Deprecation & migration
Retiring an old path safely: migrating consumers, proving nothing still calls it, then deleting it.
Installation
$ npx skills add addyosmani/agent-skillsThe CLI's unit is the repository, so this installs everything in addyosmani/agent-skills, not deprecation-and-migration alone. It writes into whichever agent directories it finds — Claude Code, Codex, Cursor, Copilot, Windsurf, Zed.
Summary
Retiring an old path safely: migrating consumers, proving nothing still calls it, then deleting it.
- Reach for it when the new implementation shipped six months ago and the old one is still there because nobody dared.
- Spans Review and Operate & maintain, so it is usually worth loading for the whole piece of work rather than at one moment in it.
- Stack-agnostic — nothing in it assumes a particular language or framework.
- Published by Addy Osmani. Well regarded, but not the vendor of the thing it covers.
- Installing pulls the whole addyosmani/agent-skills repository: this catalogue lists 19 other entries from it, and the repo may hold more.
Where it sits in delivery
ReviewReading a diff critically, and the far harder skill of acting on what a reviewer said.Everything in Review →
Operate & maintainProduction reality: debugging, performance, instrumentation, and writing down why the system is the way it is.Everything in Operate →
The skill itself
The full text lives with its publisher and changes when they change it. Read it there rather than here — a mirrored copy of somebody else's procedure goes stale silently, and this page would have no way of telling you.
Related
More in Review
- Analyzing .NET performanceTraces, dumps and allocation analysis, from the team that builds the runtime.
dotnet/skills - Vercel optimizeFinding and fixing what is slow or expensive in a Vercel-hosted app.
vercel-labs/agent-skills - Web performanceCloudflare's view of web performance — caching, edge behaviour and delivery.
cloudflare/skills - AccessibilityWCAG in practice — semantics, focus management, contrast, and what automated checks cannot see.
addyosmani/web-quality-skills - Core Web VitalsLCP, INP and CLS: what moves each one, and what only looks like it does.
addyosmani/web-quality-skills - Diagramming codeProduces accurate architecture and data-flow diagrams from the code that exists, not the code somebody described.
trailofbits/skills