[vishalhabib99]

Problem

pyproject.toml asks for mcp>=1.9.0, so a fresh pip install lightagent (0.11.0) now resolves mcp 2.3.0. mcp 2.x removed mcp.client.streamable_http.streamablehttp_client. In mcp_client_manager.py that import falls into the "older SDK" except ImportError branch, and every streamable-http server then fails with:

RuntimeError: installed MCP SDK does not support Streamable HTTP

The SDK supports it. It's newer, not older: 2.x has streamable_http_client(url, http_client=...). That function has no headers= argument, so headers have to travel on the httpx client.

Change

LightAgent/mcp_client_manager.py:

• Also import streamable_http_client and create_mcp_http_client. Both exist in mcp 1.24+ and 2.x.
• If the old streamablehttp_client exists, nothing changes. Otherwise, build the httpx client with create_mcp_http_client(headers=headers) (static headers plus the credential provider's), enter it on the same exit_stack so it closes with the session, and pass it to streamable_http_client.
• ClientSession(*streams[:2]) already handles both the 1.x three-stream and the 2.x two-stream shapes.

Tests

• New test test_streamable_http_works_on_mcp_2_without_streamablehttp_client uses the 2.x shape: the old name is missing, headers go through create_mcp_http_client, and the transport yields two streams. It fails on main and passes here.

• PYTHONPATH=. pytest -q tests: 366 passed, 1 skipped, in a venv from pip install -e ., which resolves mcp 2.3.0.

• End to end: a local streamable-HTTP MCP server whose tool echoes the X-Test request header, connected through MCPClientManager._create_session and then called:

  	mcp 1.25.0	mcp 2.3.0
  main	header=hello	RuntimeError: installed MCP SDK does not support Streamable HTTP
  this branch	header=hello	header=hello

Note: in a venv built from requirements.txt (mcp==1.10.1 and its pins), 33 test modules fail to import (cannot import name 'eval_type_backport' from 'pydantic._internal._typing_extra'), so I ran the suite from pyproject.toml instead.

[wxai-space]

The original contribution is preserved in follow-up PR #121. Real HTTP testing found an additional SDK 2.x tool-model difference (input_schema versus inputSchema), which is now handled for registration and calls. The follow-up also fixes the locked-SDK test failure, checks header precedence and cleanup/reconnect behavior, and adds a three-SDK compatibility CI matrix. Local stateless HTTP probes pass on MCP 1.12.4, 1.30.0, and 2.3.0; full suites pass on the locked and 2.3.0 SDKs. #121 is submitted for review only; no merge has been performed.

[vishalhabib99]

Thanks for carrying this forward in #121 and for catching the input_schema / inputSchema difference. I missed that one. Happy to test #121 against a real Streamable HTTP server if that would help.

[wxai-space]

The completed fixes have now been appended directly to this original contributor branch at c1852e3, preserving the existing commits and attribution. The newly triggered CI run passed all 7 checks: https://github.com/wanxingai/LightAgent/actions/runs/40616540724 . Supplemental PR #121 has been closed as redundant. This original PR remains open and unmerged for your review; main has not been modified.

[vishalhabib99]

Thanks @wxai-space, and for keeping the original commits. Catching the input_schema/inputSchema difference took real HTTP testing; I'd only exercised the connect path. The branch looks good to me as it stands.

[vishalhabib99]

Thanks for merging, @wxai-space, and for testing it against a real HTTP server. That's what caught the input_schema difference my PR missed.