anti-slop

Opinionated Oxlint rules that reject low-evidence and low-signal TypeScript and JavaScript patterns.

This project is meant to be vendored, not treated as a fixed npm dependency. Copy the rules into your repository, read them, and change them to match your team's standards. The bundled agent skill handles the initial copy and configuration; after that, the vendored files are yours to maintain and make your own.

Install with an agent skill

npx skills add dmmulroy/anti-slop --skill install-anti-slop

Then ask your coding agent to install or configure anti-slop in the current repository. The skill copies the plugin, installs current Oxlint dependencies, merges the plugin into the existing lint configuration, enables every rule, and validates the result.

To inspect available skills first:

npx skills add dmmulroy/anti-slop --list

Manual local installation

Copy src/ into the target repository, for example at tools/oxlint/anti-slop/, and install matching current versions of oxlint and @oxlint/plugins.

import { defineConfig } from "oxlint";

export default defineConfig({
  ignorePatterns: [
    ".agent/**",
    ".agents/**",
    ".claude/**",
    ".codex/**",
    ".continue/**",
    ".cursor/**",
    ".gemini/**",
    ".opencode/**",
    ".pi/**",
    ".roo/**",
    ".windsurf/**",
    "tools/oxlint/anti-slop/**",
  ],
  jsPlugins: [
    { name: "anti-slop", specifier: "./tools/oxlint/anti-slop/index.ts" },
  ],
  rules: {
    "anti-slop/no-chained-type-assertions": "error",
    "anti-slop/no-conditional-empty-object-spread": "error",
    "anti-slop/no-known-value-widening": "error",
    "anti-slop/no-module-mocking": "error",
    "anti-slop/no-object-parameters": "error",
    "anti-slop/no-reflect-apply": "error",
    "anti-slop/no-reflect-get": "error",
    "anti-slop/no-runtime-typeof": "error",
    "anti-slop/no-shape-in-symbol-names": "error",
    "anti-slop/no-unknown-parameters": "error",
    "anti-slop/no-unknown-returns": "error",
    "anti-slop/no-unknown-type-aliases": "error",
    "anti-slop/no-unsafe-dictionary-type": "error",
    "anti-slop/no-widen-then-assert": "error",
    "anti-slop/require-safety-comment-for-type-assertion": "error"
  }
});

The same ignorePatterns, jsPlugins, and rules work under lint in a Vite+ config. Merge the ignore patterns into Vite+'s fmt.ignorePatterns as well so vp check does not reformat installed agent assets or the vendored plugin. Preserve existing ignores and add any other project-local agent tooling directories detected in the repository; do not broadly ignore every dot-directory.

Rules

no-chained-type-assertions — rejects nested type assertions that fabricate evidence.
no-conditional-empty-object-spread — rejects conditional spreads that use {} to omit fields.
no-known-value-widening — rejects explicit broad target types that discard known value evidence.
no-module-mocking — rejects Vitest and Jest module mocks in favor of real dependency seams.
no-object-parameters — rejects the broad object type on function inputs.
no-reflect-apply — rejects Reflect.apply in favor of typed function calls.
no-reflect-get — rejects Reflect.get in favor of typed property access or boundary parsing.
no-runtime-typeof — requires boundary parsing instead of ad hoc typeof narrowing.
no-shape-in-symbol-names — rejects shape in symbol names.
no-unknown-parameters — rejects unknown inputs except the explicit cause convention.
no-unknown-returns — rejects function contracts that return unknown or Promise<unknown>.
no-unknown-type-aliases — rejects aliases that merely conceal unknown.
no-unsafe-dictionary-type — rejects dictionary value contracts based on unknown, any, object, {}, and semantic equivalents.
no-widen-then-assert — rejects local flows that widen known values and later assert them back.
require-safety-comment-for-type-assertion — requires each non-const assertion to document its checked invariant.

Violation examples

Each snippet below is rejected by the named rule.

`no-chained-type-assertions`

const user = input as object as User;

`no-conditional-empty-object-spread`

const options = {
  ...(timeout !== undefined ? { timeout } : {}),
};

`no-known-value-widening`

const handlers: Record<string, Handler> = {
  start: startHandler,
};

This discards the known start key. Preserve inference or use satisfies Record<string, Handler> instead.

`no-module-mocking`

vi.mock("./user-store");

`no-object-parameters`

function save(value: object) {}

`no-reflect-apply`

const value = Reflect.apply(operation, owner, args);

`no-reflect-get`

const value = Reflect.get(owner, key);

`no-runtime-typeof`

if (typeof input === "string") {
  useName(input);
}

Schema-free projects can permit typeof checks directly inside type predicate and assertion functions while continuing to reject ad hoc checks elsewhere:

{
  "anti-slop/no-runtime-typeof": [
    "error",
    { "allowInTypeGuards": true }
  ]
}

The option defaults to false.

`no-shape-in-symbol-names`

interface UserShape {
  id: string;
}

`no-unknown-parameters`

function handle(input: unknown) {}

`no-unknown-returns`

function loadUser(): unknown {
  return input;
}

`no-unknown-type-aliases`

type ExternalValue = unknown;

`no-unsafe-dictionary-type`

type Metadata = Record<string, unknown>;
type OtherMetadata = { [key: string]: object };

`no-widen-then-assert`

const loaded: User = loadUser();
const stored: unknown = loaded;
const user = stored as User;

`require-safety-comment-for-type-assertion`

const userId = value as UserId;

Add a specific justification immediately before a necessary assertion:

// SAFETY: parseUserId validated the identifier before branding it.
const userId = value as UserId;

Development

pnpm install
pnpm check

src/ is canonical. After changing production source, run pnpm sync:skill-assets; CI checks that the skill's bundled copy remains identical.

License

MIT

Anti Slop

At a glance

README