diff --git a/backend/app/channels/feishu.py b/backend/app/channels/feishu.py
index fa9f10ef95..9ba97e233c 100644
--- a/backend/app/channels/feishu.py
+++ b/backend/app/channels/feishu.py
@@ -668,9 +668,7 @@ class FeishuChannel(Channel):
     async def _upload_image(self, path) -> str:
         """Upload an image to Feishu and return the image_key."""
         response = await asyncio.to_thread(self._upload_image_sync, path)
-        if not response.success():
-            raise RuntimeError(f"Feishu image upload failed: code={response.code}, msg={response.msg}")
-        return response.data.image_key
+        return self._uploaded_key(response, "image")
 
     def _upload_file_sync(self, path, filename: str, file_type: str):
         with open(str(path), "rb") as f:
@@ -692,9 +690,17 @@ class FeishuChannel(Channel):
             file_type = "stream"
 
         response = await asyncio.to_thread(self._upload_file_sync, path, filename, file_type)
+        return self._uploaded_key(response, "file")
+
+    @staticmethod
+    def _uploaded_key(response, kind: str) -> str:
+        """Return the ``image_key``/``file_key`` of an upload response or raise with its log_id."""
         if not response.success():
-            raise RuntimeError(f"Feishu file upload failed: code={response.code}, msg={response.msg}")
-        return response.data.file_key
+            raise RuntimeError(f"Feishu {kind} upload failed: code={response.code}, msg={response.msg}, log_id={response.get_log_id()}")
+        key = getattr(getattr(response, "data", None), f"{kind}_key", None)
+        if not isinstance(key, str) or not key:
+            raise RuntimeError(f"Feishu {kind} upload returned no {kind}_key: log_id={response.get_log_id()}")
+        return key
 
     async def receive_file(self, msg: InboundMessage, thread_id: str, *, user_id: str | None = None) -> InboundMessage:
         """Download a Feishu file into the thread uploads directory.
diff --git a/backend/tests/test_feishu_upload_key_checks.py b/backend/tests/test_feishu_upload_key_checks.py
new file mode 100644
index 0000000000..057c5a53ed
--- /dev/null
+++ b/backend/tests/test_feishu_upload_key_checks.py
@@ -0,0 +1,89 @@
+"""Feishu image/file uploads must fail with a diagnosable error.
+
+``_upload_image``/``_upload_file`` used to read ``response.data.image_key`` /
+``response.data.file_key`` straight after ``success()``. A success response
+without ``data`` surfaced as a bare ``AttributeError``, an empty key was handed
+on to ``message.reply``/``message.create`` as ``{"image_key": ""}``, and the
+business-failure error omitted the ``log_id`` that every other Feishu API error
+in the channel carries.
+"""
+
+from __future__ import annotations
+
+import asyncio
+from types import SimpleNamespace
+from unittest.mock import MagicMock
+
+import pytest
+
+from app.channels.feishu import FeishuChannel
+from app.channels.message_bus import MessageBus
+
+
+def _channel() -> FeishuChannel:
+    channel = FeishuChannel(MessageBus(), config={})
+    channel._api_client = MagicMock()
+    return channel
+
+
+def _response(*, success: bool, data=None, log_id: str = "log-upload-1"):
+    response = MagicMock()
+    response.success.return_value = success
+    response.code = 0 if success else 99991400
+    response.msg = "ok" if success else "param invalid"
+    response.data = data
+    response.get_log_id.return_value = log_id
+    return response
+
+
+def _upload(channel: FeishuChannel, kind: str, tmp_path):
+    path = tmp_path / ("image.png" if kind == "image" else "report.pdf")
+    path.write_bytes(b"data")
+    if kind == "image":
+        return asyncio.run(channel._upload_image(path))
+    return asyncio.run(channel._upload_file(path, path.name))
+
+
+def _patch_sync_upload(channel: FeishuChannel, kind: str, response) -> None:
+    if kind == "image":
+        channel._upload_image_sync = MagicMock(return_value=response)
+    else:
+        channel._upload_file_sync = MagicMock(return_value=response)
+
+
+@pytest.mark.parametrize("kind", ["image", "file"])
+def test_upload_business_failure_includes_log_id(kind, tmp_path):
+    channel = _channel()
+    _patch_sync_upload(channel, kind, _response(success=False, log_id="log-upload-fail"))
+
+    with pytest.raises(RuntimeError, match="log_id=log-upload-fail"):
+        _upload(channel, kind, tmp_path)
+
+
+@pytest.mark.parametrize("kind", ["image", "file"])
+@pytest.mark.parametrize(
+    "data",
+    [
+        None,
+        SimpleNamespace(image_key=None, file_key=None),
+        SimpleNamespace(image_key="", file_key=""),
+        SimpleNamespace(image_key=123, file_key=456),
+    ],
+    ids=["no-data", "none-key", "empty-key", "non-str-key"],
+)
+def test_upload_success_without_key_raises_runtime_error(kind, data, tmp_path):
+    channel = _channel()
+    _patch_sync_upload(channel, kind, _response(success=True, data=data, log_id="log-no-key"))
+
+    with pytest.raises(RuntimeError, match=f"no {kind}_key.*log_id=log-no-key"):
+        _upload(channel, kind, tmp_path)
+
+
+@pytest.mark.parametrize("kind", ["image", "file"])
+def test_upload_success_returns_key(kind, tmp_path):
+    channel = _channel()
+    data = SimpleNamespace(image_key="img-key-1", file_key="file-key-1")
+    _patch_sync_upload(channel, kind, _response(success=True, data=data))
+
+    expected = "img-key-1" if kind == "image" else "file-key-1"
+    assert _upload(channel, kind, tmp_path) == expected