feat(prompt): prompt.stream(), options.endpoint (copilot-extensions#57)

BREAKING CHANGE: `prompt()` is now throwing an error if the API responds
with an error status code

Author: gr2m

README.md

@@ -422,6 +422,22 @@ await prompt({
 });
 ```
 
+#### `prompt.stream(message, options)`
+
+Works the same way as `prompt()`, but resolves with a `stream` key instead of a `message` key.
+
+```js
+import { prompt } from "@copilot-extensions/preview-sdk";
+
+const { requestId, stream } = prompt.stream("What is the capital of France?", {
+  token: process.env.TOKEN,
+});
+
+for await (const chunk of stream) {
+  console.log(new TextDecoder().decode(chunk));
+}
+```
+
 ### `getFunctionCalls()`
 
 Convenience metthod if a result from a `prompt()` call includes function calls.

index.d.ts

@@ -175,7 +175,7 @@ export interface OpenAICompatibilityPayload {
 export interface CopilotMessage {
   role: string;
   content: string;
-  copilot_references: MessageCopilotReference[];
+  copilot_references?: MessageCopilotReference[];
   copilot_confirmations?: MessageCopilotConfirmation[];
   tool_calls?: {
     function: {
@@ -300,8 +300,9 @@ export interface PromptFunction {
 }
 
 export type PromptOptions = {
-  model?: ModelName;
   token: string;
+  endpoint?: string;
+  model?: ModelName;
   tools?: PromptFunction[];
   messages?: InteropMessage[];
   request?: {
@@ -314,12 +315,25 @@ export type PromptResult = {
   message: CopilotMessage;
 };
 
+export type PromptStreamResult = {
+  requestId: string;
+  stream: ReadableStream<Uint8Array>;
+};
+
 // https://stackoverflow.com/a/69328045
 type WithRequired<T, K extends keyof T> = T & { [P in K]-?: T[P] };
 
 interface PromptInterface {
   (userPrompt: string, options: PromptOptions): Promise<PromptResult>;
   (options: WithRequired<PromptOptions, "messages">): Promise<PromptResult>;
+  stream: PromptStreamInterface;
+}
+
+interface PromptStreamInterface {
+  (userPrompt: string, options: PromptOptions): Promise<PromptStreamResult>;
+  (
+    options: WithRequired<PromptOptions, "messages">,
+  ): Promise<PromptStreamResult>;
 }
 
 interface GetFunctionCallsInterface {

index.test-d.ts

@@ -302,7 +302,6 @@ export function getUserConfirmationTest(payload: CopilotRequestPayload) {
 
 export async function promptTest() {
   const result = await prompt("What is the capital of France?", {
-    model: "gpt-4",
     token: "secret",
   });
 
@@ -311,7 +310,6 @@ export async function promptTest() {
 
   // with custom fetch
   await prompt("What is the capital of France?", {
-    model: "gpt-4",
     token: "secret",
     request: {
       fetch: () => {},
@@ -327,7 +325,6 @@ export async function promptTest() {
 
 export async function promptWithToolsTest() {
   await prompt("What is the capital of France?", {
-    model: "gpt-4",
     token: "secret",
     tools: [
       {
@@ -366,6 +363,24 @@ export async function promptWithoutMessageButMessages() {
   });
 }
 
+export async function otherPromptOptionsTest() {
+  const result = await prompt("What is the capital of France?", {
+    token: "secret",
+    model: "gpt-4",
+    endpoint: "https://api.githubcopilot.com",
+  });
+}
+
+export async function promptStreamTest() {
+  const result = await prompt.stream("What is the capital of France?", {
+    model: "gpt-4",
+    token: "secret",
+  });
+
+  expectType<string>(result.requestId);
+  expectType<ReadableStream<Uint8Array>>(result.stream);
+}
+
 export async function getFunctionCallsTest(
   promptResponsePayload: PromptResult,
 ) {

lib/prompt.js

@@ -1,15 +1,20 @@
 // @ts-check
 
 /** @type {import('..').PromptInterface} */
-export async function prompt(userPrompt, promptOptions) {
-  const options = typeof userPrompt === "string" ? promptOptions : userPrompt;
 
-  const promptFetch = options.request?.fetch || fetch;
-  const modelName = options.model || "gpt-4";
+function parsePromptArguments(userPrompt, promptOptions) {
+  const { request: requestOptions, ...options } =
+    typeof userPrompt === "string" ? promptOptions : userPrompt;
+
+  const promptFetch = requestOptions?.fetch || fetch;
+  const model = options.model || "gpt-4";
+  const endpoint =
+    options.endpoint || "https://api.githubcopilot.com/chat/completions";
 
   const systemMessage = options.tools
     ? "You are a helpful assistant. Use the supplied tools to assist the user."
     : "You are a helpful assistant.";
+  const toolsChoice = options.tools ? "auto" : undefined;
 
   const messages = [
     {
@@ -29,44 +34,87 @@ export async function prompt(userPrompt, promptOptions) {
     });
   }
 
-  const response = await promptFetch(
-    "https://api.githubcopilot.com/chat/completions",
-    {
-      method: "POST",
-      headers: {
-        accept: "application/json",
-        "content-type": "application/json; charset=UTF-8",
-        "user-agent": "copilot-extensions/preview-sdk.js",
-        authorization: `Bearer ${options.token}`,
-      },
-      body: JSON.stringify({
-        messages: messages,
-        model: modelName,
-        toolChoice: options.tools ? "auto" : undefined,
-        tools: options.tools,
-      }),
-    }
-  );
+  return [promptFetch, { ...options, messages, model, endpoint, toolsChoice }];
+}
 
-  if (response.ok) {
-    const data = await response.json();
+async function sendPromptRequest(promptFetch, options) {
+  const { endpoint, token, ...payload } = options;
+  const method = "POST";
+  const headers = {
+    accept: "application/json",
+    "content-type": "application/json; charset=UTF-8",
+    "user-agent": "copilot-extensions/preview-sdk.js",
+    authorization: `Bearer ${token}`,
+  };
 
-    return {
-      requestId: response.headers.get("x-request-id"),
-      message: data.choices[0].message,
-    };
+  const response = await promptFetch(endpoint, {
+    method,
+    headers,
+    body: JSON.stringify(payload),
+  });
+
+  if (response.ok) {
+    return response;
   }
 
+  const body = await response.text();
+  console.log({ body });
+
+  throw Object.assign(
+    new Error(
+      `[@copilot-extensions/preview-sdk] An error occured with the chat completions API`,
+    ),
+    {
+      name: "PromptError",
+      request: {
+        method: "POST",
+        url: endpoint,
+        headers: {
+          ...headers,
+          authorization: `Bearer [REDACTED]`,
+        },
+        body: payload,
+      },
+      response: {
+        status: response.status,
+        headers: [...response.headers],
+        body: body,
+      },
+    },
+  );
+}
+export async function prompt(userPrompt, promptOptions) {
+  const [promptFetch, options] = parsePromptArguments(
+    userPrompt,
+    promptOptions,
+  );
+  const response = await sendPromptRequest(promptFetch, options);
   const requestId = response.headers.get("x-request-id");
+
+  const data = await response.json();
+
   return {
-    requestId: requestId,
-    message: {
-      role: "Sssistant",
-      content: `Sorry, an error occured with the chat completions API. (Status: ${response.status}, request ID: ${requestId})`,
-    },
+    requestId,
+    message: data.choices[0].message,
   };
 }
 
+prompt.stream = async function promptStream(userPrompt, promptOptions) {
+  const [promptFetch, options] = parsePromptArguments(
+    userPrompt,
+    promptOptions,
+  );
+  const response = await sendPromptRequest(promptFetch, {
+    ...options,
+    stream: true,
+  });
+
+  return {
+    requestId: response.headers.get("x-request-id"),
+    stream: response.body,
+  };
+};
+
 /** @type {import('..').GetFunctionCallsInterface} */
 export function getFunctionCalls(payload) {
   const functionCalls = payload.message.tool_calls;