Add Notarius reference configuration vocabulary

internal/notariusref/selector.go

@@ -0,0 +1,43 @@
+// Package notariusref owns Narratio's Notarius CLI reference-selector
+// vocabulary without depending on Notarius implementation packages.
+package notariusref
+
+import (
+	"fmt"
+	"strings"
+)
+
+// NormalizeSelector validates and normalizes a Notarius v0.6 reference
+// selector. It intentionally validates selector structure only; Notarius owns
+// target, slot, and media compatibility.
+func NormalizeSelector(value string) (string, error) {
+	selector := strings.TrimSpace(value)
+	if selector == "" {
+		return "", fmt.Errorf("reference selector is required")
+	}
+	if strings.Contains(selector, "=") {
+		return "", fmt.Errorf("reference selector must not contain '='")
+	}
+
+	parts := strings.Split(selector, ".")
+	for index := range parts {
+		parts[index] = strings.TrimSpace(parts[index])
+		if parts[index] == "" {
+			return "", fmt.Errorf("reference selector components must not be empty")
+		}
+	}
+
+	switch len(parts) {
+	case 1, 2:
+		return strings.Join(parts, "."), nil
+	case 3:
+		switch parts[1] {
+		case "extract", "merge", "normalize":
+			return strings.Join(parts, "."), nil
+		default:
+			return "", fmt.Errorf("three-component reference selector must use extract, merge, or normalize as its middle component")
+		}
+	default:
+		return "", fmt.Errorf("reference selector must use slot, chunk.slot, lane.slot, or lane.stage.slot")
+	}
+}