fix(web): regenerate a single-chat answer as a new turn (#18202)

web/src/pages/next-chats/chat-stream/store.ts

@@ -44,7 +44,6 @@ export type ChatStreamState = {
   failStream(conversationId: string, pendingInput: string): void;
   consumePendingInput(conversationId: string): void;
   removeMessageById(conversationId: string, messageId: string): void;
-  truncateAfterMessage(conversationId: string, messageId: string): void;
   endStream(conversationId: string): void;
   stopStream(conversationId: string): void;
   removeSessions(conversationIds: string[]): void;
@@ -324,44 +323,6 @@ export const useChatStreamStore = create<ChatStreamState>()(
         );
       },
 
-      truncateAfterMessage: (conversationId, messageId) => {
-        if (!conversationId) return;
-        set(
-          (state) => {
-            const previous = state.sessions[conversationId];
-            if (!previous) return state;
-
-            const index = previous.messages.findIndex(
-              (x) => x.id === messageId,
-            );
-            if (index === -1) return state;
-
-            const kept = previous.messages.slice(0, index + 2);
-            const latest = kept.at(-1);
-            const messages = latest
-              ? [
-                  ...kept.slice(0, -1),
-                  {
-                    ...latest,
-                    content: '',
-                    reference: undefined,
-                    prompt: undefined,
-                  },
-                ]
-              : kept;
-
-            return {
-              sessions: {
-                ...state.sessions,
-                [conversationId]: { ...previous, messages },
-              },
-            };
-          },
-          false,
-          'truncateAfterMessage',
-        );
-      },
-
       endStream: (conversationId) => {
         if (!conversationId) return;
         set(

web/src/pages/next-chats/hooks/use-send-chat-message.ts

@@ -2,11 +2,10 @@ import { NextMessageInputOnPressEnterParameter } from '@/components/message-inpu
 import { MessageType } from '@/constants/chat';
 import {
   useHandleMessageInputChange,
-  useRegenerateMessage,
   useScrollToBottom,
 } from '@/hooks/logic-hooks';
 import { useGetChatSearchParams } from '@/hooks/use-chat-request';
-import { IMessage } from '@/interfaces/database/chat';
+import { IMessage, Message } from '@/interfaces/database/chat';
 import notification from '@/utils/notification';
 import { trim } from 'lodash';
 import { useCallback, useEffect, useRef } from 'react';
@@ -83,9 +82,6 @@ export const useSendMessage = () => {
   const removeMessageFromStore = useChatStreamStore(
     (state) => state.removeMessageById,
   );
-  const truncateAfterMessage = useChatStreamStore(
-    (state) => state.truncateAfterMessage,
-  );
   const hydrateFromServer = useChatStreamStore(
     (state) => state.hydrateFromServer,
   );
@@ -138,13 +134,6 @@ export const useSendMessage = () => {
     setValue(pendingInput);
   }, [pendingInput, value, conversationId, consumePendingInput, setValue]);
 
-  const removeMessagesAfterCurrentMessage = useCallback(
-    (messageId: string) => {
-      truncateAfterMessage(conversationId, messageId);
-    },
-    [conversationId, truncateAfterMessage],
-  );
-
   const removeMessageById = useCallback(
     (messageId: string) => {
       removeMessageFromStore(conversationId, messageId);
@@ -152,11 +141,25 @@ export const useSendMessage = () => {
     [conversationId, removeMessageFromStore],
   );
 
-  const { regenerateMessage } = useRegenerateMessage({
-    removeMessagesAfterCurrentMessage,
-    sendMessage,
-    messages,
-  });
+  // Regenerating re-asks the same question as a new turn instead of rewriting
+  // the original exchange, so every earlier answer stays in the transcript.
+  const regenerateMessage = useCallback(
+    (message: Message) => {
+      if (isStreaming) return;
+
+      const questionMessage: IMessage = {
+        content: message.content,
+        files: message.files,
+        id: uuid(),
+        role: MessageType.User,
+        conversationId,
+      };
+
+      appendQuestion(conversationId, questionMessage);
+      sendMessage({ message: questionMessage });
+    },
+    [conversationId, isStreaming, appendQuestion, sendMessage],
+  );
 
   const { createConversationBeforeSendMessage } =
     useCreateConversationBeforeSendMessage();