---
name: ciembor-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"
metadata:
  decimalai-skill-id: "7f321215-4141-403d-a655-4e76e086669c"
  decimalai-version-id: "a6d18079-b2d7-4f01-aaa5-c6da53a31ed2"
  decimalai-version: "1"
  decimalai-body-sha256: "aa81f1a2353ee8fc9be269a557a079a601de6785b44664672c22fe8cc0e38115"
  decimalai-name: "ciembor/working-effectively-with-legacy-code"
  decimalai-format: "1"
  decimalai-invocation: "model"
  decimalai-category: "coding"
  decimalai-source: "https://app.decimal.ai/s/ciembor-working-effectively-with-legacy-code@1/SKILL.md"
---
# 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](working-effectively-with-legacy-code.mini.md). Use [working-effectively-with-legacy-code.md](working-effectively-with-legacy-code.md) only as a deeper reference when the mini rules are not enough for the current legacy-code tradeoff.