Home / sigistry / marketplace · GitHub

idempotency-patterns SKILL.md skillA

idempotency-patterns from sigistry/marketplace is an agent skill: a SKILL.md folder an AI agent loads when a task calls for it.

Install it, pinned

mdr add sigistry/marketplace/idempotency-patterns@git:20260826.571bc2f

Pins git:20260826.571bc2f in mdr.lock. Pin the fingerprint instead.

Audit grade: A, 17 of 17 checks passed
Kind: SKILL.md skill
Repository: sigistry/marketplace
Path: plugins/api-contract-keeper/skills/idempotency-patterns/SKILL.md
Versions recorded: 2
Latest version: git:20260826.571bc2f, committed Aug 26, 2026
First version recorded: Jul 15, 2026
Size: 4,669 bytes
Repository stars: 3
License: MIT

This skill should be used when the user mentions "idempotency", "idempotency key", "retries", "exactly once", "double charge", "pagination", "cursor", "offset", "rate limit", "rate limiting", "Retry-After", "safe retries", or making an unsafe HTTP method safe to retry. It provides idempotency-key store recipes, safe-retry semantics for POST/PATCH/DELETE, and cursor/offset pagination plus standard rate-limit headers.

Collected from public GitHub. Every version is saved exactly as it was and never changes. Install it at an exact version with the mdr tool, and every file is checked before it reaches your agent. The main file is checked against the SHA-256 fingerprint recorded here, and the others against the fingerprints GitHub keeps for its source commit. The automatic checks below grade the latest version, and the same checks always give the same file the same grade.

What the file says

# Idempotency Patterns

## Purpose
Provide standardized recipes for the three pieces of API plumbing that clients depend on and servers get subtly wrong: **safe retries** (idempotency keys so a retried mutation applies once), **pagination** (stable, bounded traversal of collections), and **rate limiting** (standard headers so clients back off correctly). All three are static, framework-agnostic patterns, apply them at the boundary, in the handler.

## Why idempotency
HTTP defines `GET`, `HEAD`, `PUT`, and `DELETE` as **idempotent** (repeating them has the same effect as doing them once) and `GET`/`HEAD` as **safe** (no side effects). `POST` is **neither**: and networks retry. A client that times out and retries a `POST /payments` can charge twice. The fix is an **idempotency key**: the client sends a unique `Idempotency-Key` header; the server records key → outcome and, on replay, returns the stored outcome instead of re-executing.

### The idempotency-key algorithm (unsafe methods only)
1. Read the `Idempotency-Key` header. If absent on a create endpoint, either require it (`400`) or proceed without dedup, decide per endpoint.
…

Read the whole file at its exact version.

How to install

The exact contents, by fingerprint

mdr add sigistry/marketplace/idempotency-patterns@sha256:c6146589075f9a1f

The line at the top of this page pins the label git:20260826.571bc2f, which is what most people want. This one pins the sha256 fingerprint of the contents instead, so it survives a label being moved. Either way the exact version is written to mdr.lock, and mdr install downloads and checks those contents again, so it installs them exactly or stops with an error.

Badge

[![mdr](https://markdownregistry.com/badge/art_tr26ltwjf7tmr2x2.svg)](https://markdownregistry.com/a/art_tr26ltwjf7tmr2x2)

4 badge image fetches in 30 days. What the badge shows.

Versions

The registry has recorded 2 versions of this file, between Jul 15, 2026 and Aug 26, 2026, about one every 42 days.

version	committed	commit	size	audit
git:20260826.571bc2f latest	2026-08-26	571bc2f	4,669 B	A	view · diff
git:20260715.6169119	2026-07-15	6169119	4,669 B	A	view

Audit of the latest version

A 17 of 17 checks passed. Fixed automatic checks with no AI involved, so the same checks give the same answer every run.

pass: Frontmatter block present
pass: Frontmatter declares a name
pass: Frontmatter declares a description
pass: Size between 200 bytes and 200 KB (4669 bytes)
pass: No zero-width or bidi control characters
pass: No instruction hidden inside an HTML comment
pass: No link to an exfiltration or paste host
pass: No credential-shaped string
pass: No instruction to send local credentials anywhere
pass: No text hidden with inline styles
pass: No prompt-injection phrasing
pass: No curl or wget piped into a shell
pass: No recursive delete of root, home or parent
pass: No instruction to read or print local credentials
pass: No base64 blob over 200 characters
pass: No link to a raw IP address
pass: No script tag

Source

GitHub

sigistry/marketplace · 3 stars · license MIT · pushed 2026-10-30 · branch main

API

GET https://markdownregistry.com/api/v1/artifacts/art_tr26ltwjf7tmr2x2
GET https://markdownregistry.com/api/v1/resolve?ref=sigistry/marketplace/idempotency-patterns
GET https://markdownregistry.com/api/v1/blob/c6146589075f9a1f0828ad74a8a97d876d99804bff06b51cb66636d544d2ba5c

Your AI assistant does the legwork. You hear about the deals worth your word. Hand yours the standing instructions at modelranch.com and it joins the network that reads files like this one.

Guides: the SKILL.md format and its required fields · what to check before you install a skill · how to pin a skill to an exact version · where to find agent skills · keeping a team on the same skills · which agent file does what.

More from sigistry/marketplace

catalog-hygiene SKILL.md skill

sigistry/marketplace · plugins/a11y-i18n-remediator/skills/catalog-hygiene/SKILL.md · This skill should be used when the user mentions "translation catalog", "i18n keys", "missing translations", "unused…