Heat oven to 350°F. Line two baking sheets with parchment.
Whisk flour, baking powder, baking soda, and salt in a medium bowl.
Cream butter and 1 cup sugar in a large bowl until pale and fluffy, about 2–3 minutes.
Beat in egg, yolk, vanilla, lemon zest, and lemon juice until smooth.
Mix in dry ingredients on low just until a soft dough forms; avoid overmixing.
Chill dough 10–15 minutes if sticky to make scooping easier.
Scoop dough into 1½-tablespoon balls. Roll each in the remaining sugar to coat.
Arrange on sheets 2 inches apart. Gently flatten tops slightly with your fingers.
Bake 9–11 minutes, until edges are set and centers look pale and soft.
Cool on the sheet 5 minutes, then transfer to a rack to finish cooling.