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deep-debug-concurrency

Trace concurrency bugs through trigger-to-mutation workflows with read-only analysis.

6|Updated Mar 18, 2026
Search Tags:#debugging#postgresql#concurrency#webhooks#idempotency#race-condition
One-click install
npx skills add https://github.com/anotherben/claude-harness --skill deep-debug-concurrency
Or copy as Structured Prompt for Agent▼
Please help me install this Agent Skill.
Skill: deep-debug-concurrency
Source: https://github.com/anotherben/claude-harness/tree/main/skills/b-deep-debug-concurrency
Command: npx skills add https://github.com/anotherben/claude-harness --skill deep-debug-concurrency

SYSTEM DOCUMENTATION & REQUIREMENTS

What problem does it solve?

Deep root-cause analysis of concurrency, race condition, and duplicate processing bugs in large webhook-backed systems. It focuses on read-only investigation to identify where timing leads to duplicates or inconsistent processing, without changing any code.

Core Features & Use Cases

  • Read-only diagnostic framework to trace trigger → handler → idempotency check → mutation → side effects.
  • Phase-based approach for Shopify webhooks, background sync workers, and cron jobs to locate TOCTOU races and additive mutations.
  • Real-world scenarios include webhook double-firing, "processed twice" events, intermittent data corruption, and race-condition symptoms.

Quick Start

Follow a phase-based investigation to identify concurrency windows and idempotency gaps in your systems.

Frequently Asked Questions about deep-debug-concurrency

High-intent search queries and answers about installing and using this skill.

FAQPage Schema
What is a TOCTOU race condition in webhook processing?▼

A TOCTOU race condition occurs when a webhook handler checks a state and updates it later, allowing duplicate processing. This Skill traces the trigger to mutation path to identify these timing windows and idempotency gaps in high-concurrency backend systems.

Can I use this to find duplicate processing in PostgreSQL-backed cron jobs?▼

Trace intermittent data corruption in background sync workers by mapping the trigger to side effects pipeline. This approach enforces non-destructive, read-only analysis with SQL-based verification paths to locate additive mutations and concurrency bugs.

Can I use this to find duplicate processing in PostgreSQL-backed cron jobs?▼

Trace intermittent data corruption in background sync workers by mapping the trigger to side effects pipeline. This approach enforces non-destructive, read-only analysis with SQL-based verification paths to locate additive mutations and concurrency bugs.

What is the best way to investigate Shopify webhooks double-firing and processing twice?▼

Diagnose race conditions in webhook handlers using a read-only, phase-based investigation framework. It traces trigger to handler to idempotency checks and mutations to identify timing windows and duplicate processing safely without changing any code.

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