feat: namespaced localStorage store with export/import

src/core/store.js

@@ -0,0 +1,28 @@
+const PREFIX = 'gmd';
+
+export function createStore(namespace, storage = globalThis.localStorage) {
+  const full = (key) => `${PREFIX}.${namespace}.${key}`;
+  const nsPrefix = `${PREFIX}.${namespace}.`;
+  return {
+    get(key, fallback = null) {
+      const raw = storage.getItem(full(key));
+      if (raw == null) return fallback;
+      try { return JSON.parse(raw); } catch { return fallback; }
+    },
+    set(key, value) { storage.setItem(full(key), JSON.stringify(value)); },
+    remove(key) { storage.removeItem(full(key)); },
+    exportAll() {
+      const out = {};
+      for (let i = 0; i < storage.length; i++) {
+        const k = storage.key(i);
+        if (k && k.startsWith(nsPrefix)) out[k] = storage.getItem(k);
+      }
+      return out;
+    },
+    importAll(obj) {
+      for (const [k, v] of Object.entries(obj)) {
+        if (k.startsWith(nsPrefix)) storage.setItem(k, v);
+      }
+    },
+  };
+}

tests/core/store.test.js

@@ -0,0 +1,40 @@
+import { describe, it, expect, beforeEach } from 'vitest';
+import { createStore } from '../../src/core/store.js';
+
+function fakeStorage() {
+  const map = new Map();
+  return {
+    getItem: (k) => (map.has(k) ? map.get(k) : null),
+    setItem: (k, v) => map.set(k, String(v)),
+    removeItem: (k) => map.delete(k),
+    key: (i) => [...map.keys()][i] ?? null,
+    get length() { return map.size; },
+  };
+}
+
+describe('createStore', () => {
+  let s, storage;
+  beforeEach(() => { storage = fakeStorage(); s = createStore('afterimage', storage); });
+
+  it('round-trips JSON values under a namespaced key', () => {
+    s.set('clock', { startedAt: 5 });
+    expect(storage.getItem('gmd.afterimage.clock')).toBe('{"startedAt":5}');
+    expect(s.get('clock')).toEqual({ startedAt: 5 });
+  });
+
+  it('returns fallback for missing/corrupt keys', () => {
+    expect(s.get('missing', 42)).toBe(42);
+    storage.setItem('gmd.afterimage.bad', '{not json');
+    expect(s.get('bad', 'fb')).toBe('fb');
+  });
+
+  it('exports only its namespace and imports back', () => {
+    s.set('a', 1);
+    storage.setItem('gmd.other.z', '9');
+    const dump = s.exportAll();
+    expect(Object.keys(dump)).toEqual(['gmd.afterimage.a']);
+    const s2 = createStore('afterimage', fakeStorage());
+    s2.importAll(dump);
+    expect(s2.get('a')).toBe(1);
+  });
+});