fix(mobile): use selectionchange event for immediate text selection detection

Replace mouseup/touchend handlers with selectionchange event listener
for more reliable mobile text selection detection. This fixes the issue
where the highlight button required an extra tap to become active on
mobile devices.

- Extract selection checking logic into shared checkSelection function
- Use selectionchange event with requestAnimationFrame for immediate detection
- Remove onMouseUp and onTouchEnd props from VideoEmbedProcessor
- Simplify code by eliminating separate mouse/touch event handlers

src/components/ContentPanel.tsx

@@ -133,7 +133,7 @@ const ContentPanel: React.FC<ContentPanelProps> = ({
     return selectedUrl || `${title || ''}:${(markdown || html || '').length}`
   }, [selectedUrl, title, markdown, html])
 
-  const { contentRef, handleSelectionEnd } = useHighlightInteractions({
+  const { contentRef } = useHighlightInteractions({
     onHighlightClick,
     selectedHighlightId,
     onTextSelection,
@@ -815,8 +815,6 @@ const ContentPanel: React.FC<ContentPanelProps> = ({
                 html={finalHtml}
                 renderVideoLinksAsEmbeds={settings?.renderVideoLinksAsEmbeds === true}
                 className="reader-markdown"
-                onMouseUp={handleSelectionEnd}
-                onTouchEnd={handleSelectionEnd}
               />
             ) : (
               <div className="reader-markdown">
@@ -830,8 +828,6 @@ const ContentPanel: React.FC<ContentPanelProps> = ({
               html={finalHtml || html || ''}
               renderVideoLinksAsEmbeds={settings?.renderVideoLinksAsEmbeds === true}
               className="reader-html"
-              onMouseUp={handleSelectionEnd}
-              onTouchEnd={handleSelectionEnd}
             />
           )}
           

src/components/VideoEmbedProcessor.tsx

@@ -6,8 +6,6 @@ interface VideoEmbedProcessorProps {
   html: string
   renderVideoLinksAsEmbeds: boolean
   className?: string
-  onMouseUp?: (e: React.MouseEvent) => void
-  onTouchEnd?: (e: React.TouchEvent) => void
 }
 
 /**
@@ -17,9 +15,7 @@ interface VideoEmbedProcessorProps {
 const VideoEmbedProcessor = forwardRef<HTMLDivElement, VideoEmbedProcessorProps>(({
   html,
   renderVideoLinksAsEmbeds,
-  className,
+  className
-  onMouseUp,
-  onTouchEnd
 }, ref) => {
   // Process HTML and extract video URLs in a single pass to keep them in sync
   const { processedHtml, videoUrls } = useMemo(() => {
@@ -109,8 +105,6 @@ const VideoEmbedProcessor = forwardRef<HTMLDivElement, VideoEmbedProcessorProps>
         ref={ref}
         className={className}
         dangerouslySetInnerHTML={{ __html: processedHtml }}
-        onMouseUp={onMouseUp}
-        onTouchEnd={onTouchEnd}
       />
     )
   }
@@ -119,7 +113,7 @@ const VideoEmbedProcessor = forwardRef<HTMLDivElement, VideoEmbedProcessorProps>
   const parts = processedHtml.split(/(__VIDEO_EMBED_\d+__)/)
   
   return (
-    <div ref={ref} className={className} onMouseUp={onMouseUp} onTouchEnd={onTouchEnd}>
+    <div ref={ref} className={className}>
       {parts.map((part, index) => {
         const videoMatch = part.match(/^__VIDEO_EMBED_(\d+)__$/)
         if (videoMatch) {

src/hooks/useHighlightInteractions.ts

@@ -93,9 +93,8 @@ export const useHighlightInteractions = ({
     return () => clearTimeout(timeoutId)
   }, [selectedHighlightId, contentVersion])
 
-  // Handle text selection (works for both mouse and touch)
+  // Shared function to check and handle text selection
-  const handleSelectionEnd = useCallback(() => {
+  const checkSelection = useCallback(() => {
-    setTimeout(() => {
     const selection = window.getSelection()
     if (!selection || selection.rangeCount === 0) {
       onClearSelection?.()
@@ -110,9 +109,21 @@ export const useHighlightInteractions = ({
     } else {
       onClearSelection?.()
     }
-    }, 10)
   }, [onTextSelection, onClearSelection])
 
-  return { contentRef, handleSelectionEnd }
+  // Listen to selectionchange events for immediate detection (works reliably on mobile)
+  useEffect(() => {
+    const handleSelectionChange = () => {
+      // Use requestAnimationFrame to ensure selection is checked after browser updates
+      requestAnimationFrame(checkSelection)
+    }
+
+    document.addEventListener('selectionchange', handleSelectionChange)
+    return () => {
+      document.removeEventListener('selectionchange', handleSelectionChange)
+    }
+  }, [checkSelection])
+
+  return { contentRef }
 }