Crisp kirby cucumbers will stay firm and crunchy when mixed in this salad.
In a small saucepan, bring 3/4 cup water, salt, and pepper to a boil. Stir in couscous, shallot, and raisins; remove from heat. Cover; let stand until couscous has absorbed water and is tender, 5 minutes.
In a large bowl, whisk together lemon juice and olive oil; season with salt and pepper. Add chickpeas, couscous mixture, and cucumber; toss to combine. Refrigerate in a covered container until ready to serve.