fix: clean up event listeners and timers in React hooks

client/src/components/ui/CopyButton.tsx

@@ -1,4 +1,4 @@
-import { useState } from 'react';
+import { useState, useRef, useEffect } from 'react';
 import { Copy, Check } from 'lucide-react';
 import toast from 'react-hot-toast';
 
@@ -11,6 +11,11 @@ interface CopyButtonProps {
 
 export function CopyButton({ text, label = 'Copied!', size = 14, className = '' }: CopyButtonProps) {
   const [copied, setCopied] = useState(false);
+  const timeoutRef = useRef<ReturnType<typeof setTimeout>>();
+
+  useEffect(() => {
+    return () => clearTimeout(timeoutRef.current);
+  }, []);
 
   const handleCopy = async () => {
     if (!navigator?.clipboard?.writeText) {
@@ -21,7 +26,8 @@ export function CopyButton({ text, label = 'Copied!', size = 14, className = ''
     if (success) {
       setCopied(true);
       toast.success(label);
-      setTimeout(() => setCopied(false), 2000);
+      clearTimeout(timeoutRef.current);
+      timeoutRef.current = setTimeout(() => setCopied(false), 2000);
     } else {
       toast.error('Failed to copy to clipboard');
     }

client/src/hooks/useSSE.ts

@@ -27,16 +27,24 @@ export function useSSE(
     // Proxy every named event through the ref so the EventSource instance
     // stays stable while handler implementations can change freely.
     const names = Object.keys(handlersRef.current);
+    const listeners: Array<[string, (e: Event) => void]> = [];
     for (const name of names) {
       if (name === 'message') {
         eventSource.onmessage = (e) => handlersRef.current.message?.(e);
       } else {
-        eventSource.addEventListener(name, (e) => {
+        const listener = (e: Event) => {
           handlersRef.current[name]?.(e as MessageEvent);
-        });
+        };
+        eventSource.addEventListener(name, listener);
+        listeners.push([name, listener]);
       }
     }
 
-    return () => eventSource.close();
+    return () => {
+      for (const [name, listener] of listeners) {
+        eventSource.removeEventListener(name, listener);
+      }
+      eventSource.close();
+    };
   }, [url]);
 }