A user asked me a sharp question yesterday: Looking at your extraction pipeline, pdfjs + geometryWorker + lattice + visualGridMapper, what makes this any different from any other extraction approach for frontend only, no backend or compiled engine? It's the right question to ask any author of a tool. So I sat down and surveyed the space honestly. What I found was more interesting than my gut answer. The pipeline isn't different because of clever algorithms. The lattice reconstruction is the same lattice reconstruction every server-side tool uses. The KD-tree proximity is a textbook nearest-neighbor query. Y-band paragraph clustering is in a 1996 paper. The math is borrowed. What's different is the quadrant of the design space the pipeline occupies, and the architectural commitments it took to land there. This post maps that design space. It catalogs what's already in each cell, identifies the empty one, and explains why it stayed empty long enough for a niche to form. 1.…