Codifies the interface between core and modules: the four registries
(delivery actions, inbound gate, response dispatcher, MCP tool
self-registration), default modules (typing, mount-security),
guarded-inline fallbacks, MODULE-HOOK skill-edit markers, and module
migration naming.
Authoritative reference for downstream extraction PRs and install
skills. See REFACTOR_PLAN.md for broader context.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
