The night before mixing, combine the water, active starter, and all-purpose flour in a clean jar or container. Stir until no dry spots remain. Let sit at room temperature for 10 to 12 hours until more than doubled.

In the bowl of a stand mixer fitted with the dough hook, combine the sourdough build, warm coffee, bread flour, cocoa powder, light brown sugar, and salt. Mix on low until combined, then increase to medium and mix for about 5 minutes until the surface transforms from mottled to smooth and elastic. The dough will remain slightly sticky.

Add the pecans and chocolate. Mix on low until incorporated.

Lightly oil a medium bowl and scrape the dough in. Cover with plastic wrap and proof at room temperature (not a warm oven or proof box) for about 1 hour.

With lightly oiled hands, fold the dough: slide your fingers under one side, stretch it up, and fold it over itself. Rotate the bowl 90° and repeat around all four sides. Cover and continue bulk proofing for about 3 more hours, until the dough has visibly doubled.

Dust the top of the dough with bread flour. Turn it out onto a lightly floured surface. With floured hands, fold each corner into the center, rotating the dough between folds so you are always folding toward yourself. Use a bench scraper in one hand and your other hand as a guide to shape the dough into a round. Flip seam-side up into a generously rice-floured banneton, cover with plastic wrap, and refrigerate overnight.

After 16 to 18 hours, place a Dutch oven with its lid inside the oven and preheat to 425°F.

Cut a piece of parchment just larger than the Dutch oven base. Loosen the edges of the dough with floured fingers, then turn it out onto the parchment. Score the top with a razor blade at a 45° angle, using a square pattern with overlapping edges to encourage upward rise.

Carefully remove the Dutch oven from the oven, lift the lid, and lower the dough (using the parchment) into the pot. Replace the lid and bake for 20 minutes.

Remove the lid, lower the oven temperature to 400°F, and bake for an additional 20 minutes.

Remove the loaf from the Dutch oven and cool completely on a wire rack before slicing with a serrated knife.