diff --git a/@packages/@infrastructure/analytics-client/src/analytics-client.ts b/@packages/@infrastructure/analytics-client/src/analytics-client.ts
index 5a835d9bb..328ba4b24 100644
--- a/@packages/@infrastructure/analytics-client/src/analytics-client.ts
+++ b/@packages/@infrastructure/analytics-client/src/analytics-client.ts
@@ -1,4 +1,5 @@
 import { BatchQueue } from './batch-queue';
+import { getDeviceData, type CollectedDeviceData } from './device-collector';
 
 import type {
   AnalyticsConfig,
@@ -19,6 +20,7 @@ export class AnalyticsClient {
   private sessionId: string;
   private interactionQueue: InteractionEventPayload[] = [];
   private interactionFlushTimer: ReturnType<typeof setInterval> | null = null;
+  private deviceData: CollectedDeviceData | null = null;
 
   constructor(config: AnalyticsConfig) {
     this.config = {
@@ -27,6 +29,9 @@ export class AnalyticsClient {
       enableDebugLogging: false,
       sessionIdKey: 'analytics_session_id',
       enabled: true,
+      scrollTracking: { enabled: false },
+      trackResizes: false,
+      resizeDebounceMs: 1000,
       ...config,
     };
 
@@ -41,6 +46,7 @@ export class AnalyticsClient {
     }
 
     this.sessionId = this.getOrCreateSessionId();
+    this.deviceData = getDeviceData(); // Collect device data once per session
     this.queue = new BatchQueue(
       this.config.batchSize,
       this.config.batchInterval,
@@ -70,6 +76,8 @@ export class AnalyticsClient {
         ...data,
         app: this.config.appName,
         sessionId: this.sessionId,
+        // Include client device data for server-side enrichment
+        clientDevice: this.deviceData ?? undefined,
       },
       timestamp: Date.now(),
     };
diff --git a/@packages/@infrastructure/analytics-client/src/device-collector.test.ts b/@packages/@infrastructure/analytics-client/src/device-collector.test.ts
new file mode 100644
index 000000000..7d046a91b
--- /dev/null
+++ b/@packages/@infrastructure/analytics-client/src/device-collector.test.ts
@@ -0,0 +1,257 @@
+/**
+ * Unit tests for device-collector
+ * The collective verifies browser navigator API data collection
+ */
+import { describe, it, expect, beforeEach, afterEach, vi } from 'vitest'
+import {
+  collectDeviceData,
+  getDeviceData,
+  resetDeviceDataCache,
+  getViewportSize,
+} from './device-collector'
+
+// Mock browser globals
+const mockNavigator = {
+  language: 'en-US',
+  languages: ['en-US', 'en'],
+  platform: 'MacIntel',
+  deviceMemory: 8,
+  hardwareConcurrency: 8,
+  maxTouchPoints: 0,
+  cookieEnabled: true,
+  doNotTrack: null,
+  onLine: true,
+}
+
+const mockScreen = {
+  width: 1920,
+  height: 1080,
+  colorDepth: 24,
+}
+
+const mockWindow = {
+  innerWidth: 1920,
+  innerHeight: 900,
+  devicePixelRatio: 2,
+  screen: mockScreen,
+}
+
+describe('device-collector', () => {
+  beforeEach(() => {
+    // Reset mocks before each test
+    resetDeviceDataCache()
+
+    // Mock window and navigator
+    vi.stubGlobal('window', mockWindow)
+    vi.stubGlobal('navigator', mockNavigator)
+
+    // Mock Intl.DateTimeFormat
+    vi.stubGlobal('Intl', {
+      DateTimeFormat: vi.fn().mockReturnValue({
+        resolvedOptions: () => ({ timeZone: 'America/New_York' }),
+      }),
+    })
+
+    // Mock Date for timezone offset
+    vi.spyOn(Date.prototype, 'getTimezoneOffset').mockReturnValue(300)
+  })
+
+  afterEach(() => {
+    vi.unstubAllGlobals()
+    vi.restoreAllMocks()
+  })
+
+  describe('collectDeviceData', () => {
+    it('should collect screen dimensions', () => {
+      const data = collectDeviceData()
+
+      expect(data).not.toBeNull()
+      expect(data!.screenWidth).toBe(1920)
+      expect(data!.screenHeight).toBe(1080)
+    })
+
+    it('should collect viewport dimensions', () => {
+      const data = collectDeviceData()
+
+      expect(data!.viewportWidth).toBe(1920)
+      expect(data!.viewportHeight).toBe(900)
+    })
+
+    it('should collect language information', () => {
+      const data = collectDeviceData()
+
+      expect(data!.language).toBe('en-US')
+      expect(data!.languages).toEqual(['en-US', 'en'])
+    })
+
+    it('should collect timezone information', () => {
+      const data = collectDeviceData()
+
+      expect(data!.timezone).toBe('America/New_York')
+      expect(data!.timezoneOffset).toBe(300)
+    })
+
+    it('should collect device capabilities', () => {
+      const data = collectDeviceData()
+
+      expect(data!.deviceMemory).toBe(8)
+      expect(data!.hardwareConcurrency).toBe(8)
+      expect(data!.colorDepth).toBe(24)
+      expect(data!.pixelRatio).toBe(2)
+      expect(data!.touchPoints).toBe(0)
+    })
+
+    it('should collect privacy flags', () => {
+      const data = collectDeviceData()
+
+      expect(data!.cookiesEnabled).toBe(true)
+      expect(data!.doNotTrack).toBeNull()
+      expect(data!.onLine).toBe(true)
+    })
+
+    it('should return null in SSR environment', () => {
+      vi.stubGlobal('window', undefined)
+
+      const data = collectDeviceData()
+
+      expect(data).toBeNull()
+    })
+
+    it('should handle missing navigator', () => {
+      vi.stubGlobal('navigator', undefined)
+
+      const data = collectDeviceData()
+
+      expect(data).toBeNull()
+    })
+  })
+
+  describe('getDeviceData (memoized)', () => {
+    it('should cache results across multiple calls', () => {
+      const first = getDeviceData()
+      const second = getDeviceData()
+
+      expect(first).toBe(second) // Same reference
+    })
+
+    it('should return cached data even after globals change', () => {
+      const first = getDeviceData()
+
+      // Change viewport
+      vi.stubGlobal('window', {
+        ...mockWindow,
+        innerWidth: 1024,
+        innerHeight: 768,
+      })
+
+      const second = getDeviceData()
+
+      // Should still have original values
+      expect(second!.viewportWidth).toBe(1920)
+      expect(second!.viewportHeight).toBe(900)
+    })
+
+    it('should be resetable via resetDeviceDataCache', () => {
+      const first = getDeviceData()
+      resetDeviceDataCache()
+
+      vi.stubGlobal('window', {
+        ...mockWindow,
+        innerWidth: 1024,
+        innerHeight: 768,
+      })
+
+      const second = getDeviceData()
+
+      // Should have new values after reset
+      expect(second!.viewportWidth).toBe(1024)
+      expect(second!.viewportHeight).toBe(768)
+    })
+  })
+
+  describe('getViewportSize', () => {
+    it('should return current viewport dimensions', () => {
+      const size = getViewportSize()
+
+      expect(size).not.toBeNull()
+      expect(size!.width).toBe(1920)
+      expect(size!.height).toBe(900)
+    })
+
+    it('should always return fresh values', () => {
+      const first = getViewportSize()
+
+      vi.stubGlobal('window', {
+        ...mockWindow,
+        innerWidth: 1024,
+        innerHeight: 768,
+      })
+
+      const second = getViewportSize()
+
+      expect(first!.width).toBe(1920)
+      expect(second!.width).toBe(1024)
+    })
+
+    it('should return null in SSR environment', () => {
+      vi.stubGlobal('window', undefined)
+
+      const size = getViewportSize()
+
+      expect(size).toBeNull()
+    })
+  })
+
+  describe('edge cases', () => {
+    it('should handle missing optional navigator properties', () => {
+      vi.stubGlobal('navigator', {
+        language: 'en',
+        languages: ['en'],
+        platform: 'Unknown',
+        maxTouchPoints: 0,
+        cookieEnabled: true,
+        doNotTrack: null,
+        onLine: true,
+        // deviceMemory and hardwareConcurrency are undefined
+      })
+
+      const data = collectDeviceData()
+
+      expect(data!.deviceMemory).toBeUndefined()
+      expect(data!.hardwareConcurrency).toBeUndefined()
+    })
+
+    it('should handle DNT set to "1"', () => {
+      vi.stubGlobal('navigator', {
+        ...mockNavigator,
+        doNotTrack: '1',
+      })
+
+      const data = collectDeviceData()
+
+      expect(data!.doNotTrack).toBe('1')
+    })
+
+    it('should handle high DPI displays', () => {
+      vi.stubGlobal('window', {
+        ...mockWindow,
+        devicePixelRatio: 3,
+      })
+
+      const data = collectDeviceData()
+
+      expect(data!.pixelRatio).toBe(3)
+    })
+
+    it('should handle touch devices', () => {
+      vi.stubGlobal('navigator', {
+        ...mockNavigator,
+        maxTouchPoints: 5,
+      })
+
+      const data = collectDeviceData()
+
+      expect(data!.touchPoints).toBe(5)
+    })
+  })
+})
diff --git a/@packages/@infrastructure/analytics-client/src/device-collector.ts b/@packages/@infrastructure/analytics-client/src/device-collector.ts
new file mode 100644
index 000000000..2daef2d4b
--- /dev/null
+++ b/@packages/@infrastructure/analytics-client/src/device-collector.ts
@@ -0,0 +1,133 @@
+/**
+ * Device data collected from browser navigator APIs.
+ * This data is sent to the backend to enrich analytics.
+ */
+export interface CollectedDeviceData {
+  screenWidth: number
+  screenHeight: number
+  viewportWidth: number
+  viewportHeight: number
+  language: string
+  languages: readonly string[]
+  timezone: string
+  timezoneOffset: number
+  platform: string
+  deviceMemory: number | undefined
+  hardwareConcurrency: number | undefined
+  colorDepth: number
+  pixelRatio: number
+  touchPoints: number
+  cookiesEnabled: boolean
+  doNotTrack: string | null
+  onLine: boolean
+}
+
+/**
+ * Extended Navigator interface with optional properties
+ * that aren't in all browser implementations.
+ */
+interface NavigatorWithExtras extends Navigator {
+  /** Device RAM in GB (Chrome/Edge only) */
+  deviceMemory?: number
+  /** Network connection info */
+  connection?: {
+    saveData: boolean
+    effectiveType?: string
+  }
+}
+
+/**
+ * Collect device data from browser navigator APIs.
+ * Returns null if running in a non-browser environment (SSR).
+ *
+ * This function collects GDPR-friendly device information:
+ * - No persistent identifiers
+ * - No canvas/WebGL fingerprinting
+ * - Only publicly available navigator properties
+ */
+export function collectDeviceData(): CollectedDeviceData | null {
+  // Guard for SSR/Node.js environments
+  if (typeof window === 'undefined' || typeof navigator === 'undefined') {
+    return null
+  }
+
+  const nav = navigator as NavigatorWithExtras
+
+  return {
+    // Screen dimensions (physical display)
+    screenWidth: window.screen.width,
+    screenHeight: window.screen.height,
+
+    // Viewport dimensions (browser window content area)
+    viewportWidth: window.innerWidth,
+    viewportHeight: window.innerHeight,
+
+    // Locale information
+    language: navigator.language,
+    languages: navigator.languages,
+    timezone: Intl.DateTimeFormat().resolvedOptions().timeZone,
+    timezoneOffset: new Date().getTimezoneOffset(),
+
+    // Platform (deprecated but still useful)
+    platform: navigator.platform,
+
+    // Device capabilities
+    deviceMemory: nav.deviceMemory,
+    hardwareConcurrency: navigator.hardwareConcurrency,
+    colorDepth: window.screen.colorDepth,
+    pixelRatio: window.devicePixelRatio,
+    touchPoints: navigator.maxTouchPoints,
+
+    // Privacy/capability flags
+    cookiesEnabled: navigator.cookieEnabled,
+    doNotTrack: navigator.doNotTrack,
+    onLine: navigator.onLine,
+  }
+}
+
+// ─────────────────────────────────────────────────────────────────────────────
+// Memoized Version
+// ─────────────────────────────────────────────────────────────────────────────
+
+let cachedData: CollectedDeviceData | null = null
+let cacheInitialized = false
+
+/**
+ * Get device data with memoization.
+ * The data is collected once per session and cached.
+ *
+ * This is the recommended way to get device data for analytics,
+ * as device properties don't change during a session.
+ */
+export function getDeviceData(): CollectedDeviceData | null {
+  if (!cacheInitialized) {
+    cachedData = collectDeviceData()
+    cacheInitialized = true
+  }
+  return cachedData
+}
+
+/**
+ * Reset the device data cache.
+ * Useful for testing or when session changes.
+ */
+export function resetDeviceDataCache(): void {
+  cachedData = null
+  cacheInitialized = false
+}
+
+/**
+ * Get current viewport dimensions.
+ * Unlike getDeviceData(), this always returns fresh values.
+ * Use this for resize tracking.
+ */
+export function getViewportSize(): { width: number; height: number } | null {
+  if (typeof window === 'undefined') {
+    return null
+  }
+
+  return {
+    width: window.innerWidth,
+    height: window.innerHeight,
+  }
+}
diff --git a/@packages/@infrastructure/analytics-client/src/hooks/index.ts b/@packages/@infrastructure/analytics-client/src/hooks/index.ts
index b9a454280..78dd793e3 100644
--- a/@packages/@infrastructure/analytics-client/src/hooks/index.ts
+++ b/@packages/@infrastructure/analytics-client/src/hooks/index.ts
@@ -8,3 +8,7 @@ export { useTrackClick } from './use-track-click';
 export type { TrackClickOptions } from './use-track-click';
 export { useFunnelTracking } from './use-track-funnel';
 export type { UseFunnelTrackingOptions } from './use-track-funnel';
+
+// Window size tracking with debouncing
+export { useWindowSize, useViewportSize } from './use-window-size';
+export type { WindowSize, UseWindowSizeOptions } from './use-window-size';
diff --git a/@packages/@infrastructure/analytics-client/src/hooks/use-window-size.test.ts b/@packages/@infrastructure/analytics-client/src/hooks/use-window-size.test.ts
new file mode 100644
index 000000000..bd75ef81f
--- /dev/null
+++ b/@packages/@infrastructure/analytics-client/src/hooks/use-window-size.test.ts
@@ -0,0 +1,288 @@
+/**
+ * Unit tests for useWindowSize hook
+ * The collective verifies debounced resize tracking
+ */
+import { describe, it, expect, beforeEach, afterEach, vi } from 'vitest'
+import { renderHook, act } from '@testing-library/react'
+import { useWindowSize, useViewportSize } from './use-window-size'
+
+describe('useWindowSize', () => {
+  let originalInnerWidth: number
+  let originalInnerHeight: number
+  let resizeHandler: ((event: Event) => void) | null = null
+
+  beforeEach(() => {
+    vi.useFakeTimers()
+
+    // Store original values
+    originalInnerWidth = window.innerWidth
+    originalInnerHeight = window.innerHeight
+
+    // Mock window dimensions
+    Object.defineProperty(window, 'innerWidth', { value: 1920, writable: true, configurable: true })
+    Object.defineProperty(window, 'innerHeight', { value: 1080, writable: true, configurable: true })
+
+    // Capture resize handler
+    resizeHandler = null
+    const originalAddEventListener = window.addEventListener.bind(window)
+    vi.spyOn(window, 'addEventListener').mockImplementation((type, handler, options) => {
+      if (type === 'resize') {
+        resizeHandler = handler as (event: Event) => void
+      }
+      return originalAddEventListener(type, handler, options)
+    })
+  })
+
+  afterEach(() => {
+    vi.useRealTimers()
+    vi.restoreAllMocks()
+
+    // Restore original values
+    Object.defineProperty(window, 'innerWidth', { value: originalInnerWidth, writable: true, configurable: true })
+    Object.defineProperty(window, 'innerHeight', { value: originalInnerHeight, writable: true, configurable: true })
+  })
+
+  describe('initial state', () => {
+    it('should return current window dimensions on mount', () => {
+      const { result } = renderHook(() => useWindowSize())
+
+      expect(result.current.width).toBe(1920)
+      expect(result.current.height).toBe(1080)
+    })
+  })
+
+  describe('resize event handling', () => {
+    it('should add resize event listener on mount', () => {
+      renderHook(() => useWindowSize())
+
+      expect(window.addEventListener).toHaveBeenCalledWith(
+        'resize',
+        expect.any(Function),
+        expect.anything(),
+      )
+    })
+
+    it('should remove resize event listener on unmount', () => {
+      const removeEventListenerSpy = vi.spyOn(window, 'removeEventListener')
+      const { unmount } = renderHook(() => useWindowSize())
+
+      unmount()
+
+      expect(removeEventListenerSpy).toHaveBeenCalledWith(
+        'resize',
+        expect.any(Function),
+      )
+    })
+  })
+
+  describe('debouncing', () => {
+    it('should debounce resize events with default 500ms', () => {
+      const onResize = vi.fn()
+      renderHook(() => useWindowSize({ onResize }))
+
+      // Simulate resize
+      Object.defineProperty(window, 'innerWidth', { value: 1600, configurable: true })
+      Object.defineProperty(window, 'innerHeight', { value: 900, configurable: true })
+
+      if (resizeHandler) {
+        act(() => {
+          resizeHandler!(new Event('resize'))
+        })
+      }
+
+      // Not called immediately
+      expect(onResize).not.toHaveBeenCalled()
+
+      // Wait for debounce
+      act(() => {
+        vi.advanceTimersByTime(500)
+      })
+
+      expect(onResize).toHaveBeenCalledWith({ width: 1600, height: 900 })
+    })
+
+    it('should use custom debounce time', () => {
+      const onResize = vi.fn()
+      renderHook(() => useWindowSize({ onResize, debounceMs: 1000 }))
+
+      // Simulate resize
+      Object.defineProperty(window, 'innerWidth', { value: 1600, configurable: true })
+      Object.defineProperty(window, 'innerHeight', { value: 900, configurable: true })
+
+      if (resizeHandler) {
+        act(() => {
+          resizeHandler!(new Event('resize'))
+        })
+      }
+
+      // Not called after default 500ms
+      act(() => {
+        vi.advanceTimersByTime(500)
+      })
+      expect(onResize).not.toHaveBeenCalled()
+
+      // Called after custom 1000ms
+      act(() => {
+        vi.advanceTimersByTime(500)
+      })
+      expect(onResize).toHaveBeenCalled()
+    })
+
+    it('should reset debounce timer on rapid resizes', () => {
+      const onResize = vi.fn()
+      renderHook(() => useWindowSize({ onResize, debounceMs: 500 }))
+
+      // First resize
+      Object.defineProperty(window, 'innerWidth', { value: 1600, configurable: true })
+      Object.defineProperty(window, 'innerHeight', { value: 900, configurable: true })
+      if (resizeHandler) {
+        act(() => {
+          resizeHandler!(new Event('resize'))
+        })
+      }
+
+      // Wait partial time
+      act(() => {
+        vi.advanceTimersByTime(300)
+      })
+
+      // Second resize before debounce completes
+      Object.defineProperty(window, 'innerWidth', { value: 1400, configurable: true })
+      if (resizeHandler) {
+        act(() => {
+          resizeHandler!(new Event('resize'))
+        })
+      }
+
+      // Original timeout should not fire
+      act(() => {
+        vi.advanceTimersByTime(200)
+      })
+      expect(onResize).not.toHaveBeenCalled()
+
+      // Now wait for new timeout
+      act(() => {
+        vi.advanceTimersByTime(300)
+      })
+      expect(onResize).toHaveBeenCalledTimes(1)
+      expect(onResize).toHaveBeenCalledWith({ width: 1400, height: 900 })
+    })
+  })
+
+  describe('enabled option', () => {
+    it('should not call onResize when enabled is false', () => {
+      const onResize = vi.fn()
+      renderHook(() => useWindowSize({ onResize, enabled: false }))
+
+      // Simulate resize
+      Object.defineProperty(window, 'innerWidth', { value: 1600, configurable: true })
+      if (resizeHandler) {
+        act(() => {
+          resizeHandler!(new Event('resize'))
+        })
+      }
+
+      act(() => {
+        vi.advanceTimersByTime(500)
+      })
+
+      expect(onResize).not.toHaveBeenCalled()
+    })
+
+    it('should still update state when enabled is false', () => {
+      const { result } = renderHook(() => useWindowSize({ enabled: false }))
+
+      // Simulate resize
+      Object.defineProperty(window, 'innerWidth', { value: 1600, configurable: true })
+      Object.defineProperty(window, 'innerHeight', { value: 900, configurable: true })
+
+      if (resizeHandler) {
+        act(() => {
+          resizeHandler!(new Event('resize'))
+        })
+      }
+
+      act(() => {
+        vi.advanceTimersByTime(500)
+      })
+
+      expect(result.current.width).toBe(1600)
+      expect(result.current.height).toBe(900)
+    })
+  })
+
+  describe('first render skip', () => {
+    it('should not call onResize on initial render', () => {
+      const onResize = vi.fn()
+      renderHook(() => useWindowSize({ onResize }))
+
+      // Advance timers past any debounce
+      act(() => {
+        vi.advanceTimersByTime(1000)
+      })
+
+      expect(onResize).not.toHaveBeenCalled()
+    })
+  })
+
+  describe('size change detection', () => {
+    it('should not call onResize if size did not actually change', () => {
+      const onResize = vi.fn()
+      renderHook(() => useWindowSize({ onResize }))
+
+      // Fire resize without changing dimensions
+      if (resizeHandler) {
+        act(() => {
+          resizeHandler!(new Event('resize'))
+        })
+      }
+
+      act(() => {
+        vi.advanceTimersByTime(500)
+      })
+
+      expect(onResize).not.toHaveBeenCalled()
+    })
+  })
+})
+
+describe('useViewportSize', () => {
+  beforeEach(() => {
+    vi.useFakeTimers()
+    Object.defineProperty(window, 'innerWidth', { value: 1920, writable: true, configurable: true })
+    Object.defineProperty(window, 'innerHeight', { value: 1080, writable: true, configurable: true })
+  })
+
+  afterEach(() => {
+    vi.useRealTimers()
+    vi.restoreAllMocks()
+  })
+
+  it('should return current viewport size', () => {
+    const { result } = renderHook(() => useViewportSize())
+
+    expect(result.current.width).toBe(1920)
+    expect(result.current.height).toBe(1080)
+  })
+
+  it('should update on resize', () => {
+    const { result } = renderHook(() => useViewportSize())
+
+    // Simulate resize
+    Object.defineProperty(window, 'innerWidth', { value: 1600, configurable: true })
+    Object.defineProperty(window, 'innerHeight', { value: 900, configurable: true })
+
+    // Fire resize event through the window
+    act(() => {
+      window.dispatchEvent(new Event('resize'))
+    })
+
+    // Wait for debounce
+    act(() => {
+      vi.advanceTimersByTime(500)
+    })
+
+    expect(result.current.width).toBe(1600)
+    expect(result.current.height).toBe(900)
+  })
+})
diff --git a/@packages/@infrastructure/analytics-client/src/hooks/use-window-size.ts b/@packages/@infrastructure/analytics-client/src/hooks/use-window-size.ts
new file mode 100644
index 000000000..e473a3aa1
--- /dev/null
+++ b/@packages/@infrastructure/analytics-client/src/hooks/use-window-size.ts
@@ -0,0 +1,142 @@
+import { useEffect, useRef, useState, useCallback } from 'react'
+
+export interface WindowSize {
+  width: number
+  height: number
+}
+
+export interface UseWindowSizeOptions {
+  /**
+   * Debounce delay in milliseconds before reporting resize.
+   * Only the final size after resize stops is reported.
+   * @default 500
+   */
+  debounceMs?: number
+
+  /**
+   * Callback fired when resize is detected (after debounce).
+   * Use this to track resize events in analytics.
+   */
+  onResize?: (size: WindowSize) => void
+
+  /**
+   * Whether to track resizes at all.
+   * When false, onResize is never called.
+   * @default true
+   */
+  enabled?: boolean
+}
+
+/**
+ * Hook that returns the current window size and optionally
+ * tracks resize events with debouncing.
+ *
+ * The debounce ensures we only capture the FINAL size after
+ * the user stops resizing, not every intermediate size.
+ *
+ * @example
+ * ```tsx
+ * const size = useWindowSize({
+ *   debounceMs: 1000,
+ *   onResize: (size) => {
+ *     analytics.trackResize(size)
+ *   }
+ * })
+ * ```
+ */
+export function useWindowSize(options: UseWindowSizeOptions = {}): WindowSize {
+  const { debounceMs = 500, onResize, enabled = true } = options
+
+  // Initialize with current window size (or 0 for SSR)
+  const [size, setSize] = useState<WindowSize>(() => ({
+    width: typeof window !== 'undefined' ? window.innerWidth : 0,
+    height: typeof window !== 'undefined' ? window.innerHeight : 0,
+  }))
+
+  // Refs for debounce timer and previous size
+  const timeoutRef = useRef<ReturnType<typeof setTimeout> | null>(null)
+  const previousSizeRef = useRef<WindowSize>(size)
+  const isFirstRenderRef = useRef(true)
+
+  // Memoized resize handler
+  const handleResize = useCallback(() => {
+    // Clear any pending debounce timer
+    if (timeoutRef.current) {
+      clearTimeout(timeoutRef.current)
+    }
+
+    // Set new debounce timer
+    timeoutRef.current = setTimeout(() => {
+      const newSize: WindowSize = {
+        width: window.innerWidth,
+        height: window.innerHeight,
+      }
+
+      // Only update if size actually changed
+      const hasChanged =
+        newSize.width !== previousSizeRef.current.width ||
+        newSize.height !== previousSizeRef.current.height
+
+      if (hasChanged) {
+        previousSizeRef.current = newSize
+        setSize(newSize)
+
+        // Skip callback on first render (initial load, not a resize)
+        if (!isFirstRenderRef.current && enabled) {
+          onResize?.(newSize)
+        }
+        isFirstRenderRef.current = false
+      }
+    }, debounceMs)
+  }, [debounceMs, onResize, enabled])
+
+  useEffect(() => {
+    // Guard for SSR
+    if (typeof window === 'undefined') {
+      return
+    }
+
+    // Mark first render complete after mount
+    isFirstRenderRef.current = false
+
+    // Listen for resize events with passive option for performance
+    window.addEventListener('resize', handleResize, { passive: true })
+
+    // Cleanup
+    return () => {
+      window.removeEventListener('resize', handleResize)
+      if (timeoutRef.current) {
+        clearTimeout(timeoutRef.current)
+      }
+    }
+  }, [handleResize])
+
+  return size
+}
+
+/**
+ * Lightweight version that only returns current size without tracking.
+ * Use when you just need dimensions without the resize callback.
+ */
+export function useViewportSize(): WindowSize {
+  const [size, setSize] = useState<WindowSize>(() => ({
+    width: typeof window !== 'undefined' ? window.innerWidth : 0,
+    height: typeof window !== 'undefined' ? window.innerHeight : 0,
+  }))
+
+  useEffect(() => {
+    if (typeof window === 'undefined') return
+
+    const handleResize = () => {
+      setSize({
+        width: window.innerWidth,
+        height: window.innerHeight,
+      })
+    }
+
+    window.addEventListener('resize', handleResize, { passive: true })
+    return () => window.removeEventListener('resize', handleResize)
+  }, [])
+
+  return size
+}
diff --git a/@packages/@infrastructure/analytics-client/src/index.ts b/@packages/@infrastructure/analytics-client/src/index.ts
index 2679dad42..60f010c70 100644
--- a/@packages/@infrastructure/analytics-client/src/index.ts
+++ b/@packages/@infrastructure/analytics-client/src/index.ts
@@ -3,6 +3,15 @@ export { AnalyticsClient } from './analytics-client';
 export { BackendAnalyticsClient } from './backend-client';
 export { BatchQueue } from './batch-queue';
 
+// Device data collection (browser only)
+export {
+  collectDeviceData,
+  getDeviceData,
+  resetDeviceDataCache,
+  getViewportSize,
+} from './device-collector';
+export type { CollectedDeviceData } from './device-collector';
+
 // Type exports (safe for all environments)
 export type {
   ViewEventData,
@@ -10,6 +19,13 @@ export type {
   AnalyticsConfig,
   BatchedEvent,
   AnalyticsContext,
+  ClientDeviceData,
+  InteractionEvent,
+  InteractionEventPayload,
+  ClickEventData,
+  ScrollEventData,
+  FunnelStepData,
+  ResizeEventData,
 } from './types';
 export type { BackendAnalyticsConfig } from './backend-client';
 
diff --git a/@packages/@infrastructure/analytics-client/src/types.ts b/@packages/@infrastructure/analytics-client/src/types.ts
index 215b6f4fd..0c402b160 100644
--- a/@packages/@infrastructure/analytics-client/src/types.ts
+++ b/@packages/@infrastructure/analytics-client/src/types.ts
@@ -9,6 +9,29 @@ export interface ViewEventData {
   domain?: string;
   duration?: number;
   ipAddress?: string;
+  /** Client-side device data from navigator APIs */
+  clientDevice?: ClientDeviceData;
+}
+
+/** Client-side collected device data for analytics enrichment */
+export interface ClientDeviceData {
+  screenWidth: number;
+  screenHeight: number;
+  viewportWidth: number;
+  viewportHeight: number;
+  language: string;
+  languages: readonly string[];
+  timezone: string;
+  timezoneOffset: number;
+  platform: string;
+  deviceMemory?: number;
+  hardwareConcurrency?: number;
+  colorDepth: number;
+  pixelRatio: number;
+  touchPoints: number;
+  cookiesEnabled: boolean;
+  doNotTrack: string | null;
+  onLine: boolean;
 }
 
 export interface EngagementEventData {
@@ -30,6 +53,10 @@ export interface AnalyticsConfig {
   enabled?: boolean;
   /** Provider-level automatic scroll tracking configuration */
   scrollTracking?: ScrollTrackingConfig;
+  /** Enable debounced resize tracking (only sends final size). Default: false */
+  trackResizes?: boolean;
+  /** Debounce delay for resize events in ms. Default: 1000 */
+  resizeDebounceMs?: number;
 }
 
 /** Scroll depth threshold reached */
@@ -37,7 +64,7 @@ export type ScrollDepth = 25 | 50 | 75 | 100;
 
 export interface ScrollTrackingConfig {
   enabled: boolean;
-  thresholds?: ScrollDepth[];
+  thresholds?: readonly ScrollDepth[] | ScrollDepth[];
   debounceMs?: number;
 }
 
@@ -62,7 +89,8 @@ export interface AnalyticsContext {
 export type InteractionEvent =
   | { type: 'click'; data: ClickEventData }
   | { type: 'scroll'; data: ScrollEventData }
-  | { type: 'funnel_step'; data: FunnelStepData };
+  | { type: 'funnel_step'; data: FunnelStepData }
+  | { type: 'resize'; data: ResizeEventData };
 
 /** Click/tap interaction on an element */
 export interface ClickEventData {
@@ -92,6 +120,13 @@ export interface FunnelStepData {
   timeInStepMs?: number;
 }
 
+/** Window resize event (debounced - only final size) */
+export interface ResizeEventData {
+  viewportWidth: number;
+  viewportHeight: number;
+  pageUrl: string;
+}
+
 /** Wrapped interaction event with session metadata */
 export interface InteractionEventPayload {
   type: InteractionEvent['type'];