Build presence-aware execution targets from effective configuration

internal/backend/registry.go

@@ -35,6 +35,23 @@ type Registry struct {
 	backends map[string]domain.Backend
 }
 
+// NewEffectiveRegistry stores already-validated effective backend definitions
+// under their exact configuration keys. Configuration validation and
+// normalization precede this ownership boundary.
+func NewEffectiveRegistry(definitions map[string]domain.Backend) (*Registry, error) {
+	registry := &Registry{backends: make(map[string]domain.Backend, len(definitions))}
+	for id, definition := range definitions {
+		params, err := jsonvalue.CopyMap(definition.ExtraParams)
+		if err != nil {
+			return nil, fmt.Errorf("backend %q extra parameters: %w", id, err)
+		}
+		definition.ID = id
+		definition.ExtraParams = params
+		registry.backends[id] = definition
+	}
+	return registry, nil
+}
+
 // NewRegistry constructs a registry containing maintained definitions followed
 // by consumer additions. Every ID must be unique across both groups.
 func NewRegistry(maintained, additions []domain.Backend) (*Registry, error) {