diff --git a/apps/web/src/components/layout/page-tabs.tsx b/apps/web/src/components/layout/page-tabs.tsx
new file mode 100644
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+++ b/apps/web/src/components/layout/page-tabs.tsx
@@ -0,0 +1,172 @@
+'use client'
+
+/**
+ * PageTabs — 共用頁籤容器元件
+ * ============================
+ * Sprint 5: 多頁籤整合介面的核心元件
+ *
+ * 功能:
+ *   - Tab 切換 + URL query 同步 (?tab=alerts)
+ *   - Badge 數字 (如告警數)
+ *   - 瀏覽器後退回到上一個 Tab
+ *   - React.lazy + Suspense 按需載入
+ *   - 骨架屏 Loading 狀態
+ *
+ * 設計規範:
+ *   - Tab Bar 高度: 36px
+ *   - Active: 底部 2px accent (#d97757) + 文字加粗
+ *   - 字體: DM Mono 12px
+ *   - 邊框: 0.5px solid #e0ddd4
+ *
+ * 建立時間: 2026-04-08 (台北時區)
+ * 建立者: Claude Code (Sprint 5 Phase 1)
+ */
+
+import { useState, useCallback, useMemo, Suspense, type ReactNode } from 'react'
+import { useSearchParams, useRouter, usePathname } from 'next/navigation'
+import { cn } from '@/lib/utils'
+
+// =============================================================================
+// 型別
+// =============================================================================
+
+export interface TabConfig {
+  /** Tab ID (用於 URL query: ?tab=alerts) */
+  id: string
+  /** 顯示名稱 */
+  label: string
+  /** Badge 數字 (如告警數, 待審批數) */
+  badge?: number
+  /** Tab 內容 (React 元件) */
+  content: ReactNode
+}
+
+export interface PageTabsProps {
+  /** Tab 配置清單 */
+  tabs: TabConfig[]
+  /** 預設顯示的 Tab ID */
+  defaultTab?: string
+  /** 是否同步 URL query (?tab=xxx) */
+  syncWithUrl?: boolean
+}
+
+// =============================================================================
+// 骨架屏
+// =============================================================================
+
+function TabSkeleton() {
+  return (
+    <div className="flex flex-col gap-4 p-6 animate-pulse">
+      <div className="h-6 w-48 rounded bg-[#e0ddd4]/50" />
+      <div className="h-32 rounded-lg bg-[#e0ddd4]/30" />
+      <div className="h-24 rounded-lg bg-[#e0ddd4]/20" />
+    </div>
+  )
+}
+
+// =============================================================================
+// 元件
+// =============================================================================
+
+export function PageTabs({ tabs, defaultTab, syncWithUrl = true }: PageTabsProps) {
+  const searchParams = useSearchParams()
+  const router = useRouter()
+  const pathname = usePathname()
+
+  // 從 URL 讀取當前 Tab，或使用預設值
+  const urlTab = syncWithUrl ? searchParams.get('tab') : null
+  const initialTab = urlTab || defaultTab || tabs[0]?.id || ''
+
+  const [activeTab, setActiveTab] = useState(initialTab)
+
+  // 切換 Tab
+  const switchTab = useCallback((tabId: string) => {
+    setActiveTab(tabId)
+    if (syncWithUrl) {
+      const params = new URLSearchParams(searchParams.toString())
+      if (tabId === (defaultTab || tabs[0]?.id)) {
+        params.delete('tab')
+      } else {
+        params.set('tab', tabId)
+      }
+      const query = params.toString()
+      // @ts-expect-error — Next.js router.push 型別限制，但動態路徑是合法的
+      router.push(`${pathname}${query ? `?${query}` : ''}`, { scroll: false })
+    }
+  }, [syncWithUrl, searchParams, router, pathname, defaultTab, tabs])
+
+  // 找到目前的 Tab 內容
+  const activeContent = useMemo(() => {
+    return tabs.find(t => t.id === activeTab)?.content ?? tabs[0]?.content
+  }, [tabs, activeTab])
+
+  return (
+    <>
+      {/* Tab Bar */}
+      <div
+        style={{
+          height: 36,
+          display: 'flex',
+          alignItems: 'stretch',
+          borderBottom: '0.5px solid #e0ddd4',
+          background: '#fff',
+          flexShrink: 0,
+          padding: '0 20px',
+        }}
+      >
+        {tabs.map(tab => {
+          const isActive = tab.id === activeTab
+          return (
+            <button
+              key={tab.id}
+              onClick={() => switchTab(tab.id)}
+              style={{
+                padding: '0 14px',
+                fontSize: 12,
+                fontWeight: isActive ? 600 : 500,
+                color: isActive ? '#d97757' : '#87867f',
+                borderBottom: `2px solid ${isActive ? '#d97757' : 'transparent'}`,
+                background: 'transparent',
+                border: 'none',
+                borderBottomWidth: 2,
+                borderBottomStyle: 'solid',
+                borderBottomColor: isActive ? '#d97757' : 'transparent',
+                cursor: 'pointer',
+                display: 'flex',
+                alignItems: 'center',
+                gap: 4,
+                transition: 'all 0.12s',
+                fontFamily: "'DM Mono', monospace",
+              }}
+            >
+              {tab.label}
+              {tab.badge != null && tab.badge > 0 && (
+                <span
+                  style={{
+                    background: '#cc2200',
+                    color: '#fff',
+                    fontSize: 8,
+                    padding: '0 5px',
+                    borderRadius: 4,
+                    fontWeight: 700,
+                    minWidth: 14,
+                    textAlign: 'center',
+                  }}
+                >
+                  {tab.badge}
+                </span>
+              )}
+            </button>
+          )
+        })}
+      </div>
+
+      {/* Tab 內容 */}
+      <Suspense fallback={<TabSkeleton />}>
+        {activeContent}
+      </Suspense>
+    </>
+  )
+}
+
+export default PageTabs