refactor(pwa): auf Workbox-Standard vereinfacht, refreshing-Flag

Der Zombie-Version-Check (858d4c1) ging über das Standard-Handshake-
Pattern hinaus. User will Industry-Standard: Workbox/web.dev-Pattern
ohne GET_VERSION-Sonderlocke.

Änderungen:
- service-worker.ts: GET_VERSION-Handler entfernt. SW reagiert nur
  noch auf SKIP_WAITING.
- pwa.svelte.ts: queryVersion + evaluateWaiting entfernt. init()
  zeigt Toast wieder schlicht bei registration.waiting (das ist
  kanonisch — bit-gleiche Bytes erzeugen keinen waiting-Slot).
- controllerchange-Listener wandert nach init() mit refreshing-Flag
  (CRA-Idiom): verhindert Doppel-Reload, wenn User zusätzlich F5
  drückt, und stellt sicher, dass der Listener in _jeder_ Session
  aktiv ist, nicht erst nach dem ersten reload()-Call.
- pwa-store.test.ts: Tests decken jetzt waiting→Toast, no-waiting→
  kein Toast, Handshake, refreshing-Flag und Sofort-Reload ab.

Der Zombie-Edge-Case (Browser-Quirk mit bit-identischem waiting-SW)
wird sich nach einmaligem Klick auflösen — erwarteter Trade-off
gegenüber der eingesparten Komplexität.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

tests/unit/pwa-store.test.ts

@@ -4,17 +4,7 @@ import { describe, it, expect, beforeEach, vi } from 'vitest';
 class FakeSW extends EventTarget {
   scriptURL = '/service-worker.js';
   state: 'installed' | 'activated' = 'activated';
-  version: string | null;
-  postMessage = vi.fn((msg: unknown, transfer?: Transferable[]) => {
-    if ((msg as { type?: string } | null)?.type === 'GET_VERSION') {
-      const port = transfer?.[0] as MessagePort | undefined;
-      if (port && this.version !== null) port.postMessage({ version: this.version });
-    }
-  });
-  constructor(version: string | null) {
-    super();
-    this.version = version;
-  }
+  postMessage = vi.fn();
 }
 
 type Reg = {
@@ -25,7 +15,10 @@ type Reg = {
   update: ReturnType<typeof vi.fn>;
 };
 
-function mountFakeSW(init: Partial<Reg>): Reg {
+function mountFakeSW(init: Partial<Reg>): {
+  registration: Reg;
+  container: { swListeners: Record<string, ((e: Event) => void)[]> };
+} {
   const registration: Reg = {
     active: init.active ?? null,
     waiting: init.waiting ?? null,
@@ -33,18 +26,21 @@ function mountFakeSW(init: Partial<Reg>): Reg {
     addEventListener: vi.fn(),
     update: vi.fn().mockResolvedValue(undefined)
   };
+  const swListeners: Record<string, ((e: Event) => void)[]> = {};
   Object.defineProperty(navigator, 'serviceWorker', {
     configurable: true,
     value: {
       ready: Promise.resolve(registration),
       controller: registration.active,
-      addEventListener: vi.fn()
+      addEventListener: vi.fn((type: string, fn: (e: Event) => void) => {
+        (swListeners[type] ??= []).push(fn);
+      })
     }
   });
-  return registration;
+  return { registration, container: { swListeners } };
 }
 
-async function flush(ms = 20): Promise<void> {
+async function flush(ms = 10): Promise<void> {
   await new Promise((r) => setTimeout(r, ms));
 }
 
@@ -53,9 +49,9 @@ describe('pwa store', () => {
     vi.resetModules();
   });
 
-  it('bleibt still, wenn waiting- und active-SW dieselbe Version melden (Zombie)', async () => {
-    const active = new FakeSW('1776526292782');
-    const waiting = new FakeSW('1776526292782');
+  it('zeigt Toast, wenn beim Mount ein waiting-SW existiert', async () => {
+    const active = new FakeSW();
+    const waiting = new FakeSW();
     waiting.state = 'installed';
     mountFakeSW({ active, waiting });
 
@@ -63,43 +59,25 @@ describe('pwa store', () => {
     await pwaStore.init();
     await flush();
 
+    expect(pwaStore.updateAvailable).toBe(true);
+  });
+
+  it('zeigt keinen Toast ohne waiting-SW', async () => {
+    const active = new FakeSW();
+    mountFakeSW({ active });
+
+    const { pwaStore } = await import('../../src/lib/client/pwa.svelte');
+    await pwaStore.init();
+    await flush();
+
     expect(pwaStore.updateAvailable).toBe(false);
-    expect(waiting.postMessage).toHaveBeenCalledWith({ type: 'SKIP_WAITING' });
   });
 
-  it('zeigt Toast, wenn sich die Versionen unterscheiden', async () => {
-    const active = new FakeSW('1776526292782');
-    const waiting = new FakeSW('1776999999999');
+  it('reload() postet SKIP_WAITING und reloadet erst beim controllerchange', async () => {
+    const active = new FakeSW();
+    const waiting = new FakeSW();
     waiting.state = 'installed';
-    mountFakeSW({ active, waiting });
-
-    const { pwaStore } = await import('../../src/lib/client/pwa.svelte');
-    await pwaStore.init();
-    await flush();
-
-    expect(pwaStore.updateAvailable).toBe(true);
-    expect(waiting.postMessage).not.toHaveBeenCalledWith({ type: 'SKIP_WAITING' });
-  });
-
-  it('zeigt Toast, wenn der alte active-SW keine Version liefert (Fallback)', async () => {
-    const active = new FakeSW(null);
-    const waiting = new FakeSW('1776999999999');
-    waiting.state = 'installed';
-    mountFakeSW({ active, waiting });
-
-    const { pwaStore } = await import('../../src/lib/client/pwa.svelte');
-    await pwaStore.init();
-    await flush();
-
-    expect(pwaStore.updateAvailable).toBe(true);
-  });
-
-  it('reload() ohne waiting-SW macht nur location.reload()', async () => {
-    const active = new FakeSW('1776526292782');
-    mountFakeSW({ active });
-    const { pwaStore } = await import('../../src/lib/client/pwa.svelte');
-    await pwaStore.init();
-    await flush();
+    const { container } = mountFakeSW({ active, waiting });
 
     const reload = vi.fn();
     Object.defineProperty(window, 'location', {
@@ -107,7 +85,60 @@ describe('pwa store', () => {
       value: { ...window.location, reload }
     });
 
+    const { pwaStore } = await import('../../src/lib/client/pwa.svelte');
+    await pwaStore.init();
+    await flush();
+
     pwaStore.reload();
-    expect(reload).toHaveBeenCalled();
+    expect(waiting.postMessage).toHaveBeenCalledWith({ type: 'SKIP_WAITING' });
+    expect(reload).not.toHaveBeenCalled();
+
+    // Simuliere controllerchange, wenn der neue SW übernimmt.
+    container.swListeners['controllerchange']?.forEach((fn) => fn(new Event('controllerchange')));
+    expect(reload).toHaveBeenCalledTimes(1);
+  });
+
+  it('refreshing-Flag verhindert doppelten Reload bei mehrfachem controllerchange', async () => {
+    const active = new FakeSW();
+    const waiting = new FakeSW();
+    waiting.state = 'installed';
+    const { container } = mountFakeSW({ active, waiting });
+
+    const reload = vi.fn();
+    Object.defineProperty(window, 'location', {
+      configurable: true,
+      value: { ...window.location, reload }
+    });
+
+    const { pwaStore } = await import('../../src/lib/client/pwa.svelte');
+    await pwaStore.init();
+    await flush();
+
+    const fire = () =>
+      container.swListeners['controllerchange']?.forEach((fn) =>
+        fn(new Event('controllerchange'))
+      );
+    pwaStore.reload();
+    fire();
+    fire();
+    expect(reload).toHaveBeenCalledTimes(1);
+  });
+
+  it('reload() ohne waiting-SW löst location.reload() sofort aus', async () => {
+    const active = new FakeSW();
+    mountFakeSW({ active });
+
+    const reload = vi.fn();
+    Object.defineProperty(window, 'location', {
+      configurable: true,
+      value: { ...window.location, reload }
+    });
+
+    const { pwaStore } = await import('../../src/lib/client/pwa.svelte');
+    await pwaStore.init();
+    await flush();
+
+    pwaStore.reload();
+    expect(reload).toHaveBeenCalledTimes(1);
   });
 });