Python: Add header_provider to Streamable HTTP MCP servers (#4849)

* Python: Add header_provider to MCPStreamableHTTPTool (#4808)

Add a header_provider callback parameter to MCPStreamableHTTPTool that
enables injecting dynamic per-request HTTP headers from runtime kwargs
(originating from FunctionInvocationContext.kwargs set in agent middleware).

The implementation uses contextvars and httpx event hooks to ensure headers
are task-local and safe for concurrent tool calls:

- header_provider receives the runtime kwargs dict and returns headers
- call_tool sets a ContextVar before delegating to MCPTool.call_tool
- An httpx request event hook reads from the ContextVar and injects headers

Example usage:
    mcp_tool = MCPStreamableHTTPTool(
        name="web-api",
        url="https://api.example.com/mcp",
        header_provider=lambda kwargs: {
            "X-Auth-Token": kwargs.get("auth_token", ""),
        },
    )

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* Address review feedback for #4808: Python: [Bug]: Unable to pass AgentContext to MCPStreamableHTTPTool

* Add test for header_provider via FunctionTool.invoke with FunctionInvocationContext

Addresses PR review comment: exercises the full pipeline from
FunctionInvocationContext.kwargs through FunctionTool.invoke to
MCPStreamableHTTPTool.call_tool and header_provider, rather than
testing call_tool in isolation.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* Address review feedback for #4808: review comment fixes

* Fix streamable MCP transport defaults

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* Fix Azure AI test client mocks

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* Fix MCP runtime kwarg regressions

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* Stabilize MCP tool runtime kwargs

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* Use context kwargs in MCP wrappers

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* updated mcp samples

* fix link

---------

Co-authored-by: Copilot <copilot@github.com>
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

python/packages/azure-ai/tests/test_azure_ai_client.py

@@ -77,7 +77,7 @@ def mock_project_client() -> MagicMock:
     mock_client.telemetry.get_application_insights_connection_string = AsyncMock()
 
     # Mock get_openai_client method
-    mock_client.get_openai_client = AsyncMock()
+    mock_client.get_openai_client = MagicMock()
 
     # Mock close method
     mock_client.close = AsyncMock()

python/packages/azure-ai/tests/test_provider.py

@@ -34,7 +34,7 @@ def mock_project_client() -> MagicMock:
     mock_client.telemetry.get_application_insights_connection_string = AsyncMock()
 
     # Mock get_openai_client method
-    mock_client.get_openai_client = AsyncMock()
+    mock_client.get_openai_client = MagicMock()
 
     # Mock close method
     mock_client.close = AsyncMock()