Shipped plans

The plans that shipped under the old rule, when a plan was archived rather than folded into its PR. Each maps onto a merged pull request, which carries the same design plus the diff that implemented it.

These are working documents, not testimony: editable, trimmable, deletable. Whatever a plan's PR already says is duplication. What earns keeping is the part no PR and no commit holds, the alternatives considered and rejected.

From now on a plan ends at its PR and never lands here (CLAUDE.md, Branch), so this folder stops growing.