diff --git a/src/CHATGPT_API_WEB_VERSION.ts b/src/CHATGPT_API_WEB_VERSION.ts
index 8ba647c..ec86328 100644
--- a/src/CHATGPT_API_WEB_VERSION.ts
+++ b/src/CHATGPT_API_WEB_VERSION.ts
@@ -1,3 +1,3 @@
-const CHATGPT_API_WEB_VERSION = "v1.2.2";
+const CHATGPT_API_WEB_VERSION = "v1.3.0";
 
 export default CHATGPT_API_WEB_VERSION;
diff --git a/src/app.tsx b/src/app.tsx
index dee192c..47c3154 100644
--- a/src/app.tsx
+++ b/src/app.tsx
@@ -1,17 +1,22 @@
 import { useEffect, useState } from "preact/hooks";
 import "./global.css";
 
-import { Message } from "./chatgpt";
+import { calculate_token_length, Message } from "./chatgpt";
 import getDefaultParams from "./getDefaultParam";
 import ChatBOX from "./chatbox";
 import { options } from "./settings";
 
-import CHATGPT_API_WEB_VERSION from './CHATGPT_API_WEB_VERSION'
+import CHATGPT_API_WEB_VERSION from "./CHATGPT_API_WEB_VERSION";
+
+export interface ChatStoreMessage extends Message {
+  hide: boolean;
+  token: number;
+}
 
 export interface ChatStore {
   chatgpt_api_web_version: string;
   systemMessageContent: string;
-  history: Message[];
+  history: ChatStoreMessage[];
   postBeginIndex: number;
   tokenMargin: number;
   totalTokens: number;
@@ -86,7 +91,14 @@ export function App() {
     if (ret.model === undefined) ret.model = "gpt-3.5-turbo";
     if (ret.responseModelName === undefined) ret.responseModelName = "";
     if (ret.chatgpt_api_web_version === undefined)
-      ret.chatgpt_api_web_version = CHATGPT_API_WEB_VERSION;
+      // this is from old version becasue it is undefined,
+      // so no higher than v1.3.0
+      ret.chatgpt_api_web_version = "v1.2.2";
+    for (const message of ret.history) {
+      if (message.hide === undefined) message.hide = false;
+      if (message.token === undefined)
+        message.token = calculate_token_length(message.content);
+    }
     return ret;
   };
 
diff --git a/src/chatbox.tsx b/src/chatbox.tsx
index 938b8e9..b9666e1 100644
--- a/src/chatbox.tsx
+++ b/src/chatbox.tsx
@@ -1,7 +1,11 @@
 import { createRef } from "preact";
 import { StateUpdater, useEffect, useState } from "preact/hooks";
 import type { ChatStore } from "./app";
-import ChatGPT, { ChunkMessage, FetchResponse } from "./chatgpt";
+import ChatGPT, {
+  calculate_token_length,
+  ChunkMessage,
+  FetchResponse,
+} from "./chatgpt";
 import Message from "./message";
 import Settings from "./settings";
 
@@ -77,17 +81,16 @@ export default function ChatBOX(props: {
         setShowGenerating(false);
 
         // console.log("push to history", allChunkMessage);
+        const content = allChunkMessage.join("");
         chatStore.history.push({
           role: "assistant",
-          content: allChunkMessage.join(""),
+          content,
+          hide: false,
+          token: calculate_token_length(content),
         });
         // manually copy status from client to chatStore
         chatStore.maxTokens = client.max_tokens;
         chatStore.tokenMargin = client.tokens_margin;
-        chatStore.totalTokens =
-          client.total_tokens +
-          39 +
-          client.calculate_token_length(allChunkMessage.join(""));
         setChatStore({ ...chatStore });
         setGeneratingMessage("");
         setShowGenerating(false);
@@ -100,7 +103,12 @@ export default function ChatBOX(props: {
     const data = (await response.json()) as FetchResponse;
     chatStore.responseModelName = data.model ?? "";
     const content = client.processFetchResponse(data);
-    chatStore.history.push({ role: "assistant", content });
+    chatStore.history.push({
+      role: "assistant",
+      content,
+      hide: false,
+      token: data.usage.completion_tokens ?? calculate_token_length(content),
+    });
     setShowGenerating(false);
   };
 
@@ -109,11 +117,35 @@ export default function ChatBOX(props: {
     // manually copy status from chatStore to client
     client.apiEndpoint = chatStore.apiEndpoint;
     client.sysMessageContent = chatStore.systemMessageContent;
-    client.messages = chatStore.history.slice(chatStore.postBeginIndex);
+    client.tokens_margin = chatStore.tokenMargin;
+    client.messages = chatStore.history
+      .slice(chatStore.postBeginIndex)
+      // only copy non hidden message
+      .filter(({ hide }) => !hide)
+      // only copy content and role attribute to client for posting
+      .map(({ content, role }) => {
+        return {
+          content,
+          role,
+        };
+      });
     client.model = chatStore.model;
     client.max_tokens = chatStore.maxTokens;
-    // try forget message before sending request
-    client.forgetSomeMessages();
+
+    // todo move code
+    const max = chatStore.maxTokens - chatStore.tokenMargin;
+    let sum = 0;
+    chatStore.postBeginIndex = chatStore.history.filter(
+      ({ hide }) => !hide
+    ).length;
+    for (const msg of chatStore.history.slice().reverse()) {
+      sum += msg.token;
+      if (sum > max) break;
+      chatStore.postBeginIndex -= 1;
+    }
+    chatStore.postBeginIndex =
+      chatStore.postBeginIndex < 0 ? 0 : chatStore.postBeginIndex;
+
     try {
       setShowGenerating(true);
       const response = await client._fetch(chatStore.streamMode);
@@ -129,11 +161,21 @@ export default function ChatBOX(props: {
       chatStore.maxTokens = client.max_tokens;
       chatStore.tokenMargin = client.tokens_margin;
       chatStore.totalTokens = client.total_tokens;
-      // when total token > max token - margin token:
-      // ChatGPT will "forgot" some historical message
-      // so client.message.length will be less than chatStore.history.length
+
+      // todo move code
+      const max = chatStore.maxTokens - chatStore.tokenMargin;
+      let sum = 0;
+      chatStore.postBeginIndex = chatStore.history.filter(
+        ({ hide }) => !hide
+      ).length;
+      for (const msg of chatStore.history.slice().reverse()) {
+        sum += msg.token;
+        if (sum > max) break;
+        chatStore.postBeginIndex -= 1;
+      }
       chatStore.postBeginIndex =
-        chatStore.history.length - client.messages.length;
+        chatStore.postBeginIndex < 0 ? 0 : chatStore.postBeginIndex;
+
       console.log("postBeginIndex", chatStore.postBeginIndex);
       setChatStore({ ...chatStore });
     } catch (error) {
@@ -153,7 +195,12 @@ export default function ChatBOX(props: {
       return;
     }
     chatStore.responseModelName = "";
-    chatStore.history.push({ role: "user", content: inputMsg.trim() });
+    chatStore.history.push({
+      role: "user",
+      content: inputMsg.trim(),
+      hide: false,
+      token: calculate_token_length(inputMsg.trim()),
+    });
     // manually calculate token length
     chatStore.totalTokens += client.calculate_token_length(inputMsg.trim());
     client.total_tokens += client.calculate_token_length(inputMsg.trim());
@@ -191,7 +238,9 @@ export default function ChatBOX(props: {
             Tokens: {chatStore.totalTokens} / {chatStore.maxTokens}
           </span>{" "}
           <span>{chatStore.model}</span>{" "}
-          <span>Messages: {chatStore.history.length}</span>{" "}
+          <span>
+            Messages: {chatStore.history.filter(({ hide }) => !hide).length}
+          </span>{" "}
           <span>Cut: {chatStore.postBeginIndex}</span>
         </div>
       </p>
@@ -252,6 +301,23 @@ export default function ChatBOX(props: {
         {chatStore.responseModelName && (
           <p className="p-2 my-2 text-center opacity-50 dark:text-white">
             Generated by {chatStore.responseModelName}
+            {chatStore.postBeginIndex !== 0 && (
+              <>
+                <br />
+                提示：会话过长，已裁切前 {chatStore.postBeginIndex} 条消息
+              </>
+            )}
+            {chatStore.chatgpt_api_web_version < "v1.3.0" && (
+              <>
+                <br />
+                提示：当前会话版本 {chatStore.chatgpt_api_web_version}。
+                <br />
+                v1.3.0
+                引入与旧版不兼容的消息裁切算法。继续使用旧版可能会导致消息裁切过多或过少（表现为失去上下文或输出不完整）。
+                <br />
+                请在左上角创建新会话：）
+              </>
+            )}
           </p>
         )}
         {showRetry && (
diff --git a/src/message.tsx b/src/message.tsx
index 0ef04aa..d76a7b0 100644
--- a/src/message.tsx
+++ b/src/message.tsx
@@ -15,43 +15,71 @@ export default function Message(props: Props) {
         chat.role === "user" ? "left-0" : "right-0"
       }`}
       onClick={() => {
-        if (
-          confirm(
-            `Are you sure to delete this message?\n${chat.content.slice(
-              0,
-              39
-            )}...`
-          )
-        ) {
-          chatStore.history.splice(messageIndex, 1);
-          chatStore.postBeginIndex = Math.max(chatStore.postBeginIndex - 1, 0);
-          chatStore.totalTokens = Math.max(
-            0,
-            chatStore.totalTokens - calculate_token_length(chat.content)
-          );
-          setChatStore({ ...chatStore });
+        chatStore.history[messageIndex].hide =
+          !chatStore.history[messageIndex].hide;
+
+        // todo move code
+        const max = chatStore.maxTokens - chatStore.tokenMargin;
+        let sum = 0;
+        chatStore.postBeginIndex = chatStore.history.filter(
+          ({ hide }) => !hide
+        ).length;
+        for (const msg of chatStore.history.slice().reverse()) {
+          sum += msg.token;
+          if (sum > max) break;
+          chatStore.postBeginIndex -= 1;
         }
+        chatStore.postBeginIndex =
+          chatStore.postBeginIndex < 0 ? 0 : chatStore.postBeginIndex;
+
+        //chatStore.totalTokens =
+        chatStore.totalTokens = 0;
+        for (const i of chatStore.history
+          .filter(({ hide }) => !hide)
+          .slice(chatStore.postBeginIndex)
+          .map(({ token }) => token)) {
+          chatStore.totalTokens += i;
+        }
+        setChatStore({ ...chatStore });
       }}
     >
       🗑️
     </button>
   );
   return (
-    <div
-      className={`flex ${
-        chat.role === "assistant" ? "justify-start" : "justify-end"
-      }`}
-    >
+    <>
+      {chatStore.postBeginIndex !== 0 &&
+        !chatStore.history[messageIndex].hide &&
+        chatStore.postBeginIndex ===
+          chatStore.history.slice(0, messageIndex).filter(({ hide }) => !hide)
+            .length && (
+          <div className="flex items-center relative justify-center">
+            <hr className="w-full h-px my-4 border-0 bg-slate-800 dark:bg-white" />
+            <span className="absolute px-3 bg-slate-800 text-white rounded p-1 dark:bg-white dark:text-black">
+              Above messages are "forgotten"
+            </span>
+          </div>
+        )}
       <div
-        className={`relative w-fit p-2 rounded my-2 ${
-          chat.role === "assistant"
-            ? "bg-white dark:bg-gray-700 dark:text-white"
-            : "bg-green-400"
+        className={`flex ${
+          chat.role === "assistant" ? "justify-start" : "justify-end"
         }`}
       >
-        <p className="message-content">{chat.content}</p>
-        <DeleteIcon />
+        <div
+          className={`relative w-fit p-2 rounded my-2 ${
+            chat.role === "assistant"
+              ? "bg-white dark:bg-gray-700 dark:text-white"
+              : "bg-green-400"
+          } ${chat.hide ? "opacity-50" : ""}`}
+        >
+          <p className="message-content">
+            {chat.hide
+              ? chat.content.split("\n")[0].slice(0, 16) + "... (deleted)"
+              : chat.content}
+          </p>
+          <DeleteIcon />
+        </div>
       </div>
-    </div>
+    </>
   );
 }