* feat: add Streamable HTTP transport support for remote MCP providers (#357)
Add `streamable_http` as a supported transport type for `MCPProvider`,
enabling connections to MCP servers that use the Streamable HTTP protocol
(e.g. Tavily remote endpoints). Previously only SSE transport was supported,
causing silent 5-minute timeouts when connecting to incompatible endpoints.
- Expand `MCPProvider.provider_type` to `Literal["sse", "streamable_http"]`
(default remains `"sse"` for backwards compatibility)
- Route `streamable_http` providers through `streamablehttp_client` from
the MCP SDK in `MCPIOService._get_or_create_session()`
- Handle variable-length context manager results from MCP transport clients
- Add `DataDesigner.list_mcp_tool_names()` for discovering available tools
- Update CLI form builder and controller to support the new transport option
- Add tests for streamable_http config, session creation, and form builder
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
* updates
* simplify import
* address greptile comments
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Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>
