WeLearn-Go

自动填写 WeLearn 练习答案,支持小错误生成、自动提交和批量任务执行!

您需要先安裝使用者腳本管理器擴展,如 TampermonkeyGreasemonkeyViolentmonkey 之後才能安裝該腳本。

You will need to install an extension such as Tampermonkey to install this script.

您需要先安裝使用者腳本管理器擴充功能,如 TampermonkeyViolentmonkey 後才能安裝該腳本。

您需要先安裝使用者腳本管理器擴充功能,如 TampermonkeyUserscripts 後才能安裝該腳本。

你需要先安裝一款使用者腳本管理器擴展,比如 Tampermonkey,才能安裝此腳本

您需要先安裝使用者腳本管理器擴充功能後才能安裝該腳本。

(我已經安裝了使用者腳本管理器,讓我安裝!)

你需要先安裝一款使用者樣式管理器擴展,比如 Stylus,才能安裝此樣式

你需要先安裝一款使用者樣式管理器擴展,比如 Stylus,才能安裝此樣式

你需要先安裝一款使用者樣式管理器擴展,比如 Stylus,才能安裝此樣式

你需要先安裝一款使用者樣式管理器擴展後才能安裝此樣式

你需要先安裝一款使用者樣式管理器擴展後才能安裝此樣式

你需要先安裝一款使用者樣式管理器擴展後才能安裝此樣式

(我已經安裝了使用者樣式管理器,讓我安裝!)

// ==UserScript==
// @name         WeLearn-Go
// @namespace    https://github.com/noxsk/WeLearn-Go
// @supportURL   https://github.com/noxsk/WeLearn-Go/issues
// @version      0.9.9
// @description  自动填写 WeLearn 练习答案,支持小错误生成、自动提交和批量任务执行!
// @author       Noxsk
// @match        https://welearn.sflep.com/*
// @match        http://welearn.sflep.com/*
// @match        https://centercourseware.sflep.com/*
// @match        http://centercourseware.sflep.com/*
// @match        https://*.sflep.com/*
// @run-at       document-end
// @grant        GM_addStyle
// @grant        GM_info
// ==/UserScript==

(function () {
  'use strict';

  // ==================== 配置常量 ====================
  // 从 UserScript 元数据获取版本号(避免重复定义)
  const VERSION = (typeof GM_info !== 'undefined' && GM_info.script?.version) || '0.0.0';
  const SUBMIT_DELAY_MS = 300;              // 提交前的延迟时间(毫秒)
  const PANEL_MIN_WIDTH = 340;              // 面板最小宽度
  const PANEL_MIN_HEIGHT = 180;             // 面板最小高度
  const PANEL_MAX_WIDTH = 540;              // 面板最大宽度
  const PANEL_MAX_HEIGHT = 460;             // 面板最大高度
  const PANEL_DEFAULT_WIDTH = 340;          // 面板默认宽度
  const PANEL_DEFAULT_HEIGHT = 280;         // 面板默认高度
  const MINIMIZED_PANEL_SIZE = 42;          // 最小化时的面板尺寸
  const PANEL_STATE_KEY = 'welearn_panel_state';        // 面板状态存储键
  const ONBOARDING_STATE_KEY = 'welearn_onboarding_state';  // 引导状态存储键
  const ERROR_STATS_KEY = 'welearn_error_stats';            // 错误统计存储键
  const ERROR_WEIGHTS_KEY = 'welearn_error_weights';        // 错误权重配置存储键
  const MAX_ERRORS_PER_PAGE = 2;            // 每页最多添加的小错误数量
  // 默认错误数量百分比配置:0个(50%) vs 1个(35%) vs 2个(15%)
  const DEFAULT_ERROR_WEIGHTS = { w0: 50, w1: 35, w2: 15 };
  const GROUP_WORK_PATTERN = /group\s*work/i;  // Group Work 匹配模式
  const DONATE_IMAGE_URL = 'https://ossimg.yzitc.com/2025/12/03/eb461afdde7b3.png';  // 微信赞赏码图片地址
  const DONATE_IMAGE_CACHE_KEY = 'welearn_donate_image_cache';  // 赞赏码图片缓存键
  const BATCH_COMPLETED_KEY = 'welearn_batch_completed';  // 批量任务已完成记录存储键
  const BATCH_MODE_KEY = 'welearn_batch_mode';  // 批量模式状态存储键
  const COURSE_DIRECTORY_CACHE_KEY = 'welearn_course_directory_cache';  // 课程目录缓存键
  const BATCH_TASKS_CACHE_KEY = 'welearn_batch_tasks_cache';  // 批量任务选择缓存键
  const DURATION_MODE_KEY = 'welearn_duration_mode';  // 刷时长模式存储键
  const UPDATE_CHECK_URL = 'https://raw.githubusercontent.com/noxsk/WeLearn-Go/refs/heads/main/WeLearn-Go.user.js';  // 版本检查地址
  const UPDATE_CHECK_CACHE_KEY = 'welearn_update_check';  // 版本检查缓存键
  const UPDATE_CHECK_INTERVAL = 1 * 60 * 60 * 1000;  // 版本检查间隔1小时
  
  // 刷时长模式配置
  const DURATION_MODES = {
    off: {
      name: '关闭',
      baseTime: 0,
      perQuestionTime: 0,
      maxTime: 0,
      intervalTime: 0
    },
    fast: {
      name: '快速',
      baseTime: 30 * 1000,        // 基础 30 秒
      perQuestionTime: 5 * 1000,  // 每题 5 秒
      maxTime: 60 * 1000,         // 最大 60 秒
      intervalTime: 15 * 1000     // 心跳间隔 15 秒
    },
    standard: {
      name: '标准',
      baseTime: 60 * 1000,        // 基础 60 秒
      perQuestionTime: 10 * 1000, // 每题 10 秒
      maxTime: 120 * 1000,        // 最大 120 秒
      intervalTime: 30 * 1000     // 心跳间隔 30 秒
    }
  };

  // ==================== 全局状态变量 ====================
  let lastKnownUrl = location.href;         // 记录上次的 URL,用于检测页面切换
  let groupWorkDetected = false;            // 是否检测到 Group Work
  let groupWorkNoticeShown = false;         // 是否已显示 Group Work 提示
  let openEndedExerciseShown = false;       // 是否已显示开放式练习提示
  let donateImageDataUrl = null;            // 缓存的赞赏码图片 Data URL
  let batchModeActive = false;              // 批量模式是否激活
  let batchTaskQueue = [];                  // 批量任务队列
  let currentBatchTask = null;              // 当前正在处理的批量任务
  let selectedBatchTasks = [];              // 用户选择的待执行任务
  let selectedCourseName = '';              // 选择任务时的课程名称
  let latestVersion = null;                 // 最新版本号
  
  /** 判断是否为 WeLearn 相关域名 */
  const isWeLearnHost = () => {
    const host = location.hostname;
    return host.includes('welearn.sflep.com') || 
           host.includes('centercourseware.sflep.com') ||
           host.endsWith('.sflep.com');
  };
  
  /** 判断当前是否在 iframe 中运行 */
  const isInIframe = () => {
    try {
      return window.self !== window.top;
    } catch (e) {
      return true; // 跨域时无法访问 top,说明在 iframe 中
    }
  };
  
  const getAccessibleDocuments = () => {
    const docs = [document];
    document.querySelectorAll('iframe').forEach((frame) => {
      try {
        if (frame.contentDocument) docs.push(frame.contentDocument);
      } catch (error) {
        /* Ignore cross-origin frames */
      }
    });
    return docs;
  };

  /** 检查页面是否包含练习元素 */
  const hasExerciseElements = () =>
    getAccessibleDocuments().some((doc) =>
      doc.querySelector(
        '[data-controltype="pagecontrol"], [data-controltype="filling"], [data-controltype="fillinglong"], [data-controltype="choice"], [data-controltype="submit"], et-item, et-song, et-toggle, et-blank, .lrc, .dialog, .question-content, .exercise-content, .subjective, iframe',
      ),
    );

  /** 判断当前是否为 WeLearn 练习页面 */
  const isWeLearnPage = () => isWeLearnHost() && hasExerciseElements();

  /** 分割答案字符串(支持多种分隔符:/、|、;、,、、) */
  const splitSolutions = (value) =>
    value
      .split(/[\/|;,、]/)
      .map((item) => item.trim())
      .filter(Boolean);

  /** 标准化文本(去空格、转大写,用于答案比对) */
  const normalizeText = (text) => (text ?? '').trim().toUpperCase();

  /**
   * 格式化答案文本
   * @param {string} text - 原始文本
   * @param {Object} options - 配置选项
   * @param {boolean} options.collapseLines - 是否合并多行为单行(用于 Group Work)
   */
  const formatSolutionText = (text = '', { collapseLines = false } = {}) => {
    if (collapseLines) {
      return text
        .split(/\r?\n/)
        .map((line) => line.trim())
        .filter(Boolean)
        .join(' ')
        .trim();
    }

    const lines = text.split(/\r?\n/);
    const nonEmptyLines = lines.filter((line) => line.trim().length > 0);
    if (!nonEmptyLines.length) return text.trim();

    const baseIndent = nonEmptyLines.reduce((indent, line) => {
      const match = line.match(/^(\s*)/);
      const length = match ? match[1].length : 0;
      return indent === null ? length : Math.min(indent, length);
    }, null);

    return lines
      .map((line) => {
        if (!line.trim()) return '';
        const trimmedIndentLine = baseIndent ? line.slice(baseIndent) : line;
        return `  ${trimmedIndentLine.trimEnd()}`;
      })
      .join('\n')
      .trim();
  };

  /** 生成指定范围内的随机整数 */
  const randomInt = (min, max) => Math.floor(Math.random() * (max - min + 1)) + min;

  /**
   * 带权重的随机选择
   * @param {Array<{value: any, weight: number}>} options - 选项数组,每个选项包含值和权重
   * @returns {any} 根据权重随机选中的值
   */
  const weightedRandom = (options) => {
    const totalWeight = options.reduce((sum, opt) => sum + opt.weight, 0);
    let random = Math.random() * totalWeight;
    
    for (const { value, weight } of options) {
      random -= weight;
      if (random <= 0) return value;
    }
    
    return options[options.length - 1].value;
  };

  // ==================== 错误统计管理 ====================

  /** 加载错误权重配置 */
  const loadErrorWeights = () => {
    try {
      const raw = localStorage.getItem(ERROR_WEIGHTS_KEY);
      return raw ? JSON.parse(raw) : { ...DEFAULT_ERROR_WEIGHTS };
    } catch (error) {
      console.warn('WeLearn autofill: failed to load error weights', error);
      return { ...DEFAULT_ERROR_WEIGHTS };
    }
  };

  /** 保存错误权重配置 */
  const saveErrorWeights = (weights) => {
    try {
      localStorage.setItem(ERROR_WEIGHTS_KEY, JSON.stringify(weights));
    } catch (error) {
      console.warn('WeLearn autofill: failed to save error weights', error);
    }
  };

  /** 获取当前错误权重数组(用于 weightedRandom) */
  const getErrorCountWeights = () => {
    const w = loadErrorWeights();
    return [
      { value: 0, weight: w.w0 },
      { value: 1, weight: w.w1 },
      { value: 2, weight: w.w2 },
    ];
  };

  /** 加载错误统计数据 */
  const loadErrorStats = () => {
    try {
      const raw = localStorage.getItem(ERROR_STATS_KEY);
      return raw ? JSON.parse(raw) : { count0: 0, count1: 0, count2: 0 };
    } catch (error) {
      console.warn('WeLearn autofill: failed to load error stats', error);
      return { count0: 0, count1: 0, count2: 0 };
    }
  };

  /** 保存错误统计数据 */
  const saveErrorStats = (stats) => {
    try {
      localStorage.setItem(ERROR_STATS_KEY, JSON.stringify(stats));
    } catch (error) {
      console.warn('WeLearn autofill: failed to save error stats', error);
    }
  };

  /** 更新错误统计并刷新显示 */
  const updateErrorStats = (errorCount) => {
    const stats = loadErrorStats();
    if (errorCount === 0) stats.count0++;
    else if (errorCount === 1) stats.count1++;
    else if (errorCount === 2) stats.count2++;
    saveErrorStats(stats);
    refreshErrorStatsDisplay();
    return stats;
  };

  /** 清空错误统计 */
  const clearErrorStats = () => {
    saveErrorStats({ count0: 0, count1: 0, count2: 0 });
    refreshErrorStatsDisplay();
  };

  /** 刷新面板上的统计显示 */
  const refreshErrorStatsDisplay = () => {
    const statsEl = document.querySelector('.welearn-error-stats');
    if (!statsEl) return;
    const stats = loadErrorStats();
    const total = stats.count0 + stats.count1 + stats.count2;
    if (total === 0) {
      statsEl.innerHTML = '统计:暂无数据';
    } else {
      const pct0 = ((stats.count0 / total) * 100).toFixed(0);
      const pct1 = ((stats.count1 / total) * 100).toFixed(0);
      const pct2 = ((stats.count2 / total) * 100).toFixed(0);
      statsEl.innerHTML = `统计:<b>${stats.count0}</b> <b>${stats.count1}</b> <b>${stats.count2}</b> (${pct0}%/${pct1}%/${pct2}%)`;
    }
  };

  // ==================== 刷时长模式管理 ====================

  /** 加载刷时长模式配置 */
  const loadDurationMode = () => {
    try {
      const mode = localStorage.getItem(DURATION_MODE_KEY);
      return (mode && DURATION_MODES[mode]) ? mode : 'standard';
    } catch (error) {
      console.warn('WeLearn: 加载刷时长模式失败', error);
      return 'standard';
    }
  };

  /** 保存刷时长模式配置 */
  const saveDurationMode = (mode) => {
    try {
      if (DURATION_MODES[mode]) {
        localStorage.setItem(DURATION_MODE_KEY, mode);
      }
    } catch (error) {
      console.warn('WeLearn: 保存刷时长模式失败', error);
    }
  };

  /** 获取当前刷时长模式配置 */
  const getDurationConfig = () => {
    const mode = loadDurationMode();
    return DURATION_MODES[mode] || DURATION_MODES.standard;
  };

  /** 计算刷时长等待时间 */
  const calculateDurationTime = (questionCount) => {
    const config = getDurationConfig();
    const calculatedTime = Math.min(
      Math.max(questionCount * config.perQuestionTime, config.baseTime),
      config.maxTime
    );
    return calculatedTime;
  };

  // ==================== 版本检查功能 ====================

  /** 比较版本号,返回 1(a>b), -1(a<b), 0(a=b) */
  const compareVersions = (a, b) => {
    const partsA = a.replace(/^v/, '').split('.').map(Number);
    const partsB = b.replace(/^v/, '').split('.').map(Number);
    const len = Math.max(partsA.length, partsB.length);
    
    for (let i = 0; i < len; i++) {
      const numA = partsA[i] || 0;
      const numB = partsB[i] || 0;
      if (numA > numB) return 1;
      if (numA < numB) return -1;
    }
    return 0;
  };

  /** 从脚本内容提取版本号 */
  const extractVersionFromScript = (content) => {
    const match = content.match(/@version\s+(\d+\.\d+\.\d+)/);
    return match ? match[1] : null;
  };

  /** 检查是否有新版本 */
  const checkForUpdates = async () => {
    try {
      const handleUpdateFound = (ver) => {
        latestVersion = ver;
        showUpdateHint(ver);
      };

      // 检查缓存,避免频繁请求
      const cached = localStorage.getItem(UPDATE_CHECK_CACHE_KEY);
      if (cached) {
        const { version, timestamp } = JSON.parse(cached);
        if (Date.now() - timestamp < UPDATE_CHECK_INTERVAL) {
          // 使用缓存的版本信息
          if (version && compareVersions(version, VERSION) > 0) {
            handleUpdateFound(version);
          }
          return;
        }
      }

      // 请求最新脚本获取版本号
      const response = await fetch(UPDATE_CHECK_URL, {
        cache: 'no-cache',
        headers: { 'Accept': 'text/plain' }
      });
      
      if (!response.ok) {
        console.warn('[WeLearn-Go] 版本检查请求失败:', response.status);
        return;
      }

      const content = await response.text();
      const remoteVersion = extractVersionFromScript(content);
      
      if (!remoteVersion) {
        console.warn('[WeLearn-Go] 无法解析远程版本号');
        return;
      }

      // 缓存检查结果
      localStorage.setItem(UPDATE_CHECK_CACHE_KEY, JSON.stringify({
        version: remoteVersion,
        timestamp: Date.now()
      }));

      console.log('[WeLearn-Go] 版本检查:', { current: VERSION, remote: remoteVersion });

      // 如果有新版本,显示提示
      if (compareVersions(remoteVersion, VERSION) > 0) {
        handleUpdateFound(remoteVersion);
      }
    } catch (error) {
      console.warn('[WeLearn-Go] 版本检查失败:', error);
    }
  };

  /** 显示更新提示 */
  const showUpdateHint = (newVersion) => {
    const hint = document.querySelector('.welearn-update-hint');
    if (hint) {
      hint.textContent = `🆕 v${newVersion}`;
      hint.title = `发现新版本 v${newVersion},点击更新`;
      hint.style.display = 'inline';
    }
  };

  /**
   * 高亮显示两个字符串的差异
   * 返回带 HTML 标记的字符串,红色表示修改的部分
   */
  const highlightDiff = (original, modified) => {
    let result = '';
    const maxLen = Math.max(original.length, modified.length);
    
    for (let i = 0; i < maxLen; i++) {
      const origChar = original[i] || '';
      const modChar = modified[i] || '';
      
      if (origChar !== modChar) {
        result += `<em>${modChar}</em>`;
      } else {
        result += modChar;
      }
    }
    
    return result;
  };

  // ==================== 小错误生成策略 ====================

  /**
   * 键盘相邻字母映射表(基于 QWERTY 键盘布局)
   * 每个字母映射到其键盘上相邻的、容易误触的字母
   */
  const ADJACENT_KEYS = {
    a: ['s', 'q', 'z'],
    b: ['v', 'n', 'g', 'h'],
    c: ['x', 'v', 'd', 'f'],
    d: ['s', 'f', 'e', 'r', 'c', 'x'],
    e: ['w', 'r', 'd', 's'],
    f: ['d', 'g', 'r', 't', 'v', 'c'],
    g: ['f', 'h', 't', 'y', 'b', 'v'],
    h: ['g', 'j', 'y', 'u', 'n', 'b'],
    i: ['u', 'o', 'k', 'j'],
    j: ['h', 'k', 'u', 'i', 'm', 'n'],
    k: ['j', 'l', 'i', 'o', 'm'],
    l: ['k', 'o', 'p'],
    m: ['n', 'j', 'k'],
    n: ['b', 'm', 'h', 'j'],
    o: ['i', 'p', 'k', 'l'],
    p: ['o', 'l'],
    q: ['w', 'a'],
    r: ['e', 't', 'd', 'f'],
    s: ['a', 'd', 'w', 'e', 'x', 'z'],
    t: ['r', 'y', 'f', 'g'],
    u: ['y', 'i', 'h', 'j'],
    v: ['c', 'b', 'f', 'g'],
    w: ['q', 'e', 'a', 's'],
    x: ['z', 'c', 's', 'd'],
    y: ['t', 'u', 'g', 'h'],
    z: ['a', 's', 'x'],
  };

  /**
   * 常见的可交换字母对(非首字母位置)
   * 这些是打字时容易顺序颠倒的字母组合
   */
  const SWAPPABLE_PAIRS = ['ea', 'ae', 'ei', 'ie', 'ou', 'uo', 'er', 're', 'ru', 'ur', 'ti', 'it', 'th', 'ht', 'io', 'oi', 'an', 'na', 'en', 'ne', 'al', 'la'];

  /**
   * 错误类型1:键盘相邻字母拼写错误
   * 在单词中间(非首尾)将一个字母替换为键盘上相邻的字母
   */
  const makeAdjacentKeyMistake = (text) => {
    const words = text.split(/\s+/);
    // 筛选长度大于3的英文单词(确保有中间字母可替换)
    const candidates = words
      .map((word, index) => ({ word, index }))
      .filter(({ word }) => /^[a-z]+$/i.test(word) && word.length > 3);

    if (!candidates.length) return '';

    const { word, index: wordIndex } = candidates[randomInt(0, candidates.length - 1)];
    // 只在中间位置(非首尾)进行替换
    const charIndex = randomInt(1, word.length - 2);
    const originalChar = word[charIndex].toLowerCase();
    const adjacentChars = ADJACENT_KEYS[originalChar];

    if (!adjacentChars || !adjacentChars.length) return '';

    const replacement = adjacentChars[randomInt(0, adjacentChars.length - 1)];
    // 保持原始大小写
    const finalReplacement = word[charIndex] === word[charIndex].toUpperCase()
      ? replacement.toUpperCase()
      : replacement;

    const newWord = word.slice(0, charIndex) + finalReplacement + word.slice(charIndex + 1);
    words[wordIndex] = newWord;
    return words.join(' ');
  };

  /**
   * 错误类型2:字母顺序颠倒
   * 将单词中常见的字母对顺序颠倒(如 ea -> ae, ru -> ur)
   * 注意:不在首字母位置进行交换,且只处理纯字母单词(排除括号、斜杠等特殊字符)
   */
  const makeLetterSwapMistake = (text) => {
    const words = text.split(/\s+/);
    const candidates = [];

    // 查找包含可交换字母对的单词
    words.forEach((word, wordIndex) => {
      // 跳过长度不足的单词
      if (word.length < 3) return;
      // 只处理纯字母单词,排除包含 ()、/、数字等特殊字符的单词
      if (!/^[a-z]+$/i.test(word)) return;
      
      const lowerWord = word.toLowerCase();

      SWAPPABLE_PAIRS.forEach((pair) => {
        // 从位置1开始搜索,确保字母对不在首字母位置
        const pairIndex = lowerWord.indexOf(pair, 1);
        if (pairIndex > 0) { // 确保不在首字母位置(交换后首字母不会变)
          candidates.push({ word, wordIndex, pairIndex, pair });
        }
      });
    });

    if (!candidates.length) return '';

    const { word, wordIndex, pairIndex, pair } = candidates[randomInt(0, candidates.length - 1)];
    // 交换字母对
    const swapped = pair[1] + pair[0];
    // 保持原始大小写
    let finalSwapped = '';
    for (let i = 0; i < 2; i++) {
      const origChar = word[pairIndex + i];
      const newChar = swapped[i];
      finalSwapped += origChar === origChar.toUpperCase() ? newChar.toUpperCase() : newChar;
    }

    const newWord = word.slice(0, pairIndex) + finalSwapped + word.slice(pairIndex + 2);
    words[wordIndex] = newWord;
    return words.join(' ');
  };

  /**
   * 错误类型3:句子首字母大小写错误
   * 将句子首字母的大小写切换
   */
  const makeCapitalizationMistake = (text) => {
    const trimmed = text.trim();
    if (!trimmed.length) return '';

    // 检查是否像句子(以字母开头)
    const firstChar = trimmed[0];
    if (!/[a-z]/i.test(firstChar)) return '';

    // 切换首字母大小写
    const toggledFirst = firstChar === firstChar.toUpperCase()
      ? firstChar.toLowerCase()
      : firstChar.toUpperCase();

    return toggledFirst + trimmed.slice(1);
  };

  /**
   * 错误类型4:句子末尾标点符号错误
   * 删除或添加句子末尾的标点符号
   */
  const makePunctuationMistake = (text) => {
    const trimmed = text.trimEnd();
    if (!trimmed.length) return '';

    const trailingSpaces = text.slice(trimmed.length);
    const endsWithPunctuation = /[.!?]$/.test(trimmed);

    if (endsWithPunctuation) {
      // 删除末尾标点
      return trimmed.slice(0, -1) + trailingSpaces;
    } else {
      // 检查是否像句子(以大写字母开头,且有一定长度)
      if (trimmed.length > 10 && /^[A-Z]/.test(trimmed)) {
        // 添加句号
        return trimmed + '.' + trailingSpaces;
      }
    }

    return '';
  };

  /**
   * 错误类型名称映射
   */
  const MISTAKE_TYPE_NAMES = {
    adjacentKey: '键盘误触',
    letterSwap: '字母顺序',
    capitalization: '大小写',
    punctuation: '标点',
  };

  /**
   * 提取变化的单词(用于错误显示)
   */
  const findChangedWord = (original, modified) => {
    const origWords = original.split(/\s+/);
    const modWords = modified.split(/\s+/);
    
    // 找到变化的单词
    for (let i = 0; i < origWords.length; i++) {
      if (origWords[i] !== modWords[i]) {
        return { original: origWords[i], modified: modWords[i] };
      }
    }
    
    // 如果是整体变化(如首字母大小写、标点),截取前15个字符
    const len = Math.min(15, original.length);
    return {
      original: original.slice(0, len) + (original.length > len ? '...' : ''),
      modified: modified.slice(0, len) + (modified.length > len ? '...' : ''),
    };
  };

  /**
   * 创建错误生成器
   * @param {boolean} enabled - 是否启用错误生成
   * @returns {Object} 包含 mutate 函数和 getErrors 方法的对象
   */
  const createMistakeMutator = (enabled) => {
    if (!enabled) {
      return {
        mutate: (value) => value,
        getErrors: () => [],
        getTargetCount: () => 0,
      };
    }

    const errors = [];
    // 按用户配置的权重随机选择错误数量
    const targetCount = weightedRandom(getErrorCountWeights());
    let remaining = targetCount;

    // 策略列表
    const strategies = [
      { fn: makeAdjacentKeyMistake, type: 'adjacentKey' },
      { fn: makeLetterSwapMistake, type: 'letterSwap' },
      { fn: makeCapitalizationMistake, type: 'capitalization' },
      { fn: makePunctuationMistake, type: 'punctuation' },
    ];

    const mutate = (value) => {
      if (remaining <= 0) return value;

      // Fisher-Yates 洗牌
      for (let i = strategies.length - 1; i > 0; i--) {
        const j = randomInt(0, i);
        [strategies[i], strategies[j]] = [strategies[j], strategies[i]];
      }

      for (const { fn, type } of strategies) {
        const next = fn(value);
        if (next && next !== value) {
          remaining--;
          const changed = findChangedWord(value, next);
          errors.push({
            type: MISTAKE_TYPE_NAMES[type],
            ...changed,
          });
          return next;
        }
      }

      return value;
    };

    return { mutate, getErrors: () => errors, getTargetCount: () => targetCount };
  };

  // ==================== 答案填充逻辑 ====================

  /**
   * 规范化答案文本,清理多余的换行和空格
   * 将多个连续空白字符(包括换行)合并为单个空格
   */
  const normalizeAnswer = (text) => {
    if (!text) return '';
    return text
      .replace(/\s+/g, ' ')  // 将所有连续空白字符(包括换行、制表符)替换为单个空格
      .trim();
  };

  /**
   * 清理 Group Work 类型答案的前缀
   * 移除 "(Answers may vary.)" 等提示语
   */
  const cleanGroupWorkAnswer = (text) => {
    if (!text) return '';
    return text
      // 移除 "(Answers may vary.)" 及其变体
      .replace(/\(?\s*Answers?\s+may\s+vary\.?\s*\)?/gi, '')
      // 移除 "(Sample answer)" 等
      .replace(/\(?\s*Sample\s+answers?\.?\s*\)?/gi, '')
      // 移除 "(Reference answer)" 等
      .replace(/\(?\s*Reference\s+answers?\.?\s*\)?/gi, '')
      // 移除 "(Suggested answer)" 等
      .replace(/\(?\s*Suggested\s+answers?\.?\s*\)?/gi, '')
      // 移除开头的空白
      .trim();
  };

  /** 从容器中读取正确答案 */
  const readSolution = (input, container) => {
    const resultNode = container.querySelector('[data-itemtype="result"]');
    let resultText = resultNode?.textContent;
    
    if (resultText) {
      // 对于 fillinglong(主观题),清理前缀
      const isLongFilling = container.getAttribute('data-controltype') === 'fillinglong';
      if (isLongFilling) {
        resultText = cleanGroupWorkAnswer(resultText);
      }
      return normalizeAnswer(resultText);
    }

    const solutionFromInput = input?.dataset?.solution;
    if (!solutionFromInput) return '';

    const normalized = normalizeAnswer(solutionFromInput);
    const candidates = splitSolutions(normalized);
    return candidates[0] ?? '';
  };

  /** 填充填空题 */
  const fillFillingItem = (container, mutateAnswer) => {
    // 支持多种输入元素格式:data-itemtype 属性或直接使用 textarea 标签
    const input = container.querySelector('[data-itemtype="input"], [data-itemtype="textarea"], textarea');
    if (!input) {
      console.debug('[WeLearn-Go] fillFillingItem: 找不到 input 元素', container.outerHTML?.slice(0, 100));
      return false;
    }
    
    // 获取控件类型
    const controlType = container.getAttribute('data-controltype');
    console.debug('[WeLearn-Go] fillFillingItem:', { controlType, tagName: input.tagName, id: container.getAttribute('data-id') });
    
    // 对于主观题(fillinglong),检查是否有实质性答案
    if (controlType === 'fillinglong') {
      // 获取原始答案文本
      const resultEl = container.querySelector('[data-itemtype="result"]');
      const rawAnswer = resultEl?.textContent?.trim() || '';
      
      // 检查是否只有 "Answers may vary" 类的占位文本
      const cleanedAnswer = cleanGroupWorkAnswer(rawAnswer);
      if (!cleanedAnswer) {
        // 没有实质性答案,跳过填充(留空)
        console.info('[WeLearn-Go] fillinglong 无实质答案,跳过:', rawAnswer.slice(0, 50));
        return false;
      }
      console.debug('[WeLearn-Go] fillinglong 有实质答案,继续填充');
    }
    
    const solution = readSolution(input, container);
    if (!solution) {
      console.debug('[WeLearn-Go] fillFillingItem: 无法读取答案');
      return false;
    }
    console.debug('[WeLearn-Go] fillFillingItem: 读取到答案:', solution.slice(0, 50));
    
    const finalValue = mutateAnswer(solution);
    const formattedValue =
      input.tagName === 'TEXTAREA'
        ? formatSolutionText(finalValue, { collapseLines: groupWorkDetected })
        : finalValue.trim();
    if (input.value.trim() === formattedValue) {
      console.debug('[WeLearn-Go] fillFillingItem: 值已相同,跳过');
      return false;
    }
    input.value = formattedValue;
    input.dispatchEvent(new Event('input', { bubbles: true }));
    input.dispatchEvent(new Event('change', { bubbles: true }));
    console.debug('[WeLearn-Go] fillFillingItem: 填充成功');
    return true;
  };

  /** 选择选项(单选/多选) */
  const selectChoiceOption = (option) => {
    const input = option.querySelector('input[type="radio"], input[type="checkbox"]');
    if (input) {
      if (input.checked) return false;
      input.click();
      return true;
    }

    // 检测多种已选状态:CSS 类、aria-checked 属性、data-choiced 属性(T/F/N 判断题使用)
    const wasSelected = option.classList.contains('selected') || 
                        option.getAttribute('aria-checked') === 'true' ||
                        option.hasAttribute('data-choiced');
    option.click();
    return !wasSelected;
  };

  /** 查找正确答案选项 */
  const findChoiceSolutions = (options, container) => {
    const optionsWithSolution = options.filter((item) => item.hasAttribute('data-solution'));
    if (optionsWithSolution.length) return optionsWithSolution;

    const extractCandidates = (raw) => splitSolutions(raw || '').map(normalizeText);

    const candidates = [
      ...extractCandidates(container.querySelector('[data-itemtype="result"]')?.textContent),
      ...extractCandidates(container.dataset?.solution),
    ];

    if (!candidates.length) return [];

    return options.filter((item) => {
      const optionText = normalizeText(item.textContent);
      const optionSolution = normalizeText(item.dataset?.solution);
      return candidates.includes(optionText) || candidates.includes(optionSolution);
    });
  };

  /** 填充选择题(单选/多选/T-F-N 判断题) */
  const fillChoiceItem = (container) => {
    const containerId = container.getAttribute('data-id') || container.id || 'unknown';
    const options = Array.from(container.querySelectorAll('ul[data-itemtype="options"] > li'));
    
    console.debug('[WeLearn-Go] fillChoiceItem:', {
      containerId,
      optionsCount: options.length,
      optionTexts: options.map(o => o.textContent?.trim())
    });
    
    if (!options.length) {
      console.debug('[WeLearn-Go] fillChoiceItem: 未找到选项, 容器:', containerId);
      return false;
    }

    const matchedOptions = findChoiceSolutions(options, container);
    console.debug('[WeLearn-Go] fillChoiceItem: 匹配到的正确答案:', {
      containerId,
      matchedCount: matchedOptions.length,
      matchedTexts: matchedOptions.map(o => o.textContent?.trim()),
      matchedHasSolution: matchedOptions.map(o => o.hasAttribute('data-solution'))
    });
    
    if (!matchedOptions.length) {
      console.debug('[WeLearn-Go] fillChoiceItem: 未找到正确答案, 容器:', containerId);
      return false;
    }

    const isCheckboxGroup = options.some((item) => item.querySelector('input[type="checkbox"]'));
    if (isCheckboxGroup) {
      return matchedOptions.reduce((changed, option) => selectChoiceOption(option) || changed, false);
    }

    return selectChoiceOption(matchedOptions[0]);
  };

  // ==================== AngularJS 组件适配(et-* 系列) ====================

  // 点击选择类型的填充队列(串行执行避免选项面板冲突)
  const clickFillQueue = [];
  let isProcessingClickQueue = false;
  let clickQueueSchedulerId = null;

  const scheduleClickQueueProcessing = () => {
    if (clickQueueSchedulerId !== null) return;

    const run = () => {
      clickQueueSchedulerId = null;
      processClickFillQueue();
    };

    if (typeof requestAnimationFrame === 'function') {
      clickQueueSchedulerId = requestAnimationFrame(run);
    } else {
      clickQueueSchedulerId = setTimeout(run, 0);
    }
  };

  /**
   * 处理点击填充队列
   */
  const processClickFillQueue = async () => {
    console.info('[WeLearn-Go] processClickFillQueue: 被调用', { 
      isProcessingClickQueue, 
      queueLength: clickFillQueue.length 
    });
    
    if (isProcessingClickQueue || clickFillQueue.length === 0) {
      return;
    }
    
    console.info('[WeLearn-Go] processClickFillQueue: 开始处理队列');
    isProcessingClickQueue = true;
    
    while (clickFillQueue.length > 0) {
      const { container, solution } = clickFillQueue.shift();
      console.info('[WeLearn-Go] processClickFillQueue: 处理队列项', { 
        solution, 
        id: container.id,
        remaining: clickFillQueue.length
      });
      await doFillEtBlankByClick(container, solution);
      // 给 AngularJS 一点时间完成 digest
      await new Promise(resolve => setTimeout(resolve, 50));
    }
    
    isProcessingClickQueue = false;
    console.info('[WeLearn-Go] processClickFillQueue: 队列处理完成');
  };

  /**
   * 从答案中提取纯文本(去除选项字母前缀如 "A. "、"B. " 等)
   * @param {string} solution - 完整答案(如 "D. open")
   * @returns {string} 纯文本答案(如 "open")
   */
  const extractPureAnswer = (solution) => {
    // 匹配格式:字母 + 点/括号 + 可选空格 + 答案内容
    // 如 "A. open", "B) answer", "C answer" 等
    const match = solution.match(/^[A-Za-z][.\)]\s*(.+)$/);
    return match ? match[1].trim() : solution;
  };

  /**
   * 检查选项文本是否与答案匹配
   * 支持完整匹配(如 "D. open" === "D. open")
   * 以及去除前缀后的匹配(如 "open" 匹配 "D. open")
   * @param {string} optionText - 选项文本
   * @param {string} solution - 答案
   * @returns {boolean} 是否匹配
   */
  const isOptionMatch = (optionText, solution) => {
    const normalizedOpt = normalizeAnswer(optionText);
    const normalizedSol = normalizeAnswer(solution);
    
    // 完全匹配
    if (normalizedOpt === normalizedSol) return true;
    
    // 去除前缀后匹配
    const pureAnswer = extractPureAnswer(normalizedSol);
    if (normalizedOpt === normalizeAnswer(pureAnswer)) return true;
    
    // 选项可能也带前缀,去除后比较
    const pureOption = extractPureAnswer(normalizedOpt);
    if (pureOption === normalizeAnswer(pureAnswer)) return true;
    
    return false;
  };

  /**
   * 实际执行点击选项填充 et-blank
   * 直接修改 DOM 内容,不依赖 AngularJS
   * @param {Element} container - et-blank 容器元素
   * @param {string} solution - 答案
   * @returns {Promise<boolean>} 是否成功填充
   */
  const doFillEtBlankByClick = (container, solution) => {
    console.info('[WeLearn-Go] doFillEtBlankByClick: 开始处理', { solution, id: container.id });
    
    return new Promise((resolve) => {
      const blankEl = container.querySelector('span.blank');
      
      if (!blankEl) {
        console.warn('[WeLearn-Go] doFillEtBlankByClick: 未找到 blank 元素');
        resolve(false);
        return;
      }
      
      const doc = container.ownerDocument || document;
      
      // 步骤1: 点击 blank 元素激活 optionsPicker
      console.info('[WeLearn-Go] doFillEtBlankByClick: 点击 blank 激活选项', { id: container.id });
      blankEl.click();
      
      // 步骤2: 等待 optionsPicker 出现,然后点击对应选项
      setTimeout(() => {
        // 查找可见的 optionsPicker
        const picker = doc.querySelector('.optionsPicker.visible') || doc.querySelector('.optionsPicker');
        
        if (!picker) {
          console.warn('[WeLearn-Go] doFillEtBlankByClick: 未找到 optionsPicker');
          // 回退方案:直接设置文本
          blankEl.textContent = solution;
          resolve(true);
          return;
        }
        
        // 查找匹配的选项
        const pickerItems = picker.querySelectorAll('li[option]');
        let targetOption = null;
        
        for (const li of pickerItems) {
          const optionText = li.textContent?.trim();
          // 精确匹配或者去掉字母前缀后匹配
          if (optionText === solution || isOptionMatch(optionText, solution)) {
            // 跳过已使用的选项
            if (!li.classList.contains('used')) {
              targetOption = li;
              break;
            }
          }
        }
        
        if (targetOption) {
          console.info('[WeLearn-Go] doFillEtBlankByClick: 点击选项', { 
            option: targetOption.textContent?.trim(),
            solution
          });
          targetOption.click();
          resolve(true);
        } else {
          console.warn('[WeLearn-Go] doFillEtBlankByClick: 未找到匹配的选项', { 
            solution, 
            available: Array.from(pickerItems).map(li => li.textContent?.trim())
          });
          // 回退方案:直接设置文本
          blankEl.textContent = solution;
          resolve(true);
        }
      }, 100); // 等待 optionsPicker 出现
    });
  };

  /**
   * 通过点击选项填充 et-blank(用于带有 noinput 属性的选择题)
   * @param {Element} container - et-blank 容器元素
   * @param {string} solution - 答案
   * @returns {boolean} 是否成功填充(加入队列)
   */
  const fillEtBlankByClick = (container, solution) => {
    // 获取当前值
    const blankEl = container.querySelector('span.blank');
    if (blankEl) {
      const currentValue = blankEl.textContent?.trim() || '';
      const isAlreadyFilled = isOptionMatch(currentValue, solution);
      console.info('[WeLearn-Go] fillEtBlankByClick: 检查', { 
        currentValue, 
        solution, 
        match: isAlreadyFilled,
        id: container.id
      });
      if (isAlreadyFilled) {
        return false; // 已填充
      }
    }
    
    console.info('[WeLearn-Go] fillEtBlankByClick: 加入队列', { solution, id: container.id });
    
    // 加入队列
    clickFillQueue.push({ container, solution });
    console.info('[WeLearn-Go] fillEtBlankByClick: 队列长度', clickFillQueue.length);
    
    // 调度处理队列
    scheduleClickQueueProcessing();
    
    return true;
  };

  /**
   * 填充 et-blank 填空题
   * 答案可能在以下位置:
   * 1. et-blank 内部的 span.key 元素
   * 2. et-blank 父级容器的兄弟元素 .visible-box 中(句型练习题)
   * 支持两种输入方式:
   * - 普通输入:textarea, input, contenteditable
   * - 点击选择:带有 noinput 属性,需要点击 et-options 中的选项
   * 
   * 答案来源(按优先级):
   * 1. et-blank 内部的 span.key 元素(WELearnHelper 方式,用 | 分隔多选项)
   * 2. 父级的 .visible-box 元素
   * 3. g 属性
   * 4. 全局上下文
   * 
   * @param {Element} container - et-blank 容器元素
   * @param {Function} mutateAnswer - 答案变异函数(用于生成小错误)
   * @returns {boolean} 是否成功填充
   */
  const fillEtBlank = (container, mutateAnswer) => {
    let solution = '';
    
    // 方法1: 查找 et-blank 内部的 span.key 或 .key 元素(WELearnHelper 的核心方式)
    const keyEl = container.querySelector('span.key, .key');
    if (keyEl) {
      // WELearnHelper: 答案可能用 | 分隔多个选项,取第一个
      const rawText = keyEl.textContent || '';
      solution = normalizeAnswer(rawText.split('|')[0]);
    }
    
    // 方法2: 查找父级容器的兄弟元素 .visible-box(句型练习题)
    if (!solution) {
      // 向上查找包含 et-blank 的容器(通常是 div[et-stem-index] 或直接父级)
      const stemContainer = container.closest('[et-stem-index]') || container.parentElement?.parentElement;
      if (stemContainer) {
        const visibleBox = stemContainer.querySelector('.visible-box');
        if (visibleBox) {
          solution = normalizeAnswer(visibleBox.textContent);
          console.debug('[WeLearn-Go] fillEtBlank: 从 .visible-box 获取答案');
        }
      }
    }
    
    // 方法3: 查找同级的 .visible-box
    if (!solution && container.parentElement) {
      const sibling = container.parentElement.querySelector('.visible-box');
      if (sibling) {
        solution = normalizeAnswer(sibling.textContent);
        console.debug('[WeLearn-Go] fillEtBlank: 从同级 .visible-box 获取答案');
      }
    }
    
    // 方法4: 从 g 属性获取答案(某些题型的答案存储在此)
    if (!solution) {
      const gAttr = container.getAttribute('g');
      if (gAttr && gAttr.trim()) {
        try {
          // g 属性可能是 JSON 或纯文本
          const parsed = JSON.parse(gAttr);
          if (typeof parsed === 'string') {
            solution = normalizeAnswer(parsed);
          } else if (parsed.answer || parsed.key) {
            solution = normalizeAnswer(parsed.answer || parsed.key);
          }
        } catch {
          // 不是 JSON,直接使用
          solution = normalizeAnswer(gAttr);
        }
        if (solution) {
          console.debug('[WeLearn-Go] fillEtBlank: 从 g 属性获取答案');
        }
      }
    }
    
    // 方法5: 从全局上下文获取答案
    if (!solution) {
      const globalAnswer = findAnswerFromGlobalContext(container);
      if (globalAnswer) {
        solution = normalizeAnswer(globalAnswer);
        console.debug('[WeLearn-Go] fillEtBlank: 从全局上下文获取答案');
      }
    }
    
    if (!solution) {
      // 检测是否为开放式无答案练习(g="" 且 noprogress)
      const gAttr = container.getAttribute('g');
      const isOpenEnded = gAttr === '' || gAttr === null;
      const hasNoprogress = container.hasAttribute('noprogress');
      
      if (isOpenEnded && hasNoprogress) {
        console.info('[WeLearn-Go] fillEtBlank: 跳过开放式练习(无标准答案)', container.id);
      } else {
        console.debug('[WeLearn-Go] fillEtBlank: 未找到答案', container.outerHTML?.substring(0, 200));
      }
      return false;
    }

    // 检查是否为点击选择类型(带有 noinput 属性)
    const isNoInput = container.hasAttribute('noinput');
    
    console.info('[WeLearn-Go] fillEtBlank: 处理', { 
      isNoInput, 
      solution: solution.substring(0, 30),
      id: container.id
    });
    
    if (isNoInput) {
      // 点击选择类型:需要先点击 blank 激活,然后点击对应的选项
      return fillEtBlankByClick(container, solution);
    }

    // 普通输入类型:查找输入区域(优先真实输入元素)
    const textInputSelector = 'textarea, [contenteditable], input.blank, input[type="text"]';
    let inputEl = container.querySelector(textInputSelector);

    if (!inputEl) {
      const etItem = container.closest('et-item');
      if (etItem) {
        const candidateInputs = Array.from(etItem.querySelectorAll(textInputSelector))
          .filter((el) => !el.closest('et-blank'));
        if (candidateInputs.length) {
          const blanksNeedingExternal = Array.from(etItem.querySelectorAll('et-blank'))
            .filter((blank) => !blank.querySelector(textInputSelector));
          const externalIndex = blanksNeedingExternal.indexOf(container);
          if (externalIndex > -1) {
            inputEl = candidateInputs[externalIndex] || null;
          }
        }
      }
    }

    if (!inputEl) {
      const scopeDoc = container.ownerDocument || document;
      inputEl = scopeDoc.querySelector(`[data-blank-id="${container.id}"]`) ||
                scopeDoc.querySelector(`[blank-id="${container.id}"]`) ||
                scopeDoc.querySelector(`[data-target="${container.id}"]`);
    }

    console.info('[WeLearn-Go] fillEtBlank: 查找输入元素', { 
      found: !!inputEl, 
      tagName: inputEl?.tagName,
      hasContentEditable: inputEl ? inputEl.hasAttribute?.('contenteditable') : false,
      containerHTML: container.innerHTML?.substring(0, 300)
    });
    if (!inputEl) {
      console.info('[WeLearn-Go] fillEtBlank: 未找到输入元素');
      return false;
    }

    const finalValue = mutateAnswer(solution);
    
    // 获取当前值(根据元素类型)
    const isContentEditable = inputEl.hasAttribute('contenteditable');
    const currentValue = (inputEl.tagName === 'TEXTAREA' || inputEl.tagName === 'INPUT') && !isContentEditable
      ? normalizeAnswer(inputEl.value)
      : normalizeAnswer(inputEl.textContent);
    
    // 如果已填充相同答案,跳过
    if (currentValue === finalValue) {
      console.info('[WeLearn-Go] fillEtBlank: 已填充相同答案,跳过', { currentValue, finalValue });
      return false;
    }

    // WELearnHelper 的事件触发策略:
    // 输入前事件序列
    const triggerReadyEvents = (el) => {
      try {
        el.click?.();
        el.focus?.();
        el.dispatchEvent(new Event('click', { bubbles: true }));
        el.dispatchEvent(new Event('focus', { bubbles: true }));
        el.dispatchEvent(new KeyboardEvent('keydown', { bubbles: true }));
        el.dispatchEvent(new Event('input', { bubbles: true }));
      } catch (e) { /* 忽略 */ }
    };
    
    // 输入后事件序列
    const triggerCompleteEvents = (el) => {
      try {
        el.dispatchEvent(new KeyboardEvent('keyup', { bubbles: true }));
        el.dispatchEvent(new Event('change', { bubbles: true }));
        el.dispatchEvent(new Event('blur', { bubbles: true }));
        
        // AngularJS 事件触发
        const win = el.ownerDocument?.defaultView || window;
        const angular = win.angular;
        if (angular) {
          angular.element(el).triggerHandler?.('hover');
          angular.element(el).triggerHandler?.('keyup');
          angular.element(el).triggerHandler?.('blur');
        }
      } catch (e) { /* 忽略 */ }
    };

    // 填充答案 - 根据元素类型选择正确的方式
    console.debug('[WeLearn-Go] fillEtBlank: 填充', { solution: solution.substring(0, 50), inputEl: inputEl.tagName, isContentEditable });
    
    // 触发准备事件
    triggerReadyEvents(inputEl);
    
    if ((inputEl.tagName === 'INPUT' || inputEl.tagName === 'TEXTAREA') && !isContentEditable) {
      inputEl.value = finalValue;
    } else {
      // contenteditable 或 span 元素 (WELearnHelper 使用 span.blank)
      inputEl.textContent = finalValue;
    }
    
    // 触发完成事件
    triggerCompleteEvents(inputEl);
    
    // 尝试触发 AngularJS 的数据绑定更新
    try {
      const win = inputEl.ownerDocument?.defaultView || window;
      const ngModelController = win.angular?.element(inputEl)?.controller('ngModel');
      if (ngModelController) {
        ngModelController.$setViewValue(finalValue);
        ngModelController.$render();
      }
      // 触发 AngularJS 的 $apply
      const scope = win.angular?.element(inputEl)?.scope();
      if (scope && scope.$apply) {
        scope.$apply();
      }
    } catch (e) { /* 忽略 AngularJS 相关错误 */ }

    return true;
  };

  /**
   * 填充 et-multi-noinput 多选题
   * 有两种模式:
   * 1. 选择填空模式:点击 span.multi-noinput 激活 multiOptionsPicker 浮窗,然后选择选项
   * 2. 直接选择模式:直接点击 et-multi-options 中的选项
   * 答案存储在 span.key 中(格式如 "B,I,D,K,E")
   * @param {Element} container - et-multi-noinput 容器元素或其父容器
   * @returns {boolean} 是否成功填充
   */
  const fillEtMultiNoinput = (container) => {
    // 查找答案:在 span.key 元素中
    const keyEl = container.querySelector('span.key');
    if (!keyEl) return false;
    
    const solutionText = keyEl.textContent?.trim();
    if (!solutionText) return false;

    // 解析正确答案(格式如 "B,I,D,K,E")
    const correctOptions = solutionText.split(',').map(s => s.trim().toUpperCase()).filter(Boolean);
    if (!correctOptions.length) return false;

    // 检查是否为选择填空模式(有 span.multi-noinput)
    const multiNoinputSpan = container.querySelector('span.multi-noinput');
    if (multiNoinputSpan) {
      // 选择填空模式:需要点击激活浮窗,然后依次选择选项
      console.info('[WeLearn-Go] fillEtMultiNoinput: 选择填空模式', { 
        id: container.id, 
        correctOptions 
      });
      
      // 加入异步队列处理
      fillMultiNoinputByClick(container, correctOptions);
      return true;
    }

    // 直接选择模式:查找 et-multi-options 中的选项列表
    const optionsContainer = container.closest('et-item')?.querySelector('et-multi-options ul') ||
                             container.parentElement?.querySelector('et-multi-options ul');
    if (!optionsContainer) return false;

    const optionItems = Array.from(optionsContainer.querySelectorAll('li'));
    let changed = false;

    optionItems.forEach((li) => {
      // 提取选项字母(通常在 li 开头,如 "A. ...")
      const optionMatch = li.textContent?.trim().match(/^([A-Z])\./i);
      if (!optionMatch) return;
      
      const optionLetter = optionMatch[1].toUpperCase();
      const shouldBeSelected = correctOptions.includes(optionLetter);
      const isCurrentlySelected = li.classList.contains('selected') || 
                                  li.classList.contains('used') ||
                                  li.getAttribute('aria-checked') === 'true';

      // 如果选中状态需要改变
      if (shouldBeSelected !== isCurrentlySelected) {
        li.click();
        changed = true;
      }
    });

    return changed;
  };

  /**
   * 通过点击选项填充 et-multi-noinput(选择填空模式)
   * 需要先点击 span.multi-noinput 激活浮窗,然后依次点击所有正确选项
   * @param {Element} container - et-multi-noinput 容器元素
   * @param {string[]} correctOptions - 正确选项字母数组,如 ['B', 'I', 'D', 'K', 'E']
   */
  const fillMultiNoinputByClick = async (container, correctOptions) => {
    const multiNoinputSpan = container.querySelector('span.multi-noinput');
    if (!multiNoinputSpan) return;

    const doc = container.ownerDocument || document;
    
    console.info('[WeLearn-Go] fillMultiNoinputByClick: 开始处理', { 
      id: container.id, 
      correctOptions 
    });

    // 步骤1: 点击 multi-noinput 激活浮窗
    multiNoinputSpan.click();
    
    // 等待浮窗出现
    await new Promise(resolve => setTimeout(resolve, 200));

    // 步骤2: 查找浮窗 - 浮窗在 et-item 之后的同级位置
    // 先尝试查找可见的浮窗
    let picker = doc.querySelector('.multiOptionsPicker.visible');
    
    // 如果没找到可见的,尝试查找任意浮窗
    if (!picker) {
      picker = doc.querySelector('.multiOptionsPicker');
    }
    
    // 如果还是没找到,尝试在 body 级别查找(有时浮窗会被移到 body 下)
    if (!picker) {
      picker = doc.body?.querySelector('.multiOptionsPicker');
    }
    
    if (!picker) {
      console.warn('[WeLearn-Go] fillMultiNoinputByClick: 未找到 multiOptionsPicker');
      return;
    }

    console.info('[WeLearn-Go] fillMultiNoinputByClick: 找到浮窗', { 
      visible: picker.classList.contains('visible'),
      optionsCount: picker.querySelectorAll('li[preoption]').length
    });

    const pickerItems = picker.querySelectorAll('li[preoption]');
    
    // 依次点击每个正确选项
    for (const optionLetter of correctOptions) {
      // 每次点击前,重新点击 multi-noinput 确保浮窗激活
      multiNoinputSpan.click();
      await new Promise(resolve => setTimeout(resolve, 100));
      
      // 重新获取浮窗(因为可能会重新渲染)
      const currentPicker = doc.querySelector('.multiOptionsPicker.visible') || 
                            doc.querySelector('.multiOptionsPicker');
      if (!currentPicker) {
        console.warn('[WeLearn-Go] fillMultiNoinputByClick: 浮窗消失了');
        continue;
      }
      
      const currentItems = currentPicker.querySelectorAll('li[preoption]');
      
      for (const li of currentItems) {
        const optionMatch = li.textContent?.trim().match(/^([A-Z])\./i);
        if (optionMatch && optionMatch[1].toUpperCase() === optionLetter) {
          // 检查是否已被选中(有 used class)
          if (!li.classList.contains('used')) {
            console.info('[WeLearn-Go] fillMultiNoinputByClick: 点击选项', optionLetter);
            li.click();
            // 等待系统处理
            await new Promise(resolve => setTimeout(resolve, 100));
          } else {
            console.info('[WeLearn-Go] fillMultiNoinputByClick: 选项已使用,跳过', optionLetter);
          }
          break;
        }
      }
    }

    console.info('[WeLearn-Go] fillMultiNoinputByClick: 完成', { id: container.id });
  };

  /**
   * 检测并处理 et-song 类型(朗读/引用音频练习)
   * 这种类型通常是无需交互的阅读材料,标记为 notscored
   * @param {Element} container - et-item 容器元素
   * @returns {boolean} 是否为 et-song 类型
   */
  const isEtSongItem = (container) => {
    return container.querySelector('et-song') !== null;
  };

  /**
   * 检测是否为开放式练习(无标准答案,需要用户自行填写)
   * 特征:et-blank 的 g 属性为空,且没有任何答案来源(.key 元素或 .visible-box)
   * @param {Element} container - et-item 容器元素
   * @returns {boolean} 是否为开放式练习
   */
  const isOpenEndedItem = (container) => {
    const blanks = container.querySelectorAll('et-blank');
    if (blanks.length === 0) return false;
    
    // 检查是否所有 et-blank 都没有答案来源
    const allBlanksEmpty = Array.from(blanks).every(blank => {
      // 检查 g 属性
      const gAttr = blank.getAttribute('g');
      if (gAttr && gAttr.trim()) return false;
      
      // 检查内部 .key 元素
      const keyEl = blank.querySelector('.key, span.key');
      if (keyEl?.textContent?.trim()) return false;
      
      // 检查同级或父级的 .visible-box
      const stemContainer = blank.closest('[et-stem-index]') || blank.parentElement?.parentElement;
      if (stemContainer) {
        const visibleBox = stemContainer.querySelector('.visible-box');
        if (visibleBox?.textContent?.trim()) return false;
      }
      
      // 检查直接父级的 .visible-box
      if (blank.parentElement) {
        const sibling = blank.parentElement.querySelector('.visible-box');
        if (sibling?.textContent?.trim()) return false;
      }
      
      return true;
    });
    
    if (!allBlanksEmpty) return false;
    
    // 如果所有空格都没有答案,且包含 et-recorder(录音)或 notscored,则认为是开放式练习
    const hasRecorder = container.querySelector('et-recorder') !== null;
    
    return hasRecorder || container.hasAttribute('notscored');
  };

  /**
   * 检测是否为无交互类型的 et-item
   * 注意:notscored 属性只表示不计分,不意味着不需要填写
   * @param {Element} container - et-item 容器元素
   * @returns {boolean} 是否为无交互类型
   */
  const isNoInteractionItem = (container) => {
    // 检查是否包含 et-song(朗读/引用类型)- 这种确实不需要交互
    if (isEtSongItem(container)) return true;
    
    // 检查是否有可填写的元素(包括 textarea)
    const hasInputElements = container.querySelector('et-blank, et-multi-noinput, et-multi-options, et-recorder, et-choice, et-tof, et-matching, [contenteditable="true"], textarea, input[type="text"]');

    // 如果没有任何可填写的元素,才认为是无交互类型
    if (!hasInputElements) return true;    return false;
  };

  /**
   * 填充 et-item 容器中的所有题目
   * @param {Element} container - et-item 容器元素
   * @param {Function} mutateAnswer - 答案变异函数
   * @returns {boolean} 是否有任何填充操作
   */
  const fillEtItem = (container, mutateAnswer) => {
    // 跳过无交互类型
    if (isNoInteractionItem(container)) {
      return false;
    }

    // 检测开放式练习(无标准答案)
    if (isOpenEndedItem(container)) {
      console.info('[WeLearn-Go] fillEtItem: 检测到开放式练习(无标准答案)', container.id || container.getAttribute('uuid'));
      handleOpenEndedExercise(container);
      return false;
    }

    let filled = false;

    // 填充 et-blank 填空题
    const blanks = Array.from(container.querySelectorAll('et-blank'));
    console.info('[WeLearn-Go] fillEtItem: 找到 et-blank 数量:', blanks.length);
    blanks.forEach((blank) => {
      const changed = fillEtBlank(blank, mutateAnswer);
      console.info('[WeLearn-Go] fillEtBlank 返回:', changed, blank.id);
      filled = filled || changed;
    });

    // 填充 et-multi-noinput 多选题
    const multiNoinputs = Array.from(container.querySelectorAll('et-multi-noinput'));
    multiNoinputs.forEach((multi) => {
      const changed = fillEtMultiNoinput(multi);
      filled = filled || changed;
    });

    // 填充 et-toggle 对话填空题
    const toggles = Array.from(container.querySelectorAll('et-toggle'));
    toggles.forEach((toggle) => {
      const changed = fillEtToggle(toggle, mutateAnswer);
      filled = filled || changed;
    });

    // 填充 et-choice 二选一选择题
    const etChoices = Array.from(container.querySelectorAll('et-choice'));
    etChoices.forEach((choice) => {
      const changed = fillEtChoice(choice);
      filled = filled || changed;
    });

    // 填充 et-tof 判断题(True/False 或自定义标签如 B/S)
    const etTofs = Array.from(container.querySelectorAll('et-tof'));
    etTofs.forEach((tof) => {
      const changed = fillEtTof(tof);
      filled = filled || changed;
    });

    // 填充 et-matching 连线题
    const etMatchings = Array.from(container.querySelectorAll('et-matching'));
    etMatchings.forEach((matching) => {
      const changed = fillEtMatching(matching);
      filled = filled || changed;
    });

    return filled;
  };

  /**
   * 填充 et-matching 连线题
   * 参考 WELearnHelper 项目的实现:直接注入 SVG line 元素并更新 AngularJS 数据
   * @param {Element} container - et-matching 容器元素
   * @returns {boolean} 是否成功填充
   */
  const fillEtMatching = (container) => {
    // 防止重复执行
    if (container.dataset.welearnGoProcessed === 'true') return false;

    const key = container.getAttribute('key');
    if (!key) {
      console.warn('[WeLearn-Go] fillEtMatching: 没有 key 属性');
      return false;
    }

    // 标记为已处理
    container.dataset.welearnGoProcessed = 'true';

    // 解析答案 key="1-2,2-5,3-4,4-3,5-1" 或 key="1-6,2-5,3-4,4-2,5-1,6-9,7-7,8-3,9-8,10-10"
    // 格式:左边索引-右边索引 (1-based)
    const pairs = key.split(',').map(p => p.trim()).filter(p => p);
    if (pairs.length === 0) {
      console.warn('[WeLearn-Go] fillEtMatching: 空的 key');
      return false;
    }

    console.info('[WeLearn-Go] fillEtMatching: 解析答案', { key, pairs });

    // 获取 AngularJS scope 和 matching 控制器
    const ownerWindow = container.ownerDocument?.defaultView || window;
    const angular = ownerWindow.angular;
    let scope = null;
    let matchingCtrl = null;

    if (angular) {
      try {
        scope = angular.element(container)?.scope();
        matchingCtrl = scope?.matching;
      } catch (e) {
        console.debug('[WeLearn-Go] fillEtMatching: 获取 scope 失败', e);
      }
    }

    if (!matchingCtrl) {
      console.warn('[WeLearn-Go] fillEtMatching: 未找到 matching 控制器');
      // 继续尝试 DOM 方式
    }

    // 获取圆点信息
    const leftCircles = Array.from(container.querySelectorAll('circle[data-circle="A"]'));
    const rightCircles = Array.from(container.querySelectorAll('circle[data-circle="B"]'));
    
    console.info('[WeLearn-Go] fillEtMatching: 圆点数量', { 
      left: leftCircles.length, 
      right: rightCircles.length 
    });

    if (leftCircles.length === 0 || rightCircles.length === 0) {
      console.warn('[WeLearn-Go] fillEtMatching: 未找到圆点');
      return false;
    }

    // ═══════════════════════════════════════════════════════════════
    // 方法1: 通过 AngularJS 控制器设置答案 (最可靠)
    // ═══════════════════════════════════════════════════════════════
    if (matchingCtrl) {
      try {
        // 初始化 answers 数组
        if (!matchingCtrl.answers || !Array.isArray(matchingCtrl.answers)) {
          matchingCtrl.answers = [];
        }
        
        // 确保数组足够长
        for (let i = 0; i < leftCircles.length; i++) {
          if (!matchingCtrl.answers[i]) {
            matchingCtrl.answers[i] = [];
          }
        }
        
        // 设置每条连线
        pairs.forEach(pair => {
          const parts = pair.split('-');
          if (parts.length !== 2) return;
          
          const leftIdx = parseInt(parts[0], 10) - 1;  // 1-based to 0-based
          const rightIdx = parseInt(parts[1], 10) - 1;
          
          if (leftIdx >= 0 && leftIdx < leftCircles.length && 
              rightIdx >= 0 && rightIdx < rightCircles.length) {
            // 确保不重复添加
            if (!matchingCtrl.answers[leftIdx].includes(rightIdx)) {
              matchingCtrl.answers[leftIdx].push(rightIdx);
            }
          }
        });
        
        console.info('[WeLearn-Go] fillEtMatching: 设置 answers', matchingCtrl.answers);
        
        // 触发 AngularJS 更新
        if (scope && scope.$apply) {
          try {
            scope.$apply();
          } catch (e) {
            // 可能已经在 digest 中
            scope.$evalAsync(() => {});
          }
        }
        
        // 短暂延迟后再次触发更新,确保 SVG 渲染
        setTimeout(() => {
          if (scope && scope.$digest) {
            try {
              scope.$digest();
            } catch (e) {}
          }
        }, 100);
        
        return true;
      } catch (e) {
        console.warn('[WeLearn-Go] fillEtMatching: AngularJS 方式失败', e);
      }
    }

    // ═══════════════════════════════════════════════════════════════
    // 方法2: 直接操作 SVG (备用方案)
    // ═══════════════════════════════════════════════════════════════
    const svg = container.querySelector('svg');
    let answersGroup = container.querySelector('g.answers');
    
    if (!svg) {
      console.warn('[WeLearn-Go] fillEtMatching: 未找到 SVG');
      return false;
    }

    // 如果没有 answers 组,创建一个
    if (!answersGroup) {
      answersGroup = document.createElementNS('http://www.w3.org/2000/svg', 'g');
      answersGroup.setAttribute('class', 'answers');
      svg.appendChild(answersGroup);
    }

    // 清除现有的线条(避免重复)
    const existingLines = answersGroup.querySelectorAll('line');
    existingLines.forEach(line => line.remove());

    // 画每条连线
    pairs.forEach(pair => {
      const parts = pair.split('-');
      if (parts.length !== 2) return;
      
      const leftIdx = parseInt(parts[0], 10) - 1;
      const rightIdx = parseInt(parts[1], 10) - 1;
      
      const leftCircle = leftCircles[leftIdx];
      const rightCircle = rightCircles[rightIdx];
      
      if (!leftCircle || !rightCircle) {
        console.warn('[WeLearn-Go] fillEtMatching: 未找到圆点', { leftIdx, rightIdx });
        return;
      }

      const x1 = leftCircle.getAttribute('cx');
      const y1 = leftCircle.getAttribute('cy');
      const x2 = rightCircle.getAttribute('cx');
      const y2 = rightCircle.getAttribute('cy');

      // 创建线条
      const line = document.createElementNS('http://www.w3.org/2000/svg', 'line');
      line.setAttribute('x1', x1);
      line.setAttribute('y1', y1);
      line.setAttribute('x2', x2);
      line.setAttribute('y2', y2);
      line.setAttribute('stroke', '#4a9'); // 绿色线条
      line.setAttribute('stroke-width', '2');
      
      answersGroup.appendChild(line);
      
      console.info('[WeLearn-Go] fillEtMatching: 画线', { leftIdx, rightIdx, x1, y1, x2, y2 });
    });

    // ═══════════════════════════════════════════════════════════════
    // 方法3: 模拟点击 (最后备用)
    // ═══════════════════════════════════════════════════════════════
    if (!matchingCtrl) {
      console.info('[WeLearn-Go] fillEtMatching: 尝试点击模拟');
      
      let clickIndex = 0;
      const doClick = () => {
        if (clickIndex >= pairs.length) return;
        
        const pair = pairs[clickIndex];
        const parts = pair.split('-');
        if (parts.length !== 2) {
          clickIndex++;
          setTimeout(doClick, 50);
          return;
        }
        
        const leftIdx = parseInt(parts[0], 10) - 1;
        const rightIdx = parseInt(parts[1], 10) - 1;
        
        const leftCircle = leftCircles[leftIdx];
        const rightCircle = rightCircles[rightIdx];
        
        if (leftCircle && rightCircle) {
          // 点击左边圆点
          leftCircle.dispatchEvent(new MouseEvent('click', {
            view: ownerWindow,
            bubbles: true,
            cancelable: true
          }));
          
          // 稍后点击右边圆点
          setTimeout(() => {
            rightCircle.dispatchEvent(new MouseEvent('click', {
              view: ownerWindow,
              bubbles: true,
              cancelable: true
            }));
            
            clickIndex++;
            setTimeout(doClick, 100);
          }, 150);
        } else {
          clickIndex++;
          setTimeout(doClick, 50);
        }
      };
      
      doClick();
    }

    return true;
  };

  /**
   * 填充 et-toggle 对话填空题(带视频/音频的对话练习)
   * 对话内容通常在 .lrc 或 .dialog 区域,填空位置有 et-blank 或 input 元素
   * @param {Element} container - et-toggle 容器元素
   * @param {Function} mutateAnswer - 答案变异函数
   * @returns {boolean} 是否有任何填充操作
   */
  const fillEtToggle = (container, mutateAnswer) => {
    let filled = false;

    // 查找对话区域中的 et-blank 填空
    const blanks = Array.from(container.querySelectorAll('et-blank'));
    blanks.forEach((blank) => {
      const changed = fillEtBlank(blank, mutateAnswer);
      filled = filled || changed;
    });

    // 查找 .lrc 区域中的填空(可能是 span 或 input)
    const lrcBlanks = Array.from(container.querySelectorAll('.lrc [contenteditable="true"], .lrc input[type="text"]'));
    lrcBlanks.forEach((input) => {
      const changed = fillGenericInput(input, mutateAnswer);
      filled = filled || changed;
    });

    // 查找对话区域中的填空
    const dialogBlanks = Array.from(container.querySelectorAll('.dialog [contenteditable="true"], .dialog input[type="text"]'));
    dialogBlanks.forEach((input) => {
      const changed = fillGenericInput(input, mutateAnswer);
      filled = filled || changed;
    });

    return filled;
  };

  /**
   * 从全局上下文中查找答案
   * @param {Element} element - 题目元素
   * @returns {string|null} 找到的答案或 null
   */
  const findAnswerFromGlobalContext = (element) => {
    const win = element.ownerDocument?.defaultView || window;
    const ids = [
      element.id,
      element.getAttribute('data-id'),
      element.getAttribute('data-question-id'),
      element.getAttribute('data-item-id'),
      element.closest('et-item')?.id
    ].filter(Boolean);

    if (ids.length === 0) return null;

    // 常见的全局数据源
    const dataSources = [
      win.courseData,
      win.pageData,
      win.activity,
      win.questionList,
      win.__INITIAL_STATE__,
      win.g_data
    ];

    for (const source of dataSources) {
      if (!source) continue;

      // 递归搜索答案
      const search = (obj, depth = 0) => {
        if (depth > 3 || !obj || typeof obj !== 'object') return null;

        // 检查当前对象是否包含 ID 和答案
        if (ids.some(id => obj.id == id || obj.questionId == id || obj.itemId == id)) {
          const possibleKeys = ['answer', 'key', 'correctAnswer', 'solution', 'rightAnswer'];
          for (const key of possibleKeys) {
            if (obj[key] !== undefined && obj[key] !== null && obj[key] !== '') {
              return String(obj[key]);
            }
          }
        }

        // 遍历数组或对象属性
        if (Array.isArray(obj)) {
          for (const item of obj) {
            const res = search(item, depth + 1);
            if (res) return res;
          }
        } else {
          for (const key in obj) {
            if (key === 'parent' || key === 'prev' || key === 'next') continue; // 避免循环引用
            const res = search(obj[key], depth + 1);
            if (res) return res;
          }
        }
        return null;
      };

      const result = search(source);
      if (result) {
        console.debug('[WeLearn-Go] findAnswerFromGlobalContext: 找到答案', result);
        return result;
      }
    }

    return null;
  };

  /**
   * 从解释文本中查找答案(针对 et-choice)
   * @param {Element} container - et-choice 容器
   * @param {Array<Element>} options - 选项元素数组
   * @returns {Element|null} 匹配的选项或 null
   */
  const findAnswerFromExplanation = (container, options) => {
    // 查找紧邻的 explanation 元素
    let explanationEl = container.nextElementSibling;
    if (!explanationEl || !explanationEl.classList.contains('explanation')) {
      // 尝试在父级查找
      const parent = container.parentElement;
      if (parent) {
        const explanationInParent = parent.querySelector(`.explanation[visible-on-key]`);
        // 确保它属于当前题目(简单的位置判断)
        if (explanationInParent && explanationInParent.compareDocumentPosition(container) & Node.DOCUMENT_POSITION_PRECEDING) {
           // explanation 在 container 之后
           explanationEl = explanationInParent;
        }
      }
    }

    if (!explanationEl) return null;

    const explanationText = normalizeText(explanationEl.textContent);
    if (!explanationText) return null;

    // 1. 寻找最长完整子串匹配
    let longestSubstringMatch = null;
    let longestLen = 0;
    
    options.forEach(opt => {
      const optText = normalizeText(opt.textContent);
      if (optText && explanationText.includes(optText)) {
        if (optText.length > longestLen) {
          longestLen = optText.length;
          longestSubstringMatch = opt;
        }
      }
    });
    
    if (longestSubstringMatch) {
      console.debug('[WeLearn-Go] findAnswerFromExplanation: 找到完整子串匹配', longestSubstringMatch.textContent);
      return longestSubstringMatch;
    }
    
    // 2. 如果没有完整匹配,尝试单词覆盖率
    let bestFuzzyMatch = null;
    let bestFuzzyScore = 0;
    
    options.forEach(opt => {
      const optText = normalizeText(opt.textContent);
      const stopWords = ['THE', 'A', 'AN', 'IN', 'ON', 'AT', 'TO', 'OF', 'FOR', 'AND', 'BUT', 'OR', 'IS', 'ARE', 'WAS', 'WERE', 'IT', 'THIS', 'THAT', 'HE', 'SHE', 'THEY'];
      const words = optText.split(/[^A-Z0-9]+/).filter(w => w.length > 2 && !stopWords.includes(w));
      
      if (words.length < 2) return; // 单词太少不准确

      let matchCount = 0;
      words.forEach(w => {
        // 简单的单词包含检查
        if (explanationText.includes(w)) matchCount++;
      });

      const score = matchCount / words.length;
      if (score > 0.75 && score > bestFuzzyScore) {
        bestFuzzyScore = score;
        bestFuzzyMatch = opt;
      }
    });
    
    if (bestFuzzyMatch) {
      console.debug('[WeLearn-Go] findAnswerFromExplanation: 找到模糊匹配', bestFuzzyMatch.textContent, bestFuzzyScore);
    }
    
    return bestFuzzyMatch;
  };

  /**
   * 填充 et-choice 选择题(综合实现)
   * 
   * 核心原理:et-choice 元素可能有 key 属性存储正确答案
   * 也可能需要从 AngularJS scope 或 .key 类获取答案
   * 选项可以是 li 或 span 形式
   * 
   * 答案来源(按优先级):
   * 1. et-choice 的 key 属性 - 如 "A", "B", "1", "2" 或多选 "A,B"
   * 2. AngularJS scope 的 isKey() 方法
   * 3. 已显示的 .key 类
   * 4. span.key 答案提示文本
   * 
   * @param {Element} container - et-choice 容器元素
   * @returns {boolean} 是否成功填充
   */
  const fillEtChoice = (container) => {
    console.log('[WeLearn-Go] fillEtChoice: 开始处理');
    
    // 跳过重复元素(WELearnHelper 的 isRepeat 逻辑简化版)
    if (container.closest('et-web-only')) {
      console.log('[WeLearn-Go] fillEtChoice: 在 et-web-only 中,跳过');
      return false;
    }
    
    // 检查是否已经有选中的选项(如果已选中正确答案则跳过)
    const alreadyChosen = container.querySelector('li.chosen, li.active, li.selected');
    if (alreadyChosen) {
      console.log('[WeLearn-Go] fillEtChoice: 已有选中选项,跳过');
      return false;
    }
    
    // ====== 1. 查找选项元素 ======
    let options = Array.from(container.querySelectorAll('li'));
    let useSpan = false;
    
    if (options.length === 0) {
      options = Array.from(container.querySelectorAll('span[ng-click*="select"]'));
      useSpan = true;
    }
    
    if (options.length === 0) {
      // 尝试从 .wrapper 内查找
      const wrapper = container.querySelector('.wrapper');
      if (wrapper) {
        options = Array.from(wrapper.querySelectorAll('li'));
        if (options.length === 0) {
          options = Array.from(wrapper.querySelectorAll('span[ng-click*="select"]'));
          useSpan = true;
        }
      }
    }
    
    if (options.length === 0) {
      console.warn('[WeLearn-Go] fillEtChoice: 没有找到选项元素');
      return false;
    }
    
    console.log('[WeLearn-Go] fillEtChoice: 选项类型:', useSpan ? 'span' : 'li', '数量:', options.length);
    
    // ====== 2. 获取答案 ======
    let targetOption = null;
    let targetIdx = -1;
    let answerSource = '';  // 记录答案来源:'key', 'scope', 'explanation', 'fuzzy' 等
    let isReliable = true;  // 答案是否可靠(标准答案 vs 解析推断)
    
    // 方法1: 从 key 属性获取答案
    const keyAttr = container.getAttribute('key');
    if (keyAttr) {
      console.log('[WeLearn-Go] fillEtChoice: 发现 key 属性:', keyAttr);
      
      const answerKeys = keyAttr.split(',').map(k => k.trim());
      
      for (const answerKey of answerKeys) {
        let idx = -1;
        
        if (/^[A-Za-z]$/.test(answerKey)) {
          idx = answerKey.toUpperCase().charCodeAt(0) - 65;
        } else if (/^\d+$/.test(answerKey)) {
          idx = parseInt(answerKey, 10) - 1;
        }
        
        if (idx >= 0 && idx < options.length) {
          targetOption = options[idx];
          targetIdx = idx;
          console.log('[WeLearn-Go] fillEtChoice: 通过 key 属性找到答案,索引:', idx);
          answerSource = 'key属性';
          isReliable = true;
          break;
        }
      }
    }
    
    // 方法2: 通过 AngularJS scope 获取答案 (详细调试版)
    if (!targetOption) {
      try {
        const scopeDoc = container.ownerDocument?.defaultView || window;
        const angular = scopeDoc.angular;
        
        if (angular) {
          console.log('[WeLearn-Go] fillEtChoice: 尝试 AngularJS 方法');
          
          // 获取 scope - 尝试多种元素
          const elementsToTry = [container];
          const wrapper = container.querySelector('.wrapper');
          if (wrapper) elementsToTry.push(wrapper);
          if (options[0]) elementsToTry.push(options[0]);
          
          let scope = null;
          let controller = null;
          
          for (const el of elementsToTry) {
            scope = angular.element(el)?.scope();
            if (scope) {
              controller = scope.choice || scope.$ctrl || scope.vm;
              if (controller) break;
            }
          }
          
          if (scope) {
            console.log('[WeLearn-Go] fillEtChoice: 获取到 scope');
            
            // ★★★ 详细调试:打印 scope 中所有非 $ 开头的属性 ★★★
            const scopeKeys = Object.keys(scope).filter(k => !k.startsWith('$') && !k.startsWith('_'));
            console.log('[WeLearn-Go] fillEtChoice: scope 属性:', scopeKeys);
            
            // 特别查看 choice 对象
            if (scope.choice) {
              const choiceKeys = Object.keys(scope.choice).filter(k => !k.startsWith('$'));
              console.log('[WeLearn-Go] fillEtChoice: choice 属性:', choiceKeys);
              
              // 打印所有 choice 的值(调试用)
              for (const k of choiceKeys) {
                const v = scope.choice[k];
                if (typeof v !== 'function') {
                  console.log(`[WeLearn-Go] choice.${k} =`, v);
                } else {
                  console.log(`[WeLearn-Go] choice.${k} = [Function]`);
                }
              }
              
              controller = scope.choice;
            }
          }
          
          if (controller) {
            console.log('[WeLearn-Go] fillEtChoice: 找到 controller,keys:', Object.keys(controller).filter(k => !k.startsWith('$')));
            
            // ★★★ 核心:尝试调用 isKey 方法 ★★★
            if (typeof controller.isKey === 'function') {
              console.log('[WeLearn-Go] fillEtChoice: 找到 isKey 方法,遍历选项');
              for (let i = 0; i < options.length; i++) {
                try {
                  const isKey = controller.isKey(i);
                  console.log(`[WeLearn-Go] fillEtChoice: isKey(${i}) = ${isKey}`);
                  if (isKey) {
                    targetOption = options[i];
                    targetIdx = i;
                    console.log('[WeLearn-Go] fillEtChoice: 通过 isKey 找到答案,索引:', i);
                    answerSource = 'AngularJS isKey';
                    isReliable = true;
                    break;
                  }
                } catch (e) {
                  console.debug('[WeLearn-Go] fillEtChoice: isKey 调用失败', e);
                }
              }
            }
            
            // ★★★ 核心:检查 data.key 属性 ★★★
            if (!targetOption && controller.data) {
              console.log('[WeLearn-Go] fillEtChoice: controller.data 存在');
              if (controller.data.key !== undefined) {
                let idx = controller.data.key;
                console.log('[WeLearn-Go] fillEtChoice: controller.data.key =', idx, typeof idx);
                if (typeof idx === 'number') {
                  // key 可能是 0-based 或 1-based
                  const try0 = idx;
                  const try1 = idx - 1;
                  if (try0 >= 0 && try0 < options.length) {
                    targetOption = options[try0];
                    targetIdx = try0;
                    console.log('[WeLearn-Go] fillEtChoice: 通过 data.key (0-based) 找到答案,索引:', try0);
                    answerSource = 'AngularJS data.key';
                    isReliable = true;
                  } else if (try1 >= 0 && try1 < options.length) {
                    targetOption = options[try1];
                    targetIdx = try1;
                    console.log('[WeLearn-Go] fillEtChoice: 通过 data.key (1-based) 找到答案,索引:', try1);
                    answerSource = 'AngularJS data.key';
                    isReliable = true;
                  }
                }
              }
              // 打印 data 的其他属性
              const dataKeys = Object.keys(controller.data);
              console.log('[WeLearn-Go] fillEtChoice: controller.data 属性:', dataKeys);
            }
            
            // ★★★ 核心:检查 key 属性(字符串或数字) ★★★
            if (!targetOption && controller.key !== undefined) {
              let idx = controller.key;
              console.log('[WeLearn-Go] fillEtChoice: controller.key =', idx, typeof idx);
              if (typeof idx === 'number') {
                if (idx >= 0 && idx < options.length) {
                  targetOption = options[idx];
                  targetIdx = idx;
                } else if (idx - 1 >= 0 && idx - 1 < options.length) {
                  targetOption = options[idx - 1];
                  targetIdx = idx - 1;
                }
              } else if (typeof idx === 'string') {
                // 可能是字母 A/B/C/D
                if (/^[A-Da-d]$/.test(idx)) {
                  const letterIdx = idx.toUpperCase().charCodeAt(0) - 65;
                  if (letterIdx >= 0 && letterIdx < options.length) {
                    targetOption = options[letterIdx];
                    targetIdx = letterIdx;
                  }
                } else if (/^\d+$/.test(idx)) {
                  const numIdx = parseInt(idx, 10) - 1;
                  if (numIdx >= 0 && numIdx < options.length) {
                    targetOption = options[numIdx];
                    targetIdx = numIdx;
                  }
                }
              }
              if (targetOption) {
                console.log('[WeLearn-Go] fillEtChoice: 通过 controller.key 找到答案,索引:', targetIdx);
              }
            }
            
            // ★★★ 核心:检查 std_answer 或 answer 属性 ★★★
            if (!targetOption) {
              const answerProps = ['std_answer', 'answer', 'correctAnswer', 'correct', 'correctIndex'];
              for (const prop of answerProps) {
                if (controller[prop] !== undefined) {
                  const val = controller[prop];
                  console.log(`[WeLearn-Go] fillEtChoice: controller.${prop} =`, val, typeof val);
                  let idx = -1;
                  if (typeof val === 'number') {
                    idx = val >= 1 && val <= options.length ? val - 1 : val;
                  } else if (typeof val === 'string' && /^[A-Da-d]$/.test(val)) {
                    idx = val.toUpperCase().charCodeAt(0) - 65;
                  } else if (typeof val === 'string' && /^\d+$/.test(val)) {
                    idx = parseInt(val, 10) - 1;
                  }
                  if (idx >= 0 && idx < options.length) {
                    targetOption = options[idx];
                    targetIdx = idx;
                    console.log(`[WeLearn-Go] fillEtChoice: 通过 ${prop} 找到答案,索引:`, idx);
                    break;
                  }
                }
              }
            }
          } else {
            console.log('[WeLearn-Go] fillEtChoice: 未找到 controller/choice');
            // 打印 scope 内容帮助调试
            if (scope) {
              console.log('[WeLearn-Go] fillEtChoice: scope 内容:', 
                Object.keys(scope).filter(k => !k.startsWith('$') && !k.startsWith('_')).slice(0, 20));
            }
          }
        } else {
          console.log('[WeLearn-Go] fillEtChoice: 未找到 angular');
        }
      } catch (e) {
        console.debug('[WeLearn-Go] fillEtChoice: AngularJS 访问失败', e);
      }
    }
    
    // 方法3: 查找已有 .key 类的选项
    if (!targetOption) {
      targetOption = options.find((opt, i) => {
        if (opt.classList.contains('key')) {
          targetIdx = i;
          return true;
        }
        return false;
      });
      if (targetOption) {
        console.log('[WeLearn-Go] fillEtChoice: 通过 .key 类找到答案,索引:', targetIdx);
        answerSource = 'CSS .key类';
        isReliable = true;
      }
    }
    
    // 方法4: 从父级 et-item 中查找 span.key 答案提示
    if (!targetOption) {
      const etItem = container.closest('et-item');
      if (etItem) {
        const keySpan = etItem.querySelector('span.key:not([ng-click])');
        if (keySpan) {
          const keyText = keySpan.textContent?.trim().toLowerCase();
          console.log('[WeLearn-Go] fillEtChoice: 找到 span.key 答案:', keyText);
          
          targetOption = options.find((opt, i) => {
            const optText = opt.textContent?.trim().toLowerCase();
            if (optText === keyText || optText.includes(keyText)) {
              targetIdx = i;
              return true;
            }
            return false;
          });
          
          if (targetOption) {
            console.log('[WeLearn-Go] fillEtChoice: 通过 span.key 文本匹配找到答案');
          }
        }
      }
    }
    
    // 方法5: 从选项的 ng-class 解析 isKey
    if (!targetOption) {
      for (let i = 0; i < options.length; i++) {
        const opt = options[i];
        const ngClass = opt.getAttribute('ng-class') || '';
        const keyMatch = ngClass.match(/key:\s*choice\.isKey\((\d+)\)/);
        
        if (keyMatch) {
          const expectedIdx = parseInt(keyMatch[1], 10);
          try {
            const scopeDoc = container.ownerDocument?.defaultView || window;
            const angular = scopeDoc.angular;
            const scope = angular?.element(opt)?.scope();
            
            if (scope?.choice?.isKey) {
              const isKey = scope.choice.isKey(expectedIdx);
              if (isKey) {
                targetOption = opt;
                targetIdx = i;
                console.log('[WeLearn-Go] fillEtChoice: 通过 ng-class isKey 找到答案,索引:', i);
                break;
              }
            }
          } catch (e) { /* 忽略 */ }
        }
      }
    }
    
    // 方法6: ★★★ 从解释文本 (p.explanation) 中提取答案 ★★★
    // 解释文本通常紧跟在 et-choice 后面,格式如:"正确答案是B" 或 "故C是正确答案"
    if (!targetOption) {
      // 查找紧邻的 p.explanation 元素
      // 注意:explanation 必须是当前 et-choice 的直接后继,不能跨越其他 et-choice
      let explanationEl = null;
      let sibling = container.nextElementSibling;
      
      while (sibling) {
        // 如果遇到另一个 et-choice,停止搜索
        if (sibling.tagName?.toLowerCase() === 'et-choice') {
          break;
        }
        // 找到 explanation
        if (sibling.classList?.contains('explanation')) {
          explanationEl = sibling;
          break;
        }
        sibling = sibling.nextElementSibling;
      }
      
      if (explanationEl) {
        const explanationText = explanationEl.textContent || '';
        // 打印更多文本内容用于调试
        console.log('[WeLearn-Go] fillEtChoice: 找到解释文本 (长度' + explanationText.length + '):', 
          explanationText.length > 200 ? explanationText.substring(0, 100) + '...' + explanationText.substring(explanationText.length - 100) : explanationText);
        
        // 匹配多种答案格式:
        // "正确答案是B" "正确答案是 B" "正确答案为B"
        // "故C是正确答案" "故 C 是正确答案" "故C项为正确答案"
        // "答案是A" "答案为A" "选A" "选择A"
        // "所以D项并非..." (反向选择题,选错误项)
        // "The answer is B" "Answer: C"
        // "C项表述符合" "只有C项与新闻相符"
        const patterns = [
          /正确答案[是为]?\s*([A-Da-d])/,
          /故\s*([A-Da-d])\s*项?[是为]?正确答案/,  // "故C项为正确答案"
          /([A-Da-d])\s*项?[是为]正确答案/,        // "C项为正确答案"
          /([A-Da-d])\s*项?表述符合/,              // ★新增:"C项表述符合"
          /([A-Da-d])\s*项?与新闻相符/,            // ★新增:"C项与新闻相符"
          /([A-Da-d])\s*项?符合/,                  // ★新增:"C项符合"
          /只有\s*([A-Da-d])\s*项?/,               // ★新增:"只有C项"
          /答案[是为]?\s*([A-Da-d])/,
          /选[择]?\s*([A-Da-d])/,
          /[Aa]nswer[:\s]+([A-Da-d])/i,
          /([A-Da-d])\s*[是为]正确/,
          /([A-Da-d])\s*项?正确/,
          // 反向选择题格式 "所以D项并非" "D项不是" 等
          /所以\s*([A-Da-d])\s*项?/,
          /([A-Da-d])\s*项?并非/,
          /([A-Da-d])\s*项?不是/,
          /([A-Da-d])\s*项?错误/,
          /排除\s*([A-Da-d])/,
        ];
        
        for (const pattern of patterns) {
          const match = explanationText.match(pattern);
          if (match) {
            const answerLetter = match[1].toUpperCase();
            const idx = answerLetter.charCodeAt(0) - 65; // A=0, B=1, C=2, D=3
            
            if (idx >= 0 && idx < options.length) {
              targetOption = options[idx];
              targetIdx = idx;
              console.log('[WeLearn-Go] fillEtChoice: 从解释文本提取到答案:', answerLetter, '-> 索引:', idx);
              answerSource = '解释文本正则匹配';
              isReliable = false;  // 解析推断,可能有误
              break;
            }
          }
        }
        
        // ★★★ 方法6a-2: 中文解析末尾字母提取 ★★★
        // 规则:如果解释文本主要是中文,且末尾有单独的字母 A/B/C/D,则该字母就是答案
        // 例如:"...C项表述符合新闻的主旨大意。C" -> 答案是 C
        // 或者:"...综上所述,答案选 B。" -> 答案是 B
        if (!targetOption) {
          // 检查是否主要是中文(包含中文字符)
          const hasChinese = /[\u4e00-\u9fa5]/.test(explanationText);
          
          if (hasChinese) {
            // 提取文本末尾的字母(去除标点和空格后)
            // 匹配模式:文本结尾的 A/B/C/D,可能前面有标点或空格
            const endPatterns = [
              /[。.,,;;!!??\s]+([A-Da-d])\s*[。.]*\s*$/,    // "...主旨大意。C" 或 "...答案选 B。"
              /([A-Da-d])\s*[。.]*\s*$/,                        // 直接以字母结尾
              /选\s*([A-Da-d])\s*[。.]*\s*$/,                   // "选C" 结尾
              /是\s*([A-Da-d])\s*[。.]*\s*$/,                   // "是C" 结尾
              /为\s*([A-Da-d])\s*[。.]*\s*$/,                   // "为C" 结尾
            ];
            
            for (const pattern of endPatterns) {
              const match = explanationText.match(pattern);
              if (match) {
                const answerLetter = match[1].toUpperCase();
                const idx = answerLetter.charCodeAt(0) - 65;
                
                if (idx >= 0 && idx < options.length) {
                  targetOption = options[idx];
                  targetIdx = idx;
                  console.log('[WeLearn-Go] fillEtChoice: 从解释文本末尾提取到答案:', answerLetter, '-> 索引:', idx);
                  answerSource = '解释文本末尾字母';
                  isReliable = false;  // 解析推断,可能有误
                  break;
                }
              }
            }
            
            // 如果上面的模式没匹配到,尝试找最后一个出现的 A/B/C/D
            if (!targetOption) {
              // 找文本中所有的 A/B/C/D(独立出现,不是单词的一部分)
              const letterMatches = explanationText.match(/(?:^|[^a-zA-Z])([A-Da-d])(?:[^a-zA-Z]|$)/g);
              if (letterMatches && letterMatches.length > 0) {
                // 取最后一个匹配
                const lastMatch = letterMatches[letterMatches.length - 1];
                const letterMatch = lastMatch.match(/[A-Da-d]/);
                if (letterMatch) {
                  const answerLetter = letterMatch[0].toUpperCase();
                  const idx = answerLetter.charCodeAt(0) - 65;
                  
                  if (idx >= 0 && idx < options.length) {
                    targetOption = options[idx];
                    targetIdx = idx;
                    console.log('[WeLearn-Go] fillEtChoice: 从解释文本最后一个字母提取答案:', answerLetter, '-> 索引:', idx);
                    answerSource = '解释文本最后字母';
                    isReliable = false;  // 解析推断,可能有误
                  }
                }
              }
            }
          }
        }
        
        // ★★★ 方法6b: 从解释文本中的数值与选项进行匹配 ★★★
        // 例如: 解释 "1.1 degrees Celsius" 匹配选项 "1.1°C"
        // 或者: 解释 "over 620,000" 匹配选项 "More than 620,000"
        // 注意: 只在选项本身包含数值时才启用数值匹配
        if (!targetOption) {
          // 先检查选项是否主要是数值型选项
          const optionTexts = options.map(opt => opt.textContent?.trim() || '');
          const numericOptionCount = optionTexts.filter(t => /^\d|^[\$€£¥]?\d|^[<>≤≥]?\s*\d/.test(t) || 
            /\d+[%°]/.test(t) || /\d+\/\d+/.test(t)).length;
          
          // 只有当至少一半选项是数值型时,才使用数值匹配
          const shouldUseNumericMatch = numericOptionCount >= options.length / 2;
          console.log('[WeLearn-Go] fillEtChoice: 数值型选项数量:', numericOptionCount, '/', options.length, 
            shouldUseNumericMatch ? '-> 启用数值匹配' : '-> 跳过数值匹配');
          
          if (shouldUseNumericMatch) {
            console.log('[WeLearn-Go] fillEtChoice: 尝试数值匹配');
            
            // ═══════════════════════════════════════════════════════════════
            // ★★★ 完整的文本标准化规则系统 ★★★
            // ═══════════════════════════════════════════════════════════════
            const normalizeText = (text) => {
              let n = text.toLowerCase();
              
              // ─────────────────────────────────────────────────────────────
              // 规则1: 英文小数点表达 "point" -> "."
              // ─────────────────────────────────────────────────────────────
              n = n.replace(/\bpoint\s+/g, '.');
              
              // ─────────────────────────────────────────────────────────────
              // 规则2: 英文复合数字 (21-99)
              // ─────────────────────────────────────────────────────────────
              const compoundNumbers = {
                'twenty': 20, 'thirty': 30, 'forty': 40, 'fifty': 50,
                'sixty': 60, 'seventy': 70, 'eighty': 80, 'ninety': 90
              };
              const unitNumbers = {
                'one': 1, 'two': 2, 'three': 3, 'four': 4, 'five': 5,
                'six': 6, 'seven': 7, 'eight': 8, 'nine': 9
              };
              
              // 处理 "eighty-eight", "twenty one" 等
              for (const [tens, tensVal] of Object.entries(compoundNumbers)) {
                for (const [unit, unitVal] of Object.entries(unitNumbers)) {
                  const combined = tensVal + unitVal;
                  n = n.replace(new RegExp(`\\b${tens}[\\s-]${unit}\\b`, 'g'), String(combined));
                }
              }
              
              // ─────────────────────────────────────────────────────────────
              // 规则3: 英文基础数字 (0-19, 整十, 大数)
              // ─────────────────────────────────────────────────────────────
              const basicNumbers = {
                'zero': '0', 'one': '1', 'two': '2', 'three': '3', 'four': '4',
                'five': '5', 'six': '6', 'seven': '7', 'eight': '8', 'nine': '9',
                'ten': '10', 'eleven': '11', 'twelve': '12', 'thirteen': '13',
                'fourteen': '14', 'fifteen': '15', 'sixteen': '16', 'seventeen': '17',
                'eighteen': '18', 'nineteen': '19',
                'twenty': '20', 'thirty': '30', 'forty': '40', 'fifty': '50',
                'sixty': '60', 'seventy': '70', 'eighty': '80', 'ninety': '90',
                'hundred': '00', 'thousand': '000', 'million': '000000', 'billion': '000000000'
              };
              
              for (const [word, num] of Object.entries(basicNumbers)) {
                n = n.replace(new RegExp(`\\b${word}\\b`, 'g'), num);
              }
              
              // ─────────────────────────────────────────────────────────────
              // 规则4: 中文数字
              // ─────────────────────────────────────────────────────────────
              const chineseNumbers = {
                '零': '0', '一': '1', '二': '2', '两': '2', '三': '3', '四': '4',
                '五': '5', '六': '6', '七': '7', '八': '8', '九': '9', '十': '10',
                '百': '00', '千': '000', '万': '0000', '亿': '00000000'
              };
              
              for (const [cn, num] of Object.entries(chineseNumbers)) {
                n = n.replace(new RegExp(cn, 'g'), num);
              }
              
              // ─────────────────────────────────────────────────────────────
              // 规则5: 序数词
              // ─────────────────────────────────────────────────────────────
              const ordinals = {
                'first': '1', 'second': '2', 'third': '3', 'fourth': '4', 'fifth': '5',
                'sixth': '6', 'seventh': '7', 'eighth': '8', 'ninth': '9', 'tenth': '10',
                '第一': '1', '第二': '2', '第三': '3', '第四': '4', '第五': '5'
              };
              
              for (const [ord, num] of Object.entries(ordinals)) {
                n = n.replace(new RegExp(`\\b${ord}\\b`, 'gi'), num);
              }
              
              // ─────────────────────────────────────────────────────────────
              // 规则6: 分数表达
              // ─────────────────────────────────────────────────────────────
              const fractions = {
                'quarter': '1/4', 'half': '1/2', 'third': '1/3',
                'one quarter': '1/4', 'one half': '1/2', 'one third': '1/3',
                'two thirds': '2/3', 'three quarters': '3/4',
                '四分之一': '1/4', '二分之一': '1/2', '三分之一': '1/3',
                '三分之二': '2/3', '四分之三': '3/4'
              };
              
              for (const [frac, num] of Object.entries(fractions)) {
                n = n.replace(new RegExp(frac, 'gi'), num);
              }
              
              // ─────────────────────────────────────────────────────────────
              // 规则7: 百分比表达
              // ─────────────────────────────────────────────────────────────
              n = n.replace(/\s*percent\b/gi, '%');
              n = n.replace(/\s*per\s*cent\b/gi, '%');
              n = n.replace(/%/g, '%');
              n = n.replace(/百分之(\d+)/g, '$1%');
              
              // ─────────────────────────────────────────────────────────────
              // 规则8: 温度表达
              // ─────────────────────────────────────────────────────────────
              n = n.replace(/(\d+\.?\d*)\s*degrees?\s*celsius/gi, '$1°C');
              n = n.replace(/(\d+\.?\d*)\s*degrees?\s*fahrenheit/gi, '$1°F');
              n = n.replace(/(\d+\.?\d*)\s*degrees?\s*centigrade/gi, '$1°C');
              n = n.replace(/degrees?\s*celsius/gi, '°C');
              n = n.replace(/degrees?\s*fahrenheit/gi, '°F');
              n = n.replace(/摄氏(\d+)/g, '$1°C');
              n = n.replace(/华氏(\d+)/g, '$1°F');
              n = n.replace(/(\d+)\s*摄氏度/g, '$1°C');
              n = n.replace(/(\d+)\s*华氏度/g, '$1°F');
              
              // ─────────────────────────────────────────────────────────────
              // 规则9: 货币表达
              // ─────────────────────────────────────────────────────────────
              n = n.replace(/\$\s*(\d)/g, '$$$1');  // 移除 $ 后的空格
              n = n.replace(/(\d+\.?\d*)\s*dollars?/gi, '$$$1');
              n = n.replace(/(\d+\.?\d*)\s*euros?/gi, '€$1');
              n = n.replace(/(\d+\.?\d*)\s*pounds?/gi, '£$1');
              n = n.replace(/(\d+\.?\d*)\s*元/g, '¥$1');
              n = n.replace(/(\d+\.?\d*)\s*美元/g, '$$$1');
              
              // ─────────────────────────────────────────────────────────────
              // 规则10: 数量级表达
              // ─────────────────────────────────────────────────────────────
              n = n.replace(/(\d+\.?\d*)\s*million/gi, (m, p1) => String(parseFloat(p1) * 1000000));
              n = n.replace(/(\d+\.?\d*)\s*billion/gi, (m, p1) => String(parseFloat(p1) * 1000000000));
              n = n.replace(/(\d+\.?\d*)\s*thousand/gi, (m, p1) => String(parseFloat(p1) * 1000));
              
              // ─────────────────────────────────────────────────────────────
              // 规则11: 比较词标准化
              // ─────────────────────────────────────────────────────────────
              n = n.replace(/\bmore\s+than\b/gi, '>');
              n = n.replace(/\bover\b/gi, '>');
              n = n.replace(/\babove\b/gi, '>');
              n = n.replace(/\bexceeds?\b/gi, '>');
              n = n.replace(/\bless\s+than\b/gi, '<');
              n = n.replace(/\bunder\b/gi, '<');
              n = n.replace(/\bbelow\b/gi, '<');
              n = n.replace(/\bfewer\s+than\b/gi, '<');
              n = n.replace(/\babout\b/gi, '≈');
              n = n.replace(/\baround\b/gi, '≈');
              n = n.replace(/\bapproximately\b/gi, '≈');
              n = n.replace(/\bnearly\b/gi, '≈');
              n = n.replace(/\balmost\b/gi, '≈');
              n = n.replace(/\bat\s+least\b/gi, '≥');
              n = n.replace(/\bat\s+most\b/gi, '≤');
              n = n.replace(/\bup\s+to\b/gi, '≤');
              n = n.replace(/超过/g, '>');
              n = n.replace(/多于/g, '>');
              n = n.replace(/大于/g, '>');
              n = n.replace(/少于/g, '<');
              n = n.replace(/小于/g, '<');
              n = n.replace(/低于/g, '<');
              n = n.replace(/大约/g, '≈');
              n = n.replace(/约/g, '≈');
              n = n.replace(/近/g, '≈');
              n = n.replace(/至少/g, '≥');
              n = n.replace(/最多/g, '≤');
              
              // ─────────────────────────────────────────────────────────────
              // 规则12: 时间表达
              // ─────────────────────────────────────────────────────────────
              n = n.replace(/(\d+)\s*years?\s*old/gi, '$1岁');
              n = n.replace(/(\d+)\s*年/g, '$1年');
              n = n.replace(/(\d+)\s*months?/gi, '$1月');
              n = n.replace(/(\d+)\s*weeks?/gi, '$1周');
              n = n.replace(/(\d+)\s*days?/gi, '$1天');
              n = n.replace(/(\d+)\s*hours?/gi, '$1小时');
              n = n.replace(/(\d+)\s*minutes?/gi, '$1分钟');
              n = n.replace(/(\d+)\s*seconds?/gi, '$1秒');
              n = n.replace(/century/gi, '世纪');
              n = n.replace(/centuries/gi, '世纪');
              n = n.replace(/decade/gi, '十年');
              n = n.replace(/decades/gi, '十年');
              
              // ─────────────────────────────────────────────────────────────
              // 规则13: 清理格式
              // ─────────────────────────────────────────────────────────────
              n = n.replace(/,/g, '');           // 移除千位分隔符
              n = n.replace(/(\d+)\s*\.\s*(\d+)/g, '$1.$2');  // 修复小数点空格
              n = n.replace(/\s+/g, ' ');        // 合并多余空格
              
              return n.trim();
            };
            
            const normalizedExplanation = normalizeText(explanationText);
            console.log('[WeLearn-Go] fillEtChoice: 标准化解释文本:', normalizedExplanation.substring(0, 150));
            
            // ═══════════════════════════════════════════════════════════════
            // ★★★ 数值提取规则 ★★★
            // ═══════════════════════════════════════════════════════════════
            const extractPatterns = [
              { name: '温度', pattern: /(\d+\.?\d*)°[CF]/gi },
              { name: '百分比', pattern: /(\d+\.?\d*)\s*%/g },
              { name: '分数', pattern: /(\d+)\s*\/\s*(\d+)/g },
              { name: '货币', pattern: /[$€£¥]\s*(\d+\.?\d*)/g },
              { name: '比较数值', pattern: /[><=≈≥≤]\s*(\d+\.?\d*)/g },
              { name: '普通数字', pattern: /\b(\d+\.?\d*)\b/g },
            ];
            
            const extractedValues = [];
            for (const { name, pattern } of extractPatterns) {
              let match;
              const p = new RegExp(pattern.source, pattern.flags);
              while ((match = p.exec(normalizedExplanation)) !== null) {
                extractedValues.push({ type: name, value: match[0].toLowerCase(), raw: match[0] });
              }
            }
            console.log('[WeLearn-Go] fillEtChoice: 提取的数值:', extractedValues.map(v => v.value));
            
            // ═══════════════════════════════════════════════════════════════
            // ★★★ 分数与百分比等价映射 ★★★
            // ═══════════════════════════════════════════════════════════════
            const fractionToPercent = {
              '1/4': 25, '1/2': 50, '1/3': 33.33, '2/3': 66.67, '3/4': 75,
              '1/5': 20, '2/5': 40, '3/5': 60, '4/5': 80,
              '1/10': 10, '1/8': 12.5, '1/6': 16.67, '3/10': 30, '7/10': 70
            };
            
            // ═══════════════════════════════════════════════════════════════
            // ★★★ 单位标准化映射表 ★★★
            // ═══════════════════════════════════════════════════════════════
            const unitMappings = {
              // 温度
              '°C': ['°c', 'celsius', '摄氏', '摄氏度'],
              '°F': ['°f', 'fahrenheit', '华氏', '华氏度'],
              // 长度
              'km': ['kilometer', 'kilometers', 'kilometre', 'kilometres', '公里', '千米'],
              'm': ['meter', 'meters', 'metre', 'metres', '米'],
              'cm': ['centimeter', 'centimeters', 'centimetre', 'centimetres', '厘米'],
              'mm': ['millimeter', 'millimeters', 'millimetre', 'millimetres', '毫米'],
              'mi': ['mile', 'miles', '英里'],
              'ft': ['foot', 'feet', '英尺'],
              'in': ['inch', 'inches', '英寸'],
              // 重量
              'kg': ['kilogram', 'kilograms', '公斤', '千克'],
              'g': ['gram', 'grams', '克'],
              'mg': ['milligram', 'milligrams', '毫克'],
              'lb': ['pound', 'pounds', '磅'],
              'oz': ['ounce', 'ounces', '盎司'],
              't': ['ton', 'tons', 'tonne', 'tonnes', '吨'],
              // 体积/容量
              'L': ['liter', 'liters', 'litre', 'litres', '升'],
              'mL': ['milliliter', 'milliliters', 'millilitre', 'millilitres', '毫升'],
              'gal': ['gallon', 'gallons', '加仑'],
              // 面积
              'km²': ['square kilometer', 'square kilometers', 'sq km', '平方公里'],
              'm²': ['square meter', 'square meters', 'sq m', '平方米'],
              // 速度
              'km/h': ['kilometers per hour', 'kph', '公里/小时', '千米每小时'],
              'mph': ['miles per hour', '英里/小时'],
              'm/s': ['meters per second', '米/秒'],
              // 时间
              'h': ['hour', 'hours', '小时', '时'],
              'min': ['minute', 'minutes', '分钟', '分'],
              's': ['second', 'seconds', '秒'],
              'yr': ['year', 'years', '年'],
              'mo': ['month', 'months', '月'],
              'wk': ['week', 'weeks', '周'],
              'd': ['day', 'days', '天', '日'],
              // 人口/数量
              'people': ['人', '人口', 'persons'],
              'billion': ['十亿', 'bn', 'b'],
              'million': ['百万', 'm', 'mn'],
              'thousand': ['千', 'k'],
            };
            
            // 提取数值+单位的函数
            const extractValueWithUnit = (text) => {
              const results = [];
              // 匹配数值+单位的模式
              const patterns = [
                /(\d+\.?\d*)\s*°([CF])/gi,                    // 温度
                /(\d+\.?\d*)\s*%/g,                            // 百分比
                /(\d+\.?\d*)\s*(km²|m²|km\/h|mph|m\/s)/gi,     // 复合单位
                /(\d+\.?\d*)\s*(km|cm|mm|mi|ft|in|kg|mg|lb|oz|mL|gal|yr|mo|wk)\b/gi,  // 常用单位
                /(\d+\.?\d*)\s*(meters?|miles?|pounds?|gallons?|liters?|years?|months?|weeks?|days?|hours?|minutes?|seconds?)\b/gi,
                /(\d+\.?\d*)\s*(billion|million|thousand)\b/gi,  // 数量级
                /(\d+\.?\d*)\s*(人|公里|千米|米|公斤|升|年|月|周|天|小时)\b/g,  // 中文单位
              ];
              
              for (const pattern of patterns) {
                let match;
                const p = new RegExp(pattern.source, pattern.flags);
                while ((match = p.exec(text)) !== null) {
                  results.push({
                    full: match[0],
                    value: match[1],
                    unit: match[2] || ''
                  });
                }
              }
              return results;
            };
            
            // 标准化单位
            const normalizeUnit = (unit) => {
              const lowerUnit = unit.toLowerCase();
              for (const [standard, variants] of Object.entries(unitMappings)) {
                if (lowerUnit === standard.toLowerCase()) return standard;
                for (const variant of variants) {
                  if (lowerUnit === variant.toLowerCase() || lowerUnit.includes(variant.toLowerCase())) {
                    return standard;
                  }
                }
              }
              return unit;
            };
            
            // 提取解释文本中的数值+单位
            const expValueUnits = extractValueWithUnit(normalizedExplanation);
            console.log('[WeLearn-Go] fillEtChoice: 解释文本中的数值+单位:', expValueUnits.map(v => v.full));
            
            // ═══════════════════════════════════════════════════════════════
            // ★★★ 选项匹配评分系统 ★★★
            // ═══════════════════════════════════════════════════════════════
            let bestMatch = null;
            let bestScore = 0;
            
            options.forEach((opt, i) => {
              const optRaw = opt.textContent?.trim() || '';
              const optText = normalizeText(optRaw);
              let score = 0;
              let matchDetails = [];
              
              // 提取选项中的数值+单位
              const optValueUnits = extractValueWithUnit(optText);
              
              // ─────────────────────────────────────────────────────────────
              // 评分规则0: 数值+单位精确匹配 (最高优先级)
              // ─────────────────────────────────────────────────────────────
              for (const optVU of optValueUnits) {
                const optUnit = normalizeUnit(optVU.unit);
                const optValue = optVU.value;
                
                for (const expVU of expValueUnits) {
                  const expUnit = normalizeUnit(expVU.unit);
                  const expValue = expVU.value;
                  
                  // 数值相同
                  if (optValue === expValue) {
                    // 单位也相同 -> 完全匹配
                    if (optUnit === expUnit) {
                      score += 20;
                      matchDetails.push(`完全匹配: ${optValue}${optUnit}`);
                    } 
                    // 数值相同但单位不同 -> 可能是错误选项,减分
                    else if (optUnit && expUnit && optUnit !== expUnit) {
                      score -= 10;
                      matchDetails.push(`单位不匹配: ${optValue}${optUnit} vs ${expValue}${expUnit}`);
                    }
                  }
                }
              }
              
              // ─────────────────────────────────────────────────────────────
              // 评分规则1: 温度精确匹配 (数值+单位完全一致)
              // ─────────────────────────────────────────────────────────────
              const tempMatch = optText.match(/([\d.]+)°([CF])/i);
              if (tempMatch) {
                const optNum = tempMatch[1];
                const optUnit = tempMatch[2].toUpperCase();
                const expTempPattern = new RegExp(optNum.replace('.', '\\.') + '°' + optUnit, 'i');
                
                if (expTempPattern.test(normalizedExplanation)) {
                  score += 15;
                  matchDetails.push(`温度完全匹配: ${optNum}°${optUnit}`);
                } else {
                  // 检查是否数值匹配但单位错误
                  const wrongUnitPattern = new RegExp(optNum.replace('.', '\\.') + '°[CF]', 'i');
                  if (wrongUnitPattern.test(normalizedExplanation) && !expTempPattern.test(normalizedExplanation)) {
                    score -= 15;  // 数值对但单位错,强烈惩罚
                    matchDetails.push(`温度单位错误: 期望°${optUnit === 'C' ? 'F' : 'C'}`);
                  }
                }
              }
              
              // ─────────────────────────────────────────────────────────────
              // 评分规则2: 百分比精确匹配
              // ─────────────────────────────────────────────────────────────
              const percentMatch = optText.match(/([\d.]+)\s*%/);
              if (percentMatch) {
                const optPercent = percentMatch[1];
                if (normalizedExplanation.includes(optPercent + '%')) {
                  score += 15;
                  matchDetails.push(`百分比完全匹配: ${optPercent}%`);
                } else if (normalizedExplanation.includes(optPercent)) {
                  // 数值存在但不是百分比形式
                  score += 3;
                  matchDetails.push(`百分比数值存在: ${optPercent}`);
                }
              }
              
              // ─────────────────────────────────────────────────────────────
              // 评分规则3: 分数与百分比等价匹配
              // ─────────────────────────────────────────────────────────────
              for (const [fraction, percent] of Object.entries(fractionToPercent)) {
                if (optText.includes(fraction)) {
                  const percentStr = String(percent);
                  if (normalizedExplanation.includes(percentStr + '%') || 
                      normalizedExplanation.includes(percentStr)) {
                    score += 12;
                    matchDetails.push(`分数等价: ${fraction} = ${percent}%`);
                  }
                }
                const percentStr = String(percent);
                if (optText.includes(percentStr + '%')) {
                  if (normalizedExplanation.includes(fraction)) {
                    score += 12;
                    matchDetails.push(`百分比等价: ${percent}% = ${fraction}`);
                  }
                }
              }
              
              // ─────────────────────────────────────────────────────────────
              // 评分规则4: 比较词匹配 (>, <, ≈ 等)
              // ─────────────────────────────────────────────────────────────
              const comparators = ['>', '<', '≈', '≥', '≤'];
              for (const comp of comparators) {
                if (optText.includes(comp) && normalizedExplanation.includes(comp)) {
                  // 检查比较符后的数值是否匹配
                  const optCompMatch = optText.match(new RegExp(comp.replace(/[.*+?^${}()|[\]\\]/g, '\\$&') + '\\s*(\\d+\\.?\\d*)'));
                  const expCompMatch = normalizedExplanation.match(new RegExp(comp.replace(/[.*+?^${}()|[\]\\]/g, '\\$&') + '\\s*(\\d+\\.?\\d*)'));
                  if (optCompMatch && expCompMatch && optCompMatch[1] === expCompMatch[1]) {
                    score += 10;
                    matchDetails.push(`比较词匹配: ${comp}${optCompMatch[1]}`);
                  }
                }
              }
              
              // ─────────────────────────────────────────────────────────────
              // 评分规则5: 货币精确匹配
              // ─────────────────────────────────────────────────────────────
              const currencyMatch = optText.match(/([$€£¥])\s*([\d.]+)/);
              if (currencyMatch) {
                const symbol = currencyMatch[1];
                const amount = currencyMatch[2];
                if (normalizedExplanation.includes(symbol + amount) || 
                    normalizedExplanation.includes(symbol + ' ' + amount)) {
                  score += 12;
                  matchDetails.push(`货币匹配: ${symbol}${amount}`);
                }
              }
              
              // ─────────────────────────────────────────────────────────────
              // 评分规则6: 普通数值匹配 (需要更严格的上下文)
              // ─────────────────────────────────────────────────────────────
              const optNumbers = optText.match(/\b(\d+\.?\d*)\b/g) || [];
              for (const optNum of optNumbers) {
                // 检查是否是选项中的主要数值(排除序号等)
                if (optNum.length >= 2 || parseFloat(optNum) >= 10) {
                  // 精确匹配:数值两边是边界或非数字
                  const numPattern = new RegExp(`(^|[^\\d.])${optNum.replace('.', '\\.')}([^\\d.]|$)`);
                  if (numPattern.test(normalizedExplanation)) {
                    score += 8;
                    matchDetails.push(`数值匹配: ${optNum}`);
                  }
                }
              }
              
              // ─────────────────────────────────────────────────────────────
              // 评分规则7: 时间/年龄匹配
              // ─────────────────────────────────────────────────────────────
              const timeMatch = optText.match(/(\d+)\s*(世纪|年|月|周|天|小时|岁)/);
              if (timeMatch) {
                const timeNum = timeMatch[1];
                const timeUnit = timeMatch[2];
                if (normalizedExplanation.includes(timeNum + timeUnit) ||
                    normalizedExplanation.includes(timeNum + ' ' + timeUnit)) {
                  score += 10;
                  matchDetails.push(`时间匹配: ${timeNum}${timeUnit}`);
                }
              }
              
              console.log('[WeLearn-Go] fillEtChoice: 选项', i, '得分:', score, 
                matchDetails.length > 0 ? matchDetails.join('; ') : '无匹配',
                '| 原文:', optRaw.substring(0, 30));
              
              if (score > bestScore) {
                bestScore = score;
                bestMatch = opt;
                targetIdx = i;
              }
            });
            
            if (bestMatch && bestScore >= 5) {
              targetOption = bestMatch;
              console.log('[WeLearn-Go] fillEtChoice: 通过数值匹配找到答案,索引:', targetIdx, '得分:', bestScore);
              answerSource = '数值匹配';
              isReliable = false;  // 推断,可能有误
            }
          }
        }
        
        // ★★★ 方法6c: 关键词语义匹配(中英文通用)★★★
        // 用于非数值型选项,匹配解释文本中的关键词
        if (!targetOption) {
          console.log('[WeLearn-Go] fillEtChoice: 尝试关键词语义匹配');
          
          const expText = explanationText.toLowerCase();
          let bestMatch = null;
          let bestScore = 0;
          
          // 英文停用词
          const enStopWords = new Set(['it', 'is', 'a', 'an', 'the', 'to', 'by', 'in', 'of', 'for', 'has', 'been', 
            'was', 'will', 'be', 'about', 'that', 'this', 'with', 'are', 'have', 'do', 'does', 'and', 'or', 'but']);
          
          // 中文停用词
          const cnStopWords = new Set(['的', '了', '是', '在', '和', '与', '或', '及', '也', '都', '而', '但', 
            '这', '那', '个', '些', '所', '以', '为', '于', '从', '到', '等', '被', '把', '让', '使']);
          
          options.forEach((opt, i) => {
            const optText = (opt.textContent || '').trim();
            const optLower = optText.toLowerCase();
            let score = 0;
            let matchedWords = [];
            
            // ─────────────────────────────────────────────────────────────
            // 英文关键词提取和匹配
            // ─────────────────────────────────────────────────────────────
            const enWords = optLower.match(/[a-z]+/g) || [];
            for (const word of enWords) {
              if (word.length <= 2 || enStopWords.has(word)) continue;
              
              // 精确匹配
              if (expText.includes(word)) {
                score += 3;
                matchedWords.push(word);
              }
              // 词根匹配
              const stem = word.replace(/(ing|ed|s|ly|er|est|tion|ment|ness|able|ible)$/, '');
              if (stem.length > 3 && stem !== word && expText.includes(stem)) {
                score += 2;
                matchedWords.push(stem + '*');
              }
            }
            
            // ─────────────────────────────────────────────────────────────
            // 中文关键词提取和匹配
            // ─────────────────────────────────────────────────────────────
            const cnChars = optText.match(/[\u4e00-\u9fa5]+/g) || [];
            for (const phrase of cnChars) {
              // 跳过单字停用词
              if (phrase.length === 1 && cnStopWords.has(phrase)) continue;
              
              // 完整词组匹配
              if (expText.includes(phrase)) {
                score += phrase.length * 2;  // 中文匹配按字数加分
                matchedWords.push(phrase);
              }
              
              // 拆分成2字词组匹配
              if (phrase.length >= 2) {
                for (let j = 0; j < phrase.length - 1; j++) {
                  const biGram = phrase.substring(j, j + 2);
                  if (!cnStopWords.has(biGram[0]) && !cnStopWords.has(biGram[1])) {
                    if (expText.includes(biGram)) {
                      score += 1;
                    }
                  }
                }
              }
            }
            
            // ─────────────────────────────────────────────────────────────
            // 特殊语义匹配规则
            // ─────────────────────────────────────────────────────────────
            // 年份/世纪匹配
            const yearMatch = expText.match(/\b(17|18|19|20)\d{2}\b/);
            if (yearMatch && (optLower.includes('century') || optLower.includes('year') || optText.includes('世纪') || optText.includes('年'))) {
              const year = parseInt(yearMatch[0]);
              const age = new Date().getFullYear() - year;
              if ((optLower.includes('three') && optLower.includes('century')) || optText.includes('三') && optText.includes('世纪')) {
                if (age >= 250 && age <= 350) score += 8;
              }
            }
            
            // 增长/下降相关词
            const growthWords = ['increase', 'grow', 'rise', 'boom', 'surge', 'expand', '增长', '上升', '增加', '扩大'];
            const declineWords = ['decrease', 'fall', 'drop', 'decline', 'reduce', 'shrink', '下降', '减少', '降低', '缩小'];
            
            if (growthWords.some(w => optLower.includes(w) || optText.includes(w))) {
              if (growthWords.some(w => expText.includes(w))) score += 4;
              if (declineWords.some(w => expText.includes(w))) score -= 3;  // 相反语义减分
            }
            if (declineWords.some(w => optLower.includes(w) || optText.includes(w))) {
              if (declineWords.some(w => expText.includes(w))) score += 4;
              if (growthWords.some(w => expText.includes(w))) score -= 3;
            }
            
            // 最大/最小相关词
            const superlativeWords = ['biggest', 'largest', 'most', 'highest', 'best', 'greatest', '最大', '最多', '最高', '最好'];
            if (superlativeWords.some(w => optLower.includes(w) || optText.includes(w))) {
              if (superlativeWords.some(w => expText.includes(w))) score += 5;
            }
            
            console.log('[WeLearn-Go] fillEtChoice: 选项', i, '关键词得分:', score, 
              '匹配词:', matchedWords.slice(0, 5).join(','), 
              '| 选项:', optText.substring(0, 40));
            
            if (score > bestScore) {
              bestScore = score;
              bestMatch = opt;
              targetIdx = i;
            }
          });
          
          // 只有当得分足够高时才选择
          if (bestMatch && bestScore >= 5) {
            targetOption = bestMatch;
            console.log('[WeLearn-Go] fillEtChoice: 通过关键词语义匹配找到答案,索引:', targetIdx, '得分:', bestScore);
            answerSource = '关键词语义匹配';
            isReliable = false;  // 推断,可能有误
          }
        }
      }
    }
    
    // 如果没有找到答案,尝试最后的方法
    if (!targetOption) {
      // 方法7: 深度搜索 AngularJS scope 中的答案
      try {
        const scopeDoc = container.ownerDocument?.defaultView || window;
        const angular = scopeDoc.angular;
        
        if (angular) {
          const wrapper = container.querySelector('.wrapper');
          const scopeEl = wrapper || container;
          const scope = angular.element(scopeEl)?.scope();
          
          if (scope) {
            // 打印 scope 中所有包含 key/answer/correct 的属性
            const findAnswer = (obj, path = '', depth = 0) => {
              if (depth > 3 || !obj || typeof obj !== 'object') return null;
              
              for (const key of Object.keys(obj)) {
                if (key.startsWith('$') || key.startsWith('_')) continue;
                
                const val = obj[key];
                const fullPath = path ? `${path}.${key}` : key;
                
                // 直接检查 key/answer 属性
                if ((key === 'key' || key === 'answer' || key === 'correctIndex' || key === 'std_answer') && 
                    (typeof val === 'number' || typeof val === 'string')) {
                  console.log(`[WeLearn-Go] fillEtChoice: 发现 ${fullPath} = ${val}`);
                  
                  let idx = -1;
                  if (typeof val === 'number') {
                    idx = val >= 1 && val <= options.length ? val - 1 : val;
                  } else if (typeof val === 'string' && /^[A-Da-d]$/.test(val)) {
                    idx = val.toUpperCase().charCodeAt(0) - 65;
                  } else if (typeof val === 'string' && /^\d+$/.test(val)) {
                    idx = parseInt(val, 10) - 1;
                  }
                  
                  if (idx >= 0 && idx < options.length) {
                    targetOption = options[idx];
                    targetIdx = idx;
                    console.log('[WeLearn-Go] fillEtChoice: 通过深度搜索找到答案,索引:', idx);
                    return true;
                  }
                }
                
                // 递归搜索
                if (typeof val === 'object' && val !== null && !Array.isArray(val)) {
                  if (findAnswer(val, fullPath, depth + 1)) return true;
                }
              }
              return false;
            };
            
            findAnswer(scope);
          }
        }
      } catch (e) {
        console.debug('[WeLearn-Go] fillEtChoice: 深度搜索失败', e);
      }
    }
    
    // 方法8: ★★★ 使用 findAnswerFromExplanation 进行模糊匹配 ★★★
    if (!targetOption) {
      console.log('[WeLearn-Go] fillEtChoice: 尝试解释文本模糊匹配');
      const fuzzyMatch = findAnswerFromExplanation(container, options);
      if (fuzzyMatch) {
        targetOption = fuzzyMatch;
        targetIdx = options.indexOf(fuzzyMatch);
        console.log('[WeLearn-Go] fillEtChoice: 通过模糊匹配找到答案,索引:', targetIdx);
      }
    }
    
    // 如果还是没有找到答案,打印详细调试信息
    if (!targetOption) {
      console.warn('[WeLearn-Go] fillEtChoice: 无法确定正确答案,跳过填写');
      // 打印调试信息
      console.debug('[WeLearn-Go] fillEtChoice: container attrs:', 
        Array.from(container.attributes).map(a => `${a.name}="${a.value}"`).join(' '));
      
      // ★★★ 详细调试:输出完整的 scope 内容供分析 ★★★
      try {
        const scopeDoc = container.ownerDocument?.defaultView || window;
        const angular = scopeDoc.angular;
        if (angular) {
          const wrapper = container.querySelector('.wrapper');
          const scope = angular.element(wrapper || container)?.scope();
          if (scope?.choice) {
            console.log('[WeLearn-Go] fillEtChoice: ★★★ 请检查以下 choice 对象的内容 ★★★');
            console.log('[WeLearn-Go] choice =', scope.choice);
            console.log('[WeLearn-Go] choice.data =', scope.choice?.data);
            
            // 尝试遍历 choice 的所有属性
            const props = {};
            for (const k in scope.choice) {
              if (!k.startsWith('$') && !k.startsWith('_') && typeof scope.choice[k] !== 'function') {
                props[k] = scope.choice[k];
              }
            }
            console.log('[WeLearn-Go] choice 属性 (非函数):', props);
            
            // 打印 data 的详细内容
            if (scope.choice.data) {
              const dataProps = {};
              for (const k in scope.choice.data) {
                if (!k.startsWith('$') && typeof scope.choice.data[k] !== 'function') {
                  dataProps[k] = scope.choice.data[k];
                }
              }
              console.log('[WeLearn-Go] choice.data 属性:', dataProps);
            }
          } else {
            console.log('[WeLearn-Go] fillEtChoice: 未找到 scope.choice,scope 内容:', 
              Object.keys(scope || {}).filter(k => !k.startsWith('$')));
          }
        }
      } catch (e) {
        console.debug('[WeLearn-Go] fillEtChoice: 调试输出失败', e);
      }
      
      return false;
    }
    
    // ====== 3. 点击选项 ======
    // 检查是否已选中
    const isAlreadyChosen = targetOption.classList.contains('chosen') || 
                            targetOption.classList.contains('active') || 
                            targetOption.classList.contains('selected');
    if (isAlreadyChosen) {
      console.log('[WeLearn-Go] fillEtChoice: 选项已被选中,跳过');
      return false;
    }
    
    console.info('[WeLearn-Go] fillEtChoice: 点击选项', targetIdx, ':', targetOption.textContent?.trim()?.substring(0, 50));
    
    // ★★★ 如果答案来自解析推断,在控制台和页面上提示用户 ★★★
    if (!isReliable) {
      console.warn(`[WeLearn-Go] ⚠️ 答案来源: ${answerSource},存在一定错误率,请注意核对!`);
      
      // 在选项旁边添加警告标记
      try {
        const warningSpan = document.createElement('span');
        warningSpan.className = 'welearn-go-warning';
        warningSpan.style.cssText = 'color: #e67e22; font-size: 12px; margin-left: 5px; font-weight: bold;';
        warningSpan.textContent = '⚠️ 推断';
        warningSpan.title = `答案来源: ${answerSource}\n该答案通过解析文本推断,可能存在错误,请核对!`;
        
        // 检查是否已添加过警告
        if (!targetOption.querySelector('.welearn-go-warning')) {
          targetOption.appendChild(warningSpan);
        }
      } catch (e) {
        // 忽略添加标记失败
      }
    } else {
      console.info(`[WeLearn-Go] ✓ 答案来源: ${answerSource},标准答案`);
    }
    
    targetOption.click();
    
    // 触发 AngularJS 更新
    try {
      const scopeDoc = container.ownerDocument?.defaultView || window;
      const scope = scopeDoc.angular?.element(targetOption)?.scope();
      if (scope?.$apply) {
        scope.$apply();
      }
    } catch (e) { /* 忽略 */ }
    
    return true;
  };

  /**
   * 填充 et-tof 判断题(True/False 或自定义标签如 B/S)
   * 结构:<et-tof labels="B,S" key="t">
   *   <span ng-click="tof.chose('t')">B</span>  - 第一个选项(true)
   *   <span ng-click="tof.chose('f')">S</span>  - 第二个选项(false)
   * </et-tof>
   * 
   * 答案来源(按优先级):
   * 1. 元素的 key 属性(WELearnHelper 方式)- "t" 或 "f"
   * 2. 已显示的 .key 类
   * 3. AngularJS scope 的 isKey 方法
   * 
   * @param {Element} container - et-tof 容器元素
   * @returns {boolean} 是否成功填充
   */
  const fillEtTof = (container) => {
    console.info('[WeLearn-Go] fillEtTof: 开始处理', container.id, container.outerHTML?.substring(0, 200));
    
    // 获取正确的 window 对象(支持 iframe)
    const ownerWindow = container.ownerDocument?.defaultView || window;
    const angular = ownerWindow.angular;
    
    // 尝试多种方式查找选项容器
    let wrapper = container.querySelector('.wrapper');
    let controls = wrapper?.querySelector('.controls');
    
    // 如果标准结构找不到,直接在 container 中查找
    if (!controls) {
      controls = container.querySelector('.controls');
    }
    if (!controls) {
      controls = container.querySelector('span.controls');
    }
    
    console.info('[WeLearn-Go] fillEtTof: wrapper=', !!wrapper, 'controls=', !!controls);

    // 查找选项(多种选择器)- WELearnHelper 使用 'et-tof span.controls span'
    let options = [];
    if (controls) {
      options = Array.from(controls.querySelectorAll('span[ng-click*="chose"]'));
      // 备用:直接获取 controls 下的 span
      if (options.length < 2) {
        options = Array.from(controls.querySelectorAll('span'));
      }
    }
    // 备用:直接在 container 或 wrapper 中查找
    if (options.length < 2) {
      const searchIn = wrapper || container;
      options = Array.from(searchIn.querySelectorAll('span[ng-click*="chose"]'));
    }
    // 再备用:查找任何带有 ng-click 包含 tof 的 span
    if (options.length < 2) {
      options = Array.from(container.querySelectorAll('span[ng-click*="tof"]'));
    }
    
    console.info('[WeLearn-Go] fillEtTof: 找到选项数量:', options.length, options.map(o => o.textContent?.trim()));
    
    if (options.length < 2) {
      console.warn('[WeLearn-Go] fillEtTof: 选项不足', container.id);
      return false;
    }

    let keyOption = null;

    // ★★★ 方法0: 从 key 属性获取答案(WELearnHelper 的核心方式)★★★
    const keyAttr = container.getAttribute('key');
    if (keyAttr) {
      const keyVal = keyAttr.trim().toLowerCase();
      console.debug('[WeLearn-Go] fillEtTof: 发现 key 属性:', keyVal);
      
      // WELearnHelper 的逻辑:t/T = 第一个选项(索引0),f/F = 第二个选项(索引1)
      if (keyVal === 't') {
        keyOption = options[0];
        console.info('[WeLearn-Go] fillEtTof: 通过 key="t" 选择第一个选项');
      } else if (keyVal === 'f') {
        keyOption = options[1];
        console.info('[WeLearn-Go] fillEtTof: 通过 key="f" 选择第二个选项');
      }
    }

    // 方法1: 查找已有 .key 类的选项(答案已显示时)
    if (!keyOption) {
      keyOption = options.find(opt => opt.classList.contains('key'));
      if (keyOption) {
        console.info('[WeLearn-Go] fillEtTof: 通过 .key 类找到答案');
      }
    }

    // 方法2: 通过 AngularJS scope 获取正确答案
    if (!keyOption && angular) {
      try {
        const scope = angular.element(container)?.scope() || 
                      angular.element(wrapper || container)?.scope();
        
        if (scope?.tof) {
          console.info('[WeLearn-Go] fillEtTof: 找到 tof scope', Object.keys(scope.tof));
          
          // 尝试调用 isKey 方法
          if (typeof scope.tof.isKey === 'function') {
            if (scope.tof.isKey('t')) {
              keyOption = options.find(opt => {
                const ngClick = opt.getAttribute('ng-click') || '';
                return ngClick.includes("'t'") || ngClick.includes('"t"');
              });
              console.info('[WeLearn-Go] fillEtTof: isKey(t) = true');
            } else if (scope.tof.isKey('f')) {
              keyOption = options.find(opt => {
                const ngClick = opt.getAttribute('ng-click') || '';
                return ngClick.includes("'f'") || ngClick.includes('"f"');
              });
              console.info('[WeLearn-Go] fillEtTof: isKey(f) = true');
            }
          }
          
          // 尝试读取 key 属性
          if (!keyOption && scope.tof.key !== undefined) {
            const key = scope.tof.key;
            console.info('[WeLearn-Go] fillEtTof: tof.key =', key);
            keyOption = options.find(opt => {
              const ngClick = opt.getAttribute('ng-click') || '';
              return ngClick.includes(`'${key}'`) || ngClick.includes(`"${key}"`);
            });
          }
          
          // 尝试读取 data.key 属性
          if (!keyOption && scope.tof.data?.key !== undefined) {
            const key = scope.tof.data.key;
            console.info('[WeLearn-Go] fillEtTof: tof.data.key =', key);
            keyOption = options.find(opt => {
              const ngClick = opt.getAttribute('ng-click') || '';
              return ngClick.includes(`'${key}'`) || ngClick.includes(`"${key}"`);
            });
          }
        }
      } catch (e) {
        console.warn('[WeLearn-Go] fillEtTof: AngularJS scope 访问失败', e);
      }
    }

    // 方法3: 从 ng-class 中解析 key 状态
    if (!keyOption && angular) {
      for (const opt of options) {
        const ngClass = opt.getAttribute('ng-class') || '';
        // 格式类似: {chosen:tof.value[0] === 't', key: tof.isKey('t')}
        const keyMatch = ngClass.match(/key:\s*tof\.isKey\(['"](t|f)['"]\)/);
        if (keyMatch) {
          const keyValue = keyMatch[1];
          try {
            const scope = angular.element(opt)?.scope();
            if (scope?.tof?.isKey && scope.tof.isKey(keyValue)) {
              keyOption = opt;
              console.info(`[WeLearn-Go] fillEtTof: 从 ng-class 确认 isKey('${keyValue}') = true`);
              break;
            }
          } catch (e) { /* 忽略 */ }
        }
      }
    }

    if (!keyOption) {
      console.warn('[WeLearn-Go] fillEtTof: 无法确定正确答案', container.id);
      return false;
    }

    // 检查是否已选中
    if (keyOption.classList.contains('chosen')) {
      console.info('[WeLearn-Go] fillEtTof: 已经选中正确答案,跳过');
      return false; // 已经选中正确答案
    }

    // 点击正确选项
    console.info('[WeLearn-Go] fillEtTof: 选择答案', keyOption.textContent?.trim());
    keyOption.click();

    // 尝试触发 AngularJS 更新
    try {
      const scope = angular?.element(keyOption)?.scope();
      if (scope && scope.$apply) {
        scope.$apply();
      }
    } catch (e) { /* 忽略 */ }

    return true;
  };

  /**
   * 填充通用输入元素(input 或 contenteditable)
   * 尝试从父元素或相邻元素中查找答案
   * @param {Element} input - 输入元素
   * @param {Function} mutateAnswer - 答案变异函数
   * @returns {boolean} 是否成功填充
   */
  const fillGenericInput = (input, mutateAnswer) => {
    // 尝试查找答案:从父元素的 .key 或 data-solution 属性
    let solution = '';
    
    // 方法1: 查找同级或父级的 .key 元素
    const parent = input.closest('et-blank, .blank, .filling, [data-controltype]');
    if (parent) {
      const keyEl = parent.querySelector('.key, [data-itemtype="result"]');
      if (keyEl) {
        solution = normalizeAnswer(keyEl.textContent);
      }
    }
    
    // 方法2: 从 input 的 data-solution 属性获取
    if (!solution && input.dataset?.solution) {
      solution = normalizeAnswer(input.dataset.solution);
    }
    
    // 方法3: 查找 placeholder 中可能的提示
    if (!solution && input.placeholder) {
      // 有些题目会在 placeholder 中给出答案格式提示
    }
    
    if (!solution) return false;

    const finalValue = mutateAnswer(solution);
    
    // 判断是 contenteditable 还是 input
    if (input.hasAttribute('contenteditable')) {
      const currentValue = normalizeAnswer(input.textContent);
      if (currentValue === finalValue) return false;
      
      input.textContent = finalValue;
      input.dispatchEvent(new Event('input', { bubbles: true }));
      input.dispatchEvent(new Event('blur', { bubbles: true }));
    } else {
      // input 元素
      const currentValue = normalizeAnswer(input.value);
      if (currentValue === finalValue) return false;
      
      input.value = finalValue;
      input.dispatchEvent(new Event('input', { bubbles: true }));
      input.dispatchEvent(new Event('change', { bubbles: true }));
    }
    
    return true;
  };

  /** 检测是否为 Group Work 类型(有标准答案) */
  const detectGroupWork = (contexts) =>
    contexts.some((doc) => {
      const candidates = doc.querySelectorAll(
        '.subtitle2, .direction, .part_title, [data-controltype="group"], [data-controltype="page"], et-direction',
      );
      return Array.from(candidates).some((node) => GROUP_WORK_PATTERN.test(node.textContent || ''));
    });

  /** 检测是否为开放性题目(没有标准答案,如 "Answers may vary") */
  const detectOpenEndedGroupWork = (contexts) =>
    contexts.some((doc) => {
      // 检测 "Answers may vary" 开放性题目 - 需要更精确的匹配
      const allText = doc.body?.textContent || '';
      // 必须是完整的短语 "Answers may vary" 或 "Answer may vary"
      if (/\banswers?\s+(may|will|could|can)\s+vary\b/i.test(allText)) return true;
      
      // 检测带有 vary 类名的元素(用于标记开放性答案的特定类名)
      const varyElements = doc.querySelectorAll('.vary-answers, .answers-vary, [data-vary="true"]');
      return varyElements.length > 0;
    });

  /** 禁用自动提交功能 */
  const disableAutoSubmit = () => {
    const submitToggle = document.querySelector('.welearn-submit-toggle');
    if (submitToggle && submitToggle.checked) {
      submitToggle.checked = false;
      submitToggle.classList.remove('active');
    }
  };

  /** 处理有标准答案的 Group Work 模式(正常填充但禁用自动提交) */
  const handleGroupWorkMode = () => {
    groupWorkDetected = true;
    disableAutoSubmit();
    if (groupWorkNoticeShown) return;
    groupWorkNoticeShown = true;
    showToast('检测到 Group Work 讨论作业,已填充参考答案,请修改后再提交', {
      duration: 5000,
    });
  };

  /** 检查 fillinglong 是否有实质性答案(排除 "Answers may vary" 等占位文本) */
  const hasSubstantiveAnswer = (container) => {
    // 获取答案文本
    const resultEl = container.querySelector('[data-itemtype="result"]');
    const solutionAttr = container.querySelector('[data-solution]')?.getAttribute('data-solution');
    
    let answerText = resultEl?.textContent?.trim() || solutionAttr || '';
    
    // 清理答案文本
    answerText = cleanGroupWorkAnswer(answerText);
    
    // 如果清理后还有内容,则有实质性答案
    return answerText.length > 0;
  };

  /** 处理没有标准答案的开放性 Group Work(复制提示词到剪贴板) */
  const handleOpenEndedGroupWork = (contexts) => {
    groupWorkDetected = true;
    disableAutoSubmit();
    if (groupWorkNoticeShown) return;
    
    // 固定的提示词
    let promptText = '请根据要求完成题目,使用英语回答\n\n';
    
    // 记录是否有需要复制的主观题
    let hasSubjectiveQuestions = false;
    
    // 获取原始题目内容
    contexts.forEach((doc) => {
      // 优先获取 et-item 题目区域
      const etItems = doc.querySelectorAll('et-item');
      if (etItems.length > 0) {
        etItems.forEach((item) => {
          // 克隆节点以便移除不需要的元素
          const clone = item.cloneNode(true);
          // 移除底部的提示和按钮区域,以及 style 标签
          clone.querySelectorAll('style, script, .vary-answers, .key, .submit-btn, .btn, button, [class*="submit"], [class*="key"]').forEach(el => el.remove());
          
          let text = clone.innerText?.trim();
          if (text) {
            // 移除末尾的 "Answers may vary"、"Key"、提交时间、"Submit" 等
            text = text.replace(/\n*Answers?\s*(may|will)?\s*vary\.?\s*$/i, '');
            text = text.replace(/\n*Key\s*$/i, '');
            text = text.replace(/\n*上次在.*提交\s*$/i, '');
            text = text.replace(/\n*Submit\s*$/i, '');
            text = text.trim();
            if (text) {
              promptText += text + '\n\n';
              hasSubjectiveQuestions = true;
            }
          }
        });
        return;
      }
      
      // 其次尝试获取主观题(fillinglong)的题目区域,排除客观题(filling)
      const subjectiveAreas = doc.querySelectorAll('[data-controltype="fillinglong"]');
      if (subjectiveAreas.length > 0) {
        subjectiveAreas.forEach((area) => {
          // 检查是否有实质性答案,如果有则跳过(会被自动填充)
          if (hasSubstantiveAnswer(area)) return;
          
          // 克隆并清理
          const clone = area.cloneNode(true);
          clone.querySelectorAll('style, script, .key, [data-itemtype="result"], textarea').forEach(el => el.remove());
          
          let text = clone.innerText?.trim();
          if (text) {
            // 清理 "Answers may vary" 等文本
            text = text.replace(/\(?Answers?\s*(may|will|could|can)?\s*vary\.?\)?/gi, '');
            text = text.replace(/\n{3,}/g, '\n\n').trim();
            if (text) {
              promptText += text + '\n\n';
              hasSubjectiveQuestions = true;
            }
          }
        });
        // 已处理 fillinglong,继续下一个 doc
        return;
      }
      
      // 如果没有找到特定题目区域,尝试获取通用内容(但排除 filling 类型)
      const contentAreas = doc.querySelectorAll('.question-content, .exercise-content');
      if (contentAreas.length > 0) {
        contentAreas.forEach((area) => {
          const text = area.innerText?.trim();
          if (text) {
            promptText += text + '\n\n';
            hasSubjectiveQuestions = true;
          }
        });
        return;
      }
      
      // 最后尝试获取 body 内容(排除脚本等)- 只在特殊情况下使用
      // 对于混合题目页面,不使用此方法,避免复制客观题内容
    });
    
    // 只有在有需要 AI 生成的主观题时才复制到剪贴板
    if (!hasSubjectiveQuestions) {
      console.info('[WeLearn-Go] 没有需要 AI 生成的主观题,跳过剪贴板复制');
      return;
    }
    
    // 复制到剪贴板
    navigator.clipboard.writeText(promptText.trim()).then(() => {
      showToast('检测到无标准答案的主观题,提示词已复制,请使用 AI 生成后填写', {
        duration: 0,
      });
    }).catch((err) => {
      console.error('[WeLearn-Go] 复制到剪贴板失败:', err);
      showToast('检测到无标准答案的主观题,请手动复制题目使用 AI 生成', {
        duration: 0,
      });
    });
  };

  /** 处理开放式练习(如口语大纲、录音等,复制题目到剪贴板) */
  const handleOpenEndedExercise = (container) => {
    if (openEndedExerciseShown) return;
    openEndedExerciseShown = true;
    disableAutoSubmit();
    
    // 构建提示词
    let promptText = '请根据要求完成以下口语练习,使用英语回答\n\n';
    
    // 获取题目内容
    const clone = container.cloneNode(true);
    // 移除不需要的元素
    clone.querySelectorAll('style, script, .key, button, et-recorder, textarea').forEach(el => el.remove());
    
    let text = clone.innerText?.trim();
    if (text) {
      // 清理多余的空白行
      text = text.replace(/\n{3,}/g, '\n\n').trim();
      promptText += text + '\n\n';
    }
    
    // 添加提示
    promptText += '---\n请为上述大纲的每个部分提供简短的要点内容。';
    
    // 复制到剪贴板
    navigator.clipboard.writeText(promptText.trim()).then(() => {
      showToast('该练习没有标准答案(口语/开放式),题目已复制,请使用 AI 生成后填写', {
        duration: 0,
      });
    }).catch((err) => {
      console.error('[WeLearn-Go] 复制到剪贴板失败:', err);
      showToast('该练习没有标准答案,请手动复制题目使用 AI 生成', {
        duration: 0,
      });
    });
  };

  /**
   * 尝试填充 Vue 组件管理的题目
   * @param {Element} doc - 文档对象
   * @param {Function} mutate - 答案变异函数
   */
  const fillVueItems = (doc, mutate) => {
    let filled = false;
    // 查找所有可能的输入元素
    const inputs = Array.from(doc.querySelectorAll('input, textarea, .option, .choice, .item-option'));
    
    inputs.forEach(el => {
      // 尝试获取 Vue 实例
      let vue = el.__vue__;
      if (!vue && el.parentElement) vue = el.parentElement.__vue__;
      if (!vue && el.parentElement?.parentElement) vue = el.parentElement.parentElement.__vue__;
      
      if (!vue) return;
      
      // 尝试从 Vue 数据中查找答案
      const possibleKeys = ['answer', 'correctAnswer', 'solution', 'key', 'rightAnswer', 'correct'];
      let answer = null;
      
      for (const key of possibleKeys) {
        if (vue[key] !== undefined) answer = vue[key];
        else if (vue.$data?.[key] !== undefined) answer = vue.$data[key];
        else if (vue.props?.[key] !== undefined) answer = vue.props[key];
        
        if (answer) break;
      }
      
      if (!answer) {
        // 尝试从全局上下文获取
        answer = findAnswerFromGlobalContext(el);
      }
      
      if (!answer) return;
      
      // 规范化答案
      if (Array.isArray(answer)) answer = answer.join(',');
      if (typeof answer !== 'string') answer = String(answer);
      
      answer = normalizeAnswer(answer);
      if (!answer) return;
      
      const finalValue = mutate(answer);
      
      // 填充逻辑
      if (el.tagName === 'INPUT' || el.tagName === 'TEXTAREA') {
        if (el.value !== finalValue) {
          el.value = finalValue;
          el.dispatchEvent(new Event('input', { bubbles: true }));
          el.dispatchEvent(new Event('change', { bubbles: true }));
          filled = true;
        }
      } else {
        // 可能是选择题选项
        const text = normalizeAnswer(el.textContent);
        // 检查是否匹配答案 (例如 "A" 匹配 "A. Option Text")
        if (text === finalValue || (finalValue.length === 1 && text.startsWith(finalValue))) {
           const isActive = el.classList.contains('active') || el.classList.contains('selected') || el.classList.contains('checked');
           if (!isActive) {
             el.click();
             filled = true;
           }
        }
      }
    });
    
    return filled;
  };

  /**
   * 填充所有题目(主入口函数)
   * @param {Object} options - 配置选项
   * @param {boolean} options.enableSoftErrors - 是否启用小错误
   * @returns {Object} 包含 filled 和 errors 的结果对象
   */
  const fillAll = ({ enableSoftErrors = false } = {}) => {
    if (!isWeLearnPage()) {
      console.debug('[WeLearn-Go] fillAll: 不是 WeLearn 页面');
      return { filled: false, errors: [] };
    }
    const mutator = createMistakeMutator(enableSoftErrors);
    const contexts = getAccessibleDocuments();
    let filledAny = false;
    
    console.info('[WeLearn-Go] fillAll 开始执行,文档数量:', contexts.length);

    // 检测是否为 Group Work(有或没有标准答案)
    const isOpenEnded = detectOpenEndedGroupWork(contexts);
    groupWorkDetected = detectGroupWork(contexts) || isOpenEnded;
    
    if (groupWorkDetected) {
      // 禁用自动提交
      disableAutoSubmit();
    }

    contexts.forEach((doc) => {
      // 原有的填空题和选择题处理
      const fillings = Array.from(
        doc.querySelectorAll('[data-controltype="filling"], [data-controltype="fillinglong"]'),
      );
      const choices = Array.from(
        doc.querySelectorAll('[data-controltype="choice"], .checkbox_choice, .radio_choice, .normal_choice'),
      );
      
      // AngularJS 组件
      const etItems = Array.from(doc.querySelectorAll('et-item'));
      const standaloneToggles = Array.from(doc.querySelectorAll('et-toggle:not(et-item et-toggle)'));
      const standaloneBlanks = Array.from(doc.querySelectorAll('et-blank:not(et-item et-blank)'));
      const standaloneChoices = Array.from(doc.querySelectorAll('et-choice:not(et-item et-choice)'));
      const standaloneTofs = Array.from(doc.querySelectorAll('et-tof:not(et-item et-tof)'));
      
      console.info('[WeLearn-Go] 找到元素:', {
        fillings: fillings.length,
        choices: choices.length,
        etItems: etItems.length,
        standaloneToggles: standaloneToggles.length,
        standaloneBlanks: standaloneBlanks.length,
        etChoices: standaloneChoices.length,
        standaloneTofs: standaloneTofs.length,
        docLocation: doc === document ? 'main' : 'iframe'
      });

      fillings.forEach((container, idx) => {
        console.debug('[WeLearn-Go] 处理 filling #' + idx, container.getAttribute('data-id'), container.getAttribute('data-controltype'));
        const changed = fillFillingItem(container, mutator.mutate);
        filledAny = filledAny || changed;
      });

      choices.forEach((container) => {
        const changed = fillChoiceItem(container);
        filledAny = filledAny || changed;
      });

      // AngularJS 组件适配(et-item 系列)
      etItems.forEach((etItem) => {
        console.info('[WeLearn-Go] 处理 et-item:', etItem.id, 'isNoInteraction:', isNoInteractionItem(etItem));
        const changed = fillEtItem(etItem, mutator.mutate);
        console.info('[WeLearn-Go] fillEtItem 返回:', changed);
        filledAny = filledAny || changed;
      });

      // 页面级别的 et-toggle 处理(不在 et-item 内的)
      standaloneToggles.forEach((toggle) => {
        const changed = fillEtToggle(toggle, mutator.mutate);
        filledAny = filledAny || changed;
      });

      // 页面级别的 et-blank 处理(不在 et-item 内的)
      standaloneBlanks.forEach((blank) => {
        const changed = fillEtBlank(blank, mutator.mutate);
        filledAny = filledAny || changed;
      });

      // 页面级别的 et-choice 二选一选择题处理
      standaloneChoices.forEach((choice) => {
        const changed = fillEtChoice(choice);
        filledAny = filledAny || changed;
      });

      // 页面级别的 et-tof 判断题处理(不在 et-item 内的)
      standaloneTofs.forEach((tof) => {
        const changed = fillEtTof(tof);
        filledAny = filledAny || changed;
      });

      // Vue 组件处理
      const vueChanged = fillVueItems(doc, mutator.mutate);
      filledAny = filledAny || vueChanged;
    });

    // 如果检测到开放性题目(Answers may vary),复制没有标准答案的主观题到剪贴板
    if (isOpenEnded) {
      handleOpenEndedGroupWork(contexts);
    }
    
    // 显示 Group Work 提示
    if (groupWorkDetected && !groupWorkNoticeShown) {
      groupWorkNoticeShown = true;
      
      // 检查是否有 fillinglong(主观题)被填充
      const hasFilledSubjective = contexts.some(doc => {
        const fillinglongs = doc.querySelectorAll('[data-controltype="fillinglong"]');
        return Array.from(fillinglongs).some(el => {
          const textarea = el.querySelector('textarea');
          return textarea && textarea.value.trim().length > 0;
        });
      });
      
      if (hasFilledSubjective) {
        // 有主观题被填充了参考答案
        showToast('检测到 Group Work / Pair Work,已填充参考答案,建议修改或使用 AI 重写后再提交', {
          duration: 6000,
        });
      } else if (filledAny) {
        // 只填充了客观题
        showToast('检测到 Group Work / Pair Work,已填充客观题,请检查后提交', {
          duration: 5000,
        });
      }
    }

    return { filled: filledAny, errors: mutator.getErrors(), targetCount: mutator.getTargetCount() };
  };

  /** 自动提交答案(如果启用且不是 Group Work) */
  const submitIfNeeded = (shouldSubmit) => {
    if (!shouldSubmit || !isWeLearnPage() || groupWorkDetected) return;
    const contexts = getAccessibleDocuments();
    
    // 查找并点击提交按钮
    for (const doc of contexts) {
      // 方法1:原有的 data-controltype="submit" 选择器
      let submitButton = doc.querySelector('[data-controltype="submit"]');
      if (submitButton) {
        if (!submitButton.disabled && !submitButton.hasAttribute('disabled')) {
          submitButton.click();
          console.log('[WeLearn] 已点击提交按钮 (data-controltype)');
          return;
        }
      }
      
      // 方法2:查找 et-button[action*="submit"] 的 AngularJS 按钮
      // 这种按钮结构是: <et-button action="item.submit()"><button ng-click="btn.doAction()">
      const etButtons = doc.querySelectorAll('et-button[action*="submit"]');
      for (const etBtn of etButtons) {
        // 检查是否可见且未禁用
        const isHidden = etBtn.classList.contains('ng-hide') || 
                         etBtn.style.display === 'none' ||
                         etBtn.offsetParent === null;
        const isDisabled = etBtn.hasAttribute('disabled') && 
                           etBtn.getAttribute('disabled') !== 'false';
        
        if (!isHidden && !isDisabled) {
          const innerBtn = etBtn.querySelector('button');
          if (innerBtn && !innerBtn.disabled) {
            // 尝试通过 AngularJS scope 调用
            try {
              const scope = angular.element(etBtn).isolateScope() || 
                           angular.element(etBtn).scope();
              if (scope && scope.btn && typeof scope.btn.doAction === 'function') {
                scope.btn.doAction();
                console.log('[WeLearn] 已调用 btn.doAction() 提交');
                return;
              }
            } catch (e) {
              console.log('[WeLearn] AngularJS 调用失败,尝试直接点击');
            }
            
            // 回退:直接点击按钮
            innerBtn.click();
            console.log('[WeLearn] 已点击提交按钮 (et-button)');
            return;
          }
        }
      }
      
      // 方法3:查找 controls 区域中未提交状态的按钮
      // 特征:在 et-item .controls 内,ng-hide="item.isSubmitted"
      const controlsArea = doc.querySelector('et-item > .controls');
      if (controlsArea) {
        const buttons = controlsArea.querySelectorAll('et-button');
        for (const btn of buttons) {
          const ngHide = btn.getAttribute('ng-hide');
          // 查找带 isSubmitted 条件的按钮(未提交时显示)
          if (ngHide && ngHide.includes('isSubmitted')) {
            const innerBtn = btn.querySelector('button');
            if (innerBtn && !innerBtn.disabled && btn.offsetParent !== null) {
              try {
                const scope = angular.element(btn).isolateScope() || 
                             angular.element(btn).scope();
                if (scope && scope.btn && typeof scope.btn.doAction === 'function') {
                  scope.btn.doAction();
                  console.log('[WeLearn] 已调用控制区提交按钮');
                  return;
                }
              } catch (e) {
                // 忽略
              }
              innerBtn.click();
              console.log('[WeLearn] 已点击控制区提交按钮');
              return;
            }
          }
        }
      }
      
      // 方法4:通过 et-item 的 scope 直接调用 submit
      const etItems = doc.querySelectorAll('et-item');
      for (const etItem of etItems) {
        try {
          const scope = angular.element(etItem).scope();
          if (scope && scope.item && typeof scope.item.submit === 'function') {
            // 检查是否已提交
            if (!scope.item.isSubmitted && !scope.item.suspendSubmit) {
              scope.item.submit();
              console.log('[WeLearn] 已通过 scope.item.submit() 提交');
              return;
            }
          }
        } catch (e) {
          // 忽略
        }
      }
    }
    
    console.log('[WeLearn] 未找到可用的提交按钮');
  };

  /** 
   * 自动处理提交确认对话框
   * 当点击提交按钮后,可能会弹出 layui 对话框要求二次确认
   * 此函数会自动点击"是"按钮完成确认
   */
  const autoConfirmSubmitDialog = () => {
    // 使用 MutationObserver 监听对话框的出现
    const observer = new MutationObserver((mutations) => {
      for (const mutation of mutations) {
        for (const node of mutation.addedNodes) {
          if (node.nodeType !== Node.ELEMENT_NODE) continue;
          
          // 检查是否是 layui 对话框
          if (node.classList?.contains('layui-layer-dialog') || 
              node.querySelector?.('.layui-layer-dialog')) {
            
            const dialog = node.classList.contains('layui-layer-dialog') 
              ? node 
              : node.querySelector('.layui-layer-dialog');
            
            if (!dialog) continue;
            
            // 检查对话框内容是否包含提交确认文字
            const content = dialog.querySelector('.layui-layer-content');
            if (content && content.textContent?.includes('提交')) {
              // 查找"是"按钮并点击
              const confirmBtn = dialog.querySelector('.layui-layer-btn0');
              if (confirmBtn) {
                console.log('[WeLearn-Go] 自动确认提交对话框');
                setTimeout(() => {
                  confirmBtn.click();
                }, 100);
              }
            }
          }
        }
      }
    });
    
    observer.observe(document.body, {
      childList: true,
      subtree: true
    });
    
    // 返回一个清理函数
    return () => observer.disconnect();
  };

  // 启动自动确认监听
  let confirmDialogCleanup = null;
  const startAutoConfirmDialog = () => {
    if (!confirmDialogCleanup) {
      confirmDialogCleanup = autoConfirmSubmitDialog();
    }
  };

  // ==================== 批量任务处理功能 ====================

  /** 加载已完成的任务记录 */
  const loadBatchCompleted = () => {
    try {
      const raw = localStorage.getItem(BATCH_COMPLETED_KEY);
      return raw ? JSON.parse(raw) : {};
    } catch (error) {
      console.warn('WeLearn: 加载已完成记录失败', error);
      return {};
    }
  };

  /** 保存已完成的任务记录 */
  const saveBatchCompleted = (completed) => {
    try {
      localStorage.setItem(BATCH_COMPLETED_KEY, JSON.stringify(completed));
    } catch (error) {
      console.warn('WeLearn: 保存已完成记录失败', error);
    }
  };

  /** 标记任务为已完成 */
  const markTaskCompleted = (taskId, courseName) => {
    const completed = loadBatchCompleted();
    if (!completed[courseName]) {
      completed[courseName] = [];
    }
    if (!completed[courseName].includes(taskId)) {
      completed[courseName].push(taskId);
      saveBatchCompleted(completed);
    }
  };

  /** 检查任务是否已完成 */
  const isTaskCompleted = (taskId, courseName) => {
    const completed = loadBatchCompleted();
    return completed[courseName]?.includes(taskId) || false;
  };

  /** 清除课程的完成记录 */
  const clearCourseCompleted = (courseName) => {
    const completed = loadBatchCompleted();
    if (completed[courseName]) {
      delete completed[courseName];
      saveBatchCompleted(completed);
    }
  };

  /** 保存批量模式状态 */
  const saveBatchModeState = (state) => {
    try {
      // 添加时间戳用于检测异常关闭
      state.lastUpdate = Date.now();
      localStorage.setItem(BATCH_MODE_KEY, JSON.stringify(state));
    } catch (error) {
      console.warn('WeLearn: 保存批量模式状态失败', error);
    }
  };

  /** 加载批量模式状态 */
  const loadBatchModeState = () => {
    try {
      const raw = localStorage.getItem(BATCH_MODE_KEY);
      return raw ? JSON.parse(raw) : null;
    } catch (error) {
      console.warn('WeLearn: 加载批量模式状态失败', error);
      return null;
    }
  };

  /** 清除批量模式状态 */
  const clearBatchModeState = () => {
    try {
      localStorage.removeItem(BATCH_MODE_KEY);
    } catch (error) {
      console.warn('WeLearn: 清除批量模式状态失败', error);
    }
  };

  /** 获取当前课程 ID */
  const getCourseId = () => {
    const urlParams = new URLSearchParams(window.location.search);
    return urlParams.get('cid') || '';
  };

  /** 获取当前课程名称 */
  const getCourseName = () => {
    // 尝试从页面标题或特定元素获取课程名
    const courseTitle = document.querySelector('.course_title, .courseName, #courseName, .courseware_title');
    if (courseTitle) {
      return courseTitle.textContent?.trim() || '未知课程';
    }
    // 从 URL 参数获取课程 ID
    const cid = getCourseId();
    return cid ? `课程 ${cid}` : '未知课程';
  };

  /** 保存课程目录缓存 */
  const saveCourseDirectoryCache = (courseId, courseName, tasks) => {
    try {
      const cache = {
        courseId,
        courseName,
        tasks,
        timestamp: Date.now()
      };
      localStorage.setItem(COURSE_DIRECTORY_CACHE_KEY, JSON.stringify(cache));
      console.info('[WeLearn-Go] 课程目录已缓存:', courseName, tasks.length, '个任务');
    } catch (error) {
      console.warn('[WeLearn-Go] 保存目录缓存失败:', error);
    }
  };

  /** 加载课程目录缓存 */
  const loadCourseDirectoryCache = () => {
    try {
      const raw = localStorage.getItem(COURSE_DIRECTORY_CACHE_KEY);
      if (!raw) return null;
      return JSON.parse(raw);
    } catch (error) {
      console.warn('[WeLearn-Go] 加载目录缓存失败:', error);
      return null;
    }
  };

  /** 保存批量任务选择缓存 */
  const saveBatchTasksCache = (courseName, tasks) => {
    try {
      const cache = {
        courseName,
        tasks,
        timestamp: Date.now()
      };
      localStorage.setItem(BATCH_TASKS_CACHE_KEY, JSON.stringify(cache));
      console.info('[WeLearn-Go] 批量任务已缓存:', tasks.length, '个任务');
    } catch (error) {
      console.warn('[WeLearn-Go] 保存任务缓存失败:', error);
    }
  };

  /** 加载批量任务选择缓存 */
  const loadBatchTasksCache = () => {
    try {
      const raw = localStorage.getItem(BATCH_TASKS_CACHE_KEY);
      if (!raw) return null;
      return JSON.parse(raw);
    } catch (error) {
      console.warn('[WeLearn-Go] 加载任务缓存失败:', error);
      return null;
    }
  };

  /** 清除批量任务选择缓存 */
  const clearBatchTasksCache = () => {
    try {
      localStorage.removeItem(BATCH_TASKS_CACHE_KEY);
    } catch (error) {
      console.warn('[WeLearn-Go] 清除任务缓存失败:', error);
    }
  };

  /** 扫描页面上所有可执行的任务元素 
   * @param {Object} options - 配置选项
   * @param {boolean} options.ignoreLocalCompleted - 是否忽略本地完成记录,只看页面状态
   */
  const scanPageForTasks = ({ ignoreLocalCompleted = false } = {}) => {
    const tasks = [];
    const seenIds = new Set();
    const completed = loadBatchCompleted();
    const courseName = getCourseName();
    // 如果 ignoreLocalCompleted 为 true,则不使用本地记录
    const completedTasks = ignoreLocalCompleted ? [] : (completed[courseName] || []);

    console.log('[WeLearn-Go] 开始扫描页面任务...');
    
    // 通用方法: 查找所有包含 StartSCO 的 onclick 元素
    const allClickableElements = document.querySelectorAll('[onclick*="StartSCO"]');
    console.log('[WeLearn-Go] 找到 StartSCO 元素:', allClickableElements.length);
    
    allClickableElements.forEach((el) => {
      const onclickAttr = el.getAttribute('onclick') || '';
      const scoMatch = onclickAttr.match(/StartSCO\s*\(\s*['"]([^'"]+)['"]\s*\)/);
      if (!scoMatch) return;
      
      const taskId = scoMatch[1];
      if (seenIds.has(taskId)) return;
      seenIds.add(taskId);
      
      // 获取标题 - 尝试多种方式
      let title = '';
      
      // 尝试从 span 子元素获取
      const span = el.querySelector('span');
      if (span) {
        const spanClone = span.cloneNode(true);
        // 移除图标
        spanClone.querySelectorAll('i, .fa, .icon').forEach(icon => icon.remove());
        title = spanClone.textContent?.trim() || '';
      }
      
      // 尝试从 a 标签获取
      if (!title) {
        const link = el.querySelector('a');
        title = link?.getAttribute('title') || link?.textContent?.trim() || '';
      }
      
      // 尝试从元素本身获取文本
      if (!title) {
        const elClone = el.cloneNode(true);
        elClone.querySelectorAll('i, .fa, .icon, .progress, .badge').forEach(n => n.remove());
        title = elClone.textContent?.trim().substring(0, 80) || taskId;
      }
      
      // 获取父级单元名称
      let unitName = '';
      let isIntro = false; // 是否是课程介绍类(0/0任务组)
      
      // 尝试从最近的 panel-heading 获取
      const panelHeading = el.closest('.panel')?.querySelector('.panel-title > a');
      if (panelHeading) {
        const headingClone = panelHeading.cloneNode(true);
        headingClone.querySelectorAll('.progress_fix, .badge').forEach(n => n.remove());
        unitName = headingClone.textContent?.trim() || '';
        
        // 检查是否是 0/0 任务组(课程介绍类)
        const progressFix = el.closest('.panel')?.querySelector('.progress_fix');
        if (progressFix) {
          const progressText = progressFix.textContent || '';
          // 匹配类似 "X /0" 的模式,表示总任务数为0
          if (/\/\s*0\s*$/.test(progressText)) {
            isIntro = true;
          }
        }
      }
      
      // 尝试从 u_listtitle 获取
      if (!unitName) {
        let prevEl = el.previousElementSibling || el.parentElement;
        while (prevEl && !unitName) {
          if (prevEl.classList?.contains('u_listtitle')) {
            unitName = prevEl.textContent?.trim().substring(0, 50) || '';
            break;
          }
          prevEl = prevEl.previousElementSibling || prevEl.parentElement;
        }
      }
      
      // 判断状态
      const isDisabled = el.classList.contains('disabled') || 
                        el.classList.contains('list-disabled') ||
                        el.classList.contains('course_disable');
      
      // 检测页面上的完成状态 - 支持多种可能的完成标识
      const icon = el.querySelector('i.fa');
      let pageCompleted = false;
      
      // 方式1: 检查图标类名 (支持多种完成图标)
      if (icon) {
        pageCompleted = icon.classList.contains('fa-check-circle-o') ||
                       icon.classList.contains('fa-check-circle') ||
                       icon.classList.contains('fa-check') ||
                       icon.classList.contains('fa-check-square-o') ||
                       icon.classList.contains('fa-check-square');
      }
      
      // 方式2: 检查元素或父元素是否有完成相关的类名
      if (!pageCompleted) {
        pageCompleted = el.classList.contains('completed') ||
                       el.classList.contains('finish') ||
                       el.classList.contains('done') ||
                       el.classList.contains('success') ||
                       el.closest('.completed, .finish, .done') !== null;
      }
      
      // 方式3: 检查进度条是否满 (100%)
      if (!pageCompleted) {
        const progressBar = el.querySelector('.progress-bar, .progress');
        if (progressBar) {
          const widthStyle = progressBar.style.width;
          if (widthStyle === '100%') {
            pageCompleted = true;
          }
          // 检查 aria-valuenow 属性
          const ariaValue = progressBar.getAttribute('aria-valuenow');
          if (ariaValue === '100') {
            pageCompleted = true;
          }
        }
      }
      
      // 方式4: 检查文本内容是否包含完成标识
      if (!pageCompleted) {
        const statusBadge = el.querySelector('.badge, .status, .label');
        if (statusBadge) {
          const statusText = statusBadge.textContent?.trim() || '';
          if (/已完成|完成|Completed|Done|Finished|100%/i.test(statusText)) {
            pageCompleted = true;
          }
        }
      }
      
      // 方式5: 检查图标颜色 (绿色通常表示完成)
      if (!pageCompleted && icon) {
        const iconColor = getComputedStyle(icon).color;
        // 绿色色值检测 (包括各种绿色变体)
        if (iconColor && /rgb\(\s*\d{1,2}\s*,\s*(1\d{2}|2[0-4]\d|25[0-5])\s*,\s*\d{1,2}\s*\)/.test(iconColor)) {
          // 这是一个大致的绿色检测,G值较高且R、B值较低
          const match = iconColor.match(/rgb\(\s*(\d+)\s*,\s*(\d+)\s*,\s*(\d+)\s*\)/);
          if (match) {
            const [, r, g, b] = match.map(Number);
            if (g > 100 && g > r && g > b) {
              pageCompleted = true;
            }
          }
        }
      }
      
      const isCompletedByUs = completedTasks.includes(taskId);
      const isCompleted = isCompletedByUs || pageCompleted;
      
      // 调试日志:输出每个任务的完成状态检测结果
      if (pageCompleted) {
        console.log('[WeLearn-Go] 任务已完成(页面):', taskId, title.substring(0, 30));
      }
      
      tasks.push({
        id: taskId,
        title: title,
        unitName: unitName,
        isDisabled: isDisabled,
        isCompleted: isCompleted,
        isIntro: isIntro,
        element: el,
        onclick: onclickAttr
      });
    });

    // 如果没有找到 StartSCO,尝试其他结构
    if (tasks.length === 0) {
      console.log('[WeLearn-Go] 未找到 StartSCO 元素,尝试其他结构...');
      
      // 旧版结构: courseware_list
      const coursewareItems = document.querySelectorAll('.courseware_list_1_3, .courseware_list_1_4');
      console.log('[WeLearn-Go] 找到 courseware_list 元素:', coursewareItems.length);
      
      coursewareItems.forEach((item) => {
        const taskId = item.id || item.getAttribute('data-sco') || '';
        if (!taskId || seenIds.has(taskId)) return;
        seenIds.add(taskId);
        
        const link = item.querySelector('a');
        const title = link?.getAttribute('title') || link?.textContent?.trim() || '';
        
        const isDisabled = item.classList.contains('course_disable');
        const isCompletedByUs = completedTasks.includes(taskId);
        
        // 检测页面完成状态 - 多种方式
        let pageCompleted = false;
        
        // 方式1: 检查完成相关的元素
        const hasProgressComplete = item.querySelector('.progress-complete, .completed, .finish, .done');
        if (hasProgressComplete) {
          pageCompleted = true;
        }
        
        // 方式2: 检查图标
        if (!pageCompleted) {
          const icon = item.querySelector('i.fa');
          if (icon) {
            pageCompleted = icon.classList.contains('fa-check-circle-o') ||
                           icon.classList.contains('fa-check-circle') ||
                           icon.classList.contains('fa-check') ||
                           icon.classList.contains('fa-check-square-o') ||
                           icon.classList.contains('fa-check-square');
          }
        }
        
        // 方式3: 检查进度条
        if (!pageCompleted) {
          const progressBar = item.querySelector('.progress-bar, .progress');
          if (progressBar) {
            const widthStyle = progressBar.style.width;
            const ariaValue = progressBar.getAttribute('aria-valuenow');
            if (widthStyle === '100%' || ariaValue === '100') {
              pageCompleted = true;
            }
          }
        }
        
        // 方式4: 检查状态文本
        if (!pageCompleted) {
          const statusBadge = item.querySelector('.badge, .status, .label');
          if (statusBadge) {
            const statusText = statusBadge.textContent?.trim() || '';
            if (/已完成|完成|Completed|Done|Finished|100%/i.test(statusText)) {
              pageCompleted = true;
            }
          }
        }
        
        const isCompleted = isCompletedByUs || pageCompleted;

        let unitName = '';
        const categoryContainer = item.closest('.categoryitems');
        if (categoryContainer) {
          const prevHeader = categoryContainer.previousElementSibling;
          if (prevHeader?.classList?.contains('courseware_list_1_1')) {
            const unitSpan = prevHeader.querySelector('.v_1');
            unitName = unitSpan?.textContent?.trim() || '';
          }
        }

        if (title && taskId) {
          tasks.push({
            id: taskId,
            title: title,
            unitName: unitName,
            isDisabled: isDisabled,
            isCompleted: isCompleted,
            element: item
          });
        }
      });
    }

    // 统计完成状态
    const completedCount = tasks.filter(t => t.isCompleted).length;
    const pendingCount = tasks.filter(t => !t.isCompleted && !t.isDisabled && !t.isIntro).length;
    console.log('[WeLearn-Go] 扫描完成,共找到任务:', tasks.length, 
                '| 已完成:', completedCount, 
                '| 待完成:', pendingCount);
    return tasks;
  };

  /** 获取课程目录中的所有任务(使用扫描方法)
   * @param {Object} options - 配置选项
   * @param {boolean} options.ignoreLocalCompleted - 是否忽略本地完成记录
   */
  const getCourseTaskList = (options = {}) => {
    return scanPageForTasks(options);
  };

  /** 展开所有目录项 */
  const expandAllCategories = async () => {
    // 检测是否在 course_info.aspx 页面
    const isCourseInfoPage = window.location.href.includes('course_info.aspx');
    
    if (isCourseInfoPage) {
      // 首先确保点击了"目录"标签
      const tabs = document.querySelectorAll('.nav-tabs li a, .course-tabs a, [role="tab"]');
      for (const tab of tabs) {
        if (tab.textContent?.includes('目录')) {
          tab.click();
          await new Promise(resolve => setTimeout(resolve, 500));
          break;
        }
      }
      
      // 展开所有单元 (点击每个单元行的展开按钮)
      const unitRows = document.querySelectorAll('.u_listtitle, .unit-row, [data-toggle="collapse"]');
      for (const row of unitRows) {
        // 检查是否已展开
        const isExpanded = row.classList.contains('expanded') || 
                          row.getAttribute('aria-expanded') === 'true';
        if (!isExpanded) {
          const expandBtn = row.querySelector('.expand-btn, .plus-icon, .fa-plus') || row;
          expandBtn.click();
          await new Promise(resolve => setTimeout(resolve, 300));
        }
      }
    }
    
    // stu_unitlist 结构: 点击 collapsed 的 panel 标题来展开
    const collapsedPanels = document.querySelectorAll('.stu_unitlist .panel-title > a.collapsed');
    for (const link of collapsedPanels) {
      link.click();
      await new Promise(resolve => setTimeout(resolve, 200));
    }
    
    // 旧版结构: 点击所有折叠的单元头部来展开
    const collapsedHeaders = document.querySelectorAll('.courseware_list_1_1:not(.openheader)');
    collapsedHeaders.forEach((header) => {
      header.click();
    });
    
    // 等待展开动画完成
    return new Promise(resolve => setTimeout(resolve, 800));
  };

  /** 检查当前页面是否是课程目录页面(而非任务执行页面) */
  const isOnCourseDirectoryPage = () => {
    const url = window.location.href;
    // 任务执行页面包含 StudyCourse.aspx,不是目录页面
    if (url.includes('StudyCourse.aspx')) {
      return false;
    }
    // 目录页面的 URL 特征
    return url.includes('course_info.aspx') || 
           url.includes('study.aspx') ||
           url.includes('directory.aspx');
  };

  /** 生成任务列表 HTML */
  const generateTasksHtml = (availableTasks, savedTaskIds = []) => {
    // 按单元分组任务
    const tasksByUnit = {};
    availableTasks.forEach(task => {
      const unit = task.unitName || '其他';
      if (!tasksByUnit[unit]) {
        tasksByUnit[unit] = [];
      }
      tasksByUnit[unit].push(task);
    });

    let tasksHtml = '';
    Object.entries(tasksByUnit).forEach(([unitName, unitTasks]) => {
      // 检测是否是"课程说明"类型的单元(通过名称或 isIntro 属性)
      const isIntroUnit = unitTasks.every(t => t.isIntro) || 
                          /^课程(说明|介绍|简介)/.test(unitName) ||
                          /^(Course\s*)?(Introduction|Info|Description)/i.test(unitName);
      
      tasksHtml += `
        <div class="welearn-task-unit">
          <div class="welearn-task-unit-header">
            <label class="welearn-checkbox-label">
              <input type="checkbox" class="welearn-unit-checkbox" data-unit="${unitName}" ${isIntroUnit ? 'disabled' : ''}>
              <span>${unitName || '任务列表'}</span>
            </label>
          </div>
          <div class="welearn-task-list">
            ${unitTasks.map(task => {
              const taskIsIntro = task.isIntro || isIntroUnit;
              return `
              <label class="welearn-task-item ${task.isCompleted ? 'completed' : ''} ${taskIsIntro ? 'intro' : ''}">
                <input type="checkbox" class="welearn-task-checkbox" 
                       data-task-id="${task.id}" 
                       data-title="${task.title}"
                       ${task.isCompleted || taskIsIntro ? 'disabled' : ''}
                       ${savedTaskIds.includes(task.id) && !task.isCompleted && !taskIsIntro ? 'checked' : ''}>
                <span class="welearn-task-title">${task.title}</span>
                ${task.isCompleted 
                  ? '<span class="welearn-task-badge">✓ 已完成</span>' 
                  : taskIsIntro
                    ? '<span class="welearn-task-badge intro">◇ 无需填写</span>'
                    : '<span class="welearn-task-badge pending">○ 待完成</span>'}
              </label>
            `}).join('')}
          </div>
        </div>
      `;
    });
    return tasksHtml;
  };

  /** 显示任务选择模态框 */
  const showTaskSelectorModal = async (forceRefresh = false) => {
    const currentCourseId = getCourseId();
    const currentCourseName = getCourseName();
    const cache = loadCourseDirectoryCache();
    const tasksCache = loadBatchTasksCache();
    
    // 检查是否有可用缓存且课程匹配
    const hasCacheForCurrentCourse = cache && cache.courseId === currentCourseId && cache.tasks?.length > 0;
    const courseIdMismatch = cache && cache.courseId && cache.courseId !== currentCourseId;
    
    // 创建模态框
    const overlay = document.createElement('div');
    overlay.className = 'welearn-modal-overlay welearn-task-selector';
    
    // 显示加载动画
    const showLoading = () => {
      overlay.innerHTML = `
        <div class="welearn-modal welearn-task-modal">
          <h3>📖 课程目录 - ${currentCourseName}</h3>
          <div class="welearn-loading-container">
            <div class="welearn-loading-spinner"></div>
            <p>正在读取课程目录...</p>
          </div>
        </div>
      `;
    };
    
    // 渲染任务列表
    const renderTaskList = (availableTasks, showMismatchWarning = false, isFromCache = false) => {
      if (availableTasks.length === 0) {
        overlay.innerHTML = `
          <div class="welearn-modal welearn-task-modal">
            <h3>📖 课程目录 - ${currentCourseName}</h3>
            <p class="welearn-task-desc" style="color: #ef4444;">未找到可执行的任务</p>
            <div class="welearn-modal-footer">
              <button type="button" class="welearn-modal-cancel">关闭</button>
              <button type="button" class="welearn-btn-refresh">🔄 重新读取</button>
            </div>
          </div>
        `;
        overlay.querySelector('.welearn-modal-cancel')?.addEventListener('click', () => overlay.remove());
        overlay.querySelector('.welearn-btn-refresh')?.addEventListener('click', () => {
          showLoading();
          refreshDirectory();
        });
        return;
      }

      // 检查是否有之前保存的任务选择
      const savedTaskIds = (tasksCache && tasksCache.courseName === currentCourseName) 
        ? tasksCache.tasks.map(t => t.id) 
        : [];

      const tasksHtml = generateTasksHtml(availableTasks, savedTaskIds);
      const cacheTime = isFromCache && cache?.timestamp 
        ? new Date(cache.timestamp).toLocaleString('zh-CN') 
        : '';

      overlay.innerHTML = `
        <div class="welearn-modal welearn-task-modal">
          <h3>📖 课程目录 - ${currentCourseName}</h3>
          ${showMismatchWarning ? `
            <p class="welearn-warning-text">⚠️ 缓存的课程与当前课程不匹配,建议重新读取</p>
          ` : ''}
          <p class="welearn-task-desc">
            勾选要执行的任务,然后点击「⚡ 批量执行」按钮开始。
            ${isFromCache ? `<span class="welearn-cache-time">(缓存于 ${cacheTime})</span>` : ''}
          </p>
          
          <div class="welearn-task-actions-top">
            <button type="button" class="welearn-btn-select-all">全选未完成</button>
            <button type="button" class="welearn-btn-deselect-all">取消全选</button>
            <button type="button" class="welearn-btn-refresh">🔄 重新读取目录</button>
            <button type="button" class="welearn-btn-refresh-status">🔃 刷新完成状态</button>
          </div>
          
          <div class="welearn-task-container">
            ${tasksHtml}
          </div>
          
          <div class="welearn-task-summary">
            已选择: <span class="welearn-selected-count">0</span> 个任务
          </div>
          
          <div class="welearn-modal-footer">
            <button type="button" class="welearn-modal-cancel">取消</button>
            <button type="button" class="welearn-modal-confirm" disabled>✓ 确认选择</button>
          </div>
        </div>
      `;

      bindTaskListEvents(overlay, currentCourseName, availableTasks);
    };

    // 从页面刷新读取目录(以页面为准,清理错误的本地记录)
    const refreshDirectory = async () => {
      showLoading();
      
      // 等待展开所有目录
      await expandAllCategories();
      
      // 使用页面真实状态,忽略本地记录
      const tasks = getCourseTaskList({ ignoreLocalCompleted: true });
      const availableTasks = tasks.filter(t => !t.isDisabled);
      
      // 清理本地记录中与页面状态不一致的任务
      const completed = loadBatchCompleted();
      const ourCompletedTasks = completed[currentCourseName] || [];
      if (ourCompletedTasks.length > 0) {
        const pageCompletedIds = tasks.filter(t => t.isCompleted).map(t => t.id);
        const tasksToRemove = ourCompletedTasks.filter(id => !pageCompletedIds.includes(id));
        
        if (tasksToRemove.length > 0) {
          completed[currentCourseName] = ourCompletedTasks.filter(id => !tasksToRemove.includes(id));
          if (completed[currentCourseName].length === 0) {
            delete completed[currentCourseName];
          }
          saveBatchCompleted(completed);
          console.log('[WeLearn-Go] 清理了本地完成记录中的错误任务:', tasksToRemove);
        }
      }
      
      // 保存到缓存
      saveCourseDirectoryCache(currentCourseId, currentCourseName, availableTasks);
      
      renderTaskList(availableTasks, false, false);
      showToast(`已读取 ${availableTasks.length} 个任务`, { duration: 2000 });
    };

    // 刷新完成状态(从页面重新扫描任务状态,以页面为准)
    const refreshCompletionStatus = async (cachedTasks) => {
      showLoading();
      
      // 重新扫描页面获取最新任务状态(忽略本地记录,只看页面真实状态)
      const freshTasks = getCourseTaskList({ ignoreLocalCompleted: true });
      const freshTaskMap = new Map(freshTasks.map(t => [t.id, t]));
      
      // 加载本地完成记录
      const completed = loadBatchCompleted();
      const ourCompletedTasks = completed[currentCourseName] || [];
      
      // 找出本地记录中标记完成但页面显示未完成的任务(需要清理)
      const tasksToRemove = [];
      
      // 更新任务的完成状态(只使用页面真实状态)
      const updatedTasks = cachedTasks.map(task => {
        const freshTask = freshTaskMap.get(task.id);
        const pageCompleted = freshTask?.isCompleted || false;
        
        // 如果本地记录说已完成,但页面显示未完成,需要清理
        if (ourCompletedTasks.includes(task.id) && !pageCompleted) {
          tasksToRemove.push(task.id);
        }
        
        return {
          ...task,
          isCompleted: pageCompleted
        };
      });
      
      // 清理本地记录中错误标记的任务
      if (tasksToRemove.length > 0 && completed[currentCourseName]) {
        completed[currentCourseName] = completed[currentCourseName].filter(id => !tasksToRemove.includes(id));
        if (completed[currentCourseName].length === 0) {
          delete completed[currentCourseName];
        }
        saveBatchCompleted(completed);
        console.log('[WeLearn-Go] 清理了本地完成记录中的错误任务:', tasksToRemove);
      }
      
      // 更新缓存
      saveCourseDirectoryCache(currentCourseId, currentCourseName, updatedTasks);
      
      renderTaskList(updatedTasks, false, true);
      
      // 统计完成数量(只计算页面真实状态)
      const completedCount = updatedTasks.filter(t => t.isCompleted).length;
      const cleanedMsg = tasksToRemove.length > 0 ? `,已清理 ${tasksToRemove.length} 条错误记录` : '';
      showToast(`已刷新完成状态 (${completedCount}/${updatedTasks.length} 已完成)${cleanedMsg}`, { duration: 3000 });
    };

    document.body.appendChild(overlay);
    
    // 点击遮罩关闭
    overlay.addEventListener('click', (e) => {
      if (e.target === overlay) {
        overlay.remove();
      }
    });

    // 如果强制刷新或没有缓存,直接读取
    if (forceRefresh || !hasCacheForCurrentCourse) {
      if (courseIdMismatch) {
        // 课程不匹配,显示警告并读取
        showLoading();
        await refreshDirectory();
      } else {
        // 无缓存,直接读取
        showLoading();
        await refreshDirectory();
      }
    } else {
      // 有缓存,先刷新完成状态
      await refreshCompletionStatus(cache.tasks);
    }
  };

  /** 绑定任务列表事件 */
  const bindTaskListEvents = (overlay, courseName, availableTasks) => {
    const taskCheckboxes = overlay.querySelectorAll('.welearn-task-checkbox:not([disabled])');
    const unitCheckboxes = overlay.querySelectorAll('.welearn-unit-checkbox');
    const selectedCountEl = overlay.querySelector('.welearn-selected-count');
    const confirmButton = overlay.querySelector('.welearn-modal-confirm');
    const cancelButton = overlay.querySelector('.welearn-modal-cancel');
    const selectAllBtn = overlay.querySelector('.welearn-btn-select-all');
    const deselectAllBtn = overlay.querySelector('.welearn-btn-deselect-all');
    const refreshBtn = overlay.querySelector('.welearn-btn-refresh');
    const refreshStatusBtn = overlay.querySelector('.welearn-btn-refresh-status');

    /** 更新选中数量和按钮状态 */
    const updateSelectionState = () => {
      const checkedCount = overlay.querySelectorAll('.welearn-task-checkbox:checked').length;
      selectedCountEl.textContent = checkedCount;
      confirmButton.disabled = checkedCount === 0;
      
      // 更新单元复选框状态
      unitCheckboxes.forEach(unitCb => {
        const unitContainer = unitCb.closest('.welearn-task-unit');
        const unitTasks = unitContainer?.querySelectorAll('.welearn-task-checkbox:not([disabled])') || [];
        const checkedInUnit = unitContainer?.querySelectorAll('.welearn-task-checkbox:checked').length || 0;
        
        unitCb.checked = unitTasks.length > 0 && checkedInUnit === unitTasks.length;
        unitCb.indeterminate = checkedInUnit > 0 && checkedInUnit < unitTasks.length;
      });
    };

    // 初始化选中状态
    updateSelectionState();

    // 任务复选框事件
    taskCheckboxes.forEach(cb => {
      cb.addEventListener('change', updateSelectionState);
    });

    // 单元复选框事件
    unitCheckboxes.forEach(unitCb => {
      unitCb.addEventListener('change', () => {
        const unitContainer = unitCb.closest('.welearn-task-unit');
        const unitTasks = unitContainer?.querySelectorAll('.welearn-task-checkbox:not([disabled])') || [];
        unitTasks.forEach(cb => {
          cb.checked = unitCb.checked;
        });
        updateSelectionState();
      });
    });

    // 全选按钮
    selectAllBtn?.addEventListener('click', () => {
      taskCheckboxes.forEach(cb => { cb.checked = true; });
      updateSelectionState();
    });

    // 取消全选按钮
    deselectAllBtn?.addEventListener('click', () => {
      taskCheckboxes.forEach(cb => { cb.checked = false; });
      updateSelectionState();
    });

    // 重新读取按钮
    refreshBtn?.addEventListener('click', () => {
      showTaskSelectorModal(true);
      overlay.remove();
    });

    // 刷新完成状态按钮 - 重新扫描页面获取最新完成状态(以页面为准)
    refreshStatusBtn?.addEventListener('click', async () => {
      refreshStatusBtn.disabled = true;
      refreshStatusBtn.textContent = '刷新中...';
      
      // 保存当前选中的任务ID
      const checkedTaskIds = [];
      overlay.querySelectorAll('.welearn-task-checkbox:checked').forEach(cb => {
        checkedTaskIds.push(cb.dataset.taskId);
      });
      
      // 重新扫描页面获取最新任务状态(忽略本地记录,只看页面真实状态)
      const freshTasks = getCourseTaskList({ ignoreLocalCompleted: true });
      const freshTaskMap = new Map(freshTasks.map(t => [t.id, t]));
      
      // 加载本地完成记录
      const completed = loadBatchCompleted();
      const ourCompletedTasks = completed[courseName] || [];
      
      // 找出本地记录中标记完成但页面显示未完成的任务(需要清理)
      const tasksToRemove = [];
      
      // 更新任务列表中的完成状态
      overlay.querySelectorAll('.welearn-task-item').forEach(item => {
        const checkbox = item.querySelector('.welearn-task-checkbox');
        if (!checkbox) return;
        
        const taskId = checkbox.dataset.taskId;
        const freshTask = freshTaskMap.get(taskId);
        
        // 页面真实的完成状态(不考虑本地记录)
        const pageCompleted = freshTask?.isCompleted || false;
        const wasCompleted = item.classList.contains('completed');
        const wasInLocalRecord = ourCompletedTasks.includes(taskId);
        
        // 如果本地记录说已完成,但页面显示未完成,需要清理本地记录
        if (wasInLocalRecord && !pageCompleted) {
          tasksToRemove.push(taskId);
        }
        
        if (pageCompleted && !wasCompleted) {
          // 页面显示已完成
          item.classList.add('completed');
          checkbox.checked = false;
          checkbox.disabled = true;
          
          // 更新徽章为已完成(绿色)
          let badge = item.querySelector('.welearn-task-badge');
          if (!badge) {
            badge = document.createElement('span');
            item.appendChild(badge);
          }
          badge.className = 'welearn-task-badge';
          badge.textContent = '✓ 已完成';
        } else if (!pageCompleted && wasCompleted) {
          // 页面显示未完成(之前可能是本地记录标记的)
          item.classList.remove('completed');
          checkbox.disabled = false;
          
          // 更新徽章为待完成(黄色)
          let badge = item.querySelector('.welearn-task-badge');
          if (!badge) {
            badge = document.createElement('span');
            item.appendChild(badge);
          }
          badge.className = 'welearn-task-badge pending';
          badge.textContent = '○ 待完成';
          
          // 恢复之前的选中状态
          if (checkedTaskIds.includes(taskId)) {
            checkbox.checked = true;
          }
        }
      });
      
      // 清理本地记录中错误标记的任务
      if (tasksToRemove.length > 0 && completed[courseName]) {
        completed[courseName] = completed[courseName].filter(id => !tasksToRemove.includes(id));
        if (completed[courseName].length === 0) {
          delete completed[courseName];
        }
        saveBatchCompleted(completed);
        console.log('[WeLearn-Go] 清理了本地完成记录中的错误任务:', tasksToRemove);
      }
      
      // 更新缓存中的任务状态(使用页面真实状态)
      const currentCourseId = getCourseId();
      const validTasks = freshTasks.filter(t => !t.isDisabled);
      saveCourseDirectoryCache(currentCourseId, courseName, validTasks);
      
      // 计算完成数量(只计算页面真实状态)
      const completedCount = validTasks.filter(t => t.isCompleted).length;
      
      updateSelectionState();
      refreshStatusBtn.disabled = false;
      refreshStatusBtn.textContent = '🔃 刷新完成状态';
      
      const cleanedMsg = tasksToRemove.length > 0 ? `,已清理 ${tasksToRemove.length} 条错误记录` : '';
      showToast(`已刷新完成状态 (${completedCount}/${validTasks.length} 已完成)${cleanedMsg}`, { duration: 3000 });
    });

    // 取消按钮
    cancelButton?.addEventListener('click', () => {
      overlay.remove();
    });

    // 确认选择按钮
    confirmButton?.addEventListener('click', () => {
      const tasks = [];
      overlay.querySelectorAll('.welearn-task-checkbox:checked').forEach(cb => {
        tasks.push({
          id: cb.dataset.taskId,
          title: cb.dataset.title
        });
      });

      if (tasks.length === 0) {
        showToast('请至少选择一个任务');
        return;
      }

      // 保存选择的任务到全局变量和缓存
      selectedBatchTasks = tasks;
      selectedCourseName = courseName;
      saveBatchTasksCache(courseName, tasks);
      
      overlay.remove();
      showToast(`已选择 ${tasks.length} 个任务,点击「⚡ 批量执行」开始`, { duration: 3000 });
      
      updateBatchButtonState();
    });
  };

  /** 显示恢复批量任务提示 */
  const showBatchTasksRecoveryPrompt = () => {
    const tasksCache = loadBatchTasksCache();
    if (!tasksCache || !tasksCache.tasks || tasksCache.tasks.length === 0) return;
    
    const currentCourseName = getCourseName();
    const isSameCourse = tasksCache.courseName === currentCourseName;
    const cacheTime = new Date(tasksCache.timestamp).toLocaleString('zh-CN');
    
    const overlay = document.createElement('div');
    overlay.className = 'welearn-modal-overlay welearn-recovery-prompt';
    overlay.innerHTML = `
      <div class="welearn-modal welearn-recovery-modal">
        <h3>📋 发现未完成的批量任务</h3>
        <p>
          上次选择了 <strong>${tasksCache.tasks.length}</strong> 个任务
          ${!isSameCourse ? `<br><span class="welearn-warning-text">⚠️ 来自其他课程: ${tasksCache.courseName}</span>` : ''}
        </p>
        <p class="welearn-cache-time">保存于: ${cacheTime}</p>
        <div class="welearn-modal-footer">
          <button type="button" class="welearn-modal-cancel">忽略</button>
          <button type="button" class="welearn-modal-confirm">恢复任务列表</button>
        </div>
      </div>
    `;
    
    document.body.appendChild(overlay);
    
    overlay.querySelector('.welearn-modal-cancel')?.addEventListener('click', () => {
      clearBatchTasksCache();
      overlay.remove();
      showToast('已忽略,任务列表已清除');
    });
    
    overlay.querySelector('.welearn-modal-confirm')?.addEventListener('click', () => {
      // 恢复任务列表
      selectedBatchTasks = tasksCache.tasks;
      selectedCourseName = tasksCache.courseName;
      updateBatchButtonState();
      overlay.remove();
      showToast(`已恢复 ${tasksCache.tasks.length} 个任务,点击「⚡ 批量执行」开始`, { duration: 3000 });
    });
    
    overlay.addEventListener('click', (e) => {
      if (e.target === overlay) {
        // 点击背景只关闭对话框,不清除缓存(下次还会提示)
        overlay.remove();
      }
    });
  };

  /** 更新批量执行按钮状态 */
  const updateBatchButtonState = () => {
    const batchBtn = document.querySelector('.welearn-batch-btn');
    if (batchBtn) {
      if (selectedBatchTasks.length > 0) {
        batchBtn.textContent = `⚡ 执行 (${selectedBatchTasks.length})`;
        batchBtn.style.boxShadow = '0 0 0 2px rgba(56, 189, 248, 0.5), 0 6px 14px rgba(245, 158, 11, 0.3)';
      } else {
        batchBtn.textContent = '⚡ 批量执行';
        batchBtn.style.boxShadow = '';
      }
    }
  };

  /** 执行已选择的批量任务 */
  const executeBatchTasks = () => {
    if (selectedBatchTasks.length === 0) {
      showToast('请先点击「📖 查看目录」选择要执行的任务', { duration: 3000 });
      return;
    }
    
    const taskCount = selectedBatchTasks.length;
    const courseName = selectedCourseName;
    
    // 清空已选任务(防止重复执行)
    const tasksToExecute = [...selectedBatchTasks];
    selectedBatchTasks = [];
    selectedCourseName = '';
    updateBatchButtonState();
    
    // 开始执行
    startBatchExecution(tasksToExecute, courseName);
  };

  /** 开始批量执行任务 */
  const startBatchExecution = (tasks, courseName) => {
    if (tasks.length === 0) {
      showToast('所有任务已完成!');
      clearBatchModeState();
      return;
    }

    batchModeActive = true;
    batchTaskQueue = [...tasks];
    
    // 清除任务选择缓存(任务已开始执行,不需要恢复提示了)
    clearBatchTasksCache();
    
    // 保存状态到 localStorage(用于页面跳转后恢复)
    saveBatchModeState({
      active: true,
      queue: batchTaskQueue,
      courseName: courseName,
      currentIndex: 0,
      totalTasks: tasks.length,
      phase: 'navigating' // 'navigating' | 'filling' | 'submitting' | 'waiting_next'
    });

    showBatchProgressIndicator(tasks.length, 0);
    showToast(`开始执行 ${tasks.length} 个任务,请勿操作页面...`, { duration: 3000 });
    
    // 执行第一个任务
    setTimeout(() => {
      executeNextTask();
    }, 1000);
  };

  /** 显示批量进度指示器 */
  const showBatchProgressIndicator = (total, current) => {
    // 移除已有的指示器
    document.querySelector('.welearn-batch-progress')?.remove();
    
    const indicator = document.createElement('div');
    indicator.className = 'welearn-batch-progress';
    indicator.innerHTML = `
      <span>批量执行中: <span class="progress-text">${current + 1}/${total}</span></span>
      <button type="button" class="welearn-batch-stop" style="margin-left: 12px; background: rgba(239, 68, 68, 0.3); border: 1px solid rgba(239, 68, 68, 0.5); color: #f87171; padding: 4px 12px; border-radius: 8px; cursor: pointer; font-weight: 600;">停止</button>
    `;
    
    indicator.querySelector('.welearn-batch-stop')?.addEventListener('click', () => {
      if (confirm('确定要停止批量执行吗?已完成的任务不会撤销。')) {
        stopBatchExecution();
      }
    });
    
    document.body.appendChild(indicator);
  };

  /** 更新批量进度 */
  const updateBatchProgress = () => {
    const state = loadBatchModeState();
    if (!state) return;
    
    const indicator = document.querySelector('.welearn-batch-progress .progress-text');
    if (indicator) {
      const completed = state.totalTasks - state.queue.length;
      indicator.textContent = `${completed + 1}/${state.totalTasks}`;
    } else {
      // 如果指示器不存在,重新创建
      showBatchProgressIndicator(state.totalTasks, state.totalTasks - state.queue.length);
    }
  };

  /** 停止批量执行 */
  const stopBatchExecution = () => {
    batchModeActive = false;
    batchTaskQueue = [];
    currentBatchTask = null;
    clearBatchModeState();
    document.querySelector('.welearn-batch-progress')?.remove();
    showToast('批量执行已停止');
  };

  /** 执行下一个任务 */
  const executeNextTask = () => {
    const state = loadBatchModeState();
    if (!state || !state.active || state.queue.length === 0) {
      finishBatchExecution();
      return;
    }

    const task = state.queue[0];
    currentBatchTask = task;
    
    console.log('[WeLearn-Go] 批量执行: 开始任务', task.title);
    showToast(`正在执行: ${task.title}`, { duration: 2000 });

    // 尝试多种方式启动任务
    
    // 方式1: 直接调用 StartSCO 函数 (新版页面)
    if (typeof window.StartSCO === 'function') {
      console.log('[WeLearn-Go] 批量执行: 使用 StartSCO 启动', task.id);
      state.phase = 'navigating';
      saveBatchModeState(state);
      window.StartSCO(task.id);
      return;
    }

    // 方式2: 通过点击元素 (旧版页面或备用方案)
    // 查找对应的任务项: li[onclick*="StartSCO('ITEM-xxx')"]
    let taskElement = document.querySelector(`li[onclick*="StartSCO('${task.id}')"]`);
    
    // 如果找不到,尝试其他选择器
    if (!taskElement) {
      taskElement = document.querySelector(`li[id="${task.id}"], [data-sco="${task.id}"]`);
    }
    
    if (!taskElement) {
      console.warn('[WeLearn-Go] 批量执行: 未找到任务元素', task.id);
      // 跳过这个任务,继续下一个
      skipCurrentTask('未找到任务元素');
      return;
    }

    // 点击任务进入学习页面
    // 优先使用 onclick 属性
    const onclickAttr = taskElement.getAttribute('onclick');
    if (onclickAttr && onclickAttr.includes('StartSCO')) {
      state.phase = 'navigating';
      saveBatchModeState(state);
      
      // 直接执行 onclick
      taskElement.click();
      // 页面会跳转,在新页面中通过 checkAndResumeBatchMode 继续执行
    } else {
      // 尝试点击内部链接
      const link = taskElement.querySelector('a');
      if (link) {
        state.phase = 'navigating';
        saveBatchModeState(state);
        link.click();
      } else {
        skipCurrentTask('未找到任务链接');
      }
    }
  };

  /** 跳过当前任务 */
  const skipCurrentTask = (reason) => {
    const state = loadBatchModeState();
    if (!state) return;

    console.warn('[WeLearn-Go] 批量执行: 跳过任务', state.queue[0]?.title, reason);
    
    // 移除当前任务
    state.queue.shift();
    state.currentIndex++;
    state.phase = 'navigating';
    saveBatchModeState(state);

    // 短暂延迟后执行下一个
    setTimeout(() => {
      executeNextTask();
    }, 1000);
  };

  /** 完成当前任务 */
  const completeCurrentTask = () => {
    const state = loadBatchModeState();
    if (!state) return;

    const task = state.queue[0];
    if (task) {
      markTaskCompleted(task.id, state.courseName);
      console.log('[WeLearn-Go] 批量执行: 完成任务', task.title);
      showToast(`✓ 已完成: ${task.title}`, { duration: 2000 });
    }

    // 移除当前任务
    state.queue.shift();
    state.currentIndex++;
    saveBatchModeState(state);
    
    // 更新进度显示
    updateBatchProgress();

    // 检查是否还有更多任务
    if (state.queue.length === 0) {
      setTimeout(() => {
        finishBatchExecution();
      }, 1500);
      return;
    }

    // 任务间隔等待 30 秒
    const TASK_INTERVAL = 30 * 1000;
    showCountdownToast('任务间隔等待中', TASK_INTERVAL, '即将执行下一个任务...');
    
    setTimeout(() => {
      returnToCoursePage();
    }, TASK_INTERVAL);
  };

  /** 返回课程主页 */
  const returnToCoursePage = () => {
    const state = loadBatchModeState();
    if (state) {
      state.phase = 'returning';
      saveBatchModeState(state);
    }

    console.log('[WeLearn-Go] 批量执行: 返回课程主页');

    // 方法1:查找页面上的返回按钮 (.main-goback)
    const mainGoback = document.querySelector('.main-goback');
    if (mainGoback && mainGoback.offsetParent !== null) {
      console.log('[WeLearn-Go] 批量执行: 点击 .main-goback 返回');
      mainGoback.click();
      return;
    }

    // 方法2:查找面包屑或返回链接
    const backLinks = document.querySelectorAll(
      'a[href*="StudyCourse"], a[href*="course_info"], a[href*="CourseIndex"], .breadcrumb a, .back-link, .back-btn, .goback'
    );
    for (const link of backLinks) {
      if (link.offsetParent !== null) { // 可见
        console.log('[WeLearn-Go] 批量执行: 点击返回链接');
        link.click();
        return;
      }
    }

    // 方法3:通过 body 的 data-classid 获取 classid
    const bodyClassid = document.body.getAttribute('data-classid');
    const urlParams = new URLSearchParams(window.location.search);
    const cid = urlParams.get('cid');
    const classid = urlParams.get('classid') || bodyClassid;
    
    if (cid && classid) {
      console.log('[WeLearn-Go] 批量执行: 通过 URL 返回课程页面');
      window.location.href = `https://welearn.sflep.com/student/course_info.aspx?cid=${cid}&classid=${classid}`;
      return;
    }

    // 方法4:使用浏览器后退
    console.log('[WeLearn-Go] 批量执行: 使用浏览器后退');
    window.history.back();
  };

  /** 完成批量执行 */
  const finishBatchExecution = () => {
    batchModeActive = false;
    batchTaskQueue = [];
    currentBatchTask = null;
    clearBatchModeState();
    clearBatchTasksCache();  // 清除任务选择缓存
    document.querySelector('.welearn-batch-progress')?.remove();
    
    showToast('🎉 所有任务已完成!', { duration: 5000 });
  };

  /** 检查并恢复批量模式(页面加载时调用) */
  const checkAndResumeBatchMode = () => {
    const state = loadBatchModeState();
    
    if (!state || !state.active) {
      return false;
    }

    // 检查是否是真正的异常中断(超过3分钟没有更新)
    const ABNORMAL_TIMEOUT = 3 * 60 * 1000; // 3分钟
    const timeSinceLastUpdate = Date.now() - (state.lastUpdate || 0);
    
    if (timeSinceLastUpdate < ABNORMAL_TIMEOUT) {
      // 批量任务仍在正常进行中,不处理
      console.log('[WeLearn-Go] 批量模式: 任务仍在进行中', {
        timeSinceLastUpdate: Math.round(timeSinceLastUpdate / 1000) + '秒'
      });
      return false;
    }

    // 超过3分钟没有更新,认为是异常中断
    const remainingCount = state.queue?.length || 0;
    console.log('[WeLearn-Go] 批量模式: 检测到异常中断的批量执行', {
      remainingTasks: remainingCount,
      phase: state.phase,
      courseName: state.courseName,
      timeSinceLastUpdate: Math.round(timeSinceLastUpdate / 1000) + '秒'
    });
    
    // 将剩余任务保存到任务选择缓存,方便用户手动恢复
    if (remainingCount > 0 && state.queue && state.courseName) {
      saveBatchTasksCache(state.courseName, state.queue);
    }
    
    // 清除批量执行状态
    clearBatchModeState();
    
    // 不显示toast提示,让任务恢复对话框来处理
    return false;
  };

  /** 执行填写和提交 */
  const executeFillAndSubmit = async () => {
    const state = loadBatchModeState();
    if (!state || !state.active) return;

    try {
      console.log('[WeLearn-Go] 批量执行: 开始填写');
      state.phase = 'filling';
      saveBatchModeState(state);

      // 等待 iframe 加载(最多等待 10 秒)
      await waitForIframeReady();
      
      // 等待练习内容加载完成(最多等待 15 秒)
      await waitForExerciseContent();

      // 统计题目数量,用于计算等待时间
      const questionCount = countQuestions();
      console.log('[WeLearn-Go] 批量执行: 检测到题目数量:', questionCount);
      
      // 执行填写
      const result = fillAll({ enableSoftErrors: false });
      triggerIframeFill(false);

      // 等待填写完成(给异步操作足够时间)
      await new Promise(resolve => setTimeout(resolve, 2000));
      
      // 二次填充:有些元素可能是异步加载的
      const result2 = fillAll({ enableSoftErrors: false });
      triggerIframeFill(false);
      
      // 再等待一下
      await new Promise(resolve => setTimeout(resolve, 1000));

      // 检查是否需要处理多页(Next 按钮)- 最多处理 20 页
      await handleMultiplePages();

      // 计算刷时长等待时间(根据当前模式配置)
      const durationMode = loadDurationMode();
      const durationConfig = getDurationConfig();
      const calculatedTime = calculateDurationTime(questionCount);
      
      // 只有非关闭模式才等待刷时长
      if (durationMode !== 'off' && calculatedTime > 0) {
        console.log('[WeLearn-Go] 批量执行: 等待刷时长', {
          mode: durationConfig.name,
          questionCount,
          waitTime: Math.round(calculatedTime / 1000) + '秒'
        });
        
        // 显示刷时长倒计时(包含模式信息)
        const modeIcon = durationMode === 'fast' ? '🚀' : '🐢';
        showCountdownToast(`${modeIcon} 正在刷时长`, calculatedTime, `${durationConfig.name}模式 | ${questionCount} 道题目`);
        
        // 等待刷时长,使用配置的心跳间隔
        await waitWithHeartbeat(calculatedTime);
      } else {
        console.log('[WeLearn-Go] 批量执行: 刷时长已关闭,直接提交');
        showToast('⏭️ 刷时长已关闭,直接提交', { duration: 1500 });
        await new Promise(resolve => setTimeout(resolve, 500));
      }

      // 提交
      const latestState = loadBatchModeState();
      if (latestState) {
        latestState.phase = 'submitting';
        saveBatchModeState(latestState);
      }
      
      await performSubmit();
    } catch (error) {
      console.error('[WeLearn-Go] 批量执行: 填写过程出错', error);
      showToast('填写过程出错,跳过当前任务', { duration: 3000 });
      // 出错时也要继续下一个任务,避免卡住
      completeCurrentTask();
    }
  };

  /** 带心跳的等待(定期更新状态时间戳,防止被误判为异常中断) */
  const waitWithHeartbeat = (totalMs) => {
    return new Promise((resolve) => {
      const durationConfig = getDurationConfig();
      const heartbeatInterval = durationConfig.intervalTime; // 使用配置的心跳间隔
      let elapsed = 0;
      
      const heartbeat = setInterval(() => {
        elapsed += heartbeatInterval;
        
        // 更新状态时间戳
        const state = loadBatchModeState();
        if (state) {
          saveBatchModeState(state);
        }
        
        if (elapsed >= totalMs) {
          clearInterval(heartbeat);
          resolve();
        }
      }, heartbeatInterval);
      
      // 如果总时间小于心跳间隔,直接等待
      if (totalMs <= heartbeatInterval) {
        clearInterval(heartbeat);
        setTimeout(resolve, totalMs);
      } else {
        // 等待剩余时间
        setTimeout(() => {
          clearInterval(heartbeat);
          resolve();
        }, totalMs);
      }
    });
  };
  
  /** 统计当前页面的题目数量 */
  const countQuestions = () => {
    let count = 0;
    
    // 统计各种题型
    const blanks = document.querySelectorAll('et-blank, .blank, input[type="text"], [contenteditable="true"]');
    const toggles = document.querySelectorAll('et-toggle');
    const choices = document.querySelectorAll('et-item, .choice-item, input[type="radio"], input[type="checkbox"]');
    const textareas = document.querySelectorAll('textarea');
    
    // 也检查 iframe 内的内容
    const iframes = document.querySelectorAll('iframe');
    iframes.forEach(iframe => {
      try {
        const doc = iframe.contentDocument;
        if (doc) {
          count += doc.querySelectorAll('et-blank, .blank, input[type="text"]').length;
          count += doc.querySelectorAll('et-toggle').length;
          count += doc.querySelectorAll('et-item, .choice-item').length;
          count += doc.querySelectorAll('textarea').length;
        }
      } catch (e) { /* 跨域忽略 */ }
    });
    
    count += blanks.length + toggles.length + Math.ceil(choices.length / 4) + textareas.length;
    
    // 至少返回 10(保证有基础等待时间)
    return Math.max(count, 10);
  };
  
  /** 显示倒计时 Toast */
  const showCountdownToast = (title, totalMs, subtitle = '') => {
    // 移除已有的倒计时 toast
    document.querySelector('.welearn-countdown-toast')?.remove();
    
    const toast = document.createElement('div');
    toast.className = 'welearn-countdown-toast';
    toast.style.cssText = `
      position: fixed;
      top: 50%;
      left: 50%;
      transform: translate(-50%, -50%);
      background: rgba(0, 0, 0, 0.85);
      color: white;
      padding: 24px 32px;
      border-radius: 12px;
      z-index: 100001;
      text-align: center;
      min-width: 200px;
      box-shadow: 0 4px 20px rgba(0,0,0,0.3);
    `;
    
    const remainingSeconds = Math.ceil(totalMs / 1000);
    
    toast.innerHTML = `
      <div style="font-size: 14px; color: #aaa; margin-bottom: 8px;">⏱️ ${title}</div>
      <div style="font-size: 36px; font-weight: bold; margin-bottom: 8px;" class="countdown-number">${remainingSeconds}</div>
      <div style="font-size: 12px; color: #888;">${subtitle}</div>
    `;
    
    document.body.appendChild(toast);
    
    // 更新倒计时
    let remaining = remainingSeconds;
    const interval = setInterval(() => {
      remaining--;
      const numberEl = toast.querySelector('.countdown-number');
      if (numberEl) {
        numberEl.textContent = remaining;
      }
      if (remaining <= 0) {
        clearInterval(interval);
        toast.remove();
      }
    }, 1000);
    
    // 确保在总时间后移除
    setTimeout(() => {
      clearInterval(interval);
      toast.remove();
    }, totalMs);
  };

  /** 等待 iframe 准备就绪 */
  const waitForIframeReady = () => {
    return new Promise((resolve) => {
      const maxWait = 10000;
      const startTime = Date.now();
      
      const check = () => {
        const iframes = document.querySelectorAll('iframe');
        let ready = iframes.length === 0; // 没有 iframe 则直接就绪
        
        iframes.forEach(iframe => {
          try {
            if (iframe.contentDocument?.body) {
              ready = true;
            }
          } catch (e) {
            // 跨域 iframe,假设已就绪
            ready = true;
          }
        });

        if (ready || Date.now() - startTime > maxWait) {
          resolve();
        } else {
          setTimeout(check, 500);
        }
      };

      check();
    });
  };

  /** 等待练习内容加载完成 */
  const waitForExerciseContent = () => {
    return new Promise((resolve) => {
      const maxWait = 15000; // 最多等待 15 秒
      const startTime = Date.now();
      
      const check = () => {
        const contexts = getAccessibleDocuments();
        let hasContent = false;
        let elementCount = 0;
        
        for (const doc of contexts) {
          // 检查各种练习元素
          const fillings = doc.querySelectorAll('[data-controltype="filling"], [data-controltype="fillinglong"]');
          const choices = doc.querySelectorAll('[data-controltype="choice"]');
          const etItems = doc.querySelectorAll('et-item');
          const etBlanks = doc.querySelectorAll('et-blank');
          const etToggles = doc.querySelectorAll('et-toggle');
          const etTofs = doc.querySelectorAll('et-tof');
          const options = doc.querySelectorAll('ul[data-itemtype="options"]');
          
          elementCount += fillings.length + choices.length + etItems.length + 
                          etBlanks.length + etToggles.length + etTofs.length + options.length;
          
          if (elementCount > 0) {
            hasContent = true;
          }
        }
        
        console.log('[WeLearn-Go] waitForExerciseContent: 检测到练习元素数量:', elementCount);
        
        // 如果找到练习内容,或者超时,则返回
        if (hasContent || Date.now() - startTime > maxWait) {
          if (!hasContent) {
            console.warn('[WeLearn-Go] waitForExerciseContent: 等待超时,未检测到练习内容');
          }
          resolve();
        } else {
          setTimeout(check, 500);
        }
      };

      // 首次延迟 1 秒再检查(给 AngularJS 等框架初始化时间)
      setTimeout(check, 1000);
    });
  };

  /** 处理多页情况 */
  const handleMultiplePages = async () => {
    const maxPages = 20; // 最多处理 20 页
    let pageCount = 0;

    while (pageCount < maxPages) {
      // 查找 Next 按钮
      const nextButton = findNextButton();
      
      if (!nextButton) {
        console.log('[WeLearn-Go] 批量执行: 没有找到 Next 按钮,当前是最后一页');
        break;
      }

      console.log('[WeLearn-Go] 批量执行: 点击 Next 进入下一页');
      nextButton.click();
      pageCount++;

      // 等待页面切换
      await new Promise(resolve => setTimeout(resolve, 2000));
      
      // 不需要重新填写(按需求,第一页已填写所有问题)
      // 继续查找 Submit 或下一个 Next
    }
  };

  /** 查找 Next 按钮 */
  const findNextButton = () => {
    const contexts = getAccessibleDocuments();
    
    for (const doc of contexts) {
      // 查找各种可能的 Next 按钮
      const selectors = [
        'button:contains("Next")',
        'a:contains("Next")',
        '.next-btn',
        '.btn-next',
        '[class*="next"]',
        'button[ng-click*="next"]',
        'et-button[action*="next"]'
      ];

      // 直接文本匹配
      const allButtons = doc.querySelectorAll('button, a.btn, et-button button, .controls button');
      for (const btn of allButtons) {
        const text = btn.textContent?.trim().toLowerCase();
        if (text === 'next' || text === '下一页' || text === '下一步') {
          // 检查是否可见和可点击
          if (!btn.disabled && btn.offsetParent !== null) {
            return btn;
          }
        }
      }

      // AngularJS et-button
      const etButtons = doc.querySelectorAll('et-button');
      for (const etBtn of etButtons) {
        const action = etBtn.getAttribute('action') || '';
        if (action.includes('next') || action.includes('Next')) {
          const innerBtn = etBtn.querySelector('button');
          if (innerBtn && !innerBtn.disabled && etBtn.offsetParent !== null) {
            return innerBtn;
          }
        }
      }
    }

    return null;
  };

  /** 查找 Submit 按钮 */
  const findSubmitButton = () => {
    const contexts = getAccessibleDocuments();
    
    for (const doc of contexts) {
      // 直接文本匹配
      const allButtons = doc.querySelectorAll('button, a.btn, et-button button, .controls button');
      for (const btn of allButtons) {
        const text = btn.textContent?.trim().toLowerCase();
        if (text === 'submit' || text === '提交' || text === '提交答案') {
          if (!btn.disabled && btn.offsetParent !== null) {
            return btn;
          }
        }
      }

      // data-controltype="submit"
      const submitByAttr = doc.querySelector('[data-controltype="submit"]:not([disabled])');
      if (submitByAttr && submitByAttr.offsetParent !== null) {
        return submitByAttr;
      }

      // AngularJS et-button
      const etButtons = doc.querySelectorAll('et-button[action*="submit"]');
      for (const etBtn of etButtons) {
        if (!etBtn.classList.contains('ng-hide') && etBtn.offsetParent !== null) {
          const innerBtn = etBtn.querySelector('button');
          if (innerBtn && !innerBtn.disabled) {
            return innerBtn;
          }
        }
      }
    }

    return null;
  };

  /** 执行提交 */
  const performSubmit = async () => {
    const submitBtn = findSubmitButton();
    
    if (submitBtn) {
      console.log('[WeLearn-Go] 批量执行: 点击 Submit 按钮');
      submitBtn.click();
      
      // 等待提交完成
      await new Promise(resolve => setTimeout(resolve, 2000));
      
      // 检查是否提交成功(查找成功提示或确认界面)
      const isSuccess = await checkSubmitSuccess();
      
      if (isSuccess) {
        console.log('[WeLearn-Go] 批量执行: 提交成功');
        completeCurrentTask();
      } else {
        console.warn('[WeLearn-Go] 批量执行: 提交可能失败,继续下一个任务');
        completeCurrentTask(); // 暂时还是标记完成,避免卡住
      }
    } else {
      console.warn('[WeLearn-Go] 批量执行: 未找到 Submit 按钮');
      // 可能是已经提交过了,或者不需要提交
      completeCurrentTask();
    }
  };

  /** 检查提交是否成功 */
  const checkSubmitSuccess = async () => {
    // 等待结果显示
    await new Promise(resolve => setTimeout(resolve, 1000));
    
    const contexts = getAccessibleDocuments();
    for (const doc of contexts) {
      // 查找成功提示
      const successIndicators = doc.querySelectorAll('.success, .submitted, .complete, [class*="success"], [class*="submitted"]');
      if (successIndicators.length > 0) {
        return true;
      }
      
      // 查找错误提示
      const errorIndicators = doc.querySelectorAll('.error, .failed, [class*="error"], [class*="fail"]');
      if (errorIndicators.length > 0) {
        return false;
      }
    }
    
    // 默认认为成功
    return true;
  };

  // ==================== UI 组件 ====================

  /**
   * 显示 Toast 提示
   * @param {string} message - 提示消息(支持 HTML)
   * @param {Object} options - 配置选项
   * @param {number} options.duration - 显示时长(毫秒),0 表示不自动关闭
   * @param {boolean} options.html - 是否作为 HTML 渲染
   */
  const showToast = (message, { duration = 2500, html = false } = {}) => {
    const toast = document.createElement('div');
    toast.className = 'welearn-toast';
    if (html) {
      toast.innerHTML = message;
    } else {
      toast.textContent = message;
    }
    
    // 先添加到 DOM 以便计算高度
    document.body.appendChild(toast);
    
    // 计算当前已有 Toast 的总高度,让新 Toast 堆叠在下面
    // 包括所有 Toast(包括刚添加但还没有 visible 类的)
    const existingToasts = document.querySelectorAll('.welearn-toast');
    let topOffset = 18;
    existingToasts.forEach((t) => {
      if (t !== toast) {
        topOffset += t.offsetHeight + 10;
      }
    });
    toast.style.top = topOffset + 'px';
    
    requestAnimationFrame(() => {
      toast.classList.add('visible');
    });
    
    // Toast 移除时重新计算其他 Toast 的位置
    const removeToast = () => {
      toast.classList.remove('visible');
      setTimeout(() => {
        toast.remove();
        // 重新计算剩余 Toast 的位置
        const remainingToasts = document.querySelectorAll('.welearn-toast.visible');
        let newTop = 18;
        remainingToasts.forEach((t) => {
          t.style.top = newTop + 'px';
          newTop += t.offsetHeight + 10;
        });
      }, 300);
    };
    
    if (duration > 0 && Number.isFinite(duration)) {
      setTimeout(removeToast, duration);
    }
  };

  /** 清理页面上的所有 UI 元素 */
  const cleanupPageArtifacts = () => {
    document.querySelector('.welearn-panel')?.remove();
    document.querySelectorAll('.welearn-modal-overlay').forEach((node) => node.remove());
    document.querySelectorAll('.welearn-toast').forEach((node) => node.remove());
  };

  // ==================== 状态持久化 ====================

  /** 加载面板状态 */
  const loadPanelState = () => {
    try {
      const raw = localStorage.getItem(PANEL_STATE_KEY);
      return raw ? JSON.parse(raw) : {};
    } catch (error) {
      console.warn('WeLearn autofill: failed to load panel state', error);
      return {};
    }
  };

  /** 保存面板状态 */
  const savePanelState = (state) => {
    try {
      localStorage.setItem(PANEL_STATE_KEY, JSON.stringify(state));
    } catch (error) {
      console.warn('WeLearn autofill: failed to save panel state', error);
    }
  };

  // ==================== 样式定义 ====================

  /** 创建并注入样式 */
  const createStyles = () => {
    const css = `
      /* 主面板样式 */
      .welearn-panel {
        position: fixed;
        top: 120px;
        left: 24px;
        width: 340px;
        min-width: 340px;
        max-width: 540px;
        padding: 12px;
        background: rgba(27, 38, 56, 0.95);
        color: #f8fafc;
        border-radius: 16px;
        box-shadow: 0 12px 30px rgba(0, 0, 0, 0.35);
        z-index: 2147483647;
        box-sizing: border-box;
        font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
        backdrop-filter: blur(6px);
        transition: width 0.25s ease, height 0.25s ease, min-width 0.25s ease, max-width 0.25s ease, padding 0.25s ease;
        overflow: hidden;
      }
      .welearn-body {
        display: flex;
        flex-direction: column;
        gap: 8px;
        opacity: 1;
        transition: opacity 0.15s ease 0.1s;
        min-width: 316px;
        margin: 0;
        padding: 0;
      }
      .welearn-panel.minimized .welearn-body {
        opacity: 0;
        pointer-events: none;
        transition: opacity 0.1s ease;
      }
      body.welearn-dragging, body.welearn-dragging * {
        user-select: none !important;
      }
      .welearn-drag-zone {
        position: absolute;
        top: 0;
        left: 0;
        right: 44px;
        height: 44px;
        cursor: move;
        user-select: none;
        z-index: 5;
      }
      .welearn-panel h3 {
        margin: 0 0 8px;
        font-size: 16px;
        font-weight: 600;
        display: flex;
        align-items: center;
        gap: 6px;
        cursor: move;
        user-select: none;
        white-space: nowrap;
        position: relative;
        z-index: 6;
        pointer-events: none;
      }
      .welearn-panel h3 span {
        font-size: 13px;
        font-weight: 500;
        color: #cbd5e1;
        pointer-events: none;
      }
      .welearn-update-hint {
        font-size: 10px;
        font-weight: 600;
        color: #fbbf24;
        background: rgba(251, 191, 36, 0.15);
        padding: 2px 6px;
        border-radius: 8px;
        margin-left: 6px;
        text-decoration: none;
        pointer-events: auto;
        cursor: pointer;
        animation: welearn-pulse 2s ease-in-out infinite;
        transition: background 0.2s ease, transform 0.2s ease;
      }
      .welearn-update-hint:hover {
        background: rgba(251, 191, 36, 0.25);
        transform: scale(1.05);
      }
      @keyframes welearn-pulse {
        0%, 100% { opacity: 1; }
        50% { opacity: 0.7; }
      }
      .welearn-actions {
        display: grid;
        grid-template-columns: 1fr 1fr;
        align-items: stretch;
        gap: 8px;
        margin: 8px 0 10px;
        min-width: 280px;
      }
      .welearn-actions .welearn-start {
        grid-column: 1 / -1;
        width: 100%;
        background: linear-gradient(135deg, #38bdf8, #6366f1);
        color: #0b1221;
        border: none;
        border-radius: 16px;
        padding: 10px 12px;
        font-weight: 700;
        font-size: 14px;
        cursor: pointer;
        box-shadow: 0 8px 18px rgba(99, 102, 241, 0.35);
        transition: transform 0.12s ease, box-shadow 0.12s ease, filter 0.12s ease;
      }
      .welearn-actions .welearn-start:hover {
        transform: translateY(-1px);
        box-shadow: 0 10px 22px rgba(56, 189, 248, 0.32);
        filter: brightness(1.03);
      }
      .welearn-actions .welearn-start:disabled {
        cursor: not-allowed;
        opacity: 0.65;
        box-shadow: none;
      }
      .welearn-toggle-btn {
        background: rgba(148, 163, 184, 0.15);
        color: #94a3b8;
        border: 1px solid rgba(148, 163, 184, 0.25);
        border-radius: 16px;
        padding: 10px 12px;
        font-weight: 600;
        font-size: 13px;
        cursor: pointer;
        box-shadow: none;
        transition: transform 0.12s ease, background 0.2s ease, color 0.2s ease, border-color 0.2s ease, box-shadow 0.2s ease, filter 0.12s ease;
        white-space: nowrap;
      }
      .welearn-toggle-btn:hover {
        background: rgba(148, 163, 184, 0.25);
        transform: translateY(-1px);
      }
      .welearn-toggle-btn.active {
        background: linear-gradient(135deg, #38bdf8, #6366f1);
        background-origin: border-box;
        background-clip: padding-box;
        color: #0b1221;
        border-color: transparent;
        box-shadow: 0 6px 14px rgba(99, 102, 241, 0.3);
      }
      .welearn-toggle-btn.active:hover {
        transform: translateY(-1px);
        box-shadow: 0 8px 18px rgba(56, 189, 248, 0.32);
        filter: brightness(1.03);
      }
      .welearn-footer {
        font-size: 12px;
        color: #94a3b8;
        display: flex;
        flex-wrap: wrap;
        justify-content: center;
        align-items: center;
        gap: 8px;
        margin: 8px 0 0 0;
        padding: 0;
      }
      .welearn-footer > span {
        width: 100%;
        text-align: center;
        margin: 0;
        padding: 0;
      }
      .welearn-footer a {
        color: #38bdf8;
        text-decoration: none;
        white-space: nowrap;
      }
      .welearn-footer a:hover {
        opacity: 0.8;
      }
      .welearn-support {
        background: rgba(56, 189, 248, 0.14);
        color: #38bdf8;
        border: 1px solid rgba(56, 189, 248, 0.35);
        border-radius: 16px;
        padding: 8px 12px;
        margin: 0;
        cursor: pointer;
        font-weight: 700;
        font-size: 12px;
        transition: transform 0.12s ease, box-shadow 0.12s ease, background 0.12s ease;
      }
      .welearn-support:hover {
        background: rgba(56, 189, 248, 0.22);
        box-shadow: 0 6px 16px rgba(56, 189, 248, 0.28);
        transform: translateY(-1px);
      }
      .welearn-stats-row {
        display: flex;
        align-items: center;
        justify-content: space-between;
        gap: 8px;
        margin-top: 6px;
        padding: 6px 10px;
        background: rgba(148, 163, 184, 0.08);
        border-radius: 10px;
        font-size: 11px;
        color: #94a3b8;
      }
      .welearn-error-stats {
        flex: 1;
        line-height: 1.4;
      }
      .welearn-error-stats b {
        color: #38bdf8;
        margin: 0 2px;
      }
      .welearn-clear-stats {
        background: rgba(239, 68, 68, 0.15);
        color: #f87171;
        border: 1px solid rgba(239, 68, 68, 0.3);
        border-radius: 8px;
        padding: 4px 8px;
        font-size: 10px;
        font-weight: 600;
        cursor: pointer;
        transition: background 0.15s ease, transform 0.1s ease;
        white-space: nowrap;
      }
      .welearn-clear-stats:hover {
        background: rgba(239, 68, 68, 0.25);
        transform: translateY(-1px);
      }
      .welearn-weights-row {
        display: flex;
        flex-wrap: wrap;
        align-items: center;
        gap: 6px;
        margin-top: 6px;
        padding: 6px 10px;
        background: rgba(148, 163, 184, 0.08);
        border-radius: 10px;
        font-size: 11px;
        color: #94a3b8;
      }
      .welearn-weights-row label {
        display: inline-flex;
        align-items: center;
        gap: 4px;
        white-space: nowrap;
        margin: 0 !important;
        margin-bottom: 0 !important;
        font-weight: normal !important;
        max-width: none !important;
      }
      .welearn-weight-text {
        display: inline-flex;
        align-items: center;
        height: 22px;
        line-height: 1;
        margin: 0 !important;
      }
      .welearn-weights-row input {
        width: 32px;
        height: 22px;
        padding: 0 4px;
        margin: 0 !important;
        background: rgba(30, 41, 59, 0.8);
        border: 1px solid rgba(148, 163, 184, 0.3);
        border-radius: 4px;
        color: #e2e8f0;
        font-size: 11px;
        font-family: inherit;
        text-align: center;
        line-height: 1;
        box-sizing: border-box;
        vertical-align: middle;
        -moz-appearance: textfield;
        -webkit-appearance: none;
        appearance: none;
      }
      .welearn-weights-row input::-webkit-outer-spin-button,
      .welearn-weights-row input::-webkit-inner-spin-button {
        -webkit-appearance: none;
        margin: 0;
      }
      .welearn-weights-row input:focus {
        outline: none;
        border-color: #38bdf8;
      }
      .welearn-weights-row input.error {
        border-color: #ef4444;
      }
      .welearn-weights-row span.welearn-weights-label {
        color: #cbd5e1;
        white-space: nowrap;
      }
      .welearn-weights-error {
        width: 100%;
        color: #f87171;
        font-size: 10px;
        margin-top: 2px;
        display: none;
      }
      .welearn-weights-error.visible {
        display: block;
      }
      .welearn-duration-row {
        display: flex;
        align-items: center;
        gap: 8px;
        padding: 6px 0 0 0;
        border-top: 1px solid rgba(148, 163, 184, 0.15);
        margin: 4px 0 0 0;
      }
      .welearn-duration-label {
        color: #cbd5e1;
        font-size: 12px;
        white-space: nowrap;
        flex-shrink: 0;
        margin: 0;
        padding: 0;
      }
      .welearn-duration-options {
        display: flex;
        gap: 6px;
        flex: 1;
        min-width: 0;
        margin: 0;
        padding: 0;
      }
      .welearn-duration-btn {
        flex: 1;
        background: rgba(148, 163, 184, 0.15);
        color: #94a3b8;
        border: 1px solid rgba(148, 163, 184, 0.25);
        border-radius: 12px;
        padding: 6px 8px;
        margin: 0;
        font-weight: 600;
        font-size: 11px;
        cursor: pointer;
        box-shadow: none;
        transition: transform 0.12s ease, background 0.2s ease, color 0.2s ease, border-color 0.2s ease, box-shadow 0.2s ease;
        white-space: nowrap;
      }
      .welearn-duration-btn:hover {
        background: rgba(148, 163, 184, 0.25);
        transform: translateY(-1px);
      }
      .welearn-duration-btn.active {
        background: linear-gradient(135deg, #38bdf8, #6366f1);
        background-origin: border-box;
        color: #0b1221;
        border: none;
        box-shadow: 0 4px 10px rgba(99, 102, 241, 0.3);
      }
      .welearn-duration-btn.active:hover {
        transform: translateY(-1px);
        box-shadow: 0 6px 14px rgba(56, 189, 248, 0.32);
      }
      .welearn-handle {
        position: absolute;
        display: none;
      }
      .welearn-minify {
        position: absolute;
        top: 8px;
        right: 10px;
        width: 26px;
        height: 26px;
        border: none;
        border-radius: 50%;
        cursor: pointer;
        background: rgba(56, 189, 248, 0.2);
        color: #38bdf8;
        display: grid;
        place-items: center;
        transition: background 0.15s ease;
        z-index: 10;
      }
      .welearn-minify:hover {
        background: rgba(56, 189, 248, 0.35);
      }
      .welearn-panel.minimized {
        width: ${MINIMIZED_PANEL_SIZE}px !important;
        height: ${MINIMIZED_PANEL_SIZE}px !important;
        min-width: ${MINIMIZED_PANEL_SIZE}px !important;
        max-width: ${MINIMIZED_PANEL_SIZE}px !important;
        padding: 0 !important;
        border-radius: 999px;
      }
      .welearn-panel.minimized h3,
      .welearn-panel.minimized .welearn-footer,
      .welearn-panel.minimized .welearn-handle {
        opacity: 0;
        pointer-events: none;
      }
      .welearn-panel.minimized .welearn-minify {
        top: 50%;
        left: 50%;
        right: auto;
        transform: translate(-50%, -50%);
        width: 26px;
        height: 26px;
      }
      .welearn-panel.minimized .welearn-minify:hover {
        background: rgba(56, 189, 248, 0.4);
      }
      .welearn-toast {
        position: fixed;
        left: 50%;
        transform: translateX(-50%) translateY(-20px);
        padding: 12px 18px;
        background: rgba(16, 185, 129, 0.95);
        color: #0b1221;
        border-radius: 16px;
        box-shadow: 0 12px 28px rgba(16, 185, 129, 0.35);
        font-weight: 600;
        opacity: 0;
        transition: opacity 0.15s ease-out, transform 0.15s ease-out, top 0.2s ease-out;
        z-index: 2147483647;
        font-size: 13px;
        line-height: 1.5;
        will-change: opacity, transform, top;
      }
      .welearn-toast.visible {
        opacity: 1;
        transform: translateX(-50%) translateY(0);
      }
      .welearn-toast .welearn-error-item {
        display: inline-block;
        margin-left: 8px;
        padding: 2px 8px;
        background: rgba(0, 0, 0, 0.15);
        border-radius: 6px;
      }
      .welearn-toast .welearn-error-item b {
        margin-right: 4px;
        font-weight: 600;
      }
      .welearn-toast .welearn-error-item em {
        color: #dc2626;
        font-style: normal;
        font-weight: 700;
      }
      .welearn-modal-overlay {
        position: fixed;
        inset: 0;
        background: rgba(0, 0, 0, 0.45);
        display: flex;
        align-items: center;
        justify-content: center;
        z-index: 2147483647;
        backdrop-filter: blur(4px);
      }
      .welearn-modal {
        width: min(520px, 92vw);
        padding: 20px;
        background: #0f172a;
        color: #e2e8f0;
        border-radius: 20px;
        box-shadow: 0 16px 40px rgba(0, 0, 0, 0.45);
        border: 1px solid rgba(148, 163, 184, 0.2);
        font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
      }
      .welearn-modal h3 {
        margin: 0 0 10px;
        font-size: 18px;
      }
      .welearn-modal p {
        margin: 6px 0;
        line-height: 1.6;
      }
      .welearn-guide {
        margin: 10px 0 14px;
        padding: 10px 12px;
        background: rgba(59, 130, 246, 0.08);
        border-radius: 16px;
        border: 1px solid rgba(59, 130, 246, 0.15);
      }
      .welearn-guide ol {
        margin: 8px 0 0;
        padding-left: 18px;
      }
      .welearn-guide li + li {
        margin-top: 4px;
      }
      .welearn-donate-grid {
        margin: 12px 0 16px;
        display: flex;
        justify-content: center;
      }
      .welearn-donate-grid a {
        display: flex;
        flex-direction: column;
        align-items: center;
        gap: 8px;
        padding: 16px 20px;
        border-radius: 16px;
        background: rgba(148, 163, 184, 0.08);
        border: 1px solid rgba(148, 163, 184, 0.2);
        color: #e2e8f0;
        text-decoration: none;
        box-shadow: inset 0 1px 0 rgba(255, 255, 255, 0.05);
        transition: transform 0.12s ease, border-color 0.12s ease, background 0.12s ease;
      }
      .welearn-donate-grid a:hover {
        transform: translateY(-1px);
        background: rgba(56, 189, 248, 0.08);
        border-color: rgba(56, 189, 248, 0.35);
      }
      .welearn-donate-grid img {
        width: 200px;
        max-width: 100%;
        border-radius: 12px;
        background: #0f172a;
      }
      .welearn-donate-grid span {
        font-weight: 700;
        color: #cbd5e1;
      }
      .welearn-modal-footer {
        display: flex;
        justify-content: space-between;
        align-items: center;
        gap: 10px;
        flex-wrap: wrap;
      }
      .welearn-modal-close {
        background: linear-gradient(135deg, #38bdf8, #22d3ee);
        color: #0b1221;
        border: none;
        border-radius: 16px;
        padding: 10px 16px;
        font-weight: 700;
        cursor: pointer;
        box-shadow: 0 10px 24px rgba(56, 189, 248, 0.35);
        transition: transform 0.12s ease, box-shadow 0.12s ease;
      }
      .welearn-modal-close:hover {
        transform: translateY(-1px);
        box-shadow: 0 12px 26px rgba(56, 189, 248, 0.4);
      }
      .welearn-badge {
        padding: 6px 10px;
        background: rgba(16, 185, 129, 0.16);
        color: #34d399;
        border-radius: 16px;
        border: 1px solid rgba(16, 185, 129, 0.4);
        font-weight: 600;
      }

      /* 批量任务选择器样式 */
      .welearn-task-modal {
        width: min(680px, 92vw);
        max-height: 85vh;
        display: flex;
        flex-direction: column;
      }
      .welearn-task-desc {
        color: #94a3b8;
        margin-bottom: 12px;
      }
      .welearn-task-actions-top {
        display: flex;
        gap: 8px;
        margin-bottom: 12px;
        flex-wrap: wrap;
      }
      .welearn-task-actions-top button {
        background: rgba(148, 163, 184, 0.15);
        color: #94a3b8;
        border: 1px solid rgba(148, 163, 184, 0.25);
        border-radius: 8px;
        padding: 6px 12px;
        font-size: 12px;
        font-weight: 600;
        cursor: pointer;
        transition: all 0.15s ease;
      }
      .welearn-task-actions-top button:hover {
        background: rgba(148, 163, 184, 0.25);
        color: #e2e8f0;
      }
      .welearn-btn-refresh-status {
        background: rgba(16, 185, 129, 0.15) !important;
        color: #34d399 !important;
        border-color: rgba(16, 185, 129, 0.3) !important;
      }
      .welearn-btn-refresh-status:hover {
        background: rgba(16, 185, 129, 0.25) !important;
      }
      .welearn-btn-refresh-status:disabled {
        opacity: 0.6;
        cursor: not-allowed;
      }
      .welearn-task-container {
        flex: 1;
        overflow-y: auto;
        max-height: 50vh;
        margin-bottom: 12px;
        padding-right: 8px;
      }
      .welearn-task-container::-webkit-scrollbar {
        width: 6px;
      }
      .welearn-task-container::-webkit-scrollbar-track {
        background: rgba(148, 163, 184, 0.1);
        border-radius: 3px;
      }
      .welearn-task-container::-webkit-scrollbar-thumb {
        background: rgba(148, 163, 184, 0.3);
        border-radius: 3px;
      }
      .welearn-task-unit {
        margin-bottom: 16px;
      }
      .welearn-task-unit-header {
        background: rgba(56, 189, 248, 0.1);
        border: 1px solid rgba(56, 189, 248, 0.2);
        border-radius: 8px;
        padding: 8px 12px;
        margin-bottom: 8px;
      }
      .welearn-task-unit-header label {
        display: flex;
        align-items: center;
        gap: 8px;
        cursor: pointer;
        font-weight: 600;
        color: #38bdf8;
      }
      .welearn-task-list {
        display: flex;
        flex-direction: column;
        gap: 4px;
        padding-left: 12px;
      }
      .welearn-task-item {
        display: flex;
        align-items: center;
        gap: 8px;
        padding: 8px 12px;
        background: rgba(148, 163, 184, 0.08);
        border-radius: 6px;
        cursor: pointer;
        transition: background 0.15s ease;
      }
      .welearn-task-item:hover {
        background: rgba(148, 163, 184, 0.15);
      }
      .welearn-task-item.completed {
        opacity: 0.6;
        background: rgba(16, 185, 129, 0.1);
      }
      .welearn-task-item.intro {
        opacity: 0.6;
        background: rgba(59, 130, 246, 0.1);
      }
      .welearn-task-item input[type="checkbox"] {
        width: 16px;
        height: 16px;
        cursor: pointer;
      }
      .welearn-task-title {
        flex: 1;
        font-size: 13px;
        color: #e2e8f0;
      }
      .welearn-task-badge {
        font-size: 11px;
        padding: 2px 8px;
        background: rgba(16, 185, 129, 0.2);
        color: #34d399;
        border-radius: 4px;
        font-weight: 600;
      }
      .welearn-task-badge.pending {
        background: rgba(234, 179, 8, 0.2);
        color: #fbbf24;
      }
      .welearn-task-badge.intro {
        background: rgba(59, 130, 246, 0.2);
        color: #60a5fa;
      }
      .welearn-task-summary {
        padding: 10px 12px;
        background: rgba(56, 189, 248, 0.1);
        border-radius: 8px;
        font-size: 13px;
        color: #38bdf8;
        margin-bottom: 12px;
      }
      .welearn-selected-count {
        font-weight: 700;
        font-size: 16px;
      }
      .welearn-checkbox-label {
        display: flex;
        align-items: center;
        gap: 8px;
        cursor: pointer;
      }
      
      /* 加载动画样式 */
      .welearn-loading-container {
        display: flex;
        flex-direction: column;
        align-items: center;
        justify-content: center;
        padding: 60px 20px;
        color: #94a3b8;
      }
      .welearn-loading-spinner {
        width: 40px;
        height: 40px;
        border: 3px solid rgba(56, 189, 248, 0.2);
        border-top-color: #38bdf8;
        border-radius: 50%;
        animation: welearn-spin 0.8s linear infinite;
        margin-bottom: 16px;
      }
      @keyframes welearn-spin {
        to { transform: rotate(360deg); }
      }
      .welearn-loading-container p {
        font-size: 14px;
        margin: 0;
      }
      
      /* 警告文本样式 */
      .welearn-warning-text {
        color: #f87171 !important;
        font-size: 12px;
      }
      
      /* 缓存时间显示 */
      .welearn-cache-time {
        color: #64748b;
        font-size: 11px;
      }
      
      /* 恢复任务提示模态框 */
      .welearn-recovery-modal {
        width: min(400px, 90vw);
        text-align: center;
      }
      .welearn-recovery-modal p {
        margin: 12px 0;
        color: #cbd5e1;
      }
      .welearn-recovery-modal strong {
        color: #38bdf8;
        font-size: 18px;
      }
      
      /* 重新读取按钮特殊样式 */
      .welearn-btn-refresh {
        background: rgba(56, 189, 248, 0.15) !important;
        color: #38bdf8 !important;
        border-color: rgba(56, 189, 248, 0.3) !important;
      }
      .welearn-btn-refresh:hover {
        background: rgba(56, 189, 248, 0.25) !important;
      }
      
      .welearn-modal-cancel {
        background: rgba(148, 163, 184, 0.15);
        color: #94a3b8;
        border: 1px solid rgba(148, 163, 184, 0.25);
        border-radius: 16px;
        padding: 10px 20px;
        font-weight: 600;
        cursor: pointer;
        transition: all 0.15s ease;
      }
      .welearn-modal-cancel:hover {
        background: rgba(148, 163, 184, 0.25);
        color: #e2e8f0;
      }
      .welearn-modal-confirm {
        background: linear-gradient(135deg, #38bdf8, #6366f1);
        color: #fff;
        border: none;
        border-radius: 16px;
        padding: 10px 24px;
        font-weight: 700;
        cursor: pointer;
        box-shadow: 0 8px 18px rgba(99, 102, 241, 0.35);
        transition: all 0.15s ease;
      }
      .welearn-modal-confirm:hover:not(:disabled) {
        transform: translateY(-1px);
        box-shadow: 0 10px 22px rgba(56, 189, 248, 0.32);
      }
      .welearn-modal-confirm:disabled {
        opacity: 0.5;
        cursor: not-allowed;
        transform: none;
        box-shadow: none;
      }
      .welearn-modal-start {
        background: linear-gradient(135deg, #38bdf8, #6366f1);
        color: #0b1221;
        border: none;
        border-radius: 16px;
        padding: 10px 24px;
        font-weight: 700;
        cursor: pointer;
        box-shadow: 0 8px 18px rgba(99, 102, 241, 0.35);
        transition: all 0.15s ease;
      }
      .welearn-modal-start:hover:not(:disabled) {
        transform: translateY(-1px);
        box-shadow: 0 10px 22px rgba(56, 189, 248, 0.32);
      }
      .welearn-modal-start:disabled {
        opacity: 0.5;
        cursor: not-allowed;
      }
      
      /* 读取目录按钮样式 */
      .welearn-scan-btn {
        background: linear-gradient(135deg, #10b981, #059669);
        color: #0b1221;
        border: none;
        border-radius: 16px;
        padding: 10px 12px;
        font-weight: 700;
        font-size: 13px;
        cursor: pointer;
        box-shadow: 0 6px 14px rgba(16, 185, 129, 0.3);
        transition: transform 0.12s ease, box-shadow 0.12s ease, filter 0.12s ease;
      }
      .welearn-scan-btn:hover {
        transform: translateY(-1px);
        box-shadow: 0 8px 18px rgba(16, 185, 129, 0.4);
        filter: brightness(1.03);
      }
      .welearn-scan-btn:disabled {
        opacity: 0.5;
        cursor: not-allowed;
      }
      
      /* 批量执行按钮样式 */
      .welearn-batch-btn {
        background: linear-gradient(135deg, #f59e0b, #ef4444);
        color: #0b1221;
        border: none;
        border-radius: 16px;
        padding: 10px 12px;
        font-weight: 700;
        font-size: 13px;
        cursor: pointer;
        box-shadow: 0 6px 14px rgba(245, 158, 11, 0.3);
        transition: transform 0.12s ease, box-shadow 0.12s ease, filter 0.12s ease;
      }
      .welearn-batch-btn:hover {
        transform: translateY(-1px);
        box-shadow: 0 8px 18px rgba(245, 158, 11, 0.4);
        filter: brightness(1.03);
      }
      .welearn-batch-btn:disabled {
        opacity: 0.5;
        cursor: not-allowed;
      }
      
      /* 批量模式进度提示 */
      .welearn-batch-progress {
        position: fixed;
        bottom: 20px;
        left: 50%;
        transform: translateX(-50%);
        padding: 12px 24px;
        background: rgba(27, 38, 56, 0.95);
        color: #f8fafc;
        border-radius: 16px;
        box-shadow: 0 12px 30px rgba(0, 0, 0, 0.35);
        z-index: 2147483647;
        font-size: 14px;
        font-weight: 600;
        backdrop-filter: blur(6px);
        border: 1px solid rgba(56, 189, 248, 0.3);
      }
      .welearn-batch-progress .progress-text {
        color: #38bdf8;
      }
    `;

    if (typeof GM_addStyle === 'function') {
      GM_addStyle(css);
    } else {
      const style = document.createElement('style');
      style.textContent = css;
      document.head.appendChild(style);
    }
  };

  // ==================== 面板拖动与尺寸控制 ====================

  /** 限制数值在指定范围内 */
  const clampSize = (value, min, max) => Math.min(Math.max(value, min), max);

  /** 获取最大可用宽度 */
  const getMaxWidth = () => Math.min(window.innerWidth - 24, PANEL_MAX_WIDTH);

  /** 获取最大可用高度 */
  const getMaxHeight = () => Math.min(window.innerHeight - 24, PANEL_MAX_HEIGHT);

  /** 获取可见视口尺寸 */
  const getVisibleViewport = () => {
    const vw = window.innerWidth || document.documentElement.clientWidth;
    const vh = window.innerHeight || document.documentElement.clientHeight;
    return { width: vw, height: vh };
  };

  /** 初始化面板拖动和尺寸调整功能 */
  const initDragAndResize = (panel, header) => {
    let startX = 0;
    let startY = 0;
    let startLeft = 0;
    let startTop = 0;
    let isDragging = false;

    const beginInteraction = () => document.body.classList.add('welearn-dragging');
    const endInteraction = () => document.body.classList.remove('welearn-dragging');

    /** 自动调整面板尺寸 */
    const applyAutoSize = () => {
      if (panel.classList.contains('minimized')) {
        panel.style.width = `${MINIMIZED_PANEL_SIZE}px`;
        panel.style.height = `${MINIMIZED_PANEL_SIZE}px`;
        return;
      }

      const { width: vw } = getVisibleViewport();
      const maxW = Math.min(vw - 24, PANEL_MAX_WIDTH);
      const width = clampSize(PANEL_DEFAULT_WIDTH, PANEL_MIN_WIDTH, maxW);
      panel.style.width = `${width}px`;
      panel.style.height = 'auto'; // 高度自适应内容
    };

    /** 确保面板在视口范围内 */
    const enforceBounds = () => {
      const rect = panel.getBoundingClientRect();
      const { width: vw, height: vh } = getVisibleViewport();
      const isMinimized = panel.classList.contains('minimized');
      
      const maxW = Math.min(vw - 24, PANEL_MAX_WIDTH);
      
      const targetWidth = isMinimized
        ? MINIMIZED_PANEL_SIZE
        : clampSize(rect.width, PANEL_MIN_WIDTH, maxW);
      
      // 确保面板完全在视口内
      const minLeft = 8;
      const minTop = 8;
      const maxLeft = Math.max(minLeft, vw - targetWidth - 8);
      const maxTop = Math.max(minTop, vh - rect.height - 8);
      
      panel.style.width = `${targetWidth}px`;
      if (isMinimized) {
        panel.style.height = `${MINIMIZED_PANEL_SIZE}px`;
      }
      panel.style.left = `${clampSize(rect.left, minLeft, maxLeft)}px`;
      panel.style.top = `${clampSize(rect.top, minTop, maxTop)}px`;
    };

    const state = loadPanelState();
    const { width: vw, height: vh } = getVisibleViewport();
    
    // 加载保存的位置,但确保在可见范围内
    if (state.left !== undefined) {
      const maxLeft = Math.max(8, vw - PANEL_DEFAULT_WIDTH - 8);
      panel.style.left = `${clampSize(state.left, 8, maxLeft)}px`;
    }
    if (state.top !== undefined) {
      const maxTop = Math.max(8, vh - PANEL_DEFAULT_HEIGHT - 8);
      panel.style.top = `${clampSize(state.top, 8, maxTop)}px`;
    }
    applyAutoSize();
    if (state.minimized) {
      panel.classList.add('minimized');
      applyAutoSize();
    }
    enforceBounds();

    /** 鼠标移动事件处理(拖动面板) */
    const onMouseMove = (event) => {
      if (isDragging) {
        const { width: vw, height: vh } = getVisibleViewport();
        const rect = panel.getBoundingClientRect();
        const deltaX = event.clientX - startX;
        const deltaY = event.clientY - startY;
        
        const newLeft = startLeft + deltaX;
        const newTop = startTop + deltaY;
        
        // 限制在视口范围内
        const maxLeft = vw - rect.width - 8;
        const maxTop = vh - rect.height - 8;
        
        panel.style.left = `${clampSize(newLeft, 8, maxLeft)}px`;
        panel.style.top = `${clampSize(newTop, 8, maxTop)}px`;
      }
    };

    /** 鼠标释放事件处理(结束拖动并保存状态) */
    const onMouseUp = () => {
      if (isDragging) {
        const rect = panel.getBoundingClientRect();
        const limitedWidth = clampSize(rect.width, PANEL_MIN_WIDTH, getMaxWidth());
        panel.style.width = `${limitedWidth}px`;
        savePanelState({
          left: rect.left,
          top: rect.top,
          width: limitedWidth,
          minimized: panel.classList.contains('minimized'),
        });
      }
      isDragging = false;
      endInteraction();
      document.removeEventListener('mousemove', onMouseMove);
      document.removeEventListener('mouseup', onMouseUp);
    };

    // 展开状态下:只允许通过标题栏拖动
    header.addEventListener('mousedown', (event) => {
      if ((event.target instanceof HTMLElement && event.target.closest('button, input, label')) || panel.classList.contains('minimized')) return;
      event.preventDefault();
      isDragging = true;
      startX = event.clientX;
      startY = event.clientY;
      const rect = panel.getBoundingClientRect();
      startLeft = rect.left;
      startTop = rect.top;
      beginInteraction();
      document.addEventListener('mousemove', onMouseMove);
      document.addEventListener('mouseup', onMouseUp);
    });

    // ==================== 最小化状态拖动处理 ====================
    // 最小化状态使用独立的拖动逻辑,支持拖动移动位置和点击展开
    const DRAG_THRESHOLD = 5;           // 拖动阈值(像素),超过此距离才算拖动,否则视为点击
    
    // 使用对象存储拖动状态,避免闭包问题
    const minDragState = {
      active: false,        // 是否正在拖动
      moved: false,         // 是否已超过阈值
      startX: 0,            // 鼠标起始 X
      startY: 0,            // 鼠标起始 Y
      panelStartX: 0,       // 面板起始 X
      panelStartY: 0,       // 面板起始 Y
      pointerId: null,      // 指针 ID,用于 pointer capture
    };

    /** 结束最小化状态拖动 */
    const endMinimizedDrag = (savePosition = true) => {
      // 释放指针捕获
      if (minDragState.pointerId !== null) {
        try {
          panel.releasePointerCapture(minDragState.pointerId);
        } catch (e) { /* 忽略错误 */ }
        minDragState.pointerId = null;
      }
      
      minDragState.active = false;
      panel.style.cursor = '';
      
      if (minDragState.moved && savePosition) {
        enforceBounds();
        // 延迟重置 moved 状态,确保 click 事件能被正确拦截
        setTimeout(() => {
          minDragState.moved = false;
        }, 50);
      } else {
        minDragState.moved = false;
      }
    };

    /** 最小化状态指针移动处理 */
    const handleMinimizedMove = (event) => {
      if (!minDragState.active) return;
      
      const dx = event.clientX - minDragState.startX;
      const dy = event.clientY - minDragState.startY;
      
      // 检查是否超过拖动阈值
      if (!minDragState.moved && (Math.abs(dx) > DRAG_THRESHOLD || Math.abs(dy) > DRAG_THRESHOLD)) {
        minDragState.moved = true;
        panel.style.cursor = 'grabbing';
      }

      if (minDragState.moved) {
        // 计算新位置并限制在视口范围内
        const { width: vw, height: vh } = getVisibleViewport();
        const newLeft = minDragState.panelStartX + dx;
        const newTop = minDragState.panelStartY + dy;
        const maxLeft = vw - MINIMIZED_PANEL_SIZE - 8;
        const maxTop = vh - MINIMIZED_PANEL_SIZE - 8;
        
        panel.style.left = clampSize(newLeft, 8, maxLeft) + 'px';
        panel.style.top = clampSize(newTop, 8, maxTop) + 'px';
        panel.style.right = 'auto';
        panel.style.bottom = 'auto';
      }
    };

    /** 指针释放处理 */
    const handleMinimizedUp = (event) => {
      if (!minDragState.active) return;
      
      const wasMoved = minDragState.moved;
      endMinimizedDrag();
      
      // 如果没有发生拖动,视为点击,触发展开
      if (!wasMoved && panel.classList.contains('minimized')) {
        // 模拟点击 minify 按钮来展开
        const minifyBtn = panel.querySelector('.welearn-minify');
        if (minifyBtn) {
          minifyBtn.click();
        }
      }
    };

    /** 阻止拖动后的 click 事件 */
    const blockMinimizedClick = (event) => {
      if (minDragState.moved) {
        event.stopPropagation();
        event.preventDefault();
      }
    };

    // 使用 Pointer Events API,支持指针捕获
    panel.addEventListener('pointerdown', (event) => {
      if (!panel.classList.contains('minimized')) return;
      if (event.button !== 0) return; // 只响应左键
      
      const rect = panel.getBoundingClientRect();
      minDragState.active = true;
      minDragState.moved = false;
      minDragState.startX = event.clientX;
      minDragState.startY = event.clientY;
      minDragState.panelStartX = rect.left;
      minDragState.panelStartY = rect.top;
      minDragState.pointerId = event.pointerId;
      
      // 捕获指针,确保即使鼠标快速移动离开元素,事件仍然发送到 panel
      panel.setPointerCapture(event.pointerId);
    });

    panel.addEventListener('pointermove', handleMinimizedMove);
    panel.addEventListener('pointerup', handleMinimizedUp);
    panel.addEventListener('pointercancel', () => endMinimizedDrag(false));
    
    // 当指针捕获丢失时结束拖动
    panel.addEventListener('lostpointercapture', () => {
      if (minDragState.active) {
        endMinimizedDrag();
      }
    });

    // 捕获阶段拦截 click,如果发生了拖动则阻止
    panel.addEventListener('click', blockMinimizedClick, true);

    window.addEventListener('resize', () => {
      applyAutoSize();
      enforceBounds();
    });
  };

  // ==================== 面板初始化 ====================

  /** 初始化控制面板 */
  const initPanel = () => {
    createStyles();
    const panel = document.createElement('div');
    panel.className = 'welearn-panel';
    panel.innerHTML = `
      <div class="welearn-drag-zone"></div>
      <h3>WeLearn-Go<span class="welearn-version">v${VERSION}</span><a class="welearn-update-hint" href="${UPDATE_CHECK_URL}" target="_blank" style="display:none;"></a></h3>
      <button class="welearn-minify" title="折叠">●</button>
      <div class="welearn-body">
        <div class="welearn-actions">
          <button type="button" class="welearn-start">一键填写本页问题</button>
          <button type="button" class="welearn-toggle-btn welearn-submit-toggle">自动提交</button>
          <button type="button" class="welearn-toggle-btn welearn-mistake-toggle">智能添加小错误</button>
          <button type="button" class="welearn-scan-btn">📖 查看目录</button>
          <button type="button" class="welearn-batch-btn">⚡ 批量执行</button>
        </div>
        <div class="welearn-stats-row">
          <span class="welearn-error-stats">错误统计:暂无数据</span>
          <button type="button" class="welearn-clear-stats">清空</button>
        </div>
        <div class="welearn-weights-row">
          <span class="welearn-weights-label">错误比例:</span>
          <label>
            <span class="welearn-weight-text" style="margin:0px!important;">0个</span>
            <input type="text" inputmode="numeric" class="welearn-weight-0" value="50">
            <span class="welearn-weight-text" style="margin:0px!important;">%</span>
          </label>
          <label>
            <span class="welearn-weight-text" style="margin:0px!important;">1个</span>
            <input type="text" inputmode="numeric" class="welearn-weight-1" value="35">
            <span class="welearn-weight-text" style="margin:0px!important;">%</span>
          </label>
          <label>
            <span class="welearn-weight-text" style="margin:0px!important;">2个</span>
            <input type="text" inputmode="numeric" class="welearn-weight-2" value="15">
            <span class="welearn-weight-text" style="margin:0px!important;">%</span>
          </label>
          <span class="welearn-weights-error">总和必须为 100%</span>
        </div>
        <div class="welearn-duration-row">
          <span class="welearn-duration-label">刷时长:</span>
          <div class="welearn-duration-options">
            <button type="button" class="welearn-duration-btn" data-mode="off">⏭️ 关</button>
            <button type="button" class="welearn-duration-btn" data-mode="fast">🚀 快 30-60s</button>
            <button type="button" class="welearn-duration-btn active" data-mode="standard">🐢 慢 60-120s</button>
          </div>
        </div>
        <div class="welearn-footer">
          <span>拖动顶部可移动,点击圆点可折叠</span>
          <a href="https://github.com/noxsk/WeLearn-Go" target="_blank" rel="noopener noreferrer">项目地址</a>
          <button type="button" class="welearn-support">请我喝一杯咖啡 ☕️</button>
        </div>
      </div>
      <div class="welearn-handle"></div>
    `;

    document.body.appendChild(panel);

    // 获取 UI 元素引用
    const header = panel.querySelector('.welearn-drag-zone');
    const startButton = panel.querySelector('.welearn-start');
    const submitToggle = panel.querySelector('.welearn-submit-toggle');
    const mistakeToggle = panel.querySelector('.welearn-mistake-toggle');
    const scanButton = panel.querySelector('.welearn-scan-btn');
    const batchButton = panel.querySelector('.welearn-batch-btn');
    const minifyButton = panel.querySelector('.welearn-minify');
    const supportButton = panel.querySelector('.welearn-support');
    const updateHint = panel.querySelector('.welearn-update-hint');

    // 点击更新提示时的行为
    updateHint?.addEventListener('click', (e) => {
      e.preventDefault();
      showToast(`正在前往 v${latestVersion || '新版本'} 更新页面...(跳转后请稍作等待)`, { duration: 5000 });
      setTimeout(() => {
        window.location.href = UPDATE_CHECK_URL;
      }, 5000);
    });

    // 为按钮添加 checked 属性模拟 checkbox 行为
    submitToggle.checked = false;
    mistakeToggle.checked = false;

    const state = loadPanelState();
    if (state.autoSubmit) {
      submitToggle.checked = true;
      submitToggle.classList.add('active');
    }
    if (state.enableSoftErrors) {
      mistakeToggle.checked = true;
      mistakeToggle.classList.add('active');
    }

    initDragAndResize(panel, header);

    /** 保存当前状态到 localStorage */
    const persistState = () => {
      const rect = panel.getBoundingClientRect();
      if (panel.classList.contains('minimized')) {
        panel.style.width = `${MINIMIZED_PANEL_SIZE}px`;
        panel.style.height = `${MINIMIZED_PANEL_SIZE}px`;
      } else {
        const width = clampSize(PANEL_DEFAULT_WIDTH, PANEL_MIN_WIDTH, getMaxWidth());
        panel.style.width = `${width}px`;
        panel.style.height = 'auto'; // 高度自适应
      }
      savePanelState({
        left: rect.left,
        top: rect.top,
        width: panel.offsetWidth,
        minimized: panel.classList.contains('minimized'),
        autoSubmit: submitToggle.checked,
        enableSoftErrors: mistakeToggle.checked,
      });
    };

    // 绑定事件监听器
    submitToggle.addEventListener('click', () => {
      submitToggle.checked = !submitToggle.checked;
      submitToggle.classList.toggle('active', submitToggle.checked);
      persistState();
    });
    
    mistakeToggle.addEventListener('click', () => {
      mistakeToggle.checked = !mistakeToggle.checked;
      mistakeToggle.classList.toggle('active', mistakeToggle.checked);
      persistState();
    });

    minifyButton.addEventListener('click', () => {
      const wasMinimized = panel.classList.contains('minimized');
      panel.classList.toggle('minimized');
      
      // 展开时检查是否会超出屏幕,如果是则平滑移动到可见区域
      if (wasMinimized) {
        // 等待 CSS 尺寸动画开始后计算实际需要的空间
        requestAnimationFrame(() => {
          const { width: vw, height: vh } = getVisibleViewport();
          const rect = panel.getBoundingClientRect();
          
          // 预估展开后的尺寸
          const expandedWidth = PANEL_DEFAULT_WIDTH;
          const expandedHeight = PANEL_DEFAULT_HEIGHT;
          
          // 计算需要调整的位置
          let targetLeft = rect.left;
          let targetTop = rect.top;
          let needsMove = false;
          
          // 检查右边界
          if (rect.left + expandedWidth > vw - 8) {
            targetLeft = Math.max(8, vw - expandedWidth - 8);
            needsMove = true;
          }
          // 检查下边界
          if (rect.top + expandedHeight > vh - 8) {
            targetTop = Math.max(8, vh - expandedHeight - 8);
            needsMove = true;
          }
          
          if (needsMove) {
            // 添加位置过渡动画
            panel.style.transition = 'width 0.25s ease, height 0.25s ease, min-width 0.25s ease, max-width 0.25s ease, padding 0.25s ease, left 0.25s ease, top 0.25s ease';
            panel.style.left = targetLeft + 'px';
            panel.style.top = targetTop + 'px';
            
            // 动画结束后移除位置过渡,保留原有过渡
            setTimeout(() => {
              panel.style.transition = 'width 0.25s ease, height 0.25s ease, min-width 0.25s ease, max-width 0.25s ease, padding 0.25s ease';
            }, 260);
          }
        });
      }
      
      persistState();
    });

    supportButton?.addEventListener('click', showSupportModal);

    // 读取目录按钮 - 显示任务选择弹窗
    scanButton?.addEventListener('click', () => {
      showTaskSelectorModal();
    });

    // 批量执行按钮 - 执行已选择的任务
    batchButton?.addEventListener('click', () => {
      executeBatchTasks();
    });

    // 清空统计按钮
    const clearStatsButton = panel.querySelector('.welearn-clear-stats');
    clearStatsButton?.addEventListener('click', () => {
      if (confirm('确定要清空错误统计数据吗?')) {
        clearErrorStats();
        showToast('统计数据已清空');
      }
    });

    // 权重设置输入框
    const weight0Input = panel.querySelector('.welearn-weight-0');
    const weight1Input = panel.querySelector('.welearn-weight-1');
    const weight2Input = panel.querySelector('.welearn-weight-2');
    const weightsErrorEl = panel.querySelector('.welearn-weights-error');

    /** 获取输入框的数值,空值返回0 */
    const getInputValue = (input) => {
      const val = input.value.trim();
      if (val === '') return 0;
      const num = parseInt(val, 10);
      return isNaN(num) ? 0 : Math.max(0, Math.min(100, num));
    };

    /** 验证并保存权重配置 */
    const validateAndSaveWeights = () => {
      const w0 = getInputValue(weight0Input);
      const w1 = getInputValue(weight1Input);
      const w2 = getInputValue(weight2Input);
      const total = w0 + w1 + w2;
      
      const isValid = total === 100;
      
      // 显示/隐藏错误提示
      weightsErrorEl.classList.toggle('visible', !isValid);
      [weight0Input, weight1Input, weight2Input].forEach((input) => {
        input.classList.toggle('error', !isValid);
      });
      
      if (isValid) {
        saveErrorWeights({ w0, w1, w2 });
      }
      
      return isValid;
    };

    /** 过滤非数字字符 */
    const filterNonNumeric = (input) => {
      input.value = input.value.replace(/[^0-9]/g, '');
    };

    // 加载已保存的权重配置
    const savedWeights = loadErrorWeights();
    weight0Input.value = savedWeights.w0;
    weight1Input.value = savedWeights.w1;
    weight2Input.value = savedWeights.w2;
    validateAndSaveWeights();

    // 绑定权重输入事件
    [weight0Input, weight1Input, weight2Input].forEach((input) => {
      input.addEventListener('input', () => {
        filterNonNumeric(input);
        validateAndSaveWeights();
      });
      input.addEventListener('change', validateAndSaveWeights);
    });

    // 刷时长模式选择器
    const durationBtns = panel.querySelectorAll('.welearn-duration-btn');
    
    // 加载已保存的刷时长模式
    const savedDurationMode = loadDurationMode();
    durationBtns.forEach((btn) => {
      if (btn.dataset.mode === savedDurationMode) {
        btn.classList.add('active');
      } else {
        btn.classList.remove('active');
      }
    });
    
    // 绑定刷时长模式选择事件
    durationBtns.forEach((btn) => {
      btn.addEventListener('click', () => {
        // 移除所有active
        durationBtns.forEach(b => b.classList.remove('active'));
        // 添加当前active
        btn.classList.add('active');
        
        const mode = btn.dataset.mode;
        saveDurationMode(mode);
        const config = DURATION_MODES[mode];
        if (mode === 'off') {
          showToast('⏭️ 刷时长已关闭,将直接提交', { duration: 2000 });
        } else {
          showToast(`已切换到${config.name}模式:${Math.round(config.baseTime/1000)}-${Math.round(config.maxTime/1000)}秒`, { duration: 2000 });
        }
      });
    });

    // 初始化统计显示
    refreshErrorStatsDisplay();

    // 检查版本更新
    checkForUpdates();

    // 注意:最小化状态下的点击展开逻辑已移至 initDragAndResize 函数中
    // 通过拖动阈值判断:移动小于 5px 视为点击,展开面板

    startButton.addEventListener('click', () => {
      startButton.disabled = true;
      const result = fillAll({ enableSoftErrors: mistakeToggle.checked });
      
      // 同时触发 iframe 内的填充
      triggerIframeFill(mistakeToggle.checked);
      
      if (result.filled) {
        // 更新错误统计(如果启用了添加小错误功能)
        if (mistakeToggle.checked) {
          updateErrorStats(result.errors.length);
        }
        
        // 立即显示填写完成提示
        if (!groupWorkDetected) {
          const errorCount = result.errors.length;
          if (mistakeToggle.checked && errorCount > 0) {
            // 生成带红色高亮的错误详情
            const details = result.errors.map((e) => {
              // 找出不同的字符并标红
              const highlighted = highlightDiff(e.original, e.modified);
              return `<span class="welearn-error-item"><b>${e.type}</b> ${highlighted}</span>`;
            }).join('');
            showToast(`填写完成!已添加 ${errorCount} 处小错误:${details}`, { html: true, duration: 3500 });
          } else if (mistakeToggle.checked) {
            showToast('填写完成!本次无小错误');
          } else {
            showToast('填写完成!');
          }
        }
        
        // 延迟提交(如果启用)
        if (submitToggle.checked) {
          setTimeout(() => {
            submitIfNeeded(true);
            startButton.disabled = false;
          }, SUBMIT_DELAY_MS);
        } else {
          startButton.disabled = false;
        }
      } else {
        // 检查是否有 iframe 可能包含内容
        const hasIframes = document.querySelectorAll('iframe').length > 0;
        if (hasIframes) {
          showToast('已发送填充请求到页面框架');
        } else {
          showToast('未发现可填写的内容');
        }
        startButton.disabled = false;
      }
    });
  };

  /** 确保面板已挂载到页面 */
  const ensurePanelMounted = () => {
    if (!document.body) return;
    if (document.querySelector('.welearn-panel')) return;
    initPanel();
  };

  // ==================== 引导模态框 ====================

  /** 加载引导状态 */
  const loadOnboardingState = () => {
    try {
      const raw = localStorage.getItem(ONBOARDING_STATE_KEY);
      return raw ? JSON.parse(raw) : {};
    } catch (error) {
      console.warn('WeLearn autofill: failed to load onboarding state', error);
      return {};
    }
  };

  /** 保存引导状态 */
  const saveOnboardingState = (state) => {
    try {
      localStorage.setItem(ONBOARDING_STATE_KEY, JSON.stringify(state));
    } catch (error) {
      console.warn('WeLearn autofill: failed to save onboarding state', error);
    }
  };

  // ==================== 赞赏码图片缓存 ====================

  /** 从 localStorage 加载缓存的图片 */
  const loadCachedDonateImage = () => {
    try {
      const cached = localStorage.getItem(DONATE_IMAGE_CACHE_KEY);
      if (cached) {
        donateImageDataUrl = cached;
        return true;
      }
    } catch (error) {
      console.warn('WeLearn: 加载缓存图片失败', error);
    }
    return false;
  };

  /** 预加载赞赏码图片(仅预热浏览器缓存,不转换为 Data URL) */
  const preloadDonateImage = () => {
    // 如果已有缓存,直接使用
    if (loadCachedDonateImage()) {
      console.info('[WeLearn-Go] 已从缓存加载赞赏码图片');
      return;
    }

    // 使用 Image 对象预加载图片(不设置 crossOrigin,避免 CORS 问题)
    // 这样图片会被浏览器缓存,后续显示时可以直接从缓存加载
    const img = new Image();
    img.onload = () => {
      console.info('[WeLearn-Go] 赞赏码图片已预加载到浏览器缓存');
    };
    // 静默处理错误,不影响脚本运行
    img.onerror = () => {};
    img.src = DONATE_IMAGE_URL;
  };

  /** 显示赞赏模态框 */
  const showSupportModal = () => {
    // 使用缓存的图片或原始 URL
    const imageUrl = donateImageDataUrl || DONATE_IMAGE_URL;
    const overlay = document.createElement('div');
    overlay.className = 'welearn-modal-overlay';
    overlay.innerHTML = `
      <div class="welearn-modal">
        <h3>赞助支持</h3>
        <p>如果你能请我喝一杯咖啡,我将不胜感激!</p>
        <div class="welearn-donate-grid">
          <a href="${DONATE_IMAGE_URL}" target="_blank" rel="noopener noreferrer">
            <img src="${imageUrl}" alt="微信赞赏码">
            <span>微信</span>
          </a>
        </div>
        <div class="welearn-modal-footer">
          <span class="welearn-badge">感谢支持</span>
          <button type="button" class="welearn-modal-close">关闭</button>
        </div>
      </div>
    `;

    const close = () => overlay.remove();
    overlay.addEventListener('click', (event) => {
      if (event.target === overlay) close();
    });

    overlay.querySelector('.welearn-modal-close')?.addEventListener('click', close);

    document.body.appendChild(overlay);
  };

  /** 显示首次使用引导模态框 */
  const showOnboardingModal = () => {
    const state = loadOnboardingState();
    if (state.seen) return;

    const overlay = document.createElement('div');
    overlay.className = 'welearn-modal-overlay';
    overlay.innerHTML = `
      <div class="welearn-modal">
        <h3>使用须知</h3>
        <p>本脚本仅供学习使用,请在 24H 内删除。对使用该脚本产生的后果均由使用者承担。</p>
        <p>本脚本始终保持免费,如购买所得说明被骗了。</p>
        <div class="welearn-guide">
          <p>简易使用教程:</p>
          <ol>
            <li>进入对应课程练习页面(当前已适配:领航大学英语综合教程1)。</li>
            <li>点击页面左侧的「一键填写」按钮自动填写答案。</li>
            <li>如需自动提交,可在面板中勾选「自动提交」。</li>
          </ol>
        </div>
        <div class="welearn-modal-footer">
          <span class="welearn-badge">适配:领航大学英语综合教程1</span>
          <button type="button" class="welearn-modal-close">我已知晓</button>
        </div>
      </div>
    `;

    const close = () => {
      saveOnboardingState({ seen: true });
      overlay.remove();
    };

    overlay.addEventListener('click', (event) => {
      if (event.target === overlay) close();
    });

    const closeButton = overlay.querySelector('.welearn-modal-close');
    closeButton?.addEventListener('click', close);

    document.body.appendChild(overlay);
  };

  // ==================== 页面生命周期管理 ====================

  /** 初始化页面元素 */
  const initPageArtifacts = (showSwitchToast = false) => {
    groupWorkDetected = false;
    groupWorkNoticeShown = false;
    openEndedExerciseShown = false;
    cleanupPageArtifacts();
    showOnboardingModal();
    ensurePanelMounted();
    if (!ensurePanelMounted.observer && document.body) {
      ensurePanelMounted.observer = new MutationObserver(() => ensurePanelMounted());
      ensurePanelMounted.observer.observe(document.body, { childList: true, subtree: true });
    }
    if (showSwitchToast && !isInIframe()) {
      showToast('检测到页面切换,已为新作业自动初始化');
    }
    
    // 检查批量任务状态
    setTimeout(() => {
      // 检查是否有正在进行的批量执行
      const batchState = loadBatchModeState();
      const isExecuting = batchState && batchState.active;
      
      if (isOnCourseDirectoryPage()) {
        // 在目录页面
        if (isExecuting && batchState.phase === 'returning') {
          // 批量执行中,从任务页面返回,继续执行下一个任务
          console.log('[WeLearn-Go] 批量执行: 已返回目录页面,继续执行下一个任务');
          batchModeActive = true;
          showBatchProgressIndicator(batchState.totalTasks, batchState.currentIndex);
          
          setTimeout(() => {
            executeNextTask();
          }, 1500);
        } else if (!batchModeActive && !isExecuting && selectedBatchTasks.length === 0) {
          // 没有正在执行的批量任务,检查异常中断的任务
          checkAndResumeBatchMode();
          
          // 检查是否有缓存的任务可以恢复
          const tasksCache = loadBatchTasksCache();
          if (tasksCache && tasksCache.tasks && tasksCache.tasks.length > 0) {
            showBatchTasksRecoveryPrompt();
          }
        }
      } else if (isExecuting) {
        // 在任务页面,且批量执行正在进行中
        // 支持多种 phase:navigating(正在导航到任务)、filling(填写中被刷新)、submitting(提交中被刷新)
        const shouldFill = ['navigating', 'filling', 'submitting'].includes(batchState.phase);
        
        if (shouldFill) {
          console.log('[WeLearn-Go] 批量执行: 任务页面已加载,开始填写 (phase:', batchState.phase + ')');
          batchModeActive = true;
          showBatchProgressIndicator(batchState.totalTasks, batchState.currentIndex);
          
          // 等待页面完全加载后执行填写(增加延迟到 3 秒)
          setTimeout(() => {
            executeFillAndSubmit();
          }, 3000);
        } else {
          console.log('[WeLearn-Go] 批量执行: 未知 phase,跳过当前任务', batchState.phase);
          // 跳过当前任务,继续下一个
          skipCurrentTask('页面状态异常');
        }
      }
    }, 1500);
  };

  /** 在 iframe 中初始化(不显示面板,监听父窗口消息) */
  const initInIframe = () => {
    console.info('[WeLearn-Go]', 'iframe 模式已加载', location.href);
    
    // 使用 MutationObserver 监听 DOM 变化,适应 SPA
    const observer = new MutationObserver((mutations) => {
       // 简单的防抖,避免频繁检测
       if (observer.timer) clearTimeout(observer.timer);
       observer.timer = setTimeout(() => {
         checkContent();
       }, 1000);
    });
    
    observer.observe(document.body, { childList: true, subtree: true });
    
    // 检测页面是否有练习元素
    const checkContent = () => {
      const blanks = document.querySelectorAll('et-blank');
      const toggles = document.querySelectorAll('et-toggle');
      const items = document.querySelectorAll('et-item');
      const allContentEditable = document.querySelectorAll('[contenteditable="true"]');
      console.info('[WeLearn-Go] iframe 内容检测:', {
        'et-blank': blanks.length,
        'et-toggle': toggles.length,
        'et-item': items.length,
        'contenteditable': allContentEditable.length
      });
    };
    
    // 监听来自父窗口的填充请求
    window.addEventListener('message', (event) => {
      // 验证消息来源
      if (!event.origin.includes('sflep.com')) return;
      
      if (event.data?.type === 'welearn-fill') {
        const result = fillAll({ enableSoftErrors: event.data.enableSoftErrors || false });
        // 向父窗口报告结果
        try {
          window.parent.postMessage({
            type: 'welearn-fill-result',
            ...result
          }, '*');
        } catch (e) { /* 忽略跨域错误 */ }
      }
    });
    
    // 暴露全局 API 供父窗口或控制台调用
    window.WeLearnGo = {
      fill: (options = {}) => fillAll(options),
      isReady: true
    };
    
    // 通知父窗口 iframe 已准备就绪
    try {
      window.parent.postMessage({ type: 'welearn-iframe-ready' }, '*');
    } catch (e) { /* 忽略跨域错误 */ }
  };

  /** 脚本入口函数 */
  const start = () => {
    if (!isWeLearnHost()) return;
    console.info('[WeLearn-Go]', '辅助脚本已加载,祝你学习顺利!','相关内容仅供学习研究,请在 24H 内删除。','使用该脚本产生的后果均由使用者承担。');
    
    const run = () => {
      if (!document.body) {
        setTimeout(run, 50);
        return;
      }
      
      // 根据是否在 iframe 中采用不同策略
      if (isInIframe()) {
        initInIframe();
        // iframe 中也需要自动确认
        startAutoConfirmDialog();
      } else {
        // 预加载赞赏码图片(只在主页面)
        preloadDonateImage();
        initPageArtifacts();
        monitorPageSwitches();
        // 监听 iframe 就绪消息
        listenForIframeReady();
        // 启动自动确认提交对话框监听
        startAutoConfirmDialog();
      }
    };

    run();
  };

  /** 监听 iframe 就绪消息,并触发填充 */
  const listenForIframeReady = () => {
    window.addEventListener('message', (event) => {
      if (!event.origin.includes('sflep.com')) return;
      
      if (event.data?.type === 'welearn-iframe-ready') {
        console.info('[WeLearn-Go]', 'iframe 已就绪');
      }
      
      if (event.data?.type === 'welearn-fill-result') {
        // 收到 iframe 填充结果
        if (event.data.filled) {
          console.info('[WeLearn-Go]', 'iframe 填充完成');
        }
      }
    });
  };

  /** 触发 iframe 中的填充操作 */
  const triggerIframeFill = (enableSoftErrors = false) => {
    const iframes = document.querySelectorAll('iframe');
    iframes.forEach((iframe) => {
      try {
        iframe.contentWindow?.postMessage({
          type: 'welearn-fill',
          enableSoftErrors
        }, '*');
      } catch (e) { /* 忽略跨域错误 */ }
    });
  };

  /** 处理页面切换(重新初始化) */
  const handlePageChange = () => {
    if (!isWeLearnHost()) return;
    initPageArtifacts(true);
  };

  /** 监控页面切换(SPA 路由变化) */
  const monitorPageSwitches = () => {
    const WATCH_INTERVAL_MS = 1000;
    if (monitorPageSwitches.started) return;
    monitorPageSwitches.started = true;

    setInterval(() => {
      if (location.href === lastKnownUrl) return;
      lastKnownUrl = location.href;
      handlePageChange();
    }, WATCH_INTERVAL_MS);
  };

  // ==================== 脚本启动 ====================

  if (document.readyState === 'loading') {
    document.addEventListener('DOMContentLoaded', start, { once: true });
  } else {
    start();
  }
})();