feat: order streams by last child creation

js/src/lib/firestore-particles.ts

@@ -58,6 +58,7 @@ const particleConverter: FirestoreDataConverter<Particle> = {
               ]),
             )
             : undefined,
+          last_child_created_at: raw.last_child_created_at ? (raw.last_child_created_at as Timestamp).toDate() : undefined,
         });
       case "folder":
         return ParticleSchema.parse({
@@ -127,8 +128,10 @@ export function subscribeToParticleChildren(
   collectionPath: string,
   onData: (children: Particle[]) => void,
   onError: (error: Error) => void,
+  orderByField: string = "created_at",
+  orderDirection: "asc" | "desc" = "desc",
 ): Unsubscribe {
-  const q = query(typedCollection(collectionPath), orderBy("created_at"));
+  const q = query(typedCollection(collectionPath), orderBy(orderByField, orderDirection));
   return onSnapshot(
     q,
     (snap) => {
@@ -222,3 +225,27 @@ export async function updateParticleVisibleTo(
     updated_at: serverTimestamp(),
   });
 }
+
+// CAUTION: use the other type safe update functions in most cases
+// There is no checking whether this field actually exists on the particle type, so it can lead to inconsistent data if used incorrectly
+export async function updateParticle(
+  docPath: string,
+  fieldName: string,
+  value: any,
+): Promise<void> {
+  const particleRef = typedDoc(docPath);
+  await updateDoc(particleRef, {
+    [fieldName]: value,
+    updated_at: serverTimestamp(),
+  });
+}
+
+export async function updateStreamParticleLastChildParticle(
+  docPath: string,
+): Promise<void> {
+  const particleRef = typedDoc(docPath);
+  await updateDoc(particleRef, {
+    last_child_created_at: serverTimestamp(),
+    updated_at: serverTimestamp(),
+  });
+}