What are the scholarly opinions regarding the uninterrupted recitation (muwālah) of Al-Fatiḥah and Al-Tashahhud, and is the prayer valid for one who pauses briefly between their phrases for recollection, shortness of breath, or stammering?

"Consecution is obligatory between the verses of Al-Fatiha and the words of the Tashahhud, because its omission would disrupt the order. The silence that breaks consecution is a long one that indicates a cessation of recitation, while a short silence does not break it. If the recitation is interrupted by a long silence without an excuse, then one must restart Al-Fatiha. But if it was due to an excuse (such as forgetfulness, sleep, or mistakenly moving to another surah), it does not invalidate it; rather, one builds upon it."