Base chat handler refactor for custom slash commands (jupyterlab#398)

* Adds attributes, starts adding to subclasses

* Consistent syntax

* Help for all handlers

* Fix slash ID error

* Iterate through entry points

* Fix typo in call to select()

* Moves config to magics, modifies extensions to attempt to load classes

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* Moves config to proper location, improves error logging

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* WIP: Updates per feedback, adds custom handler

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* Removes redundant code, style fixes

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* Removes unnecessary custom message

* Instantiates class

* Validates slash ID

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* Consistent arguments to chat handlers

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* Refactors to avoid intentionally unused params

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* Updates docs, removes custom handler from source and config

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* Renames process_message to match base class

* Adds needed parameter that had been deleted

* Joins lines in contributor doc

* Removes natural language routing type, which is not yet used

* Update docs/source/developers/index.md

Co-authored-by: Piyush Jain <piyushjain@duck.com>

* Update docs/source/developers/index.md

Co-authored-by: Piyush Jain <piyushjain@duck.com>

* Update docs/source/developers/index.md

Co-authored-by: Piyush Jain <piyushjain@duck.com>

* Revises per @3coins, avoids Latinism

* Removes Configurable, since we do not yet have configurable traits

* Uses Literal for validation

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---------

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Co-authored-by: Piyush Jain <piyushjain@duck.com>

docs/source/developers/index.md

@@ -120,3 +120,45 @@ class MyProvider(BaseProvider, FakeListLLM):
 ```
 
 Please note that this will only work with Jupyter AI magics (the `%ai` and `%%ai` magic commands). Custom prompt templates are not used in the chat interface yet.
+
+## Custom slash commands in the chat UI
+
+You can add a custom slash command to the chat interface by
+creating a new class that inherits from `BaseChatHandler`. Set
+its `id`, `name`, `help` message for display in the user interface,
+and `routing_type`. Each custom slash command must have a unique
+slash command. Slash commands can only contain ASCII letters, numerals,
+and underscores. Each slash command must be unique; custom slash
+commands cannot replace built-in slash commands.
+
+Add your custom handler in Python code:
+
+```python
+from jupyter_ai.chat_handlers.base import BaseChatHandler, SlashCommandRoutingType
+from jupyter_ai.models import HumanChatMessage
+
+class CustomChatHandler(BaseChatHandler):
+    id = "custom"
+    name = "Custom"
+    help = "A chat handler that does something custom"
+    routing_type = SlashCommandRoutingType(slash_id="custom")
+
+    def __init__(self, *args, **kwargs):
+        super().__init__(*args, **kwargs)
+
+    async def process_message(self, message: HumanChatMessage):
+        # Put your custom logic here
+        self.reply("<your-response>", message)
+```
+
+Jupyter AI uses entry points to support custom slash commands.
+In the `pyproject.toml` file, add your custom handler to the
+`[project.entry-points."jupyter_ai.chat_handlers"]` section:
+
+```
+[project.entry-points."jupyter_ai.chat_handlers"]
+custom = "custom_package:CustomChatHandler"
+```
+
+Then, install your package so that Jupyter AI adds custom chat handlers
+to the existing chat handlers.

packages/jupyter-ai/jupyter_ai/chat_handlers/__init__.py

@@ -1,5 +1,5 @@
 from .ask import AskChatHandler
-from .base import BaseChatHandler
+from .base import BaseChatHandler, SlashCommandRoutingType
 from .clear import ClearChatHandler
 from .default import DefaultChatHandler
 from .generate import GenerateChatHandler

packages/jupyter-ai/jupyter_ai/chat_handlers/ask.py

@@ -7,7 +7,7 @@
 from langchain.memory import ConversationBufferWindowMemory
 from langchain.prompts import PromptTemplate
 
-from .base import BaseChatHandler
+from .base import BaseChatHandler, SlashCommandRoutingType
 
 PROMPT_TEMPLATE = """Given the following conversation and a follow up question, rephrase the follow up question to be a standalone question.
 
@@ -26,6 +26,11 @@ class AskChatHandler(BaseChatHandler):
     to the LLM to generate the final reply.
     """
 
+    id = "ask"
+    name = "Ask with Local Data"
+    help = "Asks a question with retrieval augmented generation (RAG)"
+    routing_type = SlashCommandRoutingType(slash_id="ask")
+
     def __init__(self, retriever, *args, **kwargs):
         super().__init__(*args, **kwargs)
 

packages/jupyter-ai/jupyter_ai/chat_handlers/base.py

@@ -1,35 +1,81 @@
 import argparse
+import os
 import time
 import traceback
-
-# necessary to prevent circular import
-from typing import TYPE_CHECKING, Any, Dict, Optional, Type
+from typing import (
+    TYPE_CHECKING,
+    Awaitable,
+    ClassVar,
+    Dict,
+    List,
+    Literal,
+    Optional,
+    Type,
+)
 from uuid import uuid4
 
+from dask.distributed import Client as DaskClient
 from jupyter_ai.config_manager import ConfigManager, Logger
-from jupyter_ai.models import AgentChatMessage, HumanChatMessage
+from jupyter_ai.models import AgentChatMessage, ChatMessage, HumanChatMessage
 from jupyter_ai_magics.providers import BaseProvider
 
+# necessary to prevent circular import
+from pydantic import BaseModel
+
 if TYPE_CHECKING:
     from jupyter_ai.handlers import RootChatHandler
 
 
+# Chat handler type, with specific attributes for each
+class HandlerRoutingType(BaseModel):
+    routing_method: ClassVar[str] = Literal["slash_command"]
+    """The routing method that sends commands to this handler."""
+
+
+class SlashCommandRoutingType(HandlerRoutingType):
+    routing_method = "slash_command"
+
+    slash_id: Optional[str]
+    """Slash ID for routing a chat command to this handler. Only one handler
+    may declare a particular slash ID. Must contain only alphanumerics and
+    underscores."""
+
+
 class BaseChatHandler:
     """Base ChatHandler class containing shared methods and attributes used by
     multiple chat handler classes."""
 
+    # Class attributes
+    id: ClassVar[str] = ...
+    """ID for this chat handler; should be unique"""
+
+    name: ClassVar[str] = ...
+    """User-facing name of this handler"""
+
+    help: ClassVar[str] = ...
+    """What this chat handler does, which third-party models it contacts,
+    the data it returns to the user, and so on, for display in the UI."""
+
+    routing_type: HandlerRoutingType = ...
+
     def __init__(
         self,
         log: Logger,
         config_manager: ConfigManager,
         root_chat_handlers: Dict[str, "RootChatHandler"],
         model_parameters: Dict[str, Dict],
+        chat_history: List[ChatMessage],
+        root_dir: str,
+        dask_client_future: Awaitable[DaskClient],
     ):
         self.log = log
         self.config_manager = config_manager
         self._root_chat_handlers = root_chat_handlers
         self.model_parameters = model_parameters
+        self._chat_history = chat_history
         self.parser = argparse.ArgumentParser()
+        self.root_dir = os.path.abspath(os.path.expanduser(root_dir))
+        self.dask_client_future = dask_client_future
         self.llm = None
         self.llm_params = None
         self.llm_chain = None

packages/jupyter-ai/jupyter_ai/chat_handlers/clear.py

@@ -2,13 +2,17 @@
 
 from jupyter_ai.models import ChatMessage, ClearMessage
 
-from .base import BaseChatHandler
+from .base import BaseChatHandler, SlashCommandRoutingType
 
 
 class ClearChatHandler(BaseChatHandler):
-    def __init__(self, chat_history: List[ChatMessage], *args, **kwargs):
+    id = "clear"
+    name = "Clear chat messages"
+    help = "Clears the displayed chat message history only; does not clear the context sent to chat providers"
+    routing_type = SlashCommandRoutingType(slash_id="clear")
+
+    def __init__(self, *args, **kwargs):
         super().__init__(*args, **kwargs)
-        self._chat_history = chat_history
 
     async def process_message(self, _):
         self._chat_history.clear()

packages/jupyter-ai/jupyter_ai/chat_handlers/default.py

@@ -12,7 +12,7 @@
     SystemMessagePromptTemplate,
 )
 
-from .base import BaseChatHandler
+from .base import BaseChatHandler, SlashCommandRoutingType
 
 SYSTEM_PROMPT = """
 You are Jupyternaut, a conversational assistant living in JupyterLab to help users.
@@ -32,10 +32,14 @@
 
 
 class DefaultChatHandler(BaseChatHandler):
-    def __init__(self, chat_history: List[ChatMessage], *args, **kwargs):
+    id = "default"
+    name = "Default"
+    help = "Responds to prompts that are not otherwise handled by a chat handler"
+    routing_type = SlashCommandRoutingType(slash_id=None)
+
+    def __init__(self, *args, **kwargs):
         super().__init__(*args, **kwargs)
         self.memory = ConversationBufferWindowMemory(return_messages=True, k=2)
-        self.chat_history = chat_history
 
     def create_llm_chain(
         self, provider: Type[BaseProvider], provider_params: Dict[str, str]
@@ -80,8 +84,8 @@ def clear_memory(self):
         self.reply(reply_message)
 
         # clear transcript for new chat clients
-        if self.chat_history:
-            self.chat_history.clear()
+        if self._chat_history:
+            self._chat_history.clear()
 
     async def process_message(self, message: HumanChatMessage):
         self.get_llm_chain()

packages/jupyter-ai/jupyter_ai/chat_handlers/generate.py

@@ -6,7 +6,7 @@
 from typing import Dict, List, Optional, Type
 
 import nbformat
-from jupyter_ai.chat_handlers import BaseChatHandler
+from jupyter_ai.chat_handlers import BaseChatHandler, SlashCommandRoutingType
 from jupyter_ai.models import HumanChatMessage
 from jupyter_ai_magics.providers import BaseProvider
 from langchain.chains import LLMChain
@@ -216,11 +216,13 @@ def create_notebook(outline):
 
 
 class GenerateChatHandler(BaseChatHandler):
-    """Generates a Jupyter notebook given a description."""
+    id = "generate"
+    name = "Generate Notebook"
+    help = "Generates a Jupyter notebook, including name, outline, and section contents"
+    routing_type = SlashCommandRoutingType(slash_id="generate")
 
-    def __init__(self, root_dir: str, *args, **kwargs):
+    def __init__(self, *args, **kwargs):
         super().__init__(*args, **kwargs)
-        self.root_dir = os.path.abspath(os.path.expanduser(root_dir))
         self.llm = None
 
     def create_llm_chain(

packages/jupyter-ai/jupyter_ai/chat_handlers/help.py

@@ -4,7 +4,7 @@
 
 from jupyter_ai.models import AgentChatMessage, HumanChatMessage
 
-from .base import BaseChatHandler
+from .base import BaseChatHandler, SlashCommandRoutingType
 
 HELP_MESSAGE = """Hi there! I'm Jupyternaut, your programming assistant.
 You can ask me a question using the text box below. You can also use these commands:
@@ -29,6 +29,11 @@ def HelpMessage():
 
 
 class HelpChatHandler(BaseChatHandler):
+    id = "help"
+    name = "Help"
+    help = "Displays a help message in the chat message area"
+    routing_type = SlashCommandRoutingType(slash_id="help")
+
     def __init__(self, *args, **kwargs):
         super().__init__(*args, **kwargs)
 

packages/jupyter-ai/jupyter_ai/chat_handlers/learn.py

@@ -24,19 +24,20 @@
 )
 from langchain.vectorstores import FAISS
 
-from .base import BaseChatHandler
+from .base import BaseChatHandler, SlashCommandRoutingType
 
 INDEX_SAVE_DIR = os.path.join(jupyter_data_dir(), "jupyter_ai", "indices")
 METADATA_SAVE_PATH = os.path.join(INDEX_SAVE_DIR, "metadata.json")
 
 
 class LearnChatHandler(BaseChatHandler):
-    def __init__(
-        self, root_dir: str, dask_client_future: Awaitable[DaskClient], *args, **kwargs
-    ):
+    id = "learn"
+    name = "Learn Local Data"
+    help = "Pass a list of files and directories. Once converted to vector format, you can ask about them with /ask."
+    routing_type = SlashCommandRoutingType(slash_id="learn")
+
+    def __init__(self, *args, **kwargs):
         super().__init__(*args, **kwargs)
-        self.root_dir = root_dir
-        self.dask_client_future = dask_client_future
         self.parser.prog = "/learn"
         self.parser.add_argument("-a", "--all-files", action="store_true")
         self.parser.add_argument("-v", "--verbose", action="store_true")