refactor: simplify chat fork flow

2026-06-08 16:07:39 +08:00
parent 34fd5bfb1a
commit 2691f42581
10 changed files with 274 additions and 656 deletions
@@ -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 CloseRounded from "@mui/icons-material/CloseRounded";
-import ChevronLeftRounded from "@mui/icons-material/ChevronLeftRounded";
-import ChevronRightRounded from "@mui/icons-material/ChevronRightRounded";
+import { TbArrowsSplit2 } from "react-icons/tb";
 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;
-  onEditResubmit: (messageId: string, newContent: string) => void;
-  onCycleBranch: (rootMessageId: string, direction: -1 | 1) => void;
+  onRegenerate: (messageId: string) => void;
+  onCreateBranch: (messageId: string) => void;
  onReplyPermission: (requestId: string, reply: PermissionReply) => void;
 };

-const MarkdownBlock = ({ children }: { children: string }) => (
-  <div className={markdownStyles.markdown}>
-    <ReactMarkdown remarkPlugins={[remarkGfm]}>{children}</ReactMarkdown>
-  </div>
-);
+const normalizeClipboardText = (value: string) => value.replace(/\s+$/u, "");
+
+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,
-    onCycleBranch,
+    onCreateBranch,
    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;
@@ -720,185 +721,33 @@ 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={{
-                  p: 2,
-                  borderRadius: 5,
-                  borderBottomRightRadius: 2,
-                  color: "#fff",
-                  background: `linear-gradient(135deg, #0288d1, #00acc1)`,
-                  boxShadow: `0 8px 24px -8px ${alpha("#00acc1", 0.5)}, inset 0 2px 4px ${alpha("#fff", 0.2)}`,
-                  backdropFilter: "blur(10px)",
-                  "--chat-md-text": alpha("#fff", 0.96),
-                  "--chat-md-heading": "#fff",
-                  "--chat-md-link": "#e0f7fa",
-                  "--chat-md-link-hover": "#fff",
-                  "--chat-md-inline-code-bg": "rgba(255,255,255,0.15)",
-                  "--chat-md-inline-code-border": alpha("#fff", 0.1),
-                  "--chat-md-inline-code-text": "#fff",
-                  "--chat-md-pre-bg": "rgba(0, 0, 0, 0.25)",
-                  "--chat-md-pre-border": alpha("#fff", 0.1),
-                  "--chat-md-pre-text": "#F8FAFC",
-                  "--chat-md-quote-border": alpha("#fff", 0.4),
-                  "--chat-md-quote-bg": alpha("#fff", 0.05),
-                  "--chat-md-quote-text": alpha("#fff", 0.8),
-                }}
-              >
-                <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}
-            </>
-          )}
+          <Paper
+            elevation={4}
+            sx={{
+              p: 2,
+              borderRadius: 5,
+              borderBottomRightRadius: 2,
+              color: "#fff",
+              background: `linear-gradient(135deg, #0288d1, #00acc1)`,
+              boxShadow: `0 8px 24px -8px ${alpha("#00acc1", 0.5)}, inset 0 2px 4px ${alpha("#fff", 0.2)}`,
+              backdropFilter: "blur(10px)",
+              "--chat-md-text": alpha("#fff", 0.96),
+              "--chat-md-heading": "#fff",
+              "--chat-md-link": "#e0f7fa",
+              "--chat-md-link-hover": "#fff",
+              "--chat-md-inline-code-bg": "rgba(255,255,255,0.15)",
+              "--chat-md-inline-code-border": alpha("#fff", 0.1),
+              "--chat-md-inline-code-text": "#fff",
+              "--chat-md-pre-bg": "rgba(0, 0, 0, 0.25)",
+              "--chat-md-pre-border": alpha("#fff", 0.1),
+              "--chat-md-pre-text": "#F8FAFC",
+              "--chat-md-quote-border": alpha("#fff", 0.4),
+              "--chat-md-quote-bg": alpha("#fff", 0.05),
+              "--chat-md-quote-text": alpha("#fff", 0.8),
+            }}
+          >
+            <MarkdownBlock>{message.content}</MarkdownBlock>
+          </Paper>
        </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>
              )}
@@ -1088,87 +951,40 @@ 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"
+                  onClick={() => onSpeak(message.id, stripMarkdown(answerContent))}
+                  aria-label="朗读消息"
+                  sx={{ color: "text.secondary", opacity: 0.68, p: 0.5 }}
+                >
+                  <VolumeUpRounded sx={{ fontSize: 16 }} />
+                </IconButton>
+              ) : null}
+              {messageSpeechState === "playing" ? (
                <>
-                  {messageSpeechState === "idle" ? (
-                    <IconButton
-                      size="small"
-                      onClick={() => onSpeak(message.id, stripMarkdown(answerContent))}
-                      aria-label="朗读消息"
-                      sx={{ color: "text.secondary", opacity: 0.68, p: 0.5 }}
-                    >
-                      <VolumeUpRounded sx={{ fontSize: 16 }} />
-                    </IconButton>
-                  ) : null}
-                  {messageSpeechState === "playing" ? (
-                    <>
-                      <IconButton size="small" onClick={onPause} aria-label="暂停朗读" sx={{ color: "primary.main", p: 0.5 }}>
-                        <PauseRounded sx={{ fontSize: 16 }} />
-                      </IconButton>
-                      <IconButton size="small" onClick={onStopSpeech} aria-label="停止朗读" sx={{ color: "error.main", p: 0.5 }}>
-                        <StopRounded sx={{ fontSize: 16 }} />
-                      </IconButton>
-                    </>
-                  ) : null}
-                  {messageSpeechState === "paused" ? (
-                    <>
-                      <IconButton size="small" onClick={onResume} aria-label="继续朗读" sx={{ color: "primary.main", p: 0.5 }}>
-                        <PlayArrowRounded sx={{ fontSize: 16 }} />
-                      </IconButton>
-                      <IconButton size="small" onClick={onStopSpeech} aria-label="停止朗读" sx={{ color: "error.main", p: 0.5 }}>
-                        <StopRounded sx={{ fontSize: 16 }} />
-                      </IconButton>
-                    </>
-                  ) : null}
+                  <IconButton size="small" onClick={onPause} aria-label="暂停朗读" sx={{ color: "primary.main", p: 0.5 }}>
+                    <PauseRounded sx={{ fontSize: 16 }} />
+                  </IconButton>
+                  <IconButton size="small" onClick={onStopSpeech} aria-label="停止朗读" sx={{ color: "error.main", p: 0.5 }}>
+                    <StopRounded sx={{ fontSize: 16 }} />
+                  </IconButton>
+                </>
+              ) : null}
+              {messageSpeechState === "paused" ? (
+                <>
+                  <IconButton size="small" onClick={onResume} aria-label="继续朗读" sx={{ color: "primary.main", p: 0.5 }}>
+                    <PlayArrowRounded sx={{ fontSize: 16 }} />
+                  </IconButton>
+                  <IconButton size="small" onClick={onStopSpeech} aria-label="停止朗读" sx={{ color: "error.main", p: 0.5 }}>
+                    <StopRounded sx={{ fontSize: 16 }} />
+                  </IconButton>
                </>
              ) : 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>
@@ -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(),
-    onCycleBranch: jest.fn(),
+    onCreateBranch: jest.fn(),
    onReplyPermission: jest.fn(),
  };

@@ -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;
-  onEditResubmit: (messageId: string, newContent: string) => void;
-  onCycleBranch: (rootMessageId: string, direction: -1 | 1) => void;
+  onRegenerate: (messageId: string) => void;
+  onCreateBranch: (messageId: string) => 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;
-  onEditResubmit: (messageId: string, newContent: string) => void;
-  onCycleBranch: (rootMessageId: string, direction: -1 | 1) => void;
+  onRegenerate: (messageId: string) => void;
+  onCreateBranch: (messageId: string) => void;
  onReplyPermission: (requestId: string, reply: PermissionReply) => void;
 };

@@ -61,7 +53,6 @@ const sameMessages = (left: Message[], right: Message[]) =>

 const TurnListInner = ({
  messages,
-  branchGroups,
  speakingMessageId,
  speechState,
  onSpeak,
@@ -70,45 +61,26 @@ const TurnListInner = ({
  onStopSpeech,
  isTtsSupported,
  onRegenerate,
-  onEditResubmit,
-  onCycleBranch,
+  onCreateBranch,
  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) => {
-        const rootMessageId = message.branchRootId ?? message.id;
-        return (
-          <AgentTurn
-            key={rootMessageId}
-            message={message}
-            branchState={branchStateByRootId.get(rootMessageId)}
-            messageSpeechState={speakingMessageId === message.id ? speechState : "idle"}
-            onSpeak={onSpeak}
-            onPause={onPauseSpeech}
-            onResume={onResumeSpeech}
-            onStopSpeech={onStopSpeech}
-            isTtsSupported={isTtsSupported}
-            onRegenerate={onRegenerate}
-            onEditResubmit={onEditResubmit}
-            onCycleBranch={onCycleBranch}
-            onReplyPermission={onReplyPermission}
-          />
-        );
-      })}
+      {messages.map((message) => (
+        <AgentTurn
+          key={message.id}
+          message={message}
+          messageSpeechState={speakingMessageId === message.id ? speechState : "idle"}
+          onSpeak={onSpeak}
+          onPause={onPauseSpeech}
+          onResume={onResumeSpeech}
+          onStopSpeech={onStopSpeech}
+          isTtsSupported={isTtsSupported}
+          onRegenerate={onRegenerate}
+          onCreateBranch={onCreateBranch}
+          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.onCycleBranch === nextProps.onCycleBranch &&
+    prevProps.onCreateBranch === nextProps.onCreateBranch &&
    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,
-  onCycleBranch,
+  onCreateBranch,
  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}
-            onCycleBranch={onCycleBranch}
+            onCreateBranch={onCreateBranch}
            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}
-              onCycleBranch={onCycleBranch}
+              onCreateBranch={onCreateBranch}
              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}

@@ -67,15 +67,12 @@ export const GlobalChatbox: React.FC<Props> = ({ open, onClose }) => {
    messages,
    chatSessions,
    activeSessionId,
-    branchGroups,
-    branchTransition,
    isHydrating,
    isStreaming,
    sessionTitle,
    sendPrompt,
    regenerate,
-    editAndResubmit,
-    cycleBranch,
+    createBranch,
    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}
-              onCycleBranch={cycleBranch}
+              onCreateBranch={createBranch}
              onReplyPermission={replyPermission}
            />

@@ -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;
 };
@@ -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),
-    })),
-  }));
@@ -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: [],
      },
    );

@@ -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",
@@ -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);
+  });
 });
@@ -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]);
-
-  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]);
+  }, [isHydrating, isSessionTitleManuallyEdited, isStreaming, messages, projectId, sessionId, sessionTitle]);

  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);
@@ -985,183 +914,99 @@ 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;
-    while (lastUserIndex >= 0 && messages[lastUserIndex].role !== "user") {
-      lastUserIndex--;
+    const targetAssistantIndex = messages.findIndex(
+      (message) => message.id === messageId && message.role === "assistant",
+    );
+    if (targetAssistantIndex < 0) {
+      return;
    }

-    if (lastUserIndex < 0) return;
+    let targetUserIndex = targetAssistantIndex - 1;
+    while (targetUserIndex >= 0 && messages[targetUserIndex].role !== "user") {
+      targetUserIndex--;
+    }

-      const lastUser = messages[lastUserIndex];
-      const lastUserContent = lastUser.content;
-      const nextMessages = cloneMessages(messages.slice(0, lastUserIndex));
-      const nextUserMessage = createUserMessage(
-        lastUserContent,
-        lastUser.branchRootId ?? lastUser.id,
-      );
-      const nextAssistantMessage = createAssistantMessage();
+    if (targetUserIndex < 0) return;

-      setMessages(nextMessages);
-      await runPrompt({
-        prompt: lastUserContent,
-        regenerateFromMessageIndex: lastUserIndex,
-        preparedMessages: [
-          ...nextMessages,
-          nextUserMessage,
-          nextAssistantMessage,
-        ],
-        userMessage: nextUserMessage,
-        assistantMessage: nextAssistantMessage,
-      });
-    }, [isHydrating, isStreaming, messages, runPrompt]);
+    const targetUser = messages[targetUserIndex];
+    const targetUserContent = targetUser.content;
+    const nextMessages = cloneMessages(messages.slice(0, targetUserIndex));
+    const nextUserMessage = createUserMessage(targetUserContent);
+    const nextAssistantMessage = createAssistantMessage();

-  const editAndResubmit = useCallback(
-    async (messageId: string, newContent: string) => {
+    setMessages(nextMessages);
+    await runPrompt({
+      prompt: targetUserContent,
+      regenerateFromMessageIndex: targetUserIndex,
+      preparedMessages: [
+        ...nextMessages,
+        nextUserMessage,
+        nextAssistantMessage,
+      ],
+      userMessage: nextUserMessage,
+      assistantMessage: nextAssistantMessage,
+    });
+  }, [isHydrating, isStreaming, messages, runPrompt]);
+
+  const createBranch = useCallback(
+    async (messageId: string) => {
      if (isHydrating || isStreaming) return;

-      const trimmedContent = newContent.trim();
-      if (!trimmedContent) return;
+      const assistantIndex = messages.findIndex(
+        (message) => message.id === messageId && message.role === "assistant",
+      );
+      if (assistantIndex < 0) return;

-      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 keepMessageCount = assistantIndex + 1;
+      const copiedMessages = cloneMessages(messages.slice(0, keepMessageCount));
      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 (groupIndex >= 0) {
-          const group = next[groupIndex];
-          group.branches[group.activeIndex] = {
-            ...group.branches[group.activeIndex],
-            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({
-        prompt: trimmedContent,
-        sessionIdOverride: forkedSessionId,
-        preparedMessages: [...prefix, ...nextSuffix],
-        userMessage: nextUserMessage,
-        assistantMessage: nextAssistantMessage,
-      });
-    },
-    [isHydrating, isStreaming, messages, runPrompt],
-  );
-
-  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(),
+      messagesRef.current = copiedMessages;
+      setMessages(copiedMessages);
+      setIsSessionTitleManuallyEdited(false);
+      const forkTitle = sessionTitle ? `${sessionTitle} 副本` : "新对话副本";
+      setSessionTitle(forkTitle);
+      try {
+        await saveActiveChatState({
+          title: forkTitle,
+          isTitleManuallyEdited: false,
+          messages: copiedMessages,
+          sessionId: forkedSessionId,
        });
-        sessionIdRef.current = selectedBranch.sessionId;
-        setSessionId(selectedBranch.sessionId);
-        setMessages(nextMessages);
-
-        return next;
-      });
+        setChatSessions(await listChatSessions());
+      } catch (error) {
+        console.error("[GlobalChatbox] Failed to refresh chat sessions after fork:", error);
+      }
    },
-    [isHydrating, isStreaming, messages],
+    [isHydrating, isStreaming, messages, sessionTitle],
  );

  return {
    messages,
    chatSessions,
    activeSessionId: sessionIdRef.current,
-    branchGroups,
-    branchTransition,
    isHydrating,
    isStreaming,
    sessionTitle,
    sessionId,
    sendPrompt,
    regenerate,
-    editAndResubmit,
-    cycleBranch,
+    createBranch,
    abort,
    replyPermission,
    createSession,