Automate Pre-Commit Code Reviews with Claude Code Git Hooks

Claude Code git hooks: automate code review before every commit

Claude Code enables developers to integrate automated AI reviews directly into the .git/hooks/pre-commit lifecycle. This system utilizes the claude-opus-4-5 model to scan staged diffs for critical bugs and security vulnerabilities before any code is committed.

Why This Matters

Technical linters are limited to syntax and style, often missing deep logic errors like race conditions or idempotent API misuse. While direct API usage for every commit can cost between $2 and $9 monthly based on volume, switching to flat-rate proxies like SimplyLouie makes continuous AI-driven verification economically viable for individual engineering workflows.

Key Insights

• Logic error detection: Claude identifies issues such as thread-safety risks and unhandled edge cases that standard static analysis tools overlook.
• Cost optimization via SimplyLouie: Routing Claude API calls through a flat-rate proxy reduces the cost of 20+ daily commits to a $2/month fixed fee (2026).
• Reviewdog integration: Automated reviews can be piped into Reviewdog to generate local reports in standard formats like golint.
• Policy enforcement with CLAUDE.md: Documenting git policies in CLAUDE.md ensures the AI agent respects blocking keywords such as CRITICAL, security, or data loss.

Working Examples

A pre-commit hook that sends staged changes to Claude and blocks the commit if critical issues are found.

#!/bin/bash
DIFF=$(git diff --cached --unified=3)
if [ -z "$DIFF" ]; then
exit 0
fi
REVIEW=$(curl -s https://api.anthropic.com/v1/messages \
-H "Content-Type: application/json" \
-H "x-api-key: $ANTHROPIC_API_KEY" \
-H "anthropic-version: 2023-06-01" \
-d "{
\"model\": \"claude-opus-4-5\",
\"max_tokens\": 500,
\"messages\": [{
\"role\": \"user\",
\"content\": \"Review this git diff for critical issues only (bugs, security, data loss). If clean, respond with LGTM. If issues found, list them briefly.\\n\\n$DIFF\"
}]
}" | jq -r '.content[0].text' 2>/dev/null)
echo "Claude review: $REVIEW"
if echo "$REVIEW" | grep -qi "CRITICAL\|security\|data loss\|SQL injection\|XSS"; then
echo "❌ Commit blocked by Claude review"
exit 1
fi
echo "✅ Claude review passed"
exit 0

Configuration for CLAUDE.md to ensure AI awareness of the git hook policy.

## Git Policy
- All commits reviewed by pre-commit hook
- Hook blocks on CRITICAL/security/data loss keywords
- Run `git commit --no-verify` only for WIP commits
- Hook uses claude-opus-4-5 via ANTHROPIC_BASE_URL proxy

Practical Applications

• Use Case: Anthropic API integration for high-fidelity code reviews; Pitfall: Pay-per-token pricing can lead to high monthly costs (up to $9/month) for high-frequency committers.
• Use Case: SimplyLouie flat-rate proxy usage; Pitfall: Introducing a dependency on an external API proxy for the core git commit workflow.

References:

• https://dev.to/subprime2010/claude-code-git-hooks-automate-code-review-before-every-commit-30cc