A network timeout doesn't mean the request failed — it means the client doesn't know. So the client retries, and now the charge runs twice. Idempotency fixes this by making "do this operation" return the same result no matter how many times it's submitted under the same key. The trap: almost everyone implements it as "check if we've seen this key, if not do the work" — two non-atomic steps — which is precisely a race that two concurrent retries win together. This skill designs the key, the atomic dedup, the in-flight case, and the cleanup.
Idempotency Designer is a community-contributed Claude Code skill in the general-misc sub-category. It ships as a SKILL.md file that Claude Code auto-discovers under ~/.claude/skills/idempotency-designer/ and loads when your prompt matches the skill's trigger.
When to invoke it: Use when a POST/mutation can be retried (payments, order creation, sends, webhooks), or when duplicate side effects have already shown up in production.
The Idempotency Designer Claude Code skill is built for Claude Code users and developers across all disciplines looking for general-purpose AI assistance. It's part of ClaudSkills (also referred to as Claude Skills or Claude Code Skills) — the open community-curated registry of 196,000+ SKILL.md files for Anthropic's Claude Code agent and the wider Claude ecosystem (Claude API, Claude Agent SDK).
mkdir -p ~/.claude/skills/idempotency-designer curl -L https://claudskills.com/skills/idempotency-designer/SKILL.md \ -o ~/.claude/skills/idempotency-designer/SKILL.md
Or just download SKILL.md directly and drop it into ~/.claude/skills/idempotency-designer/. Claude Code auto-discovers it on next session.
Skills live at ~/.claude/skills/idempotency-designer/SKILL.md on macOS/Linux, or %USERPROFILE%\.claude\skills\idempotency-designer\SKILL.md on Windows. See the full install guide for step-by-step instructions.
Open @claudskills_bot on Telegram, tap Open Desktop App, and the desktop app installs this skill for you. Or share the bot link with a colleague — they get the same one-tap install. Learn more →
The ClaudSkills desktop app installs any skill directly into ~/.claude/skills/ with one click — no terminal required. Pro starts at $9/mo or $149 lifetime.
For the full experience including quality scoring and one-click install features for each skill — upgrade to Pro.
SKILL.md from the source repository to ~/.claude/skills/idempotency-designer/SKILL.md and restart Claude Code. Both flows are detailed at claudskills.com/install/.SKILL.md file that lives under ~/.claude/skills/<name>/ and tells the Claude Code CLI agent how to perform a specific task (instructions, prompts, allowed tools). Skills are auto-discovered at session start. Idempotency Designer is one of 67,000+ skills indexed in the open ClaudSkills catalog, classified under the General category. Learn more at /learn/what-is-a-claude-skill/.If you reference this skill in a blog post, paper, or documentation, you can cite it as:
@misc{idempotency-designer-2026,
author = {imtiazrayhan},
title = {Idempotency Designer [Claude Code skill]},
year = {2026},
publisher = {ClaudSkills},
url = {https://claudskills.com/skills/idempotency-designer/}
}Grade A · scanned 2026-09-28 — free static scan against the OWASP Agentic Skills Top 10.
No risk patterns were found in any of the ten OWASP-aligned categories. How grading works ›
Browse all General skills in the ClaudSkills registry, or explore these other picks from the same category:
Part of Acreator Store — Adam Lankamer's AI tools: PerfectStudio · Ucaption · UTagger · AutoXPoster · TestYourSkills · AutomationFlows · Au Naturel · Telegram @acreatorstore
SKILL.md files, not affiliated with, endorsed by, or sponsored by Anthropic.