diff --git a/apps/editor/app/viewer/[id]/page.tsx b/apps/editor/app/viewer/[id]/page.tsx
index a21f97d3..8d06101b 100644
--- a/apps/editor/app/viewer/[id]/page.tsx
+++ b/apps/editor/app/viewer/[id]/page.tsx
@@ -28,6 +28,10 @@ export default function ViewerPage() {
   const [canShowGuides, setCanShowGuides] = useState(true)
   const setScene = useScene((state) => state.setScene)
 
+  useEffect(() => {
+    useViewer.getState().setProjectId(projectId)
+  }, [projectId])
+
   useEffect(() => {
     const loadContent = async () => {
       try {
diff --git a/apps/editor/components/editor/index.tsx b/apps/editor/components/editor/index.tsx
index 56627adc..161d4ddb 100644
--- a/apps/editor/components/editor/index.tsx
+++ b/apps/editor/components/editor/index.tsx
@@ -71,6 +71,14 @@ export default function Editor({ projectId }: EditorProps) {
   const isSceneLoading = useProjectStore((state) => state.isSceneLoading)
   const isLoading = isProjectLoading || isSceneLoading
 
+  useEffect(() => {
+    if (projectId) {
+      useViewer.getState().setProjectId(projectId)
+    } else {
+      useViewer.getState().setProjectId(null)
+    }
+  }, [projectId])
+
   useEffect(() => {
     document.body.classList.add('dark')
     return () => {
diff --git a/packages/viewer/src/components/renderers/guide/guide-renderer.tsx b/packages/viewer/src/components/renderers/guide/guide-renderer.tsx
index 10a50c49..ced9b464 100644
--- a/packages/viewer/src/components/renderers/guide/guide-renderer.tsx
+++ b/packages/viewer/src/components/renderers/guide/guide-renderer.tsx
@@ -5,15 +5,17 @@ import { DoubleSide, type Group, type Texture, TextureLoader } from 'three'
 import { float, texture } from 'three/tsl'
 import { MeshBasicNodeMaterial } from 'three/webgpu'
 import { useAssetUrl } from '../../../hooks/use-asset-url'
+import useViewer from '../../../store/use-viewer'
 
 export const GuideRenderer = ({ node }: { node: GuideNode }) => {
+  const showGuides = useViewer((s) => s.showGuides)
   const ref = useRef<Group>(null!)
   useRegistry(node.id, 'guide', ref)
 
   const resolvedUrl = useAssetUrl(node.url)
 
   return (
-    <group ref={ref} position={node.position} rotation={[0, node.rotation[1], 0]}>
+    <group ref={ref} visible={showGuides} position={node.position} rotation={[0, node.rotation[1], 0]}>
       {resolvedUrl && (
         <Suspense>
           <GuidePlane url={resolvedUrl} scale={node.scale} opacity={node.opacity} />
diff --git a/packages/viewer/src/components/renderers/scan/scan-renderer.tsx b/packages/viewer/src/components/renderers/scan/scan-renderer.tsx
index d186c9b4..e631c173 100644
--- a/packages/viewer/src/components/renderers/scan/scan-renderer.tsx
+++ b/packages/viewer/src/components/renderers/scan/scan-renderer.tsx
@@ -3,8 +3,10 @@ import { Suspense, useMemo, useRef } from 'react'
 import type { Group, Material, Mesh } from 'three'
 import { useAssetUrl } from '../../../hooks/use-asset-url'
 import { useGLTFKTX2 } from '../../../hooks/use-gltf-ktx2'
+import useViewer from '../../../store/use-viewer'
 
 export const ScanRenderer = ({ node }: { node: ScanNode }) => {
+  const showScans = useViewer((s) => s.showScans)
   const ref = useRef<Group>(null!)
   useRegistry(node.id, 'scan', ref)
 
@@ -13,6 +15,7 @@ export const ScanRenderer = ({ node }: { node: ScanNode }) => {
   return (
     <group
       ref={ref}
+      visible={showScans}
       position={node.position}
       rotation={node.rotation}
       scale={[node.scale, node.scale, node.scale]}
diff --git a/packages/viewer/src/store/use-viewer.ts b/packages/viewer/src/store/use-viewer.ts
index 9c3266b8..e10beb1c 100644
--- a/packages/viewer/src/store/use-viewer.ts
+++ b/packages/viewer/src/store/use-viewer.ts
@@ -47,6 +47,10 @@ type ViewerState = {
   showGuides: boolean
   setShowGuides: (show: boolean) => void
 
+  projectId: string | null
+  setProjectId: (id: string | null) => void
+  projectPreferences: Record<string, { showScans?: boolean, showGuides?: boolean }>
+
   // Smart selection update
   setSelection: (updates: Partial<SelectionPath>) => void
   resetSelection: () => void
@@ -80,10 +84,43 @@ const useViewer = create<ViewerState>()(
       setWallMode: (mode) => set({ wallMode: mode }),
 
       showScans: true,
-      setShowScans: (show) => set({ showScans: show }),
+      setShowScans: (show) =>
+        set((state) => {
+          const projectPreferences = { ...(state.projectPreferences || {}) };
+          if (state.projectId) {
+            projectPreferences[state.projectId] = {
+              ...(projectPreferences[state.projectId] || {}),
+              showScans: show,
+            };
+          }
+          return { showScans: show, projectPreferences };
+        }),
 
       showGuides: true,
-      setShowGuides: (show) => set({ showGuides: show }),
+      setShowGuides: (show) =>
+        set((state) => {
+          const projectPreferences = { ...(state.projectPreferences || {}) };
+          if (state.projectId) {
+            projectPreferences[state.projectId] = {
+              ...(projectPreferences[state.projectId] || {}),
+              showGuides: show,
+            };
+          }
+          return { showGuides: show, projectPreferences };
+        }),
+
+      projectId: null,
+      setProjectId: (id) =>
+        set((state) => {
+          if (!id) return { projectId: id };
+          const prefs = state.projectPreferences?.[id] || {};
+          return {
+            projectId: id,
+            showScans: prefs.showScans ?? true,
+            showGuides: prefs.showGuides ?? true,
+          };
+        }),
+      projectPreferences: {},
 
       setSelection: (updates) =>
         set((state) => {
@@ -130,8 +167,7 @@ const useViewer = create<ViewerState>()(
         cameraMode: state.cameraMode,
         levelMode: state.levelMode,
         wallMode: state.wallMode,
-        showScans: state.showScans,
-        showGuides: state.showGuides,
+        projectPreferences: state.projectPreferences,
       }),
     },
   ),