[language-support] Serena MCP Language Support Cannot Be Tested Through HTTP Gateway

[github-actions]

Problem

The Language Support Tester workflow cannot test Go, TypeScript/JavaScript, and Python language support using the Serena MCP server because of a fundamental incompatibility between Serena's session requirements and the HTTP gateway architecture.

Root Cause

Serena MCP Server is a stdio-based MCP server that requires:

• Persistent, streaming connections where initialization and tool calls happen on the same connection
• Session state maintained throughout the connection lifecycle
• The initialization handshake must be completed before tool calls can be made

The HTTP Gateway provides:

• Stateless HTTP requests where each request is independent
• No persistent connection to maintain session state
• Each HTTP POST is treated as a separate session by Serena

Error Observed

When attempting to call Serena tools through the HTTP gateway:

{
  "jsonrpc": "2.0",
  "id": 2,
  "error": {
    "code": 0,
    "message": "method \"tools/list\" is invalid during session initialization"
  }
}

This occurs because:

1. The initialize request completes successfully in one HTTP request
2. Subsequent tools/call requests are sent as separate HTTP requests
3. Serena treats each new HTTP request as a new session that hasn't completed initialization

Impact

Language support testing is blocked for:

• ❌ Go language analysis (symbol finding, definitions, refactoring)
• ❌ TypeScript/JavaScript language analysis
• ❌ Python language analysis

Documentation

This limitation is documented in:

• test/serena-mcp-tests/GATEWAY_TEST_FINDINGS.md - Comprehensive analysis of the behavioral differences
• test/serena-mcp-tests/README.md - Test suite documentation mentioning stdio vs HTTP differences

Current Workarounds

The existing test scripts work correctly:

• ✅ test/serena-mcp-tests/test_serena.sh - Direct stdio connection tests (15/23 tests pass)
• ❌ test/serena-mcp-tests/test_serena_via_gateway.sh - Gateway tests (7/23 tests pass due to this issue)

Possible Solutions

Option 1: Enhance Gateway with Session Persistence

Modify the gateway to:

• Maintain persistent stdio connections to backend servers
• Map multiple HTTP requests from the same session (via Authorization header) to the same backend connection
• Keep the backend connection alive across multiple HTTP requests

Option 2: Use HTTP-Native Serena

• Develop or deploy an HTTP-native version of Serena that doesn't require streaming connections
• HTTP-native servers are designed for stateless HTTP requests

Option 3: Update Workflow to Use Direct stdio

• Modify the Language Support Tester workflow to connect directly to Serena via stdio instead of through the HTTP gateway
• This would bypass the gateway limitation but may not match the production architecture

Recommendation

Option 1 (Gateway Enhancement) is recommended because:

• It maintains the gateway architecture
• It allows stdio-based MCP servers to work through HTTP proxying
• It doesn't require changes to existing MCP servers like Serena
• It would benefit other stdio-based MCP servers

References

• MCP Protocol: https://github.com/modelcontextprotocol
• Gateway Config: config.toml (Serena server on line 22-27)
• Test Findings: test/serena-mcp-tests/GATEWAY_TEST_FINDINGS.md

Generated by Language Support Tester

• expires on Feb 24, 2026, 2:08 PM UTC