Fix beta preset selection and improve test plan builder UI

tests/unit/beta-evaluation.test.ts

@@ -6,6 +6,18 @@ const signal = (event: TestSignal['event'], extra: Partial<TestSignal> = {}): Te
 const planWith = (...kinds: Parameters<typeof requirement>[0][]): BetaPlan => ({ ...defaultPlan(), requirements: kinds.map((k, i) => requirement(k, `r${i}`)) });
 
 describe('beta requirement evaluation', () => {
+    it('copies a reactive preset without cloning proxies or mutating the saved requirements', () => {
+        const source = defaultPlan();
+        const proxied = new Proxy(source, { get(target, key, receiver) {
+            return key === 'requirements' ? new Proxy(target.requirements, {}) : Reflect.get(target, key, receiver);
+        } });
+        const selected = parseBetaPlan(proxied);
+        expect(selected).toEqual(source);
+        selected.requirements[0].target = 15;
+        selected.requirements.push(requirement('round', 'round'));
+        expect(source.requirements).toHaveLength(1);
+        expect(source.requirements[0].target).toBe(1);
+    });
     it('validates plans without accepting unknown kinds, duplicate IDs, fractional counts or unsafe numbers', () => {
         expect(parseBetaPlan(defaultPlan())).toEqual(defaultPlan());
         expect(() => parseBetaPlan({ ...defaultPlan(), requirements: [] })).toThrow();