Record and play back OpenAI responses in dev server

Now we can iterated faster, and save costs.

.gitignore

@@ -6,3 +6,4 @@ tsconfig.tsbuildinfo
 .turbo
 cdk.out
 cdk.context.json
+dev-server/openai-tapes

README.md

@@ -49,12 +49,19 @@ For more information on the Google Custom Search JSON API, visit:
 
 ### Dev Server
 
-To start the development server (which watches for file changes), run:
+To start the dev server (which watches for file changes), run:
 
 ```
 npm run dev
 ```
 
+Recording and replaying OpenAI responses can be enabled by starting the dev
+server as follows:
+
+```
+OPENAI_BASE_URL=http://localhost:3001/v1/ npm run dev
+```
+
 ### Browser
 
 Open [http://localhost:3000](http://localhost:3000) in your browser.

dev-server/run.ts

@@ -1,7 +1,9 @@
+import path from 'path';
 import {serve} from '@hono/node-server';
 import {serveStatic} from '@hono/node-server/serve-static';
 import {Hono} from 'hono';
 import {compress} from 'hono/compress';
+import talkbackModule from 'talkback';
 import {authMiddleware} from './auth-middleware.js';
 import './stub-awslambda.js';
 
@@ -23,3 +25,20 @@ serve({fetch: app.fetch, port: 3000}, ({address, port}) => {
 
   return console.log(`Started dev server at ${serverUrl}`);
 });
+
+if (process.env.OPENAI_BASE_URL?.startsWith(`http://localhost`)) {
+  const {port} = new URL(process.env.OPENAI_BASE_URL);
+
+  // hacky kind of es module interop
+  const talkback = talkbackModule as unknown as typeof talkbackModule.default;
+
+  const talkbackServer = talkback({
+    host: `https://api.openai.com`,
+    record: talkback.Options.RecordMode.NEW,
+    port: parseInt(port, 10),
+    path: path.join(import.meta.dirname, `openai-tapes`),
+    summary: false,
+  });
+
+  await talkbackServer.start(() => console.log(`Talkback server started`));
+}

package.json

@@ -73,6 +73,7 @@
     "source-map-loader": "^4.0.1",
     "swc-loader": "^0.2.6",
     "tailwindcss": "^3.2.7",
+    "talkback": "^3.0.2",
     "tsx": "^4.7.1",
     "turbo": "~1.11.3",
     "typescript": "^5.4.2",