perf: guard Linear comment footer async state without effect

src/renderer/src/components/LinearItemDrawer.tsx

@@ -955,11 +955,10 @@ export function LinearIssueCommentFooter({
   const textareaRef = useRef<HTMLTextAreaElement>(null)
   const mountedRef = useRef(true)
 
-  useEffect(() => {
-    mountedRef.current = true
-    return () => {
-      mountedRef.current = false
-    }
+  const handleFooterRef = useCallback((node: HTMLDivElement | null): void => {
+    // Why: comment submission can resolve after the footer unmounts; the root
+    // ref keeps that completion from writing stale local state without an Effect.
+    mountedRef.current = node !== null
   }, [])
 
   const autoGrow = useCallback(() => {
@@ -1016,7 +1015,10 @@ export function LinearIssueCommentFooter({
 
   if (variant === 'linear-page') {
     return (
-      <div className="rounded-xl border border-border/70 bg-background shadow-xs">
+      <div
+        ref={handleFooterRef}
+        className="rounded-xl border border-border/70 bg-background shadow-xs"
+      >
         <textarea
           ref={textareaRef}
           value={body}
@@ -1051,7 +1053,10 @@ export function LinearIssueCommentFooter({
   }
 
   return (
-    <div className="flex items-end gap-2 border-t border-border/60 bg-background/40 px-4 py-3">
+    <div
+      ref={handleFooterRef}
+      className="flex items-end gap-2 border-t border-border/60 bg-background/40 px-4 py-3"
+    >
       <textarea
         ref={textareaRef}
         value={body}