Bring a large pot of water to a boil for the pasta.
In a large, deep skillet, heat the oil, two turns of the pan, over medium-high. When the oil ripples, add the pancetta and render for 2 to 3 minutes. Add the shallots, garlic, chiles and thyme. Season with salt and pepper and stir for 2 to 3 minutes. Add the vermouth and cook until the liquid has reduced by half, about 5 minutes. Swirl in the butter, then reduce the heat to low to keep the sauce warm while the pasta cooks.
Salt the boiling water; cook the pasta to just shy of al dente. Ladle out about a cup of the pasta cooking water and add it to the sauce along with the crabmeat and lemon zest and juice. Drain the pasta and add it to the sauce. Toss with tongs for 1 to 2 minutes for the pasta to finish cooking and to allow the flavors to be absorbed. Toss in the parsley and chives; season.