OpenAIConversationsSession and OpenAIResponsesCompactionSession ignore set_default_openai_key()

从 src/agents/memory/openai_conversations_session.py 开始，查看第 21 行和第 50 行附近构建回退 AsyncOpenAI() 的位置，然后检查 src/agents/memory/openai_responses_compaction_session.py 第 196 行附近，以及 src/agents/models/openai_provider.py 中需要复制的 get_default_openai_key() 模式。在两个阶段分别运行 issue 中的复现脚本，然后运行 tests/memory。当两个会话都能报告 set_default_openai_key() 设置的密钥，无论是否设置了 OPENAI_API_KEY，即为完成。

Please read this first

• Have you read the docs? Yes
• Have you searched for related issues? Yes. Nothing covers it. #2164 is a feature request for several keys per run.

Describe the bug

set_default_openai_key() is documented as the key that "will be used instead of the OPENAI_API_KEY environment variable". OpenAIProvider honors it, and so do the voice provider and the Codex tool. OpenAIConversationsSession and OpenAIResponsesCompactionSession don't. When no default client is set, they build a bare AsyncOpenAI(), which reads only OPENAI_API_KEY. That causes two problems:

• When the key is set only through the SDK, OpenAIConversationsSession() raises OpenAIError: Missing credentials when it's constructed, and the compaction session raises on its first responses.compact call.
• When OPENAI_API_KEY is also set, the sessions quietly use the environment key while model calls use the SDK key. Conversation items and the billed responses.compact calls land in a different project or org than the run's responses.

Debug information

• Agents SDK version: main (e355d69), also 0.24.0
• Related library versions: openai 3.29.0
• Python version: 3.14.7
• Operating system: macOS
• Model and model provider: OpenAI
• Does the issue reproduce with the latest Agents SDK release? Yes
• Does the issue occur consistently or intermittently? Consistently

Repro steps

import os
os.environ.pop("OPENAI_API_KEY", None)  # key is configured only through the SDK

from agents import SQLiteSession, set_default_openai_key
from agents.memory import OpenAIConversationsSession, OpenAIResponsesCompactionSession
from agents.models.multi_provider import MultiProvider

set_default_openai_key("sk-from-set-default-openai-key")

def show(label, make):
    try:
        print(f"{label}:", make().api_key)
    except Exception as e:
        print(f"{label}:", type(e).__name__, "-", str(e)[:40])

for phase in ("SDK key only", "OPENAI_API_KEY also set"):
    if phase == "OPENAI_API_KEY also set":
        os.environ["OPENAI_API_KEY"] = "sk-other-project-from-env"
    print("--", phase)
    print("model client        :", MultiProvider().get_model("gpt-4.1")._client.api_key)
    show("ConversationsSession", lambda: OpenAIConversationsSession()._openai_client)
    show("CompactionSession   ", lambda: OpenAIResponsesCompactionSession("s", SQLiteSession("s")).client)

-- SDK key only
model client        : sk-from-set-default-openai-key
ConversationsSession: OpenAIError - Missing credentials. Please pass a
CompactionSession   : OpenAIError - Missing credentials. Please pass a
-- OPENAI_API_KEY also set
model client        : sk-from-set-default-openai-key
ConversationsSession: sk-other-project-from-env
CompactionSession   : sk-other-project-from-env

Expected behavior

With no client passed and no default client set, both sessions use the key from set_default_openai_key(), as model calls do.

Root cause and a possible fix

The sessions fall back to AsyncOpenAI(): openai_conversations_session.py#L21, #L50 and openai_responses_compaction_session.py#L196. The provider passes get_default_openai_key() instead (openai_provider.py#L156-L161).

--- a/src/agents/memory/openai_conversations_session.py
+++ b/src/agents/memory/openai_conversations_session.py
-from agents.models._openai_shared import get_default_openai_client
+from agents.models._openai_shared import get_default_openai_client, get_default_openai_key
@@ async def start_openai_conversations_session(
-        _maybe_openai_client = default_client if default_client is not None else AsyncOpenAI()
+        _maybe_openai_client = (
+            default_client
+            if default_client is not None
+            else AsyncOpenAI(api_key=get_default_openai_key())
+        )
@@ class OpenAIConversationsSession(SessionABC):
-            _openai_client = default_client if default_client is not None else AsyncOpenAI()
+            _openai_client = (
+                default_client
+                if default_client is not None
+                else AsyncOpenAI(api_key=get_default_openai_key())
+            )
--- a/src/agents/memory/openai_responses_compaction_session.py
+++ b/src/agents/memory/openai_responses_compaction_session.py
-from ..models._openai_shared import get_default_openai_client
+from ..models._openai_shared import get_default_openai_client, get_default_openai_key
@@ def client(self) -> AsyncOpenAI:
-            self._client = default_client if default_client is not None else AsyncOpenAI()
+            self._client = (
+                default_client
+                if default_client is not None
+                else AsyncOpenAI(api_key=get_default_openai_key())
+            )

AsyncOpenAI(api_key=None) still falls back to OPENAI_API_KEY, so nothing changes for callers who haven't set a default key. With the patch, both sessions report the SDK key in both phases, and tests/memory passes (444 passed).