deprecation-and-migration

An agent skill by addyosmani, from addyosmani/agent-skills. Tags: api, debugging, developer-tools, documents.

What it does

Manages deprecation and migration. Use when removing old systems, APIs, or features. Use when migrating users from one implementation to another. Use when migrating a database schema in production, such as renaming or dropping a column without downtime (expand/contract). Use when deciding whether to maintain or sunset existing code.

Install

With the skills CLI, which installs into Claude Code, Codex, Cursor and other agents:

npx skills add addyosmani/agent-skills --skill deprecation-and-migration

Or copy the skill folder into Claude Code's skills directory by hand (~/.claude/skills for every project, or .claude/skills inside one):

git clone --depth 1 https://github.com/addyosmani/agent-skills
cp -r agent-skills/skills/deprecation-and-migration ~/.claude/skills/deprecation-and-migration

Safety box score

Grade B, low risk: 18 of 100 risk points, rated 2026-10-21. The grade rates what the skill and its scripts can reach on the machine of whoever installs it, across eight categories from shell execution to secrets access. How the score works.

This skill is documentation-only guidance for deprecating systems and performing expand/contract migrations. It does not ship executable code, but it does include an example `npx` verification command and it explicitly guides destructive removal of code and database columns after migration checks.

Category levels, from 0 (none) to 3 (high)
Category	Level	Why
Code & shell execution	1 (low)	The only executable action shown is the example command `npx migrate-check`, so direct execution exposure is low.
Network access	1 (low)	That `npx` example may fetch a package from the registry at runtime; no other outbound network flow is described.
Filesystem reach	1 (low)	The final removal steps say to "Remove the code" and "Remove associated tests, documentation, and configuration," which is broad but stays inside the project.
Secrets & credentials	0 (none)	No tokens, passwords, key stores, `.env` files, or other credential sources are mentioned.
Privilege & persistence	0 (none)	There is no sudo, global install, service registration, shell startup edit, or OS-setting change in the file.
Instruction hijack surface	0 (none)	The skill contains no prompt-injection text, hidden instructions, or requests to ignore higher-priority rules.
Irreversible actions	2 (moderate)	Its core purpose includes removing old systems and later dropping database columns; that destructive migration capability is inherent to the skill's purpose, even though it is gated by verification.
Transparency	0 (none)	All provided material is readable markdown; there are no binaries, installers, or decoded blobs.

Before installing

Review whether you are comfortable with the agent removing code and dropping schema after migration checks.
Vet or pin the `migrate-check` package before allowing `npx migrate-check` to run.
Try the expand/backfill/contract flow on a nonproduction copy first.

Rated 2026-10-21 by an automated review of 1 file from the skill's repository.

Source

Repository: addyosmani/agent-skills (all skills from this repository)
Path: skills/deprecation-and-migration/SKILL.md
Branch: main
Updated: 2026-09-19

intended-vs-implemented — The method for finding the gap between what a system is supposed to do and what the code actually does — the class of bug generic scanners miss because they.
code-review-and-quality — Conducts multi-axis code review. Use before merging any change. Use when reviewing code written by yourself, another agent, or a human.
constraint-driven-development — Establishes a project's quality bar as a written contract and stops agents quietly lowering it.
debugging-and-error-recovery — Guides systematic root-cause debugging.
documentation-and-adrs — Records decisions and documentation.
doubt-driven-development — Subjects every non-trivial decision to a fresh-context adversarial review before it stands.