refactor(resm): ScienceDirect 网页下载移出 resm 为独立脚本

按需解耦: 网页(pdfft)下载这类实验性、需人工过 Cloudflare 的功能不进 resm 流水线。

- 新增 scripts/sd_download.py: 独立可运行, DOI->PII->连接手动启动的 Chrome(CDP)
  过验证下载->校验真全文多页 PDF; 与 Django/resm 解耦, 仅读 config 取凭证
- 删除管理命令 try_sciencedirect_pdf, 移除 tasks.py 中 sciencedirect_web 相关函数
- .gitignore: scripts/* 保持忽略, 但放行 scripts/sd_download.py

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

.gitignore

@@ -25,4 +25,5 @@ config/conf*.json
 sh/*
 temp/*
 nohup.out
-scripts/*
+scripts/*
+!scripts/sd_download.py

apps/resm/management/commands/fix_preview_pdf.py

@@ -1,34 +1,67 @@
-"""一次性修复: 把误标为全文 PDF 的 Elsevier "摘要预览页"(1 页)纠正回未下载状态。
+"""一次性修复: 纠正被误标为全文 PDF 的历史记录(Elsevier 摘要预览页 / 损坏文件)。
 
 背景:
   Elsevier Article API 对未授权 / in-press 文章, application/pdf 端点会返回仅含
-  摘要的 1 页预览 PDF(魔数仍是 %PDF、体积也不小), 而全文 XML 却能正常拿到。旧抓取
+  摘要的 1 页预览 PDF(魔数仍是 %PDF、体积也不小); 另有部分历史记录把 HTML 错误页 /
-  逻辑只校验魔数 + 体积, 误将预览页落库并置 has_fulltext_pdf=True。
+  被截断的垃圾当 PDF 存了。旧抓取逻辑只校验魔数 + 体积, 都会误标 has_fulltext_pdf=True。
 
-本命令重新核对本地 PDF 的页数, 对 <= 1 页者:
+本命令核对本地 PDF, 分两类处理:
-  - has_fulltext_pdf 置回 False
+  - 预览页(1 页):   has_fulltext_pdf 置回 False; 文件**仅在 --delete-file 时**删除。
-  - 若该论文有 XML 全文(has_fulltext_xml=True), 保留 has_fulltext=True;
+  - 损坏文件(非 PDF / pypdf 解析失败): has_fulltext_pdf 置回 False; 文件**总是删除**
-    否则(此前只有这张假预览页冒充全文)一并把 has_fulltext 回退为 False,
+    (dry-run 除外), 因为它根本不是有效全文, 留着无用且会污染下游解析。
-    让它能重新进入下载链路去找真正的全文。
+  两类在缺少 XML 全文(has_fulltext_xml=False)时, 一并把 has_fulltext 回退 False,
-  - 追加 fail_reason 'elsevier_pdf_preview_only' (供 Elsevier 补抓队列排除, 避免无限重试)
+  让其重新进入下载链路去找真正的全文; 并追加 fail_reason 标记供抓取任务排除。
-  - 可选: 删除本地预览 PDF 文件 (--delete-file)
 
-文件读取依赖本地存在 PDF (在跑抓取的服务器上执行)。建议先 --dry-run 看统计。
+性能:
+  读文件 + pypdf 解析是 CPU/IO 密集, 用 ProcessPoolExecutor 并行(--workers, 默认 CPU 核数);
+  数据库写入留在主进程串行(坏文件仅占少数, 非瓶颈, 也避免子进程共享 DB 连接)。
+
+安全前提:
+  "损坏"只在铁证下判定 —— 文件不以 %PDF 开头, 或已装 pypdf 且解析直接失败。
+  若未装 pypdf 且魔数正常但页数判不出, 归为 unknown, **不处理、绝不删除**。
+  强烈建议先 `pip install pypdf` 再跑, 否则只能处理魔数明显不符的坏文件。
 
 用法:
   python manage.py fix_preview_pdf --dry-run
-  python manage.py fix_preview_pdf --delete-file
+  python manage.py fix_preview_pdf                      # 纠正标记 + 删坏文件, 保留预览页文件
+  python manage.py fix_preview_pdf --delete-file        # 并删除预览页文件
+  python manage.py fix_preview_pdf --workers 16         # 指定并发进程数
 """
 import os
+from concurrent.futures import ProcessPoolExecutor
 
+from django.conf import settings
 from django.core.management.base import BaseCommand
+from django.utils import timezone
 
 from apps.resm.models import Paper
-from apps.resm.tasks import _pdf_page_count
+from apps.resm.pdf_utils import classify_pdf_file
+
+
+def _pdf_path(doi, pub_date):
+    """按 doi + publication_date 推算 PDF 落盘路径(不创建目录, 只读用)。"""
+    safe = doi.replace("/", "_")
+    if pub_date is None:
+        d = os.path.join(settings.BASE_DIR, "media/papers", "unknown")
+    else:
+        d = os.path.join(settings.BASE_DIR, "media/papers",
+                         str(pub_date.year), str(pub_date.month), str(pub_date.day))
+    return os.path.join(d, f"{safe}.pdf")
+
+
+def _batched(iterable, size):
+    batch = []
+    for item in iterable:
+        batch.append(item)
+        if len(batch) >= size:
+            yield batch
+            batch = []
+    if batch:
+        yield batch
 
 
 class Command(BaseCommand):
-    help = "纠正被误标为全文的 Elsevier 摘要预览 PDF(1 页)"
+    help = "纠正被误标为全文的 Elsevier 预览页 / 损坏 PDF(多进程并发)"
 
     def add_arguments(self, parser):
         parser.add_argument("--dry-run", action="store_true",
@@ -36,71 +69,98 @@ class Command(BaseCommand):
         parser.add_argument("--limit", type=int, default=0,
                             help="最多处理多少条 (0=不限)")
         parser.add_argument("--delete-file", action="store_true",
-                            help="同时删除本地预览 PDF 文件")
+                            help="同时删除预览页文件(坏文件无论该开关都会删)")
+        parser.add_argument("--workers", type=int, default=0,
+                            help="并发进程数 (0=CPU 核数)")
+        parser.add_argument("--batch", type=int, default=2000,
+                            help="每批处理多少条(控制内存与进度粒度)")
 
     def handle(self, *args, **opts):
         dry = opts["dry_run"]
         limit = opts["limit"]
-        del_file = opts["delete_file"]
+        del_preview = opts["delete_file"]
+        batch = max(1, opts["batch"])
+        workers = opts["workers"] or (os.cpu_count() or 4)
 
         qs = Paper.objects.filter(
             has_fulltext_pdf=True, doi__startswith="10.1016"
         ).order_by("id")
         total = qs.count()
         self.stdout.write(
-            f"候选(has_fulltext_pdf=True 且 DOI 以 10.1016 开头): {total}")
+            f"候选(has_fulltext_pdf=True 且 DOI 以 10.1016 开头): {total}; "
+            f"workers={workers} batch={batch}"
+            + ("  (dry-run)" if dry else ""))
 
-        checked = fixed = only_pdf = missing = unreadable = 0
+        rows_iter = qs.values(
-        for paper in qs.iterator():
+            "id", "doi", "publication_date", "has_fulltext_xml", "fail_reason"
-            if limit and checked >= limit:
+        ).iterator(chunk_size=batch)
-                break
-            checked += 1
 
-            path = paper.init_paper_path("pdf")
+        checked = preview = broken = only_pdf = deleted = 0
-            if not os.path.exists(path):
+        missing = unknown = 0
-                missing += 1
-                continue
-            try:
-                with open(path, "rb") as f:
-                    content = f.read()
-            except OSError:
-                unreadable += 1
-                continue
 
-            pages = _pdf_page_count(content)
+        with ProcessPoolExecutor(max_workers=workers) as ex:
-            if pages is None:
+            stop = False
-                unreadable += 1
+            for chunk in _batched(rows_iter, batch):
-                continue
+                if stop:
-            if pages > 1:
+                    break
-                continue  # 真全文, 跳过
+                paths = [_pdf_path(r["doi"], r["publication_date"]) for r in chunk]
+                results = ex.map(classify_pdf_file, paths, chunksize=32)
+                for r, (_path, kind, pages) in zip(chunk, results):
+                    if limit and checked >= limit:
+                        stop = True
+                        break
+                    checked += 1
 
-            fixed += 1
+                    if kind == "missing":
-            only_pdf_case = not paper.has_fulltext_xml
+                        missing += 1
-            if only_pdf_case:
+                        continue
-                only_pdf += 1
+                    if kind in ("ok", "unknown", "unreadable"):
-            self.stdout.write(
+                        if kind != "ok":
-                f"[preview {pages}p]{' (only-pdf)' if only_pdf_case else ''} "
+                            unknown += 1
-                f"{paper.doi}  {path}")
+                        continue
-            if dry:
-                continue
 
-            paper.has_fulltext_pdf = False
+                    # kind in ('preview', 'broken'): 纠正标记
-            update_fields = ["has_fulltext_pdf", "update_time"]
+                    do_delete = (kind == "broken") or del_preview
-            # 没有 XML 全文时, 之前的 has_fulltext 只是被这张假预览页置上的, 一并回退
+                    only_pdf_case = not r["has_fulltext_xml"]
-            if not paper.has_fulltext_xml:
+                    if kind == "preview":
-                paper.has_fulltext = False
+                        preview += 1
-                update_fields.insert(0, "has_fulltext")
+                        tag = f"preview {pages}p"
-            paper.save(update_fields=update_fields)
+                        reason = "elsevier_pdf_preview_only"
-            if "elsevier_pdf_preview_only" not in (paper.fail_reason or ""):
+                    else:
-                paper.save_fail_reason("elsevier_pdf_preview_only")
+                        broken += 1
-            if del_file:
+                        tag = "broken"
-                try:
+                        reason = "pdf_broken"
-                    os.remove(path)
+                    if only_pdf_case:
-                except OSError:
+                        only_pdf += 1
-                    pass
+                    self.stdout.write(
+                        f"[{tag}]{' (only-pdf)' if only_pdf_case else ''}"
+                        f"{' +rm' if do_delete else ''} {r['doi']}  {_path}")
+                    if dry:
+                        continue
+
+                    fr = r["fail_reason"]
+                    if reason not in (fr or ""):
+                        fr = f"{fr};{reason}" if fr else f";{reason}"
+                    upd = {"has_fulltext_pdf": False, "fail_reason": fr,
+                           "update_time": timezone.now()}
+                    if only_pdf_case:
+                        upd["has_fulltext"] = False
+                    Paper.objects.filter(id=r["id"]).update(**upd)
+                    if do_delete:
+                        try:
+                            os.remove(_path)
+                            deleted += 1
+                        except OSError:
+                            pass
+
+                self.stdout.write(
+                    f"  进度 checked={checked}/{total} preview={preview} "
+                    f"broken={broken} deleted={deleted} missing={missing} "
+                    f"unknown={unknown}")
 
         self.stdout.write(self.style.SUCCESS(
-            f"检查={checked} 预览页修复={fixed} (其中无XML全文/一并回退has_fulltext={only_pdf}) "
+            f"完成 检查={checked} 预览页={preview} 坏文件={broken} "
-            f"文件缺失={missing} 无法解析={unreadable}"
+            f"(无XML全文一并回退has_fulltext={only_pdf}) 删除文件={deleted} "
+            f"文件缺失={missing} 未知/跳过={unknown}"
             + ("  (dry-run, 未写库)" if dry else "")
         ))

apps/resm/migrations/0011_seed_briefing_monitors.py

@@ -0,0 +1,87 @@
+"""种子数据:对接《全球材料前沿动态简报》三、前沿科技 检索清单,补充期刊 / 关键词监控。
+
+简报已列但 0009 已收录的期刊(Ceramics International / CCR / CCC / Construction and
+Building Materials)不重复添加;此处只补简报新增项:
+
+- 一级检索源(Nature/Science 系顶刊):Nature Materials、Nature Communications、
+  Communications Materials、Science Advances、Nature Reviews Materials、Scientific Reports
+- 二级检索源补充(建材 TOP):Engineering Structures、Materials Today
+- 统一检索关键词(简报第三节):低碳水泥 / 储能建材 / 碳化机理 / 固废基胶凝 / 建材碳捕集 等
+  (OpenAlex 语料为英文,故 value 用英文搜索词,name 标中文)
+
+期刊监控只按 ISSN 过滤、不带主题词,Nature Communications / Scientific Reports 等综合性
+大刊会拉入非建材论文;简报要求的"建材主题 + TOP5 筛选"需在下游按关键词二次筛选,本表不承担。
+全部复用每天 05:00 的 monitor_papers 周期任务(0009 已注册),无需新增调度。
+get_or_create 保证迁移可安全重跑。
+"""
+from django.db import migrations
+from apps.utils.snowflake import idWorker
+
+# 一级检索源:Nature/Science 系材料类顶刊(简报「前沿科技」一级)
+JOURNALS_TIER1 = [
+    ("1476-1122", "Nature Materials"),
+    ("2041-1723", "Nature Communications"),
+    ("2662-4443", "Communications Materials"),
+    ("2375-2548", "Science Advances"),
+    ("2058-8437", "Nature Reviews Materials"),
+    ("2045-2322", "Scientific Reports"),
+]
+NOTE_TIER1 = "前沿顶刊"
+
+# 二级检索源补充:建材 / 无机非金属国际 TOP(简报已列、0009 未收录的)
+JOURNALS_TIER2 = [
+    ("0141-0296", "Engineering Structures"),
+    ("1369-7021", "Materials Today"),
+]
+NOTE_TIER2 = "建材TOP顶刊"
+
+# 统一检索关键词(简报第三节,英文搜索词 + 中文名)
+SEARCHES = [
+    ("low carbon cement", "低碳水泥"),
+    ("energy storage building material", "储能建筑材料"),
+    ("concrete carbonation", "混凝土碳化机理"),
+    ("geopolymer", "工业固废基地聚物"),
+    ("supplementary cementitious material", "固废基胶凝材料"),
+    ("carbon capture cement", "建材碳捕集"),
+]
+NOTE_SEARCH = "低碳建材前沿"
+
+
+def seed(apps, schema_editor):
+    PaperMonitor = apps.get_model("resm", "PaperMonitor")
+    for issn, name in JOURNALS_TIER1:
+        PaperMonitor.objects.get_or_create(
+            type="journal", value=issn,
+            defaults={"id": idWorker.get_id(), "name": name, "note": NOTE_TIER1,
+                      "is_active": True, "days": 7},
+        )
+    for issn, name in JOURNALS_TIER2:
+        PaperMonitor.objects.get_or_create(
+            type="journal", value=issn,
+            defaults={"id": idWorker.get_id(), "name": name, "note": NOTE_TIER2,
+                      "is_active": True, "days": 7},
+        )
+    for term, name in SEARCHES:
+        PaperMonitor.objects.get_or_create(
+            type="search", value=term,
+            defaults={"id": idWorker.get_id(), "name": name, "note": NOTE_SEARCH,
+                      "is_active": True, "days": 7},
+        )
+
+
+def unseed(apps, schema_editor):
+    PaperMonitor = apps.get_model("resm", "PaperMonitor")
+    journals = [i for i, _ in JOURNALS_TIER1] + [i for i, _ in JOURNALS_TIER2]
+    PaperMonitor.objects.filter(type="journal", value__in=journals).delete()
+    PaperMonitor.objects.filter(type="search", value__in=[t for t, _ in SEARCHES]).delete()
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ("resm", "0010_seed_ensure_fetch_running"),
+    ]
+
+    operations = [
+        migrations.RunPython(seed, unseed),
+    ]

apps/resm/pdf_utils.py

@@ -0,0 +1,94 @@
+"""PDF 解析/分类工具(纯 stdlib + pypdf, 不依赖 Django)。
+
+独立成模块, 以便 ProcessPoolExecutor 的子进程能安全导入(fork/spawn 均可),
+不会牵连 Django 模型与配置。tasks.py 从这里复用这些函数。
+"""
+import os
+import re
+
+
+def _pdf_page_count(content: bytes):
+    """返回 PDF 页数; 无法确定时返回 None。
+
+    优先用 pypdf 精确解析; 未安装或解析异常时退化为字节扫描
+    (对未压缩对象树有效, Elsevier 的摘要预览页正属此类)。"""
+    try:
+        from io import BytesIO
+        import logging
+        # 坏 PDF 会让 pypdf 刷大量恢复日志, 这里只关心页数, 静音其 logger
+        logging.getLogger("pypdf").setLevel(logging.CRITICAL)
+        from pypdf import PdfReader
+        return len(PdfReader(BytesIO(content), strict=False).pages)
+    except ImportError:
+        pass
+    except Exception:
+        return None
+    try:
+        counts = [int(m) for m in re.findall(rb"/Count\s+(\d+)", content)]
+        if counts:
+            return max(counts)
+        n = len(re.findall(rb"/Type\s*/Page(?![sR])", content))
+        if n:
+            return n
+    except Exception:
+        pass
+    return None
+
+
+def _is_elsevier_preview_pdf(content: bytes) -> bool:
+    """判断 Elsevier 返回的 PDF 是否为"摘要预览页"。
+
+    Elsevier Article API 对未授权 / in-press 文章, application/pdf 端点会返回
+    仅含摘要的 1 页预览 PDF(魔数仍是 %PDF、体积也不小), 全文 XML 却可能正常。
+    判据: 能确定页数且 <= 1 页。无法确定页数时返回 False(从宽, 不误杀真全文)。"""
+    pages = _pdf_page_count(content)
+    return pages is not None and pages <= 1
+
+
+def _inspect_pdf(content: bytes):
+    """对历史落库的 PDF 文件分类, 返回 (kind, pages)。
+
+    kind:
+      'broken'  - 非 PDF(魔数不符)或 pypdf 解析直接失败 -> 可安全删除重抓
+      'preview' - 1 页摘要预览页
+      'ok'      - 多页, 视为真全文, 不处理
+      'unknown' - 魔数正常但页数判不出(通常因未装 pypdf) -> 不处理, 绝不当坏文件
+    pages: 页数; 无法确定为 None。"""
+    if not content or b"%PDF" not in content[:1024]:
+        return "broken", 0
+    try:
+        from io import BytesIO
+        import logging
+        logging.getLogger("pypdf").setLevel(logging.CRITICAL)
+        from pypdf import PdfReader
+    except ImportError:
+        # 没装 pypdf: 只能靠字节扫描, 判不出就 unknown(从宽, 不误判为坏)
+        pages = _pdf_page_count(content)
+        if pages is None:
+            return "unknown", None
+        return ("preview" if pages <= 1 else "ok"), pages
+    try:
+        pages = len(PdfReader(BytesIO(content), strict=False).pages)
+    except Exception:
+        return "broken", None
+    if pages <= 0:
+        return "broken", pages
+    return ("preview" if pages == 1 else "ok"), pages
+
+
+def classify_pdf_file(path: str):
+    """并发 worker 入口: 读取并分类单个 PDF 文件路径。
+
+    返回 (path, kind, pages)。除 _inspect_pdf 的四种 kind 外, 另有 IO 结果:
+      'missing'    - 文件不存在
+      'unreadable' - 打开失败(权限等)
+    设计为纯函数(仅 stdlib + pypdf), 可被进程池安全 pickle / 导入。"""
+    try:
+        if not os.path.exists(path):
+            return path, "missing", None
+        with open(path, "rb") as f:
+            content = f.read()
+    except OSError:
+        return path, "unreadable", None
+    kind, pages = _inspect_pdf(content)
+    return path, kind, pages

apps/resm/tasks.py

@@ -11,7 +11,7 @@ from lxml import etree
 from celery import current_app
 from datetime import datetime, timedelta
 import random
-import re
+from .pdf_utils import _is_elsevier_preview_pdf
 from .d_oaurl import download_from_url_playwright
 import asyncio
 import sys
@@ -600,41 +600,6 @@ def _elsevier_fetch_xml(req, paper):
     return True, has_fulltext, None
 
 
-def _pdf_page_count(content: bytes):
-    """返回 PDF 页数; 无法确定时返回 None。
-
-    优先用 pypdf 精确解析; 未安装或解析异常时退化为字节扫描
-    (对未压缩对象树有效, Elsevier 的摘要预览页正属此类)。"""
-    try:
-        from io import BytesIO
-        from pypdf import PdfReader
-        return len(PdfReader(BytesIO(content), strict=False).pages)
-    except ImportError:
-        pass
-    except Exception:
-        return None
-    try:
-        counts = [int(m) for m in re.findall(rb"/Count\s+(\d+)", content)]
-        if counts:
-            return max(counts)
-        n = len(re.findall(rb"/Type\s*/Page(?![sR])", content))
-        if n:
-            return n
-    except Exception:
-        pass
-    return None
-
-
-def _is_elsevier_preview_pdf(content: bytes) -> bool:
-    """判断 Elsevier 返回的 PDF 是否为"摘要预览页"。
-
-    Elsevier Article API 对未授权 / in-press 文章, application/pdf 端点会返回
-    仅含摘要的 1 页预览 PDF(魔数仍是 %PDF、体积也不小), 全文 XML 却可能正常。
-    判据: 能确定页数且 <= 1 页。无法确定页数时返回 False(从宽, 不误杀真全文)。"""
-    pages = _pdf_page_count(content)
-    return pages is not None and pages <= 1
-
-
 def _elsevier_fetch_pdf(req, paper):
     """同一 DOI 取 PDF, 成功落库返回 True。"""
     try:

scripts/sd_download.py

@@ -0,0 +1,311 @@
+#!/usr/bin/env python
+"""独立脚本: 从 ScienceDirect 网页下载排版 PDF。
+
+与 apps.resm 解耦, 独立运行。核心难点是 Cloudflare 人机校验: Playwright 自建
+浏览器带自动化指纹会被 Turnstile 识破而死循环("are you a robot"), 因此推荐
+连接你手动启动的真实 Chrome(由真人过一次验证), 脚本只负责驱动它下载。
+
+前提: 运行方 IP 在机构订阅网段(ScienceDirect 按 IP 授权)。
+
+依赖: playwright, requests, lxml, pypdf(可选, 用于精确判页数)。
+凭证: 默认从项目 config/conf.py 读取 ELSEVIER_API_KEY / ELSEVIER_INST_TOKEN,
+      也可用 --pii 直接给 PII 跳过取号。
+
+用法(推荐 CDP 模式):
+  1) 单独起一个带调试端口的 Chrome(独立档案, 不影响日常浏览器):
+     Windows:
+       & "C:\\Program Files\\Google\\Chrome\\Application\\chrome.exe" \
+         --remote-debugging-port=9222 --user-data-dir="D:\\chrome-sd-profile"
+     Linux:
+       google-chrome --remote-debugging-port=9222 --user-data-dir=/tmp/sd-profile
+  2) 在该 Chrome 里手动打开任一 ScienceDirect 文章, 亲手过掉 Cloudflare 验证。
+  3) 运行本脚本(可一次多篇):
+     python scripts/sd_download.py 10.1016/j.conbuildmat.2026.146897 \
+         --cdp http://localhost:9222 --out ./sd_pdfs
+
+  不加 --cdp 时脚本自行启动浏览器(大概率被 Cloudflare 拦, 仅调试用)。
+
+提示: 批量爬 ScienceDirect 违反 Elsevier 条款且可能导致机构 IP 被封, 仅供少量补抓。
+"""
+import argparse
+import asyncio
+import os
+import re
+import sys
+from io import BytesIO
+
+# 项目根入 sys.path, 以便读取 config/conf.py 的凭证
+ROOT = os.path.dirname(os.path.dirname(os.path.abspath(__file__)))
+if ROOT not in sys.path:
+    sys.path.insert(0, ROOT)
+
+_UA = ("Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 "
+       "(KHTML, like Gecko) Chrome/131.0.0.0 Safari/537.36")
+_STEALTH_ARGS = [
+    "--disable-blink-features=AutomationControlled",
+    "--no-first-run", "--no-default-browser-check",
+    "--disable-infobars", "--disable-extensions", "--disable-notifications",
+]
+_CHALLENGE_KW = ("just a moment", "moment", "checking your browser",
+                 "attention required")
+
+
+# ------------------------------ PII / PDF 工具 ------------------------------
+
+def get_creds():
+    try:
+        from config.conf import ELSEVIER_API_KEY, ELSEVIER_INST_TOKEN
+        return ELSEVIER_API_KEY, ELSEVIER_INST_TOKEN
+    except Exception as e:
+        print(f"[warn] 读取 config/conf.py 凭证失败: {e!r}")
+        return None, None
+
+
+def fetch_pii(doi):
+    """调 Elsevier API(text/xml) 取归一化 PII; 失败返回 None。"""
+    import requests
+    from lxml import etree
+    key, token = get_creds()
+    if not key:
+        return None
+    headers = {"X-ELS-APIKey": key}
+    if token:
+        headers["X-ELS-Insttoken"] = token
+    try:
+        r = requests.get(f"https://api.elsevier.com/content/article/doi/{doi}",
+                         params={"httpAccept": "text/xml"}, headers=headers,
+                         timeout=(3, 30))
+    except requests.RequestException as e:
+        print(f"[warn] 取 PII 请求失败: {e!r}")
+        return None
+    if r.status_code != 200:
+        print(f"[warn] 取 PII 非 200: {r.status_code}")
+        return None
+    try:
+        root = etree.fromstring(r.content)
+    except Exception:
+        return None
+    nodes = root.xpath("//*[local-name()='pii']/text()")
+    if not nodes:
+        return None
+    return re.sub(r"[^A-Za-z0-9]", "", nodes[0])
+
+
+def pdf_page_count(content: bytes):
+    """返回页数, 判不出返回 None。优先 pypdf, 退化字节扫描。"""
+    try:
+        import logging
+        logging.getLogger("pypdf").setLevel(logging.CRITICAL)
+        from pypdf import PdfReader
+        return len(PdfReader(BytesIO(content), strict=False).pages)
+    except ImportError:
+        pass
+    except Exception:
+        return None
+    try:
+        counts = [int(m) for m in re.findall(rb"/Count\s+(\d+)", content)]
+        if counts:
+            return max(counts)
+        n = len(re.findall(rb"/Type\s*/Page(?![sR])", content))
+        if n:
+            return n
+    except Exception:
+        pass
+    return None
+
+
+def classify(content: bytes):
+    """(kind, pages): broken / preview(1页) / ok(多页) / unknown。"""
+    if not content or b"%PDF" not in content[:1024]:
+        return "broken", 0
+    pages = pdf_page_count(content)
+    if pages is None:
+        return "unknown", None
+    if pages <= 0:
+        return "broken", pages
+    return ("preview" if pages == 1 else "ok"), pages
+
+
+# ------------------------------ 浏览器下载 ------------------------------
+
+async def _wait_challenge_cleared(page, rounds=30, interval=2000):
+    for _ in range(rounds):
+        try:
+            await page.wait_for_timeout(interval)
+        except Exception:
+            pass
+        try:
+            title = (await page.title()) or ""
+        except Exception:
+            continue  # 跳转中, 下一轮再看
+        if title and not any(k in title.lower() for k in _CHALLENGE_KW):
+            return True
+    return False
+
+
+async def _find_pdfft_href(page):
+    try:
+        return await page.evaluate(
+            "() => { const a=document.querySelector('a[href*=\"pdfft\"]');"
+            " return a ? a.href : null; }")
+    except Exception:
+        return None
+
+
+async def _grab_pdf(page, url, timeout):
+    # 优先 download 事件
+    try:
+        async with page.expect_download(timeout=min(timeout, 45000)) as dl:
+            try:
+                await page.goto(url, timeout=timeout)
+            except Exception:
+                pass
+        download = await dl.value
+        path = await download.path()
+        if path:
+            with open(path, "rb") as f:
+                data = f.read()
+            if data:
+                return data
+    except Exception:
+        pass
+    # 退化: 拦截内联 application/pdf 响应
+    captured = {}
+
+    async def on_resp(resp):
+        try:
+            if "application/pdf" in resp.headers.get("content-type", ""):
+                captured["b"] = await resp.body()
+        except Exception:
+            pass
+
+    page.on("response", on_resp)
+    try:
+        try:
+            await page.goto(url.replace("?download=true", ""), timeout=timeout)
+        except Exception:
+            pass
+        for _ in range(12):
+            if captured.get("b"):
+                break
+            await page.wait_for_timeout(1000)
+    finally:
+        try:
+            page.remove_listener("response", on_resp)
+        except Exception:
+            pass
+    return captured.get("b")
+
+
+async def download_one(pii, save_path, cdp_url=None, headless=False,
+                       timeout=60000):
+    """返回 (ok, msg)。"""
+    from playwright.async_api import async_playwright
+    article = f"https://www.sciencedirect.com/science/article/pii/{pii}"
+    pdf_url = f"{article}/pdfft?download=true"
+
+    async with async_playwright() as p:
+        connected = bool(cdp_url)
+        if connected:
+            browser = await p.chromium.connect_over_cdp(cdp_url)
+        else:
+            try:
+                browser = await p.chromium.launch(headless=headless,
+                                                   channel="chrome",
+                                                   args=_STEALTH_ARGS)
+            except Exception:
+                browser = await p.chromium.launch(headless=headless,
+                                                   args=_STEALTH_ARGS)
+        page = None
+        try:
+            if connected:
+                ctx = browser.contexts[0] if browser.contexts else await browser.new_context()
+            else:
+                ctx = await browser.new_context(
+                    viewport={"width": 1920, "height": 1080},
+                    user_agent=_UA, locale="en-US", accept_downloads=True)
+            page = await ctx.new_page()
+            page.set_default_timeout(timeout)
+            if not connected:
+                await page.add_init_script(
+                    "Object.defineProperty(navigator,'webdriver',{get:()=>false});")
+
+            try:
+                await page.goto(article, wait_until="domcontentloaded",
+                                timeout=40000)
+            except Exception:
+                pass
+            rounds = 60 if connected else 20
+            if not await _wait_challenge_cleared(page, rounds=rounds):
+                return False, "cloudflare_not_cleared"
+
+            # reload 拿干净文章页
+            try:
+                await page.goto(article, wait_until="domcontentloaded",
+                                timeout=40000)
+                await page.wait_for_timeout(4000)
+            except Exception:
+                pass
+
+            href = await _find_pdfft_href(page) or pdf_url
+            body = await _grab_pdf(page, href, timeout)
+            if not body:
+                return False, "no_pdf_captured"
+            kind, pages = classify(body)
+            if kind != "ok":
+                head = body[:160].decode("utf-8", "replace").replace("\n", " ")
+                return False, f"not_fulltext kind={kind} pages={pages} len={len(body)} head={head!r}"
+            os.makedirs(os.path.dirname(os.path.abspath(save_path)), exist_ok=True)
+            with open(save_path, "wb") as f:
+                f.write(body)
+            return True, f"ok pages={pages} len={len(body)}"
+        finally:
+            try:
+                if connected and page:
+                    await page.close()
+                await browser.close()
+            except Exception:
+                pass
+
+
+# ------------------------------ CLI ------------------------------
+
+async def _run(args):
+    os.makedirs(args.out, exist_ok=True)
+    ok_n = 0
+    for doi in args.doi:
+        doi = doi.strip()
+        pii = args.pii or fetch_pii(doi)
+        if not pii:
+            print(f"[FAIL] {doi}: 取不到 PII")
+            continue
+        save = os.path.join(args.out, doi.replace("/", "_") + ".pdf")
+        print(f"[..] {doi}  PII={pii}  -> {save}")
+        ok, msg = await download_one(pii, save, cdp_url=args.cdp or None,
+                                     headless=args.headless, timeout=args.timeout * 1000)
+        if ok:
+            ok_n += 1
+            print(f"[OK] {doi}: {msg}")
+        else:
+            print(f"[FAIL] {doi}: {msg}")
+    print(f"完成: {ok_n}/{len(args.doi)} 成功")
+
+
+def main():
+    ap = argparse.ArgumentParser(description="从 ScienceDirect 网页下载 PDF(独立脚本)")
+    ap.add_argument("doi", nargs="+", help="一个或多个 DOI")
+    ap.add_argument("--cdp", default="",
+                    help="连接手动启动的 Chrome, 如 http://localhost:9222(推荐)")
+    ap.add_argument("--out", default="./sd_pdfs", help="PDF 输出目录")
+    ap.add_argument("--pii", default="", help="直接指定 PII(仅单篇时用, 跳过 API 取号)")
+    ap.add_argument("--headless", action="store_true", help="无头(非 CDP 模式, 调试用)")
+    ap.add_argument("--timeout", type=int, default=60, help="单步超时(秒)")
+    args = ap.parse_args()
+
+    if sys.platform == "win32":
+        asyncio.set_event_loop_policy(asyncio.WindowsProactorEventLoopPolicy())
+    asyncio.run(_run(args))
+
+
+if __name__ == "__main__":
+    main()