Add notification toasts and surface persistence failures instead of failing silently

src/app/services/storage-errors.test.ts

@@ -0,0 +1,45 @@
+import { describe, expect, it } from 'vitest';
+import { StorageQuotaError } from '../infrastructure/snippet-store';
+import { storageErrorNotification } from './storage-errors';
+
+describe('storageErrorNotification', () => {
+  describe('a failure the user can fix (storage full)', () => {
+    it('tells them the step to take and carries no diagnostic detail', () => {
+      const n = storageErrorNotification('save', new StorageQuotaError());
+      expect(n.kind).toBe('error');
+      expect(n.title).toBe('Storage full');
+      expect(n.message.toLowerCase()).toContain('delete');
+      // Nothing to report — the fix is in the user's hands.
+      expect(n.detail).toBeUndefined();
+    });
+  });
+
+  describe('a failure the user cannot fix', () => {
+    it('explains a load failure and attaches a reportable diagnostic', () => {
+      const n = storageErrorNotification('load', new DOMException('blocked', 'SecurityError'));
+      expect(n.kind).toBe('error');
+      expect(n.title).toBe("Couldn't open your library");
+      expect(n.detail).toBeDefined();
+      // The diagnostic names the operation and the underlying error.
+      expect(n.detail).toContain('load');
+      expect(n.detail).toContain('SecurityError');
+      expect(n.detail).toContain('blocked');
+    });
+
+    it('uses the right title for a failed save vs delete and includes detail', () => {
+      const save = storageErrorNotification('save', new Error('boom'));
+      expect(save.title).toBe("Couldn't save your changes");
+      expect(save.detail).toContain('save failed');
+      expect(save.detail).toContain('boom');
+
+      const del = storageErrorNotification('delete', new Error('boom'));
+      expect(del.title).toBe("Couldn't delete the snippet");
+      expect(del.detail).toContain('delete failed');
+    });
+
+    it('describes a non-Error throw without crashing', () => {
+      const n = storageErrorNotification('save', 'weird string');
+      expect(n.detail).toContain('weird string');
+    });
+  });
+});