Guide

What the library does, explained in plain language for the Product Owner and, later, for users. No formula without a sentence that says what it means; no term without a definition or a link to the glossary. Each page ends with how to try it in the playground and the validation by the Product Owner.

Written at the end of each feature (VAL, demo page) and of each epic (REV, epic report), ADR-0023. Category: explanation (REF-DIATAXIS); the API reference stays austere.

Writing rules

1. Start with what the user sees, then why, then how — one idea per paragraph.
2. Explain each technical word the first time: "a fillet is the small arc that replaces a sharp corner".
3. Numbers from the playground rather than symbols: "a 100 × 25 rectangle with radius 100 gets radius 12.5".
4. A picture (SVG produced by the library, or a sketch) for every geometric idea.
5. Say the limits: what the feature does not do yet, and which feature will.
6. The guided test is a few short steps, each with what to do and what to see; it lives in the playground for the feature being validated only. The Product Owner says what they see; the agent records the result and the remarks in neutral words (docs/conventions/writing.md).
7. At the epic review, every step of the epic comes back at once: ?guide=epic in the playground's address.

Pages

Page	Content
F01 — A rectangle with rounded corners	rounding corners, the radius reduced to fit, the guided test
F02 — A regular polygon with rounded corners	the polygon fitted in its box, the inscribed circle, sizes, the guided test
F07 — A polygon anchored in its box	the nine anchor buttons, the intent kept, rounding inwards, the guided test
F03 — A rounding for each corner	points mode, point 1 and 2, choosing corners, Mixed, the guided test
F09 — The rectangle, a free shape you can stretch	points in a box of their own, stretching without loss, the guided test
F08 — Moving, adding and deleting points	converting a polygon, typing x and y, a point in the middle, deleting, the guided test
F04 — Turning a shape by any angle	the angle, the two boxes, the position, editing a turned shape, the guided test
F06 — A polygon stretched to its box	the Stretched to its box check box, rule C in five boxes, the guided test
E01 — Drawing symbol shapes from numbers	the eight features of E01, the words, a user test crossing them, the decisions

Templates: _feature-demo.md, _epic-report.md (not published).