feat: add new llm client for deepseek [LET-4056] (#4219)

feat: add new llm client for deepseek

letta/llm_api/deepseek_client.py

@@ -0,0 +1,97 @@
+import os
+from typing import List, Optional
+
+from openai import AsyncOpenAI, AsyncStream, OpenAI
+from openai.types.chat.chat_completion import ChatCompletion
+from openai.types.chat.chat_completion_chunk import ChatCompletionChunk
+
+from letta.llm_api.deepseek import convert_deepseek_response_to_chatcompletion, map_messages_to_deepseek_format
+from letta.llm_api.openai_client import OpenAIClient
+from letta.otel.tracing import trace_method
+from letta.schemas.llm_config import LLMConfig
+from letta.schemas.message import Message as PydanticMessage
+from letta.schemas.openai.chat_completion_response import ChatCompletionResponse
+from letta.settings import model_settings
+
+
+class DeepseekClient(OpenAIClient):
+
+    def requires_auto_tool_choice(self, llm_config: LLMConfig) -> bool:
+        return False
+
+    def supports_structured_output(self, llm_config: LLMConfig) -> bool:
+        return False
+
+    @trace_method
+    def build_request_data(
+        self,
+        messages: List[PydanticMessage],
+        llm_config: LLMConfig,
+        tools: Optional[List[dict]] = None,
+        force_tool_call: Optional[str] = None,
+    ) -> dict:
+        # Override put_inner_thoughts_in_kwargs to False for DeepSeek
+        llm_config.put_inner_thoughts_in_kwargs = False
+
+        data = super().build_request_data(messages, llm_config, tools, force_tool_call)
+
+        def add_functions_to_system_message(system_message: ChatMessage):
+            system_message.content += f"<available functions> {''.join(json.dumps(f) for f in functions)} </available functions>"
+            system_message.content += 'Select best function to call simply respond with a single json block with the fields "name" and "arguments". Use double quotes around the arguments.'
+
+        if llm_config.model == "deepseek-reasoner":  # R1 currently doesn't support function calling natively
+            add_functions_to_system_message(
+                data["messages"][0]
+            )  # Inject additional instructions to the system prompt with the available functions
+
+            data["messages"] = map_messages_to_deepseek_format(data["messages"])
+
+        return data
+
+    @trace_method
+    def request(self, request_data: dict, llm_config: LLMConfig) -> dict:
+        """
+        Performs underlying synchronous request to OpenAI API and returns raw response dict.
+        """
+        api_key = model_settings.deepseek_api_key or os.environ.get("DEEPSEEK_API_KEY")
+        client = OpenAI(api_key=api_key, base_url=llm_config.model_endpoint)
+
+        response: ChatCompletion = client.chat.completions.create(**request_data)
+        return response.model_dump()
+
+    @trace_method
+    async def request_async(self, request_data: dict, llm_config: LLMConfig) -> dict:
+        """
+        Performs underlying asynchronous request to OpenAI API and returns raw response dict.
+        """
+        api_key = model_settings.deepseek_api_key or os.environ.get("DEEPSEEK_API_KEY")
+        client = AsyncOpenAI(api_key=api_key, base_url=llm_config.model_endpoint)
+
+        response: ChatCompletion = await client.chat.completions.create(**request_data)
+        return response.model_dump()
+
+    @trace_method
+    async def stream_async(self, request_data: dict, llm_config: LLMConfig) -> AsyncStream[ChatCompletionChunk]:
+        """
+        Performs underlying asynchronous streaming request to OpenAI and returns the async stream iterator.
+        """
+        api_key = model_settings.deepseek_api_key or os.environ.get("DEEPSEEK_API_KEY")
+        client = AsyncOpenAI(api_key=api_key, base_url=llm_config.model_endpoint)
+        response_stream: AsyncStream[ChatCompletionChunk] = await client.chat.completions.create(
+            **request_data, stream=True, stream_options={"include_usage": True}
+        )
+        return response_stream
+
+    @trace_method
+    def convert_response_to_chat_completion(
+        self,
+        response_data: dict,
+        input_messages: List[PydanticMessage],  # Included for consistency, maybe used later
+        llm_config: LLMConfig,
+    ) -> ChatCompletionResponse:
+        """
+        Converts raw OpenAI response dict into the ChatCompletionResponse Pydantic model.
+        Handles potential extraction of inner thoughts if they were added via kwargs.
+        """
+        response = ChatCompletionResponse(**response_data)
+        return convert_deepseek_response_to_chatcompletion(response)

letta/llm_api/llm_client.py

@@ -93,5 +93,12 @@ class LLMClient:
                     put_inner_thoughts_first=put_inner_thoughts_first,
                     actor=actor,
                 )
+            case ProviderType.deepseek:
+                from letta.llm_api.deepseek_client import DeepseekClient
+
+                return DeepseekClient(
+                    put_inner_thoughts_first=put_inner_thoughts_first,
+                    actor=actor,
+                )
             case _:
                 return None