Green’s Dictionary of Slang

yes indeed! I agree!

1811		Lex. Balatronicum n.p.: All right! A favourite expression among thieves, to signify that all is as they wish, or proper for their purpose. All right, hand down the jemmy; every thing is in proper order, give me the crow.
1976		Jenkins & Shrake Limo 149: To Jeff she said, ‘You ought to see my dad’s apartment. He can show movies and everything.’ ‘All right!’ Jeff said.
1978		Eble Campus Sl. Apr. 1: aw-right! – exclamation, terrific, great.
1982		W.D. Myers Won’t Know Till I Get There 90: Eddie had a tryout with the Yankees! [...] If he makes the club he’ll go to one of their farm teams. Allright!!!
2005		E. Weiner Big Boat to Bye-Bye 120: [A]ll riiiight!