diff --git a/app/platform/site_import/__init__.py b/app/platform/site_import/__init__.py
new file mode 100644
index 0000000..e69de29
diff --git a/app/platform/site_import/safe_fetch.py b/app/platform/site_import/safe_fetch.py
new file mode 100644
index 0000000..af4f3f8
--- /dev/null
+++ b/app/platform/site_import/safe_fetch.py
@@ -0,0 +1,192 @@
+"""site_import 安全抓取原语（spec §3.1）。
+
+连接层 SSRF 校验：自定义 httpcore 后端在 connect_tcp 处做
+anyio.getaddrinfo 解析（异步——单进程零同步 IO 纪律）→ IP 禁段校验 →
+只连已验 IP 字面量。DNS rebinding 的 TOCTOU 由「解析与连接使用同一
+后端的同一结果」闭合。禁止改写 URL host 为 IP（会破坏 TLS 证书校验）——
+SNI/证书由 httpcore 以原 hostname 包 TLS 保持正确
+（httpcore connection.py: start_tls(server_hostname=origin.host)）。
+
+私有 API 依赖（httpx 0.28 / httpcore 1.0.9 钉位，tests/test_safe_fetch.py
+版本探针守卫，升级破坏时立即红）：
+- httpx.AsyncHTTPTransport._pool 属性替换注入校验连接池
+- httpcore.AsyncConnectionPool(network_backend=...)
+- httpcore._backends.anyio.AnyIOStream（anyio 流 → httpcore 流包装）
+- httpcore._exceptions.ConnectError / ConnectTimeout / map_exceptions
+"""
+import ipaddress
+import socket
+import ssl
+import urllib.parse
+
+import anyio
+import certifi
+import httpcore
+import httpx
+from httpcore._backends.anyio import AnyIOStream
+from httpcore._exceptions import ConnectError, ConnectTimeout, map_exceptions
+
+BLOCKED_NETS = [ipaddress.ip_network(n) for n in [
+    "127.0.0.0/8", "10.0.0.0/8", "172.16.0.0/12", "192.168.0.0/16",
+    "169.254.0.0/16", "0.0.0.0/8", "100.64.0.0/10", "::1/128",
+    "fc00::/7", "fe80::/10", "::ffff:0:0/96",
+]]
+ALLOWED_PORTS = {80, 443}
+MAX_REDIRECTS = 5
+USER_AGENT = (
+    "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 "
+    "(KHTML, like Gecko) Chrome/124.0.0.0 Safari/537.36"
+)
+
+
+class BlockedAddressError(Exception):
+    """目标解析到禁段（或端口非法）——连接前拒绝。"""
+
+
+class FetchError(Exception):
+    """抓取失败（URL 非法 / 端口禁 / 重定向超限 / 请求层错误）。"""
+
+
+def is_blocked_ip(ip: str) -> bool:
+    """禁段判定；非法 IP 串一律视为禁（fail-closed）。"""
+    try:
+        addr = ipaddress.ip_address(ip)
+    except ValueError:
+        return True
+    return any(addr in net for net in BLOCKED_NETS)
+
+
+def _is_blocked_literal(hostname: str) -> bool:
+    """URL 层的 host 禁段预检——只拒「IP 字面量落在禁段」的 host。
+
+    普通域名（非 IP 字面量）此处放行，交由连接层解析后按 is_blocked_ip
+    校验（is_blocked_ip 对非 IP 串 fail-closed 为 True，那是给解析结果
+    用的语义，不能套在域名上）。
+    """
+    try:
+        addr = ipaddress.ip_address(hostname)
+    except ValueError:
+        return False
+    return is_blocked_ip(str(addr))
+
+
+def _sockaddr_ip(raw) -> str:
+    """getaddrinfo 的 sockaddr[0] 兼容 str / 打包 bytes 两种形态（IPv6 bytes）。"""
+    if isinstance(raw, (bytes, bytearray)):
+        return str(ipaddress.ip_address(bytes(raw)))
+    return str(raw)
+
+
+class ValidatingBackend(httpcore.AsyncNetworkBackend):
+    """connect_tcp 钩子：anyio.getaddrinfo 解析 → 逐候选禁段校验 → 只连已验 IP 字面量。
+
+    评审折入的两个实现陷阱：
+    1. anyio 不重导出 socket 常量——AF_UNSPEC/SOCK_STREAM 用 socket 模块；
+    2. 默认后端 anyio.connect_tcp(remote_host=host) 会对 hostname 内部重新做
+       DNS 解析——把 rebinding TOCTOU 重新打开。本实现只把「已验 IP 字面量」
+       递给连接调用（anyio 对 IP 字面量跳过 DNS 直连），原 hostname 不再进
+       任何会做 DNS 的路径。connect_unix_socket 不实现（基类默认拒绝）。
+    """
+
+    async def connect_tcp(
+        self,
+        host: str,
+        port: int,
+        timeout: float | None = None,
+        local_address: str | None = None,
+        socket_options=None,
+    ):
+        if port not in ALLOWED_PORTS:
+            raise BlockedAddressError(
+                f"port {port} not in allowed {sorted(ALLOWED_PORTS)}")
+        if socket_options is None:
+            socket_options = []
+        exc_map = {
+            TimeoutError: ConnectTimeout,
+            OSError: ConnectError,
+            anyio.BrokenResourceError: ConnectError,
+        }
+        with map_exceptions(exc_map):
+            infos = await anyio.getaddrinfo(
+                host, port, family=socket.AF_UNSPEC, type=socket.SOCK_STREAM)
+            validated: str | None = None
+            for _family, _type, _proto, _canon, sockaddr in infos:
+                ip = _sockaddr_ip(sockaddr[0])
+                if is_blocked_ip(ip):
+                    raise BlockedAddressError(
+                        f"{host!r} resolves to blocked address {ip}")
+                if validated is None:
+                    validated = ip
+            if validated is None:  # pragma: no cover - getaddrinfo 空结果防御
+                raise BlockedAddressError(f"{host!r} resolved to no addresses")
+            with anyio.fail_after(timeout):
+                stream = await anyio.connect_tcp(
+                    remote_host=validated, remote_port=port, local_host=local_address)
+                for option in socket_options:
+                    stream._raw_socket.setsockopt(*option)  # type: ignore[attr-defined]
+        return AnyIOStream(stream)
+
+    async def sleep(self, seconds: float) -> None:
+        await anyio.sleep(seconds)
+
+
+def _make_client(timeout: float = 10.0) -> httpx.AsyncClient:
+    """校验后端注入的 client（私有口 _pool 替换——版本探针测试钉住）。"""
+    transport = httpx.AsyncHTTPTransport()
+    transport._pool = httpcore.AsyncConnectionPool(
+        ssl_context=ssl.create_default_context(cafile=certifi.where()),
+        network_backend=ValidatingBackend(),
+    )
+    return httpx.AsyncClient(
+        transport=transport,
+        timeout=timeout,
+        follow_redirects=False,
+        headers={"User-Agent": USER_AGENT},
+    )
+
+
+def _validate_url(url: str) -> None:
+    """URL 层预检：scheme 白名单 + host 禁段 + 端口白名单（连接层校验的前置快速失败）。"""
+    try:
+        parsed = urllib.parse.urlsplit(url)
+        port = parsed.port
+    except ValueError as exc:
+        raise FetchError(f"invalid URL: {url!r}") from exc
+    if parsed.scheme not in ("http", "https"):
+        raise FetchError(f"scheme not allowed: {parsed.scheme!r} ({url!r})")
+    if not parsed.hostname:
+        raise FetchError(f"URL without host: {url!r}")
+    if _is_blocked_literal(parsed.hostname):
+        raise FetchError(f"URL host in blocked range: {parsed.hostname}")
+    if port is None:
+        port = 443 if parsed.scheme == "https" else 80
+    if port not in ALLOWED_PORTS:
+        raise FetchError(f"port {port} not allowed: {url!r}")
+
+
+async def fetch(url: str, timeout: float = 10.0) -> httpx.Response:
+    """单页安全抓取：URL 预检 + 逐跳手动重定向（≤5 跳，每跳重过完整校验链）。
+
+    双层防线：本函数的 URL 层预检挡住字面量私网/非标端口；ValidatingBackend
+    在连接层对每一跳的 DNS 解析结果做禁段校验（防 rebinding）。网络层错误
+    统一包装为 FetchError（保留 __cause__）。
+    """
+    _validate_url(url)
+    client = _make_client(timeout)
+    current = url
+    redirects = 0
+    try:
+        while True:
+            response = await client.get(current)
+            if not response.has_redirect_location:
+                return response
+            redirects += 1
+            if redirects > MAX_REDIRECTS:
+                raise FetchError(
+                    f"too many redirects (>{MAX_REDIRECTS}) at {current!r}")
+            current = urllib.parse.urljoin(current, response.headers["location"])
+            _validate_url(current)
+    except (httpx.HTTPError, httpx.InvalidURL, BlockedAddressError, OSError) as exc:
+        raise FetchError(f"fetch failed for {url!r}: {exc}") from exc
+    finally:
+        await client.aclose()
diff --git a/tests/test_safe_fetch.py b/tests/test_safe_fetch.py
new file mode 100644
index 0000000..d1c5f29
--- /dev/null
+++ b/tests/test_safe_fetch.py
@@ -0,0 +1,187 @@
+"""safe_fetch：连接层 SSRF 校验（spec §3.1——防 DNS rebinding）。"""
+import inspect
+import socket
+
+import httpx
+import pytest
+
+from app.platform.site_import import safe_fetch
+
+
+def _mock_client_factory(handler):
+    """redirect 类测试的打桩口：换掉 _make_client，注入 MockTransport client。"""
+
+    def factory(timeout: float = 10.0) -> httpx.AsyncClient:
+        return httpx.AsyncClient(
+            transport=httpx.MockTransport(handler), follow_redirects=False)
+
+    return factory
+
+
+class _FakeRawSocket:
+    def setsockopt(self, *args, **kwargs):
+        pass
+
+
+class _FakeAnyioStream:
+    """anyio 流替身：吐一条完整 HTTP/1.1 200 响应（经 AnyIOStream 包装喂 httpcore）。"""
+
+    def __init__(self) -> None:
+        self._buf = (
+            b"HTTP/1.1 200 OK\r\n"
+            b"Content-Length: 2\r\n"
+            b"Connection: close\r\n"
+            b"\r\n"
+            b"ok"
+        )
+        self._raw_socket = _FakeRawSocket()
+
+    async def receive(self, max_bytes: int) -> bytes:
+        chunk, self._buf = self._buf[:max_bytes], self._buf[max_bytes:]
+        return chunk
+
+    async def send(self, item: bytes) -> None:
+        pass
+
+    async def aclose(self) -> None:
+        pass
+
+    def extra(self, *args, **kwargs):
+        return None
+
+
+class TestVersionPin:
+    def test_httpx私有口存在(self):
+        """httpx/httpcore 升级破坏私有 API 时立即红（spec 要求的版本钉位）——真断言，禁永真。"""
+        import httpcore
+        t = httpx.AsyncHTTPTransport()
+        assert hasattr(t, "_pool")
+        assert "network_backend" in inspect.signature(
+            httpcore.AsyncConnectionPool.__init__).parameters
+
+    def test_httpcore私有导出口存在(self):
+        """safe_fetch 消费的 httpcore 私有符号（AnyIOStream 流包装 / 异常映射口）逐个在位。"""
+        from httpcore._backends.anyio import AnyIOStream
+        from httpcore._exceptions import ConnectError, ConnectTimeout, map_exceptions
+        assert callable(map_exceptions)
+        assert issubclass(ConnectTimeout, Exception)
+        assert issubclass(ConnectError, Exception)
+
+
+class TestIsBlockedIp:
+    @pytest.mark.parametrize("ip", [
+        "127.0.0.1", "10.1.2.3", "172.16.0.1", "172.31.255.255",
+        "192.168.1.1", "169.254.1.1", "0.0.0.0", "100.64.0.1",
+        "::1", "fd00::1", "fe80::1", "::ffff:127.0.0.1", "::ffff:10.0.0.1",
+    ])
+    def test_私网段全拒(self, ip):
+        assert safe_fetch.is_blocked_ip(ip) is True
+
+    @pytest.mark.parametrize("ip", ["8.8.8.8", "1.1.1.1", "47.254.176.10", "2606:4700::1"])
+    def test_公网放行(self, ip):
+        assert safe_fetch.is_blocked_ip(ip) is False
+
+    def test_非法IP串视为拒(self):
+        assert safe_fetch.is_blocked_ip("not-an-ip") is True
+
+
+class TestValidatingBackend:
+    async def test_connect_tcp_拒绝私网IP字面量(self):
+        backend = safe_fetch.ValidatingBackend()
+        with pytest.raises(safe_fetch.BlockedAddressError):
+            await backend.connect_tcp("127.0.0.1", 80)
+        with pytest.raises(safe_fetch.BlockedAddressError):
+            await backend.connect_tcp("10.0.0.1", 443)
+        # （连接层校验逻辑用 IP 字面量直接钉，不做真实域名 DNS 测试）
+
+    async def test_非法端口拒绝(self):
+        backend = safe_fetch.ValidatingBackend()
+        with pytest.raises(safe_fetch.BlockedAddressError):
+            await backend.connect_tcp("8.8.8.8", 8080)
+
+
+class TestFetch:
+    async def test_非法端口拒绝(self):
+        with pytest.raises(safe_fetch.FetchError):
+            await safe_fetch.fetch("http://example.com:8080/")
+
+    async def test_私网URL拒绝(self):
+        with pytest.raises(safe_fetch.FetchError):
+            await safe_fetch.fetch("http://127.0.0.1/x")
+        with pytest.raises(safe_fetch.FetchError):
+            await safe_fetch.fetch("http://10.0.0.1/x")
+
+    async def test_非http协议拒绝(self):
+        with pytest.raises(safe_fetch.FetchError):
+            await safe_fetch.fetch("ftp://example.com/x")
+        with pytest.raises(safe_fetch.FetchError):
+            await safe_fetch.fetch("file:///etc/passwd")
+
+    async def test_逐跳重定向每跳重校验(self, monkeypatch):
+        """302 → Location 指向私网 IP → 必须以 FetchError 终结（安全关键路径）。"""
+        served = []
+
+        def handler(request: httpx.Request) -> httpx.Response:
+            served.append(str(request.url))
+            return httpx.Response(302, headers={"Location": "http://10.0.0.2/evil"})
+
+        monkeypatch.setattr(safe_fetch, "_make_client", _mock_client_factory(handler))
+        with pytest.raises(safe_fetch.FetchError):
+            await safe_fetch.fetch("http://example.com/start")
+        # 首跳（公网）发生、第二跳（私网 Location）在 URL 层即被拦，未发起
+        assert served == ["http://example.com/start"]
+
+    async def test_重定向上限5跳(self, monkeypatch):
+        """>5 跳 302 链 → FetchError。"""
+        calls = []
+
+        def handler(request: httpx.Request) -> httpx.Response:
+            calls.append(request.url.path)
+            return httpx.Response(302, headers={"Location": "/next"})
+
+        monkeypatch.setattr(safe_fetch, "_make_client", _mock_client_factory(handler))
+        with pytest.raises(safe_fetch.FetchError):
+            await safe_fetch.fetch("http://example.com/start")
+        # 首跳 + 5 次跟随 = 6 个请求；第 6 个 Location 不再跟
+        assert len(calls) == 6
+
+    async def test_五跳内重定向正常返回(self, monkeypatch):
+        """恰好 5 跳 302 + 终点 200 → 正常返回（上限边界正向钉位）。"""
+        locations = iter(["/r1", "/r2", "/r3", "/r4", "/final"])
+        n_redirects = 0
+
+        def handler(request: httpx.Request) -> httpx.Response:
+            nonlocal n_redirects
+            loc = next(locations, None)
+            if loc is None:
+                return httpx.Response(200, text="ok")
+            n_redirects += 1
+            return httpx.Response(302, headers={"Location": loc})
+
+        monkeypatch.setattr(safe_fetch, "_make_client", _mock_client_factory(handler))
+        resp = await safe_fetch.fetch("http://example.com/start")
+        assert resp.status_code == 200
+        assert resp.text == "ok"
+        assert n_redirects == 5
+
+    async def test_请求真实走校验后端(self, monkeypatch):
+        """_make_client 的请求确实路由经 ValidatingBackend（连接层钩子被调用）。"""
+        events = []
+
+        async def fake_getaddrinfo(host, port, **kwargs):
+            events.append(("resolve", host))
+            return [(socket.AF_INET, socket.SOCK_STREAM, 6, "", ("93.184.216.34", port))]
+
+        async def fake_connect_tcp(remote_host, remote_port, **kwargs):
+            events.append(("connect", remote_host, remote_port))
+            return _FakeAnyioStream()
+
+        monkeypatch.setattr(safe_fetch.anyio, "getaddrinfo", fake_getaddrinfo)
+        monkeypatch.setattr(safe_fetch.anyio, "connect_tcp", fake_connect_tcp)
+
+        resp = await safe_fetch.fetch("http://example.com/")
+        assert resp.status_code == 200
+        assert resp.text == "ok"
+        assert ("resolve", "example.com") in events
+        # 连接目标是已验 IP 字面量而非原 hostname（DNS rebinding TOCTOU 闭合点）
+        assert ("connect", "93.184.216.34", 80) in events