type ToolResultCache struct {
    cache *lru.Cache
    mu    sync.RWMutex
}

type CachedResult struct {
    Result    string
    CachedAt  time.Time
    TTL       time.Duration
}

type CacheKey struct {
    ToolName  string
    UserID    int32
    InputHash string
}

// 针对不同工具的 TTL 策略
var toolTTLs = map[string]time.Duration{
    "schedule_query": 30 * time.Second,  // 日程变化较少
    "memo_search":    5 * time.Minute,   // 笔记搜索结果稳定
    "find_free_time": 1 * time.Minute,   // 空闲时间需要较新
    "schedule_add":   0,                 // 不缓存写操作
    "schedule_update": 0,                // 不缓存写操作
}

// 当日程发生变更时，失效相关缓存
func (c *ToolResultCache) InvalidateScheduleCache(userID int32) {
    c.mu.Lock()
    defer c.mu.Unlock()
    
    c.cache.Remove(CacheKey{ToolName: "schedule_query", UserID: userID, ...})
    c.cache.Remove(CacheKey{ToolName: "find_free_time", UserID: userID, ...})
}