Run a Claude Code review in CI with one claude -p line

A developer documented a method for running Claude Code as a non-interactive CI step using the CLI's headless mode, `claude -p`, which runs a single prompt, prints the result, and exits. The approach pipes a `git diff` into the prompt and uses `--allowedTools "Read,Grep"` to keep the run read-only and `--max-turns 3` to bound execution, then fails the build unless the output is exactly "LGTM". The writeup recommends storing the API key in repository secrets and running the check with `continue-on-error: true` for a week before making it block builds.

Most people only use Claude Code interactively. But the same CLI has a headless mode: claude -p "<prompt " runs one prompt, prints the answer, and exits. That makes it a normal script step you can drop into CI or a git hook. git diff origin/main...HEAD | claude -p "Review this diff. List real bugs only. If there are none, print exactly: LGTM" --output-format text Piped stdin becomes context, -p runs non-interactively, and the output is plain text you can grep. bash /usr/bin/env bash set -euo pipefail out=$ git diff origin/main...HEAD | claude -p \ "Review this diff for bugs, missing error handling and leaked secrets. If nothing is wrong, reply with exactly LGTM." \ --allowedTools "Read,Grep" --max-turns 3 echo "$out" "$out" == "LGTM" || exit 1 --allowedTools "Read,Grep" keeps the CI run read-only: it can look at files but not edit or run shell commands. --max-turns 3 caps how long it can wander. --output-format json and parse .result with jq . - name: Claude review env: ANTHROPIC API KEY: ${{ secrets.ANTHROPIC API KEY }} run: | npm i -g @anthropic-ai/claude-code ./scripts/claude-review.sh Keep the key in repository secrets, never in the script. CLAUDE.md and .claude/settings.json still load in headless mode, so your house rules apply in CI too. continue-on-error: true for a week before you let it fail builds. I keep copy-ready Claude Code configs CLAUDE.md templates, slash commands, hooks, permission rules in Vildanden Agent Config . There's a free sample: https://justly-mia-429.rehost.page/ https://justly-mia-429.rehost.page/