diff --git a/web/src/app/providers.tsx b/web/src/app/providers.tsx
index 24cd699..e99b21e 100644
--- a/web/src/app/providers.tsx
+++ b/web/src/app/providers.tsx
@@ -1,8 +1,14 @@
 'use client';
 
+import { useEffect } from 'react';
 import { AuthProvider } from '@/lib/auth-context';
+import { initTelemetry } from '@/lib/telemetry';
 import type { ReactNode } from 'react';
 
 export function Providers({ children }: { children: ReactNode }) {
+  useEffect(() => {
+    initTelemetry();
+  }, []);
+
   return <AuthProvider>{children}</AuthProvider>;
 }
diff --git a/web/src/lib/telemetry.ts b/web/src/lib/telemetry.ts
new file mode 100644
index 0000000..0302b4f
--- /dev/null
+++ b/web/src/lib/telemetry.ts
@@ -0,0 +1,155 @@
+// ── Platform Telemetry Client ─────────────────────────────────
+// Sends lightweight events to platform-service telemetry endpoint.
+// Runs in the browser only. Privacy: no PII, only action names + timing.
+
+import { PRODUCT_ID } from './platform-sync';
+
+const PLATFORM = 'web';
+const OS_FAMILY = 'other';
+const CHANNEL = 'pwa';
+const MAX_QUEUE = 50;
+const FLUSH_INTERVAL_MS = 30_000;
+
+interface TelemetryEvent {
+  id: string;
+  productId: string;
+  anonymousInstallId: string;
+  sessionId: string;
+  platform: string;
+  channel: string;
+  osFamily: string;
+  osVersion: string;
+  appVersion: string;
+  buildNumber: string;
+  releaseChannel: string;
+  eventType: string;
+  module: string;
+  eventName: string;
+  feature?: string;
+  message?: string;
+  tags?: Record<string, string>;
+  metrics?: Record<string, number>;
+  occurredAt: string;
+}
+
+let queue: TelemetryEvent[] = [];
+let sessionId = '';
+let installId = '';
+let flushTimer: ReturnType<typeof setInterval> | null = null;
+let baseUrl = '';
+
+function uuid(): string {
+  if (typeof crypto?.randomUUID === 'function') return crypto.randomUUID();
+  return 'xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx'.replace(/[xy]/g, (c) => {
+    const r = (Math.random() * 16) | 0;
+    return (c === 'x' ? r : (r & 0x3) | 0x8).toString(16);
+  });
+}
+
+function getInstallId(): string {
+  if (installId) return installId;
+  try {
+    const stored = localStorage.getItem('chronomind_telemetry_install_id');
+    if (stored) {
+      installId = stored;
+      return installId;
+    }
+    installId = uuid();
+    localStorage.setItem('chronomind_telemetry_install_id', installId);
+  } catch {
+    installId = uuid();
+  }
+  return installId;
+}
+
+export function trackEvent(
+  eventType: 'debug' | 'info' | 'warn' | 'error',
+  module: string,
+  eventName: string,
+  options?: {
+    feature?: string;
+    message?: string;
+    tags?: Record<string, string>;
+    metrics?: Record<string, number>;
+  }
+): void {
+  if (typeof window === 'undefined') return;
+
+  const event: TelemetryEvent = {
+    id: uuid(),
+    productId: PRODUCT_ID,
+    anonymousInstallId: getInstallId(),
+    sessionId,
+    platform: PLATFORM,
+    channel: CHANNEL,
+    osFamily: OS_FAMILY,
+    osVersion: navigator.userAgent.substring(0, 128),
+    appVersion: '0.1.0',
+    buildNumber: '1',
+    releaseChannel: 'beta',
+    eventType,
+    module,
+    eventName,
+    occurredAt: new Date().toISOString(),
+    ...options,
+  };
+
+  queue.push(event);
+  if (queue.length > MAX_QUEUE) {
+    queue = queue.slice(-MAX_QUEUE);
+  }
+
+  if (queue.length >= 10) {
+    flush();
+  }
+}
+
+export function trackTimerEvent(eventName: string, tags?: Record<string, string>, metrics?: Record<string, number>): void {
+  trackEvent('info', 'timers', eventName, { tags, metrics });
+}
+
+export function trackPageView(path: string): void {
+  trackEvent('info', 'navigation', 'page_view', { tags: { path } });
+}
+
+export function flush(): void {
+  if (typeof window === 'undefined' || queue.length === 0 || !baseUrl) return;
+
+  const events = [...queue];
+  queue = [];
+
+  const body = JSON.stringify({ productId: PRODUCT_ID, events });
+  const url = `${baseUrl}/telemetry/events`;
+
+  try {
+    const sent = navigator.sendBeacon(url, body);
+    if (!sent) {
+      fetch(url, {
+        method: 'POST',
+        headers: { 'Content-Type': 'application/json' },
+        body,
+        keepalive: true,
+      }).catch(() => {});
+    }
+  } catch {
+    // Best effort — telemetry is non-critical
+  }
+}
+
+export function initTelemetry(): void {
+  if (typeof window === 'undefined') return;
+
+  baseUrl = process.env.NEXT_PUBLIC_PLATFORM_SERVICE_URL ?? 'https://api.chronomind.app';
+  sessionId = uuid();
+
+  window.addEventListener('visibilitychange', () => {
+    if (document.visibilityState === 'hidden') {
+      flush();
+    }
+  });
+
+  if (flushTimer) clearInterval(flushTimer);
+  flushTimer = setInterval(flush, FLUSH_INTERVAL_MS);
+
+  trackEvent('info', 'app_lifecycle', 'session_started');
+}