Why: the library now makes precedence, memory tiers, and lesson
mechanization explicit; the composition must pin the revision and register
how its layers map onto the new rules.
Evidence: guidelines PR#3 (ed2af3e) and documents PR#4 (2205138) merged;
make test on this branch per the gitlink rule.
Impact: gitlink advances; adoption registers the hierarchy/memory rows as
manual-with-existing-artifacts. No code change.
Refs: policy/adoption.md; docs/records/2026-09-30-history-migration-sha-map.md
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