diff --git a/src/screens/REPL.tsx b/src/screens/REPL.tsx
index bcfd6a4d..4b15666b 100644
--- a/src/screens/REPL.tsx
+++ b/src/screens/REPL.tsx
@@ -793,20 +793,8 @@ export function REPL({
   // accepts, and only then is the REPL component mounted and this effect runs.
   // This ensures that plugin installations from repository and user settings only
   // happen after explicit user consent to trust the current working directory.
-  // We defer startup checks by STARTUP_CHECK_DELAY_MS and gate on
-  // promptTypingSuppressionActive so that plugin loading doesn't steal focus
-  // from the prompt during the vulnerable startup window (issue #363).
-  const startupChecksStartedRef = React.useRef(false)
-  useEffect(() => {
-    if (isRemoteSession) return
-    if (startupChecksStartedRef.current) return
-    const timer = setTimeout(() => {
-      if (!shouldRunStartupChecks(isRemoteSession, startupChecksStartedRef.current, promptTypingSuppressionActive)) return
-      startupChecksStartedRef.current = true
-      void performStartupChecks(setAppState)
-    }, STARTUP_CHECK_DELAY_MS)
-    return () => clearTimeout(timer)
-  }, [setAppState, isRemoteSession, promptTypingSuppressionActive])
+  // Deferring startup checks is handled below (after promptTypingSuppressionActive
+  // is declared) to avoid temporal dead zone issues.
 
   // Allow Claude in Chrome MCP to send prompts through MCP notifications
   // and sync permission mode changes to the Chrome extension
@@ -1349,6 +1337,21 @@ export function REPL({
   const inputValueRef = useRef(inputValue);
   inputValueRef.current = inputValue;
   const promptTypingSuppressionActive = isPromptTypingSuppressionActive(isPromptInputActive, inputValue);
+
+  // Defer startup checks by STARTUP_CHECK_DELAY_MS and gate on
+  // promptTypingSuppressionActive so that plugin loading doesn't steal focus
+  // from the prompt during the vulnerable startup window (issue #363).
+  const startupChecksStartedRef = React.useRef(false);
+  useEffect(() => {
+    if (isRemoteSession) return;
+    if (startupChecksStartedRef.current) return;
+    const timer = setTimeout(() => {
+      if (!shouldRunStartupChecks(isRemoteSession, startupChecksStartedRef.current, promptTypingSuppressionActive)) return;
+      startupChecksStartedRef.current = true;
+      void performStartupChecks(setAppState);
+    }, STARTUP_CHECK_DELAY_MS);
+    return () => clearTimeout(timer);
+  }, [setAppState, isRemoteSession, promptTypingSuppressionActive]);
   const insertTextRef = useRef<{
     insert: (text: string) => void;
     setInputWithCursor: (value: string, cursor: number) => void;
@@ -2072,14 +2075,14 @@ export function REPL({
     if (allowDialogsWithAnimation && showRemoteCallout) return 'remote-callout';
 
     // LSP plugin recommendation (lowest priority - non-blocking suggestion)
-  // Suppress during startup window to prevent stealing focus from the prompt (issue #363)
-  if (allowDialogsWithAnimation && lspRecommendation && startupChecksStartedRef.current) return 'lsp-recommendation';
+    // Suppress during startup window to prevent stealing focus from the prompt (issue #363)
+    if (allowDialogsWithAnimation && lspRecommendation && startupChecksStartedRef.current) return 'lsp-recommendation';
 
-  // Plugin hint from CLI/SDK stderr (same priority band as LSP rec)
-  if (allowDialogsWithAnimation && hintRecommendation && startupChecksStartedRef.current) return 'plugin-hint';
+    // Plugin hint from CLI/SDK stderr (same priority band as LSP rec)
+    if (allowDialogsWithAnimation && hintRecommendation && startupChecksStartedRef.current) return 'plugin-hint';
 
-  // Desktop app upsell (max 3 launches, lowest priority)
-  if (allowDialogsWithAnimation && showDesktopUpsellStartup && startupChecksStartedRef.current) return 'desktop-upsell';
+    // Desktop app upsell (max 3 launches, lowest priority)
+    if (allowDialogsWithAnimation && showDesktopUpsellStartup && startupChecksStartedRef.current) return 'desktop-upsell';
     return undefined;
   }
   const focusedInputDialog = getFocusedInputDialog();