Is it permissible to work under a contract with a fixed salary (3,0 SAR) in addition to a 1% commission on sales, with a guarantee that the total income will not be less than 6,0 SAR, and if it is not permissible, what is the proposed Sharia-compliant solution?

For the validity of ijarah (leasing/hiring), the ujrah (rent/wage) must be known. If it is a specified amount, it is permissible by the consensus of scholars. Regarding combining a fixed wage with a percentage, there is a difference of opinion among jurists. Most scholars, including the Hanbalis, prohibited it. However, one narration from Ahmad and the opinion of some early Muslims (Salaf) permit it. According to the view that permits it, if the shop owner commits to supplementing the salary to six thousand in case the total falls short of that, and takes the excess above six thousand when there is an increase, there appears to be no impediment. The most appropriate approach is to agree upon a known salary that increases periodically, in order to avoid scholarly dispute.