diff --git a/packages/nodes/src/slab/geometry.ts b/packages/nodes/src/slab/geometry.ts
index 6b3c241db..b9ec1853f 100644
--- a/packages/nodes/src/slab/geometry.ts
+++ b/packages/nodes/src/slab/geometry.ts
@@ -122,7 +122,14 @@ function splitSlabFacesByFacing(geometry: BufferGeometry): {
   const build = (data: { pos: number[]; uv: number[] }) => {
     const geo = new BufferGeometry()
     geo.setAttribute('position', new Float32BufferAttribute(data.pos, 3))
-    if (data.uv.length > 0) geo.setAttribute('uv', new Float32BufferAttribute(data.uv, 2))
+    if (data.uv.length > 0) {
+      geo.setAttribute('uv', new Float32BufferAttribute(data.uv, 2))
+      // Slot finishes with an aoMap (e.g. the default woodplank) sample uv2;
+      // a referenced-but-missing attribute crashes the WebGPU renderer mid
+      // scene pass, which leaks the MRT render target and poisons every
+      // pipeline built afterwards.
+      geo.setAttribute('uv2', new Float32BufferAttribute(data.uv.slice(), 2))
+    }
     geo.computeVertexNormals()
     return geo
   }
diff --git a/packages/viewer/src/components/viewer/post-processing.tsx b/packages/viewer/src/components/viewer/post-processing.tsx
index 801b11742..44c05e3ca 100644
--- a/packages/viewer/src/components/viewer/post-processing.tsx
+++ b/packages/viewer/src/components/viewer/post-processing.tsx
@@ -598,6 +598,12 @@ const PostProcessingPasses = ({
       }
     } catch (error) {
       hasPipelineErrorRef.current = true
+      // A mid-pass exception (e.g. thrown inside a PassNode's scene render)
+      // leaves the pass's MRT render target bound on the renderer. Every
+      // pipeline compiled afterwards then validates against that 3-attachment
+      // framebuffer and fails, poisoning the rebuilt pipeline and the fallback
+      // path alike. Restore the default target before retrying.
+      ;(renderer as any).setRenderTarget?.(null)
       console.error('[viewer/post-processing] Render pass failed.', {
         retryCount: retryCountRef.current,
         rendererCtor: (renderer as any).constructor?.name,
diff --git a/packages/viewer/src/systems/roof/roof-system.tsx b/packages/viewer/src/systems/roof/roof-system.tsx
index 3a65665a2..45c44afeb 100644
--- a/packages/viewer/src/systems/roof/roof-system.tsx
+++ b/packages/viewer/src/systems/roof/roof-system.tsx
@@ -497,8 +497,10 @@ function updateMergedRoofGeometry(
 
   if (children.length === 0) {
     mergedMesh.geometry.dispose()
-    // Keep a valid position attribute so Drei's BVH can index safely.
-    mergedMesh.geometry = new THREE.BoxGeometry(0, 0, 0)
+    // Keep a valid position attribute so Drei's BVH can index safely. Must
+    // also carry uv2 — the roof finish's aoMap samples it, and a missing
+    // attribute crashes the WebGPU renderer (BoxGeometry has no uv2).
+    mergedMesh.geometry = ensureRenderableGeometryAttributes(new THREE.BufferGeometry())
     return
   }