Earth observation models increasingly provide semantic maps, land cover/land use products, and time series for monitoring and reporting. Yet the local reliability of pixel- or object-level predictions is often communicated only indirectly via global accuracy metrics or single-signal uncertainty layers. HELIX-Trust is a model-agnostic post-hoc approach that analyses the spatio-temporal behaviour of prediction outputs and derives a multi-dimensional trust signature for each spatial unit. The signature captures output precision, stability across variants, temporal and spatial coherence, and process plausibility under contextual priors. The result is an interpretable, spatially explicit diagnostic layer supporting targeted inspection, validation, and trust-aware summaries of EO prediction products.