Python: Bug: MCPStreamableHttpPlugin.__aenter__() method doesn't treat HTTP 401/403 as fatal errors

[bararia-swati]

Describe the bug
The semantic_kernel MCPStreamableHttpPlugin.aenter() method has a bug - it doesn't treat HTTP 401/403 as fatal errors. It just logs them and keeps waiting.
I think the bug is in the _inner_connect() method of the semantic kernel mcp.py file you shared above.

Python
async def _inner_connect(self, ready_event: asyncio.Event) -> None:
try:
await session.initialize()
except Exception as ex:
await self._exit_stack.aclose()
raise KernelPluginInvalidConfigurationError(
"Failed to initialize session. Please check your configuration."
) from ex

The Bug:

1. connect() creates a background task running _inner_connect() and waits for ready_event
2. _inner_connect() calls session.initialize(), which makes the HTTP request to the MCP server
3. MCP server returns HTTP 401 Unauthorized
4. session.initialize() raises an exception
5. The exception handler in _inner_connect() raises KernelPluginInvalidConfigurationError
6. BUG: The exception handler does NOT call ready_event.set()
7. Meanwhile, connect() is still waiting at await ready_event.wait()
8. Since ready_event is never set, connect() hangs forever (until PromptFlow's 30-second timeout)
9. The exception is trapped in the background task and never propagates to our code

To Reproduce
Steps to reproduce the behavior:

1. Go to '...'
2. Click on '....'
3. Scroll down to '....'
4. See error

Expected behavior
A clear and concise description of what you expected to happen.

Screenshots
If applicable, add screenshots to help explain your problem.

Platform

• Language: [e.g. C#, Python]
• Source: [e.g. NuGet package version 0.1.0, pip package version 0.1.0, main branch of repository]
• AI model: [e.g. OpenAI:GPT-4o-mini(2024-07-18)]
• IDE: [e.g. Visual Studio, VS Code]
• OS: [e.g. Windows, Mac]

Additional context
Add any other context about the problem here.