In a stand mixer fitted with a dough hook, mix the water, yeast, and honey. Let stand until foamy, about 6 minutes.
Add the flour, salt, egg, 2 tablespoons sugar, and 4 tablespoons olive oil. With the mixer on low, beat until the dough is nearly completely smooth; it will be sticky and soft. Scrape down the bowl and cover with plastic wrap. Let rise in a warm spot until doubled, 45 minutes to 2 hours, depending on the warmth of your kitchen.
Punch the dough down gently, just to deflate it, scrape the sides and cover it with plastic wrap. Let rise until doubled, about 45 minutes.
Meanwhile, in a small bowl, mix the grapes with the remaining 1 tablespoon sugar. Coat a 15- by-10-inch rimmed jelly roll pan with 2 tablespoons oil. Scrape the dough onto the oiled baking sheet and stretch it out with your fingers, almost fitting the inside of the pan.
Let the dough rise, uncovered, until it’s just above the edge of the pan in places (it won’t be evenly risen), about 1 hour. Heat the oven to 400°.
Gently dimple the dough all over with your fingers. Scatter the grape halves and any juices from the bowl over the dough. Sprinkle with the rosemary needles, inserting a few small sprigs into the dough. Drizzle with the remaining 2 tablespoons olive oil. Sprinkle with the sugar and salt topping.
Bake 20 to 25 minutes, until puffed and browned. Cool about 10 minutes in the pan then transfer to a wire rack or cutting board. Serve warm or at room temperature.