ADR 0002: google-antigravity SDK is the primary gateway

Status

Accepted (2026-08-13).

Context

Two transports exist: the preview SDK and the agy CLI.

Decision

AgentGateway is the port. --gateway sdk (default) uses google.antigravity.Agent. --gateway cli is a secondary adapter behind the same port. Vendor types never leave infrastructure/.

Consequences

Recorded in architecture §19. Changing this ADR requires a new numbered record, not a silent edit of the classifier or ports.