Sanity

Sanity is a software design tool for developers and coding agents.

Use Cases

• Build maintainable software
• Understand codebases
• Audit AI-generated code
• Stabilize and reclaim apps built with AI

Quick Start

Step 1: Install with npm (cross-platform):

npm install -g @legacycodehq/sanity

Or install on macOS/Linux using Homebrew:

brew install sanity

Step 2: Inside your project:

sanity setup  # Add usage instructions to AGENTS.md for your coding agent

For other installation methods (pre-built binaries, build from source, Go install), see the Installation Guide.

The Problem

Every time a coding agent makes changes to your codebase, you have the following questions:

• Which files should I review first and in what order?
• Where should I spend most of my review effort?
• What is the blast radius of this change?
• Which parts of the change are too risky?
• How does this solution fit into the existing system?
• Are there adequate tests for these changes?

These concerns worsen when there are:

• Too many files to review
• You have an outdated mental model of your codebase

How Sanity Helps

Sanity uses a file-based dependency graph to visualize the impact of AI-generated changes, showing you:

• The files changed and the relationships between them
• The order to review files (simple answer: review from right-to-left)
• Color-coded files by extension to help you quickly categorize and group them for review
• Test files at a glance
• An accurate mental model of the system as you evolve it

See Sanity in Action

Sanity works with Desktop and IDE coding agents. If you are using a CLI coding agent, the agent can open diagrams in your browser for review.

Sanity shows impacted files and highlights tests in green.

Supported Languages

• C
• C++
• C#
• Dart
• Go
• JavaScript
• Java
• Kotlin
• Python
• Ruby
• Rust
• Swift
• TypeScript

License

This project is licensed under the GNU Affero General Public License v3.0.