fix(desktop): prevent backend zombie process and IPC listener leaks

desktop/src/renderer/src/App.tsx

@@ -34,7 +34,7 @@ const App: React.FC = () => {
 
   // Handle app-menu / shortcut actions forwarded from the main process.
   useEffect(() => {
-    window.electronAPI?.onMenuAction?.((action) => {
+    const off = window.electronAPI?.onMenuAction?.((action) => {
       if (action === 'new-chat') {
         useSessionStore.getState().newSession()
         navigate('/')
@@ -42,6 +42,7 @@ const App: React.FC = () => {
         navigate('/settings')
       }
     })
+    return off
   }, [navigate])
 
   const handleLangChange = useCallback(() => forceUpdate((n) => n + 1), [])

desktop/src/renderer/src/hooks/useBackend.ts

@@ -26,6 +26,7 @@ export function useBackend() {
 
   useEffect(() => {
     let cancelled = false
+    let offStatus: (() => void) | undefined
     const api = window.electronAPI
 
     const startPolling = async (port: number) => {
@@ -62,7 +63,7 @@ export function useBackend() {
         startPolling(p)
       })
 
-      api.onBackendStatus((data) => {
+      offStatus = api.onBackendStatus((data) => {
         if (data.status === 'ready' && data.port) {
           setState({ status: 'ready', port: data.port })
           if (pollingRef.current) {
@@ -82,6 +83,7 @@ export function useBackend() {
       if (pollingRef.current) {
         clearTimeout(pollingRef.current)
       }
+      offStatus?.()
     }
   }, [probeBackend])
 

desktop/src/renderer/src/layout/WindowControls.tsx

@@ -11,7 +11,8 @@ const WindowControls: React.FC = () => {
 
   useEffect(() => {
     api?.windowIsMaximized().then(setMaximized)
-    api?.onMaximizeChange(setMaximized)
+    const off = api?.onMaximizeChange(setMaximized)
+    return off
   }, [api])
 
   if (api?.platform === 'darwin') return null

desktop/src/renderer/src/types.ts

@@ -8,14 +8,15 @@ export interface ElectronAPI {
   restartBackend: () => Promise<boolean>
   selectDirectory: () => Promise<string | null>
   selectFile: (filters?: { name: string; extensions: string[] }[]) => Promise<string | null>
-  onBackendStatus: (callback: (data: BackendStatusEvent) => void) => void
-  onBackendLog: (callback: (line: string) => void) => void
+  // Listener registrars return an unsubscribe fn for cleanup.
+  onBackendStatus: (callback: (data: BackendStatusEvent) => void) => () => void
+  onBackendLog: (callback: (line: string) => void) => () => void
   windowMinimize: () => Promise<void>
   windowMaximize: () => Promise<boolean>
   windowClose: () => Promise<void>
   windowIsMaximized: () => Promise<boolean>
-  onMaximizeChange: (callback: (maximized: boolean) => void) => void
-  onMenuAction?: (callback: (action: string) => void) => void
+  onMaximizeChange: (callback: (maximized: boolean) => void) => () => void
+  onMenuAction?: (callback: (action: string) => void) => () => void
   platform: string
 }