CidLink

A CID link as encoded by the AT Protocol data model.

On the wire, a CID link is always a single-key JSON object with the reserved $link key holding the CID string:

{ "$link": "bafkreig..." }

The lexicon spec uses cid-link for this shape. It intentionally differs from a bare cid string so that CBOR/DAG-CBOR round trips preserve the "this is a content-addressed link" signal distinct from an opaque identifier. v1 of this runtime is JSON-only but we keep the distinction so a future CBOR emitter can map CidLink to the CBOR tag-42 link type without touching call sites.