When did the Bracha on nerot Shabbat come into play? I know that the Mishna mentions generally the mitzva mid'rabanan to light a light on Shabbos. But when did klal yisrael begin saying the Bracha?
Hagahos Maimonios to Shabbos 5:1 quotes the Yerushalmi in two places as giving the text of the berachah, although neither of those appears in our editions of the Yerushalmi.
Tosafos to Shabbos 25b quotes Rabbeinu Meshulam as saying that no berachah should be said, but Rabbeinu Tam disagrees and says that it should be said. It also quotes Seder R. Amram Gaon, who brings the text of the berachah.