PrePr — Stop Risky Pull Requests Before They Merge

PrePr analyzes your git diff and predicts PR merge risk before code review begins.

⚡ See PrePr in Action

One command to get started

npx prepr-cli init

Creates a GitHub Action, config file, and ignore rules in your repo. Open a PR — PrePr runs automatically.

Who is this for?

✅ Teams reviewing large, fast-moving PRs
✅ Startups without strict review gates
✅ Security-sensitive services (auth, payments, infra)
✅ Repos with many contributors and frequent merges
✅ Any team that has merged a PR that caused a production incident

Zero config. Any language. Instant results.

⚡ Works on any language — diff-based, not AST-based
⚡ No repo changes required to start
⚡ Runs in under 2 seconds
⚡ 8 built-in rules covering PR size, risky files, missing tests, debug artifacts
⚡ Blocks merge automatically when HIGH risk detected

GitHub PR Comment (automatic)

Every PR gets a risk summary posted automatically:

🔍 PrePr Risk Report

Score: 55/100
Merge Risk: 🚫 HIGH

| Severity | Count |
|----------|-------|
| 🔴 High   | 1     |
| 🟡 Medium | 2     |
| 🟢 Low    | 1     |

🔥 Fix Order
1. Request security review for risky file (+20 pts)
2. Add tests for changed modules (+10 pts)

Your CI checks show:

✅ Tests passed
✅ Build passed
❌ PrePr Risk Analysis — HIGH risk detected

What the terminal output looks like

Running PrePr scan...

PrePr Report
────────────────────────

🔴 HIGH
   ℹ️ Auth/payment/config files historically cause production incidents.
   Risky file modified: src/auth/loginService.ts

🟡 MEDIUM
   ℹ️ Source changes without test coverage increase regression risk.
   7 source file(s) modified but no test files updated

   src/index.ts:59
      // TODO remove debug logic

Score Breakdown
---------------
Risky file modified            -20
Missing tests                  -10
TODO comments                  -10
────────────────────────────────────
Final Score                55/100

🚨 Needs Attention
   ✓ Request security review for auth/risky changes
   ✓ Add tests for changed modules

🔥 Fix Order (highest impact first)
   1. Request security review for risky file  (+20 pts)
   2. Add tests for changed modules           (+10 pts)
   3. Resolve TODO/FIXME comments             (+10 pts)

Try PrePr instantly

Fork this demo repo and open a PR to see PrePr analyze your changes automatically:

👉 prepr-demo-risky-pr

Install

# No install required — run directly
npx prepr-cli scan

# Or install globally
npm install -g prepr-cli

GitHub Action Marketplace

Use PrePr directly as a GitHub Action:

- uses: abhirajthealmighty/PrePr@main
  with:
    base-branch: main
    fail-on-high: "true"

Setup in your repo

cd your-project
npx prepr-cli init

Creates:

• .github/workflows/prepr.yml — GitHub Action that runs on every PR
• prepr.config.json — configure rules, base branch, ignored paths
• .preprignore — paths to exclude from analysis

Commit these files. PrePr runs automatically on every PR.

Built-in Rules

| Rule | What it detects | Severity | |------|-----------------|----------| | large-pr | PRs over 300 added lines | 🔴 High | | risk-concentration | One file has >60% of PR changes | 🔴 High | | dependency-change | package.json, go.mod, requirements.txt modified | 🔴 High | | risky-file | Auth, payment, config, infrastructure files modified | 🔴 High | | missing-test | Source changes without test file updates | 🟡 Medium | | todo-detector | TODO/FIXME/HACK in added lines (comment-only) | 🟡 Medium | | large-function | >80 consecutive added lines without a break | 🟡 Medium | | debug-artifact | console.log, debugger, printStackTrace etc. | 🟢 Low |

Configuration

// prepr.config.json
{
  "baseBranch": "main",
  "maxPRLines": 300,
  "ignore": ["dist/", "node_modules/", "coverage/", ".prepr/"],
  "rules": {
    "large-pr": true,
    "missing-test": false,
    "todo-detector": true
  }
}

Why PrePr

| Tool | What it checks | |------|---------------| | ESLint | Code syntax and style | | Tests | Functional correctness | | SonarCloud | Code quality metrics | | DangerJS | Custom PR rules (config-heavy) | | PrePr | Merge risk — zero config, any language |

CLI Reference

prepr scan                    # Scan current diff vs main
prepr scan --base develop     # Diff against a different branch
prepr scan --html             # Generate .prepr/report.html
prepr scan --format json      # Structured JSON output (for CI)
prepr scan --github           # Post comment to GitHub PR

prepr init                    # Set up PrePr in this repo
prepr install                 # Install pre-push git hook

JSON output for custom CI

prepr scan --format json > prepr-result.json

{
  "score": 55,
  "risk": "NEEDS_ATTENTION",
  "riskLabel": "Needs Attention",
  "summary": { "high": 1, "medium": 2, "low": 1 },
  "metrics": { "filesChanged": 14, "linesAdded": 451 },
  "fixPriority": [
    { "action": "Request security review for risky file", "gain": 20 }
  ]
}

Contributing

git clone https://github.com/abhirajthealmighty/PrePr
cd PrePr
npm install
npm run dev      # Run in development
npm run build    # Compile TypeScript

PRs welcome — especially new rules, language-specific patterns, and CI integrations.

License

ISC © abhirajthealmighty