What is the definition of a "shawt" (lap/round) in Sa'i (the ritual circumambulation between Safa and Marwah), and is the Sa'i seven ashwat in total (going and returning), or is going seven and returning another seven?

The correct view, supported by the texts, is that the journey from Safa to Marwah counts as one circuit (shawṭ), and from Marwah to Safa counts as another circuit. This is the opinion adopted by the majority of scholars. What further confirms the invalidity of the other view is that the Prophet, peace and blessings be upon him, concluded his Sa'i at Marwah. Had the going and returning been counted as a single circuit, his conclusion would have been at Safa.