diff --git a/chat/server.js b/chat/server.js
index 25a7d4f..1e12232 100644
--- a/chat/server.js
+++ b/chat/server.js
@@ -17354,6 +17354,19 @@ async function handleUndoMessage(req, res, sessionId, messageId, userId) {
       });
     } else {
       log('Skipping undo command - message had zero output', { sessionId, messageId });
+      
+      // If the message failed/had error, reset the opencode session to ensure fresh start
+      if (message.error || message.status === 'error') {
+        log('Resetting opencode session due to failed message', { 
+          sessionId, 
+          messageId, 
+          previousSessionId: session.opencodeSessionId,
+          messageStatus: message.status,
+          hasError: !!message.error
+        });
+        session.opencodeSessionId = null;
+        session.initialOpencodeSessionId = null;
+      }
     }
 
     // Clear todos from the message when undone