In a medium bowl, combine warm water, yeast, and sugar; whisk to dissolve completely and leave for 10 minutes until bubbles form and the surface appears foamy. In a separate large bowl, stir together bread flour, whole wheat flour, salt, rolled oats, sesame seeds, sunflower seeds, and flax seeds until evenly distributed. Add the oil, honey or agave, and the activated yeast mixture to the dry ingredients. Stir with a spatula until the dough begins to come together—it will be very moist—then work it by hand, squeezing and folding until no pockets of dry flour remain. Cover with plastic wrap, a damp towel, or a shower cap and let rest for 15 minutes. Perform four rounds of stretch and folds over the next hour at 15-minute intervals by wetting one hand, lifting a section of dough upward until it resists, and folding it over itself. Rotate the bowl 90 degrees and repeat until a full rotation is complete, then cover and let rest until the next round. After the final fold, cover the dough and allow it to rise until doubled in size—roughly 30 minutes if using rapid rise yeast or about 1 hour with active dry yeast. Grease one or two standard loaf pans (8.5 x 4.5 x 2.5 inches). Turn the dough out onto a lightly floured surface, gently press out excess air with your palm, divide if making two loaves, and shape each piece into a tight rectangle matching the loaf pan’s shape. Roll each portion into a firm loaf and place in the prepared pans, pressing gently to settle the dough evenly. Cover and let proof at room temperature until the tops dome just above the pan edges—this takes about 1 hour for rapid yeast or up to 2 hours for active dry yeast. Preheat the oven to 350°F (180°C). For a glossy finish, whisk an egg with 1 tablespoon of water and brush over the loaf tops, or lightly coat with oil and sprinkle extra oats if desired. Bake on the center rack for 35–45 minutes until the crust turns golden and the internal temperature reads 190–200°F (87–93°C). Transfer to wire racks to cool completely for at least 2 hours before slicing with a serrated knife to maintain a soft crumb. Store fully cooled bread in a plastic bag at room temperature for up to 4 days, or slice and freeze in a freezer bag for longer storage. Toast slices straight from the freezer to refresh. Avoid refrigeration to preserve optimal freshness.