diff --git a/src/api/acts/roomContent.ts b/src/api/acts/roomContent.ts
index 8b3484c..5e8fbff 100644
--- a/src/api/acts/roomContent.ts
+++ b/src/api/acts/roomContent.ts
@@ -1,10 +1,11 @@
-import { and, coalesce, eq, insert, leftJoinOn, leftJoinUsing, max, order, plus, remove, select, update } from "dblang";
+import { and, coalesce, eq, insert, le, leftJoinOn, leftJoinUsing, max, order, plus, remove, select, update } from "dblang";
 import { checkSelfTag } from "../../server/outbagURL.js";
 import { Act, Client, STATE } from "../user.js";
 import { db, listCategories, listItems, listProducts } from "../../sys/db.js";
 import { isCategoryInRoom, isItemInRoom, isProductInRoom, isRoomDataFull } from "../helper.js"
 import { ROOM_RIGHTS } from "../../server/permissions.js";
 import { act_error } from "../../server/errors.js";
+import { uts } from "../../sys/tools.js";
 
 export const getCategories: Act = {
     state: STATE.client | STATE.remote,
@@ -716,6 +717,7 @@ export const changeItemState: Act = {
         if (!isItemInRoom(roomID, data.listItemID)) return void aws("error", act_error.ITEM_NOT_EXISTS);
         let req = await update(listItems)
             .set(listItems.state, data.state)
+            .set(listItems.lastStateTime, uts())
             .where(and(
                 eq(listItems.listItemID, data.listItemID),
                 eq(listItems.roomID, roomID)
@@ -726,6 +728,50 @@ export const changeItemState: Act = {
     }
 };
 
+export const changeItemStates: Act = {
+    state: STATE.client | STATE.remote,
+    right: 0,
+    data: {
+        room: "string",
+        server: "string",
+        listItemIDs: "array-number",
+        changedTimes: "array-number", //in uts time sec
+        states: "array-number", // 0 = added; 1 = in cart/bought
+    },
+    func: async (client: Client, data: any, aws: (code: string, data: any) => void) => {
+        if (!checkSelfTag(data.server)) {
+            if (client.state != STATE.client) return void aws("error", act_error.RECURSION);
+            let resp = await client.pass(data.server, "changeItemStates", data);
+            aws(resp.state, resp.data);
+            return;
+        }
+        let roomID = await client.isInRoom(data.room);
+        if (roomID == -1) {
+            aws("error", act_error.NOT_IN_ROOM);
+            return;
+        }
+        if (
+            data.listItemIDs.length != data.changedTimes.length
+            || data.changedTimes.length != data.states.length
+        ) return void aws("error", "data");
+        for (let i = 0; i < data.listItemIDs.length; i++) {
+            let id = data.listItemIDs[i];
+            let time = data.changedTimes[i];
+            let state = data.states[i] == 0 ? 0 : 1;
+            await update(listItems)
+                .set(listItems.state, state)
+                .set(listItems.lastStateTime, uts())
+                .where(and(
+                    eq(listItems.listItemID, id),
+                    eq(listItems.roomID, roomID),
+                    le(listItems.lastStateTime, time)
+                ))
+                .query(db);
+        }
+        aws("ok", "");
+    }
+};
+
 export const deleteItem: Act = {
     state: STATE.client | STATE.remote,
     right: 0,
diff --git a/src/sys/db.ts b/src/sys/db.ts
index b5b9607..d2230d6 100644
--- a/src/sys/db.ts
+++ b/src/sys/db.ts
@@ -230,6 +230,7 @@ listItems.addAttributes({
         }
     },
     state: { type: SMALLINT, default: 0 },
+    lastStateTime: { type: BIGINT, default: 0 },
     title: { type: TEXT },
     description: { type: TEXT },
     category: {