Claude Code mod blast-radius

For rm -r, rm -f and rm -rf, the pane lists the files it would delete, with the count and total size. For git reset --hard, it lists the files with uncommitted changes and the git diff --shortstat. For git checkout -- . and git restore ., the files with unstaged changes. For git clean, the untracked paths it would remove, from git clean -n with the same flags.

For git push --force (also -f, --force-with-lease and +ref), it lists the commits on the remote branch that your HEAD doesn't have, which the push would drop. For manage.py migrate, db:migrate, alembic upgrade and prisma migrate, it lists the pending migrations from the tool's own status command. Any other migrate gets a note that it can't list them.

If the command line moves first, with cd dir &&, pushd or popd, or git -C dir, it measures in that folder.

The hooks module is hooks/blast-radius.mjs, and hooks/hooks.json points to it. It registers three hooks.

tool.call on the Bash tool: holds a risky call until you answer, then lets it run or returns { deny } with a reason Claude can act on. The README says a hook has a 10-second budget for its own code and that time inside a $ call doesn't count, so the hold is a loop that waits on $.process.run with sleep until a button sets the decision.

ui.render on the Pane component: draws the report and the two buttons in a pane opened with $.ui.open.

ui.render on the AbovePrompt component: draws the same report in the band above the prompt when the terminal is too narrow for a pane.

It measures with $.process.run, passing paths as arguments so nothing in them runs as shell.

The README asks for Claude Code 2.1.287 or later, where mods load by default. Check yours with claude --version. It needs no environment variables or configuration.

Run these from the claude-code/mods folder of a clone (see Download the source). The first command checks the plugin and lists its hooks. The second loads it for one session only.

To keep it, add the folder as a local marketplace and install it from claude-code-playground-mods, as the last two commands do. The official mods overview notes that this marketplace points at your clone, so the mod stops loading if you move or delete the clone.

If you install it from your shell while a session is open, run /reload-plugins in that session to load it. To confirm it loaded, run /plugin: a dim line under the tabs names the mods the session loaded.

It also needs bash, git, find and du on your PATH, and for migrations the project's own tool (for example python3 manage.py showmigrations). For the side pane, a terminal about 144 columns wide or more. Narrower terminals get the band above the prompt.

The README suggests trying it in a throwaway repository, for example by asking Claude to delete the build folder with rm -rf build. To remove it, run claude plugin uninstall blast-radius@claude-code-playground-mods --scope user.

The source lives in the claude-code/mods/blast-radius folder of the anthropics/claude-code-playground repository, beside the two other sample mods. The README's steps clone the whole repository and go to the mods folder, which is the folder the set up commands run from.

The repository's LICENSE is the Apache License 2.0, and the hooks module carries the header SPDX-License-Identifier: Apache-2.0. The repository README says the DevRel team maintains it, that entries are provided as is with no support and no guarantee they still work, and that it is not accepting outside contributions yet.

Press 1 for Proceed or 2 for Cancel. You can also click a button, or Tab to it and press Enter. Cancel has the focus when the pane opens, so Enter refuses the command. In the band above the prompt, 1 or 2 works while the input is empty.

If nobody answers within 10 minutes, or you interrupt the turn with Esc, the command is refused. One command is held at a time: a second risky call waits until the first is answered.

It reads the command text and doesn't parse shell fully. The README lists what it misses, including $(...), aliases, eval, bash -c, xargs rm, find -delete, scripts that call rm, and wrappers such as timeout or env.

Only the first risky part of a command line is measured, and Proceed runs the whole line as written. It only watches the Bash tool: file edits and other tools aren't held. It holds a call but doesn't sandbox it.

To list pending migrations it runs the tool's own status command, which loads your project's code before you choose. In a narrow terminal it needs the band above the prompt, which only one mod can use at a time: if another mod takes the band, the buttons may not show and the command is refused after 10 minutes.