fix(dashboard): grow main chat composer height as message grows

Reorders ChatView's input handler to resize the textarea before the
controlled setMessageInput call (matching QuickChat) so the height
assignment lands in the same frame as the keystroke and isn't lost to
React 18 batching. Also adds a 40px floor to clampChatInputHeight so a
0-scrollHeight measurement can't collapse the composer to zero.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

packages/dashboard/app/components/ChatView.tsx

@@ -56,7 +56,10 @@ export interface ChatViewProps {
 const CHAT_INPUT_MAX_HEIGHT_PX = 640;
 
 export function clampChatInputHeight(scrollHeight: number): number {
-  return Math.min(scrollHeight, CHAT_INPUT_MAX_HEIGHT_PX);
+  // Floor matches QuickChat (clampQuickChatInputHeight) and the CSS min-height,
+  // so a 0-scrollHeight measurement (e.g. before layout) still yields a
+  // sensible inline height instead of collapsing the composer to 0.
+  return Math.max(40, Math.min(scrollHeight, CHAT_INPUT_MAX_HEIGHT_PX));
 }
 
 function formatRelativeTime(dateStr: string): string {
@@ -1983,6 +1986,13 @@ export function ChatView({ projectId, addToast, experimentalFeatures }: ChatView
     const nextValue = textarea.value;
     const cursorPos = textarea.selectionStart ?? nextValue.length;
 
+    // Resize BEFORE the state update so the textarea grows in the same frame
+    // the user typed in (matches QuickChat). Doing it after setMessageInput
+    // works in tests but can lose the height in production because React 18
+    // batches the state update and the controlled-component value reset can
+    // happen before our direct DOM height assignment lands.
+    resizeComposer(textarea);
+
     mentionCursorPosRef.current = cursorPos;
     setMessageInput(nextValue);
 
@@ -2003,8 +2013,6 @@ export function ChatView({ projectId, addToast, experimentalFeatures }: ChatView
     if (fileMention.mentionActive) {
       updateFileMentionPosition(textarea);
     }
-
-    resizeComposer(textarea);
   }, [updateMentionState, resizeComposer]);
 
   const handleInputSelectionChange = useCallback(