I let an AI agent into my repo. Here's what I lock down first.

An AI coding agent isn't autocomplete. It runs shell commands, reads your files, installs packages, and opens things you never pointed it at. That's the whole reason to have one. It's also why I don't start projects the way I used to. Nothing dramatic happened to me, by the way. I'm not writing this from the wreckage of a dropped production table. I'm writing it because I spent an afternoon going through what could plausibly go wrong, expecting a long list of hard problems, and instead found that most of it is handled by about ten minutes of config nobody mentions on day one. So here's the ten minutes. Prose isn't protection This is the bit that took me embarrassingly long to get. You can tell an agent things two ways. A rule is prose it reads and weighs - good for judgement calls like naming, style, when to stop and ask. A ban is a config entry that makes something impossible. The trap is using the first for the second job. Writing "never force-push" into a CLAUDE.md feels like a control. It isn't. It's a request sitting in a context window next to a few thousand other tokens, competing with whatever you actually asked for. It'll usually win. Usually is fine for naming conventions. It's not fine for git push --force . 1. The deny list .claude/settings.json : { "permissions" : { "deny" : [ "Bash(rm -rf:*)" , "Bash(git push --force:*)" , "Bash(git push -f:*)" , "Bash(git reset --hard:*)" , "Bash(psql*production*)" , "Bash(*DROP DATABASE*)" , "Bash(*DROP TABLE*)" , "Bash(*TRUNCATE*)" , "Read(./.env)" , "Read(./.env.local)" , "Read(./.env.*.local)" ] } } These don't run. Not "the agent is discouraged" - they don't run, including in the scenario the list exists for, which is you at midnight approving a plan you skimmed. Two things to know before you test it. It takes effect from the next session, not immediately. So you write the file, try the blocked command in the same session, watch it go through, and conclude the whole feature is broken. Restart first. Keep the .env