This uses Gemini's native [thinking summaries](https://cloud.google.com/vertex-ai/generative-ai/docs/thinking#thought-summaries) which were recently added to the API. Why? The grafted thinking would sometimes cause weird issues where the model, especially Gemini 2.5 Flash, got confused and put dyad tags like `<dyad-write>` inside the `<think>` tags. This also improves the UX because you can see the native thoughts rather than having the Gemini response load for a while without any feedback. I tried adding Anthropic extended thinking, however it requires temp to be set at 1, which isn't ideal for Dyad's use case where we need precise syntax following.
Fake LLM Server
A simple server that mimics the OpenAI streaming chat completions API for testing purposes.
Features
- Implements a basic version of the OpenAI chat completions API
- Supports both streaming and non-streaming responses
- Always responds with "hello world" message
- Simulates a 429 rate limit error when the last message is "[429]"
- Configurable through environment variables
Installation
npm install
Usage
Start the server:
# Development mode
npm run dev
# Production mode
npm run build
npm start
Example usage
curl -X POST http://localhost:3500/v1/chat/completions \
-H "Content-Type: application/json" \
-d '{"messages":[{"role":"user","content":"Say something"}],"model":"any-model","stream":true}'
The server will be available at http://localhost:3500 by default.
API Endpoints
POST /v1/chat/completions
This endpoint mimics OpenAI's chat completions API.
Request Format
{
"messages": [{ "role": "user", "content": "Your prompt here" }],
"model": "any-model",
"stream": true
}
- Set
stream: trueto receive a streaming response - Set
stream: falseor omit it for a regular JSON response
Response
For non-streaming requests, you'll get a standard JSON response:
{
"id": "chatcmpl-123456789",
"object": "chat.completion",
"created": 1699000000,
"model": "fake-model",
"choices": [
{
"index": 0,
"message": {
"role": "assistant",
"content": "hello world"
},
"finish_reason": "stop"
}
]
}
For streaming requests, you'll receive a series of server-sent events (SSE), each containing a chunk of the response.
Simulating Rate Limit Errors
To test how your application handles rate limiting, send a message with content exactly equal to [429]:
{
"messages": [{ "role": "user", "content": "[429]" }],
"model": "any-model"
}
This will return a 429 status code with the following response:
{
"error": {
"message": "Too many requests. Please try again later.",
"type": "rate_limit_error",
"param": null,
"code": "rate_limit_exceeded"
}
}
Configuration
You can configure the server by modifying the PORT variable in the code.
Use Case
This server is primarily intended for testing applications that integrate with OpenAI's API, allowing you to develop and test without making actual API calls to OpenAI.