PRODUCTION RESCUE LOGS // 03 REAL CASE STUDIES

Real Rescue Logs: Code Surgery & Bug Hunt Case Studies

Real engineering teardowns of broken AI codebases, cloud bill spikes, and race condition bugs we salvaged. Click any case study below to read full line-by-line postmortems.

CLOUD INFRASTRUCTURE & BACKEND SHIELD•LOG #01

The $18,000 Cloud Bill API Bug: Halting an Infinite Recursion Loop

SAVED $18,400 / AWS & SUPABASE

How a silent infinite recursion loop in an AI-generated serverless function spawned 4.2 million un-cached database queries in 72 hours, triggering an unexpected $18,400 bill spike on AWS & Supabase.

Unused Queries Blocked4.2M / day
Cloud Bill Reduction-$18,400
API Response Speed99.4% Faster
ENGINEERING RECOVERY STEPS EXECUTED:
Eliminated Un-cached Serverless Database Polling Loops
Implemented Redis Query Caching & Edge Rate Limiting
Configured AWS Cost Anomaly Guards & Hard Limits
Stabilized Database Connection Pool under Heavy Traffic
Read Line-by-Line Code Postmortem & FixRead Full Case Study
CONCURRENCY & RACE CONDITION QA•LOG #02

The Ghost Inventory Bug: How a Race Condition Double-Booked 120 Users

0 DOUBLE-BOOKINGS / 5,000 CONCURRENT USERS

An engineering teardown of how non-atomic Read-then-Write database logic allowed two concurrent users to claim the exact same seat within a 5-millisecond window while returning 200 OK.

Double-Bookings120 ➔ 0
Refund Penalties Saved$18,400
Stress-Test Load5,000 VUs
ENGINEERING RECOVERY STEPS EXECUTED:
Replaced Non-Atomic Reads with SELECT FOR UPDATE Row Locks
Implemented Redis Distributed Mutex Locks on Booking Gate
Prevented Double-Charge Credit Card Chargebacks
Passed 5,000 Virtual User Concurrency Stress Test
Read Line-by-Line Code Postmortem & FixRead Full Case Study
AI CODE SURGERY & REFACTORING•LOG #03

Rescuing an AI-Built MVP (Cursor & v0) from 14,000 Lines of Spaghetti Code

4 MONTHS STUCK ➔ LAUNCHED IN 3 WEEKS

How we rescued a solo founder’s SaaS product built entirely with AI tools that was crashing for 4 out of 10 users, refactored the monolith, and scaled it to 25,000 users.

Launch Timeline3 Weeks
Crash Rate Drop-89%
Traffic Scale Capacity50x (25k Users)
ENGINEERING RECOVERY STEPS EXECUTED:
Refactored 14,000 Lines of Un-modularized Monolithic JSX
Isolated Global State Mutation & Fixed Memory Leaks
Restructured Database Queries for High-Traffic Scale
Shipped Production MVP to Real Paying Customers
Read Line-by-Line Code Postmortem & FixRead Full Case Study
FACING SIMILAR PRODUCTION BUGS?

Get a Deep Bug Hunting & Concurrency Audit

Book a 10-minute engineering triage call. Our senior leads trace silent memory leaks, payment webhook drops, and API security vulnerabilities under strict NDA.