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MCP Proxy Changelog

Track the evolution of the Plugged.in MCP Proxy server.

Latest Version

v1.10.6

Current Stable Release 100% MCP Protocol Compliance with enhanced testing

Version 1.10.x Series

[1.10.6] - 2025-02-09

Protocol Compliance

  • 100% MCP Specification Compliance: Fully compliant with MCP Spec
  • Protocol Version Validation: Added support for MCP protocol version negotiation (2024-11-05)
  • Header Standardization: Fixed all headers to use Title-Case format per spec (Mcp-Session-Id, Mcp-Protocol-Version)
  • CORS Enhancements: Added Access-Control-Expose-Headers to expose custom headers to JavaScript clients
  • Error Code Standardization: Implemented JSON-RPC 2.0 compliant error codes (-32600, -32601, -32603, -32001, -32000)

Code Quality

  • Extracted Constants: Created src/constants.ts for protocol constants, error codes, and port validation
  • Refactored Middleware: Extracted reusable middleware into src/middleware.ts for better maintainability
  • PORT Validation: Added comprehensive port validation (1-65535 range with fallback to 12006)
  • Transport Resolution: Simplified session/transport management with resolveTransport() helper

Testing

  • 84+ Tests Passing: Comprehensive test suite with 100% protocol compliance coverage
  • New Test Coverage: Added 8 new tests for:
    • CORS header validation (OPTIONS preflight for all endpoints)
    • Protocol version header casing (accepts any case, responds with Title-Case)
    • Session header casing (Title-Case response, accepts any request casing)
    • Authentication error handling (missing, malformed, incorrect tokens)
  • Zero Deprecation Warnings: Clean test output with no package deprecations

Documentation

  • Protocol Compliance Guide: New comprehensive documentation at /mcp-proxy/protocol-compliance
  • Smithery Deployment Guide: Moved detailed Smithery docs to docs/SMITHERY_DEPLOYMENT.md
  • Technical Specifications: Detailed protocol implementation, error codes, and architecture

Bug Fixes

  • Fixed DELETE request handling for missing session IDs (now returns 200 OK gracefully)
  • Fixed TypeScript type issues with optional parameters (stateless, requireApiAuth)

Performance

  • No performance regression - all middleware overhead < 1ms
  • Session lookup remains O(1) via Map
  • Stateless mode overhead: ~5ms per request

[1.10.2] - 2025-01-28

Fixed

  • Memory leak in connection pooling
  • OAuth token refresh race condition
  • STDIO server timeout handling

[1.10.1] - 2025-01-27

Fixed

  • Critical bug in tool name collision resolution
  • Connection cleanup on server disconnect

[1.10.0] - 2025-01-27

Added

  • OAuth Support: Full OAuth 2.0 flow for Streamable HTTP servers
  • Connection Pooling: Reuse connections for better performance
  • Health Monitoring: Automatic server health checks
  • Circuit Breaker: Prevent cascading failures

Changed

  • Improved error messages with actionable fixes
  • Enhanced retry logic with exponential backoff
  • Optimized memory usage by 40%

Security

  • Added rate limiting per API key
  • Enhanced input validation
  • Secure token storage for OAuth

Version 1.8.x Series

[1.8.0] - 2025-01-20

RAG v2 MCP Tools

Added new MCP tools for AI Document Exchange:
  • pluggedin_create_document - Create documents via AI
  • pluggedin_search_documents - Semantic document search
  • pluggedin_get_document - Retrieve documents
  • pluggedin_update_document - Update existing documents
  • pluggedin_list_documents - List all documents
  • pluggedin_delete_document - Remove documents

Performance

  • Optimized tool discovery caching
  • Reduced startup time by 50%
  • Improved response streaming

Version 1.4.x Series

[1.4.0] - 2024-12-15

Added

  • Streamable HTTP Transport: Full support for new transport type
  • Tool Prefixing: Automatic UUID prefixing to prevent collisions
  • Parallel Execution: Execute multiple tools simultaneously
  • Response Streaming: Stream large responses efficiently

Changed

  • Deprecated SSE transport in favor of Streamable HTTP
  • Improved error handling for network failures
  • Enhanced logging with structured output

Version 1.2.x Series

[1.2.6] - 2024-11-30

Fixed

  • STDIO server hanging on large outputs
  • Memory leak in SSE connections
  • Race condition in tool discovery

[1.2.0] - 2024-11-15

Added

  • Multi-Server Support: Aggregate multiple MCP servers
  • Authentication System: API key and custom auth support
  • Caching Layer: Cache tool discovery and resources
  • Metrics Endpoint: Prometheus-compatible metrics

Performance

  • 10x faster tool discovery with caching
  • Reduced memory footprint by 60%
  • Optimized for Docker deployment

Version 1.0.0

[1.0.0] - 2024-10-01

Features

  • Basic MCP proxy functionality
  • STDIO transport support
  • SSE transport support
  • Tool discovery and invocation
  • Resource listing
  • Prompt template support

Known Limitations

  • Single server support only
  • No authentication
  • Limited error handling
  • No connection pooling

Version 0.x Series (Beta)

[0.5.10] - 2024-09-15

Added

  • SSE transport experimental support
  • Basic error recovery
  • Debug logging

[0.5.9] - 2024-09-01

Added

  • Initial beta release
  • STDIO transport only
  • Basic tool invocation

Migration Guides

Migrating from 1.8.x to 1.10.x

1

Update Configuration

Add OAuth configuration for supported servers:
{
  "oauth": {
    "enabled": true,
    "provider": "github"
  }
}
2

Enable Health Checks

{
  "monitoring": {
    "health": {
      "enabled": true,
      "interval": 30000
    }
  }
}
3

Update Dependencies

npm update @pluggedin/mcp-proxy

Migrating from 1.2.x to 1.4.x

SSE transport is deprecated. Migrate to Streamable HTTP.
Update server configurations:
// Old (SSE)
{
  "transport": {
    "type": "sse",
    "url": "https://example.com/sse"
  }
}

// New (Streamable HTTP)
{
  "transport": {
    "type": "streamable",
    "baseUrl": "https://example.com/mcp"
  }
}

Deprecation Notices

SSE Transport

  • Deprecated in: v1.4.0
  • Removal planned: v2.0.0
  • Migration path: Use Streamable HTTP transport
  • Reason: SSE is not part of official MCP specification

Legacy Authentication

  • Deprecated in: v1.10.0
  • Removal planned: v2.0.0
  • Migration path: Use API key or OAuth
  • Reason: Security improvements

Performance Benchmarks

Tool Discovery Performance

VersionTime (ms)Memory (MB)
1.10.x4532
1.8.x12048
1.4.x25064
1.2.x50096
1.0.01200128

Connection Management

VersionMax ConnectionsPool Efficiency
1.10.x100095%
1.8.x50085%
1.4.x20070%
1.2.x10050%
1.0.010N/A

Roadmap

Version 2.0.0 (Q2 2025)

  • GraphQL API support
  • WebSocket transport
  • Plugin system
  • Distributed proxy clustering
  • Advanced caching strategies

Version 1.12.0 (Q1 2025)

  • WebAuthn authentication
  • Request/response transformation
  • Custom middleware support
  • Enhanced monitoring dashboard

Version 1.11.0 (Next Release)

  • Batch tool invocation
  • Response compression
  • Custom retry strategies
  • Enhanced OAuth providers

Breaking Changes Log

Version 1.10.0

  • Changed authentication header from X-API-Key to Authorization: Bearer
  • Removed deprecated servers.*.url in favor of servers.*.transport

Version 1.4.0

  • SSE transport moved to deprecated status
  • Changed tool discovery response format

Version 1.2.0

  • Configuration file format changed
  • API endpoints restructured

Support Policy

VersionStatusSupport Until
1.10.xActiveActive development
1.8.xMaintenanceJuly 2025
1.4.xSecurity onlyApril 2025
1.2.xEnd of Life-
1.0.0End of Life-

Reporting Issues

Found a bug or have a feature request?

Contributing

We welcome contributions! See our Contributing Guide for details.

License

MCP Proxy is released under the MIT License. See LICENSE for details.