fix(pwa): harden startup recovery and track watchdog events

Adds a production boot watchdog to self-heal white/black-screen startup stalls without clearing IndexedDB data offline, reducing failure loops after frequent deploys. Also records watchdog recovery paths in Plausible and documents the new events/properties for monitoring stability.

Co-authored-by: Cursor <cursoragent@cursor.com>

client/src/main.tsx

@@ -7,6 +7,7 @@ import './App.css'
 import './i18n'
 import App from './App.tsx'
 import { applyAppearanceToDocument } from './services/appearance.ts'
+import { flushPendingPwaBootEvents } from './services/analytics.ts'
 import {
   installStaleAssetRecovery,
   markReloadAttempt,
@@ -14,6 +15,15 @@ import {
 } from './services/pwaStartup.ts'
 import { redirectToPasskeyCompatibleHostIfNeeded } from './utils/passkeyHost.ts'
 
+declare global {
+  interface Window {
+    __KDB_MAIN_MODULE_LOADED?: boolean
+    __KDB_APP_BOOTSTRAPPED?: boolean
+  }
+}
+
+window.__KDB_MAIN_MODULE_LOADED = true
+
 /** Stale PWA precache on localhost can shadow Vite dev modules. */
 async function clearDevServiceWorkerCaches(): Promise<void> {
   if (!import.meta.env.DEV || !('serviceWorker' in navigator)) return
@@ -47,6 +57,10 @@ async function bootstrap(): Promise<void> {
 
   applyAppearanceToDocument()
   installStaleAssetRecovery()
+  flushPendingPwaBootEvents()
+  window.addEventListener('load', () => {
+    flushPendingPwaBootEvents()
+  }, { once: true })
   await clearDevServiceWorkerCaches()
 
   const startupResult = await reconcileVersionOnStartup()
@@ -69,6 +83,7 @@ async function bootstrap(): Promise<void> {
       <App />
     </StrictMode>,
   )
+  window.__KDB_APP_BOOTSTRAPPED = true
 }
 
 void bootstrap().catch((err) => {
@@ -76,4 +91,5 @@ void bootstrap().catch((err) => {
   renderBootstrapError(
     'Die App konnte nicht gestartet werden. Bitte neu laden oder die App vollständig beenden und erneut öffnen.',
   )
+  window.__KDB_APP_BOOTSTRAPPED = true
 })

client/src/services/analytics.ts

@@ -41,7 +41,11 @@ export const PlausibleEvents = {
   LIVE_LOG_OPENED: 'Live Log Opened',
   LIVE_LOG_EVENT_LOGGED: 'Live Log Event Logged',
   LIVE_LOG_PHOTO_UPLOADED: 'Live Log Photo Uploaded',
-  OWM_WEATHER_FETCHED: 'OWM Weather Fetched'
+  OWM_WEATHER_FETCHED: 'OWM Weather Fetched',
+  PWA_BOOT_WATCHDOG_SOFT: 'PWA Boot Watchdog Soft',
+  PWA_BOOT_WATCHDOG_HARD: 'PWA Boot Watchdog Hard',
+  PWA_BOOT_WATCHDOG_FALLBACK: 'PWA Boot Watchdog Fallback',
+  PWA_BOOT_WATCHDOG_MANUAL_REPAIR: 'PWA Boot Watchdog Manual Repair'
 } as const
 
 /** Where a successful OpenWeatherMap API call originated (no coordinates or place names). */
@@ -50,6 +54,13 @@ export type OwmAnalyticsSource = 'live_log' | 'entry_editor' | 'entry_editor_gps
 export type PlausibleEventName = (typeof PlausibleEvents)[keyof typeof PlausibleEvents]
 
 export type PlausibleEventProps = Record<string, string | number | boolean>
+type PendingPwaBootEvent = {
+  name: PlausibleEventName
+  props?: PlausibleEventProps
+  ts?: number
+}
+
+const PWA_BOOT_PENDING_EVENTS_KEY = 'pwa_boot_pending_events'
 
 export function trackPlausibleEvent(name: PlausibleEventName, props?: PlausibleEventProps): void {
   if (typeof window.plausible !== 'function') return
@@ -59,3 +70,52 @@ export function trackPlausibleEvent(name: PlausibleEventName, props?: PlausibleE
   }
   window.plausible(name)
 }
+
+export function flushPendingPwaBootEvents(): number {
+  if (typeof window.plausible !== 'function') return 0
+
+  let raw: string | null = null
+  try {
+    raw = sessionStorage.getItem(PWA_BOOT_PENDING_EVENTS_KEY)
+  } catch {
+    return 0
+  }
+  if (!raw) return 0
+
+  let pending: PendingPwaBootEvent[]
+  try {
+    pending = JSON.parse(raw) as PendingPwaBootEvent[]
+  } catch {
+    try {
+      sessionStorage.removeItem(PWA_BOOT_PENDING_EVENTS_KEY)
+    } catch {
+      /* ignore storage errors */
+    }
+    return 0
+  }
+
+  if (!Array.isArray(pending) || pending.length === 0) {
+    try {
+      sessionStorage.removeItem(PWA_BOOT_PENDING_EVENTS_KEY)
+    } catch {
+      /* ignore storage errors */
+    }
+    return 0
+  }
+
+  for (const event of pending) {
+    if (!event || typeof event.name !== 'string') continue
+    if (event.props && Object.keys(event.props).length > 0) {
+      window.plausible(event.name, { props: event.props })
+    } else {
+      window.plausible(event.name)
+    }
+  }
+
+  try {
+    sessionStorage.removeItem(PWA_BOOT_PENDING_EVENTS_KEY)
+  } catch {
+    /* ignore storage errors */
+  }
+  return pending.length
+}