Add batch distributor notification state artifacts

internal/state/filesystem.go

@@ -141,6 +141,33 @@ func (s *FilesystemStore) SaveDistributorNotification(_ context.Context, resolve
 	}, artifact)
 }
 
+func (s *FilesystemStore) BatchDistributorNotificationPath(ref BatchDistributorNotificationRef) (string, error) {
+	if s == nil {
+		return "", fmt.Errorf("state store is required")
+	}
+	if err := validateBatchNotificationRef(ref); err != nil {
+		return "", err
+	}
+	localDate := ref.StartedAt.In(ref.Location).Format("2006-01-02")
+	return s.join(s.notificationsDir, "batches", ref.Batch, localDate, ref.BatchRunID+".distributor.json"), nil
+}
+
+func (s *FilesystemStore) SaveBatchDistributorNotification(_ context.Context, ref BatchDistributorNotificationRef, artifact BatchDistributorNotificationArtifact) (string, error) {
+	path, err := s.BatchDistributorNotificationPath(ref)
+	if err != nil {
+		return "", err
+	}
+	if artifact.SchemaVersion == "" {
+		artifact.SchemaVersion = BatchDistributorNotificationSchemaVersion
+	}
+	artifact.Batch = ref.Batch
+	artifact.BatchRunID = ref.BatchRunID
+	if err := fileutil.WriteJSONAtomic(path, artifact); err != nil {
+		return "", err
+	}
+	return path, nil
+}
+
 func (s *FilesystemStore) SaveGeneratedTextRaw(_ context.Context, resolved report.Resolved, data []byte) (string, error) {
 	return s.saveResolvedBytes(resolved, func(paths ArtifactPaths) string {
 		return paths.GeneratedTextRaw
@@ -461,6 +488,35 @@ func validateRelativeDir(name string, value string) error {
 	return nil
 }
 
+func validateBatchNotificationRef(ref BatchDistributorNotificationRef) error {
+	if err := validatePathSegment("batch kind", ref.Batch); err != nil {
+		return err
+	}
+	if err := validatePathSegment("batch run id", ref.BatchRunID); err != nil {
+		return err
+	}
+	if ref.StartedAt.IsZero() {
+		return fmt.Errorf("batch started time is required")
+	}
+	if ref.Location == nil {
+		return fmt.Errorf("batch location is required")
+	}
+	return nil
+}
+
+func validatePathSegment(name string, value string) error {
+	if strings.TrimSpace(value) == "" {
+		return fmt.Errorf("%s is required", name)
+	}
+	if strings.ContainsAny(value, `/\`) {
+		return fmt.Errorf("%s must not contain path separators", name)
+	}
+	if value == "." || value == ".." {
+		return fmt.Errorf("%s must be a safe path segment", name)
+	}
+	return nil
+}
+
 func readJSON(path string, target any) error {
 	data, err := os.ReadFile(path)
 	if err != nil {