diff --git a/chat/public/builder.js b/chat/public/builder.js
index b0e6417..510ae6c 100644
--- a/chat/public/builder.js
+++ b/chat/public/builder.js
@@ -323,14 +323,25 @@ async function redoMessage(msg, session) {
 
   // Case 1: Proceed with Build - undo first, then rebuild with plan content
   if (isProceedWithBuild) {
-    // First, send undo to revert any file changes
-    try {
-      await api(`/api/sessions/${session.id}/messages/${msg.id}/undo`, {
-        method: 'POST',
-      });
-      setStatus('Undo complete, rebuilding...');
-    } catch (err) {
-      console.warn('Undo failed, continuing with redo:', err.message);
+    // Check if this is the first opencode message (nothing to undo yet)
+    const messageIndex = session.messages.findIndex(m => m.id === msg.id);
+    const hasPreviousOpencodeMessages = session.messages
+      .slice(0, messageIndex)
+      .some(m => m.cli === 'opencode');
+
+    // Only undo if there are previous opencode messages
+    if (hasPreviousOpencodeMessages) {
+      try {
+        await api(`/api/sessions/${session.id}/messages/${msg.id}/undo`, {
+          method: 'POST',
+        });
+        setStatus('Undo complete, rebuilding...');
+      } catch (err) {
+        console.warn('Undo failed, continuing with redo:', err.message);
+      }
+    } else {
+      console.log('First build message - skipping undo, proceeding directly to rebuild');
+      setStatus('Starting build...');
     }
 
     // Get the plan content - either stored on the message or try to extract from content