diff --git a/docs/en/references/data/cache-overview.md b/docs/en/references/data/cache-overview.md
index 6e28e061fb..87ab7d66cd 100644
--- a/docs/en/references/data/cache-overview.md
+++ b/docs/en/references/data/cache-overview.md
@@ -23,8 +23,9 @@ CacheService handles data that:
 - Best for: expensive computations, API response caching
 
 ### Shared Cache
-- Synchronized across all windows via IPC
-- Main process acts as the source of truth
+- Synchronized bidirectionally between Main and all Renderer windows via IPC
+- Main process maintains authoritative copy and provides initialization sync for new windows
+- New windows fetch complete shared cache state from Main on startup
 - Best for: window layouts, shared UI state
 
 ### Persist Cache
@@ -101,14 +102,17 @@ cacheService.set('temp.calculation', result, 30000)
 ## Main vs Renderer Responsibilities
 
 ### Main Process CacheService
-- Manages shared and persist cache storage
-- Handles IPC requests from renderers
-- Broadcasts updates to all windows
-- Manages TTL expiration for shared caches
+- Manages internal cache for Main process services
+- Maintains authoritative SharedCache with type-safe access (`getShared`, `setShared`, `hasShared`, `deleteShared`)
+- Provides `getAllShared()` for new window initialization sync
+- Handles IPC requests from renderers and broadcasts updates to all windows
+- Manages TTL expiration using absolute timestamps (`expireAt`) for precise cross-window sync
 
 ### Renderer Process CacheService
-- Manages local memory cache
-- Proxies shared/persist operations to Main
+- Manages local memory cache and SharedCache local copy
+- Syncs SharedCache from Main on window initialization (async, non-blocking)
+- Provides ready state tracking via `isSharedCacheReady()` and `onSharedCacheReady()`
+- Broadcasts cache updates to Main for cross-window sync
 - Handles hook subscriptions and updates
 - Local TTL management for memory cache
 
diff --git a/docs/en/references/data/cache-usage.md b/docs/en/references/data/cache-usage.md
index 2dfd0f8453..6e1c761362 100644
--- a/docs/en/references/data/cache-usage.md
+++ b/docs/en/references/data/cache-usage.md
@@ -106,6 +106,39 @@ const files = cacheService.getPersist('app.recent_files')
 cacheService.deletePersist('app.recent_files')
 ```
 
+## Main Process Usage
+
+Main process CacheService provides SharedCache for cross-window state management.
+
+### SharedCache in Main Process
+
+```typescript
+import { cacheService } from '@main/data/CacheService'
+
+// Type-safe (schema key) - matches Renderer's type system
+cacheService.setShared('window.layout', layoutConfig)
+const layout = cacheService.getShared('window.layout')
+
+// With TTL (30 seconds)
+cacheService.setShared('temp.state', state, 30000)
+
+// Check existence
+if (cacheService.hasShared('window.layout')) {
+  // ...
+}
+
+// Delete
+cacheService.deleteShared('window.layout')
+```
+
+**Note**: Main CacheService does NOT support Casual methods (`getSharedCasual`, etc.). Only schema-based type-safe access is available in Main process.
+
+### Sync Strategy
+
+- **Renderer → Main**: When Renderer calls `setShared()`, it broadcasts to Main via IPC. Main updates its SharedCache and relays to other windows.
+- **Main → Renderer**: When Main calls `setShared()`, it broadcasts to all Renderer windows.
+- **New Window Initialization**: New windows fetch complete SharedCache state from Main via `getAllShared()`. Uses Main-priority override strategy for conflicts.
+
 ## Type-Safe vs Casual Methods
 
 ### Type-Safe Methods
@@ -237,6 +270,34 @@ export interface MyDataType {
 const [data, setData] = useCache('myFeature.data', defaultValue)
 ```
 
+## Shared Cache Ready State
+
+Renderer CacheService provides ready state tracking for SharedCache initialization sync.
+
+```typescript
+import { cacheService } from '@data/CacheService'
+
+// Check if shared cache is ready
+if (cacheService.isSharedCacheReady()) {
+  // SharedCache has been synced from Main
+}
+
+// Register callback when ready
+const unsubscribe = cacheService.onSharedCacheReady(() => {
+  // Called immediately if already ready, or when sync completes
+  console.log('SharedCache ready!')
+})
+
+// Cleanup
+unsubscribe()
+```
+
+**Behavior notes**:
+- `getShared()` returns `undefined` before ready (expected behavior)
+- `setShared()` works immediately and broadcasts to Main (Main updates its cache)
+- Hooks like `useSharedCache` work normally - they set initial values and update when sync completes
+- Main-priority override: when sync completes, Main's values override local values
+
 ## Best Practices
 
 1. **Choose the right tier**: Memory for temp, Shared for cross-window, Persist for survival
@@ -244,3 +305,4 @@ const [data, setData] = useCache('myFeature.data', defaultValue)
 3. **Prefer type-safe keys**: Add to schema when possible
 4. **Clean up dynamic keys**: Remove casual cache entries when no longer needed
 5. **Consider data size**: Persist cache uses localStorage (limited to ~5MB)
+6. **Use absolute timestamps for sync**: CacheSyncMessage uses `expireAt` (absolute Unix timestamp) for precise cross-window TTL sync
diff --git a/packages/shared/IpcChannel.ts b/packages/shared/IpcChannel.ts
index c6611f19a4..c6db564802 100644
--- a/packages/shared/IpcChannel.ts
+++ b/packages/shared/IpcChannel.ts
@@ -343,6 +343,7 @@ export enum IpcChannel {
   // Data: Cache
   Cache_Sync = 'cache:sync',
   Cache_SyncBatch = 'cache:sync-batch',
+  Cache_GetAllShared = 'cache:get-all-shared',
 
   // Data: API Channels
   DataApi_Request = 'data-api:request',
diff --git a/packages/shared/data/cache/cacheSchemas.ts b/packages/shared/data/cache/cacheSchemas.ts
index 0c467d7682..16a68f2a92 100644
--- a/packages/shared/data/cache/cacheSchemas.ts
+++ b/packages/shared/data/cache/cacheSchemas.ts
@@ -101,11 +101,11 @@ export const DefaultUseCache: UseCacheSchema = {
 /**
  * Use shared cache schema for renderer hook
  */
-export type UseSharedCacheSchema = {
+export type SharedCacheSchema = {
   'example_scope.example_key': string
 }
 
-export const DefaultUseSharedCache: UseSharedCacheSchema = {
+export const DefaultSharedCache: SharedCacheSchema = {
   'example_scope.example_key': 'example default value'
 }
 
@@ -126,4 +126,4 @@ export const DefaultRendererPersistCache: RendererPersistCacheSchema = {
  */
 export type RendererPersistCacheKey = keyof RendererPersistCacheSchema
 export type UseCacheKey = keyof UseCacheSchema
-export type UseSharedCacheKey = keyof UseSharedCacheSchema
+export type SharedCacheKey = keyof SharedCacheSchema
diff --git a/packages/shared/data/cache/cacheTypes.ts b/packages/shared/data/cache/cacheTypes.ts
index 1ae71919bc..e39dd2877c 100644
--- a/packages/shared/data/cache/cacheTypes.ts
+++ b/packages/shared/data/cache/cacheTypes.ts
@@ -22,7 +22,7 @@ export interface CacheSyncMessage {
   type: 'shared' | 'persist'
   key: string
   value: any
-  ttl?: number
+  expireAt?: number // Absolute Unix timestamp for precise cross-window sync
 }
 
 /**
@@ -33,7 +33,7 @@ export interface CacheSyncBatchMessage {
   entries: Array<{
     key: string
     value: any
-    ttl?: number
+    expireAt?: number // Absolute Unix timestamp for precise cross-window sync
   }>
 }
 
diff --git a/src/main/data/CacheService.ts b/src/main/data/CacheService.ts
index 79e8104999..2d260e14d2 100644
--- a/src/main/data/CacheService.ts
+++ b/src/main/data/CacheService.ts
@@ -18,6 +18,7 @@
  */
 
 import { loggerService } from '@logger'
+import type { SharedCacheKey, SharedCacheSchema } from '@shared/data/cache/cacheSchemas'
 import type { CacheEntry, CacheSyncMessage } from '@shared/data/cache/cacheTypes'
 import { IpcChannel } from '@shared/IpcChannel'
 import { BrowserWindow, ipcMain } from 'electron'
@@ -42,9 +43,12 @@ export class CacheService {
   private static instance: CacheService
   private initialized = false
 
-  // Main process cache
+  // Main process internal cache
   private cache = new Map<string, CacheEntry>()
 
+  // Shared cache (synchronized with renderer windows)
+  private sharedCache = new Map<string, CacheEntry>()
+
   // GC timer reference and interval time (e.g., every 10 minutes)
   private gcInterval: NodeJS.Timeout | null = null
   private readonly GC_INTERVAL_MS = 10 * 60 * 1000
@@ -79,7 +83,7 @@ export class CacheService {
   // ============ Main Process Cache (Internal) ============
 
   /**
-   * Garbage collection logic
+   * Garbage collection logic for both internal and shared cache
    */
   private startGarbageCollection() {
     if (this.gcInterval) return
@@ -88,6 +92,7 @@ export class CacheService {
       const now = Date.now()
       let removedCount = 0
 
+      // Clean internal cache
       for (const [key, entry] of this.cache.entries()) {
         if (entry.expireAt && now > entry.expireAt) {
           this.cache.delete(key)
@@ -95,6 +100,14 @@ export class CacheService {
         }
       }
 
+      // Clean shared cache
+      for (const [key, entry] of this.sharedCache.entries()) {
+        if (entry.expireAt && now > entry.expireAt) {
+          this.sharedCache.delete(key)
+          removedCount++
+        }
+      }
+
       if (removedCount > 0) {
         logger.debug(`Garbage collection removed ${removedCount} expired items`)
       }
@@ -155,6 +168,110 @@ export class CacheService {
     return this.cache.delete(key)
   }
 
+  // ============ Shared Cache (Cross-window via IPC) ============
+
+  /**
+   * Get value from shared cache with TTL validation (type-safe)
+   * @param key - Schema-defined shared cache key
+   * @returns Cached value or undefined if not found or expired
+   */
+  getShared<K extends SharedCacheKey>(key: K): SharedCacheSchema[K] | undefined {
+    const entry = this.sharedCache.get(key)
+    if (!entry) return undefined
+
+    // Check TTL (lazy cleanup)
+    if (entry.expireAt && Date.now() > entry.expireAt) {
+      this.sharedCache.delete(key)
+      return undefined
+    }
+
+    return entry.value as SharedCacheSchema[K]
+  }
+
+  /**
+   * Set value in shared cache with cross-window broadcast (type-safe)
+   * @param key - Schema-defined shared cache key
+   * @param value - Value to cache (type inferred from schema)
+   * @param ttl - Time to live in milliseconds (optional)
+   */
+  setShared<K extends SharedCacheKey>(key: K, value: SharedCacheSchema[K], ttl?: number): void {
+    const expireAt = ttl ? Date.now() + ttl : undefined
+    const entry: CacheEntry = { value, expireAt }
+
+    this.sharedCache.set(key, entry)
+
+    // Broadcast to all renderer windows
+    this.broadcastSync({
+      type: 'shared',
+      key,
+      value,
+      expireAt
+    })
+
+    logger.verbose(`Set shared cache key "${key}"`)
+  }
+
+  /**
+   * Check if key exists in shared cache and is not expired (type-safe)
+   * @param key - Schema-defined shared cache key
+   * @returns True if key exists and is valid, false otherwise
+   */
+  hasShared<K extends SharedCacheKey>(key: K): boolean {
+    const entry = this.sharedCache.get(key)
+    if (!entry) return false
+
+    // Check TTL
+    if (entry.expireAt && Date.now() > entry.expireAt) {
+      this.sharedCache.delete(key)
+      return false
+    }
+
+    return true
+  }
+
+  /**
+   * Delete from shared cache with cross-window broadcast (type-safe)
+   * @param key - Schema-defined shared cache key
+   * @returns True if deletion succeeded
+   */
+  deleteShared<K extends SharedCacheKey>(key: K): boolean {
+    if (!this.sharedCache.has(key)) {
+      return true
+    }
+
+    this.sharedCache.delete(key)
+
+    // Broadcast deletion to all renderer windows
+    this.broadcastSync({
+      type: 'shared',
+      key,
+      value: undefined // undefined means deletion
+    })
+
+    logger.verbose(`Deleted shared cache key "${key}"`)
+    return true
+  }
+
+  /**
+   * Get all shared cache entries (for renderer initialization sync)
+   * @returns Record of all shared cache entries with their metadata
+   */
+  private getAllShared(): Record<string, CacheEntry> {
+    const now = Date.now()
+    const result: Record<string, CacheEntry> = {}
+
+    for (const [key, entry] of this.sharedCache.entries()) {
+      // Skip expired entries
+      if (entry.expireAt && now > entry.expireAt) {
+        this.sharedCache.delete(key)
+        continue
+      }
+      result[key] = entry
+    }
+
+    return result
+  }
+
   // ============ Persist Cache Interface (Reserved) ============
 
   // TODO: Implement persist cache in future
@@ -180,10 +297,32 @@ export class CacheService {
     // Handle cache sync broadcast from renderer
     ipcMain.on(IpcChannel.Cache_Sync, (event, message: CacheSyncMessage) => {
       const senderWindowId = BrowserWindow.fromWebContents(event.sender)?.id
+
+      // Update Main's sharedCache when receiving shared type sync
+      if (message.type === 'shared') {
+        if (message.value === undefined) {
+          // Handle deletion
+          this.sharedCache.delete(message.key)
+        } else {
+          // Handle set - use expireAt directly (absolute timestamp)
+          const entry: CacheEntry = {
+            value: message.value,
+            expireAt: message.expireAt
+          }
+          this.sharedCache.set(message.key, entry)
+        }
+      }
+
+      // Broadcast to other windows
       this.broadcastSync(message, senderWindowId)
       logger.verbose(`Broadcasted cache sync: ${message.type}:${message.key}`)
     })
 
+    // Handle getAllShared request for renderer initialization
+    ipcMain.handle(IpcChannel.Cache_GetAllShared, () => {
+      return this.getAllShared()
+    })
+
     logger.debug('Cache sync IPC handlers registered')
   }
 
@@ -197,11 +336,13 @@ export class CacheService {
       this.gcInterval = null
     }
 
-    // Clear cache
+    // Clear caches
     this.cache.clear()
+    this.sharedCache.clear()
 
     // Remove IPC handlers
     ipcMain.removeAllListeners(IpcChannel.Cache_Sync)
+    ipcMain.removeHandler(IpcChannel.Cache_GetAllShared)
 
     logger.debug('CacheService cleanup completed')
   }
diff --git a/src/preload/index.ts b/src/preload/index.ts
index 2a0cbfe366..f5f511b7ff 100644
--- a/src/preload/index.ts
+++ b/src/preload/index.ts
@@ -14,7 +14,7 @@ import type {
   WebviewKeyEvent
 } from '@shared/config/types'
 import type { MCPServerLogEntry } from '@shared/config/types'
-import type { CacheSyncMessage } from '@shared/data/cache/cacheTypes'
+import type { CacheEntry, CacheSyncMessage } from '@shared/data/cache/cacheTypes'
 import type {
   PreferenceDefaultScopeType,
   PreferenceKeyType,
@@ -580,7 +580,10 @@ const api = {
       const listener = (_: any, message: CacheSyncMessage) => callback(message)
       ipcRenderer.on(IpcChannel.Cache_Sync, listener)
       return () => ipcRenderer.off(IpcChannel.Cache_Sync, listener)
-    }
+    },
+
+    // Get all shared cache entries from Main for initialization sync
+    getAllShared: (): Promise<Record<string, CacheEntry>> => ipcRenderer.invoke(IpcChannel.Cache_GetAllShared)
   },
 
   // PreferenceService related APIs
diff --git a/src/renderer/src/data/CacheService.ts b/src/renderer/src/data/CacheService.ts
index 7fe9a2d7a7..1e61ce1ab7 100644
--- a/src/renderer/src/data/CacheService.ts
+++ b/src/renderer/src/data/CacheService.ts
@@ -21,10 +21,10 @@ import { loggerService } from '@logger'
 import type {
   RendererPersistCacheKey,
   RendererPersistCacheSchema,
+  SharedCacheKey,
+  SharedCacheSchema,
   UseCacheKey,
-  UseCacheSchema,
-  UseSharedCacheKey,
-  UseSharedCacheSchema
+  UseCacheSchema
 } from '@shared/data/cache/cacheSchemas'
 import { DefaultRendererPersistCache } from '@shared/data/cache/cacheSchemas'
 import type { CacheEntry, CacheSubscriber, CacheSyncMessage } from '@shared/data/cache/cacheTypes'
@@ -66,6 +66,10 @@ export class CacheService {
   private persistSaveTimer?: NodeJS.Timeout
   private persistDirty = false
 
+  // Shared cache ready state for initialization sync
+  private sharedCacheReady = false
+  private sharedCacheReadyCallbacks: Array<() => void> = []
+
   private constructor() {
     this.initialize()
   }
@@ -87,6 +91,10 @@ export class CacheService {
     this.loadPersistCache()
     this.setupIpcListeners()
     this.setupWindowUnloadHandler()
+
+    // Async sync SharedCache from Main (does not block initialization)
+    this.syncSharedCacheFromMain()
+
     logger.debug('CacheService initialized')
   }
 
@@ -279,7 +287,7 @@ export class CacheService {
    * @param key - Schema-defined shared cache key
    * @returns True if key has TTL configured
    */
-  hasSharedTTL<K extends UseSharedCacheKey>(key: K): boolean {
+  hasSharedTTL<K extends SharedCacheKey>(key: K): boolean {
     const entry = this.sharedCache.get(key)
     return entry?.expireAt !== undefined
   }
@@ -289,7 +297,7 @@ export class CacheService {
    * @param key - Dynamic shared cache key
    * @returns True if key has TTL configured
    */
-  hasSharedTTLCasual(key: Exclude<string, UseSharedCacheKey>): boolean {
+  hasSharedTTLCasual(key: Exclude<string, SharedCacheKey>): boolean {
     const entry = this.sharedCache.get(key)
     return entry?.expireAt !== undefined
   }
@@ -301,7 +309,7 @@ export class CacheService {
    * @param key - Schema-defined shared cache key
    * @returns Cached value or undefined if not found or expired
    */
-  getShared<K extends UseSharedCacheKey>(key: K): UseSharedCacheSchema[K] | undefined {
+  getShared<K extends SharedCacheKey>(key: K): SharedCacheSchema[K] | undefined {
     return this.getSharedInternal(key)
   }
 
@@ -310,7 +318,7 @@ export class CacheService {
    * @param key - Dynamic shared cache key (e.g., `window:${id}`)
    * @returns Cached value or undefined if not found or expired
    */
-  getSharedCasual<T>(key: Exclude<string, UseSharedCacheKey>): T | undefined {
+  getSharedCasual<T>(key: Exclude<string, SharedCacheKey>): T | undefined {
     return this.getSharedInternal(key)
   }
 
@@ -337,7 +345,7 @@ export class CacheService {
    * @param value - Value to cache (type inferred from schema)
    * @param ttl - Time to live in milliseconds (optional)
    */
-  setShared<K extends UseSharedCacheKey>(key: K, value: UseSharedCacheSchema[K], ttl?: number): void {
+  setShared<K extends SharedCacheKey>(key: K, value: SharedCacheSchema[K], ttl?: number): void {
     this.setSharedInternal(key, value, ttl)
   }
 
@@ -347,7 +355,7 @@ export class CacheService {
    * @param value - Value to cache
    * @param ttl - Time to live in milliseconds (optional)
    */
-  setSharedCasual<T>(key: Exclude<string, UseSharedCacheKey>, value: T, ttl?: number): void {
+  setSharedCasual<T>(key: Exclude<string, SharedCacheKey>, value: T, ttl?: number): void {
     this.setSharedInternal(key, value, ttl)
   }
 
@@ -356,11 +364,11 @@ export class CacheService {
    */
   private setSharedInternal(key: string, value: any, ttl?: number): void {
     const existingEntry = this.sharedCache.get(key)
+    const newExpireAt = ttl ? Date.now() + ttl : undefined
 
     // Value comparison optimization
     if (existingEntry && Object.is(existingEntry.value, value)) {
       // Value is same, only update TTL if needed
-      const newExpireAt = ttl ? Date.now() + ttl : undefined
       if (!Object.is(existingEntry.expireAt, newExpireAt)) {
         existingEntry.expireAt = newExpireAt
         logger.verbose(`Updated TTL for shared cache key "${key}"`)
@@ -369,7 +377,7 @@ export class CacheService {
           type: 'shared',
           key,
           value,
-          ttl
+          expireAt: newExpireAt // Use absolute timestamp for precise sync
         })
       } else {
         logger.verbose(`Skipped shared cache update for key "${key}" - value and TTL unchanged`)
@@ -379,7 +387,7 @@ export class CacheService {
 
     const entry: CacheEntry = {
       value,
-      expireAt: ttl ? Date.now() + ttl : undefined
+      expireAt: newExpireAt
     }
 
     // Update local copy first
@@ -391,7 +399,7 @@ export class CacheService {
       type: 'shared',
       key,
       value,
-      ttl
+      expireAt: newExpireAt // Use absolute timestamp for precise sync
     })
     logger.verbose(`Updated shared cache for key "${key}"`)
   }
@@ -401,7 +409,7 @@ export class CacheService {
    * @param key - Schema-defined shared cache key
    * @returns True if key exists and is valid, false otherwise
    */
-  hasShared<K extends UseSharedCacheKey>(key: K): boolean {
+  hasShared<K extends SharedCacheKey>(key: K): boolean {
     return this.hasSharedInternal(key)
   }
 
@@ -410,7 +418,7 @@ export class CacheService {
    * @param key - Dynamic shared cache key
    * @returns True if key exists and is valid, false otherwise
    */
-  hasSharedCasual(key: Exclude<string, UseSharedCacheKey>): boolean {
+  hasSharedCasual(key: Exclude<string, SharedCacheKey>): boolean {
     return this.hasSharedInternal(key)
   }
 
@@ -436,7 +444,7 @@ export class CacheService {
    * @param key - Schema-defined shared cache key
    * @returns True if deletion succeeded, false if key is protected by active hooks
    */
-  deleteShared<K extends UseSharedCacheKey>(key: K): boolean {
+  deleteShared<K extends SharedCacheKey>(key: K): boolean {
     return this.deleteSharedInternal(key)
   }
 
@@ -445,7 +453,7 @@ export class CacheService {
    * @param key - Dynamic shared cache key
    * @returns True if deletion succeeded, false if key is protected by active hooks
    */
-  deleteSharedCasual(key: Exclude<string, UseSharedCacheKey>): boolean {
+  deleteSharedCasual(key: Exclude<string, SharedCacheKey>): boolean {
     return this.deleteSharedInternal(key)
   }
 
@@ -557,6 +565,91 @@ export class CacheService {
     this.activeHooks.delete(key)
   }
 
+  // ============ Shared Cache Ready State Management ============
+
+  /**
+   * Check if shared cache has finished initial sync from Main
+   * @returns True if shared cache is ready
+   */
+  isSharedCacheReady(): boolean {
+    return this.sharedCacheReady
+  }
+
+  /**
+   * Register a callback to be called when shared cache is ready
+   * If already ready, callback is invoked immediately
+   * @param callback - Function to call when ready
+   * @returns Unsubscribe function
+   */
+  onSharedCacheReady(callback: () => void): () => void {
+    if (this.sharedCacheReady) {
+      callback()
+      return () => {}
+    }
+
+    this.sharedCacheReadyCallbacks.push(callback)
+    return () => {
+      const idx = this.sharedCacheReadyCallbacks.indexOf(callback)
+      if (idx >= 0) {
+        this.sharedCacheReadyCallbacks.splice(idx, 1)
+      }
+    }
+  }
+
+  /**
+   * Mark shared cache as ready and notify all waiting callbacks
+   */
+  private markSharedCacheReady(): void {
+    this.sharedCacheReady = true
+    this.sharedCacheReadyCallbacks.forEach((cb) => cb())
+    this.sharedCacheReadyCallbacks = []
+  }
+
+  /**
+   * Sync shared cache from Main process during initialization
+   * Uses Main-priority override strategy for conflict resolution
+   */
+  private async syncSharedCacheFromMain(): Promise<void> {
+    if (!window.api?.cache?.getAllShared) {
+      logger.warn('Cache getAllShared API not available')
+      this.markSharedCacheReady()
+      return
+    }
+
+    try {
+      const allShared = await window.api.cache.getAllShared()
+      let syncedCount = 0
+
+      for (const [key, entry] of Object.entries(allShared)) {
+        // Skip expired entries
+        if (entry.expireAt && Date.now() > entry.expireAt) {
+          continue
+        }
+
+        const existingEntry = this.sharedCache.get(key)
+
+        // Compare value and expireAt to determine if update is needed
+        const valueChanged = !existingEntry || !Object.is(existingEntry.value, entry.value)
+        const ttlChanged = !existingEntry || !Object.is(existingEntry.expireAt, entry.expireAt)
+
+        if (valueChanged || ttlChanged) {
+          // Main-priority override: always use Main's value
+          this.sharedCache.set(key, entry)
+          this.notifySubscribers(key) // Only notify on actual change
+          syncedCount++
+        }
+      }
+
+      logger.debug(
+        `Synced ${syncedCount} changed shared cache entries from Main (total: ${Object.keys(allShared).length})`
+      )
+    } catch (error) {
+      logger.error('Failed to sync shared cache from Main:', error as Error)
+    } finally {
+      this.markSharedCacheReady()
+    }
+  }
+
   // ============ Subscription Management ============
 
   /**
@@ -746,10 +839,10 @@ export class CacheService {
           // Handle deletion
           this.sharedCache.delete(message.key)
         } else {
-          // Handle set
+          // Handle set - use expireAt directly (absolute timestamp from sender)
           const entry: CacheEntry = {
             value: message.value,
-            expireAt: message.ttl ? Date.now() + message.ttl : undefined
+            expireAt: message.expireAt
           }
           this.sharedCache.set(message.key, entry)
         }
diff --git a/src/renderer/src/data/hooks/useCache.ts b/src/renderer/src/data/hooks/useCache.ts
index 7689b62f32..00198afd2c 100644
--- a/src/renderer/src/data/hooks/useCache.ts
+++ b/src/renderer/src/data/hooks/useCache.ts
@@ -3,12 +3,12 @@ import { loggerService } from '@logger'
 import type {
   RendererPersistCacheKey,
   RendererPersistCacheSchema,
+  SharedCacheKey,
+  SharedCacheSchema,
   UseCacheKey,
-  UseCacheSchema,
-  UseSharedCacheKey,
-  UseSharedCacheSchema
+  UseCacheSchema
 } from '@shared/data/cache/cacheSchemas'
-import { DefaultUseCache, DefaultUseSharedCache } from '@shared/data/cache/cacheSchemas'
+import { DefaultSharedCache, DefaultUseCache } from '@shared/data/cache/cacheSchemas'
 import { useCallback, useEffect, useSyncExternalStore } from 'react'
 const logger = loggerService.withContext('useCache')
 
@@ -121,10 +121,10 @@ export function useCache<K extends UseCacheKey>(
  * setWindowCount(3)
  * ```
  */
-export function useSharedCache<K extends UseSharedCacheKey>(
+export function useSharedCache<K extends SharedCacheKey>(
   key: K,
-  initValue?: UseSharedCacheSchema[K]
-): [UseSharedCacheSchema[K], (value: UseSharedCacheSchema[K]) => void] {
+  initValue?: SharedCacheSchema[K]
+): [SharedCacheSchema[K], (value: SharedCacheSchema[K]) => void] {
   /**
    * Subscribe to shared cache changes using React's useSyncExternalStore
    * This ensures the component re-renders when the shared cache value changes
@@ -145,7 +145,7 @@ export function useSharedCache<K extends UseSharedCacheKey>(
     }
 
     if (initValue === undefined) {
-      cacheService.setShared(key, DefaultUseSharedCache[key])
+      cacheService.setShared(key, DefaultSharedCache[key])
     } else {
       cacheService.setShared(key, initValue)
     }
@@ -178,13 +178,13 @@ export function useSharedCache<K extends UseSharedCacheKey>(
    * @param newValue - New value to store in shared cache
    */
   const setValue = useCallback(
-    (newValue: UseSharedCacheSchema[K]) => {
+    (newValue: SharedCacheSchema[K]) => {
       cacheService.setShared(key, newValue)
     },
     [key]
   )
 
-  return [value ?? initValue ?? DefaultUseSharedCache[key], setValue]
+  return [value ?? initValue ?? DefaultSharedCache[key], setValue]
 }
 
 /**
diff --git a/tests/__mocks__/renderer/CacheService.ts b/tests/__mocks__/renderer/CacheService.ts
index 653c0643d6..fbbdc10a25 100644
--- a/tests/__mocks__/renderer/CacheService.ts
+++ b/tests/__mocks__/renderer/CacheService.ts
@@ -2,9 +2,9 @@ import type {
   RendererPersistCacheKey,
   RendererPersistCacheSchema,
   UseCacheKey,
-  UseSharedCacheKey
+  SharedCacheKey
 } from '@shared/data/cache/cacheSchemas'
-import { DefaultRendererPersistCache, DefaultUseCache, DefaultUseSharedCache } from '@shared/data/cache/cacheSchemas'
+import { DefaultRendererPersistCache, DefaultUseCache, DefaultSharedCache } from '@shared/data/cache/cacheSchemas'
 import type { CacheSubscriber } from '@shared/data/cache/cacheTypes'
 import { vi } from 'vitest'
 
@@ -235,8 +235,8 @@ function getDefaultValueForKey(key: string): any {
 }
 
 function getDefaultSharedValueForKey(key: string): any {
-  if (key in DefaultUseSharedCache) {
-    return DefaultUseSharedCache[key as UseSharedCacheKey]
+  if (key in DefaultSharedCache) {
+    return DefaultSharedCache[key as SharedCacheKey]
   }
   return undefined
 }
diff --git a/tests/__mocks__/renderer/useCache.ts b/tests/__mocks__/renderer/useCache.ts
index 33f2f81203..77f9dd5dd1 100644
--- a/tests/__mocks__/renderer/useCache.ts
+++ b/tests/__mocks__/renderer/useCache.ts
@@ -3,10 +3,10 @@ import type {
   RendererPersistCacheSchema,
   UseCacheKey,
   UseCacheSchema,
-  UseSharedCacheKey,
-  UseSharedCacheSchema
+  SharedCacheKey,
+  SharedCacheSchema
 } from '@shared/data/cache/cacheSchemas'
-import { DefaultRendererPersistCache, DefaultUseCache, DefaultUseSharedCache } from '@shared/data/cache/cacheSchemas'
+import { DefaultRendererPersistCache, DefaultUseCache, DefaultSharedCache } from '@shared/data/cache/cacheSchemas'
 import { vi } from 'vitest'
 
 /**
@@ -16,7 +16,7 @@ import { vi } from 'vitest'
 
 // Mock cache state storage
 const mockMemoryCache = new Map<UseCacheKey, any>()
-const mockSharedCache = new Map<UseSharedCacheKey, any>()
+const mockSharedCache = new Map<SharedCacheKey, any>()
 const mockPersistCache = new Map<RendererPersistCacheKey, any>()
 
 // Initialize caches with defaults
@@ -24,8 +24,8 @@ Object.entries(DefaultUseCache).forEach(([key, value]) => {
   mockMemoryCache.set(key as UseCacheKey, value)
 })
 
-Object.entries(DefaultUseSharedCache).forEach(([key, value]) => {
-  mockSharedCache.set(key as UseSharedCacheKey, value)
+Object.entries(DefaultSharedCache).forEach(([key, value]) => {
+  mockSharedCache.set(key as SharedCacheKey, value)
 })
 
 Object.entries(DefaultRendererPersistCache).forEach(([key, value]) => {
@@ -34,7 +34,7 @@ Object.entries(DefaultRendererPersistCache).forEach(([key, value]) => {
 
 // Mock subscribers for cache changes
 const mockMemorySubscribers = new Map<UseCacheKey, Set<() => void>>()
-const mockSharedSubscribers = new Map<UseSharedCacheKey, Set<() => void>>()
+const mockSharedSubscribers = new Map<SharedCacheKey, Set<() => void>>()
 const mockPersistSubscribers = new Map<RendererPersistCacheKey, Set<() => void>>()
 
 // Helper functions to notify subscribers
@@ -51,7 +51,7 @@ const notifyMemorySubscribers = (key: UseCacheKey) => {
   }
 }
 
-const notifySharedSubscribers = (key: UseSharedCacheKey) => {
+const notifySharedSubscribers = (key: SharedCacheKey) => {
   const subscribers = mockSharedSubscribers.get(key)
   if (subscribers) {
     subscribers.forEach((callback) => {
@@ -108,21 +108,21 @@ export const mockUseCache = vi.fn(
  * Mock useSharedCache hook (shared cache)
  */
 export const mockUseSharedCache = vi.fn(
-  <K extends UseSharedCacheKey>(
+  <K extends SharedCacheKey>(
     key: K,
-    initValue?: UseSharedCacheSchema[K]
-  ): [UseSharedCacheSchema[K], (value: UseSharedCacheSchema[K]) => void] => {
+    initValue?: SharedCacheSchema[K]
+  ): [SharedCacheSchema[K], (value: SharedCacheSchema[K]) => void] => {
     // Get current value
     let currentValue = mockSharedCache.get(key)
     if (currentValue === undefined) {
-      currentValue = initValue ?? DefaultUseSharedCache[key]
+      currentValue = initValue ?? DefaultSharedCache[key]
       if (currentValue !== undefined) {
         mockSharedCache.set(key, currentValue)
       }
     }
 
     // Mock setValue function
-    const setValue = vi.fn((value: UseSharedCacheSchema[K]) => {
+    const setValue = vi.fn((value: SharedCacheSchema[K]) => {
       mockSharedCache.set(key, value)
       notifySharedSubscribers(key)
     })
@@ -188,8 +188,8 @@ export const MockUseCacheUtils = {
       mockMemoryCache.set(key as UseCacheKey, value)
     })
 
-    Object.entries(DefaultUseSharedCache).forEach(([key, value]) => {
-      mockSharedCache.set(key as UseSharedCacheKey, value)
+    Object.entries(DefaultSharedCache).forEach(([key, value]) => {
+      mockSharedCache.set(key as SharedCacheKey, value)
     })
 
     Object.entries(DefaultRendererPersistCache).forEach(([key, value]) => {
@@ -220,7 +220,7 @@ export const MockUseCacheUtils = {
   /**
    * Set shared cache value for testing
    */
-  setSharedCacheValue: <K extends UseSharedCacheKey>(key: K, value: UseSharedCacheSchema[K]) => {
+  setSharedCacheValue: <K extends SharedCacheKey>(key: K, value: SharedCacheSchema[K]) => {
     mockSharedCache.set(key, value)
     notifySharedSubscribers(key)
   },
@@ -228,8 +228,8 @@ export const MockUseCacheUtils = {
   /**
    * Get shared cache value
    */
-  getSharedCacheValue: <K extends UseSharedCacheKey>(key: K): UseSharedCacheSchema[K] => {
-    return mockSharedCache.get(key) ?? DefaultUseSharedCache[key]
+  getSharedCacheValue: <K extends SharedCacheKey>(key: K): SharedCacheSchema[K] => {
+    return mockSharedCache.get(key) ?? DefaultSharedCache[key]
   },
 
   /**
@@ -252,7 +252,7 @@ export const MockUseCacheUtils = {
    */
   setMultipleCacheValues: (values: {
     memory?: Array<[UseCacheKey, any]>
-    shared?: Array<[UseSharedCacheKey, any]>
+    shared?: Array<[SharedCacheKey, any]>
     persist?: Array<[RendererPersistCacheKey, any]>
   }) => {
     values.memory?.forEach(([key, value]) => {
@@ -310,10 +310,10 @@ export const MockUseCacheUtils = {
   /**
    * Mock shared cache hook to return specific value for a key
    */
-  mockSharedCacheReturn: <K extends UseSharedCacheKey>(
+  mockSharedCacheReturn: <K extends SharedCacheKey>(
     key: K,
-    value: UseSharedCacheSchema[K],
-    setValue?: (value: UseSharedCacheSchema[K]) => void
+    value: SharedCacheSchema[K],
+    setValue?: (value: SharedCacheSchema[K]) => void
   ) => {
     mockUseSharedCache.mockImplementation((cacheKey, initValue) => {
       if (cacheKey === key) {
@@ -321,7 +321,7 @@ export const MockUseCacheUtils = {
       }
 
       // Default behavior for other keys
-      const defaultValue = mockSharedCache.get(cacheKey) ?? initValue ?? DefaultUseSharedCache[cacheKey]
+      const defaultValue = mockSharedCache.get(cacheKey) ?? initValue ?? DefaultSharedCache[cacheKey]
       return [defaultValue, vi.fn()]
     })
   },
@@ -368,7 +368,7 @@ export const MockUseCacheUtils = {
   /**
    * Add subscriber for shared cache changes
    */
-  addSharedSubscriber: (key: UseSharedCacheKey, callback: () => void): (() => void) => {
+  addSharedSubscriber: (key: SharedCacheKey, callback: () => void): (() => void) => {
     if (!mockSharedSubscribers.has(key)) {
       mockSharedSubscribers.set(key, new Set())
     }