api-versioning-strategy

api-versioning-strategy is a skill for Claude Code, Codex from aj-geddes/useful-ai-prompts. It costs 48 tokens per session (918 once invoked), scanned A, original, MIT.

A guide to managing multiple versions of an API, the interface that software uses to communicate with other software. It covers URL or header versioning, compatibility, deprecation, and migration plans.

In plain words
What is it for?
Use it when designing a new API, adding incompatible changes, supporting several versions, routing versioned requests, or preparing migration documentation.
Why use it?
It helps you introduce breaking changes without unexpectedly disrupting existing clients. It also provides a way to retire old endpoints in an organized manner.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one.

Good fit Use it when designing a new API, adding incompatible changes, supporting several versions, routing versioned requests, or preparing migration documentation.

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Install with agentmods
npx agentmods add skills/aj-geddes/useful-ai-prompts/api-versioning-strategy
Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Any agent
npx skills add aj-geddes/useful-ai-prompts --skill api-versioning-strategy
Clone the repo
git clone --depth 1 https://github.com/aj-geddes/useful-ai-prompts

Made for: Claude Code, Codex.

Wrote this? Show the measurements

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README.md
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Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for api-versioning-strategy

Your own site · 80×15
<a href="https://agentmods.dev/skills/aj-geddes/useful-ai-prompts/api-versioning-strategy"><img src="https://agentmods.dev/badge/skills/aj-geddes/useful-ai-prompts/api-versioning-strategy.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 48 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 918 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe. Third-party audits
  • Socket pass 18 Mar 2026
  • Snyk pass 5 Mar 2026
How audits are shown
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00048 $0.00918
Opus 5 $0.00024 $0.00459
Sonnet 5 $0.00010 $0.00184
Haiku 4.5 $0.00005 $0.00092

Measured 12d ago against content hash 248c92d1d3c6, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-11, from the pricing page.

Security

Grade A, and why

api-versioning-strategy scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 12d ago.

The scan reads SKILL.md. This mod also ships 1 executable file (scripts/validate-api.sh), listed below but not scanned — reading those needs a real analyzer, not pattern matching.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

skills/api-versioning-strategy/SKILL.md · 117 lines

How it starts

The opening of the file, as written. The whole thing — 117 lines — stays where its author put it; the contents beside it link to each section on GitHub.

API Versioning Strategy

Table of Contents

Overview

Comprehensive guide to API versioning approaches, deprecation strategies, backward compatibility techniques, and migration planning for REST APIs, GraphQL, and gRPC services.

When to Use

  • Designing new APIs with versioning from the start
  • Adding breaking changes to existing APIs
  • Deprecating old API versions
  • Planning API migrations
  • Ensuring backward compatibility
  • Managing multiple API versions simultaneously
  • Creating API documentation for different versions
  • Implementing API version routing

Quick Start

Minimal working example:

// express-router.ts
import express from "express";

const app = express();

// Version 1
app.get("/api/v1/users", (req, res) => {
  res.json({
    users: [{ id: 1, name: "John Doe" }],
  });
});

// Version 2 - Added email field
app.get("/api/v2/users", (req, res) => {
  res.json({
    users: [{ id: 1, name: "John Doe", email: "[email protected]" }],
  });
});

// Shared logic with version-specific transformations
app.get("/api/:version/users/:id", async (req, res) => {
  const user = await userService.findById(req.params.id);

  if (req.params.version === "v1") {
    res.json({ id: user.id, name: user.name });
// ... (see reference guides for full implementation)

Reference Guides

Detailed implementations in the references/ directory:

Guide Contents
Versioning Approaches Versioning Approaches
Backward Compatibility Patterns Backward Compatibility Patterns
Deprecation Strategy Deprecation Strategy
Migration Guide Example Migration Guide Example
Response Structure Response Structure
Date Format Date Format, Error Format
JavaScript/TypeScript JavaScript/TypeScript, Python
GraphQL Versioning GraphQL Versioning
gRPC Versioning gRPC Versioning
Version Detection & Routing Version Detection & Routing
Testing Multiple Versions Testing Multiple Versions
Pattern 1: Version-Agnostic Core Pattern 1: Version-Agnostic Core, Pattern 2: Feature Flags for Gradual Rollout, Pattern 3: API Version Metrics

Read the full file on GitHub · 117 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 12d ago First seen · 117 lines · 48 tokens per session scan A 248c92d1d3c6

Subscribe to this mod's changes

api-versioning-strategy is a skill published in the GitHub repository aj-geddes/useful-ai-prompts (336 stars, last pushed 6mo ago), licensed MIT. It adds 48 tokens to every session and 918 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

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