feat: implement Undo/Redo/Timeline and Fork Features and fixed opencode.json reading issue on broken json (#99)

* feat: add /undo, /redo, /timeline slash commands and fork button - Add /undo command to revert to previous user message - Add /redo command to redo previously undone messages - Add /timeline command to show conversation history - Add fork button on user messages (hover) to create new session - Add TimelineDialog component for navigating conversation history - Show undo/redo/timeline in autocomplete when session exists - Fix fork to use SDK session.fork API - Silent no-op behavior for undo/redo when no messages (matches OpenCode CLI) * fix: correct fork session endpoint and session switching - Add hybrid SDK approach using v1 for existing methods and v2 for fork only - v2 SDK has correct endpoint /session/{sessionID}/fork instead of broken /session/{id}/fork - Fix forkFromMessage to use setCurrentSession instead of direct set - Ensures both useSessionStore and useSessionManagementStore are consistent - Fixes issue where forked sessions appeared empty until sending a new message * fix: use direct fetch for fork to avoid v2 SDK build errors - Remove v2 SDK imports and hybrid SDK approach - Use direct fetch() call to /api/session/{sessionID}/fork endpoint - Avoids type conflicts between v1 and v2 SDK - Bypasses broken v1 SDK fork endpoint (wrong path parameter) - All codebase now uses v1 SDK consistently * fix: use jsonc-parser for config file parsing - Replace strip-json-comments + JSON.parse with jsonc-parser - Handles comments, trailing commas, and unquoted keys - Matches OpenCode CLI config parsing behavior - Fixes SyntaxError when reading global opencode.json config * feat: improve timeline dialog with loading state and search - Add loading spinner on fork button during operation (~30s on big sessions) - Refresh session list after fork so new session appears in sidebar immediately - Add search bar to filter messages by prompt text content - Show 'No messages found' when search has no results - Disable fork button while forking to prevent duplicate operations
2026-01-03 01:33:35 +02:00
parent da7f0679d8
commit 025a9a6b80
16 changed files with 508 additions and 24 deletions
@@ -3,6 +3,7 @@ import { RiArrowDownLine } from '@remixicon/react';

 import { ChatInput } from './ChatInput';
 import { useSessionStore } from '@/stores/useSessionStore';
+import { useUIStore } from '@/stores/useUIStore';
 import { Skeleton } from '@/components/ui/skeleton';
 import ChatEmptyState from './ChatEmptyState';
 import MessageList from './MessageList';
@@ -11,6 +12,7 @@ import { useChatScrollManager } from '@/hooks/useChatScrollManager';
 import { useDeviceInfo } from '@/lib/device';
 import { Button } from '@/components/ui/button';
 import { OverlayScrollbar } from '@/components/ui/OverlayScrollbar';
+import { TimelineDialog } from './TimelineDialog';

 export const ChatContainer: React.FC = () => {
    const {
@@ -33,6 +35,11 @@ export const ChatContainer: React.FC = () => {
        newSessionDraft,
    } = useSessionStore();

+    const {
+        isTimelineDialogOpen,
+        setTimelineDialogOpen,
+    } = useUIStore();
+
    const streamingMessageId = React.useMemo(() => {
        if (!currentSessionId) return null;
        return streamingMessageIds.get(currentSessionId) ?? null;
@@ -130,6 +137,27 @@ export const ChatContainer: React.FC = () => {
        }
    }, [currentSessionId, isLoadingOlder, loadMoreMessages, scrollRef]);

+    // Scroll to a specific message by ID (for timeline dialog)
+    const scrollToMessage = React.useCallback((messageId: string) => {
+        const container = scrollRef.current;
+        if (!container) return;
+
+        // Find the message element by looking for data-message-id attribute
+        const messageElement = container.querySelector(`[data-message-id="${messageId}"]`) as HTMLElement;
+        if (messageElement) {
+            // Scroll to the message with some padding (50px from top)
+            const containerRect = container.getBoundingClientRect();
+            const messageRect = messageElement.getBoundingClientRect();
+            const offset = 50;
+
+            const scrollTop = messageRect.top - containerRect.top + container.scrollTop - offset;
+            container.scrollTo({
+                top: scrollTop,
+                behavior: 'smooth'
+            });
+        }
+    }, [scrollRef]);
+
    React.useEffect(() => {
        if (!currentSessionId) {
            return;
@@ -199,7 +227,7 @@ export const ChatContainer: React.FC = () => {
                    style={isMobile ? { paddingBottom: 'var(--oc-keyboard-inset, 0px)' } : undefined}
                >
                    <div className="flex-1 overflow-y-auto p-4 bg-background">
-                    <div className="chat-column space-y-4">
+                        <div className="chat-column space-y-4">
                            {[1, 2, 3].map((i) => (
                                <div key={i} className="flex gap-3 p-4">
                                    <Skeleton className="h-8 w-8 rounded-full" />
@@ -246,7 +274,6 @@ export const ChatContainer: React.FC = () => {
                        ref={scrollRef}
                        style={{
                            contain: 'strict',
-
                            ['--scroll-shadow-size' as string]: '48px',
                        }}
                        data-scroll-shadow="true"
@@ -296,6 +323,12 @@ export const ChatContainer: React.FC = () => {
                )}
                <ChatInput scrollToBottom={scrollToBottom} />
            </div>
+
+            <TimelineDialog
+                open={isTimelineDialogOpen}
+                onOpenChange={setTimelineDialogOpen}
+                onScrollToMessage={scrollToMessage}
+            />
        </div>
    );
 };
@@ -82,7 +82,7 @@ export const ChatInput: React.FC<ChatInputProps> = ({ onOpenSettings, scrollToBo

    const { currentProviderId, currentModelId, currentAgentName, setAgent, getVisibleAgents } = useConfigStore();
    const agents = getVisibleAgents();
-    const { isMobile, inputBarOffset, isKeyboardOpen } = useUIStore();
+    const { isMobile, inputBarOffset, isKeyboardOpen, setTimelineDialogOpen } = useUIStore();
    const { working } = useAssistantStatus();
    const [showAbortStatus, setShowAbortStatus] = React.useState(false);
    const abortTimeoutRef = React.useRef<ReturnType<typeof setTimeout> | null>(null);
@@ -355,7 +355,7 @@ export const ChatInput: React.FC<ChatInputProps> = ({ onOpenSettings, scrollToBo
            textareaRef.current?.blur();
        }

-        // Handle /summarize command scroll
+        // Handle slash commands locally before sending
        const normalizedCommand = primaryText.trimStart();
        if (normalizedCommand.startsWith('/')) {
            const commandName = normalizedCommand
@@ -363,7 +363,29 @@ export const ChatInput: React.FC<ChatInputProps> = ({ onOpenSettings, scrollToBo
                .trim()
                .split(/\s+/)[0]
                ?.toLowerCase();
-            if (commandName === 'summarize') {
+
+            // NEW: /undo - revert to last message (populates input with reverted message text)
+            if (commandName === 'undo' && currentSessionId) {
+                await useSessionStore.getState().handleSlashUndo(currentSessionId);
+                // Don't clear message - pendingInputText will populate it with reverted message
+                scrollToBottom?.({ instant: true, force: true });
+                return; // Don't send to assistant
+            }
+            // NEW: /redo - unrevert or partial redo (populates input with message text)
+            else if (commandName === 'redo' && currentSessionId) {
+                await useSessionStore.getState().handleSlashRedo(currentSessionId);
+                // Don't clear message - pendingInputText will populate it
+                scrollToBottom?.({ instant: true, force: true });
+                return; // Don't send to assistant
+            }
+            // NEW: /timeline - open timeline dialog
+            else if (commandName === 'timeline' && currentSessionId) {
+                setTimelineDialogOpen(true);
+                setMessage('');
+                return; // Don't send to assistant
+            }
+            // Existing: /summarize command scroll
+            else if (commandName === 'summarize') {
                scrollToBottom?.({ instant: true, force: true });
            }
        }
@@ -578,12 +578,19 @@ const ChatMessage: React.FC<ChatMessageProps> = ({
    }, [messageTextContent]);

    const revertToMessage = useSessionStore((state) => state.revertToMessage);
+    const forkFromMessage = useSessionStore((state) => state.forkFromMessage);

    const handleRevert = React.useCallback(() => {
        if (!sessionId || !message.info.id) return;
        revertToMessage(sessionId, message.info.id);
    }, [sessionId, message.info.id, revertToMessage]);

+    // NEW: Fork handler
+    const handleFork = React.useCallback(() => {
+        if (!sessionId || !message.info.id) return;
+        forkFromMessage(sessionId, message.info.id);
+    }, [sessionId, message.info.id, forkFromMessage]);
+
    const handleToggleTool = React.useCallback((toolId: string) => {
        setExpandedTools((prev) => {
            const next = new Set(prev);
@@ -788,6 +795,7 @@ const ChatMessage: React.FC<ChatMessageProps> = ({
                                        onAuxiliaryContentComplete={handleAuxiliaryContentComplete}
                                        agentMention={agentMention}
                                        onRevert={handleRevert}
+                                        onFork={isUser ? handleFork : undefined}
                                        errorMessage={assistantErrorText}
                                    />
                                </div>
@@ -1,5 +1,5 @@
 import React from 'react';
-import { RiCommandLine, RiFileLine, RiFlashlightLine, RiRefreshLine, RiScissorsLine, RiTerminalBoxLine } from '@remixicon/react';
+import { RiCommandLine, RiFileLine, RiFlashlightLine, RiRefreshLine, RiScissorsLine, RiTerminalBoxLine, RiArrowGoBackLine, RiArrowGoForwardLine, RiTimeLine } from '@remixicon/react';
 import { cn } from '@/lib/utils';
 import { opencodeClient } from '@/lib/opencode/client';
 import { useSessionStore } from '@/stores/useSessionStore';
@@ -29,15 +29,17 @@ export const CommandAutocomplete = React.forwardRef<CommandAutocompleteHandle, C
  onCommandSelect,
  onClose
 }, ref) => {
-  const { hasMessagesInCurrentSession } = useSessionStore(
+  const { hasMessagesInCurrentSession, currentSessionId } = useSessionStore(
    useShallow((state) => {
      const sessionId = state.currentSessionId;
      const messageCount = sessionId ? (state.messages.get(sessionId)?.length ?? 0) : 0;
      return {
        hasMessagesInCurrentSession: messageCount > 0,
+        currentSessionId: sessionId,
      };
    })
  );
+  const hasSession = Boolean(currentSessionId);

  const [commands, setCommands] = React.useState<CommandInfo[]>([]);
  const [loading, setLoading] = React.useState(false);
@@ -79,9 +81,18 @@ export const CommandAutocomplete = React.forwardRef<CommandAutocompleteHandle, C
        }));

        const builtInCommands: CommandInfo[] = [
-          ...(hasMessagesInCurrentSession
-            ? []
-            : [{ name: 'init', description: 'Create/update AGENTS.md file', isBuiltIn: true }]),
+          ...(hasSession && !hasMessagesInCurrentSession
+            ? [{ name: 'init', description: 'Create/update AGENTS.md file', isBuiltIn: true }]
+            : []
+          ),
+          ...(hasSession  // Show when session exists, not when hasMessages
+            ? [
+                { name: 'undo', description: 'Undo the last message', isBuiltIn: true },
+                { name: 'redo', description: 'Redo previously undone messages', isBuiltIn: true },
+                { name: 'timeline', description: 'Jump to a specific message', isBuiltIn: true },
+              ]
+            : []
+          ),
          { name: 'summarize', description: 'Generate a summary of the current session', isBuiltIn: true },
        ];

@@ -114,9 +125,18 @@ export const CommandAutocomplete = React.forwardRef<CommandAutocompleteHandle, C

        const allowInitCommand = !hasMessagesInCurrentSession;
        const builtInCommands: CommandInfo[] = [
-          ...(hasMessagesInCurrentSession
-            ? []
-            : [{ name: 'init', description: 'Create/update AGENTS.md file', isBuiltIn: true }]),
+          ...(hasSession && !hasMessagesInCurrentSession
+            ? [{ name: 'init', description: 'Create/update AGENTS.md file', isBuiltIn: true }]
+            : []
+          ),
+          ...(hasSession  // Show when session exists, not when hasMessages
+            ? [
+                { name: 'undo', description: 'Undo the last message', isBuiltIn: true },
+                { name: 'redo', description: 'Redo previously undone messages', isBuiltIn: true },
+                { name: 'timeline', description: 'Jump to a specific message', isBuiltIn: true },
+              ]
+            : []
+          ),
          { name: 'summarize', description: 'Generate a summary of the current session', isBuiltIn: true },
        ];

@@ -134,7 +154,7 @@ export const CommandAutocomplete = React.forwardRef<CommandAutocompleteHandle, C
    };

    loadCommands();
-  }, [searchQuery, hasMessagesInCurrentSession]);
+  }, [searchQuery, hasMessagesInCurrentSession, hasSession]);

  React.useEffect(() => {
    setSelectedIndex(0);
@@ -184,6 +204,12 @@ export const CommandAutocomplete = React.forwardRef<CommandAutocompleteHandle, C
    switch (command.name) {
      case 'init':
        return <RiFileLine className="h-3.5 w-3.5 text-green-500" />;
+      case 'undo':
+        return <RiArrowGoBackLine className="h-3.5 w-3.5 text-orange-500" />;
+      case 'redo':
+        return <RiArrowGoForwardLine className="h-3.5 w-3.5 text-orange-500" />;
+      case 'timeline':
+        return <RiTimeLine className="h-3.5 w-3.5 text-blue-500" />;
      case 'summarize':
        return <RiScissorsLine className="h-3.5 w-3.5 text-purple-500" />;
      case 'test':
@@ -0,0 +1,202 @@
+import React from 'react';
+import {
+    Dialog,
+    DialogContent,
+    DialogDescription,
+    DialogHeader,
+    DialogTitle,
+} from '@/components/ui/dialog';
+import { Button } from '@/components/ui/button';
+import { Input } from '@/components/ui/input';
+import { useSessionStore } from '@/stores/useSessionStore';
+import { useMessageStore } from '@/stores/messageStore';
+import { cn } from '@/lib/utils';
+import { RiLoader4Line, RiSearchLine, RiTimeLine, RiGitBranchLine } from '@remixicon/react';
+import type { Part } from '@opencode-ai/sdk';
+
+interface TimelineDialogProps {
+    open: boolean;
+    onOpenChange: (open: boolean) => void;
+    onScrollToMessage?: (messageId: string) => void;
+}
+
+// Helper: format relative time (e.g., "2 hours ago")
+function formatRelativeTime(timestamp: number): string {
+    const now = Date.now();
+    const diffMs = now - timestamp;
+    const diffSecs = Math.floor(diffMs / 1000);
+    const diffMins = Math.floor(diffSecs / 60);
+    const diffHours = Math.floor(diffMins / 60);
+    const diffDays = Math.floor(diffHours / 24);
+
+    if (diffSecs < 60) return 'just now';
+    if (diffMins < 60) return `${diffMins}m ago`;
+    if (diffHours < 24) return `${diffHours}h ago`;
+    if (diffDays < 7) return `${diffDays}d ago`;
+    return new Date(timestamp).toLocaleDateString();
+}
+
+export const TimelineDialog: React.FC<TimelineDialogProps> = ({ open, onOpenChange, onScrollToMessage }) => {
+    const currentSessionId = useSessionStore((state) => state.currentSessionId);
+    const messages = useMessageStore((state) =>
+        currentSessionId ? state.messages.get(currentSessionId) || [] : []
+    );
+    const revertToMessage = useSessionStore((state) => state.revertToMessage);
+    const forkFromMessage = useSessionStore((state) => state.forkFromMessage);
+    const loadSessions = useSessionStore((state) => state.loadSessions);
+
+    const [forkingMessageId, setForkingMessageId] = React.useState<string | null>(null);
+    const [searchQuery, setSearchQuery] = React.useState('');
+
+    // Filter user messages (reversed for newest first)
+    const userMessages = React.useMemo(() => {
+        const filtered = messages.filter(m => m.info.role === 'user');
+        return filtered.reverse();
+    }, [messages]);
+
+    // Filter by search query
+    const filteredMessages = React.useMemo(() => {
+        if (!searchQuery.trim()) return userMessages;
+
+        const query = searchQuery.toLowerCase();
+        return userMessages.filter((message) => {
+            const preview = getMessagePreview(message.parts).toLowerCase();
+            return preview.includes(query);
+        });
+    }, [userMessages, searchQuery]);
+
+    // Handle fork with loading state and session refresh
+    const handleFork = async (messageId: string) => {
+        if (!currentSessionId) return;
+        setForkingMessageId(messageId);
+        try {
+            await forkFromMessage(currentSessionId, messageId);
+            await loadSessions();
+            onOpenChange(false);
+        } finally {
+            setForkingMessageId(null);
+        }
+    };
+
+    if (!currentSessionId) return null;
+
+    return (
+        <Dialog open={open} onOpenChange={onOpenChange}>
+            <DialogContent className="max-w-2xl max-h-[70vh] flex flex-col">
+                <DialogHeader>
+                    <DialogTitle className="flex items-center gap-2">
+                        <RiTimeLine className="h-5 w-5" />
+                        Conversation Timeline
+                    </DialogTitle>
+                    <DialogDescription>
+                        Navigate to any point in the conversation or fork a new session
+                    </DialogDescription>
+                </DialogHeader>
+
+                <div className="flex items-center gap-2 mt-2">
+                    <RiSearchLine className="h-4 w-4 text-muted-foreground" />
+                    <Input
+                        placeholder="Search messages..."
+                        value={searchQuery}
+                        onChange={(e) => setSearchQuery(e.target.value)}
+                        className="flex-1"
+                    />
+                </div>
+
+                <div className="flex-1 overflow-y-auto space-y-2">
+                    {filteredMessages.length === 0 ? (
+                        <div className="text-center text-muted-foreground py-8">
+                            {searchQuery ? 'No messages found' : 'No messages in this session yet'}
+                        </div>
+                    ) : (
+                        filteredMessages.map((message) => {
+                            const preview = getMessagePreview(message.parts);
+                            const timestamp = message.info.time.created;
+                            const relativeTime = formatRelativeTime(timestamp);
+
+                            return (
+                                <div
+                                    key={message.info.id}
+                                    className={cn(
+                                        "group flex items-start gap-3 p-3 rounded-lg border transition-all",
+                                        "hover:border-primary/50 hover:bg-muted/30"
+                                    )}
+                                >
+                                    <div className="flex-1 min-w-0">
+                                        <div className="flex items-center gap-2">
+                                            <span className="typography-meta text-muted-foreground">
+                                                Message {userMessages.length - userMessages.indexOf(message)}
+                                            </span>
+                                            <span className="typography-meta text-muted-foreground">
+                                                •
+                                            </span>
+                                            <span className="typography-meta text-muted-foreground">
+                                                {relativeTime}
+                                            </span>
+                                        </div>
+                                        <p className="typography-small text-foreground mt-1 line-clamp-2">
+                                            {preview || '[No text content]'}
+                                        </p>
+                                    </div>
+
+                                    <div className="flex gap-2 opacity-0 group-hover:opacity-100 transition-opacity">
+                                        <Button
+                                            size="sm"
+                                            variant="outline"
+                                            onClick={() => {
+                                                onScrollToMessage?.(message.info.id);
+                                                onOpenChange(false);
+                                            }}
+                                        >
+                                            Go here
+                                        </Button>
+
+                                        <Button
+                                            size="sm"
+                                            variant="default"
+                                            onClick={async () => {
+                                                await revertToMessage(currentSessionId, message.info.id);
+                                                onOpenChange(false);
+                                            }}
+                                        >
+                                            Revert
+                                        </Button>
+
+                                        <Button
+                                            size="sm"
+                                            variant="secondary"
+                                            onClick={() => handleFork(message.info.id)}
+                                            disabled={forkingMessageId === message.info.id}
+                                        >
+                                            {forkingMessageId === message.info.id ? (
+                                                <RiLoader4Line className="h-4 w-4 animate-spin" />
+                                            ) : 'Fork'}
+                                        </Button>
+                                    </div>
+                                </div>
+                            );
+                        })
+                    )}
+                </div>
+
+                <div className="mt-4 p-3 bg-muted/30 rounded-lg">
+                    <div className="flex items-start gap-2 typography-meta text-muted-foreground">
+                        <RiGitBranchLine className="h-4 w-4 mt-0.5" />
+                        <div>
+                            <p className="font-medium mb-1">Actions</p>
+                            <p>• <strong>Go here</strong> - Scroll to this message in the conversation</p>
+                            <p>• <strong>Revert</strong> - Undo to this point (message text will populate input)</p>
+                            <p>• <strong>Fork</strong> - Create a new session starting from here</p>
+                        </div>
+                    </div>
+                </div>
+            </DialogContent>
+        </Dialog>
+    );
+};
+
+function getMessagePreview(parts: Part[]): string {
+    const textPart = parts.find(p => p.type === 'text');
+    if (!textPart || typeof textPart.text !== 'string') return '';
+    return textPart.text.replace(/\n/g, ' ').slice(0, 80);
+}
@@ -16,7 +16,7 @@ import { isEmptyTextPart, extractTextContent } from './partUtils';
 import { FadeInOnReveal } from './FadeInOnReveal';
 import { Button } from '@/components/ui/button';
 import { Tooltip, TooltipContent, TooltipTrigger } from '@/components/ui/tooltip';
-import { RiCheckLine, RiFileCopyLine, RiChatNewLine, RiArrowGoBackLine } from '@remixicon/react';
+import { RiCheckLine, RiFileCopyLine, RiChatNewLine, RiArrowGoBackLine, RiGitBranchLine } from '@remixicon/react';
 import { ArrowsMerge } from '@/components/icons/ArrowsMerge';
 import type { ContentChangeReason } from '@/hooks/useChatScrollManager';

@@ -133,6 +133,7 @@ interface MessageBodyProps {
    agentMention?: AgentMentionInfo;
    turnGroupingContext?: TurnGroupingContext;
    onRevert?: () => void;
+    onFork?: () => void;
    errorMessage?: string;
 }

@@ -147,7 +148,8 @@ const UserMessageBody: React.FC<{
    onShowPopup: (content: ToolPopupContent) => void;
    agentMention?: AgentMentionInfo;
    onRevert?: () => void;
-}> = ({ messageId, parts, isMobile, hasTouchInput, hasTextContent, onCopyMessage, copiedMessage, onShowPopup, agentMention, onRevert }) => {
+    onFork?: () => void;
+}> = ({ messageId, parts, isMobile, hasTouchInput, hasTextContent, onCopyMessage, copiedMessage, onShowPopup, agentMention, onRevert, onFork }) => {
    const [copyHintVisible, setCopyHintVisible] = React.useState(false);
    const copyHintTimeoutRef = React.useRef<number | null>(null);

@@ -239,7 +241,7 @@ const UserMessageBody: React.FC<{
                })}
            </div>
            <MessageFilesDisplay files={parts} onShowPopup={onShowPopup} />
-            {(canCopyMessage && hasCopyableText) || onRevert ? (
+            {(canCopyMessage && hasCopyableText) || onRevert || onFork ? (
                <div className={cn(
                    "mt-1 flex items-center justify-end gap-2 opacity-0 pointer-events-none transition-opacity duration-150 group-hover/message:opacity-100 group-hover/message:pointer-events-auto focus-within:opacity-100 focus-within:pointer-events-auto",
                    copyHintVisible && "opacity-100 pointer-events-auto"
@@ -265,6 +267,26 @@ const UserMessageBody: React.FC<{
                            <TooltipContent sideOffset={6}>Revert from here</TooltipContent>
                        </Tooltip>
                    )}
+                    {onFork && (
+                        <Tooltip delayDuration={1000}>
+                            <TooltipTrigger asChild>
+                                <Button
+                                    type="button"
+                                    variant="ghost"
+                                    size="icon"
+                                    className="h-8 w-8 text-muted-foreground bg-transparent hover:text-foreground hover:!bg-transparent active:!bg-transparent focus-visible:!bg-transparent focus-visible:ring-2 focus-visible:ring-primary/50"
+                                    onPointerDown={(event) => event.stopPropagation()}
+                                    onClick={(event) => {
+                                        event.stopPropagation();
+                                        onFork();
+                                    }}
+                                >
+                                    <RiGitBranchLine className="h-3.5 w-3.5" />
+                                </Button>
+                            </TooltipTrigger>
+                            <TooltipContent sideOffset={6}>Fork from here</TooltipContent>
+                        </Tooltip>
+                    )}
                    {canCopyMessage && hasCopyableText && (
                        <Tooltip delayDuration={1000}>
                            <TooltipTrigger asChild>
@@ -1226,6 +1248,7 @@ const MessageBody: React.FC<MessageBodyProps> = ({ isUser, ...props }) => {
                onShowPopup={props.onShowPopup}
                agentMention={props.agentMention}
                onRevert={props.onRevert}
+                onFork={props.onFork}
            />
        );
    }
@@ -664,6 +664,28 @@ class OpencodeService {
    return response.data;
  }

+  async forkSession(sessionId: string, messageId?: string): Promise<Session> {
+    const baseUrl = this.baseUrl.replace(/\/$/, '');
+    const url = new URL(`/api/session/${sessionId}/fork`, baseUrl);
+
+    if (this.currentDirectory) {
+      url.searchParams.set('directory', this.currentDirectory);
+    }
+
+    const response = await fetch(url.toString(), {
+      method: 'POST',
+      headers: { 'Content-Type': 'application/json' },
+      body: JSON.stringify(messageId ? { messageID: messageId } : {}),
+    });
+
+    if (!response.ok) {
+      const text = await response.text();
+      throw new Error(`Failed to fork session: ${text || response.statusText}`);
+    }
+
+    return response.json();
+  }
+
  async getSessionStatus(): Promise<
    Record<string, { type: "idle" | "busy" | "retry"; attempt?: number; message?: string; next?: number }>
  > {
@@ -192,6 +192,9 @@ export interface SessionStore {
     updateSession: (session: Session) => void;

     revertToMessage: (sessionId: string, messageId: string) => Promise<void>;
+     handleSlashUndo: (sessionId: string) => Promise<void>;
+     handleSlashRedo: (sessionId: string) => Promise<void>;
+     forkFromMessage: (sessionId: string, messageId: string) => Promise<void>;
     setPendingInputText: (text: string | null) => void;
     consumePendingInputText: () => string | null;
 }
@@ -553,6 +553,139 @@ export const useSessionStore = create<SessionStore>()(
                    }
                },

+                handleSlashUndo: async (sessionId: string) => {
+                    const messages = get().messages.get(sessionId) || [];
+                    const userMessages = messages.filter(m => m.info.role === 'user');
+                    const sessions = get().sessions;
+                    const currentSession = sessions.find(s => s.id === sessionId);
+
+                    // Silent no-op like OpenCode CLI
+                    if (userMessages.length === 0) {
+                        return;
+                    }
+
+                    // Get current revert state to determine which message to undo next
+                    const revertToId = currentSession?.revert?.messageID;
+
+                    // Find the user message AFTER the revert point (or last message if no revert)
+                    let targetMessage;
+                    if (revertToId) {
+                        const revertIndex = userMessages.findIndex(m => m.info.id === revertToId);
+                        targetMessage = userMessages[revertIndex + 1];
+                    } else {
+                        targetMessage = userMessages[userMessages.length - 1];
+                    }
+
+                    // Silent no-op like OpenCode CLI
+                    if (!targetMessage) {
+                        return;
+                    }
+
+                    // Helper to extract text preview
+                    const textPart = targetMessage.parts.find(p => p.type === 'text');
+                    const preview = typeof textPart === 'object' && textPart && 'text' in textPart
+                        ? String(textPart.text).slice(0, 50) + (String(textPart.text).length > 50 ? '...' : '')
+                        : '[No text]';
+
+                    await get().revertToMessage(sessionId, targetMessage.info.id);
+
+                    const { toast } = await import('sonner');
+                    toast.success(`Undid to: ${preview}`);
+                },
+
+                handleSlashRedo: async (sessionId: string) => {
+                    const sessions = get().sessions;
+                    const currentSession = sessions.find(s => s.id === sessionId);
+                    const revertToId = currentSession?.revert?.messageID;
+
+                    // Silent no-op like OpenCode CLI
+                    if (!revertToId) {
+                        return;
+                    }
+
+                    const messages = get().messages.get(sessionId) || [];
+                    const userMessages = messages.filter(m => m.info.role === 'user');
+
+                    // Find the user message BEFORE the revert point
+                    const revertIndex = userMessages.findIndex(m => m.info.id === revertToId);
+                    const targetMessage = userMessages[revertIndex - 1];
+
+                    if (targetMessage) {
+                        // Partial redo: move to previous message
+                        const textPart = targetMessage.parts.find(p => p.type === 'text');
+                        const preview = typeof textPart === 'object' && textPart && 'text' in textPart
+                            ? String(textPart.text).slice(0, 50) + (String(textPart.text).length > 50 ? '...' : '')
+                            : '[No text]';
+
+                        await get().revertToMessage(sessionId, targetMessage.info.id);
+
+                        const { toast } = await import('sonner');
+                        toast.success(`Redid to: ${preview}`);
+                    } else {
+                        // Full unrevert: restore all
+                        const session = await opencodeClient.unrevertSession(sessionId);
+                        await useSessionManagementStore.getState().updateSession(session);
+                        await get().loadMessages(sessionId);
+
+                        const { toast } = await import('sonner');
+                        toast.success('Restored all messages');
+                    }
+                },
+
+                forkFromMessage: async (sessionId: string, messageId: string) => {
+                    const sessions = get().sessions;
+                    const existingSession = sessions.find(s => s.id === sessionId);
+                    if (!existingSession) return;
+
+                    try {
+                        // 1. Call SDK fork - backend copies all messages up to messageId
+                        const result = await opencodeClient.forkSession(sessionId, messageId);
+
+                        if (!result || !result.id) {
+                            const { toast } = await import('sonner');
+                            toast.error('Failed to fork session');
+                            return;
+                        }
+
+                        // 2. Extract fork point content for input field (text + file attachments)
+                        const messages = get().messages.get(sessionId) || [];
+                        const message = messages.find(m => m.info.id === messageId);
+
+                        if (!message) {
+                            const { toast } = await import('sonner');
+                            toast.error('Message not found');
+                            return;
+                        }
+
+                        // Extract text content from non-synthetic, non-ignored text parts
+                        let inputText = '';
+                        for (const part of message.parts) {
+                            if (part.type === 'text' && !part.synthetic && !part.ignored) {
+                                const typedPart = part as { text?: string };
+                                inputText += typedPart.text || '';
+                            }
+                        }
+
+                        // 3. Switch to new session
+                        get().setCurrentSession(result.id);
+
+                        // 4. Show fork point as pending input (will populate ChatInput)
+                        if (inputText) {
+                            set({ pendingInputText: inputText });
+                        }
+
+                        // Load the new session's messages
+                        await get().loadMessages(result.id);
+
+                        const { toast } = await import('sonner');
+                        toast.success(`Forked from ${existingSession.title}`);
+                    } catch (error) {
+                        console.error('Failed to fork session:', error);
+                        const { toast } = await import('sonner');
+                        toast.error('Failed to fork session');
+                    }
+                },
+
                setPendingInputText: (text: string | null) => {
                    set({ pendingInputText: text });
                },
@@ -52,6 +52,7 @@ interface UIStore {
  diffLayoutPreference: 'dynamic' | 'inline' | 'side-by-side';
  diffFileLayout: Record<string, 'inline' | 'side-by-side'>;
  diffWrapLines: boolean;
+  isTimelineDialogOpen: boolean;

  setTheme: (theme: 'light' | 'dark' | 'system') => void;
  toggleSidebar: () => void;
@@ -93,6 +94,7 @@ interface UIStore {
  setDiffFileLayout: (filePath: string, mode: 'inline' | 'side-by-side') => void;
  setDiffWrapLines: (wrap: boolean) => void;
  setMultiRunLauncherOpen: (open: boolean) => void;
+  setTimelineDialogOpen: (open: boolean) => void;
  openMultiRunLauncher: () => void;
  openMultiRunLauncherWithPrompt: (prompt: string) => void;
 }
@@ -135,6 +137,7 @@ export const useUIStore = create<UIStore>()(
        diffLayoutPreference: 'dynamic',
        diffFileLayout: {},
        diffWrapLines: false,
+        isTimelineDialogOpen: false,

        setTheme: (theme) => {
          set({ theme });
@@ -458,6 +461,10 @@ export const useUIStore = create<UIStore>()(
            isSessionSwitcherOpen: false,
          });
        },
+
+        setTimelineDialogOpen: (open) => {
+          set({ isTimelineDialogOpen: open });
+        },
      }),
      {
        name: 'ui-store',