Camera-based contactless heart rate monitoring offers significant potential for clinical care and longitudinal research, yet estimation often fails in challenging windows containing competing pulse candidates, aliases, or motion artifacts. To overcome this deployment bottleneck, we present VitalsSight, a candidate-aware supervised framework that retains pulse candidates across diverse signal routes prior to selection, thereby preserving critical physiological evidence. In internal subject-disjoint evaluations on the University of Bourgogne Franche-Comté remote photoplethysmography (UBFC-rPPG) benchmark dataset (42 participants, 439 windows), VitalsSight achieved a primary window-level mean absolute error of 1.646 ± 0.051 beats per minute, with consistent error reductions across stress datasets including MCD-rPPG and rPPG-10. Crucially, when encountering real-world deployment boundaries—such as severe low light and source shifts—VitalsSight outputs an evidence packet capturing candidate ambiguity to support a transparent release/review contract. Rather than masking errors through forced automated outputs, this auditable mechanism establishes a safer and more pragmatic foundation for the clinical translation of digital vital sign monitoring systems. Code available at https://github.com/ShikiRyo1/VitalsSight-candidate-aware-rPPG.