Idaho - Accepted An Emailed $80k Salaried Offer, Now Employer Wants To Permanently Change Me To $35/hour

Location: Idaho

I’m looking for legal guidance on whether I should be concerned about this situation or if this is simply a lawful change in compensation.

About 8 months ago, I accepted a full-time position after receiving an offer letter by email stating my compensation would be $80,000 annually. I accepted the offer by replying via email and left my previous job based on that offer. My position was newly created, so there isn’t anyone else in the same role.

Recently, during discussions related to an upcoming surgery and how I’d work during recovery, my employer told me they realized my position was “mistakenly” classified as salaried. They said only certain management positions are salaried at the company and that my role should have been hourly.
They are now proposing to permanently change me to $35/hour. They said their finance department calculated that rate because hourly employees receive PTO. However, I’ve actually been accruing and using PTO while I’ve been a salaried employee, and neither my offer letter nor the employee handbook states that salaried employees don’t receive PTO or that my compensation could be adjusted if my classification changed.
Everything was discussed verbally. I asked for time to think about it and followed up with an email summarizing my understanding of the proposal. My manager replied that we’d discuss it further in person.

My questions are:
Can an employer in Idaho prospectively change an employee from salaried to hourly and reduce the equivalent annual compensation after the employee accepted a written $80,000 offer?
Does the fact that the offer was made in writing and accepted by email have any legal significance?
Is there anything I should or shouldn’t do before my follow-up meeting?
At this point, is documenting everything in writing the right approach?

I’m not looking to sue anyone
or escalate things unnecessarily. I’m just trying to understand my rights and make sure I handle tomorrow’s meeting appropriately.