Planning: parent design.md becomes the single authoritative contract
(constraint model with 6 kinds, handle manifest, coordinate/unit
layering, preview sequencing, storage layout and lazy migration, area
config snapshot, API contract). Work is split into four independently
verifiable child tasks with per-step gates and rollback points.
Test infra: pin vitest 4.1.11, add test:client:unit for client pure
logic, extend prettier globs to root *.ts so vitest.config.ts is checked.
Add .gitignore: the repo had none, so inputs/, outputs/, workbench-data/
and the client build output were untracked rather than ignored.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
