode.Sdk.Tests/Transport/NetworkTimeoutTests.cs
index 29bf226e1..728a87c41 100644
--- a/tests/OpenCode.Sdk.Tests/Transport/NetworkTimeoutTests.cs
+++ b/tests/OpenCode.Sdk.Tests/Transport/NetworkTimeoutTests.cs
@@ -1,6 +1,7 @@
 using System.Threading.Channels;
 using OpenCode.Sdk.Internal;
 using OpenCode.Sdk.Tests.Support;
+using OpenCode.Sdk.Tests.Transport.Support;
 
 namespace OpenCode.Sdk.Tests.Transport;
 
diff --git a/tests/OpenCode.Sdk.Tests/Transport/OwnedTransportTests.cs b/tests/OpenCode.Sdk.Tests/Transport/OwnedTransportTests.cs
index a31780837..919463d79 100644
--- a/tests/OpenCode.Sdk.Tests/Transport/OwnedTransportTests.cs
+++ b/tests/OpenCode.Sdk.Tests/Transport/OwnedTransportTests.cs
@@ -3,6 +3,7 @@
 using OpenCode.Sdk.Internal;
 using OpenCode.Sdk.Models;
 using OpenCode.Sdk.Tests.Support;
+using OpenCode.Sdk.Tests.Transport.Support;
 
 namespace OpenCode.Sdk.Tests.Transport;
 
diff --git a/tests/OpenCode.Sdk.Tests/Transport/PipelineMessageTests.cs b/tests/OpenCode.Sdk.Tests/Transport/PipelineMessageTests.cs
index 960e56130..0372d69cb 100644
--- a/tests/OpenCode.Sdk.Tests/Transport/PipelineMessageTests.cs
+++ b/tests/OpenCode.Sdk.Tests/Transport/PipelineMessageTests.cs
@@ -1,6 +1,6 @@
 using System.Net;
 using OpenCode.Sdk.Internal;
-using OpenCode.Sdk.Tests.Support;
+using OpenCode.Sdk.Tests.Transport.Support;
 
 namespace OpenCode.Sdk.Tests.Transport;
 
diff --git a/tests/OpenCode.Sdk.Tests/Transport/PipelineResponseOwnershipTests.cs b/tests/OpenCode.Sdk.Tests/Transport/PipelineResponseOwnershipTests.cs
index 9228312d5..cdb044a4e 100644
--- a/tests/OpenCode.Sdk.Tests/Transport/PipelineResponseOwnershipTests.cs
+++ b/tests/OpenCode.Sdk.Tests/Transport/PipelineResponseOwnershipTests.cs
@@ -1,6 +1,7 @@
 using System.Net;
 using OpenCode.Sdk.Internal;
 using OpenCode.Sdk.Tests.Support;
+using OpenCode.Sdk.Tests.Transport.Support;
 
 namespace OpenCode.Sdk.Tests.Transport;
 
diff --git a/tests/OpenCode.Sdk.Tests/Transport/PipelineStreamTests.cs b/tests/OpenCode.Sdk.Tests/Transport/PipelineStreamTests.cs
index aa3fe7c68..e589065c3 100644
--- a/tests/OpenCode.Sdk.Tests/Transport/PipelineStreamTests.cs
+++ b/tests/OpenCode.Sdk.Tests/Transport/PipelineStreamTests.cs
@@ -4,6 +4,7 @@
 using OpenCode.Sdk.Internal;
 using OpenCode.Sdk.Models;
 using OpenCode.Sdk.Tests.Support;
+using OpenCode.Sdk.Tests.Transport.Support;
 
 namespace OpenCode.Sdk.Tests.Transport;
 
diff --git a/tests/OpenCode.Sdk.Tests/Transport/PipelineTests.cs b/tests/OpenCode.Sdk.Tests/Transport/PipelineTests.cs
index 0d46285da..55c3a51d7 100644
--- a/tests/OpenCode.Sdk.Tests/Transport/PipelineTests.cs
+++ b/tests/OpenCode.Sdk.Tests/Transport/PipelineTests.cs
@@ -5,6 +5,7 @@
 using OpenCode.Sdk.Internal;
 using OpenCode.Sdk.Models;
 using OpenCode.Sdk.Tests.Support;
+using OpenCode.Sdk.Tests.Transport.Support;
 
 namespace OpenCode.Sdk.Tests.Transport;
 
diff --git a/tests/OpenCode.Sdk.Tests/Transport/RequestDecorationPolicyTests.cs b/tests/OpenCode.Sdk.Tests/Transport/RequestDecorationPolicyTests.cs
index e019d4f6a..eea73a0be 100644
--- a/tests/OpenCode.Sdk.Tests/Transport/RequestDecorationPolicyTests.cs
+++ b/tests/OpenCode.Sdk.Tests/Transport/RequestDecorationPolicyTests.cs
@@ -1,5 +1,6 @@
 using OpenCode.Sdk.Internal;
 using OpenCode.Sdk.Tests.Support;
+using OpenCode.Sdk.Tests.Transport.Support;
 
 namespace OpenCode.Sdk.Tests.Transport;
 
diff --git a/tests/OpenCode.Sdk.Tests/Transport/ResponseBufferingPolicyTests.cs b/tests/OpenCode.Sdk.Tests/Transport/ResponseBufferingPolicyTests.cs
index b9f8f9a38..563753a67 100644
--- a/tests/OpenCode.Sdk.Tests/Transport/ResponseBufferingPolicyTests.cs
+++ b/tests/OpenCode.Sdk.Tests/Transport/ResponseBufferingPolicyTests.cs
@@ -3,6 +3,7 @@
 using System.Text;
 using OpenCode.Sdk.Internal;
 using OpenCode.Sdk.Tests.Support;
+using OpenCode.Sdk.Tests.Transport.Support;
 #if !NET
 using TUnit.Assertions.Enums;
 #endif
diff --git a/tests/OpenCode.Sdk.Tests/Support/CancelingContent.cs b/tests/OpenCode.Sdk.Tests/Transport/Support/CancelingContent.cs
similarity index 95%
rename from tests/OpenCode.Sdk.Tests/Support/CancelingContent.cs
rename to tests/OpenCode.Sdk.Tests/Transport/Support/CancelingContent.cs
index ff4849722..a8070b7bb 100644
--- a/tests/OpenCode.Sdk.Tests/Support/CancelingContent.cs
+++ b/tests/OpenCode.Sdk.Tests/Transport/Support/CancelingContent.cs
@@ -1,7 +1,7 @@
 using System.Net;
 using OpenCode.Sdk.Internal;
 
-namespace OpenCode.Sdk.Tests.Support;
+namespace OpenCode.Sdk.Tests.Transport.Support;
 
 /// <summary>Cancels the caller token while a one-shot response body is being buffered.</summary>
 internal sealed class CancelingContent : HttpContent
diff --git a/tests/OpenCode.Sdk.Tests/Support/CancelingStream.cs b/tests/OpenCode.Sdk.Tests/Transport/Support/CancelingStream.cs
similarity index 96%
rename from tests/OpenCode.Sdk.Tests/Support/CancelingStream.cs
rename to tests/OpenCode.Sdk.Tests/Transport/Support/CancelingStream.cs
index eeb9b7b3c..78869afe3 100644
--- a/tests/OpenCode.Sdk.Tests/Support/CancelingStream.cs
+++ b/tests/OpenCode.Sdk.Tests/Transport/Support/CancelingStream.cs
@@ -1,4 +1,4 @@
-namespace OpenCode.Sdk.Tests.Support;
+namespace OpenCode.Sdk.Tests.Transport.Support;
 
 /// <summary>Fails reads as transport-originated cancellation without canceling the caller token.</summary>
 internal sealed class CancelingStream : Stream
diff --git a/tests/OpenCode.Sdk.Tests/Support/DisposalTrackingContent.cs b/tests/OpenCode.Sdk.Tests/Transport/Support/DisposalTrackingContent.cs
similarity index 89%
rename from tests/OpenCode.Sdk.Tests/Support/DisposalTrackingContent.cs
rename to tests/OpenCode.Sdk.Tests/Transport/Support/DisposalTrackingContent.cs
index 307b5a9a1..202ce3928 100644
--- a/tests/OpenCode.Sdk.Tests/Support/DisposalTrackingContent.cs
+++ b/tests/OpenCode.Sdk.Tests/Transport/Support/DisposalTrackingContent.cs
@@ -1,4 +1,4 @@
-namespace OpenCode.Sdk.Tests.Support;
+namespace OpenCode.Sdk.Tests.Transport.Support;
 
 /// <summary>Tracks whether the response owner disposed a buffered string body.</summary>
 internal sealed class DisposalTrackingContent : StringContent
diff --git a/tests/OpenCode.Sdk.Tests/Support/DisposalTrackingResponse.cs b/tests/OpenCode.Sdk.Tests/Transport/Support/DisposalTrackingResponse.cs
similarity index 92%
rename from tests/OpenCode.Sdk.Tests/Support/DisposalTrackingResponse.cs
rename to tests/OpenCode.Sdk.Tests/Transport/Support/DisposalTrackingResponse.cs
index f951e0c5a..14216a3de 100644
--- a/tests/OpenCode.Sdk.Tests/Support/DisposalTrackingResponse.cs
+++ b/tests/OpenCode.Sdk.Tests/Transport/Support/DisposalTrackingResponse.cs
@@ -1,6 +1,6 @@
 using System.Net;
 
-namespace OpenCode.Sdk.Tests.Support;
+namespace OpenCode.Sdk.Tests.Transport.Support;
 
 /// <summary>Tracks whether the pipeline released the response as well as its content.</summary>
 internal sealed class DisposalTrackingResponse : HttpResponseMessage
diff --git a/tests/OpenCode.Sdk.Tests/Support/FaultingStream.cs b/tests/OpenCode.Sdk.Tests/Transport/Support/FaultingStream.cs
similarity index 97%
rename from tests/OpenCode.Sdk.Tests/Support/FaultingStream.cs
rename to tests/OpenCode.Sdk.Tests/Transport/Support/FaultingStream.cs
index 0455f7f1c..0cbdecac3 100644
--- a/tests/OpenCode.Sdk.Tests/Support/FaultingStream.cs
+++ b/tests/OpenCode.Sdk.Tests/Transport/Support/FaultingStream.cs
@@ -1,4 +1,4 @@
-namespace OpenCode.Sdk.Tests.Support;
+namespace OpenCode.Sdk.Tests.Transport.Support;
 
 /// <summary>
 /// Serves one prepared prefix and then fails the way a connection dropped mid-body does,
diff --git a/tests/OpenCode.Sdk.Tests/Support/InterruptedBufferingContent.cs b/tests/OpenCode.Sdk.Tests/Transport/Support/InterruptedBufferingContent.cs
similarity index 96%
rename from tests/OpenCode.Sdk.Tests/Support/InterruptedBufferingContent.cs
rename to tests/OpenCode.Sdk.Tests/Transport/Support/InterruptedBufferingContent.cs
index 88402c68b..74723d568 100644
--- a/tests/OpenCode.Sdk.Tests/Support/InterruptedBufferingContent.cs
+++ b/tests/OpenCode.Sdk.Tests/Transport/Support/InterruptedBufferingContent.cs
@@ -1,6 +1,7 @@
 using System.Net;
+using OpenCode.Sdk.Tests.Support;
 
-namespace OpenCode.Sdk.Tests.Support;
+namespace OpenCode.Sdk.Tests.Transport.Support;
 
 /// <summary>
 /// Reproduces .NET 10's <c>HttpContent</c> failure mode deterministically: the read-stream
diff --git a/tests/OpenCode.Sdk.Tests/Support/ReadObservingContent.cs b/tests/OpenCode.Sdk.Tests/Transport/Support/ReadObservingContent.cs
similarity index 96%
rename from tests/OpenCode.Sdk.Tests/Support/ReadObservingContent.cs
rename to tests/OpenCode.Sdk.Tests/Transport/Support/ReadObservingContent.cs
index 27eb97669..32cda0643 100644
--- a/tests/OpenCode.Sdk.Tests/Support/ReadObservingContent.cs
+++ b/tests/OpenCode.Sdk.Tests/Transport/Support/ReadObservingContent.cs
@@ -1,6 +1,6 @@
 using System.Net;
 
-namespace OpenCode.Sdk.Tests.Support;
+namespace OpenCode.Sdk.Tests.Transport.Support;
 
 /// <summary>A body that completes immediately and records whether the pipeline drained it.</summary>
 internal sealed class ReadObservingContent : HttpContent
diff --git a/tests/OpenCode.Sdk.Tests/Support/RecordingResponseAdapter.cs b/tests/OpenCode.Sdk.Tests/Transport/Support/RecordingResponseAdapter.cs
similarity index 93%
rename from tests/OpenCode.Sdk.Tests/Support/RecordingResponseAdapter.cs
rename to tests/OpenCode.Sdk.Tests/Transport/Support/RecordingResponseAdapter.cs
index 60163366c..83b21507d 100644
--- a/tests/OpenCode.Sdk.Tests/Support/RecordingResponseAdapter.cs
+++ b/tests/OpenCode.Sdk.Tests/Transport/Support/RecordingResponseAdapter.cs
@@ -1,7 +1,8 @@
 using System.Text;
 using OpenCode.Sdk.Internal;
+using OpenCode.Sdk.Tests.Support;
 
-namespace OpenCode.Sdk.Tests.Support;
+namespace OpenCode.Sdk.Tests.Transport.Support;
 
 internal sealed class RecordingResponseAdapter : ResponseAdapter<TestResponse>
 {
diff --git a/tests/OpenCode.Sdk.Tests/Support/ScriptedFramer.cs b/tests/OpenCode.Sdk.Tests/Transport/Support/ScriptedFramer.cs
similarity index 95%
rename from tests/OpenCode.Sdk.Tests/Support/ScriptedFramer.cs
rename to tests/OpenCode.Sdk.Tests/Transport/Support/ScriptedFramer.cs
index 09d404a60..dcbc1527e 100644
--- a/tests/OpenCode.Sdk.Tests/Support/ScriptedFramer.cs
+++ b/tests/OpenCode.Sdk.Tests/Transport/Support/ScriptedFramer.cs
@@ -1,7 +1,7 @@
 using System.Runtime.CompilerServices;
 using OpenCode.Sdk.Internal;
 
-namespace OpenCode.Sdk.Tests.Support;
+namespace OpenCode.Sdk.Tests.Transport.Support;
 
 /// <summary>Substitutes the framer seam: yields a scripted frame sequence and records what it framed.</summary>
 internal sealed class ScriptedFramer : IEventStreamFramer
diff --git a/tests/OpenCode.Sdk.Tests/Support/TimeoutContent.cs b/tests/OpenCode.Sdk.Tests/Transport/Support/TimeoutContent.cs
similarity index 89%
rename from tests/OpenCode.Sdk.Tests/Support/TimeoutContent.cs
rename to tests/OpenCode.Sdk.Tests/Transport/Support/TimeoutContent.cs
index d153be81f..36837a866 100644
--- a/tests/OpenCode.Sdk.Tests/Support/TimeoutContent.cs
+++ b/tests/OpenCode.Sdk.Tests/Transport/Support/TimeoutContent.cs
@@ -1,6 +1,6 @@
 using System.Net;
 
-namespace OpenCode.Sdk.Tests.Support;
+namespace OpenCode.Sdk.Tests.Transport.Support;
 
 /// <summary>Simulates the transport timing out while the response body streams.</summary>
 internal sealed class TimeoutContent : HttpContent
diff --git a/tests/OpenCode.Sdk.Tests/Support/TrackingByteArrayPool.cs b/tests/OpenCode.Sdk.Tests/Transport/Support/TrackingByteArrayPool.cs
similarity index 97%
rename from tests/OpenCode.Sdk.Tests/Support/TrackingByteArrayPool.cs
rename to tests/OpenCode.Sdk.Tests/Transport/Support/TrackingByteArrayPool.cs
index 6b1a3c4fd..2a9ca3ddf 100644
--- a/tests/OpenCode.Sdk.Tests/Support/TrackingByteArrayPool.cs
+++ b/tests/OpenCode.Sdk.Tests/Transport/Support/TrackingByteArrayPool.cs
@@ -1,6 +1,6 @@
 using System.Buffers;
 
-namespace OpenCode.Sdk.Tests.Support;
+namespace OpenCode.Sdk.Tests.Transport.Support;
 
 /// <summary>Tracks byte-array ownership and pre-fills spare capacity so tests catch out-of-range reads.</summary>
 internal sealed class TrackingByteArrayPool : ArrayPool<byte>
diff --git a/tests/OpenCode.Sdk.Tests/Fixtures/Serialization/known-websearch-response.json b/tests/OpenCode.Sdk.Tests/Websearch/Fixtures/known-websearch-response.json
similarity index 100%
rename from tests/OpenCode.Sdk.Tests/Fixtures/Serialization/known-websearch-response.json
rename to tests/OpenCode.Sdk.Tests/Websearch/Fixtures/known-websearch-response.json
diff --git a/tests/OpenCode.Sdk.Tests/Support/OwnedWorktreeScenario.cs b/tests/OpenCode.Sdk.Tests/Worktrees/Support/OwnedWorktreeScenario.cs
similarity index 98%
rename from tests/OpenCode.Sdk.Tests/Support/OwnedWorktreeScenario.cs
rename to tests/OpenCode.Sdk.Tests/Worktrees/Support/OwnedWorktreeScenario.cs
index 31a7f1c5e..ae8f40bf3 100644
--- a/tests/OpenCode.Sdk.Tests/Support/OwnedWorktreeScenario.cs
+++ b/tests/OpenCode.Sdk.Tests/Worktrees/Support/OwnedWorktreeScenario.cs
@@ -3,7 +3,7 @@
 using OpenCode.Sdk.Tests.Harness;
 using OpenCode.Sdk.Tests.Harness.Ownership;
 
-namespace OpenCode.Sdk.Tests.Support;
+namespace OpenCode.Sdk.Tests.Worktrees.Support;
 
 /// <summary>
 /// Owns a live worktree scenario's Git repository workspace from creation to teardown: the
diff --git a/tests/OpenCode.Sdk.Tests/Worktrees/WorktreesClientLiveTests.cs b/tests/OpenCode.Sdk.Tests/Worktrees/WorktreesClientLiveTests.cs
index 229556c58..321861441 100644
--- a/tests/OpenCode.Sdk.Tests/Worktrees/WorktreesClientLiveTests.cs
+++ b/tests/OpenCode.Sdk.Tests/Worktrees/WorktreesClientLiveTests.cs
@@ -1,7 +1,7 @@
 using System.Globalization;
 using OpenCode.Sdk.Models;
 using OpenCode.Sdk.Tests.Harness;
-using OpenCode.Sdk.Tests.Support;
+using OpenCode.Sdk.Tests.Worktrees.Support;
 
 namespace OpenCode.Sdk.Tests.Worktrees;
 
diff --git a/tests/OpenCode.Sdk.Tools.Tests/RepositoryGates/collapsed-assertions.txt b/tests/OpenCode.Sdk.Tools.Tests/RepositoryGates/collapsed-assertions.txt
index c522dc93f..60bfd20cd 100644
--- a/tests/OpenCode.Sdk.Tools.Tests/RepositoryGates/collapsed-assertions.txt
+++ b/tests/OpenCode.Sdk.Tools.Tests/RepositoryGates/collapsed-assertions.txt
@@ -32,9 +32,9 @@ tests/OpenCode.Sdk.Tests/PersistentPtys/PersistentPtySessionTests.cs	1
 tests/OpenCode.Sdk.Tests/PersistentPtys/PersistentPtyUpgradeFailurePolicyTests.cs	1
 tests/OpenCode.Sdk.Tests/Ptys/PtySessionTests.cs	2
 tests/OpenCode.Sdk.Tests/Ptys/PtysClientContractTests.cs	3
-tests/OpenCode.Sdk.Tests/SecretMemberPrintingTests.cs	1
 tests/OpenCode.Sdk.Tests/Serialization/OpenCodeJsonContextTests.cs	4
 tests/OpenCode.Sdk.Tests/Serialization/OpenModelRoundTripTests.cs	1
+tests/OpenCode.Sdk.Tests/Serialization/SecretMemberPrintingTests.cs	1
 tests/OpenCode.Sdk.Tests/Server/ServerClientLiveTests.cs	1
 tests/OpenCode.Sdk.Tests/Sessions/SessionClientContractTests.cs	1
 tests/OpenCode.Sdk.Tests/Sessions/SessionClientPaginationTests.cs	4
@@ -46,9 +46,9 @@ tests/OpenCode.Sdk.Tests/Sessions/SessionParentFilterTests.cs	1
 tests/OpenCode.Sdk.Tests/Sessions/SessionPermissionLiveTests.cs	2
 tests/OpenCode.Sdk.Tests/Sessions/SessionsClientContractTests.cs	2
 tests/OpenCode.Sdk.Tests/Sessions/SessionsClientLiveTests.cs	11
+tests/OpenCode.Sdk.Tests/Sessions/Support/SessionLogTranscriptTests.cs	1
 tests/OpenCode.Sdk.Tests/Streaming/ServerSentEventReaderTests.cs	7
 tests/OpenCode.Sdk.Tests/Support/OwnedEventReaderTests.cs	1
-tests/OpenCode.Sdk.Tests/Support/SessionLogTranscriptTests.cs	1
 tests/OpenCode.Sdk.Tests/Transport/PipelineStreamTests.cs	2
 tests/OpenCode.Sdk.Tests/Transport/PipelineTests.cs	7
 tests/OpenCode.Sdk.Tests/Transport/RequestDecorationPolicyTests.cs	7
diff --git a/tests/OpenCode.Sdk.Tools.Tests/RepositoryGates/order-blind-equivalence.txt b/tests/OpenCode.Sdk.Tools.Tests/RepositoryGates/order-blind-equivalence.txt
index 0f9d4c15c..e474ccb75 100644
--- a/tests/OpenCode.Sdk.Tools.Tests/RepositoryGates/order-blind-equivalence.txt
+++ b/tests/OpenCode.Sdk.Tools.Tests/RepositoryGates/order-blind-equivalence.txt
@@ -27,9 +27,9 @@ tests/OpenCode.Sdk.Tests/Sessions/GettingStartedRecipeLiveTests.cs	1
 tests/OpenCode.Sdk.Tests/Sessions/SessionInboxLiveTests.cs	2
 tests/OpenCode.Sdk.Tests/Sessions/SessionMetadataLiveTests.cs	2
 tests/OpenCode.Sdk.Tests/Sessions/SessionPermissionLiveTests.cs	2
+tests/OpenCode.Sdk.Tests/Sessions/Support/PendingPermissionCleanupTests.cs	1
 tests/OpenCode.Sdk.Tests/Support/OwnedEventReaderTests.cs	3
-tests/OpenCode.Sdk.Tests/Support/PendingPermissionCleanupTests.cs	1
-tests/OpenCode.Sdk.Tests/TestMirrorTests.cs	1
+tests/OpenCode.Sdk.Tests/Support/TestMirrorTests.cs	1
 tests/OpenCode.Sdk.Tests/Transport/CallerStreamContentTests.cs	3
 tests/OpenCode.Sdk.Tests/Transport/NetworkTimeoutTests.cs	1
 tests/OpenCode.Sdk.Tests/Transport/OwnedTransportTests.cs	1
diff --git a/tests/OpenCode.Sdk.Tools.Tests/RepositoryGates/real-clock.txt b/tests/OpenCode.Sdk.Tools.Tests/RepositoryGates/real-clock.txt
index c42935e3e..98830c061 100644
--- a/tests/OpenCode.Sdk.Tools.Tests/RepositoryGates/real-clock.txt
+++ b/tests/OpenCode.Sdk.Tools.Tests/RepositoryGates/real-clock.txt
@@ -22,23 +22,23 @@ tests/OpenCode.Sdk.Tests/Hosting/Launcher/OpenCodeServerJobTests.cs	4
 tests/OpenCode.Sdk.Tests/Hosting/Launcher/OpenCodeServerLifecycleTests.cs	3
 tests/OpenCode.Sdk.Tests/Hosting/Launcher/OpenCodeServerProcessGroupTests.cs	5
 tests/OpenCode.Sdk.Tests/Hosting/Launcher/PosixServerLadderTests.cs	4
+tests/OpenCode.Sdk.Tests/Hosting/Launcher/Support/LadderTree.cs	2
+tests/OpenCode.Sdk.Tests/Hosting/Launcher/Support/RecordingTreeKill.cs	2
+tests/OpenCode.Sdk.Tests/Hosting/Launcher/Support/ServerStartupTreeHandshake.cs	1
+tests/OpenCode.Sdk.Tests/Hosting/Launcher/Support/ServerStartupTreeScenario.cs	3
 tests/OpenCode.Sdk.Tests/Hosting/Platform/Windows/TaskkillTreeKillTests.cs	1
 tests/OpenCode.Sdk.Tests/Hosting/Platform/Windows/WindowsExitWatchTests.cs	2
 tests/OpenCode.Sdk.Tests/LocationTargetingLiveTests.cs	1
 tests/OpenCode.Sdk.Tests/PersistentPtys/PersistentPtySessionTests.cs	1
 tests/OpenCode.Sdk.Tests/Ptys/PtySessionTests.cs	1
+tests/OpenCode.Sdk.Tests/Ptys/Support/PtyFailureDiagnosticsTests.cs	1
+tests/OpenCode.Sdk.Tests/Ptys/Support/PtyLiveTranscript.cs	2
 tests/OpenCode.Sdk.Tests/Sessions/SessionLogCliProfileLiveTests.cs	2
 tests/OpenCode.Sdk.Tests/Sessions/SessionMetadataLiveTests.cs	1
 tests/OpenCode.Sdk.Tests/Sessions/SessionPermissionRulesLiveTests.cs	1
-tests/OpenCode.Sdk.Tests/Support/LadderTree.cs	2
+tests/OpenCode.Sdk.Tests/Sessions/Support/SessionLogTranscript.cs	1
 tests/OpenCode.Sdk.Tests/Support/LiveReadiness.cs	3
 tests/OpenCode.Sdk.Tests/Support/OwnedEventReader.cs	1
 tests/OpenCode.Sdk.Tests/Support/ProcessObservation.cs	1
-tests/OpenCode.Sdk.Tests/Support/PtyFailureDiagnosticsTests.cs	1
-tests/OpenCode.Sdk.Tests/Support/PtyLiveTranscript.cs	2
-tests/OpenCode.Sdk.Tests/Support/RecordingTreeKill.cs	2
 tests/OpenCode.Sdk.Tests/Support/ServerDiagnosticScenario.cs	1
-tests/OpenCode.Sdk.Tests/Support/ServerStartupTreeHandshake.cs	1
-tests/OpenCode.Sdk.Tests/Support/ServerStartupTreeScenario.cs	3
 tests/OpenCode.Sdk.Tests/Support/SessionEventProbe.cs	1
-tests/OpenCode.Sdk.Tests/Support/SessionLogTranscript.cs	1
diff --git a/tests/OpenCode.Sdk.Tools.Tests/Snapshots/SuppressionLedgerTests.Ledger_Should_Count_Every_Suppression_In_The_Repository.verified.txt b/tests/OpenCode.Sdk.Tools.Tests/Snapshots/SuppressionLedgerTests.Ledger_Should_Count_Every_Suppression_In_The_Repository.verified.txt
index ca60a74ff..c0b4f0912 100644
--- a/tests/OpenCode.Sdk.Tools.Tests/Snapshots/SuppressionLedgerTests.Ledger_Should_Count_Every_Suppression_In_The_Repository.verified.txt
+++ b/tests/OpenCode.Sdk.Tools.Tests/Snapshots/SuppressionLedgerTests.Ledger_Should_Count_Every_Suppression_In_The_Repository.verified.txt
@@ -151,10 +151,13 @@ editorconfig .editorconfig [tests/OpenCode.Sdk.Tests/Hosting/BackgroundService/S
 editorconfig .editorconfig [tests/OpenCode.Sdk.Tests/Hosting/BackgroundService/ServiceFileSystemTests.cs] dotnet_diagnostic.VSTHRD103.severity = none
 editorconfig .editorconfig [tests/OpenCode.Sdk.Tests/Hosting/BackgroundService/Stop/OpenCodeServerStop{Live,Escalation}Tests.cs] dotnet_diagnostic.MA0045.severity = none
 editorconfig .editorconfig [tests/OpenCode.Sdk.Tests/Hosting/BackgroundService/Stop/ServiceStopperTests.cs] dotnet_diagnostic.MA0045.severity = none
+editorconfig .editorconfig [tests/OpenCode.Sdk.Tests/Hosting/Launcher/Support/PathCommandShim.cs] dotnet_diagnostic.MA0045.severity = none
 editorconfig .editorconfig [tests/OpenCode.Sdk.Tests/Hosting/OpenCodeServerContractTests.cs] dotnet_diagnostic.CA2000.severity = none
 editorconfig .editorconfig [tests/OpenCode.Sdk.Tests/PersistentPtys/PersistentPtySessionTests.cs] dotnet_diagnostic.CA2000.severity = none
 editorconfig .editorconfig [tests/OpenCode.Sdk.Tests/Ptys/PtySessionTests.cs] dotnet_diagnostic.CA2000.severity = none
+editorconfig .editorconfig [tests/OpenCode.Sdk.Tests/Ptys/Support/PtyFailureDiagnosticsTests.cs] dotnet_diagnostic.VSTHRD003.severity = none
 editorconfig .editorconfig [tests/OpenCode.Sdk.Tests/Sessions/SessionMessagePaginationLiveTests.cs] dotnet_diagnostic.VSTHRD003.severity = none
+editorconfig .editorconfig [tests/OpenCode.Sdk.Tests/Sessions/Support/SessionLogTranscriptTests.cs] dotnet_diagnostic.VSTHRD003.severity = none
 editorconfig .editorconfig [tests/OpenCode.Sdk.Tests/Support/BlockingStream.cs] dotnet_diagnostic.CA1844.severity = none
 editorconfig .editorconfig [tests/OpenCode.Sdk.Tests/Support/ChildExitObservation.cs] dotnet_diagnostic.VSTHRD003.severity = none
 editorconfig .editorconfig [tests/OpenCode.Sdk.Tests/Support/ControlledOperationDeadline.cs] dotnet_diagnostic.VSTHRD003.severity = none
@@ -162,13 +165,10 @@ editorconfig .editorconfig [tests/OpenCode.Sdk.Tests/Support/OperationDeadlineSc
 editorconfig .editorconfig [tests/OpenCode.Sdk.Tests/Support/OwnedCleanupDeadlineTests.cs] dotnet_diagnostic.VSTHRD003.severity = none
 editorconfig .editorconfig [tests/OpenCode.Sdk.Tests/Support/OwnedEventReader.cs] dotnet_diagnostic.VSTHRD003.severity = none
 editorconfig .editorconfig [tests/OpenCode.Sdk.Tests/Support/OwnedEventReaderTests.cs] dotnet_diagnostic.VSTHRD003.severity = none
-editorconfig .editorconfig [tests/OpenCode.Sdk.Tests/Support/PathCommandShim.cs] dotnet_diagnostic.MA0045.severity = none
-editorconfig .editorconfig [tests/OpenCode.Sdk.Tests/Support/PtyFailureDiagnosticsTests.cs] dotnet_diagnostic.VSTHRD003.severity = none
 editorconfig .editorconfig [tests/OpenCode.Sdk.Tests/Support/ScriptedTerminalWebSocket.cs] dotnet_diagnostic.VSTHRD003.severity = none
 editorconfig .editorconfig [tests/OpenCode.Sdk.Tests/Support/ServerDiagnosticScenario.cs] dotnet_diagnostic.VSTHRD003.severity = none
 editorconfig .editorconfig [tests/OpenCode.Sdk.Tests/Support/SessionEventProbe.cs] dotnet_diagnostic.VSTHRD003.severity = none
 editorconfig .editorconfig [tests/OpenCode.Sdk.Tests/Support/SessionEventProbeTests.cs] dotnet_diagnostic.VSTHRD003.severity = none
-editorconfig .editorconfig [tests/OpenCode.Sdk.Tests/Support/SessionLogTranscriptTests.cs] dotnet_diagnostic.VSTHRD003.severity = none
 editorconfig .editorconfig [tests/Shared/ProcessMark.cs] dotnet_diagnostic.MA0045.severity = none
 editorconfig .editorconfig [tools/OpenCode.Sdk.Tools/Generator/Ingestion/Projection/EnumSchemaProjector.cs] dotnet_diagnostic.CA1822.severity = none
 editorconfig .editorconfig [tools/OpenCode.Sdk.Tools/Generator/Ingestion/Projection/EnumSchemaProjector.cs] dotnet_diagnostic.S2325.severity = none
@@ -210,12 +210,12 @@ pragma src/OpenCode.Sdk/Internal/Terminal/TerminalReceivePump.cs VSTHRD003
 pragma tests/OpenCode.Sdk.Tests/Hosting/BackgroundService/Ensure/ServiceEnsurerTests.cs MA0045
 pragma tests/OpenCode.Sdk.Tests/Hosting/BackgroundService/Handoff/ServicePtyHandoffScenario.cs MA0045
 pragma tests/OpenCode.Sdk.Tests/Hosting/BackgroundService/Handoff/ServicePtyHandoffTests.cs MA0045
+pragma tests/OpenCode.Sdk.Tests/Hosting/Launcher/Support/LauncherHost.cs VSTHRD003
 pragma tests/OpenCode.Sdk.Tests/PersistentPtys/PersistentPtySessionTests.cs CA2025
+pragma tests/OpenCode.Sdk.Tests/Ptys/Support/PtyDiagnosticServer.cs VSTHRD003
 pragma tests/OpenCode.Sdk.Tests/Support/DiagnosticWriteBarrier.cs VSTHRD003
 pragma tests/OpenCode.Sdk.Tests/Support/Gate.cs VSTHRD003
-pragma tests/OpenCode.Sdk.Tests/Support/LauncherHost.cs VSTHRD003
 pragma tests/OpenCode.Sdk.Tests/Support/LoopbackHttpServer.cs VSTHRD003
-pragma tests/OpenCode.Sdk.Tests/Support/PtyDiagnosticServer.cs VSTHRD003
 pragma tests/OpenCode.Sdk.Tests/Transport/OwnedTransportTests.cs VSTHRD003
 pragma tools/OpenCode.Sdk.Tools/Generator/Emission/ExperimentalAttributeSyntax.cs S1075
 pragma tools/OpenCode.Sdk.Tools/Generator/Ingestion/Projection/AllOfWrapperKeywords.cs CS0618
@@ -246,8 +246,8 @@ slopwatch-suppress tests/OpenCode.Sdk.ServiceFixture/WindowsLauncherProbe.cs SW0
 slopwatch-suppress tests/OpenCode.Sdk.Tests/Harness/MachineLock.cs SW004
 slopwatch-suppress tests/OpenCode.Sdk.Tests/Harness/PinnedManagedServiceFixture.cs SW004
 slopwatch-suppress tests/OpenCode.Sdk.Tests/Hosting/Launcher/OpenCodeServerJobTests.cs SW004
+slopwatch-suppress tests/OpenCode.Sdk.Tests/Hosting/Launcher/Support/LadderTree.cs SW004
 slopwatch-suppress tests/OpenCode.Sdk.Tests/Hosting/Platform/Windows/WindowsExitWatchTests.cs SW004
-slopwatch-suppress tests/OpenCode.Sdk.Tests/Support/LadderTree.cs SW004
 slopwatch-suppress tests/OpenCode.Sdk.Tests/Support/LiveReadiness.cs SW004
 slopwatch-suppress tests/OpenCode.Sdk.Tests/Support/ProcessObservation.cs SW003
 slopwatch-suppress tests/OpenCode.Sdk.Tools.Tests/Packaging/PackedConsumerFeed.cs SW003
diff --git a/tools/jscpd/src.baseline.json b/tools/jscpd/src.baseline.json
index 7db9b06dc..a2bc50a59 100644
--- a/tools/jscpd/src.baseline.json
+++ b/tools/jscpd/src.baseline.json
@@ -3,7 +3,6 @@
   "fingerprints": {
     "173100cf60860d5c": 1,
     "379f83d9f5f49b50": 1,
-    "694a350883370d46": 1,
     "7efebb0c6647bc37": 1
   }
 }
diff --git a/tools/jscpd/tests.baseline.json b/tools/jscpd/tests.baseline.json
index 0b762c77d..3d78de49d 100644
--- a/tools/jscpd/tests.baseline.json
+++ b/tools/jscpd/tests.baseline.json
@@ -46,10 +46,11 @@
     "0a6e5c2d3b8c81ff": 1,
     "0a83952fafd4de0d": 1,
     "0aa5ac7a294d6eeb": 1,
-    "0b045197b94f8863": 1,
     "0b1dd9528bf9f4d7": 1,
+    "0bb960006757fa5d": 2,
     "0bf07eca2ad5d37a": 1,
     "0c15dec97c59fb17": 1,
+    "0c2d1ea4ed7d84e1": 1,
     "0c4aa6cdd20ff426": 1,
     "0c53a2dd00579986": 1,
     "0c6ad1b72d1c5abd": 1,
@@ -90,6 +91,7 @@
     "14c95e594f5e88c9": 1,
     "14f3cf459e8fd59e": 1,
     "14f4b594979ef4be": 1,
+    "15d5cc8200fcb115": 1,
     "15f6943efefbba82": 1,
     "15f72a1f46f3211c": 1,
     "163be34070c86587": 1,
@@ -155,7 +157,6 @@
     "29e2d3f4c6ced0a9": 1,
     "2a2ea864e10f10a0": 1,
     "2a6fba049050425f": 1,
-    "2a967d498d7ada65": 1,
     "2ad053ce77d6dfb2": 1,
     "2bef63e501d18ed2": 1,
     "2cce43ebc1614860": 1,
@@ -304,6 +305,7 @@
     "5977e81f73804251": 1,
     "59df1ab3f8808846": 1,
     "5ae402699aab9b4f": 1,
+    "5b49296fbe1a85c1": 1,
     "5b5f89cf29e631cb": 1,
     "5bb29ca2159fbdc5": 1,
     "5bcc598790149aed": 1,
@@ -341,7 +343,6 @@
     "658230c0c4b098a5": 1,
     "65c592402d3c35db": 1,
     "666a7f0d59bdfda9": 1,
-    "6698ef2d1387e09e": 1,
     "673cdefbc0e27446": 1,
     "67f863244c398a2e": 1,
     "686f4cbec8a0fd92": 1,
@@ -377,6 +378,7 @@
     "6eede9ab9fb16d7c": 1,
     "6efa92670898d4c4": 1,
     "7015815c99e52132": 1,
+    "7065dbb5645a57f7": 1,
     "70b546f19e61694e": 1,
     "70bd27545e44e77c": 1,
     "70e78f68bbb3f8b1": 1,
@@ -386,6 +388,7 @@
     "7155143a76ead712": 1,
     "7194ef683df831bc": 1,
     "729ecae0417d0f29": 1,
+    "72a9b264ea6e4f80": 1,
     "731af5ab97f97192": 1,
     "7348221dfe25068d": 1,
     "7383f1c75dba03da": 1,
@@ -465,6 +468,7 @@
     "8990b0dcf557805f": 1,
     "89b40759e47ca8db": 1,
     "89da94f6e3a69c7d": 1,
+    "8a2fbe60831c0ff1": 1,
     "8a46989d4cc28dc2": 1,
     "8a7412eb78a37817": 1,
     "8a79ca5fee4584ac": 1,
@@ -499,6 +503,7 @@
     "926d6280af25895e": 1,
     "929f55f8ba581bce": 1,
     "92a23a8351ac6f5b": 1,
+    "92c51ace17ce9e06": 1,
     "93ab56e01aefd998": 1,
     "93b9870af2c85e3c": 1,
     "943a5cceaaa0085d": 1,
@@ -516,7 +521,9 @@
     "9807478b48fb6f6a": 1,
     "98c9c3613c3d13da": 1,
     "98cf46d5ad809549": 1,
+    "98e56399e03423a5": 1,
     "98f0810d451927f1": 1,
+    "9901c04be163c8bf": 1,
     "99234a03fbba27b8": 1,
     "99a67420ab2fdabd": 2,
     "99ab2f421483cca1": 1,
@@ -525,6 +532,7 @@
     "9a358c85f07b6c11": 1,
     "9a6d3e40660da4b5": 1,
     "9aaacc3995d7f2de": 1,
+    "9ab6ff5266fa89da": 1,
     "9afaad4e059435eb": 1,
     "9b108a480389775d": 1,
     "9b2cd4682ff8f174": 1,
@@ -653,6 +661,7 @@
     "c27beabd28694361": 1,
     "c3312d7a632e3665": 1,
     "c377e5bc7e557f04": 1,
+    "c38bc63bccefdbac": 1,
     "c3d10f9320c71fb3": 1,
     "c4d921ac33389a47": 1,
     "c4e680d4321eb064": 1,
@@ -662,6 +671,7 @@
     "c6cce4bd6bf12d59": 1,
     "c780753c13cd3f21": 1,
     "c7f342c6c31cf572": 1,
+    "c865526eaff63e67": 1,
     "c8d00c6953c98eca": 1,
     "c958f2914094b197": 1,
     "c96ee9924b3f4ea7": 1,
@@ -689,6 +699,7 @@
     "ced45d1f3dfdf4bf": 1,
     "ceefd01b00d7a785": 1,
     "cf5d9fe2b8d23875": 1,
+    "d08941b3f1f42146": 1,
     "d13f1005c59d1243": 1,
     "d1debd6e7118e546": 1,
     "d20c4d175159aa90": 1,
@@ -737,6 +748,7 @@
     "e45d1d2fb94c859b": 1,
     "e4bc846ba130e160": 1,
     "e4c2843bfae3d310": 1,
+    "e53558b47dfffdd1": 1,
     "e539609f53bb27d3": 1,
     "e6460fb624a61900": 1,
     "e71da0387666d746": 1,
@@ -753,7 +765,6 @@
     "ea339e6d78da0f57": 1,
     "eaee9a41a0b130d0": 1,
     "eb0bbed02f67f613": 1,
-    "eb124ee954a17bd6": 1,
     "eb7e225d5bfe0159": 1,
     "ebec59933509b551": 1,
     "ebfb2fa4553fc40c": 1,
@@ -776,6 +787,7 @@
     "f05e80092b0c0382": 1,
     "f09e3e55245ee073": 1,
     "f102cbf1fab8a3d9": 1,
+    "f14901c53868eee4": 1,
     "f1812b941eb02542": 1,
     "f1f7493a31b45480": 1,
     "f23a5dc8edef52e2": 1,
diff --git a/tools/oracles/first-match-union.ts b/tools/oracles/first-match-union.ts
index b219f1bff..fabdce477 100644
--- a/tools/oracles/first-match-union.ts
+++ b/tools/oracles/first-match-union.ts
@@ -1,6 +1,6 @@
 // The parity oracle for the structural union first-match arm (ADR-0016).
 //
-// It decodes every value of tests/OpenCode.Sdk.Tests/Fixtures/Unions/first-match-corpus.json with
+// It decodes every value of tests/OpenCode.Sdk.Tests/Serialization/Fixtures/first-match-corpus.json with
 // upstream's own schemas and upstream's own Effect, then writes which union member took each value
 // to first-match-expected.json beside it. The SDK's parity test asserts that the generated
 // converters pick the same member. Re-run it when a refresh moves the pinned Effect version (the
@@ -18,7 +18,7 @@ import { fileURLToPath } from "node:url"
 const repository = join(dirname(fileURLToPath(import.meta.url)), "..", "..")
 const upstream = join(repository, "external", "opencode")
 const schemaPackage = join(upstream, "packages", "schema")
-const fixtures = join(repository, "tests", "OpenCode.Sdk.Tests", "Fixtures", "Unions")
+const fixtures = join(repository, "tests", "OpenCode.Sdk.Tests", "Serialization", "Fixtures")
 
 const { Schema } = await import(createRequire(join(schemaPackage, "package.json")).resolve("effect"))
 const reference = await import(join(schemaPackage, "src", "config", "reference.ts"))
diff --git a/tools/oracles/wildcard-path.ts b/tools/oracles/wildcard-path.ts
index b58d2811d..6dabbb440 100644
--- a/tools/oracles/wildcard-path.ts
+++ b/tools/oracles/wildcard-path.ts
@@ -1,7 +1,7 @@
 // The parity oracle for the trailing-wildcard route rule (fs.read).
 //
 // It calls upstream's own generated Promise client (packages/client/src/promise/generated/client.ts)
-// with a recording fetch, once per path of tests/OpenCode.Sdk.Tests/Fixtures/Routes/
+// with a recording fetch, once per path of tests/OpenCode.Sdk.Tests/FileSystem/Fixtures/
 // wildcard-path-corpus.json, and writes the request path the client produced to
 // wildcard-path-expected.json beside it. The SDK's route test asserts the generated route builder
 // produces the same path. Re-run it when a refresh moves the watched codegen rule
@@ -17,7 +17,7 @@ import { fileURLToPath } from "node:url"
 
 const repository = join(dirname(fileURLToPath(import.meta.url)), "..", "..")
 const upstream = join(repository, "external", "opencode")
-const fixtures = join(repository, "tests", "OpenCode.Sdk.Tests", "Fixtures", "Routes")
+const fixtures = join(repository, "tests", "OpenCode.Sdk.Tests", "FileSystem", "Fixtures")
 const { make } = await import(join(upstream, "packages", "client", "src", "promise", "generated", "client.ts"))
 
 const corpus: string[] = JSON.parse(readFileSync(join(fixtures, "wildcard-path-corpus.json"), "utf8"))