diff --git a/app/routers/erp_login.py b/app/routers/erp_login.py
index 390d526..f7537c7 100644
--- a/app/routers/erp_login.py
+++ b/app/routers/erp_login.py
@@ -51,16 +51,6 @@ def _scene(ticket: str, session_id: int | None) -> str:
     return scene
 
 
-def _erp_status_error_detail(response: httpx.Response) -> Any:
-    try:
-        data = response.json()
-    except ValueError:
-        return None
-    if isinstance(data, dict):
-        return data.get("detail")
-    return None
-
-
 def _action_response(data: dict[str, Any]) -> ErpLoginActionResponse:
     return ErpLoginActionResponse(
         status=str(data.get("status") or ""),
@@ -72,8 +62,7 @@ async def _read_erp_json(response: httpx.Response) -> dict[str, Any]:
     try:
         response.raise_for_status()
     except httpx.HTTPStatusError as exc:
-        detail = _erp_status_error_detail(exc.response) or "ERP扫码登录服务暂时不可用"
-        raise HTTPException(status_code=502, detail=detail) from exc
+        raise HTTPException(status_code=502, detail="ERP扫码登录服务暂时不可用") from exc
     try:
         data = response.json()
     except ValueError as exc:
diff --git a/app/services/erp_login_security.py b/app/services/erp_login_security.py
index 707ade5..d4f320b 100644
--- a/app/services/erp_login_security.py
+++ b/app/services/erp_login_security.py
@@ -6,9 +6,9 @@ from uuid import uuid4
 from fastapi import HTTPException
 
 
-SERVICE_TIMESTAMP_HEADER = "x-service-timestamp"
-SERVICE_NONCE_HEADER = "x-service-nonce"
-SERVICE_SIGNATURE_HEADER = "x-service-signature"
+SERVICE_TIMESTAMP_HEADER = "X-ERP-QR-Timestamp"
+SERVICE_NONCE_HEADER = "X-ERP-QR-Nonce"
+SERVICE_SIGNATURE_HEADER = "X-ERP-QR-Signature"
 
 _seen_nonces: dict[str, int] = {}
 
diff --git a/tests/test_erp_login.py b/tests/test_erp_login.py
index 23531ce..5e0e753 100644
--- a/tests/test_erp_login.py
+++ b/tests/test_erp_login.py
@@ -14,6 +14,9 @@ from app.services import wechat
 
 
 SERVICE_SECRET = "test-erp-secret"
+TIMESTAMP_HEADER = "X-ERP-QR-Timestamp"
+NONCE_HEADER = "X-ERP-QR-Nonce"
+SIGNATURE_HEADER = "X-ERP-QR-Signature"
 
 
 def _json_bytes(payload: dict) -> bytes:
@@ -47,9 +50,9 @@ def _signed_headers(
     timestamp = str(int(time.time()))
     nonce = uuid4().hex
     return {
-        "x-service-timestamp": timestamp,
-        "x-service-nonce": nonce,
-        "x-service-signature": _test_signature(method, path, timestamp, nonce, body, secret),
+        TIMESTAMP_HEADER: timestamp,
+        NONCE_HEADER: nonce,
+        SIGNATURE_HEADER: _test_signature(method, path, timestamp, nonce, body, secret),
         "content-type": "application/json",
     }
 
@@ -81,7 +84,7 @@ def test_qrcode_rejects_missing_or_bad_service_signature(monkeypatch):
         headers={"content-type": "application/json"},
     )
     bad_headers = _signed_headers("POST", "/api/erp-login/qrcode", body)
-    bad_headers["x-service-signature"] = "bad-signature"
+    bad_headers[SIGNATURE_HEADER] = "bad-signature"
     bad = client.post("/api/erp-login/qrcode", content=body, headers=bad_headers)
 
     assert missing.status_code == 401
@@ -147,8 +150,13 @@ def test_confirm_gets_phone_signs_erp_request_with_base_path_and_hides_auth_sess
         captured["body"] = request.content
         captured["headers"] = request.headers
         assert request.url.path == "/erp-prefix/api/auth/qr-login/sessions/123/confirm"
-        timestamp = request.headers["x-service-timestamp"]
-        nonce = request.headers["x-service-nonce"]
+        raw_header_names = {name.decode("ascii") for name, _ in request.headers.raw}
+        assert TIMESTAMP_HEADER in raw_header_names
+        assert NONCE_HEADER in raw_header_names
+        assert SIGNATURE_HEADER in raw_header_names
+        assert "x-service-timestamp" not in request.headers
+        timestamp = request.headers[TIMESTAMP_HEADER]
+        nonce = request.headers[NONCE_HEADER]
         expected = _test_signature(
             "POST",
             "/erp-prefix/api/auth/qr-login/sessions/123/confirm",
@@ -156,7 +164,7 @@ def test_confirm_gets_phone_signs_erp_request_with_base_path_and_hides_auth_sess
             nonce,
             request.content,
         )
-        assert hmac.compare_digest(request.headers["x-service-signature"], expected)
+        assert hmac.compare_digest(request.headers[SIGNATURE_HEADER], expected)
         return httpx.Response(
             200,
             json={
@@ -192,6 +200,30 @@ def test_confirm_gets_phone_signs_erp_request_with_base_path_and_hides_auth_sess
     assert erp_body["nonce"]
 
 
+def test_erp_http_status_error_uses_generic_gateway_error(monkeypatch):
+    from app.routers import erp_login
+
+    original_async_client = httpx.AsyncClient
+
+    def handler(request: httpx.Request) -> httpx.Response:
+        assert request.url.path == "/api/auth/qr-login/sessions/123/preview"
+        return httpx.Response(403, json={"detail": "do-not-leak"})
+
+    transport = httpx.MockTransport(handler)
+
+    def fake_async_client(**kwargs):
+        _ = kwargs
+        return original_async_client(transport=transport)
+
+    monkeypatch.setattr(erp_login.httpx, "AsyncClient", fake_async_client)
+    client = _client(monkeypatch)
+
+    response = client.get("/api/erp-login/sessions/ticket-abc?session_id=123")
+
+    assert response.status_code == 502
+    assert response.json()["detail"] == "ERP扫码登录服务暂时不可用"
+
+
 def test_create_device_qrcode_delegates_to_miniapp_qrcode_directory(monkeypatch):
     calls = []