diff --git a/src/store.js b/src/store.js
new file mode 100644
index 0000000..73ace45
--- /dev/null
+++ b/src/store.js
@@ -0,0 +1,78 @@
+import { parseTarget } from './pure.js';
+
+const KEY_TARGETS = 'tat.targets';
+const KEY_HISTORY = 'tat.history';
+const KEY_PREFS = 'tat.prefs';
+
+const DEFAULT_PREFS = { version: 1, mode: 'free', pos: { x: 0, y: 0 } };
+
+export class Store {
+  constructor({ storage, onWarn = (m) => console.warn(m) } = {}) {
+    if (!storage) throw new Error('Store requires a storage object');
+    this.storage = storage;
+    this.onWarn = onWarn;
+    this.targets = this._loadJson(KEY_TARGETS, {});
+    this.history = this._loadJson(KEY_HISTORY, {});
+    this.prefs = this._mergePrefs(this._loadJson(KEY_PREFS, null));
+  }
+
+  _loadJson(key, fallback) {
+    let raw;
+    try {
+      raw = this.storage.getItem(key);
+    } catch {
+      return fallback;
+    }
+    if (raw == null) return fallback;
+    try {
+      return JSON.parse(raw);
+    } catch {
+      this.onWarn(`[tat] discarding corrupted ${key}`);
+      try { this.storage.removeItem(key); } catch { /* noop */ }
+      return fallback;
+    }
+  }
+
+  _saveJson(key, value) {
+    try {
+      this.storage.setItem(key, JSON.stringify(value));
+      return true;
+    } catch (e) {
+      this.onWarn(`[tat] failed to persist ${key}: ${e.message}`);
+      return false;
+    }
+  }
+
+  _mergePrefs(loaded) {
+    if (!loaded || loaded.version !== 1) return { ...DEFAULT_PREFS };
+    return { ...DEFAULT_PREFS, ...loaded };
+  }
+
+  getTarget(attr) {
+    const v = this.targets[attr];
+    return typeof v === 'number' && v > 0 ? v : null;
+  }
+
+  setTarget(attr, value) {
+    const parsed = parseTarget(value);
+    if (parsed === null) return false;
+    this.targets[attr] = parsed;
+    return this._saveJson(KEY_TARGETS, this.targets);
+  }
+
+  getPrefs() {
+    return { ...this.prefs };
+  }
+
+  setMode(mode) {
+    if (mode !== 'free' && mode !== 'anchored') return false;
+    this.prefs.mode = mode;
+    return this._saveJson(KEY_PREFS, this.prefs);
+  }
+
+  setPos(pos) {
+    if (!pos || typeof pos.x !== 'number' || typeof pos.y !== 'number') return false;
+    this.prefs.pos = { x: pos.x, y: pos.y };
+    return this._saveJson(KEY_PREFS, this.prefs);
+  }
+}
diff --git a/tests/localstorage-shim.js b/tests/localstorage-shim.js
new file mode 100644
index 0000000..307fa26
--- /dev/null
+++ b/tests/localstorage-shim.js
@@ -0,0 +1,9 @@
+export function createLocalStorage() {
+  const data = new Map();
+  return {
+    getItem(k) { return data.has(k) ? data.get(k) : null; },
+    setItem(k, v) { data.set(k, String(v)); },
+    removeItem(k) { data.delete(k); },
+    clear() { data.clear(); },
+  };
+}
diff --git a/tests/store.test.js b/tests/store.test.js
new file mode 100644
index 0000000..286e2a9
--- /dev/null
+++ b/tests/store.test.js
@@ -0,0 +1,51 @@
+import { test } from 'node:test';
+import assert from 'node:assert/strict';
+import { Store } from '../src/store.js';
+import { createLocalStorage } from './localstorage-shim.js';
+
+function freshStore() {
+  return new Store({ storage: createLocalStorage() });
+}
+
+test('Store: starts empty', () => {
+  const s = freshStore();
+  assert.equal(s.getTarget('strength'), null);
+});
+
+test('Store: setTarget validates via parseTarget', () => {
+  const s = freshStore();
+  assert.equal(s.setTarget('strength', '25M'), true);
+  assert.equal(s.getTarget('strength'), 25_000_000);
+});
+
+test('Store: setTarget rejects invalid and keeps previous', () => {
+  const s = freshStore();
+  s.setTarget('strength', 25_000_000);
+  assert.equal(s.setTarget('strength', 'abc'), false);
+  assert.equal(s.getTarget('strength'), 25_000_000);
+});
+
+test('Store: targets are per-attribute', () => {
+  const s = freshStore();
+  s.setTarget('strength', 25_000_000);
+  s.setTarget('speed', 50_000_000);
+  assert.equal(s.getTarget('strength'), 25_000_000);
+  assert.equal(s.getTarget('speed'), 50_000_000);
+});
+
+test('Store: persists across instances via storage', () => {
+  const storage = createLocalStorage();
+  const a = new Store({ storage });
+  a.setTarget('strength', 25_000_000);
+  const b = new Store({ storage });
+  assert.equal(b.getTarget('strength'), 25_000_000);
+});
+
+test('Store: corrupted JSON is wiped with a warning', () => {
+  const storage = createLocalStorage();
+  storage.setItem('tat.targets', '{not json');
+  const warnings = [];
+  const s = new Store({ storage, onWarn: (m) => warnings.push(m) });
+  assert.equal(s.getTarget('strength'), null);
+  assert.equal(warnings.length, 1);
+});