diff --git a/src/ui/MaterialPreviewRenderer.cpp b/src/ui/MaterialPreviewRenderer.cpp
index 00f2cb4..3d0b869 100644
--- a/src/ui/MaterialPreviewRenderer.cpp
+++ b/src/ui/MaterialPreviewRenderer.cpp
@@ -14,6 +14,7 @@
 #include <pxr/usd/usdLux/tokens.h>
 #include <pxr/usd/usdGeom/xformCommonAPI.h>
 #include <pxr/usd/usd/references.h>
+#include <pxr/usd/usd/editContext.h>
 #include <pxr/usd/sdf/assetPath.h>
 #include <pxr/usd/sdf/primSpec.h>
 #include <imgui.h>
@@ -48,6 +49,10 @@ void MaterialPreviewRenderer::EnsureInitialized() {
     if (m_initialized) return;
 
     m_previewStage = pxr::UsdStage::CreateInMemory();
+    // Everything authored here (sphere, lights, reference) must go to the
+    // root layer: the session layer is reserved for node-preview overrides
+    // and is wiped wholesale on every SetMaterial.
+    m_previewStage->SetEditTarget(pxr::UsdEditTarget(m_previewStage->GetRootLayer()));
     // Pin the up axis rather than inheriting the site fallback: the light
     // rig, dome-pole compensation, and camera framing all assume Y-up.
     pxr::UsdGeomSetStageUpAxis(m_previewStage, pxr::UsdGeomTokens->y);
@@ -112,14 +117,18 @@ void MaterialPreviewRenderer::SetMaterial(const pxr::UsdStageRefPtr& sourceStage
     // materials can be spread across sublayers. Referencing at the identical
     // path keeps internal connection paths valid without remapping, and
     // relative asset paths keep resolving against their original layers.
-    pxr::UsdPrim mirrorPrim = m_previewStage->OverridePrim(materialPath);
-    if (!mirrorPrim) {
-        LOG_ERROR("MaterialPreviewRenderer: failed to create override at " + materialPath.GetString());
-        return;
+    // Authored only when the material changes: the shared in-memory layers
+    // recompose live, so revision bumps need no re-referencing.
+    if (materialPath != m_materialPath) {
+        pxr::UsdPrim mirrorPrim = m_previewStage->OverridePrim(materialPath);
+        if (!mirrorPrim) {
+            LOG_ERROR("MaterialPreviewRenderer: failed to create override at " + materialPath.GetString());
+            return;
+        }
+        mirrorPrim.GetReferences().ClearReferences();
+        mirrorPrim.GetReferences().AddReference(
+            sourceStage->GetRootLayer()->GetIdentifier(), materialPath);
     }
-    mirrorPrim.GetReferences().ClearReferences();
-    mirrorPrim.GetReferences().AddReference(
-        sourceStage->GetRootLayer()->GetIdentifier(), materialPath);
 
     pxr::UsdPrim spherePrim = m_previewStage->GetPrimAtPath(kSpherePath);
     pxr::UsdShadeMaterial material(m_previewStage->GetPrimAtPath(materialPath));
@@ -131,20 +140,14 @@ void MaterialPreviewRenderer::SetMaterial(const pxr::UsdStageRefPtr& sourceStage
         pxr::UsdShadeMaterialBindingAPI::Apply(spherePrim).Bind(material);
 
     // ── Selected-node preview (Hypershade-style) ─────────────────────────
-    // Wipe any override left by a previous selection: the scratch wrapper
-    // shader and the local opinions on the material's surface outputs, all
-    // of which live only in the scratch stage's root layer.
-    pxr::SdfLayerHandle rootLayer = m_previewStage->GetRootLayer();
-    if (pxr::SdfPrimSpecHandle matSpec = rootLayer->GetPrimAtPath(materialPath)) {
-        if (pxr::SdfPrimSpecHandle wrapSpec =
-                rootLayer->GetPrimAtPath(materialPath.AppendChild(kNodePreviewShaderName)))
-            matSpec->RemoveNameChild(wrapSpec);
-        for (const char* outName : {"outputs:surface", "outputs:mtlx:surface"}) {
-            if (pxr::SdfPropertySpecHandle prop =
-                    rootLayer->GetPropertyAtPath(materialPath.AppendProperty(pxr::TfToken(outName))))
-                matSpec->RemoveProperty(prop);
-        }
-    }
+    // All node-preview overrides (the scratch wrapper shader and the local
+    // opinions on the material's surface outputs) live exclusively in the
+    // preview stage's session layer, which is stronger than the root layer's
+    // reference. Wiping them is then just clearing that layer — no per-spec
+    // surgery (RemoveNameChild/RemoveProperty) that could interact badly with
+    // Sdf's inert-spec cleanup, and no stale overrides on other materials.
+    pxr::SdfLayerHandle sessionLayer = m_previewStage->GetSessionLayer();
+    sessionLayer->Clear();
 
     // Route the material's surface through the selected node. Nodes outside
     // the material's subtree (possible in hand-authored cross-scope networks)
@@ -154,6 +157,8 @@ void MaterialPreviewRenderer::SetMaterial(const pxr::UsdStageRefPtr& sourceStage
         previewNodePath.HasPrefix(materialPath)) {
         pxr::UsdShadeShader nodeShader(m_previewStage->GetPrimAtPath(previewNodePath));
         if (nodeShader) {
+            pxr::UsdEditContext sessionEdit(m_previewStage,
+                                            pxr::UsdEditTarget(sessionLayer));
             pxr::UsdShadeConnectableAPI sourceApi = nodeShader.ConnectableAPI();
             pxr::TfToken sourceName(previewNodeOutput);
             if (!previewOutputIsTerminal) {