Enable OpenAIResponsesCompactionSession to run in stateless mode #2333

async def customer_agent():
    redis_client = redis.get_async_client()
    
    try:
        redis_session = RedisSession(
            session_id="demo-session-1",
            redis_client=redis_client,
            ttl=60*60*24,
        )

        session = OpenAIResponsesCompactionSession(
            session_id="demo-session-1",
            underlying_session=redis_session,
            model="gpt-4.1",
            # Custom compaction trigger (default is 10 candidates)
            should_trigger_compaction=lambda ctx: len(ctx["compaction_candidate_items"]) >= 4,
        )
        agent = Agent(name="Assistant",
                      model="gpt-5.2",
                      tools=[],
                      model_settings=ModelSettings(store=False),
                      instructions="""
                                     Reply concisely. Keep answers to 1-2 sentences.
                                     """)

        prompts = [
            "What is the tallest mountain in the world?",
            "How tall is it in feet?",
            "When was it first climbed?",
            "Who was on that expedition?",
            "What country is the mountain in?",
        ]

        print("=== Compaction Session Example ===\n")

        for i, prompt in enumerate(prompts, 1):
            print(f"Turn {i}:")
            print(f"User: {prompt}")
            result = await Runner.run(agent, session=session, input=prompt)
            print(f"Assistant: {result.final_output}\n")

        # Show final session state
        items = await session.get_items()
        print("=== Final Session State ===")
        print(f"Total items: {len(items)}")
        for item in items:
            # Some inputs are stored as easy messages (only `role` and `content`).
            item_type = item.get("type") or ("message" if "role" in item else "unknown")
            if item_type == "compaction":
                print("  - compaction (encrypted content)")
            elif item_type == "message":
                role = item.get("role", "unknown")
                print(f"  - message ({role})")
            else:
                print(f"  - {item_type}")
    
    finally:
        # 确保 Redis 连接正确关闭
        await redis_client.aclose()

=== Compaction Session Example ===

Turn 1:
User: What is the tallest mountain in the world?
Assistant: Mount Everest is the tallest mountain in the world, rising about 8,849 meters (29,032 feet) above sea level.

Turn 2:
User: How tall is it in feet?
Assistant: Mount Everest is about **29,032 feet** tall above sea level.

Turn 3:
User: When was it first climbed?
Assistant: Mount Everest was first successfully climbed on **May 29, 1953**, by **Edmund Hillary** and **Tenzing Norgay**.

Turn 4:
User: Who was on that expedition?
Traceback (most recent call last):
  File "/Users/abc/www/new-test-gpt/index.py", line 135, in <module>
    asyncio.run(customer_agent())
  File "/Library/Frameworks/Python.framework/Versions/3.12/lib/python3.12/asyncio/runners.py", line 194, in run
    return runner.run(main)
           ^^^^^^^^^^^^^^^^
  File "/Library/Frameworks/Python.framework/Versions/3.12/lib/python3.12/asyncio/runners.py", line 118, in run
    return self._loop.run_until_complete(task)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Library/Frameworks/Python.framework/Versions/3.12/lib/python3.12/asyncio/base_events.py", line 664, in run_until_complete
    return future.result()
           ^^^^^^^^^^^^^^^
  File "/Users/abc/www/new-test-gpt/index.py", line 57, in customer_agent
    result = await Runner.run(agent, session=session, input=prompt)
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/abc/www/new-test-gpt/.venv/lib/python3.12/site-packages/agents/run.py", line 372, in run
    return await runner.run(
           ^^^^^^^^^^^^^^^^^
  File "/Users/abc/www/new-testgpt/.venv/lib/python3.12/site-packages/agents/run.py", line 753, in run
    await self._save_result_to_session(
  File "/Users/abc/www/new-test-gpt/.venv/lib/python3.12/site-packages/agents/run.py", line 2124, in _save_result_to_session
    await session.run_compaction({"response_id": response_id, "force": force_compaction})
  File "/Users/abc/www/new-test-gpt/.venv/lib/python3.12/site-packages/agents/memory/openai_responses_compaction_session.py", line 160, in run_compaction
    compacted = await self.client.responses.compact(
                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/abc/www/new-test-gpt/.venv/lib/python3.12/site-packages/openai/resources/responses/responses.py", line 3279, in compact
    return await self._post(
           ^^^^^^^^^^^^^^^^^
  File "/Users/abc/www/new-test-gpt/.venv/lib/python3.12/site-packages/openai/_base_client.py", line 1797, in post
    return await self.request(cast_to, opts, stream=stream, stream_cls=stream_cls)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/abc/www/new-test-gpt/.venv/lib/python3.12/site-packages/openai/_base_client.py", line 1597, in request
    raise self._make_status_error_from_response(err.response) from None
openai.BadRequestError: Error code: 400 - {'error': {'message': "Previous response with id 'resp_*****c38ac3' not found.", 'type': 'invalid_request_error', 'param': 'previous_response_id', 'code': 'previous_response_not_found'}}