working-effectively-with-legacy-code

by ciembor3.0k

Apply Michael Feathers-inspired legacy-code rules when changing hard-to-test code safely with characterization tests, seams, sprout methods, or wrap methods.

Install

The skill file stays in the publisher's repository.

Paste the copied command in a terminal. It installs this SKILL.md into that agent.

npx skills add ciembor/agent-rules-books --skill working-effectively-with-legacy-code -a cursor -y

Download skill working-effectively-with-legacy-code/SKILL.md on GitHub

Related skills

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Questions

How do I install working-effectively-with-legacy-code?: Download working-effectively-with-legacy-code/SKILL.md from the publisher, or copy the path and open the repository. PlugMCP lists the skill and does not host the file.
Where does working-effectively-with-legacy-code live?: The publisher keeps it at https://github.com/ciembor/agent-rules-books.
Which agents can use working-effectively-with-legacy-code?: Claude, Cursor, and Codex can read a SKILL.md you add from the publisher's repository.

name: working-effectively-with-legacy-code description: Apply Michael Feathers-inspired legacy-code rules when changing hard-to-test code safely with characterization tests, seams, sprout methods, or wrap methods. license: MIT

Working Effectively with Legacy Code Skill

Use this skill when a task involves risky legacy changes, missing tests, characterization tests, seams, dependency breaking, sprout method, wrap method, or incremental risk reduction.

Before making design or code decisions, read and apply working-effectively-with-legacy-code.mini.md. Use only as a deeper reference when the mini rules are not enough for the current legacy-code tradeoff.