logging

name	logging
description	Implement structured logging with log levels, formatting, and debugging. Use when adding logs to applications or debugging issues.

📋 Logging Skill

Log Levels

Level	When to Use
ERROR	Failures that need attention
WARN	Potential issues, degraded
INFO	Normal operations
DEBUG	Detailed debugging
TRACE	Very detailed (rarely)

---

JavaScript Logging

Console with Labels

const log = {
  error: (...args) => console.error('[ERROR]', new Date().toISOString(), ...args),
  warn: (...args) => console.warn('[WARN]', new Date().toISOString(), ...args),
  info: (...args) => console.log('[INFO]', new Date().toISOString(), ...args),
  debug: (...args) => console.debug('[DEBUG]', new Date().toISOString(), ...args)
};

// Usage
log.info('Upload started', { file: 'video.mp4', size: 1024 });
log.error('Upload failed', { error: err.message });

Structured Logger

class Logger {
  constructor(name, level = 'info') {
    this.name = name;
    this.levels = ['error', 'warn', 'info', 'debug'];
    this.minLevel = this.levels.indexOf(level);
  }

  _log(level, message, data = {}) {
    if (this.levels.indexOf(level) > this.minLevel) return;
    
    const entry = {
      timestamp: new Date().toISOString(),
      level: level.toUpperCase(),
      logger: this.name,
      message,
      ...data
    };
    
    console[level === 'error' ? 'error' : 'log'](JSON.stringify(entry));
  }

  error(msg, data) { this._log('error', msg, data); }
  warn(msg, data) { this._log('warn', msg, data); }
  info(msg, data) { this._log('info', msg, data); }
  debug(msg, data) { this._log('debug', msg, data); }
}

const logger = new Logger('uploader', 'debug');
logger.info('Processing file', { filename: 'video.mp4' });

---

Python Logging

import logging

# Setup
logging.basicConfig(
    level=logging.DEBUG,
    format='%(asctime)s [%(levelname)s] %(name)s: %(message)s'
)

logger = logging.getLogger('psi-engine')

# Usage
logger.info('Agent spawned', extra={'agent_id': 'agent_001'})
logger.error('Task failed', exc_info=True)  # Include stack trace

---

Chrome Extension Logging

// Filter Auto Accept logs
function log(msg, data = {}) {
  console.log(
    '%c[AA v30]%c ' + msg,
    'color: #10b981; font-weight: bold',
    'color: inherit',
    data
  );
}

// Remote logging (to server)
function remoteLog(level, message, data) {
  fetch('/api/logs', {
    method: 'POST',
    headers: { 'Content-Type': 'application/json' },
    body: JSON.stringify({ level, message, data, timestamp: Date.now() })
  }).catch(() => {}); // Silent fail
}

---

Best Practices

✅ Do	❌ Don't
Include context (ids, values)	Log sensitive data
Use appropriate level	Use console.log everywhere
Structure as JSON	Log entire objects
Add timestamps	Leave debug logs in prod
Log errors with stack	Ignore error logging

---

Debug Patterns

// Conditional debug
const DEBUG = process.env.DEBUG === 'true';
if (DEBUG) console.log('Detail:', data);

// Performance timing
console.time('upload');
await uploadFile(file);
console.timeEnd('upload');

// Group related logs
console.group('Upload Process');
console.log('File:', file.name);
console.log('Size:', file.size);
console.groupEnd();