feat(mcp): add transport security configuration for remote access

[Milofax]

Summary

This PR adds support for configuring transport security settings (allowed hosts and origins) when deploying the MCP server behind a reverse proxy like Nginx, Traefik, or Caddy.

Problem: The MCP server returns "Invalid Host header" (421) errors when accessed via a custom domain because the MCP SDK's DNS rebinding protection only allows localhost by default.

Solution: Make allowed_hosts, allowed_origins, and enable_dns_rebinding_protection configurable via config.yaml.

Changes

• Add transport security fields to ServerConfig schema (allowed_hosts, allowed_origins, enable_dns_rebinding_protection)
• Add build_transport_security() helper function that creates TransportSecuritySettings from config
• Integrate transport security configuration in server initialization via mcp.settings.transport_security
• Update MCP SDK requirement to >=1.23.0 (required for TransportSecuritySettings support)
• Add unit tests for transport security configuration
• Document transport security options in README.md
• Add commented example in config.yaml

Example Configuration

server:
  transport: http
  host: 0.0.0.0
  port: 8000
  
  # Transport security settings for remote access
  allowed_hosts:
    - "localhost:8000"
    - "graphiti.example.com"
  allowed_origins:
    - "http://localhost:3000"
    - "https://app.example.com"
  enable_dns_rebinding_protection: true  # Default: true

Test plan

• Unit tests added for build_transport_security() function
• Unit tests added for ServerConfig schema with new fields
• Unit tests added for environment variable overrides
• All existing tests pass (uv run python tests/test_configuration.py)
• Manual testing with reverse proxy (Traefik)

Related

• Addresses DNS rebinding protection (CVE-2025-66416)
• References: MCP SDK Issue #1798

🤖 Generated with Claude Code

[Milofax]

Friendly ping on this PR — adds transport security configuration for remote MCP access. Important for anyone running Graphiti MCP outside localhost. Happy to address any feedback!