first commit

libs/web/tracker/application/src/lib/notifications.ts

@@ -0,0 +1,25 @@
+/** Outbound port: tell the user how a command went (implemented with toasts by the app). */
+export abstract class Notifications {
+  abstract success(message: string): void;
+  abstract error(message: string): void;
+}
+
+/** Message of a failed GraphQL/HTTP call, for the user. */
+export function describeError(error: unknown): string {
+  if (
+    error &&
+    typeof error === 'object' &&
+    'errors' in error &&
+    Array.isArray((error as { errors: unknown[] }).errors)
+  ) {
+    return (error as { errors: { message: string }[] }).errors
+      .map((e) => e.message)
+      .join('\n');
+  }
+  return error instanceof Error ? error.message : String(error);
+}
+
+/** The read model is eventually consistent: right after a command, a query may 404 for a few ms. */
+export function isNotFound(error: unknown): boolean {
+  return /not found/i.test(describeError(error));
+}