What Could Break

Find what a change could break outside its own diff, then prove the one fact that makes it safe by running real code instead of writing an essay. Use before any multi-file edit or an edit to a shared path (API payload, config, stored data, a client other apps read, a prompt or policy file), when asked 'what could this break' or 'blast radius of X', for a small diff you do not trust, or when a task asserts something about existing code ('X already handles Y', 'just make X public') before you design against that assertion.

2 starsSoftware Development

Install

skills CLI (Claude Code, Cursor, Codex and more)

npx skills add stas4000/what-could-break --skill what-could-break

Manual install

git clone --depth 1 https://github.com/stas4000/what-could-break.git /tmp/what-could-break
mkdir -p ~/.claude/skills
cp -r /tmp/what-could-break/what-could-break ~/.claude/skills/what-could-break

Personal skills live in ~/.claude/skills. Use .claude/skills in a project folder to share a skill with your team.

From the SKILL.md

# What could break

Find what a change breaks somewhere else, before it ships. Run it before design,
not only before merge, whenever a task asserts something about existing code: that
assertion is a hypothesis, and the census of real consumers decides the design.

Listing callers is not the job. Grep does that in a second. The job is the breakage
grep will not show you, and one proof that the change is safe.

## Do not trust your own writeup

A risk analysis that sounds right is worthless. It reads as convincing whether or
not it is true. Find the one or two facts the whole change depends on and prove
them by running code.

For each such fact, get it as far down this ladder as is cheap, and say where it
stopped:

1. **You said so.** Worth nothing on its own.
2. **You pointed at it.** A real `file:line`, or the library's own source at the pinned version.
3. **You walked it.** You traced the bad case step by step and it does not reach.
4. **You ran it.** A script or test calls the real code and fails loud if you are wrong.
5. **You saw it live.** Reproduced in the running app, service or device.

Rung 4 is usually one small script that imports the same module production runs
and calls the exact function you are worried about, with the input you are worried
about.

## Steps

Read the full skill on GitHub

Details

Skill name: what-could-break
Repository: stas4000/what-could-break
Path: what-could-break/SKILL.md
License: MIT
Repo updated: 6 October 2026
Listed in: karanb192/awesome-claude-skills

FAQ

What does the What Could Break skill do?

How do I install the What Could Break skill?

skills CLI (Claude Code, Cursor, Codex and more): npx skills add stas4000/what-could-break --skill what-could-break. Skills go in ~/.claude/skills (personal) or .claude/skills (project), and Claude loads them automatically when a task matches the description.

Is What Could Break popular?

It lives in stas4000/what-could-break, which has 2 GitHub stars and 0 forks, and is included in 1 curated skill list.

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