fix: focus lost when transitioning from immersive to markdown

js/src/features/compose/text-compose-step.tsx

@@ -30,8 +30,8 @@ interface TextComposeStepProps {
 const IMMERSIVE_CHAR_LIMIT = 120;
 
 function getImmersiveTextStyle(length: number) {
-  if (length < 30) return { size: "text-5xl", weight: "font-semibold" };
-  if (length < 70) return { size: "text-3xl", weight: "font-semibold" };
+  if (length < 70) return { size: "text-5xl", weight: "font-semibold" };
+  if (length < 130) return { size: "text-3xl", weight: "font-semibold" };
   return { size: "text-2xl", weight: "font-normal" };
 }
 
@@ -118,13 +118,22 @@ export function TextComposeStep({
   }, [textContent]);
   const linkPreviews = useAllLinkMetadata(debouncedText);
 
+  const hasEnrichments = attachments.length > 0 || linkPreviews.length > 0;
+  const immersive = textContent.length < IMMERSIVE_CHAR_LIMIT && !hasEnrichments && !forceCardMode;
+
   useEffect(() => {
     if (!previewMode) {
       // Small timeout so the textarea is mounted before focusing
-      const t = setTimeout(() => textareaRef.current?.focus(), 0);
+      const t = setTimeout(() => {
+        const el = textareaRef.current;
+        if (el) {
+          el.focus();
+          el.selectionStart = el.selectionEnd = el.value.length;
+        }
+      }, 0);
       return () => clearTimeout(t);
     }
-  }, [previewMode, forceCardMode]);
+  }, [previewMode, forceCardMode, immersive]);
 
   useEffect(() => {
     textareaRef.current?.focus();
@@ -146,9 +155,6 @@ export function TextComposeStep({
     [onCancel, onAdvance, textContent],
   );
 
-  const hasEnrichments = attachments.length > 0 || linkPreviews.length > 0;
-  const immersive = textContent.length < IMMERSIVE_CHAR_LIMIT && !hasEnrichments && !forceCardMode;
-
   const strip = (
     <AttachmentStrip
       attachments={attachments}