Allow passing a system prompt (#1318)

fern/openapi/openapi.json

@@ -23,7 +23,7 @@
           "Contextual Completions"
         ],
         "summary": "Completion",
-          "description": "We recommend most users use our Chat completions API.\n\nGiven a prompt, the model will return one predicted completion. If `use_context`\nis set to `true`, the model will use context coming from the ingested documents\nto create the response. The documents being used can be filtered using the\n`context_filter` and passing the document IDs to be used. Ingested documents IDs\ncan be found using `/ingest/list` endpoint. If you want all ingested documents to\nbe used, remove `context_filter` altogether.\n\nWhen using `'include_sources': true`, the API will return the source Chunks used\nto create the response, which come from the context provided.\n\nWhen using `'stream': true`, the API will return data chunks following [OpenAI's\nstreaming model](https://platform.openai.com/docs/api-reference/chat/streaming):\n```\n{\"id\":\"12345\",\"object\":\"completion.chunk\",\"created\":1694268190,\n\"model\":\"private-gpt\",\"choices\":[{\"index\":0,\"delta\":{\"content\":\"Hello\"},\n\"finish_reason\":null}]}\n```",
+        "description": "We recommend most users use our Chat completions API.\n\nGiven a prompt, the model will return one predicted completion.\n\nOptionally include a `system_prompt` to influence the way the LLM answers.\n\nIf `use_context`\nis set to `true`, the model will use context coming from the ingested documents\nto create the response. The documents being used can be filtered using the\n`context_filter` and passing the document IDs to be used. Ingested documents IDs\ncan be found using `/ingest/list` endpoint. If you want all ingested documents to\nbe used, remove `context_filter` altogether.\n\nWhen using `'include_sources': true`, the API will return the source Chunks used\nto create the response, which come from the context provided.\n\nWhen using `'stream': true`, the API will return data chunks following [OpenAI's\nstreaming model](https://platform.openai.com/docs/api-reference/chat/streaming):\n```\n{\"id\":\"12345\",\"object\":\"completion.chunk\",\"created\":1694268190,\n\"model\":\"private-gpt\",\"choices\":[{\"index\":0,\"delta\":{\"content\":\"Hello\"},\n\"finish_reason\":null}]}\n```",
         "operationId": "prompt_completion_v1_completions_post",
         "requestBody": {
           "content": {
@@ -65,7 +65,7 @@
           "Contextual Completions"
         ],
         "summary": "Chat Completion",
-          "description": "Given a list of messages comprising a conversation, return a response.\n\nIf `use_context` is set to `true`, the model will use context coming\nfrom the ingested documents to create the response. The documents being used can\nbe filtered using the `context_filter` and passing the document IDs to be used.\nIngested documents IDs can be found using `/ingest/list` endpoint. If you want\nall ingested documents to be used, remove `context_filter` altogether.\n\nWhen using `'include_sources': true`, the API will return the source Chunks used\nto create the response, which come from the context provided.\n\nWhen using `'stream': true`, the API will return data chunks following [OpenAI's\nstreaming model](https://platform.openai.com/docs/api-reference/chat/streaming):\n```\n{\"id\":\"12345\",\"object\":\"completion.chunk\",\"created\":1694268190,\n\"model\":\"private-gpt\",\"choices\":[{\"index\":0,\"delta\":{\"content\":\"Hello\"},\n\"finish_reason\":null}]}\n```",
+        "description": "Given a list of messages comprising a conversation, return a response.\n\nOptionally include a `system_prompt` to influence the way the LLM answers.\n\nIf `use_context` is set to `true`, the model will use context coming\nfrom the ingested documents to create the response. The documents being used can\nbe filtered using the `context_filter` and passing the document IDs to be used.\nIngested documents IDs can be found using `/ingest/list` endpoint. If you want\nall ingested documents to be used, remove `context_filter` altogether.\n\nWhen using `'include_sources': true`, the API will return the source Chunks used\nto create the response, which come from the context provided.\n\nWhen using `'stream': true`, the API will return data chunks following [OpenAI's\nstreaming model](https://platform.openai.com/docs/api-reference/chat/streaming):\n```\n{\"id\":\"12345\",\"object\":\"completion.chunk\",\"created\":1694268190,\n\"model\":\"private-gpt\",\"choices\":[{\"index\":0,\"delta\":{\"content\":\"Hello\"},\n\"finish_reason\":null}]}\n```",
         "operationId": "chat_completion_v1_chat_completions_post",
         "requestBody": {
           "content": {
@@ -338,6 +338,17 @@
             "type": "array",
             "title": "Messages"
           },
+          "system_prompt": {
+            "anyOf": [
+              {
+                "type": "string"
+              },
+              {
+                "type": "null"
+              }
+            ],
+            "title": "System Prompt"
+          },
           "use_context": {
             "type": "boolean",
             "title": "Use Context",
@@ -384,6 +395,7 @@
               }
             ],
             "stream": false,
+            "system_prompt": "You are a rapper. Always answer with a rap.",
             "use_context": true
           }
         ]
@@ -391,10 +403,7 @@
       "Chunk": {
         "properties": {
           "object": {
-              "type": "string",
+            "const": "context.chunk",
-              "enum": [
-                "context.chunk"
-              ],
             "title": "Object"
           },
           "score": {
@@ -506,17 +515,11 @@
       "ChunksResponse": {
         "properties": {
           "object": {
-              "type": "string",
+            "const": "list",
-              "enum": [
-                "list"
-              ],
             "title": "Object"
           },
           "model": {
-              "type": "string",
+            "const": "private-gpt",
-              "enum": [
-                "private-gpt"
-              ],
             "title": "Model"
           },
           "data": {
@@ -541,6 +544,17 @@
             "type": "string",
             "title": "Prompt"
           },
+          "system_prompt": {
+            "anyOf": [
+              {
+                "type": "string"
+              },
+              {
+                "type": "null"
+              }
+            ],
+            "title": "System Prompt"
+          },
           "use_context": {
             "type": "boolean",
             "title": "Use Context",
@@ -616,10 +630,7 @@
             "title": "Index"
           },
           "object": {
-              "type": "string",
+            "const": "embedding",
-              "enum": [
-                "embedding"
-              ],
             "title": "Object"
           },
           "embedding": {
@@ -670,17 +681,11 @@
       "EmbeddingsResponse": {
         "properties": {
           "object": {
-              "type": "string",
+            "const": "list",
-              "enum": [
-                "list"
-              ],
             "title": "Object"
           },
           "model": {
-              "type": "string",
+            "const": "private-gpt",
-              "enum": [
-                "private-gpt"
-              ],
             "title": "Model"
           },
           "data": {
@@ -715,33 +720,22 @@
       "HealthResponse": {
         "properties": {
           "status": {
-              "type": "string",
+            "const": "ok",
-              "enum": [
+            "title": "Status",
-                "ok"
+            "default": "ok"
-              ],
-              "title": "Status"
           }
         },
         "type": "object",
-          "required": [
-            "status"
-          ],
         "title": "HealthResponse"
       },
       "IngestResponse": {
         "properties": {
           "object": {
-              "type": "string",
+            "const": "list",
-              "enum": [
-                "list"
-              ],
             "title": "Object"
           },
           "model": {
-              "type": "string",
+            "const": "private-gpt",
-              "enum": [
-                "private-gpt"
-              ],
             "title": "Model"
           },
           "data": {
@@ -763,10 +757,7 @@
       "IngestedDoc": {
         "properties": {
           "object": {
-              "type": "string",
+            "const": "ingest.document",
-              "enum": [
-                "ingest.document"
-              ],
             "title": "Object"
           },
           "doc_id": {
@@ -888,10 +879,7 @@
             ]
           },
           "model": {
-              "type": "string",
+            "const": "private-gpt",
-              "enum": [
-                "private-gpt"
-              ],
             "title": "Model"
           },
           "choices": {
@@ -1021,4 +1009,4 @@
       "description": "Simple health API to make sure the server is up and running."
     }
   ]
-  }
+}

private_gpt/server/chat/chat_router.py

@@ -28,10 +28,14 @@ class ChatBody(BaseModel):
             "examples": [
                 {
                     "messages": [
+                        {
+                            "role": "system",
+                            "content": "You are a rapper. Always answer with a rap.",
+                        },
                         {
                             "role": "user",
                             "content": "How do you fry an egg?",
-                        }
+                        },
                     ],
                     "stream": False,
                     "use_context": True,
@@ -56,6 +60,9 @@ def chat_completion(
 ) -> OpenAICompletion | StreamingResponse:
     """Given a list of messages comprising a conversation, return a response.
 
+    Optionally include an initial `role: system` message to influence the way
+    the LLM answers.
+
     If `use_context` is set to `true`, the model will use context coming
     from the ingested documents to create the response. The documents being used can
     be filtered using the `context_filter` and passing the document IDs to be used.
@@ -79,7 +86,9 @@ def chat_completion(
     ]
     if body.stream:
         completion_gen = service.stream_chat(
-            all_messages, body.use_context, body.context_filter
+            messages=all_messages,
+            use_context=body.use_context,
+            context_filter=body.context_filter,
         )
         return StreamingResponse(
             to_openai_sse_stream(
@@ -89,7 +98,11 @@ def chat_completion(
             media_type="text/event-stream",
         )
     else:
-        completion = service.chat(all_messages, body.use_context, body.context_filter)
+        completion = service.chat(
+            messages=all_messages,
+            use_context=body.use_context,
+            context_filter=body.context_filter,
+        )
         return to_openai_response(
             completion.response, completion.sources if body.include_sources else None
         )

private_gpt/server/chat/chat_service.py

@@ -1,12 +1,13 @@
+from dataclasses import dataclass
+
 from injector import inject, singleton
 from llama_index import ServiceContext, StorageContext, VectorStoreIndex
-from llama_index.chat_engine import ContextChatEngine
+from llama_index.chat_engine import ContextChatEngine, SimpleChatEngine
 from llama_index.chat_engine.types import (
     BaseChatEngine,
 )
 from llama_index.indices.postprocessor import MetadataReplacementPostProcessor
-from llama_index.llm_predictor.utils import stream_chat_response_to_tokens
+from llama_index.llms import ChatMessage, MessageRole
-from llama_index.llms import ChatMessage
 from llama_index.types import TokenGen
 from pydantic import BaseModel
 
@@ -30,6 +31,40 @@ class CompletionGen(BaseModel):
     sources: list[Chunk] | None = None
 
 
+@dataclass
+class ChatEngineInput:
+    system_message: ChatMessage | None = None
+    last_message: ChatMessage | None = None
+    chat_history: list[ChatMessage] | None = None
+
+    @classmethod
+    def from_messages(cls, messages: list[ChatMessage]) -> "ChatEngineInput":
+        # Detect if there is a system message, extract the last message and chat history
+        system_message = (
+            messages[0]
+            if len(messages) > 0 and messages[0].role == MessageRole.SYSTEM
+            else None
+        )
+        last_message = (
+            messages[-1]
+            if len(messages) > 0 and messages[-1].role == MessageRole.USER
+            else None
+        )
+        # Remove from messages list the system message and last message,
+        # if they exist. The rest is the chat history.
+        if system_message:
+            messages.pop(0)
+        if last_message:
+            messages.pop(-1)
+        chat_history = messages if len(messages) > 0 else None
+
+        return cls(
+            system_message=system_message,
+            last_message=last_message,
+            chat_history=chat_history,
+        )
+
+
 @singleton
 class ChatService:
     @inject
@@ -58,18 +93,28 @@ class ChatService:
         )
 
     def _chat_engine(
-        self, context_filter: ContextFilter | None = None
+        self,
+        system_prompt: str | None = None,
+        use_context: bool = False,
+        context_filter: ContextFilter | None = None,
     ) -> BaseChatEngine:
+        if use_context:
             vector_index_retriever = self.vector_store_component.get_retriever(
                 index=self.index, context_filter=context_filter
             )
             return ContextChatEngine.from_defaults(
+                system_prompt=system_prompt,
                 retriever=vector_index_retriever,
                 service_context=self.service_context,
                 node_postprocessors=[
                     MetadataReplacementPostProcessor(target_metadata_key="window"),
                 ],
             )
+        else:
+            return SimpleChatEngine.from_defaults(
+                system_prompt=system_prompt,
+                service_context=self.service_context,
+            )
 
     def stream_chat(
         self,
@@ -77,24 +122,34 @@ class ChatService:
         use_context: bool = False,
         context_filter: ContextFilter | None = None,
     ) -> CompletionGen:
-        if use_context:
+        chat_engine_input = ChatEngineInput.from_messages(messages)
-            last_message = messages[-1].content
+        last_message = (
-            chat_engine = self._chat_engine(context_filter=context_filter)
+            chat_engine_input.last_message.content
+            if chat_engine_input.last_message
+            else None
+        )
+        system_prompt = (
+            chat_engine_input.system_message.content
+            if chat_engine_input.system_message
+            else None
+        )
+        chat_history = (
+            chat_engine_input.chat_history if chat_engine_input.chat_history else None
+        )
+
+        chat_engine = self._chat_engine(
+            system_prompt=system_prompt,
+            use_context=use_context,
+            context_filter=context_filter,
+        )
         streaming_response = chat_engine.stream_chat(
             message=last_message if last_message is not None else "",
-                chat_history=messages[:-1],
+            chat_history=chat_history,
         )
-            sources = [
+        sources = [Chunk.from_node(node) for node in streaming_response.source_nodes]
-                Chunk.from_node(node) for node in streaming_response.source_nodes
-            ]
         completion_gen = CompletionGen(
             response=streaming_response.response_gen, sources=sources
         )
-        else:
-            stream = self.llm_service.llm.stream_chat(messages)
-            completion_gen = CompletionGen(
-                response=stream_chat_response_to_tokens(stream)
-            )
         return completion_gen
 
     def chat(
@@ -103,18 +158,30 @@ class ChatService:
         use_context: bool = False,
         context_filter: ContextFilter | None = None,
     ) -> Completion:
-        if use_context:
+        chat_engine_input = ChatEngineInput.from_messages(messages)
-            last_message = messages[-1].content
+        last_message = (
-            chat_engine = self._chat_engine(context_filter=context_filter)
+            chat_engine_input.last_message.content
+            if chat_engine_input.last_message
+            else None
+        )
+        system_prompt = (
+            chat_engine_input.system_message.content
+            if chat_engine_input.system_message
+            else None
+        )
+        chat_history = (
+            chat_engine_input.chat_history if chat_engine_input.chat_history else None
+        )
+
+        chat_engine = self._chat_engine(
+            system_prompt=system_prompt,
+            use_context=use_context,
+            context_filter=context_filter,
+        )
         wrapped_response = chat_engine.chat(
             message=last_message if last_message is not None else "",
-                chat_history=messages[:-1],
+            chat_history=chat_history,
         )
         sources = [Chunk.from_node(node) for node in wrapped_response.source_nodes]
         completion = Completion(response=wrapped_response.response, sources=sources)
-        else:
-            chat_response = self.llm_service.llm.chat(messages)
-            response_content = chat_response.message.content
-            response = response_content if response_content is not None else ""
-            completion = Completion(response=response)
         return completion

private_gpt/server/completions/completions_router.py

@@ -15,6 +15,7 @@ completions_router = APIRouter(prefix="/v1", dependencies=[Depends(authenticated
 
 class CompletionsBody(BaseModel):
     prompt: str
+    system_prompt: str | None = None
     use_context: bool = False
     context_filter: ContextFilter | None = None
     include_sources: bool = True
@@ -25,6 +26,7 @@ class CompletionsBody(BaseModel):
             "examples": [
                 {
                     "prompt": "How do you fry an egg?",
+                    "system_prompt": "You are a rapper. Always answer with a rap.",
                     "stream": False,
                     "use_context": False,
                     "include_sources": False,
@@ -46,7 +48,11 @@ def prompt_completion(
 ) -> OpenAICompletion | StreamingResponse:
     """We recommend most users use our Chat completions API.
 
-    Given a prompt, the model will return one predicted completion. If `use_context`
+    Given a prompt, the model will return one predicted completion.
+
+    Optionally include a `system_prompt` to influence the way the LLM answers.
+
+    If `use_context`
     is set to `true`, the model will use context coming from the ingested documents
     to create the response. The documents being used can be filtered using the
     `context_filter` and passing the document IDs to be used. Ingested documents IDs
@@ -64,9 +70,13 @@ def prompt_completion(
     "finish_reason":null}]}
     ```
     """
-    message = OpenAIMessage(content=body.prompt, role="user")
+    messages = [OpenAIMessage(content=body.prompt, role="user")]
+    # If system prompt is passed, create a fake message with the system prompt.
+    if body.system_prompt:
+        messages.insert(0, OpenAIMessage(content=body.system_prompt, role="system"))
+
     chat_body = ChatBody(
-        messages=[message],
+        messages=messages,
         use_context=body.use_context,
         stream=body.stream,
         include_sources=body.include_sources,

private_gpt/ui/ui.py

@@ -116,6 +116,17 @@ class PrivateGptUi:
         all_messages = [*build_history(), new_message]
         match mode:
             case "Query Docs":
+                # Add a system message to force the behaviour of the LLM
+                # to answer only questions about the provided context.
+                all_messages.insert(
+                    0,
+                    ChatMessage(
+                        content="You can only answer questions about the provided context. If you know the answer "
+                        "but it is not based in the provided context, don't provide the answer, just state "
+                        "the answer is not in the context provided.",
+                        role=MessageRole.SYSTEM,
+                    ),
+                )
                 query_stream = self._chat_service.stream_chat(
                     messages=all_messages,
                     use_context=True,

settings.yaml

@@ -22,6 +22,7 @@ ui:
 
 llm:
   mode: local
+
 embedding:
   # Should be matching the value above in most cases
   mode: local