Function resolve 

pub fn resolve(
    request: &RealizationRequest,
    requirements: RealizationRequirements,
    capabilities: &RealizationCapabilities,
) -> Result<ResolvedRealization, Diagnostic>

Resolve one request without mutating the semantic model or silently falling back.

Errors

Returns EQ0807 for an unknown default policy version, contradictory plan, or unsupported backend capability. Explicit failures never become defaults.