Feat: streamable http

[pietrozullo]

Description

Implements streamable HTTP transport support in the TypeScript mcp-use library with automatic SSE fallback. The HttpConnector now intelligently tries streamable HTTP first and falls back to SSE for compatibility with older MCP servers.

Type of change

• New feature (non-breaking change which adds functionality)

Key Changes

1. HttpConnector Enhancement

• Now supports both streamable HTTP and SSE transports in a single connector
• Automatically tries streamable HTTP first, falls back to SSE on failure
• Properly detects 404/405 errors that indicate a server doesn't support streamable HTTP
• Tracks which transport type is actively being used

2. New Connection Manager

• Added StreamableHttpConnectionManager for managing streamable HTTP connections
• Follows the same pattern as existing SSE/WebSocket managers for consistency
• Provides access to session IDs when available

3. Transport Detection

• HttpConnector now exposes getTransportType() to check which transport is in use
• Improved error logging to clearly show fallback behavior
• Better error messages distinguish between transport-specific failures

4. Configuration Support

• Server configurations can use preferSse: true to force SSE transport
• Maintains backward compatibility with existing configurations
• No breaking changes to the API

5. Example Updates

• Updated http_example.ts to demonstrate the new transport capabilities
• Shows how to check which transport was selected
• Demonstrates both automatic and forced transport selection

Implementation Details

The implementation follows the Python mcp-use pattern:

1. Try streamable HTTP first - Better performance for modern servers
2. Fall back to SSE on any error - Maximum compatibility
3. Special handling for 404/405 - Clear indication that server doesn't support streamable HTTP
4. Transparent to users - Existing code continues to work without changes

Testing

The implementation has been tested with:

• Servers supporting only SSE (falls back correctly)
• Servers supporting streamable HTTP (uses it successfully)
• Servers supporting neither (appropriate error messages)
• Various error conditions (proper fallback behavior)

Checklist

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• The title of my pull request follows the conventional commits standard
• Changes have been documented in the README/documentation (if applicable)

Breaking Changes

None. This is a backward-compatible enhancement that improves performance for servers supporting streamable HTTP while maintaining full compatibility with SSE-only servers.