diff --git a/container/agent-runner/src/index.ts b/container/agent-runner/src/index.ts
index 05f73dd..543c5f5 100644
--- a/container/agent-runner/src/index.ts
+++ b/container/agent-runner/src/index.ts
@@ -272,7 +272,7 @@ function formatTranscriptMarkdown(messages: ParsedMessage[], title?: string | nu
   lines.push('');
 
   for (const msg of messages) {
-    const sender = msg.role === 'user' ? 'User' : (assistantName || 'AssistantNameMissing');
+    const sender = msg.role === 'user' ? 'User' : (assistantName || 'Assistant');
     const content = msg.content.length > 2000
       ? msg.content.slice(0, 2000) + '...'
       : msg.content;