Define AMP-RTC call state machine, federation and multi-device arbitration #23

Scope

Define deterministic terminal transitions, timeout/cancel/accept races, first-answer-wins authority, cross-provider correlation and failure recovery. Acceptance: state transition table and replay/race tests with independent provider implementations.

Architecture

AMP is signed signaling/control; media is separate and provider-neutral. Initial goal: Lola calls an iPhone without PSTN.

Review gates

Validate the hypothesis at the stated checkpoint before proceeding; retain a rollback/feature-flag path.