A plugin is the seed's hard-substrate cell — one concern, its own hidden state, a small published surface. Editing it is heavier than any project edit, because a code regression is substrate-wide. So self-modification runs through a lock ceremony: one plugin unlocked at a time, [PLUGIN-LOCK] to open, lock-cmd to preserve or safe-lock to auto-revert on a failed test, and a 3-file floor when a brand-new plugin is born. Each card is one focused idea, with a clean diagram you can hover and click.
The cell is the unit; the lock ceremony is what makes a cell safe to change.