As a weekend vibe coding project, I implemented this tool to fix the problem for myself. It’s a lightweight Chrome extension that lets you define and automatically inject a custom prompt to control the AI's personality.
This extension prepends the instructions to the user's message before each fetch request is sent. It's a "simulated" system prompt, but it works surprisingly well and I think this is more effective than relying on custom instructions.
This can also be adjusted mid-conversation without needing to launch a new conversation. It's 100% local. Nothing is ever sent to any server but OpenAI's. It collects zero data.
It's a simple tool for a simple problem. I'm sharing it here because I figure others might find it useful too. I'd love to hear any thoughts or feedback you have.
The GitHub repo is here: https://github.com/althea-tfyqa/deglaze-me