Oxlint rules that demand receipts for every type assertion

What it does

anti-slop is a set of custom Oxlint rules for TypeScript and JavaScript that flag patterns the author considers weakly typed or evidentially sloppy. It targets things like chained type assertions, unknown function parameters and return types, runtime typeof narrowing, and even Vitest or Jest module mocks. The whole package is designed to be copied—vendored—directly into your repository rather than installed as a traditional dependency.

The interesting bit

The project treats linting as a team standard you should own outright. A bundled agent skill automates the initial copy-and-configure ritual, but the README insists you then read the rules, change them, and maintain the vendored code yourself. It is less a library and more a manifesto against both loose typing and invisible upstream updates.

Key highlights

• Fifteen opinionated rules, including bans on Reflect.apply, object parameters, shape in symbol names, and widening a value only to assert it back later.
• Requires a // SAFETY: comment justifying every non-const type assertion, forcing explicit documentation of invariants.
• Offers an escape hatch for no-runtime-typeof via allowInTypeGuards, acknowledging that schema-free projects sometimes need pragmatic boundaries.
• Ships with a skills.sh agent skill to handle the initial vendoring, Oxlint dependency installation, and config merging.

Verdict

Best for teams using Oxlint who want an aggressive, opinionated baseline against TypeScript’s more permissive patterns. If your codebase relies heavily on unknown, module mocking, or ad hoc type assertions, expect a fight.