diff --git a/README.md b/README.md
index 8ba2e39..92883a1 100644
--- a/README.md
+++ b/README.md
@@ -607,6 +607,7 @@ docker compose --profile gateway up -d
 
 - `POST /api/cart/add` — 加购，入参 `{item_url, quantity?, variant_id?, choice?}`
 - `POST /api/cart/status` — 调 cart count API，返回购物车商品件数
+  （空车是正常结果：`count=0, raw_status="101"`；获取失败才报错 5002）
 - `POST /api/cart/clear` — 清空购物车（UI 点击 `button[aria-label="削除"]`）
 - `POST /api/cart/remove` — 删除指定 `item_id`
 
diff --git a/app/trading/api/routes/cart.py b/app/trading/api/routes/cart.py
index bbbc786..ecb7ad0 100644
--- a/app/trading/api/routes/cart.py
+++ b/app/trading/api/routes/cart.py
@@ -88,6 +88,7 @@ async def cart_status(
     """查询购物车状态（轻量）
 
     只调 cart count JSONP API，不渲染整页。返回登录态、商品件数与站点状态码。
+    空车是正常结果：count=0 且 raw_status="101"；获取失败走错误码 5002。
     """
     site = _require_site(container)
     result = await site.cart_status()  # type: ignore[union-attr]
diff --git a/app/trading/worker/site_interact.py b/app/trading/worker/site_interact.py
index f684cde..d627ae2 100644
--- a/app/trading/worker/site_interact.py
+++ b/app/trading/worker/site_interact.py
@@ -6,6 +6,10 @@ data/evidence/checkout-research-20260811/NOTES.md）：
 - clear_cart、remove_item 用 UI 点击 `button[aria-label^="削除"]` 路径实现，
   2026-08-11 用真账号跑通下单测试时确认实际 aria-label 是「削除する」而非旧探针
   记录的「削除」，selector 已改前缀匹配；modal 是否存在仍未实测确认
+- cart count JSONP API 契约 2026-08-16 真账号实测（scripts/probe_cart_count.py +
+  .probe/cart_count/）：status=101 + count="" 是**空车**（合法响应，记 count=0），
+  status=300（referer/sid 被拒）才是获取失败——此前一律按失败处理，
+  空车时 clear_cart 末尾校验拿 -1、开单前清理被误判失败
 - enter_checkout 已实现到「进入 session upgrade 密码页并尝试自动复核」：购物车页
   点击真正的「購入手続き」（注意页面上还有个促销用的「カード入会＆購入手続き」
   按钮，selector 必须精确匹配，不能 .first 模糊选）后，即使 SSO 会话仍有效，
@@ -133,6 +137,11 @@ _BASKET_PATH = "/rms/mall/bss/cartadd/set"
 _CART_PAGE = auth_site.RAKUTEN_CART_URL
 _CART_COUNT_API = "https://cart-api.step.rakuten.co.jp/rms/mall/cart/count/all/jsonp/"
 
+# cart count API 的「空车」状态码（2026-08-16 真账号实测，
+# scripts/probe_cart_count.py）：status=101 + message "value not found." +
+# count="" 表示购物车为空，是合法响应而非获取失败；status=300 之类才是被拒
+_CART_EMPTY_STATUS = "101"
+
 # 购物车页未登录标记（旧 marker；新 SPA 上不可靠，这里只作辅助判据）
 _LEGACY_LOGGED_OUT_MARKER = auth_site.RAKUTEN_LOGGED_OUT_MARKER
 
@@ -942,6 +951,7 @@ class SiteInteractor:
 
         策略（探针实测最稳的两步）：
         1. 打 cart count JSONP API：status=100 且 count>=1 才算「购物车非空」
+           （status=101 是空车，count 记 0，见 _query_cart_count）
         2. 打开 cart 页等 SPA 渲染，在 HTML 里找 item_id
 
         Returns:
@@ -974,7 +984,8 @@ class SiteInteractor:
 
         返回 {logged_in, count, raw_status}。
         count 是站点返回的购物车里商品总件数（含数量，非 SKU 数）。
-        raw_status 是站点的状态码字符串，"100" 表示正常。
+        raw_status 是站点的状态码字符串："100" 非空、"101" 空车（count=0）；
+        其余 status 属「获取失败」，抛 CartOperationError 而不是返回。
         """
         async with self._lock:
             await self._auth_session.require_logged_in("rakuten")
@@ -999,7 +1010,8 @@ class SiteInteractor:
         - 若 SPA 把按钮渲染在 iframe 里，selector 失败需实测后调整
         - Rakuten cart item 卡片无 data-testid，本方法不依赖 DOM 结构定位
 
-        返回 {removed_count, cart_count}；cart_count=-1 表示末尾 count API 调用失败。
+        返回 {removed_count, cart_count}；cart_count=-1 表示末尾 count API 调用失败
+        （空车属正常结果返回 0，见 _query_cart_count 的 status=101 处理）。
         """
         async with self._lock:
             await self._auth_session.require_logged_in("rakuten")
@@ -1125,8 +1137,14 @@ class SiteInteractor:
     async def _query_cart_count(self) -> tuple[str, int]:
         """调 cart count JSONP API，返回 (raw_status, count)
 
-        解析失败、status 非 100 都抛 CartOperationError——这是站点在告诉我们
-        「请求被拒了」，常见原因是 Referer 错或 cookie 失效。
+        站点契约（2026-08-16 真账号实测，scripts/probe_cart_count.py +
+        .probe/cart_count/）——必须区分「车是空的」与「获取失败」：
+        - status "100"：购物车非空，count 是数字字符串
+        - status "101"（message "value not found."）：**购物车为空**，count 是
+          空串——这是合法结果，返回 ("101", 0)，不能当失败
+        - 其余 status（实测如 "300"：referer 缺失 / sid 不可用）或响应无法解析，
+          才是「获取失败」，抛 CartOperationError——常见原因是 Referer 错或
+          cookie 失效
         """
         resp = await self._context.request.get(
             _CART_COUNT_API + "?sid=1010",
@@ -1137,6 +1155,8 @@ class SiteInteractor:
         if not status_match:
             raise CartOperationError(f"cart count 响应无法解析：{body[:200]!r}")
         raw_status = status_match.group(1)
+        if raw_status == _CART_EMPTY_STATUS:
+            return raw_status, 0
         if raw_status != "100":
             raise CartOperationError(
                 f"cart count API 异常：status={raw_status} body={body[:200]!r}"
diff --git a/scripts/probe_cart_count.py b/scripts/probe_cart_count.py
new file mode 100644
index 0000000..41173cd
--- /dev/null
+++ b/scripts/probe_cart_count.py
@@ -0,0 +1,126 @@
+"""cart count API 探针：实测「空购物车」与「获取失败」两种响应形态
+
+背景：_query_cart_count 目前只认 status=="100"，其余一律 CartOperationError。
+需要真账号确认：购物车为空时 cart-api.step.rakuten.co.jp 到底返回什么——
+如果空车响应与「请求被拒」长的不一样却被同一错误吞掉，就无法区分
+「车是空的」与「获取失败」。
+
+只读探测，不做任何加购/删除操作。
+
+用法：
+    .venv/Scripts/python.exe scripts/probe_cart_count.py
+    .venv/Scripts/python.exe scripts/probe_cart_count.py --headful
+"""
+from __future__ import annotations
+
+import argparse
+import asyncio
+import sys
+from pathlib import Path
+
+sys.path.insert(0, str(Path(__file__).resolve().parent.parent))
+
+from app.shared.config import get_settings  # noqa: E402
+from app.trading.core import auth_site  # noqa: E402
+
+PROBE_DIR = Path(__file__).resolve().parent.parent / ".probe" / "cart_count"
+PROBE_DIR.mkdir(parents=True, exist_ok=True)
+
+CART_COUNT_API = "https://cart-api.step.rakuten.co.jp/rms/mall/cart/count/all/jsonp/"
+CART_PAGE = auth_site.RAKUTEN_CART_URL
+
+
+def save(name: str, content: str) -> Path:
+    path = PROBE_DIR / name
+    path.write_text(content, encoding="utf-8")
+    print(f"  saved -> {path} ({len(content)} bytes)")
+    return path
+
+
+async def call_count_api(context, *, referer: str | None, tag: str) -> None:
+    headers = {"Referer": referer} if referer else {}
+    resp = await context.request.get(CART_COUNT_API + "?sid=1010", headers=headers)
+    body = await resp.text()
+    print(f"  [{tag}] http_status={resp.status} body={body!r}")
+    save(f"{tag}.txt", f"http_status={resp.status}\n{body}")
+
+
+async def run(*, headful: bool) -> int:
+    from playwright.async_api import async_playwright
+
+    settings = get_settings()
+    state_path = settings.auth_state_path / "rakuten_state.json"
+    if not state_path.exists():
+        print(f"找不到登录态文件：{state_path}")
+        return 1
+
+    async with async_playwright() as pw:
+        browser = await pw.chromium.launch(
+            headless=not headful,
+            channel=settings.browser_channel or None,
+            proxy=settings.playwright_proxy,
+            args=["--no-first-run", "--disable-blink-features=AutomationControlled"],
+        )
+        context = await browser.new_context(
+            storage_state=state_path,
+            user_agent=auth_site.RAKUTEN_USER_AGENT,
+            locale="ja-JP",
+            timezone_id="Asia/Tokyo",
+            viewport={"width": 390, "height": 844},
+            is_mobile=True,
+            has_touch=True,
+        )
+
+        print("=== 1. 带正确 Referer 调 cart count API（生产路径）===")
+        await call_count_api(context, referer=CART_PAGE, tag="10-with-referer")
+
+        print("=== 2. 不带 Referer 调 cart count API（观测「被拒」形态）===")
+        await call_count_api(context, referer=None, tag="11-no-referer")
+
+        print("=== 3. 错误 sid 调 cart count API（另一种异常入参）===")
+        resp = await context.request.get(
+            CART_COUNT_API + "?sid=999999", headers={"Referer": CART_PAGE}
+        )
+        body = await resp.text()
+        print(f"  [bad-sid] http_status={resp.status} body={body!r}")
+        save("12-bad-sid.txt", f"http_status={resp.status}\n{body}")
+
+        print("=== 4. 打开购物车页，看当前车状态（只读）===")
+        page = await context.new_page()
+        await page.goto(CART_PAGE, wait_until="domcontentloaded", timeout=30_000)
+        await page.wait_for_timeout(5000)
+        state = await page.evaluate(
+            """() => {
+                const s = window.__INITIAL_STATE__;
+                if (!s || !s.cart) return {has_state: !!s, keys: s ? Object.keys(s) : []};
+                return {
+                    has_state: true,
+                    cart_keys: Object.keys(s.cart),
+                    shopUrlList_len: Array.isArray(s.cart.shopUrlList) ? s.cart.shopUrlList.length : null,
+                };
+            }"""
+        )
+        print(f"  __INITIAL_STATE__.cart: {state}")
+        html = await page.content()
+        save("20-cart-page.html", html)
+        delete_btns = await page.locator('button[aria-label^="削除"]').count()
+        print(f"  削除按钮数={delete_btns} final_url={page.url}")
+
+        print("=== 5. 车页打开后再调一次 count API（贴近 clear_cart 末尾场景）===")
+        await call_count_api(context, referer=CART_PAGE, tag="21-after-cart-page")
+
+        await browser.close()
+
+    print(f"\n探针输出目录：{PROBE_DIR}")
+    return 0
+
+
+async def main() -> int:
+    parser = argparse.ArgumentParser()
+    parser.add_argument("--headful", action="store_true")
+    args = parser.parse_args()
+    return await run(headful=args.headful)
+
+
+if __name__ == "__main__":
+    raise SystemExit(asyncio.run(main()))
diff --git a/scripts/verify_cart_empty.py b/scripts/verify_cart_empty.py
new file mode 100644
index 0000000..f050028
--- /dev/null
+++ b/scripts/verify_cart_empty.py
@@ -0,0 +1,51 @@
+"""真账号验证：空车场景下 cart_status / clear_cart 不再被误判为获取失败
+
+修复前行为（2026-08-16 探针实测）：空车时 cart count API 返回 status=101，
+_query_cart_count 一律当失败抛 CartOperationError → cart_status 报错 5002、
+clear_cart 末尾校验拿 cart_count=-1（runner 据此误判「开单前清理未清空」）。
+修复后：status=101 识别为合法空车，count=0。
+
+用法：
+    .venv/Scripts/python.exe scripts/verify_cart_empty.py
+"""
+from __future__ import annotations
+
+import asyncio
+import sys
+from pathlib import Path
+
+sys.path.insert(0, str(Path(__file__).resolve().parent.parent))
+
+from app.shared.config import get_settings  # noqa: E402
+from app.trading.services.auth_session import AuthSession  # noqa: E402
+from app.trading.worker.site_interact import SiteInteractor  # noqa: E402
+
+
+async def run() -> int:
+    settings = get_settings()
+    auth = AuthSession(settings)
+    await auth.start()
+    site = SiteInteractor(auth_session=auth, settings=settings)
+    await site.start()
+    try:
+        status = await site.cart_status()
+        print(f"cart_status -> {status}")
+        assert status["logged_in"] is True
+        assert status["count"] == 0, f"预期空车 count=0，实际 {status['count']}"
+        assert status["raw_status"] == "101", f"预期 raw_status=101，实际 {status['raw_status']}"
+
+        cleared = await site.clear_cart()
+        print(f"clear_cart  -> {cleared}")
+        assert cleared["cart_count"] == 0, (
+            f"空车 clear 后 cart_count 应为 0（修复前是 -1），实际 {cleared['cart_count']}"
+        )
+
+        print("\n验证通过：空车按正常结果返回（count=0 / raw_status=101），未误判为获取失败")
+        return 0
+    finally:
+        await site.close()
+        await auth.close()
+
+
+if __name__ == "__main__":
+    raise SystemExit(asyncio.run(run()))
diff --git a/tests/test_site_interact.py b/tests/test_site_interact.py
index 2494b24..d843020 100644
--- a/tests/test_site_interact.py
+++ b/tests/test_site_interact.py
@@ -1138,4 +1138,80 @@ async def test_dump_debug_snapshot_swallows_its_own_errors(tmp_path):
     assert list((tmp_path / "t1").glob("debug-*")) == []
 
 
+# ---- _query_cart_count：空车（status=101）与获取失败（其他 status）必须区分 ----
+#
+# 响应 body 均为 2026-08-16 真账号实测原样（scripts/probe_cart_count.py +
+# .probe/cart_count/）：空车是合法响应，当失败抛错会让 clear_cart 末尾校验拿 -1、
+# 开单前清理被 runner 误判为「未清空」。
+
+
+class _FakeCartCountRequest:
+    """APIRequestContext 替身：回固定 body，记录入参"""
+
+    def __init__(self, body: str):
+        self._body = body
+        self.calls: list[tuple[str, dict[str, str]]] = []
+
+    async def get(self, url: str, headers: dict[str, str] | None = None) -> Any:
+        self.calls.append((url, headers or {}))
+
+        class _Resp:
+            def __init__(self, text: str):
+                self._text = text
+
+            async def text(self) -> str:
+                return self._text
+
+        return _Resp(self._body)
+
+
+class _FakeCartCountContext:
+    def __init__(self, body: str):
+        self.request = _FakeCartCountRequest(body)
+
+
+def _build_cart_count_site(body: str) -> SiteInteractor:
+    site = SiteInteractor(auth_session=None, settings=None)  # type: ignore[arg-type]
+    site._context = _FakeCartCountContext(body)  # type: ignore[assignment]
+    return site
+
+
+async def test_query_cart_count_non_empty_returns_count():
+    site = _build_cart_count_site(
+        'callBack({"status":"100","message":"success.","count":"3"})'
+    )
+
+    raw_status, count = await site._query_cart_count()
+
+    assert (raw_status, count) == ("100", 3)
+
+
+async def test_query_cart_count_empty_cart_is_not_a_failure():
+    """status=101 + count="" 是空车（合法响应），返回 ("101", 0) 而不是抛错"""
+    site = _build_cart_count_site(
+        'callBack({"status":"101","message":"value not found.","count":""})'
+    )
+
+    raw_status, count = await site._query_cart_count()
+
+    assert (raw_status, count) == ("101", 0)
+
+
+async def test_query_cart_count_rejected_request_raises():
+    """status=300（referer/sid 被站点拒绝）才是「获取失败」"""
+    site = _build_cart_count_site(
+        'callBack({"status":"300","message":"referer is empty value.","count":""})'
+    )
+
+    with pytest.raises(CartOperationError):
+        await site._query_cart_count()
+
+
+async def test_query_cart_count_unparseable_body_raises():
+    site = _build_cart_count_site("<html>not jsonp</html>")
+
+    with pytest.raises(CartOperationError):
+        await site._query_cart_count()
+
+
 # ---- helper ----