import React, { PureComponent } from 'react';
import Drawer from '@mui/material/Drawer';
import Box from '@mui/material/Box';
import Typography from '@mui/material/Typography';
import IconButton from '@mui/material/IconButton';
import Button from '@mui/material/Button';
import InputBase from '@mui/material/InputBase';
import MenuItem from '@mui/material/MenuItem';
import Select from '@mui/material/Select';
import FormControl from '@mui/material/FormControl';
import InputLabel from '@mui/material/InputLabel';
import CircularProgress from '@mui/material/CircularProgress';
import CloseRoundedIcon from '@mui/icons-material/CloseRounded';
import SendRoundedIcon from '@mui/icons-material/SendRounded';
import AddRoundedIcon from '@mui/icons-material/AddRounded';
import AutoAwesomeRoundedIcon from '@mui/icons-material/AutoAwesomeRounded';
import DeleteOutlineRoundedIcon from '@mui/icons-material/DeleteOutlineRounded';

import Tooltip from '@mui/material/Tooltip';
import Badge from '@mui/material/Badge';
import Divider from '@mui/material/Divider';
import AttachFileRoundedIcon from '@mui/icons-material/AttachFileRounded';
import TuneRoundedIcon from '@mui/icons-material/TuneRounded';
import ElderlyRoundedIcon from '@mui/icons-material/ElderlyRounded';
import DirectionsWalkRoundedIcon from '@mui/icons-material/DirectionsWalkRounded';
import DirectionsRunRoundedIcon from '@mui/icons-material/DirectionsRunRounded';
import PsychologyRoundedIcon from '@mui/icons-material/PsychologyRounded';
import FolderOpenRoundedIcon from '@mui/icons-material/FolderOpenRounded';

import { setting as settingApi } from '../../api';
import chatAutomat, { selectPendingAskUser } from '../../automats/chatAutomat';
import userSettingsAutomat from '../../automats/userSettingsAutomat';
import vfsAutomat from '../../automats/vfsAutomat';
import { VfsEditorPanel, VfsFileIcon } from '../vfs';
import ChatFlowList from './ChatFlowList';
import AskUserPrompt from './AskUserPrompt';
import { ACCEPT_STRING, readFileAttachment } from './chatAttachments';
import { ChatStagedAttachmentsTray } from './ChatAttachmentItems';
import {
  BLUE_GLOW,
  SHADOW_DRAWER,
} from '../../colors';

const DEFAULT_DRAWER_WIDTH = 460;
const MIN_DRAWER_WIDTH = 320;

export default class ChatDrawer extends PureComponent {

  constructor(props) {
    super(props);
    const s = chatAutomat.state;
    const settings = userSettingsAutomat.state;
    const vfs = vfsAutomat.state;
    this.state = {
      isOpen: s.isOpen,
      isVfsOpen: vfs.isOpen,
      vfsWidth: vfs.vfsWidth || 480,
      conversations: s.conversations,
      selectedConversationId: s.selectedConversationId,
      draftConversation: s.draftConversation,
      conversationState: s.conversationState,
      provider: s.provider,
      model: s.model,
      messages: s.messages,
      loadingMessages: s.loadingMessages,
      streamingText: s.streamingText,
      isSending: s.isSending,
      loadingConversations: s.loadingConversations,
      sseStatus: s.sseStatus,
      sendError: s.sendError,
      activeTurns: s.activeTurns || [],
      inputText: '',
      isInputFocused: false,
      stagedAttachments: [],
      stagedReferences: [],
      isProcessingFiles: false,
      isDraggingFiles: false,
      attachmentError: null,
      drawerWidth: settings?.chatDrawerWidth || DEFAULT_DRAWER_WIDTH,
      isResizing: false,
      showSettingsBar: false,
      modelslugflag: 'floor',
      modelreasoning: 'medium',
      modelslug: 'openai/gpt-6-luna',
    };
    this.inputRef = React.createRef();
    this.fileInputRef = React.createRef();
    this.focusTimeout = null;
  }

  focusInput = (delay = 50) => {
    if (this.focusTimeout) clearTimeout(this.focusTimeout);
    this.focusTimeout = setTimeout(() => {
      this.inputRef.current?.focus?.();
    }, delay);
  };

  componentDidMount() {
    if (this.state.isOpen) {
      this.focusInput(150);
    }
    void this.loadModelSettings();
    this.unsub = chatAutomat.subscribe(this, (state) => {
      const wasOpen = this.state.isOpen;
      const willOpen = state.isOpen;
      if (!wasOpen && willOpen) {
        this.focusInput(150);
      }
      return {
        isOpen: state.isOpen,
        conversations: state.conversations,
        selectedConversationId: state.selectedConversationId,
        draftConversation: state.draftConversation,
        conversationState: state.conversationState,
        provider: state.provider,
        model: state.model,
        messages: state.messages,
        loadingMessages: state.loadingMessages,
        streamingText: state.streamingText,
        isSending: state.isSending,
        loadingConversations: state.loadingConversations,
        sseStatus: state.sseStatus,
        sendError: state.sendError,
        activeTurns: state.activeTurns || [],
      };
    });

    this.unsubSettings = userSettingsAutomat.subscribe(this, (state) => {
      if (!this.state.isResizing) {
        return { drawerWidth: state.chatDrawerWidth || DEFAULT_DRAWER_WIDTH };
      }
      return null;
    });

    this.unsubVfs = vfsAutomat.subscribe(this, (state) => ({
      isVfsOpen: state.isOpen,
      vfsWidth: state.vfsWidth,
    }));
  }

  componentWillUnmount() {
    if (this.focusTimeout) clearTimeout(this.focusTimeout);
    this.unsub?.();
    this.unsubSettings?.();
    this.unsubVfs?.();
    this.cleanupResizeListeners();
  }

  handleClose = () => {
    chatAutomat.actions.closeChat();
  };

  handleInsertToChat = (text) => {
    // If it's a file / line tag, e.g. [file.js#L10-L20](file.js#L10-L20) or [file.js](file.js)
    const match =
      typeof text === 'string' &&
      text.trim().match(/^(!?)\[([^#\]]+)(?:#L?(\d+)(?:-L?(\d+))?)?\]\(([^)]+)\)$/);
    if (match) {
      const [, isImg, fileName, startLine, endLine, path] = match;
      this.handleMentionReference({
        fileName,
        path,
        startLine: startLine ? parseInt(startLine, 10) : null,
        endLine: endLine ? parseInt(endLine, 10) : (startLine ? parseInt(startLine, 10) : null),
        isImage: Boolean(isImg),
      });
      return;
    }
    this.setState((prev) => ({
      inputText: prev.inputText ? `${prev.inputText}\n${text}` : text,
    }));
    this.focusInput(50);
  };

  handleMentionReference = (refData) => {
    if (!refData || !refData.fileName) return;
    const {
      fileName,
      path = refData.fileName,
      startLine = null,
      endLine = null,
      selectedText = '',
      isImage = false,
    } = refData;

    this.setState((prev) => {
      const exists = prev.stagedReferences.some(
        (r) => r.fileName === fileName && r.startLine === startLine && r.endLine === endLine
      );
      if (exists) {
        return null;
      }
      const newRef = {
        id: `ref-${Date.now()}-${Math.random().toString(36).slice(2, 7)}`,
        fileName,
        path,
        startLine,
        endLine,
        selectedText,
        isImage,
      };
      return {
        stagedReferences: [...prev.stagedReferences, newRef],
      };
    });
    this.focusInput(50);
  };

  handleRemoveReference = (id) => {
    this.setState((prev) => ({
      stagedReferences: prev.stagedReferences.filter((r) => r.id !== id),
    }));
    this.focusInput(50);
  };

  handleVfsResizerStart = (e) => {
    if (e.button !== undefined && e.button !== 0) return;
    e.preventDefault();
    e.stopPropagation();

    const startX = e.clientX ?? (e.touches && e.touches[0]?.clientX);
    if (startX === undefined) return;

    const startVfsWidth = this.state.vfsWidth;
    const startChatWidth = this.state.drawerWidth;
    const totalPairWidth = startVfsWidth + startChatWidth;

    this.setState({ isResizing: true });
    document.body.style.cursor = 'col-resize';
    document.body.style.userSelect = 'none';

    let currentChatWidth = startChatWidth;
    let currentVfsWidth = startVfsWidth;

    const onMove = (moveEvt) => {
      moveEvt.preventDefault();
      const clientX = moveEvt.clientX ?? (moveEvt.touches && moveEvt.touches[0]?.clientX);
      if (clientX === undefined) return;

      const deltaX = clientX - startX;
      const minVfs = 260;
      const minChat = MIN_DRAWER_WIDTH; // 320

      // Drag right (deltaX > 0): VFS increases, Chat decreases
      // Drag left (deltaX < 0): VFS decreases, Chat increases
      const clampedVfs = Math.max(minVfs, Math.min(totalPairWidth - minChat, Math.round(startVfsWidth + deltaX)));
      const clampedChat = totalPairWidth - clampedVfs;

      currentVfsWidth = clampedVfs;
      currentChatWidth = clampedChat;

      vfsAutomat.actions.setVfsWidth(clampedVfs);
      this.setState({ drawerWidth: clampedChat });
    };

    const onEnd = () => {
      document.body.style.cursor = '';
      document.body.style.userSelect = '';
      window.removeEventListener('pointermove', onMove);
      window.removeEventListener('pointerup', onEnd);
      window.removeEventListener('pointercancel', onEnd);
      window.removeEventListener('mousemove', onMove);
      window.removeEventListener('mouseup', onEnd);
      window.removeEventListener('touchmove', onMove);
      window.removeEventListener('touchend', onEnd);

      this.setState({ isResizing: false });
      vfsAutomat.actions.setVfsWidth(currentVfsWidth);
      userSettingsAutomat.actions.setChatDrawerWidth(currentChatWidth);
    };

    window.addEventListener('pointermove', onMove, { passive: false });
    window.addEventListener('pointerup', onEnd);
    window.addEventListener('pointercancel', onEnd);
    window.addEventListener('mousemove', onMove, { passive: false });
    window.addEventListener('mouseup', onEnd);
    window.addEventListener('touchmove', onMove, { passive: false });
    window.addEventListener('touchend', onEnd);
  };

  handleResizeStart = (e) => {
    if (e.button !== undefined && e.button !== 0) return;
    e.preventDefault();
    e.stopPropagation();

    const startX = e.clientX ?? (e.touches && e.touches[0]?.clientX);
    if (startX === undefined) return;

    const startWidth = this.state.drawerWidth;
    const startVfsWidth = this.state.vfsWidth;
    const isVfs = this.state.isVfsOpen;

    this.setState({ isResizing: true });
    document.body.style.cursor = 'col-resize';
    document.body.style.userSelect = 'none';

    let currentChatWidth = startWidth;
    let currentVfsWidth = startVfsWidth;

    const onMove = (moveEvt) => {
      moveEvt.preventDefault();
      const clientX = moveEvt.clientX ?? (moveEvt.touches && moveEvt.touches[0]?.clientX);
      if (clientX === undefined) return;

      const deltaX = startX - clientX;

      if (isVfs) {
        const maxVfs = Math.min(window.innerWidth - startWidth - 40, 1200);
        const newVfsWidth = Math.max(260, Math.min(maxVfs, Math.round(startVfsWidth + deltaX)));
        currentVfsWidth = newVfsWidth;
        vfsAutomat.actions.setVfsWidth(newVfsWidth);
      } else {
        const maxWidth = Math.min(window.innerWidth - 40, 1400);
        const newWidth = Math.max(MIN_DRAWER_WIDTH, Math.min(maxWidth, Math.round(startWidth + deltaX)));
        currentChatWidth = newWidth;
        this.setState({ drawerWidth: newWidth });
      }
    };

    const onEnd = () => {
      document.body.style.cursor = '';
      document.body.style.userSelect = '';
      window.removeEventListener('pointermove', onMove);
      window.removeEventListener('pointerup', onEnd);
      window.removeEventListener('pointercancel', onEnd);
      window.removeEventListener('mousemove', onMove);
      window.removeEventListener('mouseup', onEnd);
      window.removeEventListener('touchmove', onMove);
      window.removeEventListener('touchend', onEnd);

      this.setState({ isResizing: false });
      if (isVfs) {
        vfsAutomat.actions.setVfsWidth(currentVfsWidth);
      } else {
        userSettingsAutomat.actions.setChatDrawerWidth(currentChatWidth);
      }
    };

    window.addEventListener('pointermove', onMove, { passive: false });
    window.addEventListener('pointerup', onEnd);
    window.addEventListener('pointercancel', onEnd);
    window.addEventListener('mousemove', onMove, { passive: false });
    window.addEventListener('mouseup', onEnd);
    window.addEventListener('touchmove', onMove, { passive: false });
    window.addEventListener('touchend', onEnd);
  };

  handleResizeDoubleClick = () => {
    this.setState({ drawerWidth: DEFAULT_DRAWER_WIDTH });
    userSettingsAutomat.actions.setChatDrawerWidth(DEFAULT_DRAWER_WIDTH);
  };

  cleanupResizeListeners = () => {
    document.body.style.cursor = '';
    document.body.style.userSelect = '';
  };


  handleSelectConversation = (e) => {
    const id = Number(e.target.value);
    if (id) {
      chatAutomat.actions.selectConversation(id);
      this.focusInput(50);
    }
  };

  handleNewChat = () => {
    chatAutomat.actions.startDraft();
    this.focusInput(50);
  };

  handleDeleteConversation = async (e, convId) => {
    e?.stopPropagation();
    e?.preventDefault();
    if (!convId) return;
    try {
      await chatAutomat.actions.deleteConversation(convId);
    } catch (err) {
      console.error('[ChatDrawer] Failed to delete conversation:', err);
    } finally {
      this.focusInput(50);
    }
  };

  handleSend = async (e) => {
    e?.preventDefault();
    const rawText = this.state.inputText.trim();
    const attachments = this.state.stagedAttachments || [];
    const references = this.state.stagedReferences || [];

    if (
      (!rawText && attachments.length === 0 && references.length === 0) ||
      this.state.conversationState === 'busy' ||
      this.state.isSending
    ) {
      return;
    }

    let text = rawText;
    if (references.length > 0) {
      const refMarkdown = references
        .map((ref) => {
          const lineRef = ref.startLine
            ? (ref.startLine === ref.endLine ? `L${ref.startLine}` : `L${ref.startLine}-L${ref.endLine}`)
            : null;
          const lineLabel = ref.startLine
            ? (ref.startLine === ref.endLine ? `:${ref.startLine}` : `:${ref.startLine}-${ref.endLine}`)
            : '';
          const link =
            ref.isImage && !lineRef
              ? `![${ref.fileName}](${ref.path || ref.fileName})`
              : `[${ref.fileName}${lineLabel}](${ref.path || ref.fileName}${lineRef ? `#${lineRef}` : ''})`;

          if (ref.selectedText && ref.selectedText.trim()) {
            const ext = ref.fileName.split('.').pop() || '';
            return `${link}\n\`\`\`${ext}\n${ref.selectedText.trim()}\n\`\`\``;
          }
          return link;
        })
        .join('\n\n');

      text = text ? `${refMarkdown}\n\n${text}` : refMarkdown;
    }

    this.setState({
      inputText: '',
      stagedAttachments: [],
      stagedReferences: [],
      attachmentError: null,
    });

    try {
      await chatAutomat.actions.sendMessage(text, attachments);
    } catch {
      // Error is tracked in chatAutomat state (sendError)
    }
  };

  handleOpenFileDialog = () => {
    this.fileInputRef.current?.click();
  };

  handleFileSelect = (e) => {
    const files = e.target?.files;
    if (files && files.length > 0) {
      void this.handleFiles(Array.from(files));
    }
    if (e.target) {
      e.target.value = '';
    }
  };

  handleFiles = async (fileList) => {
    if (!fileList || fileList.length === 0) return;
    this.setState({ isProcessingFiles: true, attachmentError: null });

    const newAttachments = [];
    const errors = [];

    for (const file of fileList) {
      try {
        const att = await readFileAttachment(file);
        newAttachments.push(att);
      } catch (err) {
        errors.push(err.message || `Datei "${file.name}" konnte nicht verarbeitet werden.`);
      }
    }

    this.setState((prev) => ({
      stagedAttachments: [...prev.stagedAttachments, ...newAttachments],
      isProcessingFiles: false,
      attachmentError: errors.length > 0 ? errors.join(' ') : null,
    }));
    this.focusInput(50);
  };

  handleRemoveAttachment = (idOrIdx) => {
    this.setState((prev) => ({
      stagedAttachments: prev.stagedAttachments.filter((a, idx) => (a.id ? a.id !== idOrIdx : idx !== idOrIdx)),
    }));
  };

  handlePaste = (e) => {
    const items = e.clipboardData?.items;
    if (!items || items.length === 0) return;

    const files = [];
    for (let i = 0; i < items.length; i++) {
      const item = items[i];
      if (item.kind === 'file') {
        const file = item.getAsFile();
        if (file) files.push(file);
      }
    }

    if (files.length > 0) {
      e.preventDefault();
      void this.handleFiles(files);
    }
  };

  handleDragEnter = (e) => {
    e.preventDefault();
    e.stopPropagation();
    if (e.dataTransfer?.types?.includes('Files')) {
      this.setState({ isDraggingFiles: true });
    }
  };

  handleDragOver = (e) => {
    e.preventDefault();
    e.stopPropagation();
    if (!this.state.isDraggingFiles && e.dataTransfer?.types?.includes('Files')) {
      this.setState({ isDraggingFiles: true });
    }
  };

  handleDragLeave = (e) => {
    e.preventDefault();
    e.stopPropagation();
    if (e.currentTarget.contains(e.relatedTarget)) return;
    this.setState({ isDraggingFiles: false });
  };

  handleDrop = (e) => {
    e.preventDefault();
    e.stopPropagation();
    this.setState({ isDraggingFiles: false });
    const files = e.dataTransfer?.files;
    if (files && files.length > 0) {
      void this.handleFiles(Array.from(files));
    }
  };

  handleKeyDown = (e) => {
    if (e.key === 'Enter' && !e.shiftKey) {
      e.preventDefault();
      void this.handleSend();
    }
  };

  handleAnswerTool = async ({ tool_call_id, answer }) => {
    try {
      await chatAutomat.actions.sendToolResponse({ tool_call_id, answer });
    } catch (err) {
      console.error('[ChatDrawer] Failed to send tool response:', err);
    }
  };

  loadModelSettings = async () => {
    try {
      const data = await settingApi.list();
      const settings = data?.settings || [];
      const flagSetting = settings.find((s) => s.key === 'modelslugflag');
      const reasoningSetting = settings.find((s) => s.key === 'modelreasoning');
      const slugSetting = settings.find((s) => s.key === 'modelslug');
      this.setState({
        modelslugflag: flagSetting?.value ?? 'floor',
        modelreasoning: reasoningSetting?.value ?? 'medium',
        modelslug: slugSetting?.value ?? 'openai/gpt-6-luna',
      });
    } catch (err) {
      console.error('[ChatDrawer] Failed to load model settings:', err);
    }
  };

  handleToggleSettingsBar = () => {
    this.setState((prev) => ({ showSettingsBar: !prev.showSettingsBar }));
  };

  handleSetFlag = async (nextFlag) => {
    if (this.state.modelslugflag === nextFlag) return;
    const current = this.state.modelslugflag;
    this.setState({ modelslugflag: nextFlag });
    try {
      await settingApi.upsert('modelslugflag', { value: nextFlag });
    } catch (err) {
      console.error('[ChatDrawer] Failed to save modelslugflag:', err);
      this.setState({ modelslugflag: current });
    }
  };

  handleSetReasoning = async (nextReasoning) => {
    if (this.state.modelreasoning === nextReasoning) return;
    const current = this.state.modelreasoning;
    this.setState({ modelreasoning: nextReasoning });
    try {
      await settingApi.upsert('modelreasoning', { value: nextReasoning });
    } catch (err) {
      console.error('[ChatDrawer] Failed to save modelreasoning:', err);
      this.setState({ modelreasoning: current });
    }
  };

  handleModelslugChange = (e) => {
    this.setState({ modelslug: e.target.value });
  };

  handleModelslugBlur = async () => {
    const { modelslug } = this.state;
    const trimmed = (modelslug || '').trim();
    try {
      await settingApi.upsert('modelslug', { value: trimmed });
    } catch (err) {
      console.error('[ChatDrawer] Failed to save modelslug:', err);
    }
  };

  handleModelslugKeyDown = (e) => {
    if (e.key === 'Enter') {
      e.target.blur();
    }
  };

  getPendingAskUser = () => selectPendingAskUser(this.state);

  renderHeader() {
    const {
      conversations,
      selectedConversationId,
      loadingConversations,
      showSettingsBar,
      modelslugflag,
      modelreasoning,
      modelslug,
      isVfsOpen,
    } = this.state;

    return (
      <Box
        sx={{
          p: 2,
          borderBottom: 1,
          borderColor: 'divider',
          bgcolor: 'background.paper',
          display: 'flex',
          flexDirection: 'column',
          gap: 1.5,
        }}
      >
        <Box sx={{ display: 'flex', alignItems: 'center', justifyContent: 'space-between', minHeight: 34 }}>
          {showSettingsBar ? (
            /* Settings Bar Mode: Title goes away and reveals toggles */
            <Box sx={{ display: 'flex', alignItems: 'center', gap: 0.75, flex: 1, minWidth: 0, overflow: 'hidden' }}>
              <IconButton
                size="small"
                onClick={this.handleToggleSettingsBar}
                aria-label="Einstellungen schließen"
                sx={{
                  p: 0.5,
                  color: 'primary.main',
                  bgcolor: 'action.selected',
                  flexShrink: 0,
                }}
              >
                <TuneRoundedIcon sx={{ fontSize: 18 }} />
              </IconButton>

              {/* Group 1: Speed (floor, walk/standard "", run/nitro) */}
              <Box
                sx={{
                  display: 'inline-flex',
                  alignItems: 'center',
                  gap: 0.3,
                  bgcolor: (theme) => (theme.palette.mode === 'dark' ? 'rgba(255,255,255,0.06)' : 'rgba(0,0,0,0.05)'),
                  p: 0.3,
                  borderRadius: 2,
                  flexShrink: 0,
                }}
              >
                <IconButton
                  size="small"
                  onClick={() => this.handleSetFlag('floor')}
                  aria-label="Floor"
                  sx={{
                    p: 0.3,
                    width: 26,
                    height: 26,
                    borderRadius: 1.5,
                    bgcolor: modelslugflag === 'floor' ? 'primary.main' : 'transparent',
                    color: modelslugflag === 'floor' ? 'primary.contrastText' : 'text.secondary',
                    '&:hover': {
                      bgcolor: modelslugflag === 'floor' ? 'primary.dark' : 'action.selected',
                    },
                  }}
                >
                  <ElderlyRoundedIcon sx={{ fontSize: 17 }} />
                </IconButton>

                <IconButton
                  size="small"
                  onClick={() => this.handleSetFlag('')}
                  aria-label="Normal"
                  sx={{
                    p: 0.3,
                    width: 26,
                    height: 26,
                    borderRadius: 1.5,
                    bgcolor: modelslugflag === '' ? 'primary.main' : 'transparent',
                    color: modelslugflag === '' ? 'primary.contrastText' : 'text.secondary',
                    '&:hover': {
                      bgcolor: modelslugflag === '' ? 'primary.dark' : 'action.selected',
                    },
                  }}
                >
                  <DirectionsWalkRoundedIcon sx={{ fontSize: 17 }} />
                </IconButton>

                <IconButton
                  size="small"
                  onClick={() => this.handleSetFlag('nitro')}
                  aria-label="Nitro"
                  sx={{
                    p: 0.3,
                    width: 26,
                    height: 26,
                    borderRadius: 1.5,
                    bgcolor: modelslugflag === 'nitro' ? 'primary.main' : 'transparent',
                    color: modelslugflag === 'nitro' ? 'primary.contrastText' : 'text.secondary',
                    '&:hover': {
                      bgcolor: modelslugflag === 'nitro' ? 'primary.dark' : 'action.selected',
                    },
                  }}
                >
                  <DirectionsRunRoundedIcon sx={{ fontSize: 17 }} />
                </IconButton>
              </Box>

              <Divider orientation="vertical" flexItem sx={{ mx: 0.3, my: 0.5 }} />

              {/* Group 2: Reasoning (none, low, medium, max) */}
              <Box
                sx={{
                  display: 'inline-flex',
                  alignItems: 'center',
                  gap: 0.3,
                  bgcolor: (theme) => (theme.palette.mode === 'dark' ? 'rgba(255,255,255,0.06)' : 'rgba(0,0,0,0.05)'),
                  p: 0.3,
                  borderRadius: 2,
                  flexShrink: 0,
                }}
              >
                {/* none toggle (crossed out brain) */}
                <IconButton
                  size="small"
                  onClick={() => this.handleSetReasoning('none')}
                  aria-label="Reasoning None"
                  sx={{
                    p: 0.3,
                    width: 26,
                    height: 26,
                    borderRadius: 1.5,
                    bgcolor: modelreasoning === 'none' ? 'primary.main' : 'transparent',
                    color: modelreasoning === 'none' ? 'primary.contrastText' : 'text.secondary',
                    '&:hover': {
                      bgcolor: modelreasoning === 'none' ? 'primary.dark' : 'action.selected',
                    },
                  }}
                >
                  <Box sx={{ position: 'relative', display: 'inline-flex', alignItems: 'center', justifyContent: 'center' }}>
                    <PsychologyRoundedIcon sx={{ fontSize: 16 }} />
                    <Box
                      sx={{
                        position: 'absolute',
                        width: '125%',
                        height: '1.5px',
                        bgcolor: modelreasoning === 'none' ? 'primary.contrastText' : 'error.main',
                        transform: 'rotate(-45deg)',
                        borderRadius: 1,
                      }}
                    />
                  </Box>
                </IconButton>

                {/* low toggle (smallest brain) */}
                <IconButton
                  size="small"
                  onClick={() => this.handleSetReasoning('low')}
                  aria-label="Reasoning Low"
                  sx={{
                    p: 0.3,
                    width: 26,
                    height: 26,
                    borderRadius: 1.5,
                    bgcolor: modelreasoning === 'low' ? 'primary.main' : 'transparent',
                    color: modelreasoning === 'low' ? 'primary.contrastText' : 'text.secondary',
                    '&:hover': {
                      bgcolor: modelreasoning === 'low' ? 'primary.dark' : 'action.selected',
                    },
                  }}
                >
                  <PsychologyRoundedIcon sx={{ fontSize: 13 }} />
                </IconButton>

                {/* medium toggle (medium brain) */}
                <IconButton
                  size="small"
                  onClick={() => this.handleSetReasoning('medium')}
                  aria-label="Reasoning Medium"
                  sx={{
                    p: 0.3,
                    width: 26,
                    height: 26,
                    borderRadius: 1.5,
                    bgcolor: modelreasoning === 'medium' ? 'primary.main' : 'transparent',
                    color: modelreasoning === 'medium' ? 'primary.contrastText' : 'text.secondary',
                    '&:hover': {
                      bgcolor: modelreasoning === 'medium' ? 'primary.dark' : 'action.selected',
                    },
                  }}
                >
                  <PsychologyRoundedIcon sx={{ fontSize: 17 }} />
                </IconButton>

                {/* max toggle (big brain) */}
                <IconButton
                  size="small"
                  onClick={() => this.handleSetReasoning('high')}
                  aria-label="Reasoning Max"
                  sx={{
                    p: 0.3,
                    width: 26,
                    height: 26,
                    borderRadius: 1.5,
                    bgcolor: modelreasoning === 'high' ? 'primary.main' : 'transparent',
                    color: modelreasoning === 'high' ? 'primary.contrastText' : 'text.secondary',
                    '&:hover': {
                      bgcolor: modelreasoning === 'high' ? 'primary.dark' : 'action.selected',
                    },
                  }}
                >
                  <PsychologyRoundedIcon sx={{ fontSize: 22 }} />
                </IconButton>
              </Box>

              <Divider orientation="vertical" flexItem sx={{ mx: 0.3, my: 0.5 }} />

              {/* modelslug input */}
              <InputBase
                value={modelslug || ''}
                onChange={this.handleModelslugChange}
                onBlur={this.handleModelslugBlur}
                onKeyDown={this.handleModelslugKeyDown}
                placeholder="Modellslug"
                inputProps={{
                  spellCheck: false,
                  autoCorrect: 'off',
                  autoCapitalize: 'off',
                  'aria-label': 'Modellslug',
                }}
                sx={{
                  flex: 1,
                  minWidth: 80,
                  fontSize: '0.78rem',
                  fontFamily: 'monospace',
                  px: 0.8,
                  py: 0.2,
                  bgcolor: (theme) => (theme.palette.mode === 'dark' ? 'rgba(255,255,255,0.06)' : 'rgba(0,0,0,0.05)'),
                  borderRadius: 1.5,
                  border: '1px solid transparent',
                  '&:focus-within': {
                    borderColor: 'primary.main',
                    bgcolor: (theme) => (theme.palette.mode === 'dark' ? 'rgba(255,255,255,0.1)' : '#fff'),
                  },
                  '& input': {
                    p: 0,
                    overflow: 'hidden',
                    textOverflow: 'ellipsis',
                  },
                }}
              />
            </Box>
          ) : (
            /* Normal Mode: settings icon on the left end, title visible */
            <Box sx={{ display: 'flex', alignItems: 'center', gap: 1 }}>
              <IconButton
                size="small"
                onClick={this.handleToggleSettingsBar}
                aria-label="Modell-Einstellungen"
                sx={{
                  p: 0.5,
                  color: 'text.secondary',
                  '&:hover': { color: 'primary.main', bgcolor: 'action.hover' },
                }}
              >
                <TuneRoundedIcon sx={{ fontSize: 18 }} />
              </IconButton>
              <AutoAwesomeRoundedIcon sx={{ fontSize: 20, color: 'primary.main' }} />
              <Typography variant="subtitle1" fontWeight={700}>
                KI-Assistent
              </Typography>
            </Box>
          )}

          <Box sx={{ display: 'flex', alignItems: 'center', gap: 0.5, ml: 1, flexShrink: 0 }}>
            <Tooltip title={isVfsOpen ? 'Dateien schließen' : 'Dateien parallel öffnen'}>
              <IconButton
                size="small"
                onClick={() => vfsAutomat.actions.toggleVfs()}
                aria-label="Dateien"
                sx={{
                  p: 0.5,
                  color: isVfsOpen ? 'primary.main' : 'text.secondary',
                  bgcolor: isVfsOpen ? 'action.selected' : 'transparent',
                  borderRadius: 1.5,
                  border: '1px solid',
                  borderColor: isVfsOpen ? 'primary.main' : 'transparent',
                  '&:hover': {
                    color: 'primary.main',
                    bgcolor: 'action.hover',
                  },
                }}
              >
                <FolderOpenRoundedIcon sx={{ fontSize: 19 }} />
              </IconButton>
            </Tooltip>

            <IconButton size="small" onClick={this.handleClose} aria-label="Chat schließen" sx={{ p: 0.5 }}>
              <CloseRoundedIcon fontSize="small" />
            </IconButton>
          </Box>
        </Box>


        {/* Conversation Selector Bar */}
        {conversations.length > 0 && (
          <Box sx={{ display: 'flex', alignItems: 'center', gap: 1 }}>
            <FormControl fullWidth size="small">
              <InputLabel id="chat-conversation-label">Konversation</InputLabel>
              <Select
                labelId="chat-conversation-label"
                value={selectedConversationId || ''}
                label="Konversation"
                onChange={this.handleSelectConversation}
                disabled={loadingConversations || conversations.length === 0}
                sx={{ borderRadius: 2 }}
                renderValue={(selectedId) => {
                  const conv = conversations.find((c) => c.id === selectedId);
                  if (!conv) return '';
                  return (
                    <Box sx={{ display: 'flex', alignItems: 'center', gap: 1, overflow: 'hidden' }}>
                      <Typography variant="body2" fontWeight={600} noWrap>
                        #{conv.id}
                      </Typography>
                      <Typography variant="caption" color="text.secondary" noWrap>
                        {conv.model || 'Standard'}
                      </Typography>
                    </Box>
                  );
                }}
              >
                {conversations.map((c) => (
                  <MenuItem key={c.id} value={c.id}>
                    <Box sx={{ display: 'flex', alignItems: 'center', gap: 1, width: '100%', overflow: 'hidden' }}>
                      <Typography variant="body2" fontWeight={600} noWrap>
                        #{c.id}
                      </Typography>
                      <Typography variant="caption" color="text.secondary" noWrap sx={{ flexGrow: 1 }}>
                        {c.model || 'Standard'}
                      </Typography>
                    </Box>
                  </MenuItem>
                ))}
              </Select>
            </FormControl>

            <IconButton
              size="small"
              color="error"
              disabled={!selectedConversationId}
              onClick={(e) => this.handleDeleteConversation(e, selectedConversationId)}
              aria-label="Konversation löschen"
              sx={{
                borderRadius: 2,
                border: 1,
                borderColor: 'divider',
                p: 0.9,
                flexShrink: 0,
              }}
            >
              <DeleteOutlineRoundedIcon fontSize="small" />
            </IconButton>

            <IconButton
              size="small"
              color="primary"
              disabled={!selectedConversationId}
              onClick={this.handleNewChat}
              aria-label="Neuer Chat"
              sx={{
                borderRadius: 2,
                border: 1,
                borderColor: 'divider',
                p: 0.9,
                flexShrink: 0,
              }}
            >
              <AddRoundedIcon fontSize="small" />
            </IconButton>
          </Box>
        )}
      </Box>
    );
  }

  renderBody() {
    const {
      conversations,
      selectedConversationId,
      draftConversation,
      conversationState,
      messages,
      streamingText,
      loadingConversations,
      model,
    } = this.state;

    if (loadingConversations && conversations.length === 0) {
      return (
        <Box sx={{ flexGrow: 1, display: 'flex', flexDirection: 'column', alignItems: 'center', justifyContent: 'center', p: 3, gap: 2 }}>
          <CircularProgress size={32} />
          <Typography variant="body2" color="text.secondary">
            Lade Konversationen…
          </Typography>
        </Box>
      );
    }

    if (conversations.length === 0 && !draftConversation) {
      return (
        <Box
          sx={{
            flexGrow: 1,
            display: 'flex',
            flexDirection: 'column',
            alignItems: 'center',
            justifyContent: 'center',
            p: 4,
            textAlign: 'center',
            gap: 2,
          }}
        >
          <AutoAwesomeRoundedIcon sx={{ fontSize: 44, color: 'primary.main', opacity: 0.85 }} />
          <Typography variant="h6" fontWeight={700}>
            Willkommen im Chat
          </Typography>
          <Typography variant="body2" color="text.secondary" sx={{ maxWidth: 280 }}>
            Starte eine Unterhaltung mit dem KI-Modell, um Fragen zu stellen oder Daten abzufragen.
          </Typography>
          <Button
            variant="contained"
            startIcon={<AddRoundedIcon />}
            onClick={this.handleNewChat}
            sx={{ borderRadius: 2, mt: 1 }}
          >
            Neuen Chat starten
          </Button>
        </Box>
      );
    }

    const pendingAsk = this.getPendingAskUser();

    return (
      <Box sx={{ flexGrow: 1, display: 'flex', flexDirection: 'column', minHeight: 0, overflow: 'hidden' }}>
        {messages.length === 0 ? (
          <Box sx={{ flexGrow: 1 }} />
        ) : (
          <ChatFlowList
            messages={
              streamingText && (!this.state.activeTurns || this.state.activeTurns.length === 0)
                ? [
                    ...messages,
                    {
                      id: 'streaming',
                      conversation_id: selectedConversationId,
                      role: 'assistant',
                      message: streamingText,
                      streaming: true,
                    },
                  ]
                : messages
            }
            activeTurns={this.state.activeTurns}
            conversationState={conversationState}
            model={model}
          />
        )}

        {pendingAsk && (
          <AskUserPrompt
            askData={pendingAsk}
            onAnswer={this.handleAnswerTool}
            disabled={this.state.isSending}
          />
        )}
      </Box>
    );
  }

  renderFooter() {
    const {
      conversationState,
      isSending,
      selectedConversationId,
      draftConversation,
      inputText,
      isInputFocused,
      sendError,
      stagedAttachments,
      stagedReferences,
      isProcessingFiles,
      isDraggingFiles,
      attachmentError,
    } = this.state;

    const pendingAsk = this.getPendingAskUser();
    const isBusy = conversationState === 'busy';
    const isWorking = isBusy || isSending;
    const canChat = (Boolean(selectedConversationId) || draftConversation) && !pendingAsk;
    const canSend =
      !isWorking &&
      canChat &&
      (Boolean(inputText.trim()) || stagedAttachments.length > 0 || stagedReferences.length > 0);

    return (
      <Box
        component="form"
        onSubmit={this.handleSend}
        onDragEnter={this.handleDragEnter}
        onDragOver={this.handleDragOver}
        onDragLeave={this.handleDragLeave}
        onDrop={this.handleDrop}
        sx={{
          p: 2,
          borderTop: 1,
          borderColor: isDraggingFiles ? 'primary.main' : 'divider',
          bgcolor: isDraggingFiles ? 'action.hover' : 'background.paper',
          transition: 'border-color 0.15s, background-color 0.15s',
          display: 'flex',
          flexDirection: 'column',
          gap: 1,
          position: 'relative',
        }}
      >
        {sendError && (
          <Box
            sx={{
              p: 1,
              borderRadius: 1.5,
              bgcolor: 'error.light',
              color: 'error.contrastText',
              fontSize: '0.75rem',
              display: 'flex',
              justifyContent: 'space-between',
              alignItems: 'center',
            }}
          >
            <Typography variant="caption">{sendError}</Typography>
            <IconButton
              size="small"
              onClick={() => chatAutomat.setState({ sendError: null })}
              sx={{ color: 'inherit', p: 0.2 }}
            >
              <CloseRoundedIcon sx={{ fontSize: 14 }} />
            </IconButton>
          </Box>
        )}

        {attachmentError && (
          <Box
            sx={{
              p: 1,
              borderRadius: 1.5,
              bgcolor: 'warning.light',
              color: 'warning.contrastText',
              fontSize: '0.75rem',
              display: 'flex',
              justifyContent: 'space-between',
              alignItems: 'center',
            }}
          >
            <Typography variant="caption">{attachmentError}</Typography>
            <IconButton
              size="small"
              onClick={() => this.setState({ attachmentError: null })}
              sx={{ color: 'inherit', p: 0.2 }}
            >
              <CloseRoundedIcon sx={{ fontSize: 14 }} />
            </IconButton>
          </Box>
        )}

        {/* Staged attachments tray */}
        <ChatStagedAttachmentsTray
          attachments={stagedAttachments}
          onRemove={this.handleRemoveAttachment}
        />

        {isProcessingFiles && (
          <Box sx={{ display: 'flex', alignItems: 'center', gap: 1, py: 0.5, px: 1 }}>
            <CircularProgress size={14} thickness={5} />
            <Typography variant="caption" sx={{ color: 'text.secondary', fontSize: '0.72rem' }}>
              Dateien werden eingelesen…
            </Typography>
          </Box>
        )}

        {isDraggingFiles && (
          <Box
            sx={{
              p: 1.5,
              border: '2px dashed',
              borderColor: 'primary.main',
              borderRadius: 2,
              textAlign: 'center',
              bgcolor: 'action.selected',
              color: 'primary.main',
              fontWeight: 500,
              fontSize: '0.85rem',
            }}
          >
            Dateien hier ablegen (Bilder, PDFs, CSV, Text, XML, HTML)
          </Box>
        )}

        <Box sx={{ display: 'flex', alignItems: 'flex-end', gap: 1 }}>
          {/* Attachment Icon Button */}
          <Tooltip title="Dateien anhängen (Bilder, PDFs, CSV, Text, XML, HTML)">
            <span>
              <IconButton
                size="small"
                onClick={this.handleOpenFileDialog}
                disabled={!canChat || isWorking}
                aria-label="Dateien anhängen"
                sx={{
                  width: 40,
                  height: 40,
                  borderRadius: 2.5,
                  color: stagedAttachments.length > 0 ? 'primary.main' : 'text.secondary',
                  bgcolor: stagedAttachments.length > 0 ? 'action.selected' : 'transparent',
                  border: '1px solid',
                  borderColor: stagedAttachments.length > 0 ? 'primary.main' : 'transparent',
                  flexShrink: 0,
                  '&:hover': {
                    bgcolor: 'action.hover',
                    color: 'primary.main',
                  },
                }}
              >
                <Badge badgeContent={stagedAttachments.length} color="primary">
                  <AttachFileRoundedIcon sx={{ fontSize: 22 }} />
                </Badge>
              </IconButton>
            </span>
          </Tooltip>

          {/* Hidden File Input */}
          <input
            ref={this.fileInputRef}
            type="file"
            multiple
            accept={ACCEPT_STRING}
            onChange={this.handleFileSelect}
            style={{ display: 'none' }}
          />

          {/* Unified Copilot-style input container with context reference pills */}
          <Box
            onClick={() => this.focusInput(0)}
            sx={{
              flex: 1,
              minWidth: 0,
              display: 'flex',
              flexDirection: 'column',
              bgcolor: 'background.paper',
              border: '1px solid',
              borderColor: isInputFocused ? 'primary.main' : 'divider',
              boxShadow: isInputFocused ? (theme) => `0 0 0 1px ${theme.palette.primary.main}` : 'none',
              borderRadius: 2.5,
              p: 0.75,
              gap: 0.5,
              cursor: 'text',
              transition: 'border-color 0.15s, box-shadow 0.15s',
              minHeight: 40,
              boxSizing: 'border-box',
            }}
          >
            {stagedReferences.length > 0 && (
              <Box
                sx={{
                  display: 'flex',
                  flexWrap: 'wrap',
                  gap: 0.6,
                  alignItems: 'center',
                  mb: 0.25,
                }}
              >
                {stagedReferences.map((ref) => (
                  <Box
                    key={ref.id}
                    onClick={(e) => {
                      e.stopPropagation();
                      vfsAutomat.actions.openVfs();
                      vfsAutomat.actions.selectFile(ref.fileName);
                    }}
                    sx={{
                      display: 'inline-flex',
                      alignItems: 'center',
                      gap: 0.6,
                      py: 0.2,
                      pl: 0.7,
                      pr: 0.4,
                      borderRadius: 1.5,
                      bgcolor: (theme) =>
                        theme.palette.mode === 'dark'
                          ? 'rgba(255, 255, 255, 0.08)'
                          : 'rgba(0, 0, 0, 0.05)',
                      border: '1px solid',
                      borderColor: (theme) =>
                        theme.palette.mode === 'dark'
                          ? 'rgba(255, 255, 255, 0.12)'
                          : 'rgba(0, 0, 0, 0.1)',
                      color: 'text.primary',
                      fontSize: '0.75rem',
                      lineHeight: 1.2,
                      userSelect: 'none',
                      cursor: 'pointer',
                      transition: 'all 0.15s ease',
                      '&:hover': {
                        bgcolor: (theme) =>
                          theme.palette.mode === 'dark'
                            ? 'rgba(255, 255, 255, 0.14)'
                            : 'rgba(0, 0, 0, 0.09)',
                        borderColor: 'primary.light',
                      },
                    }}
                  >
                    <VfsFileIcon fileName={ref.fileName} sx={{ fontSize: 14 }} />
                    <Typography
                      component="span"
                      sx={{
                        fontFamily: "'SFMono-Regular', Consolas, 'Liberation Mono', Menlo, Courier, monospace",
                        fontSize: '0.74rem',
                        fontWeight: 600,
                        letterSpacing: '-0.2px',
                        display: 'inline-flex',
                        alignItems: 'center',
                      }}
                    >
                      {ref.fileName}
                      {ref.startLine && (
                        <Box
                          component="span"
                          sx={{
                            color: 'primary.main',
                            fontWeight: 700,
                            ml: 0.3,
                          }}
                        >
                          :{ref.startLine === ref.endLine ? ref.startLine : `${ref.startLine}-${ref.endLine}`}
                        </Box>
                      )}
                    </Typography>
                    <IconButton
                      size="small"
                      onClick={(e) => {
                        e.stopPropagation();
                        this.handleRemoveReference(ref.id);
                      }}
                      aria-label="Referenz entfernen"
                      sx={{
                        p: 0.2,
                        ml: 0.1,
                        color: 'text.secondary',
                        '&:hover': {
                          color: 'error.main',
                          bgcolor: 'action.hover',
                        },
                      }}
                    >
                      <CloseRoundedIcon sx={{ fontSize: 13 }} />
                    </IconButton>
                  </Box>
                ))}
              </Box>
            )}

            <InputBase
              inputRef={this.inputRef}
              multiline
              minRows={1}
              maxRows={5}
              fullWidth
              value={inputText}
              onChange={(e) => this.setState({ inputText: e.target.value })}
              onKeyDown={this.handleKeyDown}
              onPaste={this.handlePaste}
              onFocus={() => this.setState({ isInputFocused: true })}
              onBlur={() => this.setState({ isInputFocused: false })}
              disabled={!canChat}
              placeholder={
                pendingAsk
                  ? 'Bitte Frage oben beantworten…'
                  : stagedAttachments.length > 0
                    ? 'Nachricht hinzufügen oder direkt absenden…'
                    : undefined
              }
              sx={{
                px: 0.5,
                py: 0.1,
                fontSize: '0.875rem',
                lineHeight: 1.45,
                '& .MuiInputBase-input': {
                  p: 0,
                },
              }}
            />
          </Box>

          <IconButton
            type="submit"
            color="primary"
            disabled={!canSend}
            title={
              isWorking
                ? 'Modell antwortet gerade…'
                : 'Senden (Enter)'
            }
            sx={{
              bgcolor: isWorking ? 'action.hover' : 'primary.main',
              color: isWorking ? 'warning.main' : 'primary.contrastText',
              width: 40,
              height: 40,
              borderRadius: 2.5,
              flexShrink: 0,
              '&:hover': {
                bgcolor: 'primary.dark',
              },
              '&.Mui-disabled': {
                bgcolor: isWorking ? 'action.hover' : 'primary.main',
                color: isWorking ? 'warning.main' : 'primary.contrastText',
                cursor: 'default',
              },
            }}
          >
            {isWorking ? (
              <CircularProgress size={18} color="inherit" thickness={4.5} />
            ) : (
              <SendRoundedIcon sx={{ fontSize: 20 }} />
            )}
          </IconButton>
        </Box>
      </Box>
    );
  }

  render() {
    const { isOpen, drawerWidth, isResizing, isVfsOpen, vfsWidth } = this.state;
    const totalWidth = isVfsOpen ? drawerWidth + vfsWidth : drawerWidth;

    return (
      <>
        <Drawer
          anchor="right"
          open={isOpen}
          onClose={this.handleClose}
          sx={(theme) => ({
            zIndex: theme.zIndex.drawer + 2,
            '& .MuiDrawer-paper': {
              width: { xs: '100vw', sm: `${totalWidth}px` },
              maxWidth: '100vw',
              display: 'flex',
              flexDirection: 'row',
              boxShadow: SHADOW_DRAWER,
              position: 'fixed',
              overflow: 'visible',
              transition: isResizing ? 'none !important' : undefined,
            },
          })}
          slotProps={{
            transition: {
              onEntered: () => this.focusInput(20),
            },
            paper: {
              sx: {
                width: { xs: '100vw', sm: `${totalWidth}px` },
                maxWidth: '100vw',
                display: 'flex',
                flexDirection: 'row',
                boxShadow: SHADOW_DRAWER,
                position: 'fixed',
                overflow: 'visible',
                transition: isResizing ? 'none !important' : undefined,
              },
            },
          }}
        >
          {/* Draggable Resizer Handle */}
          <Box
            onPointerDown={this.handleResizeStart}
            onMouseDown={this.handleResizeStart}
            onTouchStart={this.handleResizeStart}
            onDoubleClick={this.handleResizeDoubleClick}
            title="Ziehen zum Anpassen der Breite • Doppelklick zum Zurücksetzen"
            sx={{
              position: 'absolute',
              top: 0,
              bottom: 0,
              left: 0,
              width: 16,
              cursor: 'col-resize',
              zIndex: 9999,
              display: { xs: 'none', sm: 'flex' },
              alignItems: 'center',
              justifyContent: 'center',
              touchAction: 'none',
              userSelect: 'none',
              '&:hover .drawer-resizer-line, &:active .drawer-resizer-line': {
                bgcolor: 'primary.main',
                height: 56,
                width: 4,
                opacity: 1,
                boxShadow: `0 0 10px ${BLUE_GLOW}`,
              },
            }}
          >
            <Box
              className="drawer-resizer-line"
              sx={{
                width: isResizing ? 4 : 3,
                height: isResizing ? 56 : 36,
                borderRadius: 2,
                bgcolor: isResizing ? 'primary.main' : 'divider',
                opacity: isResizing ? 1 : 0.6,
                transition: 'background-color 0.15s, height 0.15s, width 0.15s, opacity 0.15s, box-shadow 0.15s',
                boxShadow: isResizing ? `0 0 10px ${BLUE_GLOW}` : 'none',
              }}
            />
          </Box>

          {/* Left: VFS Filesystem Editor Panel (parallel to chat) */}
          {isVfsOpen && (
            <Box
              sx={{
                width: { xs: '100%', sm: `${vfsWidth}px` },
                minWidth: { sm: 340 },
                maxWidth: { sm: 'calc(100vw - 320px)' },
                height: '100%',
                flexShrink: 0,
                display: 'flex',
                flexDirection: 'column',
                overflow: 'hidden',
              }}
            >
              <VfsEditorPanel
                onInsertToChat={this.handleInsertToChat}
                onMentionReference={this.handleMentionReference}
              />
            </Box>
          )}

          {/* Vertical Split Resizer between VFS and Chat (0px width so no layout shift or grey bar) */}
          {isVfsOpen && (
            <Box
              onPointerDown={this.handleVfsResizerStart}
              onMouseDown={this.handleVfsResizerStart}
              sx={{
                width: 0,
                position: 'relative',
                flexShrink: 0,
                zIndex: 10,
                display: { xs: 'none', sm: 'flex' },
                alignItems: 'center',
                justifyContent: 'center',
                cursor: 'col-resize',
                touchAction: 'none',
                userSelect: 'none',
                '&:hover .vfs-resizer-line, &:active .vfs-resizer-line': {
                  bgcolor: 'primary.main',
                  opacity: 1,
                  height: 48,
                  width: 4,
                  boxShadow: `0 0 8px ${BLUE_GLOW}`,
                },
              }}
            >
              {/* Invisible wide hit area (16px wide, centered on the 1px border) */}
              <Box
                sx={{
                  position: 'absolute',
                  top: 0,
                  bottom: 0,
                  left: -8,
                  width: 16,
                  cursor: 'col-resize',
                }}
              />
              {/* Visual handle indicator on hover / active */}
              <Box
                className="vfs-resizer-line"
                sx={{
                  position: 'absolute',
                  width: 2,
                  height: 32,
                  borderRadius: 1,
                  bgcolor: 'divider',
                  opacity: 0.5,
                  transition: 'background-color 0.15s, height 0.15s, width 0.15s, opacity 0.15s, box-shadow 0.15s',
                  pointerEvents: 'none',
                }}
              />
            </Box>
          )}

          {/* Right: Chat Panel */}
          <Box
            sx={{
              width: isVfsOpen ? { xs: '100%', sm: `${drawerWidth}px` } : '100%',
              flexGrow: 1,
              minWidth: { sm: 320 },
              display: isVfsOpen ? { xs: 'none', sm: 'flex' } : 'flex',
              flexDirection: 'column',
              height: '100%',
              overflow: 'hidden',
              bgcolor: 'background.paper',
            }}
          >
            {this.renderHeader()}
            {this.renderBody()}
            {this.renderFooter()}
          </Box>
        </Drawer>
      </>
    );
  }

}