# gr2gw: Universal Gradio to OpenAI LLM gateway

A zero-dependency, high-performance Go proxy server that introspects any Gradio chat space (such as Hugging Face Spaces or custom deployments) and exposes a standards-compliant OpenAI `/v1/chat/completions` and `/v1/models` HTTP API.

Default demo space: `https://ghost2513-openai-gpt-oss-120b.hf.space`

## Features

- **Zero external dependencies**: Pure Go standard library (`net/http`, `encoding/json`, `bufio`, etc.).
- **Automatic space introspection**: Dynamically queries `/gradio_api/info`, `/config`, and Hugging Face space metadata to discover models, endpoints, and input parameter mappings.
- **Native Tencent Hunyuan 3 (`tencent-hy3`) support**:
  - Full native zero-degradation handling for official spaces like `https://tencent-hy3.hf.space`.
  - Maps `functions_json_str` natively without polluting the system prompt.
  - Preserves multi-turn reasoning content and tool call history in standard OpenAI message schemas.
  - Maps `reasoning_effort` (`no_think`, `low`, `high`) directly to `think_level`.
- **Universal multi-turn handling**:
  - Automatically formats conversation history into structured inputs when the space supports them.
  - Transparently composes multi-turn dialogue (`System`, `User`, `Assistant`) into single prompt inputs when the space only accepts a single message textbox.
  - Automatically pads hidden/State inputs (e.g. Gradio State components) to prevent backend argument count mismatches.
- **Real-time streaming & accumulation filter**:
  - Automatically computes token deltas from cumulative or incremental Gradio SSE output streams (including 2D Hy3 frames `[[content, reasoning, tool_calls, history]]`).
  - Emits standards-compliant `chat.completion.chunk` SSE events in real time.
- **Thinking & reasoning token separation**:
  - Streams native reasoning chunks as `delta.reasoning_content` in real time.
  - Detects `<think>...</think>` tags in real time as fallback for standard spaces.
  - Separates reasoning into `delta.reasoning_content` (streaming) and `message.reasoning_content` (non-streaming).
  - Keeps `content` clean without tag leakage.
- **Full tool calling & function interception**:
  - Formats schemas into native `functions_json_str` (Hy3) or system prompts (standard spaces).
  - **`StreamToolCallFilter`**: Stateful sliding-window filter that prevents `<tool_call>` tags from leaking into `delta.content`. Emits structured OpenAI `delta.tool_calls` chunks and sets `finish_reason: "tool_calls"`.
  - Seamlessly maintains multi-turn context when tool results are submitted back via `role: "tool"`.
- **Built-in SOCKS5 proxy client**:
  - Full RFC 1928 / RFC 1929 implementation with domain resolution (`socks5h://`), IPv4, IPv6, and username/password auth.
- **Dynamic space override**:
  - Switch the target Gradio space on-the-fly per request using the `X-Gradio-Space` or `X-Space-URL` HTTP headers.
- **Fibonacci retry engine**:
  - Resilient backoff retry mechanism (1s, 1s, 2s, 3s, 5s) for transient network hiccups.

## Installation

```bash
go install code.luxferre.top/luxferre/gr2gw@latest
```

## Build

```bash
make build
```

Binary will be compiled to `bin/gr2gw`.

To run tests:
```bash
make test
```

## Usage

### Quick start

Run with the default space (`https://ghost2513-openai-gpt-oss-120b.hf.space`):
```bash
./bin/gr2gw -port 8080
```

Target any other Gradio space:
```bash
./bin/gr2gw -space https://ericsqin-hy3.hf.space -port 8080
```

With SOCKS5 proxy:
```bash
./bin/gr2gw -space https://ghost2513-openai-gpt-oss-120b.hf.space -socks socks5://127.0.0.1:1080
```

### CLI flags

| Flag | Default | Description |
|------|---------|-------------|
| `-space`, `-url` | `https://ghost2513-openai-gpt-oss-120b.hf.space` | Target Gradio space URL |
| `-port` | `8080` | Port to listen on |
| `-host` | `0.0.0.0` | Host interface to bind to |
| `-socks`, `-proxy`, `-socks5` | `""` | SOCKS5 proxy URL (`socks5://user:pass@host:port`) |
| `-user-agent`, `-ua` | Firefox string | Custom User-Agent header |
| `-timeout` | `300` | Upstream request timeout in seconds |

### Environment variables

- `GRADIO_SPACE_URL`: default Gradio space URL fallback.
- `ALL_PROXY`, `SOCKS5_PROXY`, `SOCKS_PROXY`: default SOCKS5 proxy URL fallback.

## API examples

### List models

```bash
curl http://localhost:8080/v1/models
```

Response:
```json
{
  "object": "list",
  "data": [
    {
      "id": "openai/gpt-oss-120b",
      "object": "model",
      "created": 1788756307,
      "owned_by": "gradio"
    },
    {
      "id": "gpt-oss-120b",
      "object": "model",
      "created": 1788756307,
      "owned_by": "gradio"
    }
  ]
}
```

### Chat completions (non-streaming)

```bash
curl http://localhost:8080/v1/chat/completions \
  -H "Content-Type: application/json" \
  -d '{
    "model": "openai/gpt-oss-120b",
    "messages": [
      {"role": "user", "content": "What is the capital of France?"}
    ]
  }'
```

Response:
```json
{
  "id": "chatcmpl-16425f9d-c350-47a1-9a6d-e9ce10871545",
  "object": "chat.completion",
  "created": 1788756310,
  "model": "openai/gpt-oss-120b",
  "choices": [
    {
      "index": 0,
      "message": {
        "role": "assistant",
        "content": "Paris is the capital of France."
      },
      "finish_reason": "stop"
    }
  ],
  "usage": {
    "prompt_tokens": 0,
    "completion_tokens": 0,
    "total_tokens": 0
  }
}
```

### Chat completions (streaming)

```bash
curl -N http://localhost:8080/v1/chat/completions \
  -H "Content-Type: application/json" \
  -d '{
    "model": "openai/gpt-oss-120b",
    "messages": [
      {"role": "user", "content": "Count from 1 to 5."}
    ],
    "stream": true
  }'
```

### Tool calling

```bash
curl http://localhost:8080/v1/chat/completions \
  -H "Content-Type: application/json" \
  -d '{
    "model": "openai/gpt-oss-120b",
    "messages": [
      {"role": "user", "content": "What is the weather in Tokyo?"}
    ],
    "tools": [{
      "type": "function",
      "function": {
        "name": "get_weather",
        "description": "Get current weather in a location",
        "parameters": {
          "type": "object",
          "properties": {
            "location": {"type": "string", "description": "City name"}
          },
          "required": ["location"]
        }
      }
    }]
  }'
```

Response:
```json
{
  "id": "chatcmpl-32727c62-ef2a-4866-855b-f1c7ec2b8023",
  "object": "chat.completion",
  "created": 1788756322,
  "model": "openai/gpt-oss-120b",
  "choices": [
    {
      "index": 0,
      "message": {
        "role": "assistant",
        "content": null,
        "tool_calls": [
          {
            "id": "call_3d4c016a",
            "type": "function",
            "function": {
              "name": "get_weather",
              "arguments": "{\"location\":\"Tokyo\"}"
            }
          }
        ]
      },
      "finish_reason": "tool_calls"
    }
  ],
  "usage": {
    "prompt_tokens": 0,
    "completion_tokens": 0,
    "total_tokens": 0
  }
}
```

### Dynamic target space override

Override the target space per request without restarting the server:

```bash
curl http://localhost:8080/v1/chat/completions \
  -H "Content-Type: application/json" \
  -H "X-Gradio-Space: https://ericsqin-hy3.hf.space" \
  -d '{
    "messages": [
      {"role": "user", "content": "Hello!"}
    ]
  }'
```

## Credits

Created by Luxferre in 2026, released into the public domain with no warranties.