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hooks/useMemoryUsage.ts

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+import { useState } from 'react'
+import { useInterval } from 'usehooks-ts'
+
+export type MemoryUsageStatus = 'normal' | 'high' | 'critical'
+
+export type MemoryUsageInfo = {
+  heapUsed: number
+  status: MemoryUsageStatus
+}
+
+const HIGH_MEMORY_THRESHOLD = 1.5 * 1024 * 1024 * 1024 // 1.5GB in bytes
+const CRITICAL_MEMORY_THRESHOLD = 2.5 * 1024 * 1024 * 1024 // 2.5GB in bytes
+
+/**
+ * Hook to monitor Node.js process memory usage.
+ * Polls every 10 seconds; returns null while status is 'normal'.
+ */
+export function useMemoryUsage(): MemoryUsageInfo | null {
+  const [memoryUsage, setMemoryUsage] = useState<MemoryUsageInfo | null>(null)
+
+  useInterval(() => {
+    const heapUsed = process.memoryUsage().heapUsed
+    const status: MemoryUsageStatus =
+      heapUsed >= CRITICAL_MEMORY_THRESHOLD
+        ? 'critical'
+        : heapUsed >= HIGH_MEMORY_THRESHOLD
+          ? 'high'
+          : 'normal'
+    setMemoryUsage(prev => {
+      // Bail when status is 'normal' — nothing is shown, so heapUsed is
+      // irrelevant and we avoid re-rendering the whole Notifications subtree
+      // every 10 seconds for the 99%+ of users who never reach 1.5GB.
+      if (status === 'normal') return prev === null ? prev : null
+      return { heapUsed, status }
+    })
+  }, 10_000)
+
+  return memoryUsage
+}