It does not slice or stack: it packs, the strands holding together loosely and carrying a film of the fat they were cooked in, and that texture sets the whole sandwich. Confit de canard is duck leg salted, then cooked slowly submerged in rendered fat until it is tender enough to pull off the bone in moist, savory threads. Shredded into a sandwich it does not slice or stack: it packs, the strands holding together loosely and carrying a film of the fat they were cooked in. The build is a length of baguette, little or no added butter, and warm shredded confit pressed along the bread, often with the duck skin crisped and torn back in.
The logic follows from the fat. Because the meat is already rich and slightly salty from the cure, the sandwich needs no spread to carry it and instead needs something to cut it: a smear of mustard, a few cornichons, a spoonful of onion or fig confit, sometimes a leaf of frisée. The shredded texture means the filling settles into the crumb rather than sitting on top of it, so the bread has to have a firm crust to keep its shape while the duck fat softens the interior from within. Crisping the skin and folding it back through the meat adds the one textural contrast the soft strands lack, and it is worth the extra step. The discipline is to add a single sharp counterweight and stop, since the confit is intense enough that a busy build buries it.
The bread needs a real crust to stand up to a warm, fat-rich filling, and the duck is best gently warmed so the fat loosens and the strands stay moist rather than congealing. Served cold, the fat sets and the meat tightens, which is why it is usually assembled close to the time it is eaten.
Variations stay on the southwestern duck and preserved-meat shelf: a slice of magret fanned over the confit for a firmer, leaner counterpoint, a smear of duck rillettes for a fully spreadable version of the same animal, or a thin layer of foie gras under the meat when the sandwich is meant to be richer still. Each is a different handling of duck on the same bread. It belongs with the spread and terrine sandwiches the catalog groups under Baguette Pâté, and its specific contribution is meat preserved in its own fat that packs into the bread and asks only for a sharp note against it.