chore: import upstream snapshot with attribution

docs/sessions/sqlalchemy_session.md

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+# SQLAlchemy sessions
+
+`SQLAlchemySession` uses SQLAlchemy to provide a production-ready session implementation, allowing you to use any database supported by SQLAlchemy (PostgreSQL, MySQL, SQLite, etc.) for session storage.
+
+## Installation
+
+SQLAlchemy sessions require the `sqlalchemy` extra:
+
+```bash
+pip install openai-agents[sqlalchemy]
+```
+
+## Quick start
+
+### Using database URL
+
+The simplest way to get started:
+
+```python
+import asyncio
+from agents import Agent, Runner
+from agents.extensions.memory import SQLAlchemySession
+
+async def main():
+    agent = Agent("Assistant")
+    
+    # Create session using database URL
+    session = SQLAlchemySession.from_url(
+        "user-123",
+        url="sqlite+aiosqlite:///:memory:",
+        create_tables=True
+    )
+    
+    result = await Runner.run(agent, "Hello", session=session)
+    print(result.final_output)
+
+if __name__ == "__main__":
+    asyncio.run(main())
+```
+
+### Using existing engine
+
+For applications with existing SQLAlchemy engines:
+
+```python
+import asyncio
+from agents import Agent, Runner
+from agents.extensions.memory import SQLAlchemySession
+from sqlalchemy.ext.asyncio import create_async_engine
+
+async def main():
+    # Create your database engine
+    engine = create_async_engine("postgresql+asyncpg://user:pass@localhost/db")
+    
+    agent = Agent("Assistant")
+    session = SQLAlchemySession(
+        "user-456",
+        engine=engine,
+        create_tables=True
+    )
+    
+    result = await Runner.run(agent, "Hello", session=session)
+    print(result.final_output)
+    
+    # Clean up
+    await engine.dispose()
+
+if __name__ == "__main__":
+    asyncio.run(main())
+```
+
+
+## API reference
+
+- [`SQLAlchemySession`][agents.extensions.memory.sqlalchemy_session.SQLAlchemySession] - Main class
+- [`Session`][agents.memory.session.Session] - Base session protocol