Her hair spills in flames and her guitar work — a fusion of flamenco and the Mississippi delta — follows suit, but Patty Larkin's voice has the cool, clear sweetness of ice dissolving in mint tea. Of all the Boston caféistas, Larkin is the only guitarist who deserves an instructional DVD, even as she comes on with more instinct than technique. On the new Watching the Sky, Larkin goes all Rundgren on her folkie following, tracking and playing every instrument — violin-bowed baritone guitar, electronic loops, toy organs and door chimes — and turning her 21st-century alienation into vignettes that sound more like unrequited love songs than dispirited rants. If you're wondering how she'll translate those layers live, note the Boss Loop Station beneath her boots. She's not afraid to use it.