diff --git a/tests/test_client_info.py b/tests/test_client_info.py
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+++ b/tests/test_client_info.py
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+"""
+Tests for utils/client_info.py
+
+测试 utils/client_info.py 模块的功能。
+
+这个模块的作用是：识别连接到 MCP 服务器的客户端是谁（Claude、Gemini、Cursor 等），
+并提供友好的名称显示。
+"""
+
+from unittest.mock import MagicMock
+
+import pytest
+
+import utils.client_info as client_info_module
+from utils.client_info import (
+    CLIENT_NAME_MAPPINGS,
+    DEFAULT_FRIENDLY_NAME,
+    format_client_info,
+    get_cached_client_info,
+    get_client_friendly_name,
+    get_client_info_from_context,
+    get_friendly_name,
+    log_client_info,
+)
+
+
+@pytest.fixture(autouse=True)
+def reset_client_info_cache(monkeypatch):
+    """
+    每个测试运行前自动重置客户端信息缓存。
+
+    使用 monkeypatch 而不是直接修改私有变量，这样更符合测试最佳实践。
+    """
+    monkeypatch.setattr(client_info_module, "_client_info_cache", None)
+
+
+class TestGetFriendlyName:
+    """测试 get_friendly_name() 函数"""
+
+    def test_empty_string_returns_default(self):
+        """传入空字符串时，应该返回默认名称"""
+        assert get_friendly_name("") == DEFAULT_FRIENDLY_NAME
+
+    def test_none_returns_default(self):
+        """传入 None 时，应该返回默认名称"""
+        assert get_friendly_name(None) == DEFAULT_FRIENDLY_NAME
+
+    @pytest.mark.parametrize(
+        "client_name",
+        [
+            "claude-ai",
+            "Claude-AI",
+            "CLAUDE-AI",
+            "claude",
+            "claude-desktop",
+            "claude-code",
+            "anthropic",
+        ],
+    )
+    def test_claude_variants(self, client_name):
+        """各种 Claude 客户端名称都应该识别为 'Claude'"""
+        assert get_friendly_name(client_name) == "Claude"
+
+    @pytest.mark.parametrize(
+        "client_name",
+        [
+            "gemini-cli-mcp-client",
+            "gemini-cli",
+            "gemini",
+            "google",
+        ],
+    )
+    def test_gemini_variants(self, client_name):
+        """各种 Gemini 客户端名称都应该识别为 'Gemini'"""
+        assert get_friendly_name(client_name) == "Gemini"
+
+    @pytest.mark.parametrize(
+        ("client_name", "expected"),
+        [
+            ("cursor", "Cursor"),
+            ("vscode", "VS Code"),
+            ("codeium", "Codeium"),
+            ("copilot", "GitHub Copilot"),
+            ("mcp-client", "MCP Client"),
+            ("test-client", "Test Client"),
+        ],
+    )
+    def test_other_known_clients(self, client_name, expected):
+        """其他已知客户端应该正确识别"""
+        assert get_friendly_name(client_name) == expected
+
+    @pytest.mark.parametrize(
+        "client_name",
+        [
+            "unknown-client",
+            "random-app",
+            "my-custom-tool",
+        ],
+    )
+    def test_unknown_client_returns_default(self, client_name):
+        """未知的客户端名称应该返回默认值"""
+        assert get_friendly_name(client_name) == DEFAULT_FRIENDLY_NAME
+
+    @pytest.mark.parametrize(
+        ("client_name", "expected"),
+        [
+            ("CLAUDE", "Claude"),
+            ("GEMINI", "Gemini"),
+            ("CuRsOr", "Cursor"),
+        ],
+    )
+    def test_case_insensitive_matching(self, client_name, expected):
+        """名称匹配应该不区分大小写"""
+        assert get_friendly_name(client_name) == expected
+
+    @pytest.mark.parametrize(
+        ("client_name", "expected"),
+        [
+            ("my-claude-extension", "Claude"),
+            ("gemini-custom-build", "Gemini"),
+        ],
+    )
+    def test_partial_matching(self, client_name, expected):
+        """部分匹配应该能工作"""
+        assert get_friendly_name(client_name) == expected
+
+
+class TestFormatClientInfo:
+    """测试 format_client_info() 函数"""
+
+    def test_none_returns_default(self):
+        """传入 None 时，应该返回默认名称"""
+        assert format_client_info(None) == DEFAULT_FRIENDLY_NAME
+
+    def test_empty_dict_returns_default(self):
+        """传入空字典时，应该返回默认名称"""
+        assert format_client_info({}) == DEFAULT_FRIENDLY_NAME
+
+    def test_with_friendly_name(self):
+        """使用友好名称模式时，应该返回友好名称"""
+        client_info = {
+            "name": "claude-ai",
+            "version": "1.0.0",
+            "friendly_name": "Claude",
+        }
+        assert format_client_info(client_info, use_friendly_name=True) == "Claude"
+
+    def test_without_friendly_name_flag(self):
+        """不使用友好名称模式时，应该返回原始名称和版本号"""
+        client_info = {
+            "name": "claude-ai",
+            "version": "1.0.0",
+            "friendly_name": "Claude",
+        }
+        assert format_client_info(client_info, use_friendly_name=False) == "claude-ai v1.0.0"
+
+    def test_without_version(self):
+        """没有版本号时，应该只返回名称"""
+        client_info = {"name": "claude-ai", "friendly_name": "Claude"}
+        assert format_client_info(client_info, use_friendly_name=True) == "Claude"
+        assert format_client_info(client_info, use_friendly_name=False) == "claude-ai"
+
+    def test_fallback_to_name_when_no_friendly_name(self):
+        """如果没有 friendly_name 字段，应该回退到使用 name 字段"""
+        client_info = {"name": "custom-client"}
+        assert format_client_info(client_info, use_friendly_name=True) == "custom-client"
+
+
+class TestGetClientInfoFromContext:
+    """测试 get_client_info_from_context() 函数"""
+
+    def test_none_server_returns_none(self):
+        """传入 None 服务器时，应该返回 None"""
+        assert get_client_info_from_context(None) is None
+
+    def test_server_without_request_context(self):
+        """服务器没有 request_context 属性时，应该返回 None"""
+        server = MagicMock(spec=[])
+        assert get_client_info_from_context(server) is None
+
+    def test_server_with_none_request_context(self):
+        """服务器的 request_context 是 None 时，应该返回 None"""
+        server = MagicMock()
+        server.request_context = None
+        assert get_client_info_from_context(server) is None
+
+    def test_client_params_without_client_info(self):
+        """_client_params 存在但没有 clientInfo 属性时，应该返回 None"""
+        server = MagicMock()
+        server.request_context.session._client_params = MagicMock(spec=[])
+        assert get_client_info_from_context(server) is None
+
+    def test_successful_extraction(self):
+        """成功从有效的服务器上下文中提取客户端信息"""
+        server = MagicMock()
+        server.request_context.session._client_params.clientInfo.name = "claude-ai"
+        server.request_context.session._client_params.clientInfo.version = "1.0.0"
+
+        result = get_client_info_from_context(server)
+
+        assert result is not None
+        assert result["name"] == "claude-ai"
+        assert result["version"] == "1.0.0"
+        assert result["friendly_name"] == "Claude"
+
+    def test_caching_behavior(self):
+        """缓存机制是否正常工作"""
+        # 第一次调用
+        server1 = MagicMock()
+        server1.request_context.session._client_params.clientInfo.name = "gemini-cli"
+        server1.request_context.session._client_params.clientInfo.version = "2.0.0"
+
+        result1 = get_client_info_from_context(server1)
+        assert result1["name"] == "gemini-cli"
+
+        # 第二次调用应该返回缓存的结果
+        server2 = MagicMock()
+        server2.request_context.session._client_params.clientInfo.name = "different-client"
+
+        result2 = get_client_info_from_context(server2)
+        assert result2["name"] == "gemini-cli"  # 仍然是缓存的值
+
+    def test_extraction_with_missing_version(self):
+        """客户端信息缺少 version 字段时，应该能正常处理"""
+        server = MagicMock()
+        client_info_mock = MagicMock(spec=["name"])
+        client_info_mock.name = "test-client"
+        server.request_context.session._client_params.clientInfo = client_info_mock
+
+        result = get_client_info_from_context(server)
+
+        assert result is not None
+        assert result["name"] == "test-client"
+        assert "version" not in result
+
+
+class TestGetCachedClientInfo:
+    """测试 get_cached_client_info() 函数"""
+
+    def test_returns_none_when_not_cached(self):
+        """没有缓存时，应该返回 None"""
+        assert get_cached_client_info() is None
+
+    def test_returns_cached_value(self, monkeypatch):
+        """有缓存时，应该返回缓存的值"""
+        test_info = {"name": "test", "friendly_name": "Test"}
+        monkeypatch.setattr(client_info_module, "_client_info_cache", test_info)
+
+        assert get_cached_client_info() == test_info
+
+
+class TestGetClientFriendlyName:
+    """测试 get_client_friendly_name() 函数"""
+
+    def test_returns_default_when_not_cached(self):
+        """没有缓存时，应该返回默认名称"""
+        assert get_client_friendly_name() == DEFAULT_FRIENDLY_NAME
+
+    def test_returns_friendly_name_from_cache(self, monkeypatch):
+        """有缓存时，应该返回缓存中的友好名称"""
+        monkeypatch.setattr(
+            client_info_module,
+            "_client_info_cache",
+            {"name": "gemini-cli", "friendly_name": "Gemini"},
+        )
+
+        assert get_client_friendly_name() == "Gemini"
+
+    def test_returns_default_when_friendly_name_missing(self, monkeypatch):
+        """缓存中没有 friendly_name 字段时，应该返回默认名称"""
+        monkeypatch.setattr(client_info_module, "_client_info_cache", {"name": "some-client"})
+
+        assert get_client_friendly_name() == DEFAULT_FRIENDLY_NAME
+
+
+class TestLogClientInfo:
+    """测试 log_client_info() 函数"""
+
+    def test_logs_client_info_when_available(self):
+        """成功提取客户端信息时，应该记录 info 级别的日志"""
+        server = MagicMock()
+        server.request_context.session._client_params.clientInfo.name = "claude-ai"
+        server.request_context.session._client_params.clientInfo.version = "1.0.0"
+
+        mock_logger = MagicMock()
+        log_client_info(server, logger_instance=mock_logger)
+
+        mock_logger.info.assert_called()
+        call_args = mock_logger.info.call_args[0][0]
+        assert "Claude" in call_args
+
+    def test_logs_debug_when_not_available(self):
+        """无法提取客户端信息时，应该记录 debug 级别的日志"""
+        mock_logger = MagicMock()
+        log_client_info(None, logger_instance=mock_logger)
+
+        mock_logger.debug.assert_called_with("Could not extract client info from MCP protocol")
+
+
+class TestClientNameMappings:
+    """测试 CLIENT_NAME_MAPPINGS 常量"""
+
+    def test_mappings_not_empty(self):
+        """映射字典不应该为空"""
+        assert len(CLIENT_NAME_MAPPINGS) > 0
+
+    def test_all_mappings_have_string_values(self):
+        """所有的键和值都应该是字符串"""
+        for key, value in CLIENT_NAME_MAPPINGS.items():
+            assert isinstance(key, str)
+            assert isinstance(value, str)
+
+    def test_default_friendly_name_is_string(self):
+        """默认友好名称应该是非空字符串"""
+        assert isinstance(DEFAULT_FRIENDLY_NAME, str)
+        assert len(DEFAULT_FRIENDLY_NAME) > 0