kdp-publishing

Claude Code plugin for producing a print-ready Amazon KDP paperback with Typst — trim geometry, a full-wrap cover, mechanical pre-flight, and an upload folder.

/plugin install kdp-publishing@danielrosehill

It does not write your book

This plugin is production, not authorship. It takes a manuscript you already have and turns it into two PDFs a printer will accept.

It does not draft chapters, generate blurbs, invent keywords or write your description. Nothing in it assumes the text was written by an AI, and nothing in it works better if it was. If you typed every word yourself, this is aimed at you.

That is a deliberate line. Typesetting and copywriting are different jobs with different failure modes, and the tools that bundle them tend to be good at neither. Ask Claude to help with your blurb whenever you like — just not as a side effect of building a book.

Why it exists

The expensive mistakes in print-on-demand are the ones that produce a successful-looking build. Typst exits 0. The PDF opens. KDP accepts the upload. You find out three weeks and one print charge later, when the proof copy arrives.

Three of them, all handled here:

A cover built from a stale page count. Spine width is page count × paper caliper, so a cover built before the interior was finished has a spine that does not match the book — the spine type sits off-centre, or the title wraps onto the front face. Nothing on screen reports it.

So the cover is built last, and from the interior. build-cover.py refuses to take a page count and runs pdfinfo over the PDF you actually built. kdp-package.py then measures the finished wrap, subtracts both faces and both bleeds, and compares what is left against the spine this extent needs — the same fact from the opposite direction. A stale cover has to defeat both.

A missing glyph. Typst does not warn when a character has no glyph in the requested font. It falls back through the system font list, renders it in some other face, and exits 0. On a machine with different fonts installed, the same source produces a different book. Pre-flight enumerates every codepoint in the source, confirms each survives into the PDF, and lists what actually got embedded.

A gutter set for the wrong extent. KDP's minimum inside margin is tiered by page count, so a book that grows past 300 pages needs wider margins than the same book at 299. Under it, text is swallowed into the bind on every page — and a PDF viewer will never show you, because it does not bind anything. Margins here are derived from the measured first-pass extent, not from an estimate.

The principle underneath all three: check the artifact, not the signal that stands in for it.

Standard trim sizes, by default

KDP splits paperback trims into standard and non-standard. Standard sizes are available in every marketplace, are what the print-cost tables are quoted against, and are the only ones some expanded-distribution channels accept.

So the plugin steers to KDP's US standard list — 5×8, 5.5×8.5, 6×9, 7×10, 8.5×11 and the rest — and warns on anything else. A non-standard trim still builds correctly; it just has to be a decision rather than a typo.

The pipeline

/kdp-init       choose a standard trim and paper, write book.toml, copy templates
       ↓
/kdp-build      typeset the interior — gutter-aware margins, even page count
       ↓
/kdp-preflight  trim, parity, gutter, font round-trip, listing limits
       ↓
/kdp-cover      full wrap, spine measured from the built interior
       ↓
/kdp-package    dist/kdp-upload/ — PDFs plus what goes in which form field

Each step reads book.toml, the single source of the book's identity and print settings. The title page, the cover and the KDP listing all derive from it, so they cannot disagree — which matters because KDP locks the title field 72 hours after publication and requires it to read exactly as the cover prints it.

Skills

• kdp-print-geometry — trim, paper, spine, margins, bleed, wrap dimensions
• kdp-typeset-interior — Typst interior, and the Typst behaviours that fail silently
• kdp-cover-wrap — the full wrap, and three layout rules that are each a lost proof copy
• kdp-preflight — what to verify, and what no script can verify for you

Reference

reference/ carries KDP's own figures with the date each was verified and the URL it came from. KDP changes these without notice and without a changelog, so quote the date alongside the number rather than presenting it as current.

• trim-sizes.md — standard trims, paper calipers, page-count limits
• margins.md — the tiered gutter table, outside margins, bleed
• cover-spec.md — wrap maths, safe zones, spine text, the barcode corners
• listing-limits.md — field limits and the 72-hour title lock

Requirements

• typst on PATH
• poppler-utils — pdfinfo, pdftotext, pdffonts
• Python 3.11+ (for tomllib)

No API keys, no network calls, no accounts. The whole thing runs offline.

Scripts

They work standalone if you would rather not go through the commands. Each finds the nearest book.toml by walking up from the working directory.

python3 scripts/kdp_geometry.py --list-trims
python3 scripts/kdp_geometry.py --pages 398 --trim 6x9 --json
python3 scripts/build-interior.py
python3 scripts/build-cover.py
python3 scripts/preflight.py --json
python3 scripts/kdp-package.py

kdp_geometry.py is the single source of every number. Nothing else computes a spine width, a wrap dimension or a gutter minimum on its own.

Provenance

Extracted from two books actually printed this way — a 398-page generated reference index and its companion technical volume. Both validated on KDP first time. The checks in here exist because something went wrong once, not because they seemed like good practice.

Licence

MIT.