Class AppLogger

packages/node-runtime/src/logging/app-logger.ts:22–83

const MAX_SIZE_BYTES = 10 * 1024 * 1024 // 10MB

class AppLogger {
  private logFile: string
  private oldLogFile: string
  private threshold: LogLevel

  constructor(logsDir: string) {
    this.logFile = path.join(logsDir, 'app.log')
    this.oldLogFile = path.join(logsDir, 'app.old.log')
    this.threshold = resolveThreshold()
  }

  debug(scope: string, message: string, data?: unknown): void {
    this.write('DEBUG', scope, message, data)
  }

  info(scope: string, message: string, data?: unknown): void {
    this.write('INFO', scope, message, data)
  }

  warn(scope: string, message: string, data?: unknown): void {
    this.write('WARN', scope, message, data)
  }

  /** `data` may be an Error; its name/message/stack are extracted automatically. */
  error(scope: string, message: string, data?: unknown): void {
    this.write('ERROR', scope, message, data)
  }

  getLogPath(): string {
    return this.logFile
  }

  private write(level: LogLevel, scope: string, message: string, data?: unknown): void {
    if (LEVEL_ORDER[level] < LEVEL_ORDER[this.threshold]) return

    let line = `[${new Date().toISOString()}] [${level}] [${scope}] ${message}`

    try {
      const tail = formatData(data)
      if (tail) line += `\n${tail}`
      line += '\n'
      ensureDir(path.dirname(this.logFile))
      this.rotateIfNeeded()
      fs.appendFileSync(this.logFile, line, 'utf-8')
    } catch (err) {
      // Logging must never break the app; surface to console only.
      console.error('[AppLogger] Failed to write log:', err)
    }
  }

  // ponytail: rename-based rotation, atomic, no rewrite, ~20MB total ceiling
  private rotateIfNeeded(): void {
    let size = 0
    try {
      size = fs.statSync(this.logFile).size
    } catch {
      return // file doesn't exist yet
    }