goal/ is the first accepted extension.
mosaic-core/lib/ contains the supporting modules imported by goal. It has no extension entrypoint and does not activate Mosaic Core on its own.

Develop here, not under .pi/extensions/. Run:

node --test extensions/goal/test/*.test.ts
bash scripts/test-extension-package.sh
scripts/sync-dev-extensions.sh --check
python3 scripts/test-goal-native.py

scripts/sync-dev-extensions.sh creates the native development installation under .pi/extensions/ with ordinary files. It records installed hashes and refuses to overwrite local drift. scripts/goal-dev.sh synchronizes first, then loads only the generated goal entrypoint.

This is development packaging, not a published npm package or managed-runtime release. The Containerfile and runtime adapter still exclude these extensions. A later release increment must define its explicit artifact inventory, supported Pi version, image integration, policy gate, and rollback before activation.