STA for Physical AI: Safe-Stop Authority, Actuator Commitment, and Minimal-Risk Intervention

This record is Paper 4 of the Signal-Time-Authority (STA) Series. Paper 4 extends the STA pre-commitment controllability framework to physical and embodied AI systems. It focuses on actuator commitment, time-to-impact, physical authority, safe-stop policy, fallback controllers, minimal-risk intervention, shutdown-induced harm, and domain standards boundaries. Paper 1 introduces the STA framework: https://doi.org/10.5281/zenodo.19980763 Paper 2 provides staged C++17 synthetic toy-simulation evidence: https://doi.org/10.5281/zenodo.19984104 Paper 3 specifies authority governors and runtime deployment architecture: https://doi.org/10.5281/zenodo.19984352 This paper does not claim that a kill switch is sufficient for safety. Instead, it argues that physical AI requires domain-configurable safe-stop authority, validated fallback behavior, and harm-aware intervention policies. This is a PublicRelease v1.0 record.