---
title: "Factory Droid Wants OpenAI Mode: Fixing VibeProxy and CLIProxyAPI"
author: "Luis Colunga"
date: 2026-04-01
description: "How to make Factory Droid's OpenAI provider work through VibeProxy or CLIProxyAPIPlus without unsupported parameter errors."
tags: ["ai-tools","dev"]
url: https://www.luiscolunga.com/posts/factory-openai-provider-cliproxyapiplus/
---

# Factory Droid Wants OpenAI Mode: Fixing VibeProxy and CLIProxyAPI


Factory (Droid) recently started pushing the `openai` provider for GPT models instead of the old `generic-chat-completion-api`. Even though most guides still say to use generic for everything, I tried switching. It broke instantly.

Factory has three provider types. `openai` hits the Responses API (`/v1/responses`), which is what you need for GPT-5+ and Codex. `anthropic` is for Claude. `generic-chat-completion-api` is the standard Chat Completions API (`/v1/chat/completions`) for things like OpenRouter or Fireworks. The difference is the API format, not the models themselves.

When I flipped to `provider: "openai"`, I started seeing `400` errors in my proxy logs: `{"detail":"Unsupported parameter: prompt_cache_retention"}`. 

The issue is that CLIProxyAPIPlus uses your ChatGPT subscription tokens, so it routes requests through `chatgpt.com/backend-api/codex/responses` instead of the official `api.openai.com` endpoint. `prompt_cache_retention` is an OpenAI parameter that controls how long prompt prefixes stay in memory. The subscription backend doesn't support it, but Factory sends it anyway because it assumes you're hitting the official API.

## The Fix

You need to do two things.

First, strip that parameter in your proxy config. I'm using VibeProxy, but this works for any CLIProxyAPIPlus setup. Edit your `config.yaml` (on VibeProxy, use the one in `/Applications/VibeProxy.app/Contents/Resources/config.yaml` so your changes actually persist):

```yaml
payload:
  filter:
    - models:
        - name: "gpt-*"
      params:
        - "prompt_cache_retention"
```

Then update your `~/.factory/settings.json`. Change `provider` to `"openai"` and move your reasoning settings to the new nested format:

```json
{
  "model": "gpt-5.4",
  "baseUrl": "http://localhost:8317/v1",
  "apiKey": "dummy-not-used",
  "displayName": "GPT 5.4 (Low)",
  "extraArgs": {
    "reasoning": {"effort": "low"}
  },
  "provider": "openai"
}
```

The `baseUrl` stays the same. The proxy handles both endpoints on the same port.

I checked it with curl first to make sure the proxy was happy with the Responses API format:

```bash
curl -s -X POST http://localhost:8317/v1/responses \
  -H "Content-Type: application/json" \
  -H "Authorization: Bearer dummy-not-used" \
  -d '{
    "model": "gpt-5.4",
    "input": "Say hello in one word",
    "reasoning": {"effort": "low"},
    "stream": true
  }'
```

Everything worked fine once `prompt_cache_retention` was out of the way.