diff --git a/src/langbot/pkg/platform/sources/wecomcs.py b/src/langbot/pkg/platform/sources/wecomcs.py
index 9af809f7d..ea7d8ef5c 100644
--- a/src/langbot/pkg/platform/sources/wecomcs.py
+++ b/src/langbot/pkg/platform/sources/wecomcs.py
@@ -2,6 +2,7 @@ from __future__ import annotations
 import typing
 import asyncio
 import traceback
+import uuid
 
 import datetime
 import pydantic
@@ -182,7 +183,28 @@ class WecomCSAdapter(abstract_platform_adapter.AbstractMessagePlatformAdapter):
                 )
 
     async def send_message(self, target_type: str, target_id: str, message: platform_message.MessageChain):
-        pass
+        if target_type != 'person':
+            raise ValueError('WeCom customer service only supports sending messages to person targets')
+
+        open_kfid = self.bot_account_id
+        external_userid = target_id
+        if '|' in target_id:
+            open_kfid, external_userid = target_id.split('|', 1)
+        if external_userid.startswith('u'):
+            external_userid = external_userid[1:]
+        if not open_kfid:
+            raise ValueError('WeCom customer service open_kfid is required before sending messages')
+
+        content_list = await WecomMessageConverter.yiri2target(message, self.bot)
+        for content in content_list:
+            msgid = f'langbot_{uuid.uuid4().hex}'
+            if content['type'] == 'text':
+                await self.bot.send_text_msg(
+                    open_kfid=open_kfid,
+                    external_userid=external_userid,
+                    msgid=msgid,
+                    content=content['content'],
+                )
 
     def set_bot_uuid(self, bot_uuid: str):
         """设置 bot UUID（用于生成 webhook URL）"""
diff --git a/tests/unit_tests/platform/test_wecomcs_adapter.py b/tests/unit_tests/platform/test_wecomcs_adapter.py
new file mode 100644
index 000000000..ee3425b61
--- /dev/null
+++ b/tests/unit_tests/platform/test_wecomcs_adapter.py
@@ -0,0 +1,91 @@
+from types import SimpleNamespace
+from unittest.mock import AsyncMock
+
+import pytest
+
+import langbot_plugin.api.definition.abstract.platform.event_logger as abstract_platform_logger
+import langbot_plugin.api.entities.builtin.platform.message as platform_message
+from langbot.pkg.platform.sources.wecomcs import WecomCSAdapter
+
+
+class DummyLogger(abstract_platform_logger.AbstractEventLogger):
+    async def info(self, *args, **kwargs):
+        pass
+
+    async def debug(self, *args, **kwargs):
+        pass
+
+    async def warning(self, *args, **kwargs):
+        pass
+
+    async def error(self, *args, **kwargs):
+        pass
+
+
+def make_adapter():
+    return WecomCSAdapter(
+        config={
+            'corpid': 'corp-id',
+            'secret': 'secret',
+            'token': 'token',
+            'EncodingAESKey': 'encoding-key',
+        },
+        logger=DummyLogger(),
+    )
+
+
+@pytest.mark.asyncio
+async def test_send_message_sends_text_to_customer_service_user():
+    adapter = make_adapter()
+    adapter.bot_account_id = 'kf-test'
+    adapter.bot = SimpleNamespace(send_text_msg=AsyncMock())
+
+    message = platform_message.MessageChain([platform_message.Plain(text='hello')])
+
+    await adapter.send_message('person', 'uexternal-user', message)
+
+    adapter.bot.send_text_msg.assert_awaited_once()
+    kwargs = adapter.bot.send_text_msg.await_args.kwargs
+    assert kwargs['open_kfid'] == 'kf-test'
+    assert kwargs['external_userid'] == 'external-user'
+    assert kwargs['content'] == 'hello'
+    assert kwargs['msgid'].startswith('langbot_')
+
+
+@pytest.mark.asyncio
+async def test_send_message_allows_explicit_open_kfid_in_target_id():
+    adapter = make_adapter()
+    adapter.bot = SimpleNamespace(send_text_msg=AsyncMock())
+
+    message = platform_message.MessageChain([platform_message.Plain(text='hello')])
+
+    await adapter.send_message('person', 'kf-explicit|uexternal-user', message)
+
+    kwargs = adapter.bot.send_text_msg.await_args.kwargs
+    assert kwargs['open_kfid'] == 'kf-explicit'
+    assert kwargs['external_userid'] == 'external-user'
+
+
+@pytest.mark.asyncio
+async def test_send_message_requires_open_kfid():
+    adapter = make_adapter()
+    adapter.bot = SimpleNamespace(send_text_msg=AsyncMock())
+    message = platform_message.MessageChain([platform_message.Plain(text='hello')])
+
+    with pytest.raises(ValueError, match='open_kfid is required'):
+        await adapter.send_message('person', 'uexternal-user', message)
+
+    adapter.bot.send_text_msg.assert_not_called()
+
+
+@pytest.mark.asyncio
+async def test_send_message_rejects_group_targets():
+    adapter = make_adapter()
+    adapter.bot_account_id = 'kf-test'
+    adapter.bot = SimpleNamespace(send_text_msg=AsyncMock())
+    message = platform_message.MessageChain([platform_message.Plain(text='hello')])
+
+    with pytest.raises(ValueError, match='only supports sending messages to person'):
+        await adapter.send_message('group', 'group-id', message)
+
+    adapter.bot.send_text_msg.assert_not_called()