Rules catalog

Sextant ships seven built-in rules covering size, complexity, duplication, and tests. They’re embedded in the binary and load automatically — no .sextant/rules/ entries required.

Rule id	Severity	Languages	Summary
builtin.size.file-length	warn	all	File exceeds line-count thresholds.
builtin.size.fn-length	warn	rust, python, go, java, ts/tsx/js	Function body too long.
builtin.size.param-count	warn	rust, python, go, java, ts/tsx/js	Too many parameters on one function.
builtin.complexity.cyclomatic	warn	rust, python, go, java, ts/tsx/js	Too many independent control-flow paths.
builtin.complexity.nesting	warn	rust, python, go, java, ts/tsx/js	Deeply nested control structures.
builtin.duplication.tokens	warn	rust, python, go, java, ts/tsx/js	Repeated structurally-identical code.
builtin.tests.pub-fn-untested	info	rust, ts/tsx/js	Public function or exported declaration never mentioned in a test, in-file or in a conventional peer test file.

All seven are file-scope, so they fire in both diff and whole-file mode (with diff-mode filtering findings to changed lines). Tune their thresholds in .sextant/config.toml.

Authoring your own

Authoring rules covers the full schema for .sextant/rules/<name>.md files — regex, ast, and llm evaluators, frontmatter fields, validation flow.

Installing a rule pack

For curated rule sets shipped by another team (or another repo of yours), see Rule packs. Packs are hash-locked, agent-resistant bundles installed via sextant rules add github:owner/repo@tag. The first shipped pack is the TypeScript pack.

See also

• Rule concept — the data model.
• Authoring rules — write your own.
• Rule packs — install or author a shareable rule bundle.
• sextant rules — list, explain, validate, install.