major introduced by this diff in .changeset/22080-v18-line-opens.md: @objectstack/spec

ADR-0087 exemption (no-migration-prescription): the v18 line's opening marker: Changesets pre mode plus one major on the fixed group, so the train versions 18.0.0-next.N. No authorable key, spelling, export, type or stored shape moves in this diff, and no stored row is read, rewritten or converted; each breaking stage of the line states its own disposition in its own changeset. The other categories are closed on facts: the package publishes (not unpublished); no ADR-0087 id is named or touched (not registered or already-registered); and no TypeScript declaration moves (not runtime-interface-only or type-surface-only).