Part of duplicate code analysis: #aw_parent001main

Summary

Connection error handling and diagnostic logging is duplicated across launcher.go, log_helpers.go, and mcp/connection.go. Each file independently logs the command, args, env context, stderr output, and error-type hints using a similar log.Printf("[LAUNCHER] …") block structure. Divergence between these copies means diagnostics may be inconsistent or incomplete depending on which code path triggers the error.

Duplication Details

Pattern: Multi-step connection error diagnostics block

• Severity: Medium
• Occurrences: 3 distinct error-logging blocks across 3 files
• Locations:
  • internal/launcher/log_helpers.go — logLaunchError function (~lines 36–67)
  • internal/launcher/launcher.go — timeout branch and goroutine error branch (~lines 143–161)
  • internal/mcp/connection.go — NewConnection error handling (~lines 108–130)

log_helpers.go (logLaunchError):

logger.LogErrorWithServer(serverID, "backend", "Failed to launch MCP backend server%s: ...", ...)
log.Printf("[LAUNCHER] ❌ FAILED to launch server '%s'%s", serverID, sessionSuffix(sessionID))
log.Printf("[LAUNCHER] Error: %v", err)
log.Printf("[LAUNCHER] Debug Information:")
log.Printf("[LAUNCHER]   - Command: %s", serverCfg.Command)
log.Printf("[LAUNCHER]   - Args: %v", sanitize.SanitizeArgs(serverCfg.Args))
log.Printf("[LAUNCHER]   - Env vars: %v", sanitize.TruncateSecretMap(serverCfg.Env))
log.Printf("[LAUNCHER]   - Running in container: %v", l.runningInContainer)
// … hint analysis based on error message content

connection.go (NewConnection error path):

logger.LogErrorMd("backend", "MCP backend connection failed, command=%s, args=%v, error=%v", ...)
log.Printf("❌ MCP Connection Failed:")
log.Printf("   Command: %s", command)
log.Printf("   Args: %v", sanitize.SanitizeArgs(expandedArgs))
log.Printf("   Error: %v", err)
// stderr capture and printing
// executable-not-found hint
// EOF hint

Both blocks:

• Print command + args (sanitized)
• Print the error
• Analyze err.Error() for known strings ("executable file not found", "EOF", "no such file") and emit hints
• Log stderr if available

Impact Analysis

• Maintainability: Adding a new hint (e.g., for a new Docker error) must be done in both files; easy to miss one
• Bug Risk: Medium — diverged diagnostics mean some code paths give less helpful output to operators
• Code Bloat: ~30 lines × 2–3 occurrences = ~75 lines of largely duplicate diagnostic code

Refactoring Recommendations

1. Extract ConnectionErrorContext + LogConnectionError into a shared helper (e.g., internal/launcher/log_helpers.go already exists as a good home, or a new internal/mcp/errors.go):

   type ConnectionErrorContext struct {
       ServerID           string
       SessionID          string
       Command            string
       Args               []string
       Env                map[string]string
       RunningInContainer bool
       IsDirectCommand    bool
       StartupTimeout     time.Duration
       StderrOutput       string
   }
   
   func LogConnectionError(ctx ConnectionErrorContext, err error) {
       // Single place for structured + debug logging
       // Single place for error-string hint analysis
   }

2. Migrate all three sites to call LogConnectionError(...).

3. Estimated effort: ~3 hours to extract, migrate, and test.
   Benefits: single place to add/improve diagnostic hints; consistent output format for operators.

Implementation Checklist

• Review all three error-logging sites for full feature parity
• Design ConnectionErrorContext struct to capture all needed fields
• Implement LogConnectionError in a shared location
• Migrate log_helpers.go, launcher.go, and connection.go to use the helper
• Add unit tests verifying hint output for known error strings
• Run make test to verify no regressions

Parent Issue

See parent analysis report: #aw_parent001main

Generated by Duplicate Code Detector · ◷

• expires on Apr 1, 2026, 3:28 AM UTC