currently we have start_mock_server not inside main. Moving it to main works

── Agent setup ───────────────────────────────────────────────────────

mock_server = _start_mock_server(port=9753)

serverless_coder = Agent(
name="serverless_coder",
model=settings.llm_model,
code_execution=CodeExecutionConfig(
executor=ServerlessCodeExecutor(
endpoint="http://127.0.0.1:9753/execute",
language="python",
timeout=15,
),
),
instructions=(
"You write Python code that runs on a remote execution service. "
"Use the execute_code tool to run code remotely."
),
)

if name == "main":
### #mock_server = _start_mock_server(port=9753). -> ADD THIS
with AgentRuntime() as runtime:
print("--- Serverless Code Execution ---")
result = runtime.run(
serverless_coder,
"Calculate 2**100 and print the result.",
)
result.print_result()

This was a claude code suggested fix and it works.
Claude's reasoning:
Before: mock_server = _start_mock_server(9753) was outside. You start the script — port 9753 grabbed. Worker starts, re-imports the file, hits that same line, tries to grab 9753 again. Already taken → Address already in use → worker dies.

After: it's inside the if. You start the script — port grabbed once. Worker re-imports, reaches the if, sees it's false, skips it. No second bind. Worker lives.