Added just minutes before serving, thinly sliced squash melts into the pasta without losing its shape and texture. Use a mandoline to achieve wafer-thin slices
Cook pasta in a large pot of generously salted water until very al dente (about 2 minutes less than package directions). Drain pasta, reserving 3/4 cup cooking liquid. Set pasta and cooking liquid aside.
Heat 1 tablespoon oil in a large, deep skillet over medium-high until shimmering. Add sausage in 1-inch clumps, and cook, undisturbed, until browned on bottom, about 3 minutes. Stir and cook, breaking up sausage with a wooden spoon, until almost cooked through, about 2 minutes. Drain and discard drippings, reserving cooked sausage and 1 tablespoon drippings in skillet.
Add harissa to skillet; cook over medium-high, stirring constantly, 30 seconds. Add wine, stirring and scraping up any browned bits from bottom of skillet. Cook, stirring occasionally, until slightly reduced, about 2 minutes. Stir in tomatoes, salt, cooked pasta, and 1/2 cup reserved cooking liquid. Cook, stirring constantly, until a creamy sauce forms and coats pasta, about 3 minutes, gradually stirring in remaining 1/4 cup cooking liquid as needed to reach desired consistency. Remove from heat.
Scatter sliced squash and mint over pasta. Drizzle with remaining 1 tablespoon oil, and toss to combine. Let stand until squash is slightly wilted, about 2 minutes. Season with harissa and salt to taste. Divide pasta among bowls, and top evenly with feta; garnish with sliced mint.
Spicy Southern Italian red.