ADR 0009 — Shared pages are core, not an add-on

Status: accepted · 2026-09-13

Context. The earlier private design had a data model for a moment shared between two people but no interface and no task for it.

Decision. The circle — a page handed to a named person, who hands one back — is one of the three core ideas (VISION.md) and gets a user interface and a bundle format in the roadmap (phase 3), before books and publishing.

Consequences. The shared-page bundle format is specified before any transport is chosen, so two logbooks can exchange a page by file first.