# Open Web UI Stream Chunk Filter for Zed IDE

This adapter script resolves the following error in Zed IDE:

```
data did not match any variant of untagged enum ResponseStreamResult
```

which occurs when using a custom Open Web UI model (pipe functions). Open Web UI sends invalid chunks in the stream, causing parsing exceptions.

---

## What the adapter does

- Proxies requests to Open Web UI  
- Filters out and removes invalid chunks from the stream, allowing Zed IDE to properly receive responses  
- Supports streaming
- Allows overriding system messages in requests (optional)  
- **Simulates OpenAI-style function calling (`tool_calls`) using special stream markers** controlled by the environment variable `EMULATE_TOOLS_CALLING` (default: enabled)

---

## Tool Calling Emulation

If your model outputs function definitions inside the following block:

```
<tools_calling>
{ ... json ... }
</tools_calling>
```

The adapter will:

- Detect the block  
- Extract and parse the JSON  
- Convert it into OpenAI-compatible `tool_calls` chunks  
- Send those chunks to the client as if native function calling were supported  

### Expected JSON Structure

The JSON inside `<tools_calling>...</tools_calling>` must have the following structure:

```json
{
  "model": "<string>",
  "functions": [
    {
      "index": <integer>,
      "function_call": {
        "name": "<string>",
        "arguments": "<JSON string>"
      },
    }
  ]
}
```

Notes:
- The `arguments` field must be a valid **stringified JSON object**  
- The outer structure must contain a `functions` list  
- Each entry represents one tool call  

---

## Usage

1. Clone or download the script  
2. Set environment variables:  
   - `OPENWEBUI_URL` — URL of your Open Web UI server  
   - `OPENWEBUI_API_KEY` — API key for access  
   - (optional) `ZED_SYSTEM_PROMPT_FILE` — path to a file with a system prompt  
   - (optional) `ZED_SYSTEM_PROMPT_MODE` — mode for handling system messages, one of:  
     - `default` (leave system messages unchanged)  
     - `replace` (replace all system messages with the one from the file)  
     - `disable` (remove all system messages)  
   - (optional) `EMULATE_TOOLS_CALLING` — `true` or `false` to enable/disable tool calling emulation (default: `true`)  
3. Install dependencies:

```bash
pip install fastapi httpx uvicorn python-dotenv
```

4. Run the server:

```bash
python OpenWEBUI_tool_calling_proxy.py
```

5. Configure Zed IDE to use this proxy instead of a direct connection to Open Web UI  

---

## Important notes

- The invalid chunk issue only occurs with Open Web UI custom models (pipe functions)  
- Models served via OpenRouter are not affected  
- The tool calling emulation requires output in the `<tools_calling>...</tools_calling>` format  
- This is a temporary and pragmatic workaround to enable compatibility with OpenAI-like clients  

---

If you have any questions, feel free to reach out.

---

Author: Savkin Vladimir  
Date: 2025