feat: keep the gateway's words on the OCR branches too

Issue #10 Task 4: the OCR side said only 'HTTP 404'. The issue reported
the chat path, but the batch that lost its 400 was reading tables - the
same blind spot, one transport over. Reuses the shared summarizer.

tests/unit/test_monkey_ocr.py

@@ -19,7 +19,11 @@ from polygateway.errors import (
     SourceDeadError,
     TransientError,
 )
-from polygateway.transports.monkey_ocr import MonkeyOcrTransport, _parse_middle_json
+from polygateway.transports.monkey_ocr import (
+    MonkeyOcrTransport,
+    _classify_status,
+    _parse_middle_json,
+)
 from polygateway.types import SourceConfig
 
 
@@ -306,6 +310,40 @@ class TestErrorTranslation:
             await t.recognize_text(image=b"jpg", source=_source(), call_id="c1")
         assert ei.value.status_code == status
 
+    @pytest.mark.parametrize(
+        ("status", "exc_type"),
+        [(502, TransientError), (401, SourceDeadError), (404, RequestRejectedError)],
+    )
+    async def test_body_survives_every_branch(self, status, exc_type):
+        """issue #10: OCR 侧 message 原本只有 HTTP 状态码,拒绝理由同样丢失。"""
+        body = '{"detail":"unsupported image mode CMYK"}'
+        t = _transport_for(_routes(text_resp=httpx.Response(status, content=body.encode())))
+        with pytest.raises(exc_type) as ei:
+            await t.recognize_text(image=b"jpg", source=_source(), call_id="c1")
+        assert ei.value.body_text == body
+        assert str(ei.value).endswith(f" | {body}")
+
+    def test_unread_body_degrades_without_changing_class(self):
+        """取不到 body 时降级空串: 绝不能让 ResponseNotRead 逃出错误四分类。
+
+        直接测纯函数而非走 MockTransport——真实客户端对非 stream 请求总会读完
+        响应,未读态只可能在将来给 OCR 加 stream 时出现,而那正是要防的场景。
+        """
+
+        class _Unread(httpx.SyncByteStream):
+            def __iter__(self):
+                yield b"body"
+
+        exc = httpx.HTTPStatusError(
+            "404",
+            request=httpx.Request("POST", "http://ocr.example/ocr/text"),
+            response=httpx.Response(404, stream=_Unread()),
+        )
+        err = _classify_status(exc, "monkey_1", "text")
+        assert isinstance(err, RequestRejectedError)
+        assert err.body_text == ""
+        assert str(err) == "monkey_1 OCR text HTTP 404"
+
     async def test_connect_error_transient(self):
         def handler(request):
             raise httpx.ConnectError("refused", request=request)