OPM has circulated a template contract for deferred resignation with the following provision:
"[AGENCY] agrees to waive any debt owed by Employee to [AGENCY] pursuant to a recruitment incentive, student loan repayment, or other service agreement. [AGENCY] also agrees to waive any remaining service requirements from taking paid parental leave."
Unclear whether it applies to SMART, since SMART technically isn't your agency? Maybe the SMART program will send out clarification tomorrow.
Here's another provision to chew on:
"Employee forever waives, and will not pursue through any judicial, administrative, or other process, any action against [AGENCY] that is based on, arising from, or related to Employee’s employment at [AGENCY] or the deferred resignation offer, including any and all claims that were or could have been brought concerning said matters."
The OPM has made no promise you will be offered this contract if you send them a resignation email, but they do strongly imply this is the offer you are getting.