eslint.config.ts

import { PlatformCallDefaults, plugin, v8Plugin } from "@studnicky/eslint-config/node";
import stylistic from "@stylistic/eslint-plugin";
import importX from "eslint-plugin-import-x";
import perfectionistPlugin from "eslint-plugin-perfectionist";
import regexp from "eslint-plugin-regexp";
import sonarjs from "eslint-plugin-sonarjs";
import unusedImports from "eslint-plugin-unused-imports";
import { defineConfig } from "eslint/config";
import tseslint from "typescript-eslint";

const REPO_ROOT = decodeURIComponent(new URL(".", import.meta.url).pathname);
const TSCONFIG_ESLINT = `${REPO_ROOT}tsconfig.eslint.json`;
// node:assert is the test harness: its AssertionError is how node:test reports a failed test.
const TEST_PLATFORM_CALLS = PlatformCallDefaults.build().filter((entry) => {
  const isAssert = entry.owner === "assert" || entry.owner === "assert/strict";
  return !isAssert;
});

// Architectural bands, derived from the measured `@studnicky/*` dependency DAG rather than a
// borrowed hexagonal vocabulary: a package's band is the depth of its longest internal
// dependency chain. Each band may import its own band and any band below it, never above. That
// invariant already holds — the graph carries zero upward dependencies — so these rules codify
// what the code does rather than imposing a new constraint.
//
// `package` bindings resolve the band of the FILE being linted: in a flat monorepo the
// layer-bearing unit is the package, whose directory name sits after `sourceRoot` and before
// `src`. `module` bindings resolve the band of an IMPORT, so a cross-package specifier lands on
// the same band as the file it points at. `allowedImports` is stated explicitly rather than left
// to the positional default, which encodes hexagonal asymmetries that do not describe a strict
// linear-cumulative policy.
const SUBSTRATE_LAYERS = {
  allowedImports: {
    foundation: ["foundation"],
    primitive: ["foundation", "primitive"],
    capability: ["foundation", "primitive", "capability"],
    coordinator: ["foundation", "primitive", "capability", "coordinator"],
  },
  bindings: [
    { unit: "package", layer: "coordinator", pattern: "cache" },
    { unit: "package", layer: "capability", pattern: "circular-buffer" },
    { unit: "package", layer: "capability", pattern: "clock" },
    { unit: "package", layer: "coordinator", pattern: "concurrency" },
    { unit: "package", layer: "capability", pattern: "config" },
    { unit: "package", layer: "coordinator", pattern: "context" },
    { unit: "package", layer: "coordinator", pattern: "drilldown" },
    { unit: "package", layer: "foundation", pattern: "errors" },
    { unit: "package", layer: "capability", pattern: "eslint-config" },
    { unit: "package", layer: "coordinator", pattern: "event-bus" },
    { unit: "package", layer: "capability", pattern: "fetch" },
    { unit: "package", layer: "primitive", pattern: "filters" },
    { unit: "package", layer: "capability", pattern: "fsm" },
    { unit: "package", layer: "foundation", pattern: "entity" },
    { unit: "package", layer: "primitive", pattern: "json" },
    { unit: "package", layer: "capability", pattern: "logger" },
    { unit: "package", layer: "coordinator", pattern: "matching" },
    { unit: "package", layer: "capability", pattern: "pipeline" },
    { unit: "package", layer: "coordinator", pattern: "resilience" },
    { unit: "package", layer: "coordinator", pattern: "retry" },
    { unit: "package", layer: "coordinator", pattern: "scheduler" },
    { unit: "package", layer: "primitive", pattern: "signal" },
    { unit: "package", layer: "coordinator", pattern: "system" },
    { unit: "package", layer: "coordinator", pattern: "throttle" },
    { unit: "package", layer: "foundation", pattern: "types" },
    { unit: "package", layer: "capability", pattern: "virtual-fs" },
    { unit: "package", layer: "capability", pattern: "visible-range" },
    { unit: "package", layer: "coordinator", pattern: "worker-pool" },
    { unit: "module", layer: "coordinator", pattern: "@studnicky/cache" },
    { unit: "module", layer: "capability", pattern: "@studnicky/circular-buffer" },
    { unit: "module", layer: "capability", pattern: "@studnicky/clock" },
    { unit: "module", layer: "coordinator", pattern: "@studnicky/concurrency" },
    { unit: "module", layer: "capability", pattern: "@studnicky/config" },
    { unit: "module", layer: "coordinator", pattern: "@studnicky/context" },
    { unit: "module", layer: "coordinator", pattern: "@studnicky/drilldown" },
    { unit: "module", layer: "foundation", pattern: "@studnicky/errors" },
    { unit: "module", layer: "capability", pattern: "@studnicky/eslint-config" },
    { unit: "module", layer: "coordinator", pattern: "@studnicky/event-bus" },
    { unit: "module", layer: "capability", pattern: "@studnicky/fetch" },
    { unit: "module", layer: "primitive", pattern: "@studnicky/filters" },
    { unit: "module", layer: "capability", pattern: "@studnicky/fsm" },
    { unit: "module", layer: "foundation", pattern: "@studnicky/entity" },
    { unit: "module", layer: "primitive", pattern: "@studnicky/json" },
    { unit: "module", layer: "capability", pattern: "@studnicky/logger" },
    { unit: "module", layer: "coordinator", pattern: "@studnicky/matching" },
    { unit: "module", layer: "capability", pattern: "@studnicky/pipeline" },
    { unit: "module", layer: "coordinator", pattern: "@studnicky/resilience" },
    { unit: "module", layer: "coordinator", pattern: "@studnicky/retry" },
    { unit: "module", layer: "coordinator", pattern: "@studnicky/scheduler" },
    { unit: "module", layer: "primitive", pattern: "@studnicky/signal" },
    { unit: "module", layer: "coordinator", pattern: "@studnicky/system" },
    { unit: "module", layer: "foundation", pattern: "@studnicky/types" },
    { unit: "module", layer: "capability", pattern: "@studnicky/virtual-fs" },
    { unit: "module", layer: "capability", pattern: "@studnicky/visible-range" },
    { unit: "module", layer: "coordinator", pattern: "@studnicky/worker-pool" },
  ],
  layers: ["foundation", "primitive", "capability", "coordinator"],
  sourceRoot: "packages",
};

const FILTERS_MATCHING_LAYERS = {
  allowedImports: {
    foundation: ["foundation"],
    primitive: ["foundation", "primitive"],
    capability: ["foundation", "primitive", "capability"],
    coordinator: ["foundation", "primitive", "capability", "coordinator"],
  },
  bindings: [
    { unit: "folder", layer: "coordinator", pattern: "matching" },
    { unit: "module", layer: "foundation", pattern: "@studnicky/errors" },
    { unit: "module", layer: "coordinator", pattern: "@studnicky/matching" },
    { unit: "module", layer: "foundation", pattern: "@studnicky/types" },
  ],
  layers: ["foundation", "primitive", "capability", "coordinator"],
  sourceRoot: "packages/filters/src",
};

export default [
  {
    // Architectural bands and the error contract govern package source and tests. Examples are
    // consumers — like any downstream application they compose across the whole toolkit, and
    // `packages/fsm/examples` imports `@studnicky/scheduler`, a package that depends on `fsm`.
    files: ["packages/*/src/**/*.ts", "packages/*/tests/**/*.ts"],
    plugins: { "@studnicky": plugin },
    rules: {
      // The other four `arch/*` rules stay OFF, measured rather than assumed. All four encode
      // "a business-logic core with a conversion boundary around it"; substrate has neither —
      // four bands of utility and infrastructure code, no domain layer, and no intake boundary
      // separate from where a dependency is already wrapped.
      //
      //   known-types-outside-adapters  587 violations at best band choice, 1144 at worst.
      //     `unknown` is this repo's own narrowing idiom, ~1177 uses across every band, the
      //     deliberate alternative to `any`. The heaviest packages (`json`, `errors`) sit in
      //     bands no choice of adapter layer exempts. Defensive typing INSIDE every layer is
      //     the toolkit's value, not a failure to convert at one edge.
      //   adapter-only-import           0 or 3, depending which band plays "adapters".
      //     The 3 are `fetch` importing `undici` — but `fetch` IS the adapter wrapping `undici`
      //     for the toolkit; there is no further layer to hide it behind. One adapter-shaped
      //     dependency exists across all 43 packages, so the rule has almost no surface here.
      //   domain-purity                 1 violation: `BaseError`'s `Date.now()` timestamp,
      //     which is legitimate. No band is a domain layer; `foundation` is the closest only
      //     by being lowest, and it holds error handling and types, not business rules.
      //   no-threaded-vocabulary        250 violations across 109 files (sourceRoot: 'packages').
      //     The rule expects a resolution site that exchanges a closed-vocabulary token for a
      //     port implementation; substrate has no port/adapter architecture for a token to
      //     resolve INTO, so a mode/kind/type enum threaded through an ordinary parameterized
      //     utility function is ubiquitous and legitimate here, not an unresolved token.
      //
      // `layer-import-boundary` is enabled because substrate genuinely HAS what it describes —
      // a dependency-depth hierarchy with an enforceable upward-import ban — which is why it
      // reports zero against real code instead of hundreds against real idioms.
      "@studnicky/adapter-only-import": [
        "error",
        { ...SUBSTRATE_LAYERS, adapterLayerName: "capability" },
      ],
      "@studnicky/domain-purity": ["error", { ...SUBSTRATE_LAYERS, domainLayerName: "foundation" }],
      "@studnicky/layer-import-boundary": ["error", SUBSTRATE_LAYERS],
      // Every error a published package emits is a named BaseError subclass.
      "@studnicky/no-native-error": "error",
    },
  },
  {
    files: ["packages/filters/src/matching/**/*.ts"],
    rules: {
      "@studnicky/layer-import-boundary": ["error", FILTERS_MATCHING_LAYERS],
    },
  },
  { ignores: [".claude/**", ".enginseer/**"] },
  ...defineConfig(
    {
      ignores: ["docs/.vitepress/cache/**", "**/dist/**", "**/node_modules/**", "**/*.d.ts"],
    },
    {
      files: ["packages/*/src/**/*.ts", "packages/*/tests/**/*.ts", "packages/*/examples/**/*.ts"],
      languageOptions: {
        parser: tseslint.parser,
        parserOptions: {
          projectService: true,
          tsconfigRootDir: REPO_ROOT,
        },
      },
      linterOptions: {
        reportUnusedDisableDirectives: "error",
      },
      plugins: {
        "@studnicky": plugin,
        "@studnicky/v8": v8Plugin,
        "@stylistic": stylistic,
        "import-x": importX,
        perfectionist: perfectionistPlugin,
        regexp: regexp,
        sonarjs: sonarjs,
        "unused-imports": unusedImports,
        ...(tseslint.plugin !== null && tseslint.plugin !== undefined
          ? { "@typescript-eslint": tseslint.plugin }
          : {}),
      },
      rules: {
        // @studnicky custom rules
        "@studnicky/all-types-are-entities": "error",
        "@studnicky/clean-diagnostics": "error",
        "@studnicky/descriptive-identifiers": "error",
        "@studnicky/direct-invocation-only": "error",
        "@studnicky/explicit-return-binding": "error",
        "@studnicky/entity-file-shape": "error",
        "@studnicky/hash-private-fields": "error",
        "@studnicky/inline-trivial-logic": "error",
        "@studnicky/intake-parse-only": [
          "error",
          {
            exemptPackages: [
              "@studnicky/types",
              "@studnicky/eslint-config",
              "@studnicky/entity",
              "@studnicky/drilldown",
            ],
          },
        ],
        "@typescript-eslint/no-unnecessary-type-parameters": "error",
        "@studnicky/interface-must-be-contract": "error",
        "@studnicky/export-shape": "error",
        "@studnicky/interfaces-compose-named-types": "error",
        "@studnicky/lexical-this-only": "error",
        "@studnicky/no-caller-chosen-guard-type": "error",
        "@studnicky/no-circular-imports": "error",
        "@studnicky/no-double-assertion": "error",
        "@studnicky/no-function-registries": "error",
        "@studnicky/no-mixed-callable-shapes": "error",
        "@studnicky/no-redefined-external-types": "error",
        "@studnicky/no-reflect-argument-laundering": "error",
        "@studnicky/no-unchecked-overload-implementation": "error",
        "@studnicky/no-unparsed-assertion": "error",
        "@studnicky/prefer-collection-types": "error",
        "@studnicky/require-options-object": "error",
        "@studnicky/static-method-verbs": "error",
        "@studnicky/type-alias-invariants": "error",
        // @studnicky/v8 optimisation rules
        "@studnicky/v8/arguments-object": "error",
        "@studnicky/v8/array-concat-outside-loops": "error",
        "@studnicky/v8/array-from-iterators": "error",
        "@studnicky/v8/array-from-map-callback": "error",
        "@studnicky/v8/array-scan-outside-loops": "error",
        "@studnicky/v8/array-splice-outside-loops": "error",
        "@studnicky/v8/array-spread-outside-loops": "error",
        "@studnicky/v8/chained-array-iteration": "error",
        "@studnicky/v8/computed-class-properties": "error",
        "@studnicky/v8/computed-object-properties": "error",
        "@studnicky/v8/conditional-property-assignment": "error",
        "@studnicky/v8/define-property": "error",
        "@studnicky/v8/delete-property": "error",
        "@studnicky/v8/dynamic-property-access": "error",
        "@studnicky/v8/eval-function": "error",
        "@studnicky/v8/for-in-loops": "error",
        "@studnicky/v8/for-of-arrays": "error",
        "@studnicky/v8/inline-arrow-functions": "error",
        "@studnicky/v8/inline-functions": "error",
        "@studnicky/v8/max-switch-cases": "error",
        "@studnicky/v8/memoize-array-length": "error",
        "@studnicky/v8/object-spread": "error",
        "@studnicky/v8/prototype-modification": "error",
        "@studnicky/v8/regexp-in-loops": "error",
        "@studnicky/v8/switch-statements": "error",
        "@studnicky/v8/try-catch-in-loops": "error",
        "@studnicky/v8/with-statement": "error",
        // @stylistic
        "@stylistic/comma-dangle": ["error", "never"],
        "@stylistic/eol-last": ["error", "always"],

        "@stylistic/indent": ["error", 2],
        "@stylistic/no-trailing-spaces": "error",
        "@stylistic/quote-props": ["error", "always"],
        "@stylistic/quotes": ["error", "single", { avoidEscape: true }],
        "@stylistic/semi": ["error", "always"],
        // @typescript-eslint — auto-fixable set
        "@typescript-eslint/array-type": ["error", { default: "array" }],
        "@typescript-eslint/await-thenable": "error",
        "@typescript-eslint/consistent-type-exports": "error",
        "@typescript-eslint/consistent-type-imports": [
          "error",
          { fixStyle: "separate-type-imports" },
        ],
        "@typescript-eslint/dot-notation": "error",
        "@typescript-eslint/naming-convention": [
          "error",
          {
            custom: { match: true, regex: "Interface$|^Type$" },
            format: ["PascalCase"],
            selector: "interface",
          },
          {
            format: ["PascalCase"],
            selector: "typeAlias",
          },
        ],
        "@typescript-eslint/no-duplicate-type-constituents": "error",
        "@typescript-eslint/no-explicit-any": ["error", { fixToUnknown: true }],
        "@typescript-eslint/no-floating-promises": "error",
        "@typescript-eslint/no-inferrable-types": "error",
        "@typescript-eslint/no-meaningless-void-operator": "error",
        "@typescript-eslint/no-misused-promises": [
          "error",
          { checksVoidReturn: { inheritedMethods: false } },
        ],
        "@typescript-eslint/no-redundant-type-constituents": "error",
        "@typescript-eslint/no-unnecessary-type-assertion": "error",
        "@typescript-eslint/no-unnecessary-type-constraint": "error",
        "@typescript-eslint/no-unsafe-assignment": "error",
        "@typescript-eslint/no-unused-vars": [
          "error",
          {
            // `_`-prefixed args are intentionally-unused parameters on no-op
            // template-method/lifecycle hooks that subclasses override.
            argsIgnorePattern: "^_",
            varsIgnorePattern: "^(_|[A-Z][A-Za-z]*Schema$|[A-Za-z]*Interface$|[A-Za-z]*Type$)",
          },
        ],
        "@typescript-eslint/no-useless-empty-export": "error",
        "@typescript-eslint/non-nullable-type-assertion-style": "error",
        "@typescript-eslint/prefer-as-const": "error",
        "@typescript-eslint/prefer-function-type": "off",
        "@typescript-eslint/prefer-nullish-coalescing": "error",
        "@typescript-eslint/prefer-optional-chain": "error",
        "@typescript-eslint/require-await": "error",
        "@typescript-eslint/return-await": ["error", "always"],
        "@typescript-eslint/strict-boolean-expressions": [
          "error",
          {
            allowNullableObject: false,
            allowNumber: false,
            allowString: false,
          },
        ],
        // Core
        "arrow-body-style": ["error", "always"],
        "consistent-return": "error",
        curly: ["error", "all"],
        eqeqeq: ["error", "always"],
        // import-x
        "import-x/newline-after-import": "error",
        "import-x/no-default-export": "error",
        "no-array-constructor": "error",
        "no-case-declarations": "error",
        "no-class-assign": "error",
        "no-cond-assign": ["error", "always"],
        "no-console": "error",
        "no-const-assign": "error",
        "no-constant-condition": "error",
        "no-debugger": "error",
        "no-duplicate-case": "error",
        "no-duplicate-imports": ["error", { allowSeparateTypeImports: true }],
        "no-else-return": ["error", { allowElseIf: false }],
        "no-eq-null": "error",
        "no-eval": "error",
        "no-extra-bind": "error",
        "no-func-assign": "error",
        "no-global-assign": "error",
        "no-implicit-coercion": "error",
        "no-implicit-globals": "error",
        "no-invalid-regexp": "error",
        "no-lonely-if": "error",
        "no-multi-assign": "error",
        complexity: ["error", 10],
        "max-depth": ["error", 4],
        "max-lines": ["error", { max: 1000, skipBlankLines: true, skipComments: true }],
        "max-lines-per-function": ["error", { max: 120, skipBlankLines: true, skipComments: true }],
        "max-params": ["error", 5],
        "no-nested-ternary": "error",
        "sonarjs/cognitive-complexity": ["error", 15],
        "no-new-func": "error",
        "no-new-wrappers": "error",
        "no-object-constructor": "error",
        "no-prototype-builtins": "error",
        "no-template-curly-in-string": "error",
        "no-throw-literal": "error",
        "no-unexpected-multiline": "error",
        "no-unreachable": "error",
        "no-unsafe-negation": "error",
        "no-unused-expressions": "error",
        "no-var": "error",
        "object-shorthand": ["error", "never"],
        "one-var": ["error", "never"],
        "perfectionist/sort-array-includes": ["error", { order: "asc", type: "natural" }],
        "perfectionist/sort-classes": "off",
        "perfectionist/sort-decorators": ["error", { order: "asc", type: "natural" }],
        // Perfectionist sorting
        "perfectionist/sort-enums": "error",
        "perfectionist/sort-exports": "error",
        "perfectionist/sort-heritage-clauses": ["error", { order: "asc", type: "natural" }],
        "perfectionist/sort-imports": "error",
        "perfectionist/sort-interfaces": "error",
        "perfectionist/sort-intersection-types": ["error", { order: "asc", type: "natural" }],
        "perfectionist/sort-maps": ["error", { order: "asc", type: "natural" }],
        "perfectionist/sort-modules": "off",
        "perfectionist/sort-named-exports": "error",
        "perfectionist/sort-named-imports": "error",
        "perfectionist/sort-object-types": "error",
        "perfectionist/sort-objects": "error",
        "perfectionist/sort-sets": ["error", { order: "asc", type: "natural" }],
        "perfectionist/sort-switch-case": ["error", { order: "asc", type: "natural" }],
        "perfectionist/sort-union-types": "off",
        "perfectionist/sort-variable-declarations": ["error", { order: "asc", type: "natural" }],
        "prefer-const": "error",
        "prefer-rest-params": "error",
        "prefer-spread": "error",
        "prefer-template": "error",
        // regexp
        "regexp/no-unused-capturing-group": "error",

        "regexp/no-useless-flag": "error",

        "regexp/prefer-regexp-exec": "error",
        "require-yield": "error",
        // unused-imports
        "unused-imports/no-unused-imports": "error",
      },
    },
    // Tooling — scripts, CI helpers and the docs site are procedural CLI/build code, not
    // published package surfaces, so the package-authoring rules (entity shape, static-method
    // dispatch, descriptive-identifier banlist) do not apply. Correctness, type-safety and
    // style rules stay fully enforced.
    {
      files: ["scripts/**/*.ts", ".github/**/*.ts", "docs/**/*.ts"],
      languageOptions: {
        parser: tseslint.parser,
        parserOptions: {
          projectService: true,
          tsconfigRootDir: REPO_ROOT,
        },
      },
      linterOptions: {
        reportUnusedDisableDirectives: "error",
      },
      plugins: {
        "@stylistic": stylistic,
        "import-x": importX,
        perfectionist: perfectionistPlugin,
        regexp: regexp,
        sonarjs: sonarjs,
        "unused-imports": unusedImports,
        ...(tseslint.plugin !== null && tseslint.plugin !== undefined
          ? { "@typescript-eslint": tseslint.plugin }
          : {}),
      },
      rules: {
        // @stylistic
        "@stylistic/comma-dangle": ["error", "never"],
        "@stylistic/eol-last": ["error", "always"],
        "@stylistic/indent": ["error", 2],
        "@stylistic/no-trailing-spaces": "error",
        "@stylistic/quote-props": ["error", "always"],
        "@stylistic/quotes": ["error", "single", { avoidEscape: true }],
        "@stylistic/semi": ["error", "always"],
        // @typescript-eslint — auto-fixable set
        "@typescript-eslint/array-type": ["error", { default: "array" }],
        "@typescript-eslint/await-thenable": "error",
        "@typescript-eslint/consistent-type-exports": "error",
        "@typescript-eslint/consistent-type-imports": [
          "error",
          { fixStyle: "separate-type-imports" },
        ],
        "@typescript-eslint/dot-notation": "error",
        "@typescript-eslint/naming-convention": [
          "error",
          {
            custom: { match: true, regex: "Interface$|^Type$" },
            format: ["PascalCase"],
            selector: "interface",
          },
          {
            format: ["PascalCase"],
            selector: "typeAlias",
          },
        ],
        "@typescript-eslint/no-duplicate-type-constituents": "error",
        "@typescript-eslint/no-explicit-any": ["error", { fixToUnknown: true }],
        "@typescript-eslint/no-floating-promises": "error",
        "@typescript-eslint/no-inferrable-types": "error",
        "@typescript-eslint/no-meaningless-void-operator": "error",
        "@typescript-eslint/no-misused-promises": [
          "error",
          { checksVoidReturn: { inheritedMethods: false } },
        ],
        "@typescript-eslint/no-redundant-type-constituents": "error",
        "@typescript-eslint/no-unnecessary-type-assertion": "error",
        "@typescript-eslint/no-unnecessary-type-constraint": "error",
        "@typescript-eslint/no-unsafe-assignment": "error",
        "@typescript-eslint/no-unused-vars": [
          "error",
          {
            argsIgnorePattern: "^_",
            varsIgnorePattern: "^(_|[A-Z][A-Za-z]*Schema$|[A-Za-z]*Interface$|[A-Za-z]*Type$)",
          },
        ],
        "@typescript-eslint/no-useless-empty-export": "error",
        "@typescript-eslint/non-nullable-type-assertion-style": "error",
        "@typescript-eslint/prefer-as-const": "error",
        "@typescript-eslint/prefer-function-type": "off",
        "@typescript-eslint/prefer-nullish-coalescing": "error",
        "@typescript-eslint/prefer-optional-chain": "error",
        "@typescript-eslint/require-await": "error",
        "@typescript-eslint/return-await": ["error", "always"],
        "@typescript-eslint/strict-boolean-expressions": [
          "error",
          {
            allowNullableObject: false,
            allowNumber: false,
            allowString: false,
          },
        ],
        // Core
        "arrow-body-style": ["error", "always"],
        "consistent-return": "error",
        curly: ["error", "all"],
        eqeqeq: ["error", "always"],
        // import-x
        "import-x/newline-after-import": "error",
        "import-x/no-default-export": "error",
        "no-array-constructor": "error",
        "no-case-declarations": "error",
        "no-class-assign": "error",
        "no-cond-assign": ["error", "always"],
        "no-const-assign": "error",
        "no-constant-condition": "error",
        "no-debugger": "error",
        "no-duplicate-case": "error",
        "no-duplicate-imports": ["error", { allowSeparateTypeImports: true }],
        "no-else-return": ["error", { allowElseIf: false }],
        "no-eq-null": "error",
        "no-eval": "error",
        "no-extra-bind": "error",
        "no-func-assign": "error",
        "no-global-assign": "error",
        "no-implicit-coercion": "error",
        "no-implicit-globals": "error",
        "no-invalid-regexp": "error",
        "no-lonely-if": "error",
        "no-multi-assign": "error",
        complexity: ["error", 10],
        "max-depth": ["error", 4],
        "max-lines": ["error", { max: 1000, skipBlankLines: true, skipComments: true }],
        "max-lines-per-function": ["error", { max: 120, skipBlankLines: true, skipComments: true }],
        "max-params": ["error", 5],
        "no-nested-ternary": "error",
        "sonarjs/cognitive-complexity": ["error", 15],
        "no-new-func": "error",
        "no-new-wrappers": "error",
        "no-object-constructor": "error",
        "no-prototype-builtins": "error",
        "no-template-curly-in-string": "error",
        "no-throw-literal": "error",
        "no-unexpected-multiline": "error",
        "no-unreachable": "error",
        "no-unsafe-negation": "error",
        "no-unused-expressions": "error",
        "no-var": "error",
        "object-shorthand": ["error", "never"],
        "one-var": ["error", "never"],
        "perfectionist/sort-array-includes": ["error", { order: "asc", type: "natural" }],
        "perfectionist/sort-classes": "off",
        "perfectionist/sort-decorators": ["error", { order: "asc", type: "natural" }],
        "perfectionist/sort-enums": "error",
        "perfectionist/sort-exports": "error",
        "perfectionist/sort-heritage-clauses": ["error", { order: "asc", type: "natural" }],
        "perfectionist/sort-imports": "error",
        "perfectionist/sort-interfaces": "error",
        "perfectionist/sort-intersection-types": ["error", { order: "asc", type: "natural" }],
        "perfectionist/sort-maps": ["error", { order: "asc", type: "natural" }],
        "perfectionist/sort-modules": "off",
        "perfectionist/sort-named-exports": "error",
        "perfectionist/sort-named-imports": "error",
        "perfectionist/sort-object-types": "error",
        "perfectionist/sort-objects": "error",
        "perfectionist/sort-sets": ["error", { order: "asc", type: "natural" }],
        "perfectionist/sort-switch-case": ["error", { order: "asc", type: "natural" }],
        "perfectionist/sort-union-types": "off",
        "perfectionist/sort-variable-declarations": ["error", { order: "asc", type: "natural" }],
        "prefer-const": "error",
        "prefer-rest-params": "error",
        "prefer-spread": "error",
        "prefer-template": "error",
        // regexp
        "regexp/no-unused-capturing-group": "error",
        "regexp/no-useless-flag": "error",
        "regexp/prefer-regexp-exec": "error",
        "require-yield": "error",
        // unused-imports
        "unused-imports/no-unused-imports": "error",
      },
    },
    // Test files — type-aware against tsconfig.eslint.json, which includes every package's tests.
    {
      files: ["packages/*/tests/**/*.ts"],
      languageOptions: {
        parserOptions: {
          project: [TSCONFIG_ESLINT],
          projectService: false,
          tsconfigRootDir: REPO_ROOT,
        },
      },
      rules: {
        "@studnicky/no-native-error": ["error", { platformCalls: TEST_PLATFORM_CALLS }],
      },
    },
    // Config and framework entrypoints their loader requires to default-export.
    {
      files: [
        "eslint.config.*",
        "*.config.*",
        "docs/.vitepress/config.ts",
        "docs/.vitepress/theme/index.ts",
      ],
      rules: {
        "@studnicky/export-shape": "off",
        "import-x/no-default-export": "off",
      },
    },
    // Example files — runnable demos. Full type-aware rigor via the dedicated
    // tsconfig.eslint.json, relaxing only rules that govern library authoring
    // (single-export modules) or that conflict with a demo's purpose (console
    // output). Correctness, type-safety, and style rules stay fully enforced.
    {
      files: ["packages/*/examples/**/*.ts"],
      languageOptions: {
        parserOptions: {
          project: [TSCONFIG_ESLINT],
          projectService: false,
          tsconfigRootDir: REPO_ROOT,
        },
      },
      rules: {
        "@studnicky/export-shape": "off",
        "import-x/no-default-export": "off",
        "no-console": "off",
      },
    },
    // CLI tools write to stdout/stderr as their interface, not as debug residue.
    {
      files: ["scripts/**/*.ts", ".github/**/*.ts"],
      rules: {
        "no-console": "off",
      },
    },
  ),
  // Only these files are permitted to use `console` directly. ConsoleTransport
  // is the logger's own console sink; all other logger-producing modules must
  // route output through it. EventRecorder is deliberately raw, dependency-free
  // console output — example/demo glue any package can use without pulling in
  // @studnicky/logger as a dependency.
  {
    files: [
      "packages/logger/src/transports/ConsoleTransport.ts",
      "packages/errors/src/observers/EventRecorder.ts",
    ],
    rules: {
      "no-console": "off",
    },
  },
  // The playground evaluator's entire purpose is running transpiled example source
  // with an injected require shim — `new Function` is the mechanism, not a workaround.
  {
    files: ["docs/.vitepress/theme/utils/playgroundRuntime.ts"],
    rules: {
      "no-new-func": "off",
    },
  },
  // drilldown's matcher registry implements one shared interface (MatcherHandlerInterface) via
  // plain object literals, not classes — the rule's own class-implementation exemption doesn't
  // reach a handful of per-type methods (getSortKey, createNodeValue) that are genuinely pure
  // field forwards by design (the interface contract IS "expose this field"). allowMemberExpressions
  // is the rule's own documented escape valve for exactly this member-forward shape.
  {
    files: ["packages/drilldown/src/**/*.ts"],
    rules: {
      "@studnicky/inline-trivial-logic": ["error", { allowMemberExpressions: true }],
    },
  },
];