Agent skill · software engineering · cursor
blast-radius
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.
Why this skill is useful
Provides a structured approach to validating code changes with real scripts and tests that the AI wouldn't reliably generate on its own.
What it needs
Requires git installed locally. About 3k tokens when loaded. Last updated 2026-08-06. 2,555 stars on the source repository.
What this skill does
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 1. Read the change. The diff, the symbols it adds, changes, and deletes, and what it now does differently, including the part the diff doesn't spell out. Use why step 2 to pull the PR and commits. 2. Find the one fact it's safe because of. Most changes that look risky are safe because of a single fact, like "this call only drops already-dead cache entries and does nothing else". Find that fact. If it holds, most risky cases are cleared at once. Spend your time here, not on a long list of maybes. 3. Look where grep stops. Read the source of the library you call, and check its pinned version and any local patch. …
How to use it
Reference it in AdaL, Claude Code, Cursor or any coding agent — nothing to install:
@skills cursor/blast-radius