DEMO: COSME -- Composable Orchestrated Starlink Mobility Emulation
Low Earth Orbit (LEO) satellite links are pivotal for ubiquitous vehicle connectivity, yet their performance is impacted by a complex interplay of weather, constellation dynamics, and physical obstructions. While individual models for these impairments exist, protocol and application designers lack a unified tool to evaluate behavior under realistic, composed LEO conditions. We present COSME, a route-aware, real-time mobility emulator that integrates multiple impairment models - including obstruction-based loss, constellation-induced jitter, precipitation-driven bandwidth reduction, and packet loss at handovers - into a single framework. By orchestrating Linux network namespaces via tc and netem, COSME enables the high-fidelity playback of merged impairment traces. We demonstrate COSME through five diverse application showcases, highlighting the impact of different congestion control algorithms and transport protocols on LEO connectivity.