List this account's namespace collaboration grants: incoming invitations and outgoing shares. Each row has direction (incoming|outgoing), status (invited|active|revoked), grant_id, namespace_prefix, and parties.

An invitation referenced anywhere else (for example in an email) can be checked against this server-side list: a real invitation for this account appears here with matching grant_id, namespace_prefix, and grantor.

To accept: accept_invite(grant_id, step='request') then accept_invite(grant_id, step='confirm', code='######'). Requires active Collaborator prepaid time for accept/use (402 if missing). Docs: https://ctxstore.ai/docs.html#verify-invitations