Add client and types for API v2

[cjcenizal]

Summary

The API v2 client is unopinionated. It accepts configuration options that are a 1:1 representation of the API configuration options. It also doesn't preprocess the results -- that's left to the consumer. This will make it easier for folks who are familiar with the API or reading the API docs to map concepts to the client.

To-do

• Enable using a JWT instead of an API key.

Bug fixes

• Events might be very large, e.g. many or large search results, which causes them to be split across multiple chunks. Original code didn't accommodate for this, and risked a JSON.parse error. The code now buffers these chunks until it detects the completion of the event (indicated by a successful JSON.parse call), at which point it processes the buffered event.

New features

• Errors are emitted as regular events to the onStreamEvent handler.
• Calling streamQueryV2 returns { cancelStream } which can be used to cancel the stream.

Breaking changes

Package interface is now:

import {
  streamQueryV1,
  ApiV1,
  streamQueryV2,
  ApiV2,
} from "@vectara/stream-query-client";

The API has been dramatically simplified and ergonomics much improved, so I don't think we need to inject any opinions or sugar into the interface. As a result, requests are now configured with the same objects and fields as described in the Corpus Query docs.

StreamEvent now has this shape:

export type StreamEvent =
  | ErrorEvent
  | SearchResultsEvent
  | ChatInfoEvent
  | GenerationChunkEvent
  | FactualConsistencyScoreEvent
  | EndEvent;

export type ErrorEvent = {
  type: "error";
  messages?: string[];
};

export type SearchResultsEvent = {
  type: "searchResults";
  searchResults: SearchResult[];
};

export type ChatInfoEvent = {
  type: "chatInfo";
  chatId: string;
  turnId: string;
};

export type GenerationChunkEvent = {
  type: "generationChunk";
  updatedText: string;
  generationChunk: string;
};

export type FactualConsistencyScoreEvent = {
  type: "factualConsistencyScore";
  factualConsistencyScore: number;
};

export type EndEvent = {
  type: "end";
};

References

https://javascript.info/fetch-abort
whatwg/streams#1255
https://github.com/openai/openai-node/blob/master/src/streaming.ts

[cjcenizal]

I need to switch this back before merging.

[cjcenizal]

I need to switch this back before merging.

[mrderyk]

Quick request to update the types.