- divergence_tolerance was loaded from config but diff_flow_versions
never consulted it, so structural_divergence was always plain
sequence-equality regardless of the configured tolerance. Now
actually applied per design.md D4.
- The skill-catalog-subscription isolation guard test asserted
'skills.catalog' not in sys.modules, which is vacuously true since
that module doesn't exist anywhere yet. Replaced with a real check
against store.py's actual imports.
openspec: skill-versioning capability, archived change skill-learning-runtime
q792602257