Classify remaining D&D producer diagnostics

internal/modules/dnd/shared/diagnostics/diagnostics.go

@@ -47,6 +47,33 @@ func Collect(findings []contracts.Warning, disposition contracts.DiagnosticDispo
 	return collector.Diagnostics(), nil
 }
 
+// NormalizationDiagnostics classifies deterministic normalization findings as
+// observations, except for explicitly identified unresolved-quality findings.
+func NormalizationDiagnostics(findings []contracts.Warning, advisoryReasonCodes ...string) ([]contracts.ProducerDiagnostic, error) {
+	advisoryReasons := make(map[string]struct{}, len(advisoryReasonCodes))
+	for _, reasonCode := range advisoryReasonCodes {
+		advisoryReasons[reasonCode] = struct{}{}
+	}
+	observations := make([]contracts.Warning, 0, len(findings))
+	advisories := make([]contracts.Warning, 0)
+	for _, finding := range findings {
+		if _, advisory := advisoryReasons[finding.ReasonCode]; advisory {
+			advisories = append(advisories, finding)
+			continue
+		}
+		observations = append(observations, finding)
+	}
+	diagnostics, err := Collect(observations, contracts.DiagnosticDispositionObservation, contracts.DiagnosticCategoryNormalization)
+	if err != nil {
+		return nil, err
+	}
+	qualityDiagnostics, err := Collect(advisories, contracts.DiagnosticDispositionAdvisory, contracts.DiagnosticCategoryDataQuality)
+	if err != nil {
+		return nil, err
+	}
+	return append(diagnostics, qualityDiagnostics...), nil
+}
+
 func Truncate(value string) string {
 	runes := []rune(value)
 	if len(runes) <= MaxDisplayedRunes {