Reuse comes only from a tree receipt evaluated now, with a bundle produced
on the gated tree, the current execution identity and an unmoved, known
predecessor head. Each lane prints reusable/rerun/not-reusable; REGATE:
not-needed needs stamp-only, every bundle and --require lane reusable (a
stamp-sensitive lane reruns) and a finished migration lookup. Migration
numbers the branch adds are checked against the base tree and every other
open PR (gh pr list --limit 1000; 100-file lists refetched with gh api
--paginate); any lookup that cannot finish is unknown and blocks
not-needed (MIGRATION_COLLISION). Bare --against routes to the verb.
docs/pregate.md gains the regate section and the gbrain worked configs.
Co-authored-by: capy-ai[bot] <230910855+capy-ai[bot]@users.noreply.github.com>
