Preheat the oven to 375°F.

Wash the beans well and put them in a large stockpot. Add enough water to the beans to cover by 2 inches and set over high heat. Bring to a boil for 2 minutes, remove from the heat, cover, and let stand 1 hour.

Put the duck sausage on a baking sheet and place it in the oven for 15 to 20 minutes. Remove and let cool. The sausage will not be fully cooked through.

Add the whole onion, whole carrot, two of the thyme sprigs, and three of the bay leaves to the beans. Add more water to the pot to cover again by 2 inches. Bring to a boil, lower the heat, and let simmer until the beans are mostly tender but with still a little bite to them, 50 to 60 minutes.

As the beans cook, put the bacon into a large skillet and place over medium heat. Cook until crispy and transfer the bacon to a paper towel—lined plate to drain. Drain off all but about 1 tablespoon of the bacon fat from the skillet and add the olive oil. Return to the heat and add the diced onion, sliced carrots, and garlic and cook the mixture over low heat for 20 minutes, until the onion begins to turn translucent.

Slice both the duck sausage and the kielbasa on the bias into ½-inch-thick pieces and add them to the vegetable mix. Add the remaining bay leaves and thyme sprigs and cook, stirring, for 5 minutes. Next add the wine, broth, tomato paste, salt, and pepper. Raise the heat to high, bringing the mixture to a boil. Stir well to dissolve the tomato paste and lower the heat. Allow the mix to simmer for 5 minutes.

Remove the whole onion and carrot from the beans and add the vegetable and sausage mixture to the stockpot, leaving the pot on low heat. Stir well and cover. Let the cassoulet simmer for 15 to 20 minutes, or until most of the wine mixture has been absorbed by the beans. Spoon into a casserole dish and serve with crusty baguette on the side.