Hand an agent a key without pasting it in the chat
When an agent needs an API key or token, it asks in a private box. The key never enters the chat, and it is deleted after 24 hours.
Some work needs a key: an API token, an auth key for a server. The agent now asks for it in a masked box in the conversation. Save securely hands it over; Decline says no, and the agent carries on without it.
The key is kept in one locked file on this Mac, readable only by you. Wherever it would show up in the agent's output it reads as the secret's name instead, and it is deleted after 24 hours or when the chat is deleted.