refactor: simplify chat fork flow

src/components/chat/AgentTurn.tsx

@@ -23,17 +23,14 @@ import {
 import type { Theme } from "@mui/material/styles";
 import ContentCopyRounded from "@mui/icons-material/ContentCopyRounded";
 import RefreshRounded from "@mui/icons-material/RefreshRounded";
-import EditRounded from "@mui/icons-material/EditRounded";
+import { TbArrowsSplit2 } from "react-icons/tb";
-import CloseRounded from "@mui/icons-material/CloseRounded";
-import ChevronLeftRounded from "@mui/icons-material/ChevronLeftRounded";
-import ChevronRightRounded from "@mui/icons-material/ChevronRightRounded";
 import {
   parseAssistantMessageSections,
   parseContentWithToolCalls,
   type ContentSegment,
 } from "./chatMessageSections";
 import markdownStyles from "./GlobalChatboxMarkdown.module.css";
-import type { BranchState, Message, SpeechState } from "./GlobalChatbox.types";
+import type { Message, SpeechState } from "./GlobalChatbox.types";
 import { stripMarkdown } from "./GlobalChatbox.utils";
 import { AgentProgressTimeline } from "./AgentProgressTimeline";
 import { ChatInlineChart } from "./ChatInlineChart";
@@ -45,7 +42,6 @@ import VolumeUpRounded from "@mui/icons-material/VolumeUpRounded";
 import PauseRounded from "@mui/icons-material/PauseRounded";
 import PlayArrowRounded from "@mui/icons-material/PlayArrowRounded";
 import StopRounded from "@mui/icons-material/StopRounded";
-import SendRounded from "@mui/icons-material/SendRounded";
 import VerifiedUserRounded from "@mui/icons-material/VerifiedUserRounded";
 import TerminalRounded from "@mui/icons-material/TerminalRounded";
 import FolderOpenRounded from "@mui/icons-material/FolderOpenRounded";
@@ -58,24 +54,34 @@ import type { PermissionReply } from "@/lib/chatStream";
 
 type AgentTurnProps = {
   message: Message;
-  branchState?: BranchState;
   messageSpeechState: SpeechState;
   onSpeak: (messageId: string, text: string) => void;
   onPause: () => void;
   onResume: () => void;
   onStopSpeech: () => void;
   isTtsSupported: boolean;
-  onRegenerate: () => void;
+  onRegenerate: (messageId: string) => void;
-  onEditResubmit: (messageId: string, newContent: string) => void;
+  onCreateBranch: (messageId: string) => void;
-  onCycleBranch: (rootMessageId: string, direction: -1 | 1) => void;
   onReplyPermission: (requestId: string, reply: PermissionReply) => void;
 };
 
-const MarkdownBlock = ({ children }: { children: string }) => (
+const normalizeClipboardText = (value: string) => value.replace(/\s+$/u, "");
-  <div className={markdownStyles.markdown}>
+
+const MarkdownBlock = ({ children }: { children: string }) => {
+  const handleCopy = React.useCallback((event: React.ClipboardEvent<HTMLDivElement>) => {
+    const selectedText = window.getSelection()?.toString();
+    if (!selectedText) return;
+
+    event.preventDefault();
+    event.clipboardData.setData("text/plain", normalizeClipboardText(selectedText));
+  }, []);
+
+  return (
+    <div className={markdownStyles.markdown} onCopy={handleCopy}>
       <ReactMarkdown remarkPlugins={[remarkGfm]}>{children}</ReactMarkdown>
     </div>
-);
+  );
+};
 
 const formatMetadataValue = (value: unknown) => {
   if (typeof value === "string") {
@@ -667,7 +673,6 @@ const PermissionRequestGroup = ({
 export const AgentTurn = React.memo(
   ({
     message,
-    branchState,
     messageSpeechState,
     onSpeak,
     onPause,
@@ -675,17 +680,13 @@ export const AgentTurn = React.memo(
     onStopSpeech,
     isTtsSupported,
     onRegenerate,
-    onEditResubmit,
+    onCreateBranch,
-    onCycleBranch,
     onReplyPermission,
   }: AgentTurnProps) => {
     const theme = useTheme();
     const isUser = message.role === "user";
     const isErrorMessage = Boolean(message.isError);
     const [isHovered, setIsHovered] = React.useState(false);
-    const [isEditing, setIsEditing] = React.useState(false);
-    const [editDraft, setEditDraft] = React.useState(message.content);
-    const rootMessageId = message.branchRootId ?? message.id;
     const isProgressComplete = message.progress?.some(
       (item) => item.phase === "complete" && item.status === "completed",
     ) ?? false;
@@ -720,85 +721,6 @@ export const AgentTurn = React.memo(
           onMouseEnter={() => setIsHovered(true)}
           onMouseLeave={() => setIsHovered(false)}
         >
-          {isEditing ? (
-            <Paper
-              elevation={12}
-              sx={{
-                p: 1.5,
-                borderRadius: 5,
-                bgcolor: alpha("#ffffff", 0.75),
-                backdropFilter: "blur(40px)",
-                border: `1px solid ${alpha("#ffffff", 0.9)}`,
-                boxShadow: `0 16px 40px ${alpha("#000", 0.1)}, 0 0 0 1px ${alpha("#00acc1", 0.05)} inset`,
-                minWidth: { xs: 260, sm: 320, md: 400 },
-                maxWidth: "100%",
-              }}
-            >
-              <Box component="textarea"
-                autoFocus
-                value={editDraft}
-                onChange={(e) => setEditDraft(e.target.value)}
-                onKeyDown={(e) => {
-                  if (e.key === "Enter" && !e.shiftKey) {
-                    e.preventDefault();
-                    if (editDraft.trim() !== message.content) {
-                      onEditResubmit(message.id, editDraft);
-                    }
-                    setIsEditing(false);
-                  } else if (e.key === "Escape") {
-                    setEditDraft(message.content);
-                    setIsEditing(false);
-                  }
-                }}
-                sx={{
-                  width: "100%",
-                  minHeight: 60,
-                  bgcolor: "transparent",
-                  border: "none",
-                  outline: "none",
-                  resize: "none",
-                  fontFamily: "inherit",
-                  fontSize: "1rem",
-                  color: "text.primary",
-                  lineHeight: 1.6,
-                }}
-              />
-              <Stack direction="row" justifyContent="flex-end" spacing={1} sx={{ mt: 1 }}>
-                <IconButton 
-                  size="small" 
-                  aria-label="取消"
-                  onClick={() => { setEditDraft(message.content); setIsEditing(false); }}
-                  sx={{ 
-                    bgcolor: alpha("#000", 0.05), 
-                    color: "text.secondary",
-                    width: 34, height: 34,
-                    "&:hover": { bgcolor: alpha("#000", 0.1) }
-                  }}
-                >
-                  <CloseRounded fontSize="small" />
-                </IconButton>
-                <IconButton 
-                  size="small" 
-                  aria-label="发送修改"
-                  disabled={editDraft.trim() === "" || editDraft.trim() === message.content}
-                  onClick={() => {
-                    onEditResubmit(message.id, editDraft);
-                    setIsEditing(false);
-                  }}
-                  sx={{ 
-                    bgcolor: editDraft.trim() !== "" && editDraft.trim() !== message.content ? "#00acc1" : alpha("#000", 0.1), 
-                    color: editDraft.trim() !== "" && editDraft.trim() !== message.content ? "#fff" : "action.disabled",
-                    width: 34, height: 34,
-                    boxShadow: editDraft.trim() !== "" && editDraft.trim() !== message.content ? `0 4px 12px ${alpha("#00acc1", 0.4)}` : "none",
-                    "&:hover": { bgcolor: editDraft.trim() !== "" && editDraft.trim() !== message.content ? "#00838f" : alpha("#000", 0.1) }
-                  }}
-                >
-                  <SendRounded fontSize="small" sx={{ ml: 0.2 }} />
-                </IconButton>
-              </Stack>
-            </Paper>
-          ) : (
-            <>
           <Paper
             elevation={4}
             sx={{
@@ -825,80 +747,7 @@ export const AgentTurn = React.memo(
             }}
           >
             <MarkdownBlock>{message.content}</MarkdownBlock>
-                
-                <AnimatePresence>
-                  {isHovered && !isEditing && (
-                    <motion.div
-                      initial={{ opacity: 0, scale: 0.9 }}
-                      animate={{ opacity: 1, scale: 1 }}
-                      exit={{ opacity: 0, scale: 0.9 }}
-                      transition={{ duration: 0.15 }}
-                      style={{ position: "absolute", top: -12, right: -8, zIndex: 10 }}
-                    >
-                      <IconButton
-                        size="small"
-                        onClick={() => { setIsEditing(true); setEditDraft(message.content); }}
-                        aria-label="编辑提问"
-                        sx={{
-                          width: 26,
-                          height: 26,
-                          bgcolor: alpha("#fff", 0.9),
-                          color: "#00acc1",
-                          boxShadow: `0 2px 8px ${alpha("#000", 0.15)}`,
-                          "&:hover": { bgcolor: "#fff", color: "#00838f" }
-                        }}
-                      >
-                        <EditRounded sx={{ fontSize: 14 }} />
-                      </IconButton>
-                    </motion.div>
-                  )}
-                </AnimatePresence>
           </Paper>
-
-              {branchState && branchState.total > 1 ? (
-                <Stack
-                  direction="row"
-                  justifyContent="flex-end"
-                  sx={{ mt: 0.5, mr: 0.5 }}
-                >
-                  <Paper
-                    elevation={0}
-                    sx={{
-                      display: "flex",
-                      alignItems: "center",
-                      gap: 0.5,
-                      px: 0.5,
-                      py: 0.25,
-                      borderRadius: 4,
-                      bgcolor: alpha("#000", 0.04),
-                      backdropFilter: "blur(4px)",
-                      border: `1px solid ${alpha("#000", 0.08)}`,
-                    }}
-                  >
-                    <IconButton
-                      size="small"
-                      aria-label="上一分支"
-                      onClick={() => onCycleBranch(rootMessageId, -1)}
-                      sx={{ width: 22, height: 22, color: "text.secondary", "&:hover": { bgcolor: alpha("#000", 0.08) } }}
-                    >
-                      <ChevronLeftRounded sx={{ fontSize: 16 }} />
-                    </IconButton>
-                    <Typography variant="caption" sx={{ color: "text.secondary", fontWeight: 600, fontSize: "0.7rem", px: 0.5, userSelect: "none" }}>
-                      {branchState.activeIndex + 1} / {branchState.total}
-                    </Typography>
-                    <IconButton
-                      size="small"
-                      aria-label="下一分支"
-                      onClick={() => onCycleBranch(rootMessageId, 1)}
-                      sx={{ width: 22, height: 22, color: "text.secondary", "&:hover": { bgcolor: alpha("#000", 0.08) } }}
-                    >
-                      <ChevronRightRounded sx={{ fontSize: 16 }} />
-                    </IconButton>
-                  </Paper>
-                </Stack>
-              ) : null}
-            </>
-          )}
         </motion.div>
       );
     }
@@ -1060,7 +909,9 @@ export const AgentTurn = React.memo(
                         size="small" 
                         aria-label="复制" 
                         onClick={() => {
-                          navigator.clipboard.writeText(message.content);
+                          navigator.clipboard.writeText(
+                            normalizeClipboardText(message.content),
+                          );
                           // Could add a toast here
                         }}
                         sx={{ width: 28, height: 28, color: "text.secondary", "&:hover": { color: "#00acc1", bgcolor: alpha("#00acc1", 0.1) } }}
@@ -1073,13 +924,25 @@ export const AgentTurn = React.memo(
                         size="small" 
                         aria-label="重新生成" 
                         onClick={() => {
-                          onRegenerate();
+                          onRegenerate(message.id);
                         }}
                         sx={{ width: 28, height: 28, color: "text.secondary", "&:hover": { color: "#00acc1", bgcolor: alpha("#00acc1", 0.1) } }}
                       >
                         <RefreshRounded sx={{ fontSize: 16 }} />
                       </IconButton>
                     </Tooltip>
+                    <Tooltip title="拆分为新会话">
+                      <IconButton
+                        size="small"
+                        aria-label="拆分为新会话"
+                        onClick={() => {
+                          onCreateBranch(message.id);
+                        }}
+                        sx={{ width: 28, height: 28, color: "text.secondary", "&:hover": { color: "#00acc1", bgcolor: alpha("#00acc1", 0.1) } }}
+                      >
+                        <TbArrowsSplit2 size={16} />
+                      </IconButton>
+                    </Tooltip>
                   </Paper>
                 </motion.div>
               )}
@@ -1088,11 +951,9 @@ export const AgentTurn = React.memo(
           </Paper>
         </Stack>
 
-        {(!isErrorMessage && isTtsSupported) || (branchState && branchState.total > 1) ? (
+        {!isErrorMessage && isTtsSupported ? (
           <Stack direction="row" alignItems="center" justifyContent="space-between" sx={{ mt: 0.5, ml: 6, mb: 1 }}>
             <Stack direction="row" spacing={0.5} sx={{ opacity: isHovered ? 1 : 0.4, transition: "opacity 0.2s" }}>
-              {!isErrorMessage && isTtsSupported ? (
-                <>
               {messageSpeechState === "idle" ? (
                 <IconButton
                   size="small"
@@ -1123,52 +984,7 @@ export const AgentTurn = React.memo(
                   </IconButton>
                 </>
               ) : null}
-                </>
-              ) : null}
             </Stack>
-
-            {branchState && branchState.total > 1 ? (
-              <Stack
-                direction="row"
-                justifyContent="flex-start"
-                sx={{ mr: 0.5 }}
-              >
-                <Paper
-                  elevation={0}
-                  sx={{
-                    display: "flex",
-                    alignItems: "center",
-                    gap: 0.5,
-                    px: 0.5,
-                    py: 0.25,
-                    borderRadius: 4,
-                    bgcolor: alpha("#000", 0.04),
-                    backdropFilter: "blur(4px)",
-                    border: `1px solid ${alpha("#000", 0.08)}`,
-                  }}
-                >
-                  <IconButton
-                    size="small"
-                    aria-label="上一分支"
-                    onClick={() => onCycleBranch(rootMessageId, -1)}
-                    sx={{ width: 22, height: 22, color: "text.secondary", "&:hover": { bgcolor: alpha("#000", 0.08) } }}
-                  >
-                    <ChevronLeftRounded sx={{ fontSize: 16 }} />
-                  </IconButton>
-                  <Typography variant="caption" sx={{ color: "text.secondary", fontWeight: 600, fontSize: "0.7rem", px: 0.5, userSelect: "none" }}>
-                    {branchState.activeIndex + 1} / {branchState.total}
-                  </Typography>
-                  <IconButton
-                    size="small"
-                    aria-label="下一分支"
-                    onClick={() => onCycleBranch(rootMessageId, 1)}
-                    sx={{ width: 22, height: 22, color: "text.secondary", "&:hover": { bgcolor: alpha("#000", 0.08) } }}
-                  >
-                    <ChevronRightRounded sx={{ fontSize: 16 }} />
-                  </IconButton>
-                </Paper>
-              </Stack>
-            ) : null}
           </Stack>
         ) : null}
       </motion.div>

src/components/chat/AgentWorkspace.test.tsx

@@ -33,8 +33,6 @@ jest.mock("./AgentTurn", () => ({
 
 describe("AgentWorkspace", () => {
   const defaultProps = {
-    branchGroups: [],
-    branchTransition: null,
     bottomRef: { current: null },
     speakingMessageId: null,
     speechState: "idle" as const,
@@ -44,8 +42,7 @@ describe("AgentWorkspace", () => {
     onStopSpeech: jest.fn(),
     isTtsSupported: false,
     onRegenerate: jest.fn(),
-    onEditResubmit: jest.fn(),
+    onCreateBranch: jest.fn(),
-    onCycleBranch: jest.fn(),
     onReplyPermission: jest.fn(),
   };
 

src/components/chat/AgentWorkspace.tsx

@@ -13,17 +13,12 @@ import { AgentTurn } from "./AgentTurn";
 import { TypingIndicator } from "./GlobalChatbox.parts";
 import type { PermissionReply } from "@/lib/chatStream";
 import type {
-  BranchGroup,
-  BranchState,
-  BranchTransition,
   Message,
   SpeechState,
 } from "./GlobalChatbox.types";
 
 type AgentWorkspaceProps = {
   messages: Message[];
-  branchGroups: BranchGroup[];
-  branchTransition: BranchTransition | null;
   isStreaming: boolean;
   bottomRef: React.RefObject<HTMLDivElement | null>;
   speakingMessageId: string | null;
@@ -33,15 +28,13 @@ type AgentWorkspaceProps = {
   onResumeSpeech: () => void;
   onStopSpeech: () => void;
   isTtsSupported: boolean;
-  onRegenerate: () => void;
+  onRegenerate: (messageId: string) => void;
-  onEditResubmit: (messageId: string, newContent: string) => void;
+  onCreateBranch: (messageId: string) => void;
-  onCycleBranch: (rootMessageId: string, direction: -1 | 1) => void;
   onReplyPermission: (requestId: string, reply: PermissionReply) => void;
 };
 
 type TurnListProps = {
   messages: Message[];
-  branchGroups: BranchGroup[];
   speakingMessageId: string | null;
   speechState: SpeechState;
   onSpeak: (messageId: string, text: string) => void;
@@ -49,9 +42,8 @@ type TurnListProps = {
   onResumeSpeech: () => void;
   onStopSpeech: () => void;
   isTtsSupported: boolean;
-  onRegenerate: () => void;
+  onRegenerate: (messageId: string) => void;
-  onEditResubmit: (messageId: string, newContent: string) => void;
+  onCreateBranch: (messageId: string) => void;
-  onCycleBranch: (rootMessageId: string, direction: -1 | 1) => void;
   onReplyPermission: (requestId: string, reply: PermissionReply) => void;
 };
 
@@ -61,7 +53,6 @@ const sameMessages = (left: Message[], right: Message[]) =>
 
 const TurnListInner = ({
   messages,
-  branchGroups,
   speakingMessageId,
   speechState,
   onSpeak,
@@ -70,32 +61,15 @@ const TurnListInner = ({
   onStopSpeech,
   isTtsSupported,
   onRegenerate,
-  onEditResubmit,
+  onCreateBranch,
-  onCycleBranch,
   onReplyPermission,
 }: TurnListProps) => {
-  const branchStateByRootId = React.useMemo(() => {
-    const next = new Map<string, BranchState>();
-    branchGroups.forEach((group) => {
-      if (group.branches.length > 1) {
-        next.set(group.rootMessageId, {
-          activeIndex: group.activeIndex,
-          total: group.branches.length,
-        });
-      }
-    });
-    return next;
-  }, [branchGroups]);
-
   return (
     <>
-      {messages.map((message) => {
+      {messages.map((message) => (
-        const rootMessageId = message.branchRootId ?? message.id;
-        return (
         <AgentTurn
-            key={rootMessageId}
+          key={message.id}
           message={message}
-            branchState={branchStateByRootId.get(rootMessageId)}
           messageSpeechState={speakingMessageId === message.id ? speechState : "idle"}
           onSpeak={onSpeak}
           onPause={onPauseSpeech}
@@ -103,12 +77,10 @@ const TurnListInner = ({
           onStopSpeech={onStopSpeech}
           isTtsSupported={isTtsSupported}
           onRegenerate={onRegenerate}
-            onEditResubmit={onEditResubmit}
+          onCreateBranch={onCreateBranch}
-            onCycleBranch={onCycleBranch}
           onReplyPermission={onReplyPermission}
         />
-        );
+      ))}
-      })}
     </>
   );
 };
@@ -117,7 +89,6 @@ const TurnList = React.memo(
   TurnListInner,
   (prevProps, nextProps) =>
     sameMessages(prevProps.messages, nextProps.messages) &&
-    prevProps.branchGroups === nextProps.branchGroups &&
     prevProps.speakingMessageId === nextProps.speakingMessageId &&
     prevProps.speechState === nextProps.speechState &&
     prevProps.onSpeak === nextProps.onSpeak &&
@@ -126,8 +97,7 @@ const TurnList = React.memo(
     prevProps.onStopSpeech === nextProps.onStopSpeech &&
     prevProps.isTtsSupported === nextProps.isTtsSupported &&
     prevProps.onRegenerate === nextProps.onRegenerate &&
-    prevProps.onEditResubmit === nextProps.onEditResubmit &&
+    prevProps.onCreateBranch === nextProps.onCreateBranch &&
-    prevProps.onCycleBranch === nextProps.onCycleBranch &&
     prevProps.onReplyPermission === nextProps.onReplyPermission,
 );
 
@@ -249,8 +219,6 @@ const EmptyState = () => {
 
 export const AgentWorkspace = ({
   messages,
-  branchGroups,
-  branchTransition,
   isStreaming,
   bottomRef,
   speakingMessageId,
@@ -261,8 +229,7 @@ export const AgentWorkspace = ({
   onStopSpeech,
   isTtsSupported,
   onRegenerate,
-  onEditResubmit,
+  onCreateBranch,
-  onCycleBranch,
   onReplyPermission,
 }: AgentWorkspaceProps) => {
   const theme = useTheme();
@@ -274,18 +241,12 @@ export const AgentWorkspace = ({
     (!latestAssistant ||
       (latestAssistant.content.trim().length === 0 &&
         !(latestAssistant.artifacts?.length)));
-  const stableMessages = branchTransition
-    ? messages.slice(0, branchTransition.parentCount)
-    : messages;
-  const transitionMessages = branchTransition
-    ? messages.slice(branchTransition.parentCount)
-    : [];
   const streamingMessage =
-    !branchTransition && isStreaming && messages.at(-1)?.role === "assistant"
+    isStreaming && messages.at(-1)?.role === "assistant"
       ? messages.at(-1)
       : undefined;
   const historyMessages =
-    streamingMessage !== undefined ? messages.slice(0, -1) : stableMessages;
+    streamingMessage !== undefined ? messages.slice(0, -1) : messages;
 
   return (
     <Box
@@ -307,7 +268,6 @@ export const AgentWorkspace = ({
         <Box sx={{ display: "flex", flexDirection: "column", gap: 2 }}>
           <TurnList
             messages={historyMessages}
-            branchGroups={branchGroups}
             speakingMessageId={speakingMessageId}
             speechState={speechState}
             onSpeak={onSpeak}
@@ -316,15 +276,13 @@ export const AgentWorkspace = ({
             onStopSpeech={onStopSpeech}
             isTtsSupported={isTtsSupported}
             onRegenerate={onRegenerate}
-            onEditResubmit={onEditResubmit}
+            onCreateBranch={onCreateBranch}
-            onCycleBranch={onCycleBranch}
             onReplyPermission={onReplyPermission}
           />
 
           {streamingMessage ? (
             <TurnList
               messages={[streamingMessage]}
-              branchGroups={branchGroups}
               speakingMessageId={speakingMessageId}
               speechState={speechState}
               onSpeak={onSpeak}
@@ -333,40 +291,10 @@ export const AgentWorkspace = ({
               onStopSpeech={onStopSpeech}
               isTtsSupported={isTtsSupported}
               onRegenerate={onRegenerate}
-              onEditResubmit={onEditResubmit}
+              onCreateBranch={onCreateBranch}
-              onCycleBranch={onCycleBranch}
               onReplyPermission={onReplyPermission}
             />
           ) : null}
-
-          {branchTransition ? (
-            <AnimatePresence initial={false} mode="wait">
-              <motion.div
-                key={`${branchTransition.rootMessageId}:${branchTransition.activeBranchId}:${branchTransition.nonce}`}
-                initial={{ opacity: 0, y: 8 }}
-                animate={{ opacity: 1, y: 0 }}
-                exit={{ opacity: 0, y: -8 }}
-                transition={{ duration: 0.18, ease: "easeOut" }}
-                style={{ display: "flex", flexDirection: "column", gap: 16 }}
-              >
-                <TurnList
-                  messages={transitionMessages}
-                  branchGroups={branchGroups}
-                  speakingMessageId={speakingMessageId}
-                  speechState={speechState}
-                  onSpeak={onSpeak}
-                  onPauseSpeech={onPauseSpeech}
-                  onResumeSpeech={onResumeSpeech}
-                  onStopSpeech={onStopSpeech}
-                  isTtsSupported={isTtsSupported}
-                  onRegenerate={onRegenerate}
-                  onEditResubmit={onEditResubmit}
-                  onCycleBranch={onCycleBranch}
-                  onReplyPermission={onReplyPermission}
-                />
-              </motion.div>
-            </AnimatePresence>
-          ) : null}
         </Box>
       ) : null}
 

src/components/chat/GlobalChatbox.tsx

@@ -67,15 +67,12 @@ export const GlobalChatbox: React.FC<Props> = ({ open, onClose }) => {
     messages,
     chatSessions,
     activeSessionId,
-    branchGroups,
-    branchTransition,
     isHydrating,
     isStreaming,
     sessionTitle,
     sendPrompt,
     regenerate,
-    editAndResubmit,
+    createBranch,
-    cycleBranch,
     abort,
     replyPermission,
     createSession,
@@ -344,8 +341,6 @@ export const GlobalChatbox: React.FC<Props> = ({ open, onClose }) => {
           <Box sx={{ flex: 1, display: "flex", minWidth: 0, flexDirection: "column" }}>
             <AgentWorkspace
               messages={messages}
-              branchGroups={branchGroups}
-              branchTransition={branchTransition}
               isStreaming={isStreaming}
               bottomRef={bottomRef}
               speakingMessageId={speakingMessageId}
@@ -356,8 +351,7 @@ export const GlobalChatbox: React.FC<Props> = ({ open, onClose }) => {
               onStopSpeech={handleStopSpeech}
               isTtsSupported={isTtsSupported}
               onRegenerate={regenerate}
-              onEditResubmit={editAndResubmit}
+              onCreateBranch={createBranch}
-              onCycleBranch={cycleBranch}
               onReplyPermission={replyPermission}
             />
 

src/components/chat/GlobalChatbox.types.ts

@@ -55,34 +55,6 @@ export type Message = {
   progress?: ChatProgress[];
   artifacts?: AgentArtifact[];
   permissions?: AgentPermissionRequest[];
-  branchRootId?: string;
-};
-
-export type BranchState = {
-  activeIndex: number;
-  total: number;
-};
-
-export type MessageBranch = {
-  id: string;
-  label: string;
-  sessionId?: string;
-  messages: Message[];
-};
-
-export type BranchGroup = {
-  id: string;
-  rootMessageId: string;
-  parentCount: number;
-  activeIndex: number;
-  branches: MessageBranch[];
-};
-
-export type BranchTransition = {
-  rootMessageId: string;
-  parentCount: number;
-  activeBranchId: string;
-  nonce: number;
 };
 
 export type Props = {
@@ -106,7 +78,6 @@ export type LoadedChatState = {
   title?: string;
   isTitleManuallyEdited?: boolean;
   messages: Message[];
-  branchGroups: BranchGroup[];
   isStreaming?: boolean;
   runStatus?: string;
 };

src/components/chat/GlobalChatbox.utils.ts

@@ -1,4 +1,4 @@
-import type { BranchGroup, Message } from "./GlobalChatbox.types";
+import type { Message } from "./GlobalChatbox.types";
 
 export const createId = () =>
   `${Date.now()}-${Math.random().toString(36).slice(2, 8)}`;
@@ -36,12 +36,3 @@ export const cloneMessage = (message: Message): Message => ({
 });
 
 export const cloneMessages = (messages: Message[]) => messages.map(cloneMessage);
-
-export const cloneBranchGroups = (branchGroups: BranchGroup[]) =>
-  branchGroups.map((group) => ({
-    ...group,
-    branches: group.branches.map((branch) => ({
-      ...branch,
-      messages: cloneMessages(branch.messages),
-    })),
-  }));

src/components/chat/chatStorage.test.ts

@@ -21,7 +21,6 @@ describe("chatStorage backend-only persistence", () => {
       title: undefined,
       messages: [],
       sessionId: undefined,
-      branchGroups: [],
     });
     expect(apiFetch).not.toHaveBeenCalled();
   });
@@ -60,11 +59,9 @@ describe("chatStorage backend-only persistence", () => {
             id: "message-2",
             role: "user",
             content: "第一条消息",
-            branchRootId: "message-2",
           },
         ],
         sessionId: undefined,
-        branchGroups: [],
       },
     );
 

src/components/chat/chatStorage.ts

@@ -2,12 +2,11 @@ import { apiFetch } from "@/lib/apiFetch";
 import { config } from "@config/config";
 
 import type {
-  BranchGroup,
   ChatSessionSummary,
   LoadedChatState,
   Message,
 } from "./GlobalChatbox.types";
-import { cloneBranchGroups, cloneMessages } from "./GlobalChatbox.utils";
+import { cloneMessages } from "./GlobalChatbox.utils";
 
 type BackendSessionPayload = {
   id?: string;
@@ -23,22 +22,16 @@ export const createEmptyChatState = (): LoadedChatState => ({
   isTitleManuallyEdited: false,
   messages: [],
   sessionId: undefined,
-  branchGroups: [],
 });
 
 const sanitizeMessages = (messages: Message[] | undefined) =>
   Array.isArray(messages) ? cloneMessages(messages) : [];
 
-const sanitizeBranchGroups = (branchGroups: BranchGroup[] | undefined) =>
-  Array.isArray(branchGroups) ? cloneBranchGroups(branchGroups) : [];
-
 const hasChatContent = (state: {
   messages: Message[];
-  branchGroups: BranchGroup[];
   sessionId?: string;
 }) =>
   state.messages.length > 0 ||
-  state.branchGroups.length > 0 ||
   Boolean(state.sessionId);
 
 const compareSessionsByAnchorTime = (
@@ -107,7 +100,6 @@ const fetchBackendChatSession = async (sessionId: string): Promise<LoadedChatSta
     is_title_manually_edited?: boolean;
     session_id?: string;
     messages?: Message[];
-    branch_groups?: BranchGroup[];
     is_streaming?: boolean;
     run_status?: string;
   };
@@ -116,7 +108,6 @@ const fetchBackendChatSession = async (sessionId: string): Promise<LoadedChatSta
     isTitleManuallyEdited: payload.is_title_manually_edited ?? false,
     messages: sanitizeMessages(payload.messages),
     sessionId: payload.session_id ?? payload.id,
-    branchGroups: sanitizeBranchGroups(payload.branch_groups),
     isStreaming: payload.is_streaming ?? false,
     runStatus: payload.run_status,
   };
@@ -167,7 +158,6 @@ const saveBackendChatState = async (
         title: normalizeTitle(state.title),
         is_title_manually_edited: state.isTitleManuallyEdited ?? false,
         messages: sanitizeMessages(state.messages),
-        branch_groups: sanitizeBranchGroups(state.branchGroups),
       }),
       projectHeaderMode: "include",
       userHeaderMode: "include",

src/components/chat/hooks/useAgentChatSession.test.tsx

@@ -5,6 +5,7 @@ import { act, renderHook, waitFor } from "@testing-library/react";
 import { useAgentChatSession } from "./useAgentChatSession";
 import {
   abortAgentChat,
+  forkAgentChat,
   replyAgentPermission,
   resumeAgentChatStream,
   streamAgentChat,
@@ -30,7 +31,6 @@ jest.mock("../chatStorage", () => ({
     isTitleManuallyEdited: false,
     messages: [],
     sessionId: undefined,
-    branchGroups: [],
   })),
   deleteChatSession: (...args: unknown[]) => deleteChatSession(...args),
   listChatSessions: (...args: unknown[]) => listChatSessions(...args),
@@ -39,7 +39,6 @@ jest.mock("../chatStorage", () => ({
     isTitleManuallyEdited: false,
     messages: [],
     sessionId: "session-loaded",
-    branchGroups: [],
   })),
   saveActiveChatState: (...args: unknown[]) => saveActiveChatState(...args),
   updateChatSessionTitle: (...args: unknown[]) => updateChatSessionTitle(...args),
@@ -52,10 +51,12 @@ describe("useAgentChatSession", () => {
     saveActiveChatState.mockReset();
     updateChatSessionTitle.mockReset();
     jest.mocked(abortAgentChat).mockReset();
+    jest.mocked(forkAgentChat).mockReset();
     jest.mocked(replyAgentPermission).mockReset();
     jest.mocked(resumeAgentChatStream).mockReset();
     jest.mocked(streamAgentChat).mockReset();
     jest.mocked(abortAgentChat).mockImplementation(async () => undefined);
+    jest.mocked(forkAgentChat).mockImplementation(async () => "forked-session");
     jest.mocked(replyAgentPermission).mockImplementation(async () => undefined);
     jest.mocked(resumeAgentChatStream).mockImplementation(async () => undefined);
     jest.mocked(streamAgentChat).mockImplementation(async () => undefined);
@@ -596,9 +597,10 @@ describe("useAgentChatSession", () => {
     await act(async () => {
       await result.current.sendPrompt("重新分析压力异常");
     });
+    const assistantMessageId = result.current.messages[1]?.id ?? "";
 
     await act(async () => {
-      await result.current.regenerate();
+      await result.current.regenerate(assistantMessageId);
     });
 
     expect(streamAgentChat).toHaveBeenNthCalledWith(
@@ -609,4 +611,91 @@ describe("useAgentChatSession", () => {
       }),
     );
   });
+
+  it("replaces the current chain when regenerating a middle assistant message", async () => {
+    listChatSessions.mockResolvedValue([]);
+
+    const { result } = renderHook(() =>
+      useAgentChatSession({
+        projectId: "project-1",
+        onToolCall: jest.fn(),
+      }),
+    );
+
+    await waitFor(() => expect(result.current.isHydrating).toBe(false));
+
+    await act(async () => {
+      await result.current.sendPrompt("第一轮");
+    });
+
+    await act(async () => {
+      await result.current.sendPrompt("第二轮");
+    });
+
+    const firstAssistantMessageId = result.current.messages[1]?.id ?? "";
+
+    await act(async () => {
+      await result.current.regenerate(firstAssistantMessageId);
+    });
+
+    expect(result.current.messages).toHaveLength(2);
+    expect(result.current.messages[0]).toEqual(
+      expect.objectContaining({
+        role: "user",
+        content: "第一轮",
+      }),
+    );
+    expect(result.current.messages[1]).toEqual(
+      expect.objectContaining({
+        role: "assistant",
+        content: "",
+      }),
+    );
+    expect(streamAgentChat).toHaveBeenNthCalledWith(
+      3,
+      expect.objectContaining({
+        message: "第一轮",
+        regenerateFromMessageIndex: 0,
+      }),
+    );
+  });
+
+  it("forks a copied conversation from an assistant message", async () => {
+    listChatSessions.mockResolvedValue([]);
+
+    const { result } = renderHook(() =>
+      useAgentChatSession({
+        projectId: "project-1",
+        onToolCall: jest.fn(),
+      }),
+    );
+
+    await waitFor(() => expect(result.current.isHydrating).toBe(false));
+
+    await act(async () => {
+      await result.current.sendPrompt("第一轮");
+    });
+
+    const firstAssistantMessageId = result.current.messages[1]?.id ?? "";
+
+    await act(async () => {
+      await result.current.createBranch(firstAssistantMessageId);
+    });
+
+    expect(forkAgentChat).toHaveBeenCalledWith(undefined, 2);
+    expect(result.current.activeSessionId).toBe("forked-session");
+    expect(result.current.messages).toHaveLength(2);
+    expect(result.current.messages[0]).toEqual(
+      expect.objectContaining({
+        role: "user",
+        content: "第一轮",
+      }),
+    );
+    expect(result.current.messages[1]).toEqual(
+      expect.objectContaining({
+        role: "assistant",
+      }),
+    );
+    expect(streamAgentChat).toHaveBeenCalledTimes(1);
+  });
 });

src/components/chat/hooks/useAgentChatSession.ts

@@ -18,15 +18,12 @@ import type {
 import type {
   AgentArtifact,
   AgentPermissionRequest,
-  BranchGroup,
-  BranchTransition,
   ChatProgress,
   ChatSessionSummary,
   LoadedChatState,
   Message,
 } from "../GlobalChatbox.types";
 import {
-  cloneBranchGroups,
   cloneMessages,
   createId,
 } from "../GlobalChatbox.utils";
@@ -68,7 +65,6 @@ const createPersistedStateKey = (state: LoadedChatState) =>
     isTitleManuallyEdited: state.isTitleManuallyEdited ?? false,
     sessionId: state.sessionId ?? null,
     messages: state.messages,
-    branchGroups: state.branchGroups,
   });
 
 const upsertProgress = (
@@ -193,13 +189,12 @@ const finalizeAssistantMessageAfterAbort = (message: Message): Message => {
   };
 };
 
-const createUserMessage = (content: string, branchRootId?: string): Message => {
+const createUserMessage = (content: string): Message => {
   const id = createId();
   return {
     id,
     role: "user",
     content,
-    branchRootId: branchRootId ?? id,
   };
 };
 
@@ -209,9 +204,6 @@ const createAssistantMessage = (): Message => ({
   content: "",
 });
 
-const messagesEqual = (left: Message[], right: Message[]) =>
-  JSON.stringify(left) === JSON.stringify(right);
-
 export const useAgentChatSession = ({
   projectId,
   onToolCall,
@@ -226,15 +218,12 @@ export const useAgentChatSession = ({
   const [sessionTitle, setSessionTitle] = useState<string | undefined>(undefined);
   const [isSessionTitleManuallyEdited, setIsSessionTitleManuallyEdited] = useState(false);
   const [sessionId, setSessionId] = useState<string | undefined>(undefined);
-  const [branchGroups, setBranchGroups] = useState<BranchGroup[]>([]);
   const [chatSessions, setChatSessions] = useState<ChatSessionSummary[]>([]);
-  const [branchTransition, setBranchTransition] = useState<BranchTransition | null>(null);
   const [isStreaming, setIsStreaming] = useState(false);
   const [isHydrating, setIsHydrating] = useState(true);
   const abortRef = useRef<AbortController | null>(null);
   const sessionIdRef = useRef<string | undefined>(undefined);
   const messagesRef = useRef<Message[]>([]);
-  const branchGroupsRef = useRef<BranchGroup[]>([]);
   const resumeStreamingSessionRef = useRef<((sessionId: string) => void) | null>(null);
   const isSessionTitleManuallyEditedRef = useRef(false);
   const cancelPromiseRef = useRef<Promise<void> | null>(null);
@@ -245,7 +234,6 @@ export const useAgentChatSession = ({
       title: undefined,
       isTitleManuallyEdited: false,
       messages: [],
-      branchGroups: [],
     }),
   );
 
@@ -257,9 +245,6 @@ export const useAgentChatSession = ({
     messagesRef.current = messages;
   }, [messages]);
 
-  useEffect(() => {
-    branchGroupsRef.current = branchGroups;
-  }, [branchGroups]);
 
   useEffect(() => {
     isSessionTitleManuallyEditedRef.current = isSessionTitleManuallyEdited;
@@ -279,17 +264,14 @@ export const useAgentChatSession = ({
           isTitleManuallyEdited: false,
           messages: [],
           sessionId: undefined,
-          branchGroups: [],
         });
         hydrationCompletedRef.current = true;
         hydrationNonceRef.current += 1;
         titleUpdateNonceRef.current += 1;
-        setBranchTransition(null);
         setMessages([]);
         setSessionTitle(undefined);
         setIsSessionTitleManuallyEdited(false);
         setSessionId(undefined);
-        setBranchGroups([]);
         setChatSessions([]);
         setIsHydrating(false);
         return;
@@ -313,7 +295,6 @@ export const useAgentChatSession = ({
         setSessionTitle(loadedState.title);
         setIsSessionTitleManuallyEdited(loadedState.isTitleManuallyEdited ?? false);
         setSessionId(loadedState.sessionId);
-        setBranchGroups(loadedState.branchGroups);
         setChatSessions(sessions);
         if (
           loadedState.sessionId &&
@@ -351,7 +332,6 @@ export const useAgentChatSession = ({
         isTitleManuallyEdited: isSessionTitleManuallyEdited,
         messages,
         sessionId,
-        branchGroups,
       };
 
       const currentStateKey = createPersistedStateKey(state);
@@ -381,46 +361,7 @@ export const useAgentChatSession = ({
     return () => {
       window.clearTimeout(persistTimer);
     };
-  }, [branchGroups, isHydrating, isSessionTitleManuallyEdited, isStreaming, messages, projectId, sessionId, sessionTitle]);
+  }, [isHydrating, isSessionTitleManuallyEdited, isStreaming, messages, projectId, sessionId, sessionTitle]);
-
-  useEffect(() => {
-    setBranchGroups((prev) => {
-      let changed = false;
-      const next = prev.map((group) => {
-        const rootMessage = messages[group.parentCount];
-        if (
-          !rootMessage ||
-          rootMessage.role !== "user" ||
-          (rootMessage.branchRootId ?? rootMessage.id) !== group.rootMessageId
-        ) {
-          return group;
-        }
-
-        const activeBranch = group.branches[group.activeIndex];
-        if (!activeBranch) {
-          return group;
-        }
-
-        const nextSuffix = cloneMessages(messages.slice(group.parentCount));
-        if (
-          activeBranch.sessionId === sessionId &&
-          messagesEqual(activeBranch.messages, nextSuffix)
-        ) {
-          return group;
-        }
-
-        changed = true;
-        const branches = group.branches.map((branch, index) =>
-          index === group.activeIndex
-            ? { ...branch, sessionId, messages: nextSuffix }
-            : branch,
-        );
-        return { ...group, branches };
-      });
-
-      return changed ? next : prev;
-    });
-  }, [messages, sessionId]);
 
   const appendArtifact = useCallback((messageId: string, artifact: AgentArtifact) => {
     setMessages((prev) =>
@@ -479,7 +420,6 @@ export const useAgentChatSession = ({
               title: nextTitle,
               isTitleManuallyEdited: false,
               messages: messagesRef.current,
-              branchGroups: branchGroupsRef.current,
             });
           }
           if (targetSessionId) {
@@ -643,7 +583,6 @@ export const useAgentChatSession = ({
 
       await cancelPromiseRef.current?.catch(() => undefined);
       onBeforeSend?.();
-      setBranchTransition(null);
 
       const nextUserMessage = userMessage ?? createUserMessage(prompt);
       const nextAssistantMessage = assistantMessage ?? createAssistantMessage();
@@ -832,7 +771,6 @@ export const useAgentChatSession = ({
 
     const controller = abortRef.current;
     controller?.abort();
-    setBranchTransition(null);
     hydrationNonceRef.current += 1;
     titleUpdateNonceRef.current += 1;
     sessionIdRef.current = undefined;
@@ -841,13 +779,11 @@ export const useAgentChatSession = ({
       isTitleManuallyEdited: false,
       messages: [],
       sessionId: undefined,
-      branchGroups: [],
     });
     setMessages([]);
     setSessionTitle("新对话");
     setIsSessionTitleManuallyEdited(false);
     setSessionId(undefined);
-    setBranchGroups([]);
     setIsStreaming(false);
   }, [isHydrating, isStreaming]);
 
@@ -868,12 +804,10 @@ export const useAgentChatSession = ({
         titleUpdateNonceRef.current += 1;
         sessionIdRef.current = nextState.sessionId;
         lastPersistedStateKeyRef.current = createPersistedStateKey(nextState);
-        setBranchTransition(null);
         setMessages(nextState.messages);
         setSessionTitle(nextState.title);
         setIsSessionTitleManuallyEdited(nextState.isTitleManuallyEdited ?? false);
         setSessionId(nextState.sessionId);
-        setBranchGroups(nextState.branchGroups);
         setChatSessions(sessions);
         if (nextState.sessionId && nextState.isStreaming) {
           resumeStreamingSession(nextState.sessionId);
@@ -917,14 +851,11 @@ export const useAgentChatSession = ({
             isTitleManuallyEdited: false,
             messages: [],
             sessionId: undefined,
-            branchGroups: [],
           });
-          setBranchTransition(null);
           setMessages([]);
           setSessionTitle(undefined);
           setIsSessionTitleManuallyEdited(false);
           setSessionId(undefined);
-          setBranchGroups([]);
           return;
         }
 
@@ -937,12 +868,10 @@ export const useAgentChatSession = ({
         titleUpdateNonceRef.current += 1;
         sessionIdRef.current = nextState.sessionId;
         lastPersistedStateKeyRef.current = createPersistedStateKey(nextState);
-        setBranchTransition(null);
         setMessages(nextState.messages);
         setSessionTitle(nextState.title);
         setIsSessionTitleManuallyEdited(nextState.isTitleManuallyEdited ?? false);
         setSessionId(nextState.sessionId);
-        setBranchGroups(nextState.branchGroups);
         setChatSessions(sessionsAfterDelete);
       } catch (error) {
         console.error("[GlobalChatbox] Failed to delete chat session:", error);
@@ -985,39 +914,42 @@ export const useAgentChatSession = ({
             title: normalizedTitle,
             isTitleManuallyEdited: true,
             messages,
-            branchGroups,
           });
         }
       } catch (error) {
         console.error("[GlobalChatbox] Failed to rename chat session:", error);
       }
     },
-    [branchGroups, isHydrating, messages],
+    [isHydrating, messages],
   );
 
-  const regenerate = useCallback(async () => {
+  const regenerate = useCallback(async (messageId: string) => {
     if (isHydrating || isStreaming || messages.length === 0) return;
 
-    let lastUserIndex = messages.length - 1;
+    const targetAssistantIndex = messages.findIndex(
-    while (lastUserIndex >= 0 && messages[lastUserIndex].role !== "user") {
+      (message) => message.id === messageId && message.role === "assistant",
-      lastUserIndex--;
+    );
+    if (targetAssistantIndex < 0) {
+      return;
     }
 
-    if (lastUserIndex < 0) return;
+    let targetUserIndex = targetAssistantIndex - 1;
+    while (targetUserIndex >= 0 && messages[targetUserIndex].role !== "user") {
+      targetUserIndex--;
+    }
 
-      const lastUser = messages[lastUserIndex];
+    if (targetUserIndex < 0) return;
-      const lastUserContent = lastUser.content;
+
-      const nextMessages = cloneMessages(messages.slice(0, lastUserIndex));
+    const targetUser = messages[targetUserIndex];
-      const nextUserMessage = createUserMessage(
+    const targetUserContent = targetUser.content;
-        lastUserContent,
+    const nextMessages = cloneMessages(messages.slice(0, targetUserIndex));
-        lastUser.branchRootId ?? lastUser.id,
+    const nextUserMessage = createUserMessage(targetUserContent);
-      );
     const nextAssistantMessage = createAssistantMessage();
 
     setMessages(nextMessages);
     await runPrompt({
-        prompt: lastUserContent,
+      prompt: targetUserContent,
-        regenerateFromMessageIndex: lastUserIndex,
+      regenerateFromMessageIndex: targetUserIndex,
       preparedMessages: [
         ...nextMessages,
         nextUserMessage,
@@ -1028,140 +960,53 @@ export const useAgentChatSession = ({
     });
   }, [isHydrating, isStreaming, messages, runPrompt]);
 
-  const editAndResubmit = useCallback(
+  const createBranch = useCallback(
-    async (messageId: string, newContent: string) => {
+    async (messageId: string) => {
       if (isHydrating || isStreaming) return;
 
-      const trimmedContent = newContent.trim();
+      const assistantIndex = messages.findIndex(
-      if (!trimmedContent) return;
+        (message) => message.id === messageId && message.role === "assistant",
-
-      const messageIndex = messages.findIndex((m) => m.id === messageId);
-      if (messageIndex < 0 || messages[messageIndex].role !== "user") return;
-
-      const originalMessage = messages[messageIndex];
-      if (trimmedContent === originalMessage.content.trim()) return;
-
-      const rootMessageId = originalMessage.branchRootId ?? originalMessage.id;
-      const currentSessionId = sessionIdRef.current;
-      const keepMessageCount = messageIndex;
-      const prefix = cloneMessages(messages.slice(0, messageIndex));
-      const originalSuffix = cloneMessages(messages.slice(messageIndex));
-      const forkedSessionId = await forkAgentChat(currentSessionId, keepMessageCount);
-
-      const nextUserMessage = createUserMessage(trimmedContent, rootMessageId);
-      const nextAssistantMessage = createAssistantMessage();
-      const nextSuffix = [nextUserMessage, nextAssistantMessage];
-
-      setBranchGroups((prev) => {
-        const next = cloneBranchGroups(prev);
-        const groupIndex = next.findIndex(
-          (group) =>
-            group.rootMessageId === rootMessageId && group.parentCount === messageIndex,
       );
+      if (assistantIndex < 0) return;
 
-        if (groupIndex >= 0) {
+      const currentSessionId = sessionIdRef.current;
-          const group = next[groupIndex];
+      const keepMessageCount = assistantIndex + 1;
-          group.branches[group.activeIndex] = {
+      const copiedMessages = cloneMessages(messages.slice(0, keepMessageCount));
-            ...group.branches[group.activeIndex],
+      const forkedSessionId = await forkAgentChat(currentSessionId, keepMessageCount);
-            sessionId: currentSessionId,
-            messages: originalSuffix,
-          };
-          group.branches.push({
-            id: createId(),
-            label: `分支 ${group.branches.length + 1}`,
-            sessionId: forkedSessionId,
-            messages: cloneMessages(nextSuffix),
-          });
-          group.activeIndex = group.branches.length - 1;
-        } else {
-          next.push({
-            id: rootMessageId,
-            rootMessageId,
-            parentCount: messageIndex,
-            activeIndex: 1,
-            branches: [
-              {
-                id: createId(),
-                label: "分支 1",
-                sessionId: currentSessionId,
-                messages: originalSuffix,
-              },
-              {
-                id: createId(),
-                label: "分支 2",
-                sessionId: forkedSessionId,
-                messages: cloneMessages(nextSuffix),
-              },
-            ],
-          });
-        }
-
-        return next;
-      });
 
       sessionIdRef.current = forkedSessionId;
       setSessionId(forkedSessionId);
-      await runPrompt({
+      messagesRef.current = copiedMessages;
-        prompt: trimmedContent,
+      setMessages(copiedMessages);
-        sessionIdOverride: forkedSessionId,
+      setIsSessionTitleManuallyEdited(false);
-        preparedMessages: [...prefix, ...nextSuffix],
+      const forkTitle = sessionTitle ? `${sessionTitle} 副本` : "新对话副本";
-        userMessage: nextUserMessage,
+      setSessionTitle(forkTitle);
-        assistantMessage: nextAssistantMessage,
+      try {
+        await saveActiveChatState({
+          title: forkTitle,
+          isTitleManuallyEdited: false,
+          messages: copiedMessages,
+          sessionId: forkedSessionId,
         });
-    },
+        setChatSessions(await listChatSessions());
-    [isHydrating, isStreaming, messages, runPrompt],
+      } catch (error) {
-  );
+        console.error("[GlobalChatbox] Failed to refresh chat sessions after fork:", error);
-
-  const cycleBranch = useCallback(
-    (rootMessageId: string, direction: -1 | 1) => {
-      if (isHydrating || isStreaming) return;
-
-      setBranchGroups((prev) => {
-        const next = cloneBranchGroups(prev);
-        const group = next.find((item) => item.rootMessageId === rootMessageId);
-        if (!group || group.branches.length < 2) {
-          return prev;
       }
-
-        const nextIndex =
-          (group.activeIndex + direction + group.branches.length) % group.branches.length;
-        const selectedBranch = group.branches[nextIndex];
-        group.activeIndex = nextIndex;
-
-      const nextMessages = [
-          ...cloneMessages(messages.slice(0, group.parentCount)),
-          ...cloneMessages(selectedBranch.messages),
-        ];
-        setBranchTransition({
-          rootMessageId,
-          parentCount: group.parentCount,
-          activeBranchId: selectedBranch.id,
-          nonce: Date.now(),
-        });
-        sessionIdRef.current = selectedBranch.sessionId;
-        setSessionId(selectedBranch.sessionId);
-        setMessages(nextMessages);
-
-        return next;
-      });
     },
-    [isHydrating, isStreaming, messages],
+    [isHydrating, isStreaming, messages, sessionTitle],
   );
 
   return {
     messages,
     chatSessions,
     activeSessionId: sessionIdRef.current,
-    branchGroups,
-    branchTransition,
     isHydrating,
     isStreaming,
     sessionTitle,
     sessionId,
     sendPrompt,
     regenerate,
-    editAndResubmit,
+    createBranch,
-    cycleBranch,
     abort,
     replyPermission,
     createSession,