Implements comprehensive logging of all RPC messages (requests/responses) sent and received by the gateway, with privacy preservation, server attribution, and payload previews.

Implementation

New RPC Logger (internal/logger/rpc_logger.go)

• Dual logging to text (mcp-gateway.log) and markdown (gateway.md) formats
• Privacy-preserving: reuses existing sanitizeSecrets() to filter tokens, API keys, passwords
• Payload preview: 10KB for text logs, 120 characters for markdown logs
• Metadata captured: direction (IN/OUT), server ID, method, payload size
• Concise format: Short, intuitive symbols and minimal verbosity for quick scanning

Integration Points

• internal/mcp/connection.go: New SendRequestWithServerID() method logs all backend communication
• internal/server/*.go: Updated callers to pass server ID for attribution

Log Format

Text (concise, scannable, up to 10KB payload):

github→tools/list 58b {"jsonrpc":"2.0"...}
github←resp 284b err:timeout {"result":{...}}

Markdown (inline, intuitive, up to 120 chars payload):

**github**→`tools/list` `{"jsonrpc":"2.0"...}`
**github**←resp ⚠️`timeout` `{"result":{...}}`

Format Features:

• Directional arrows: → (outbound), ← (inbound)
• Concise size notation: 58b
• Server attribution: **server**
• Inline payload preview: 10KB for text logs, 120 chars for markdown
• Error indicators: err:message (text), ⚠️ (markdown)

Testing

• 10 new unit tests covering truncation (10KB text, 120 chars markdown), sanitization, formatting, concurrency
• All existing tests pass (600+ unit, integration)

💡 You can make Copilot smarter by setting up custom instructions, customizing its development environment and configuring Model Context Protocol (MCP) servers. Learn more Copilot coding agent tips in the docs.