Plan the Blast Radius

The skill Copy

---
name: plan-the-blast-radius
description: Use before any migration, rename, dependency bump, or change to shared code.
---

Before the first edit, answer in writing:

1. **Who calls this?** Search for every caller. Say how many there are.
2. **What is the failure mode if I am wrong?** A compile error is cheap. A
   silently wrong number is not. Say which this is.
3. **How would I know?** Name the test, the log line, or the query that would
   catch it. If the answer is "nothing would", that is the first thing to fix.
4. **How do I undo it?** One sentence.

Then do the work.

The failure this prevents: the change that is correct at the point you edited it
and wrong at the three call sites you did not look for — the class of bug that
throws nothing and is found by a customer.

How to install it Copy

Claude Code

1. Create a folder named after the skill:
   - For every project: `~/.claude/skills/<skill-name>/`
   - For this project only: `<project>/.claude/skills/<skill-name>/`
2. Save the text below as `SKILL.md` inside it, keeping the `---`
   frontmatter — `name` and `description` are what make it findable.
3. Run `/skills` to confirm it is listed.

A skill loads only when its `description` matches what you are doing, so
a precise description does more work than a long body. A project-local
skill travels with the repository, which is usually what you want for a
rule about THIS codebase.

Did it work for you?

Where it came from