The cover nobody looked at
- Channels affected
- 3Both Kindle editions and our own shop
- What had been checked
- everythingDimensions, filename, checksum, file size — everything but the image
- Inside the EPUB
- correctA different file from the same folder was uploaded
- Found by
- the founderBy looking at the finished product page, not by any check
On 2 September 2026 a book stood in two Kindle editions and in our own shop — carrying the cover of a different title.
The uncomfortable part is not the mistake. It is everything that had been correct beforehand.
What had been checked
The file had the right dimensions. It had the right name. It sat in the right folder. Its checksum was recorded, its size plausible. Every one of those checks was green, and every single one of them was true.
None of them answers the question that mattered: is the right book on the picture?
You check an image by looking at it. Dimensions, filename and checksum say nothing about what it shows.
The second part, which is worse
The delivered EPUB carried the correct cover inside. So it existed, it had been built, it was right. What got uploaded was nonetheless a different file from the same folder — a sibling that looked just like the one we were after.
Check the item that actually goes out, not its sibling.
What we changed
Four things, and only one of them is a check.
- A record of provenance. The build now writes a manifest listing the role, checksum and key figures of every file it produces. That makes is this the right file answerable.
- A gate instead of a rule. Before an upload, a folder is created containing only the files for that one channel — rebuilt on every run, and not created at all if the checks come back red. Uploads happen from there and nowhere else. That is the real safeguard: nothing wrong is offered in the file dialogue any more.
- An archive, because the build is not reproducible — what sits in the shops under an ISBN cannot be rebuilt (its own entry follows).
- Something that actually looks. A check now presents the cover, the print jacket and every described image to a model and holds the answer against the specification: title, genre, author, series. If it fails, it reports “not checked” — never green.
The first three all answer only is this the right file. The fourth is the only one that answers is the content right.
And a punchline about ourselves
On its first live run, that check refuted an image description we had derived from the source text instead of verifying against the picture.
So the rule applies to whoever writes it down, too.