Appendix — Book usage (live) #

State of the art captured in 2026-07 · last revised 2026-07-29 · history and expiration log

A book that teaches verification (ch. 11) and interface observability (ch. 13) should be able to answer a question about itself: how is this book used? This page answers it — live.

What is measured (and what is not) #

Since edition 0.49, the site records aggregate navigation: which page was visited, how many times, by anonymous sessions — and only after the reader accepts the telemetry notice (the banner on the first visit). Nothing beyond that:

• We do not collect IP, user-agent, name, email or any personal data;
• the session is a random identifier generated by the browser, erasable by the reader themselves (the companion's /limpar command removes everything from the session — the right to be forgotten);
• the panel below consumes a strictly aggregated projection (total and per-page counts) — there is no public endpoint with individual data.

The live panel #

(The numbers above exist only in the online version — in the PDF this island is omitted by definition.)

What it is for #

This panel is the same input that drives the living book's cadence (ADR 0007, in Portuguese): chapters getting more reader attention take priority in the quarterly revision window, and ignored pages raise the right editorial question — is it lacking promotion, or lacking a rewrite?

It is also a miniature demonstration of what the book preaches: instrumenting is the cheap half of verification — the expensive half is deciding what to do with the number. The decision record lives, as always, in the History (in Portuguese).