fix: forward textarea ref for auto resize

frontend/src/components/chat/ChatPanel.tsx

@@ -44,7 +44,12 @@ export default function ChatPanel({ activeDoc, onCitationClick }: Props) {
     if (!textarea) return;
 
     textarea.style.height = "auto";
-    const maxHeight = 128;
+    const computedMaxHeight = Number.parseFloat(
+      window.getComputedStyle(textarea).maxHeight
+    );
+    const maxHeight = Number.isFinite(computedMaxHeight)
+      ? computedMaxHeight
+      : textarea.scrollHeight;
     const nextHeight = Math.min(textarea.scrollHeight, maxHeight);
     textarea.style.height = `${nextHeight}px`;
     textarea.style.overflowY =

frontend/src/components/ui/textarea.tsx

@@ -2,9 +2,13 @@ import * as React from "react"
 
 import { cn } from "@/lib/utils"
 
-function Textarea({ className, ...props }: React.ComponentProps<"textarea">) {
+const Textarea = React.forwardRef<
+  HTMLTextAreaElement,
+  React.ComponentProps<"textarea">
+>(({ className, ...props }, ref) => {
   return (
     <textarea
+      ref={ref}
       data-slot="textarea"
       className={cn(
         "flex field-sizing-content min-h-16 w-full rounded-lg border border-input bg-transparent px-2.5 py-2 text-base transition-colors outline-none placeholder:text-muted-foreground focus-visible:border-ring focus-visible:ring-3 focus-visible:ring-ring/50 disabled:cursor-not-allowed disabled:bg-input/50 disabled:opacity-50 aria-invalid:border-destructive aria-invalid:ring-3 aria-invalid:ring-destructive/20 md:text-sm dark:bg-input/30 dark:disabled:bg-input/80 dark:aria-invalid:border-destructive/50 dark:aria-invalid:ring-destructive/40",
@@ -13,6 +17,8 @@ function Textarea({ className, ...props }: React.ComponentProps<"textarea">) {
       {...props}
     />
   )
-}
+})
+
+Textarea.displayName = "Textarea"
 
 export { Textarea }