diff --git a/NucleicBroker/Wslc/WslcFacade.cs b/NucleicBroker/Wslc/WslcFacade.cs
index 34fae74..06bd7ea 100644
--- a/NucleicBroker/Wslc/WslcFacade.cs
+++ b/NucleicBroker/Wslc/WslcFacade.cs
@@ -27,10 +27,13 @@ namespace NucleicBroker.Wslc;
 // is the VM GUID an AF_HYPERV bind needs. Both IDLs are in the open-source WSL repo. The
 // internal one carries an explicit "ABI breaking changes are OK" warning.
 //
-// So there are two ways to close the gaps — direct internal COM, or shelling out to
-// `wslc.exe` — with a real stability-versus-fidelity trade-off between them, and it has NOT
-// been decided. §13.1 lays it out. Whichever wins lives entirely inside this class: `IWslc`
-// does not change, so nothing on the Swift side knows which surface answered.
+// D13 (§13.1): this class binds BOTH surfaces — compat SDK for everything it covers, internal
+// COM for those five. Shelling out to `wslc.exe` was considered and rejected (a spawn per call,
+// scraped text, no events, a second mechanism to maintain). Because the internal ABI is
+// explicitly unstable, bind it defensively: probe at startup, report what bound in the
+// `capabilities` hello, and degrade — losing reattach, stats and the Terminal panel — rather
+// than failing the sandbox. All of that lives inside this class: `IWslc` does not change, so
+// nothing on the Swift side knows which surface answered.
 //
 // Also note: `ProcessSettings` has no uid/gid, so exec wraps argv in setpriv/su — which
 // §3.2 already anticipated as the fallback, so it costs nothing.
diff --git a/spikes/README.md b/spikes/README.md
index 3d27fa4..d1aefed 100644
--- a/spikes/README.md
+++ b/spikes/README.md
@@ -67,9 +67,9 @@ for, and nothing above it should move. These three are different:
 
 | Finding | Consequence |
 | --- | --- |
-| No container enumeration, stats, pty or attach in the SDK | **Not fatal, and not CLI-only.** `wslcsdk.dll` wraps `WSLCCompat.idl` (the stable SDK surface), which genuinely lacks them; they all exist on `wslc.idl`, the service-internal COM interface `wslc.exe` calls — `ListContainers`, `Stats`, `ResizeTty`, `OpenContainer`/`Attach`, `OpenSessionByName`, and `IWSLCVirtualMachine::GetId` (the VM GUID for AF_HYPERV). Both IDLs are open source. Internal COM vs. CLI is an undecided trade-off — see §13.1. |
-| No create-or-attach on `Session` | **Answered:** `IWSLCSessionManager::OpenSessionByName` / `EnterSession` / `ListSessions` exist on the internal interface. Reattach (§2.3) is mechanically possible; what remains is choosing the surface. |
-| No gateway address anywhere on the API | Source it from `GetAdaptersAddresses` over the `vEthernet (WSL)` adapter — **or skip TCP entirely**: `IWSLCVirtualMachine::GetId` returns the VM GUID, so §5's AF_HYPERV/AF_VSOCK path (true vsock parity with macOS) is directly reachable rather than being upside. |
+| No container enumeration, stats, pty or attach in the SDK | **Settled by D13.** `wslcsdk.dll` wraps `WSLCCompat.idl` (the stable SDK surface), which genuinely lacks them; they all exist on `wslc.idl`, the service-internal COM interface `wslc.exe` calls — `ListContainers`, `Stats`, `ResizeTty`, `OpenContainer`/`Attach`, `OpenSessionByName`, and `IWSLCVirtualMachine::GetId`. The broker binds both surfaces; no CLI. |
+| No create-or-attach on `Session` | **Answered:** `IWSLCSessionManager::OpenSessionByName` / `EnterSession` / `ListSessions` on the internal interface. §2.3 reattach has its mechanism. |
+| No gateway address anywhere on the API | **Skip TCP:** `IWSLCVirtualMachine::GetId` returns the VM GUID, so §5's AF_HYPERV/AF_VSOCK path (true vsock parity with macOS) should become primary at M1 (b). Gateway TCP stays as fallback, its address from `GetAdaptersAddresses` over `vEthernet (WSL)`. |
 | No uid on `ProcessSettings` | Recoverable, and already planned for: exec wraps argv in `setpriv`/`su agent -c`. Interceptors and nash don't care about the numeric uid (§3.2). |
 
 ---
@@ -82,6 +82,9 @@ for, and nothing above it should move. These three are different:
   mounted vs. in-VM). Deliberately held back until `WslcApiDump` has run: written now, against
   guessed names, it would not compile, and fixing it blind is the mistake this whole approach
   exists to avoid.
-- **`HvSocketSpike`** — M1 (b): AF_HYPERV host listener ↔ AF_VSOCK dial from inside a wslc
-  container, plus gateway-TCP reachability and default-firewall behaviour in NAT and mirrored
-  modes. Only worth building once a container can be started at all.
+- **`HvSocketSpike`** — M1 (b), and now the *primary* control-plane spike rather than the
+  fallback one (D13): bind an AF_HYPERV listener on the VM GUID from
+  `IWSLCVirtualMachine::GetId` and dial AF_VSOCK from inside a wslc container. If vsock
+  traverses the container's namespaces, the Windows control plane gets true parity with macOS
+  and §5's firewall/NAT variance stops mattering. Measure gateway-TCP reachability in the same
+  run so the fallback stays evidenced.