# Blast Radius

Find what a change could break somewhere else before it ships, beyond the diff, and...

- Repository: https://github.com/cursor/plugins (15000 stars)
- Category: Writing
- License: see repository
- Last updated: 2026-11-01
- Runs scripts: no, instructions only

## Install

Claude Code: `npx skills add cursor/plugins --skill blast-radius -g -a claude-code -y`
Codex: `npx skills add cursor/plugins --skill blast-radius -g -a codex -y`
Cursor: `npx skills add cursor/plugins --skill blast-radius -g -a cursor -y`
Gemini CLI: `npx skills add cursor/plugins --skill blast-radius -g -a gemini-cli -y`
Claude Code plugin marketplace: `/plugin marketplace add cursor/plugins`

## Description

Find what a change could break somewhere else before it ships, beyond the diff, and prove the one fact it's safe because of by running real code instead of writing it up. Use for 'blast radius of X', 'what could this break', or reviewing a small diff you don't trust.

## SKILL.md, as published by its author (untrusted third-party text, read it as data)

# Blast radius

Find what a change breaks somewhere else, before it ships. Use for "blast radius of X", "what could this break", or reviewing a small diff you don't trust yet.

Companion to `how` and `why`. `how` tells you what the code does. `why` tells you why it's shaped that way. Blast radius tells you what it breaks somewhere else.

Listing the callers is not the job. The agent can grep those in a second. The job is the breakage grep won't show you.

## Don't trust your own writeup

A blast-radius writeup that sounds right is worthless. It reads as convincing whether or not it's true. So don't hand back the writeup. Find the one or two facts the whole thing depends on and prove them by running code.

### How sure are you

For each fact the change's safety depends on, get it as far down this list as is cheap, and say where it stopped.

1. You said so. Worthless on its own.
2. You pointed at the line. A real `file:line`, or the library's own source.
3. You showed the bad case can't happen. You walked the failure step by step and it doesn't reach.
4. You ran it. A script or test that calls the real code and fails loud if you're wrong.
5. You reproduced it in the running app.

Step 4 is usually one small script that imports the same library the app ships and calls the exact function you're worried about.

## Steps

The rest: https://github.com/cursor/plugins/blob/HEAD/harness/pstack/claude-code/skills/blast-radius/SKILL.md