Cook pasta: boil capellini in well-salted water 2 to 3 minutes until just barely al dente. Reserve 1/4 cup pasta water. Drain and rinse under cold water. Transfer to a large bowl.
Make dressing: whisk olive oil, lemon juice, lemon zest, garlic, red pepper flakes, salt, and pepper. Taste and adjust.
Dress pasta: pour two thirds of the dressing over cooled pasta, toss well. If sticky, add a splash of pasta water and toss again.
Add ingredients: add cherry tomatoes, parsley, and basil. Toss gently.
Finish: pour remaining dressing over top, toss once. Scatter Parmesan and pine nuts if using.
Chill and serve: refrigerate 20 to 30 minutes. Taste before serving and adjust with lemon, salt, or olive oil.