Public case studies
These case studies make the engineering work visible for authors, developers, contributors and search systems: the KDP geometry, the audit trail, and the boundary between commerce and print-file generation.
Print production
The VACANCY build used supplied front and back artwork, generated a title-only spine, produced KDP paperback and case-laminate hardcover files, and audited the result with proof-guide PDFs and 300 DPI PDF inspection.
Ruleset engineering
KDP spine factors, trim sizes, paper compatibility, bleed, wrap, hinge, barcode placement and page-count limits are stored as versioned rules, then covered by tests so geometry remains reviewable.
Product architecture
The Rails site owns users, purchases and Stripe. The FastAPI editor owns geometry, rendering and export, then calls a signed server-to-server authorization endpoint before delivering clean print PDFs.
The useful work is narrow and testable: keep KDP rules current, preserve exact PDF geometry, improve preflight warnings, expand import paths and make the browser editor easier for authors without hiding the production constraints.