8pt font a6paper build is a go. Bottom margin maybe a bit too big, but its getting closer

src/promise.tex

@@ -1,8 +1,10 @@
 % Document Definition
-\documentclass[10pt]{book}
+\documentclass[8pt]{extbook}
 
 % Required Packages
-\usepackage[letterpaper, total={7in, 9.5in}]{geometry}
+% a6paper = 4.1in by 5.8in
+% decent margins would be... leave about 
+\usepackage[a6paper, total={3.3in, 4.6in}]{geometry}
 \usepackage[utf8]{inputenc}
 \usepackage[english]{babel}
 \usepackage{ragged2e}