Why: Merge commits share a tree with the pinned feature commit, the import ratchet downloaded modules during CI, and task sync wrote the checkpoint onto the wrong card.
Evidence: check-pins accepts 6c0f1e8 (same tree as Backend squad 8e987bf) and rejects empty-tree 8db069d; both objects stayed local. An empty GOMODCACHE run of lint-boundaries matches the cached go list, 14 pairs. bash -n scripts/task.sh.
Impact: make pin no longer checks out Backend nested core or agent-command, and a failing pin check does not fail the target. task sync writes the branch card or warns. precheck reports completed-but-unarchived cards and card-close branches older than 24 hours.
Refs: feature/agent-stack-r0-r1
Co-authored-by: Cursor <cursoragent@cursor.com>
