Fallow

Fallow is a Rust-native CLI that builds a project-wide graph of a TypeScript/JavaScript codebase and surfaces what file-local linters can't — unused exports/files/dependencies, cross-module circular deps, boundary violations, duplication (strict → semantic clones), complexity hotspots, and architecture drift — with sub-second analysis and 90 framework plugins. Positioned as 'the codebase truth layer your coding agent can call' rather than an AI assistant itself: agents invoke it via the CLI, a structured JSON output, or the MCP integration to get deterministic evidence on AI-generated changes before opening a PR. Free + MIT-licensed static core; optional paid Runtime layer ingests V8/Istanbul production coverage to tell teams which paths are hot vs cold for higher-confidence review and deletion. Ships a GitHub Action, GitLab CI template, VS Code extension, and SARIF/CodeClimate/markdown outputs for PR annotations.