Universal zero-dependency linter and formatter. One pure-Rust binary (poly) that lints and formats ~30 languages in-process — ruff, oxc, biome, mago and more compiled in — with a tree-sitter tier for the long tail. One config, git hooks, and an MCP server for agents.
Agent
Implements a new poly engine backend end-to-end — empirically checks the upstream crate API, wraps it as a crates.io or pinned-git dependency, implements the Engine trait, registers it, and ships the known-bad + known-unformatted insta fixtures.
Agent
Reviews diffs touching poly's per-file runner / discovery / cache / engine paths for hot-path regressions — needless allocations/clones, missed borrows, parser-pool misuse, and non-rayon parallelism.