observability

import { Registry, Histogram, Counter, collectDefaultMetrics } from 'prom-client';

export const register = new Registry();

collectDefaultMetrics({ register });

package middleware

import "net/http"

type StatusRecorder struct {
  http.ResponseWriter

class CheckoutService
  def initialize(cart:, user:)
    @cart = cart
    @user = user
  end

package observability

import (
  "expvar"
  "net/http"
)

Rails.application.config.filter_parameters += [
  :password,
  :password_confirmation,
  :secret,
  :token,
  :api_key,

package deps

import (
  "net/http"
  "time"

package admin

import (
  "net/http"
  "net/http/pprof"
)

module ApiRequestLogger
  extend ActiveSupport::Concern

  included do
    around_action :log_api_request
  end

export type CircuitState = "closed" | "open" | "half-open";

export interface CircuitBreakerOptions {
  failureThreshold: number;
  resetTimeout: number; // ms to wait in "open" before probing
  onStateChange?: (from: CircuitState, to: CircuitState) => void;

export type CheckResult = { name: string; status: 'up' | 'down'; durationMs: number; error?: string };
export type Check = () => Promise<void>;

function withTimeout(fn: Check, ms: number): Promise<void> {
  return new Promise((resolve, reject) => {
    const timer = setTimeout(() => reject(new Error(`timeout after ${ms}ms`)), ms);

// Structured logging with Winston (Node.js)
const winston = require('winston');
const { v4: uuidv4 } = require('uuid');

// Create logger
const logger = winston.createLogger({

import * as Sentry from "@sentry/react";

const environment = import.meta.env.VITE_ENVIRONMENT ?? "development";
const isProd = environment === "production";

export function initSentry(): void {