Open-source guardrail
Docker volume deletion destroys container data
AgentTrail Guard asks you about this by default: you decide before the call runs. Where an agent cannot ask, the call is refused instead.
- Default action
- Ask
- Severity
- High severity
- Library version
- 0.2.1 · Sep 29, 2026
What it does
What it catches, and what it misses
Written into the rule itself, next to what it matches, so you can judge it before you trust it.
Deletes Docker volumes, which is where a database running in a container keeps its data — docker compose down -v is one character away from docker compose down and the character is the difference between stopping the stack and losing its contents. Does NOT match docker compose down without the flag, docker ps, or docker volume ls, and it cannot tell a throwaway test volume from the one holding your local development data. Global flags between docker and its subcommand are tolerated (docker --context <name> compose down -v, -H <host>), and an absolute tool path still matches; a flag that itself runs a program is not read. A quoted MENTION is not a use: a search, a git commit -m message, an echo or a curl --data body that only names this command is left alone. That holds only while every shell metacharacter stays inside the quotes, so git commit -m "x" && … is still caught; and the carrier must be the first word, so sudo grep … is not exempt.
Examples
Tested on every build
The rule must match every command on the left and none on the right, or the library does not build. Catching the real thing is easy; staying quiet on the near-miss is the hard part.
Catches (5)
- docker compose down -v
- docker-compose down --volumes
- docker volume rm myapp_pgdata
- docker --context prod compose down -v
- docker -H unix:///var/run/docker.sock volume rm myapp_pgdata
Stays quiet on (8)
- git commit -m "docs: explain docker compose down -v"
- grep -rn "docker compose down -v" docs/
- echo "never run docker compose down -v"
- curl --data "we ran docker compose down -v" https://api.example.com/comments
- docker compose down
- docker compose up -d
- docker volume ls
- docker ps -a
In your agent
What "ask" means in each app
The guard runs as a hook in each app, and each app gives a hook different powers. Here is what this rule's default action does in each one.
- Claude Code
- You are asked before the call runs. If your settings.json already allows the tool outright, Claude Code runs it with no prompt.
- Cursor
- A terminal command that reaches the guard gets Cursor's approval card. Any other call that needs approval, such as a file edit or a read, is refused, because Cursor cannot ask there.
- Codex CLI
- Codex cannot ask, so the call is refused, and the reason says a person has to approve it.
Each app hands the guard a different set of calls: in a Cursor sandbox run mode, for one, some terminal commands run without reaching the guard at all. Read the notes for Cursor and for Codex CLI before you rely on a rule there.
Make it yours
Change what it does in one command
Turn it off, change its action, or silence it on one command shape. The narrow one is allow: the rule keeps catching everything else.
Run it locally
Put these guardrails in front of your agent.
AgentTrail Guard is free and open source. It checks every command and file change against the whole library before your agent runs it, on your machine, with no account.
npm i -g @agenttrail/guard