A receding solution front crosses the square from top edge to left edge, advancing in long straight facets instead of a smooth curve, as if the front grew face by face. The top-right basin stays dark and quiet while bands of dots and dashes trace the faceted shoreline, growing denser and heavier toward the bottom-left into a saturated mass with a paper slash. The facet joints gather slightly more deposit where the front changed direction.
One image rather than a generative program: the piece above is the work, and the code that drew it is there to read.