feat: Implement OpenAI-compatible tool calling by injecting tool prompts and parsing tool calls from model responses.

tests/test_unit.py

@@ -451,6 +451,112 @@ class TestStreamParsing(unittest.TestCase):
         self.assertTrue(check_response_started(response_fragment))  # RESPONSE 触发
 
 
+class TestToolCallParsing(unittest.TestCase):
+    """工具调用解析测试"""
+
+    def test_parse_tool_calls_simple(self):
+        """测试简单工具调用解析"""
+        from core.sse_parser import parse_tool_calls
+        
+        response_text = '{"tool_calls": [{"name": "get_weather", "input": {"location": "Beijing"}}]}'
+        tools = [{"name": "get_weather"}]
+        
+        result = parse_tool_calls(response_text, tools)
+        
+        self.assertEqual(len(result), 1)
+        self.assertEqual(result[0]["name"], "get_weather")
+        self.assertEqual(result[0]["input"]["location"], "Beijing")
+
+    def test_parse_tool_calls_multiple(self):
+        """测试多工具调用解析"""
+        from core.sse_parser import parse_tool_calls
+        
+        response_text = '''{"tool_calls": [
+            {"name": "get_weather", "input": {"location": "Beijing"}},
+            {"name": "get_time", "input": {"timezone": "Asia/Shanghai"}}
+        ]}'''
+        tools = [{"name": "get_weather"}, {"name": "get_time"}]
+        
+        result = parse_tool_calls(response_text, tools)
+        
+        self.assertEqual(len(result), 2)
+        self.assertEqual(result[0]["name"], "get_weather")
+        self.assertEqual(result[1]["name"], "get_time")
+
+    def test_parse_tool_calls_no_match(self):
+        """测试无工具调用时返回空列表"""
+        from core.sse_parser import parse_tool_calls
+        
+        response_text = "这是一个普通的回复，没有工具调用。"
+        tools = [{"name": "get_weather"}]
+        
+        result = parse_tool_calls(response_text, tools)
+        
+        self.assertEqual(result, [])
+
+    def test_parse_tool_calls_with_surrounding_text(self):
+        """测试带有周围文本的工具调用"""
+        from core.sse_parser import parse_tool_calls
+        
+        response_text = '''好的，我来帮你查询天气。
+{"tool_calls": [{"name": "get_weather", "input": {"location": "Shanghai"}}]}'''
+        tools = [{"name": "get_weather"}]
+        
+        result = parse_tool_calls(response_text, tools)
+        
+        self.assertEqual(len(result), 1)
+        self.assertEqual(result[0]["name"], "get_weather")
+
+    def test_parse_tool_calls_empty_input(self):
+        """测试空输入"""
+        from core.sse_parser import parse_tool_calls
+        
+        result = parse_tool_calls("", [])
+        self.assertEqual(result, [])
+        
+        result = parse_tool_calls("some text", [])
+        self.assertEqual(result, [])
+
+    def test_parse_tool_calls_invalid_json(self):
+        """测试无效 JSON"""
+        from core.sse_parser import parse_tool_calls
+        
+        response_text = '{"tool_calls": [{"name": "get_weather", invalid json here}'
+        tools = [{"name": "get_weather"}]
+        
+        result = parse_tool_calls(response_text, tools)
+        
+        # 应该返回空列表而不是抛出异常
+        self.assertEqual(result, [])
+
+
+class TestTokenEstimation(unittest.TestCase):
+    """Token 估算测试"""
+    
+    def test_estimate_tokens_string(self):
+        """测试字符串 token 估算"""
+        from core.utils import estimate_tokens
+        
+        # 8个字符应该约等于2个token
+        result = estimate_tokens("12345678")
+        self.assertEqual(result, 2)
+        
+        # 空字符串应该返回1
+        result = estimate_tokens("")
+        self.assertEqual(result, 1)
+
+    def test_estimate_tokens_list(self):
+        """测试列表 token 估算"""
+        from core.utils import estimate_tokens
+        
+        content = [
+            {"text": "Hello"},
+            {"text": "World"}
+        ]
+        result = estimate_tokens(content)
+        self.assertGreater(result, 0)
+
+
 if __name__ == "__main__":
     # 设置环境变量避免配置警告
     os.environ.setdefault("DS2API_CONFIG_PATH",