⚡ Faultline

Find hidden assumptions in code — before they break production.

A lightweight, deterministic static analyzer for JavaScript and Python that surfaces unsafe assumptions, implicit contracts, and fragile logic with clean, human-readable explanations.

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✨ What is Faultline?

Faultline analyzes your code and highlights assumptions you didn’t realize you were making.

Examples:

• Assuming fetch().json() always succeeds
• Assuming dict.get() never returns None
• Assuming a promise resolves to a specific type
• Assuming chained calls are always safe

Instead of flooding you with noise, Faultline collapses entire chains into one clean, actionable finding.

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🧠 Why Faultline exists

Most bugs don’t come from syntax errors.
They come from assumptions.

Faultline focuses on:

• 🔍 Signal over noise
• 🧠 Human-readable explanations
• 📏 Deterministic output (same input → same results)
• 🧩 Easy extensibility for future languages

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🚀 Features

Core

• ✅ JavaScript & Python support
• ✅ Deterministic findings
• ✅ Chain suppression (no duplicate noise)
• ✅ Friendly titles + explanations
• ✅ Suggested fixes
• ✅ Severity levels

JavaScript

• fetch().then(res => res.json())
• Response.json() / Response.text()
• Promise resolution inference
• Optional chaining handling

Python

• requests.get(...).json()
• dict.get() → possible None
• Safe built-in inference (MVP)

UI

• Clean, modern layout
• Loading animation
• Side-by-side editor & actions
• Analyze / Clear / Export
• No backend calls — browser-safe

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🖥️ Usage

Web UI

1. Paste your code
2. Select language (JS / Python)
3. Click Analyze
4. Review assumptions instantly

CLI (optional)

node index.js --lang js --file example.js
node index.js --lang python --file example.py --json
🧪 Testing
npm test
npm run test:coverage


All analyzers are fully tested with deterministic snapshots.

## 🔮 Future Plans

- Faultline is highly upgradable.

- Planned / on-demand expansions:

## 🌍 More languages (Go, Rust, Java, Lua)
## 📜 External rule definitions (JSON-driven)

## 🧠 Smarter inference via AST engines

## 🎨 More UI polish & exports

## 🧪 CI + GitHub

- New features can be added on demand without redesigning the core.

## 🤝 Contributing

- PRs are welcome.
- If you want to
- new language
- New inference rules

- UI improvements

- Open an issue first — let’s discuss.

## 📜 License

MIT License © 2026
Built with intent, not noise.


## ⚡ Faultline —
Because assumptions are where bugs are born.