Seasonal hiring: what is paying well this year? (update)

A staffing agency says some roles convert to permanent after 4 weeks. It has been weighing on me all week. I would like to avoid a gap in my résumé. Has anyone been converted to permanent?

Keep a list of supervisors' names. A reference from one of them helped me land my next job.

Thanks for writing this out. I went through something close to it last year, and it settled down once I kept a simple log of every call and form.