Add debug logging for MCP skill startup time

[FL4TLiN3]

Background

initializeRuntime to skillConnected takes approximately 7 seconds, and we need to identify the bottleneck. Currently, StdioClientTransport is created with stderr: "ignore", so base skill startup logs are not captured.

Target File

packages/runtime/src/skill-manager/mcp.ts - McpSkillManager._initStdio() method

Proposed Changes

1. Add timing logs to measure each step

async _initStdio(skill: McpStdioSkill) {
  // ... env setup ...
  
  const startTime = Date.now()
  console.log(`[MCP] Starting skill ${skill.name}...`)
  
  const { command, args } = this._getCommandArgs(skill)
  const transport = new StdioClientTransport({ command, args, env, stderr: "pipe" })
  
  const transportStartTime = Date.now()
  await this._mcpClient.connect(transport)
  const connectTime = Date.now()
  
  console.log(`[MCP] Skill ${skill.name} connected in ${connectTime - transportStartTime}ms (total: ${connectTime - startTime}ms)`)
  
  // ... rest of the method ...
}

2. Change stderr from "ignore" to "pipe" and capture stderr output

const transport = new StdioClientTransport({ 
  command, 
  args, 
  env, 
  stderr: "pipe"  // Changed from "ignore"
})

// Capture stderr output
if (transport.stderr) {
  transport.stderr.on("data", (chunk: Buffer) => {
    console.log(`[MCP:${skill.name}:stderr] ${chunk.toString().trim()}`)
  })
}

Technical Considerations

• MCP SDK version: ^1.23.0
• Verify: Whether transport.stderr is a public API of StdioClientTransport
• Alternative: If transport.stderr is not accessible, consider other approaches to capture child process output

Expected Output

[MCP] Starting skill @perstack/base...
[MCP:@perstack/base:stderr] Running @repo/base-v1_0 version 1.0.0
[MCP] Skill @perstack/base connected in 150ms (total: 200ms)

Purpose

This change will help identify:

• Time from process spawn to log output (binary startup time)
• connect() duration (MCP handshake time)
• Total elapsed time

Notes

• This is for debugging purposes
• Consider adding a debug flag to enable/disable verbose logging in production