@molecule/api-logger-winston

Auto-generated, AI-first package reference for the molecule.dev ecosystem. It is written to be read by coding agents as much as by people, and is generated from this package's source — edit src/index.ts JSDoc, not this file.

Winston logger provider for molecule.dev.

Provides a full-featured logger implementation using winston.

Quick Start

import { logger, setLogger } from '@molecule/api-logger'
import { createLogger, provider } from '@molecule/api-logger-winston'

// Default: colorized console output
setLogger(provider)
logger.info('Server started on port', 3000)
logger.error('Database connection failed', error) // message + full stack

// Custom instance: JSON to a file — level omitted, so this instance defers
// to the core's LOG_LEVEL/setLevel() gate
setLogger(
  createLogger({
    format: 'json',
    transports: [{ type: 'file', options: { filename: 'app.log' } }],
  }),
)

Type

provider

Installation

npm install @molecule/api-logger-winston @molecule/api-logger winston

API

Interfaces

Logger

Logger interface that all implementations must satisfy.

interface Logger {
  trace(...args: unknown[]): void
  debug(...args: unknown[]): void
  info(...args: unknown[]): void
  warn(...args: unknown[]): void
  error(...args: unknown[]): void
}

WinstonLoggerOptions

Options for creating a winston logger.

interface WinstonLoggerOptions {
  /**
   * Minimum level for the winston instance. Defaults to `'trace'`
   * (pass-through, via winston's `'silly'` level) — minimum-level filtering
   * is meant to happen once, in `@molecule/api-logger`'s gate (`LOG_LEVEL` /
   * `setLevel()`). Pass an explicit `level` only to add a second, stricter
   * gate on this instance specifically. `'silent'` is implemented via
   * winston's `silent: true` flag (winston has no built-in `'silent'` level).
   */
  level?: LogLevel
  /** Output format. Defaults to `'json'` (timestamps + error stacks); `'console'` is colorized. */
  format?: 'json' | 'console'
  /** Transports to attach. Defaults to a single console transport. */
  transports?: WinstonTransportConfig[]
}

WinstonTransportConfig

Configuration for a winston transport.

stream expects a writable stream in options.stream — useful for tests and in-process sinks. Unknown types fall back to a console transport.

interface WinstonTransportConfig {
  type: 'console' | 'file' | 'http' | 'stream' | string
  /** Per-transport level override. Omitted = inherit the parent logger's level (NOT pass-through). */
  level?: LogLevel
  options?: Record<string, unknown>
}

Types

LogLevel

Log levels supported by the logger.

type LogLevel = 'trace' | 'debug' | 'info' | 'warn' | 'error' | 'silent'

Functions

createLogger(options)

Creates a winston-based logger that implements the Logger interface. Supports console, file, HTTP, and stream transports.

function createLogger(options?: WinstonLoggerOptions): Logger

• options — Winston configuration (log level, format, transports).

Returns: A Logger backed by winston.

Constants

format

Winston format utilities for convenience.

const format: typeof winston.format

provider

The default winston logger with console format.

Level filtering is delegated to @molecule/api-logger's gate (LOG_LEVEL / setLevel(), default 'info') — the underlying instance passes everything through so the core's single gate governs; a second gate here would make the core's setLevel('debug') silently no-op.

const provider: Logger

transports

Winston transports for convenience.

const transports: winston.transports.Transports

Namespaces

winston

Core Interface

Implements @molecule/api-logger interface.

Bond Wiring

Setup function to register this provider with the core interface:

import { setLogger } from '@molecule/api-logger'
import { provider } from '@molecule/api-logger-winston'

export function setupLoggerWinston(): void {
  setLogger(provider)
}

Injection Notes

Requirements

Peer dependencies:

• @molecule/api-logger ^1.0.1

Runtime Dependencies

• @molecule/api-logger

• winston

• Console-style variadic calls are bridged onto winston's (message, meta) shape: logger.info('msg', contextObj) merges contextObj into the record, and an Error (alone or after a message) keeps its stack. Naively stringifying args would print [object Object] and drop stacks.

• Both the default provider AND createLogger() (level omitted) pass every level through to winston — minimum-level filtering happens once, in @molecule/api-logger (LOG_LEVEL / setLevel(), default 'info'). Passing an explicit level to createLogger() adds a SECOND, bond-side gate below the core's; a stricter level there makes the core's setLevel('debug') appear to do nothing — only do this if you actually want a second, independent filter on this specific instance.

• level: 'silent' is implemented via winston's silent: true flag (there is no built-in winston 'silent' level) — it drops output unconditionally, regardless of the configured level.

• Transport types: console, file, http, and stream (options.stream = any writable — handy for tests and in-process sinks). A transport's own level follows the same rules as createLogger's top-level level; omitted, it inherits the parent instance's level instead of defaulting to anything.