diff --git a/cross_eval/agent.py b/cross_eval/agent.py
index f97d1f7..3844520 100644
--- a/cross_eval/agent.py
+++ b/cross_eval/agent.py
@@ -442,7 +442,10 @@ def invoke_agent_agentic(
             input_data = prompt
     else:
         # claude: use positional arg with a pointer to the task file
-        # (avoids OS arg length limits for large prompts)
+        # (avoids OS arg length limits for large prompts).
+        # Send empty stdin so Claude receives EOF and exits after processing
+        # instead of hanging in interactive mode waiting for more input.
+        input_data = ""
         cmd.append(
             f"Read the task file at {task_file} and execute all instructions in it. "
             f"Work only inside the current directory and do not modify files "