No Unknown Type Aliases

Error

small-rules/no-unknown-type-aliases

Disallow type aliases whose resolved type is unknown; unknown must remain visible at an allowed boundary.

Rationale

Ported from dmmulroy/anti-slop. Renaming unknown hides where parsing is still required. Keep it visible at the boundary, then introduce a real domain type after validation.

Diagnostic Messages

unknownAlias

Type alias `{{alias}}` hides `unknown`. Keep `unknown` explicit at the parsing boundary or on an allowed `cause` field; otherwise use the parsed owner type.

Configuration

This rule does not accept options.

.oxlintrc.json

{
  "jsPlugins": [
    "@pobammer-ts/small-rules"
  ],
  "rules": {
    "small-rules/no-unknown-type-aliases": "error"
  }
}

oxlint.config.ts

import { defineConfig } from "oxlint";

export default defineConfig({
  jsPlugins: ["@pobammer-ts/small-rules"],
  rules: {
    "small-rules/no-unknown-type-aliases": "error",
  },
});

Examples

renamed unknown alias

type ExternalValue = unknown;

specific type alias

type User = { readonly id: string };

Related Rules

RelatedNo Widen Then Assertno-unknown-type-aliases keeps unknown explicit at boundaries and pairs with no-widen-then-assert, which stops widening known locals then asserting back.