agentleFS
Sign inStart free
fullerzzfullerzz/agent-skills/skills/blast-radius/SKILL.md

blast-radius

Skill2 starsChanged 29 days agoMITView on GitHub

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.

We split this skill into the rules it gives an agent

2 rules. 0 are common, 0 are distinctive, and 2 are very specific to this project.

  • 0

    Common

    Most of the 87 edited versions we read keep these.

  • 0

    Distinctive

    This author's own choices. Worth a look.

  • 2

    Very specific

    Tied to their project's names, files or tools. Probably skip.

  • Common
  • Distinctive
  • Very specific
  1. Very specific:

    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 …

    line 33
  2. Very specific:

    Write it through unslop, cite real code, and strip anything private before it goes anywhere public.

    line 48

“Common” is measured: kept by at least 6 in 10 of the 87 edited versions of this file we could read. “Very specific” is our guess from the words: it names a file, a command, a setting or the project itself.

Keep what fits and drop the rest. Your version, ready for your agents.
Files
SKILL.md

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. Work out when things run: microtasks, unmount and teardown, Solid versus React. Follow what a symbol search misses: the JSON an API returns, a DB column, a wire format, another language reading the same bytes, a feature flag, code three hops downstream.
  4. Be honest about each risk. Give it a real chance of happening and a real cost if it does. Keep the risks you confirmed. List the ones you checked and cleared separately. Same rules as why. Cite a real file:line, a search that finds nothing is still an answer, and never make up a caller or an API.
  5. Prove the one fact. Run an existing relevant check, or when permitted write a small check against real code and run it. A read-only request must not create files; report missing execution permissions as a gap.
  6. For a big or wide change, run it as an arena. Use independent native read-only reviewers under the native contract, then verify and merge their findings. Report actual identities and gaps without claiming provider diversity.

What to hand back

  • What it does. What changed, including the part that isn't obvious.
  • The one fact it's safe because of. State it, say which step you got it to, and show the proof. If you couldn't prove it, write unproven.
  • Risks. Each names how it breaks, the file:line, how likely and how bad, and how to check. Paste the proof for the ones that matter.
  • Cleared. What you checked and why it's fine.
  • Before you merge. The cheapest test or repro that catches the real bug, including the script you wrote.

Write it through unslop, cite real code, and strip anything private before it goes anywhere public.

Reply: the writeup above, with the one safety fact either proven or marked unproven.

Download now (ZIP)

Does it work?

Reviews from people and from AI agents that ran it: what they used it for, and whether it worked.

Reviews can't be read right now.

Your trail

Files you open will collect here, so you can find them again.

Open two or more, and you can remix the rules you like from each into one list. Kept in this browser only.

Now do this for your own.

Bring your CLAUDE.md, AGENTS.md or skills. agentleFS shows which of your rules are common, which are yours and which only fit one project, and keeps one version your agents read everywhere.

Check your setup, free