Check Before Commit

Check Before Commit

Pre-commit sensitive information scanner. Adapts behavior based on repo visibility.

Trigger

• Automatically before commit-commands:commit
• Manual: /check-before-commit

Workflow

Step 1: Detect repo visibility

Run:

gh repo view --json visibility --jq .visibility 2>/dev/null

• If returns PUBLIC → strict mode (block on findings)
• If returns PRIVATE or INTERNAL → warn mode (report but don't block)
• If fails → ask user: "Can't detect repo visibility. Is this a public or private repo?"

Step 2: Get staged changes

Run:

git diff --cached

If no staged changes, report "No staged changes to scan" and exit.

Step 3: Load allowlist (optional)

Check for .claude/allowlist.json in project root. If exists, load the allowed array. Items in the allowlist are skipped during scanning.

Step 4: Scan staged changes

Layer 1: Regex scan (deterministic)

Scan the diff output for these patterns:

Secrets & credentials:

sk-(live|test|proj)-[a-zA-Z0-9]{20,}
AKIA[0-9A-Z]{16}
ghp_[a-zA-Z0-9]{36}
gho_[a-zA-Z0-9]{36}
xox[bpras]-[a-zA-Z0-9-]{10,}
-----BEGIN (RSA |EC |DSA |OPENSSH )?PRIVATE KEY-----
-----BEGIN PGP (PRIVATE KEY BLOCK|SIGNATURE)-----

Infrastructure:

# Private IPs
10\.\d{1,3}\.\d{1,3}\.\d{1,3}
172\.(1[6-9]|2\d|3[01])\.\d{1,3}\.\d{1,3}
192\.168\.\d{1,3}\.\d{1,3}

# Local paths (non-generic)
/Users/[^/\s]+/[^\s]*(?!\.(git|npm|cache))
/C/Users/[^/\s]+/
/home/[^/\s]+/

# Database connection strings
(postgres|mysql|mongodb|redis)://[^\s]+:[^\s]+@

Sensitive config files (check staged filenames):

.env
.env.*
*.pem
*.key
*.p12
*.pfx
.npmrc
.netrc
.ssh/
credentials
service-account*.json

For each regex match:

1. Check if the matched value is in the allowlist → skip if yes
2. Otherwise record as finding

Layer 2: Semantic scan (Claude judgment)

Review the diff content for PII that regex can't reliably catch:

• Phone numbers (especially Chinese mobile: 1[3-9]\d{9})
• National ID numbers (身份证号)
• Real personal names in comments or config (not variable names or git authors)
• Personal email addresses in non-git-config context

Use context to distinguish:

• var userName = "test" → OK, variable value
• // Contact 张三 at 13800138000 → finding, PII in comment
• sk-test-1234 in test fixture → check allowlist, suggest adding if not present

Step 5: Report findings

No findings: Output: "No sensitive information detected. Safe to commit." → Allow commit to proceed.

Findings + PUBLIC repo (strict mode): Block the commit. Output each finding with:

• File and line
• Category (secret / infrastructure / PII / config file)
• The matched content (partially masked for secrets)
• Suggested action (remove / add to allowlist / use env variable)

Wait for user to fix or explicitly override.

Findings + PRIVATE repo (warn mode): List the findings as a warning. Output same details but don't block. User can proceed or choose to fix.

Allowlist Management

When a finding is a false positive, suggest:

"This appears to be a test/example value. Add to .claude/allowlist.json to skip in future scans?"

Format of .claude/allowlist.json:

{
  "allowed": [
    "sk-test-xxx",
    "example@company.com",
    "10.0.0.1"
  ]
}

If the file doesn't exist, offer to create it when the first false positive is found.

Integration with commit-commands:commit

When triggered as part of the commit workflow:

1. Run this scan first
2. If scan blocks (public repo + findings) → stop, don't commit
3. If scan passes → proceed to normal commit flow