Chrome MV3 插件实战：模拟真人自动评论的架构设计与三个真实踩坑

┌──────────────────────────────────────────────┐
│ sidepanel.js/html  （用户界面层）             │
│  配置、进度、日志、授权横幅、统计              │
└──────────────┬───────────────────────────────┘
               │ chrome.runtime.sendMessage
┌──────────────▼───────────────────────────────┐
│ background.js      （任务调度层 SW）           │
│  授权校验、找B站标签页、下发任务、持有任务副本  │
└──────────────┬───────────────────────────────┘
               │ chrome.tabs.sendMessage
┌──────────────▼───────────────────────────────┐
│ content.js         （执行层，注入视频页）      │
│  搜索→筛选→打开→滚动→输入→发布→等待           │
└──────────────────────────────────────────────┘

if (msg.action === "pullTask") {
  if (ACTIVE_TASK && Date.now() - (ACTIVE_TASK.ts || 0) <= 120000) {
    sendResponse({ task: ACTIVE_TASK });
  } else {
    ACTIVE_TASK = null;
    sendResponse({ task: null });
  }
}

// 逐字输入，每字间隔 40~120ms 随机
async function typeText(el, text) {
  el.focus();
  for (const ch of text) {
    el.value += ch;
    el.dispatchEvent(new Event("input", { bubbles: true }));
    await sleep(40 + Math.random() * 80);
  }
}

async function stopRequested() {
  const st = await chrome.storage.local.get("stopFlag");
  return !!st.stopFlag;
}
// 在真正发送前必须再查一次
if (await stopRequested()) { finish(task, false, "已手动停止"); return; }

const STOP_CODES = {
  "12045": "触发验证码风控，已停止，请稍后再试",
  "12002": "评论频率过快，已停止，请加大间隔",
  "12008": "今日评论已达上限，明天再来",
  "12010": "账号异常需验证手机",
  "-101":  "账号未登录或登录已过期",
};

const chunks = [];
const res = await fetch(url, { headers: { Referer: location.href } });
const reader = res.body.getReader();
while (true) {
  const { done, value } = await reader.read();
  if (done) break;
  chunks.push(value);
}
const blob = new Blob(chunks);           // ← 这里出事了

const resp = await fetch(url, { headers: { Referer: location.href } });
if (!resp.ok) throw new Error("HTTP " + resp.status);
const ct = resp.headers.get("content-type") || "";
if (ct.includes("text/html")) throw new Error("CDN 返回的不是视频，是网页/错误页");

const buf = await resp.arrayBuffer();
const head = new Uint8Array(buf.slice(0, 16));

// 魔数校验：mp4 ftyp、flv、mp3 ID3、webm EBML
const MAGIC = {
  "video/mp4":  [0x66, 0x74, 0x79, 0x70],           // ftyp @4
  "video/x-flv": [0x46, 0x4C, 0x56],                 // FLV
  "audio/aac":  [0x49, 0x44, 0x33],                  // ID3
  "video/webm": [0x1A, 0x45, 0xDF, 0xA3],            // EBML
};
function sniff(head) {
  if (String.fromCharCode(...head.slice(4, 8)) === "ftyp") return "video/mp4";
  if (head[0] === 0x46 && head[1] === 0x4C) return "video/x-flv";
  if (head[0] === 0x49 && head[1] === 0x44) return "audio/aac";
  if (head[0] === 0x1A && head[1] === 0x45) return "video/webm";
  return null;
}
const mime = sniff(head) || ct;
if (!mime.startsWith("video/") && !mime.startsWith("audio/")) {
  throw new Error("CDN 返回的不是视频（是网页/错误页），已拦截");
}

const blob = new Blob([buf], { type: mime });   // ← 必须带 type

const fresh = await ensureFreshContent(tab.id);
if (!fresh) {
  sendResponse({ ok: false, error: "B站页面脚本未就绪，请手动刷新该标签页后重试" });
  return;
}

let authorized = false, offline = false;
try {
  const r = await authFetch("/public/authorizations/query?bot_qq=" + machine);
  if (r && r.code === 200 && Array.isArray(r.data?.list)) {
    authorized = r.data.list.some(it =>
      it.project_name === PROJECT_NAME && it.status === "active" && !it.is_expired);
  }
} catch (e) {
  offline = true;   // 网络/超时 → 视为放行
}

return {
  authorized: authorized || offline,
  offline: offline,
  realAuthorized: authorized,
};

function verifyMessage(text) {
  const t = String(text || "").trim();
  if (t.length < 3)   return { ok: false, reason: "至少3个字" };
  if (t.length > 200) return { ok: false, reason: "最多200字" };
  if (/https?:\/\/|www\./i.test(t)) return { ok: false, reason: "不能含外链" };
  // 重复字检测：按长度自适应阈值
  const uniq = new Set(t.replace(/\s/g, "")).size;
  const threshold = Math.max(2, Math.floor(t.length * 0.3));
  if (uniq < threshold) return { ok: false, reason: "内容重复度过高" };
  return { ok: true, text: t };
}