🔖 Feature description

I propose implementing native asyncio support for the Python SDK using a Unified Client architecture. Instead of introducing a separate AsyncClient or a package.aio submodule (which stalled previous attempts like PR #453), asynchronous capabilities should be integrated directly into the existing Client and Service classes.

Core Implementation:

1. A single Client object handles both workflows.
2. Every service method is generated in a "Dual-Mode" pair directly alongside each other:
   • Synchronous: def list(self, ...):
   • Asynchronous: async def list_async(self, ...):
3. We transition the underlying HTTP engine from requests to httpx, which natively supports both synchronous and asynchronous operations using an identical API shape, making the dual-mode generator templates trivial to maintain.

🎤 Pitch

The community has requested native Python async support for over two years (Issue #26). Implementing a unified "Dual-Mode" pattern solves the architectural friction that halted previous PRs:

1. Maintainer Alignment: It addresses the exact feedback provided by core contributors in PR Async Support in Python SDK #453, who requested that async methods live alongside sync methods without requiring users to instantiate a whole new AsyncClient class.
2. Modern Developer Experience: Frameworks like FastAPI, Starlette, and Sanic are now standard. Developers must be able to await client.users.list_async() natively without blocking the event loop or hacking together ThreadPoolExecutors.
3. Zero Maintenance Drift: By utilizing Twig parameterDispatchBlock filters in the generator (similar to the new dual-mode C++ SDK), the synchronous and asynchronous methods are generated from the exact same spec source. They will never fall out of sync as the API evolves.
4. 100% Backwards Compatible: Existing code using requests semantics remains totally unaffected since standard def methods will work exactly as they did before.

👀 Have you spent some time to check if this issue has been raised before?

• I checked and didn't find similar issue

🏢 Have you read the Code of Conduct?

• I have read the Code of Conduct