Function write_preference 

pub fn write_preference(
    text: &str,
    reason: &str,
    deny_mention: &People,
    deny_reply_to: &People,
) -> Result<UserRule>

Write one prose rule, from any caller. It is not also posted to the seat pack. The row’s basis is the label: the person’s when they typed it or it is in the prompt the hook kept, else the agent’s, which ljos rules lists as unverified.

Errors

The text or the reason is empty, a handle is not a login, or the file cannot be written.