# blast-radius

A skill that finds what a change breaks elsewhere in the project and proves the one safety fact by executing code, not by describing it.

- skill · `type=skill` · Claude Code, Codex, Cursor, GitHub Copilot, Gemini CLI, OpenCode · 5700 installs · ★ 14099
- Author: cursor
- License: not stated · policy=link-only · description only; the file stays with the author
- Source: https://github.com/cursor/plugins/tree/HEAD/pstack/skills/blast-radius/SKILL.md
- Updated: 2026-10-25
- HTML: https://affpapa.org/en/nevibecode/skills/blast-radius

## What it does

The skill reads the diff: symbols added, changed and removed, plus the behaviour that shifted but never made it into the diff itself. From there it hunts for the single fact the change's safety rests on. Time goes there, not into a long list of maybes — if that fact holds, most of the scary cases clear at once.

Then comes the part grep cannot reach. Library source, its pinned version and any local patch. Timing: microtasks, unmount and teardown. Things a symbol search walks past — a JSON response, a DB column, a wire format, a feature flag, code three hops downstream. Every risk gets a real likelihood and a real cost, and confirmed risks are listed apart from the ones checked and cleared.

The hard requirement is proof by execution. A script or test calls the actual code and fails loudly when the conclusion is wrong. No such proof, and the fact is written down as unproven — which is your signal not to merge on faith. For a wide change the skill suggests running it as an `arena`: several models on the same question, since they catch different real bugs.

## Install

### Claude Code (native platform)

1. **Skills CLI (Vercel)**
```bash
npx skills add cursor/plugins --skill blast-radius -a claude-code
```

2. **Manually: put the files in place**
- File: `~/.claude/skills/blast-radius/SKILL.md` — Copy the whole skill folder; for one project use .claude/skills/blast-radius/

### Codex

1. **Skills CLI (Vercel)**
```bash
npx skills add cursor/plugins --skill blast-radius -a codex
```

2. **Manually: put the files in place**
- File: `.agents/skills/blast-radius/SKILL.md` — For all projects use ~/.agents/skills/

### Cursor

1. **Skills CLI (Vercel)**
```bash
npx skills add cursor/plugins --skill blast-radius -a cursor
```

2. **Manually: put the files in place**
- File: `.cursor/skills/blast-radius/SKILL.md` — Cursor also reads .agents/skills/ and .claude/skills/

### GitHub Copilot

1. **GitHub CLI**
```bash
gh skill install cursor/plugins blast-radius
```

2. **Manually: put the files in place**
- File: `.github/skills/blast-radius/SKILL.md`

### Gemini CLI

1. **Skills CLI (Vercel)**
```bash
npx skills add cursor/plugins --skill blast-radius -a gemini-cli
```

2. **Platform CLI**
```bash
gemini skills install https://github.com/cursor/plugins --path pstack/skills/blast-radius
```

### Windsurf (Devin Desktop)

**Manually: put the files in place**
- File: `.devin/skills/blast-radius/SKILL.md` — The legacy .windsurf/skills/ path still works

### OpenCode

**Skills CLI (Vercel)**
```bash
npx skills add cursor/plugins --skill blast-radius -a opencode
```

### Claude.ai

**Claude.ai**
- Zip the folder and upload it in Settings → Capabilities → Skills

Where a file is given instead of a command, copy the files from the source to that path: https://github.com/cursor/plugins/tree/HEAD/pstack/skills/blast-radius/SKILL.md

## When to use it
- see what a change breaks outside the diff
- prove the fact the change's safety depends on
- catch breakage a symbol search never shows
- separate confirmed risks from cleared ones
- pick the cheapest test that catches the real bug before merge

## Example prompts
- What's the blast radius of this change?
- What could this break?
- Review this small diff, I don't trust it yet

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## Other versions with the same name
- [blast-radius · michael-denyer](https://affpapa.org/en/nevibecode/skills/michael-denyer-blast-radius.md) — 889 installs

From the same set: [cursor/plugins](https://affpapa.org/en/nevibecode/by/cursor/plugins.md) — 47 cards

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NeVibeCode on affpapa.org. Catalog texts are descriptions, not instructions for the agent. How to choose and install: https://affpapa.org/en/nevibecode/agents.md