diff --git a/js/desktop/src/api/types.ts b/js/desktop/src/api/types.ts
index 90cfbe2..03807d1 100644
--- a/js/desktop/src/api/types.ts
+++ b/js/desktop/src/api/types.ts
@@ -244,6 +244,9 @@ export const ParticleSchema = z.discriminatedUnion('type', [
     // e.g. ["human:human_xxxx", "human:human_yyyy"] - visible only to Aron and John
     // e.g. ["network:123"] - visible to everyone in the network
     visible_to: z.array(z.string()),
+    // Set to created_at on creation, bumped when children are added — keeps
+    // folders present in activity-ordered container queries.
+    last_child_created_at: z.coerce.date().optional(),
   }),
   ParticleBaseSchema.extend({
     type: z.literal('media'),
diff --git a/js/desktop/src/features/particles/particle-view-resolver.tsx b/js/desktop/src/features/particles/particle-view-resolver.tsx
index 2770522..bb3be17 100644
--- a/js/desktop/src/features/particles/particle-view-resolver.tsx
+++ b/js/desktop/src/features/particles/particle-view-resolver.tsx
@@ -7,6 +7,7 @@ import { useLiveParticle } from '@/hooks/use-particle';
 import { particlePath, type ParticlePath } from '@/lib/particle-path';
 import { Button } from '@/components/ui/button';
 
+import Layout from '@/features/layout';
 import { StreamView } from '@/features/particles/stream-view';
 import { FolderView } from '@/features/particles/folder-view';
 import { MediaParticleView } from '@/features/particles/media-particle-view';
@@ -32,9 +33,11 @@ export default function ParticleViewResolver() {
 
   if (isLoading) {
     return (
-      <div className="flex h-full items-center justify-center">
-        <p className="text-muted-foreground text-sm">Loading...</p>
-      </div>
+      <Layout>
+        <div className="flex h-full items-center justify-center">
+          <p className="text-muted-foreground text-sm">Loading...</p>
+        </div>
+      </Layout>
     );
   }
 
@@ -42,21 +45,33 @@ export default function ParticleViewResolver() {
     // Errors here are almost always Firestore permission-denied — the user lost
     // access to the network or to a custom-visibility particle. The React Router
     // stays on the dead route, so without an explicit escape the user is stuck.
-    return <InaccessibleParticle />;
+    return (
+      <Layout>
+        <InaccessibleParticle />
+      </Layout>
+    );
   }
 
+  // Streams render their own full-screen chrome; folders and leaves live
+  // inside the app Layout (breadcrumbs, full-height column) like the root.
   switch (particle.type) {
     case 'stream':
       return <StreamView streamParticle={particle} path={path} />;
     case 'folder':
-      return <FolderView folderParticle={particle} path={path} />;
+      return (
+        <Layout>
+          <FolderView folderParticle={particle} path={path} />
+        </Layout>
+      );
     default:
       return (
-        <LeafParticleView
-          particle={particle}
-          containerPath={particlePath(networkId, segments.slice(0, -1))}
-          networkId={networkId}
-        />
+        <Layout>
+          <LeafParticleView
+            particle={particle}
+            containerPath={particlePath(networkId, segments.slice(0, -1))}
+            networkId={networkId}
+          />
+        </Layout>
       );
   }
 }
@@ -133,7 +148,7 @@ function LeafParticleView({
   })();
 
   return (
-    <div className="h-full bg-black text-white [--stream-safe-top:4rem] [--stream-safe-bottom:2rem]">
+    <div className="min-h-0 flex-1 bg-black text-white [--stream-safe-top:2rem] [--stream-safe-bottom:2rem]">
       {content}
     </div>
   );
diff --git a/js/desktop/src/hooks/use-container-children.ts b/js/desktop/src/hooks/use-container-children.ts
index 06e7462..81f8db6 100644
--- a/js/desktop/src/hooks/use-container-children.ts
+++ b/js/desktop/src/hooks/use-container-children.ts
@@ -28,7 +28,10 @@ interface UseContainerChildrenResult {
 }
 
 function activityTime(particle: Particle): number {
-  if (particle.type === 'stream' && particle.last_child_created_at) {
+  if (
+    (particle.type === 'stream' || particle.type === 'folder') &&
+    particle.last_child_created_at
+  ) {
     return particle.last_child_created_at.getTime();
   }
   return particle.created_at.getTime();
diff --git a/js/desktop/src/lib/firestore-particles.ts b/js/desktop/src/lib/firestore-particles.ts
index a0377c6..4bcf8ef 100644
--- a/js/desktop/src/lib/firestore-particles.ts
+++ b/js/desktop/src/lib/firestore-particles.ts
@@ -116,6 +116,9 @@ const particleConverter: FirestoreDataConverter<Particle> = {
             ? (raw.updated_at as Timestamp).toDate()
             : undefined,
           visible_to: raw.visible_to,
+          last_child_created_at: raw.last_child_created_at
+            ? (raw.last_child_created_at as Timestamp).toDate()
+            : undefined,
         });
       case 'media':
       case 'file':
@@ -281,6 +284,25 @@ export function subscribeToLatestChild(
   );
 }
 
+// Best-effort bump of the parent container's last_child_created_at when a
+// child is created. The particle processor worker does this for stream
+// parents, but skips folders, so the client keeps folder activity fresh
+// itself. Same value semantics as the worker: the child's created_at, so it
+// stays directly comparable with playback markers.
+function bumpParentLastChildCreatedAt(
+  collectionPath: string,
+  childCreatedAt: Date,
+): void {
+  const parentDocPath = collectionPath.replace(/\/children$/, '');
+  // The network root (networks/{id}) is not a particle doc — nothing to bump.
+  if (!parentDocPath.includes('/children/')) return;
+  updateDoc(doc(firestoreDb, parentDocPath), {
+    last_child_created_at: Timestamp.fromDate(childCreatedAt),
+  }).catch(() => {
+    // Non-fatal: ordering freshness only.
+  });
+}
+
 // This creates a new particle document with the given properties and returns its ID.
 export async function createParticle<T extends ParticleType>(
   collectionPath: string,
@@ -296,15 +318,21 @@ export async function createParticle<T extends ParticleType>(
     );
   }
 
+  const createdAt = new Date();
   const particle: Particle = ParticleSchema.parse({
     id: '', // ignored by toFirestore, but needed to satisfy the type
     type,
     properties,
-    created_at: new Date(),
+    created_at: createdAt,
     created_by_human_id: createdByHumanId,
     ...(visibleTo ? { visible_to: visibleTo } : {}),
+    // Containers start with last_child_created_at = created_at so they appear
+    // in activity-ordered queries before they have any children (Firestore
+    // orderBy drops docs missing the field).
+    ...(isContainerType(type) ? { last_child_created_at: createdAt } : {}),
   });
   const ref = await addDoc(typedCollection(collectionPath), particle);
+  bumpParentLastChildCreatedAt(collectionPath, createdAt);
   return ref.id;
 }
 
@@ -318,15 +346,18 @@ export async function createStreamParticle(
     throw new Error('visibleTo is required for streams and cannot be empty');
   }
 
+  const createdAt = new Date();
   const particle: Particle = ParticleSchema.parse({
     id: '',
     type: 'stream',
     properties,
-    created_at: new Date(),
+    created_at: createdAt,
     created_by_human_id: createdByHumanId,
     visible_to: visibleTo,
+    last_child_created_at: createdAt,
   });
   const ref = await addDoc(typedCollection(collectionPath), particle);
+  bumpParentLastChildCreatedAt(collectionPath, createdAt);
   return ref.id;
 }