This dough takes a long time to ferment, mainly due to the alcohol in the dough, and possibly also due to the cocoa powder and sugar. At warm ambient temps, e.g. over 78°F, the dough still may need 10-14 hours for the bulk fermentation. With cooler ambient temps, try warming the beer and water to 90°F before mixing if you want to ensure the first rise is done by evening. I suggest a cold final proof in the refrigerator to deepen the flavor, anywhere from 8-16 hours.

The night before mixing the dough, feed your sourdough starter with rye whole grain flour so it ripens by morning. This could be a 1:3:3 ratio of 15 grams sourdough starter, 45 grams water, and 45 grams rye whole grain flour. (You'll have 5 grams extra, which you are welcome to put into the dough.) Also the night before, consider serving yourself or someone else a portion of a porter beer. Reserve 155 grams for the dough, covered and left out to warm up overnight.

In the morning, mix the dough ingredients, minus the chocolate chips, in a large bowl. Use the smalled end of the water range if your bread flour has less than 13.5% protein. Note that regardless of water quantity, the dough is sticky because of the cocoa powder, rye, and sugar, but by the third round of gluten development, it should be manageable. If it's not, add a small amount of flour and reevaluate and the next coil fold.

Over the next two hours, do four rounds of gluten development that are separated by 20-30 minute rests. These are:

Stretching and folding

Laminating to add the chocolate chips, see this video for how to laminate in dough additions

Coil folding to further distribute the chocolate chips

A final round of coil folding

Let the dough rise until it has almost doubled. See the photo gallery for target expansion; the dough domes quite a bit and expansion is difficult to gauge. Beware that the dough will have very little activity for the first 6+ hours. My final dough needed 13 hours in a proofer set to 80°F, and an earlier test dough with only beer for hydration needed almost a full day.

Scrape the dough out of the bowl onto a floured work surface and shape it to fit your proofing basket. Flour the top of the shaped dough and flip it into the banneton seam-side up.

Cover and refrigerate the dough for 8-16 hours. You can bake the dough directly from the refrigerator. Use a layer of parchment paper between the cold dough and the hot baking vessel if it is clay. My dough proofed for 9.5 hours. If you prefer, you can bake the dough the same day by proofing at room temperature for 1-3 hours.

Preheat your oven and baking vessel to 500°F for 30 minutes.

Flip the dough out of the proofing basket and onto a sheet of parchment paper or a silicone bread sling, score, and load into your baking vessel and oven.

Immediately drop the oven temperature to 450°F.

Bake for 45 minutes or until the internal temperature of the bread is over 205°F. Keep the lid on the entire time to prevent the bread from over-browning and the surface chocolate chips from burning. Note the option to briefly remove the lid at the 7-minute mark and re-score the dough along the top of the original cut. This boosts oven spring and score bloom. You can also remove the lid as needed to use a probe thermometer toward the end of the bake.

Let the bread cool for several hours before you slice it unless you don't mind melty chocolate chips smearing throughout the crumb.