Y999 is an offline modular scale lab for layout and print sizes. On SCALE you type width and height, drag the edge factor strip, and the green OUT block updates with the live scaled size, area, and aspect while a geometric preview rectangle grows with the factor. SPLIT cuts any length into equal modules or a golden phi pair. GRID builds a columns-by-rows module map from the same span and shows module size plus cell count. SIZES is a searchable table of paper and screen presets you can apply back onto SCALE in one tap. KEPT stores named runs in local Room so you can reopen, share plain text, or delete. TUNE keeps unit labels and decimal places in SharedPreferences. Everything stays on the phone with no account and no network.
