BioSwitch-K2 is a conceptual Digital Twin designed to investigate detectability bias in temperate exoplanets orbiting M-dwarf stars, inspired by the debated case of K2-18b. While such planets may satisfy physical conditions for habitability, atmospheric biosignature detectability depends not only on biological productivity, but also on stellar radiation environments and instrumental sensitivity.

The model couples biomass growth, biosignature gas production, UV-driven atmospheric destruction, and a detection threshold parameter into a simplified computational framework. By exploring parameter space, the system reveals three distinct regimes: no life, detectable life, and a stable Hidden Life regime.

In the Hidden Life regime, biomass remains dynamically stable while atmospheric gas concentrations fail to exceed instrumental detection limits due to enhanced UV suppression. This demonstrates that non-detections in M-dwarf systems cannot be directly interpreted as absence of life.

BioSwitch-K2 highlights the importance of distinguishing between habitability and detectability and provides a structured framework for evaluating potential false negatives in exoplanet biosignature searches.