| name | poly-lint-format |
| description | Reference for poly, the single-binary multi-language linter and formatter — per-language engines, the lint/fmt commands, poly.toml configuration, severity behavior, and the shared CI validation workflow. Load when linting or formatting code, configuring poly.toml, or wiring poly into CI. |
Poly
Poly is a single-binary multi-language linter and formatter. It bundles language engines (ruff for Python, oxc for JS/TS/JSON, taplo for TOML, rumdl for Markdown) and delegates to native tools (cargo fmt, cargo clippy, golangci-lint, actionlint, shellcheck, shfmt) when present. Most repos need no extra toolchains. Configure via per-repo poly.toml.
Engines by language
| Scope | Engine(s) |
|---|
| Python | ruff (lint + format), pyrefly (type check) |
| JS/TS/JSON/CSS | oxc (lint + format) |
| TOML | taplo (lint + format) |
| Markdown | rumdl (format) |
| Rust | cargo fmt + cargo clippy (via cargo hook) |
| Go | golangci-lint |
| Java | checkstyle, maven verify |
| Ruby | rubocop (format + lint) |
| C# | dotnet format |
| PHP | php-cs-fixer, phpstan |
| Elixir | mix format, mix credo |
| R | styler, lintr |
| C/C++ | clang-format, cppcheck |
| Shell | shfmt, shellcheck |
| Git | gitfluff (commit message linting), ai-rulez-generate |
| GH Actions | actionlint |
| Helm/K8s | helm-lint, kubeconform |
Commands
- Lint:
poly lint .
- Check formatting (dry-run):
poly fmt --check .
- Apply formatting:
poly fmt --fix .
- Apply lint autofixes:
poly lint --fix .
Configuration
Per-repo poly.toml defines linting and formatting rules:
[discovery] — exclude globs[lint.<lang>.<tool>] — select/ignore rules, settings like pydocstyle_convention, line_length[per-file-ignores] — file-specific exemptions[fmt.<lang>.<tool>] — formatter options[hooks.builtin] — git hook configuration
Cache directory .polylint/ is gitignored.
Severity
poly lint exits non-zero only on error-severity findings. Warnings are reported but do not fail CI.
CI
Run linting and formatting validation in CI via the shared reusable workflow:
uses: xberg-io/actions/.github/workflows/reusable-validate.yml@v1
This workflow runs poly fmt --check . then poly lint . with optional inputs setup-rust and setup-python.
Always run poly fmt --check . and poly lint . after making changes to verify compliance.
