refactor: Standardize error messages

[greynewell]

Problem

Error messages throughout the codebase are inconsistent. Some are user-friendly, others expose internal details that users don't need to see.

Examples

Good - User-friendly:

return asErrorResult('Directory argument is required and must be a string path');

Inconsistent - Internal details:

return asErrorResult(\`API call failed: \${error.message || String(error)}. Check server logs for details.\`);

Proposed Standards

1. User-facing errors should:

   • Be actionable (tell user what to fix)
   • Not expose internal stack traces
   • Use consistent format

2. Internal errors should:

   • Log full details to console
   • Return simplified message to user
   • Include error codes for debugging

Example Pattern

try {
  // operation
} catch (error) {
  console.error('[ERROR] Internal details:', error);
  return asErrorResult('Failed to process request. Please check your inputs.');
}

Files Affected

• src/tools/create-supermodel-graph.ts
• Query handlers in src/queries/
• Utility functions in src/utils/