One-install Intercom front door over three bounded domain packs and the existing conversation workflows and task Source. It admits 159 of 161 operations in Intercom's immutable 2.15 first-party schema. The two explicit exclusions are the cross-origin recording redirect rejected by the origin-pinned transport and one Fin Voice route with no documented success contract. The two same-origin export downloads use the engine's 64 MiB content-isolated file capture and return file_ref values. The compatibility root preserves all 46 prior operation IDs and routes, representing 45 unique official operations, while dependencies add the other 114 admitted routes. Every call pins Intercom-Version: 2.15; JSON responses preserve unsafe integers, supported collection contracts auto-page within engine caps, the new domain packs mark sensitive reads sensitive-read, the compatibility root retains its prior read posture, and every mutation remains approval-gated.