fix: skip opencode undo when message has zero output

Prevents error when undoing messages that produced no output.
Checks for reply, partialOutput, or done status before sending
/undo command to opencode.

chat/server.js

@@ -17334,21 +17334,28 @@ async function handleUndoMessage(req, res, sessionId, messageId, userId) {
   }
 
   try {
-    log('Sending undo command to opencode', { sessionId, messageId, opencodeSessionId: session.opencodeSessionId });
+    // Check if message had any output - if not, skip the opencode undo
+    const hasOutput = !!(message.reply || message.partialOutput) || message.status === 'done';
 
-    const cliCommand = resolveCliCommand('opencode');
+    if (hasOutput) {
-    const args = ['--message', '/undo'];
+      log('Sending undo command to opencode', { sessionId, messageId, opencodeSessionId: session.opencodeSessionId });
 
-    // Add session if we have one
+      const cliCommand = resolveCliCommand('opencode');
-    if (session.opencodeSessionId) {
+      const args = ['--message', '/undo'];
-      args.push('--session', session.opencodeSessionId);
+
+      // Add session if we have one
+      if (session.opencodeSessionId) {
+        args.push('--session', session.opencodeSessionId);
+      }
+
+      await runCommand(cliCommand, args, {
+        cwd: session.workspaceDir || REPO_ROOT,
+        timeout: 30000
+      });
+    } else {
+      log('Skipping undo command - message had zero output', { sessionId, messageId });
     }
 
-    await runCommand(cliCommand, args, {
-      cwd: session.workspaceDir || REPO_ROOT,
-      timeout: 30000
-    });
-
     // Clear todos from the message when undone
     if (message.todos) {
       const todoCount = message.todos.length;