embabel realms link <directory>

Point the appliance at the directory your realm checkouts live in — the parent, so adding another realm is a git clone rather than a change to any config.

The path is checked before it is written: one that does not exist, is not readable, is a realm rather than a directory of realms, or is somewhere Docker Desktop does not share, is refused with the reason. What it found is printed.

  Realm checkouts: /Users/you/dev
  4 realms visible: realm-esg, realm-github, realm-legal, realm-stripe

The mount is read-only, by design. You edit on the host — where your editor, your coding agent and your git remote already are — and the appliance only reads. A world then loads one by path instead of by repo:

# config/realms.yml, in the world
- name: esg
  path: /realms/realm-esg

One consequence to know rather than discover: a realm’s declared npm/wasm build runs as part of cloning, so it never fires for a local realm. A declarative realm needs nothing; a realm with a build step must be built on the host first.