feat(eslint-plugin-runner): new package for ESLint plugin compatibility runtime

Adds @rslint/eslint-plugin-runner as a self-contained npm package. The
runner runs unmodified ESLint plugin rules inside Node worker_threads
spawned by a future host (CLI / LSP server). No upstream caller in this
PR — package can be imported and used independently.

Surface
- WorkerPool: queued task model, per-task SharedArrayBuffer cancel flag,
  worker_threads lifecycle (spawn / respawn-on-crash / shutdown drain),
  per-task timeout + terminate path
- LintWorker entry: imports user rslint configs directly, extracts live
  plugin instances per configDirectory, dispatches lint tasks by
  configKey
- ESLint v10 surface fills: Rule.Context, SourceCode (lazy tokens +
  getDisableDirectives), scope-manager / visitor-keys integration,
  oxc-parser preserveParens:false to match espree
- Tokenizer (tokenizer.ts + tokenizer-jsx.ts): JS / TS lexer with
  paren/brace context tracking, Unicode-escape identifiers, regex /
  template / private-identifier scans. JSX is opt-in via
  TokenizeOptions.jsx — separate state machine in tokenizer-jsx.ts
  emits JSXIdentifier / JSXText / Punctuator per espree's contract;
  TSX disambiguation rejects generic shapes (`<T,>`, `<T extends X>`,
  `<T>(…)`) from JSX entry
- IPC client: framed protocol for the future host's reverse-RPC
- compat-task-builder: pure helpers projecting LSP/CLI wire shapes to
  internal lint tasks

Tests
- 336 tests across 18 files, all pass standalone:
  - worker-pool-e2e: queue model, cancel, timeout/respawn, shutdown
    drain, postMessage failure modes, multi-worker mid-respawn race
  - context-api / source-code / scope-factory / normalize-ast /
    listener-merge / plugin-loader / cancel-flag / ipc-client /
    language-options / lazy-cache / compat-task-builder
  - regression-coverage: behavior-pinning tests across the v10
    compatibility surface — disable-directive line/block carrier
    contract, drain semantics under multi-worker respawn (including
    mid-init crash), fix() result validation (array/iterable/string),
    tokenizer regex-vs-division context tracking, Unicode-escape
    identifiers, BOM stripping, unified bare+esquery specificity
    dispatch, TS scope globalReturn + commonjs parity, .mts/.cts JSX
    promotion, interpolate.js message template parity,
    getInlineConfigNodes / getDisableDirectives line-vs-block +
    label-boundary rules, boundary token getters returning null,
    options deep-clone, init failure-on-any-rejection, getIndexFromLoc
    throwing on invalid / out-of-range loc
  - jsx-tokenizer: 72 espree-oracle differential tests covering basic
    elements, attributes (name-only / string / expression / spread),
    JSXText, dotted / namespaced / hyphenated names, nesting,
    fragments, expression containers, template-literal interaction,
    `<` disambiguation (comparison / shift / TSX generics), and
    non-JSX regression

Build
- Standalone: \`pnpm --filter @rslint/eslint-plugin-runner build && test\`
- ESM-only ("type": "module"), runtime deps: @typescript-eslint/{scope-manager,
  visitor-keys}, oxc-parser; devDep: espree (test oracle); peerDep: jiti

Author: fansenze

.github/workflows/ci.yml

@@ -155,6 +155,7 @@ jobs:
           pnpm --filter @rslint/core run build:js
           pnpm --filter @typescript-eslint/rule-tester build
           pnpm --filter rslint build
+          pnpm --filter @rslint/eslint-plugin-runner build
 
       - name: VSCode Test Cache
         uses: lynx-infra/cache@5c6160a6a4c7fca80a2f3057bb9dfc9513fcb732

package.json

@@ -13,7 +13,7 @@
   },
   "license": "MIT",
   "scripts": {
-    "build": "pnpm -r --filter=@rslint/test-tools... --filter=rslint... build",
+    "build": "pnpm -r --filter=@rslint/test-tools... --filter=rslint... --filter=@rslint/eslint-plugin-runner build",
     "build:npm": "zx scripts/build-npm.mjs",
     "build:website": "pnpm --filter @rslint/core run build:js && pnpm --filter=!@rslint/core --filter @rslint/website... -r build",
     "bench:cli": "pnpm --filter rslint-bench-cli run bench",
@@ -25,7 +25,7 @@
     "publish:ovsx": "zx scripts/publish-marketplace.mjs --marketplace=ovsx",
     "format": "prettier --write .",
     "format:check": "prettier --check .",
-    "test": "pnpm -r --filter=@rslint/test-tools... --filter=rslint... test",
+    "test": "pnpm -r --filter=@rslint/test-tools... --filter=rslint... --filter=@rslint/eslint-plugin-runner test",
     "test:go": "go test ./internal/...",
     "typecheck": "pnpm tsgo -b tsconfig.json",
     "lint": "rslint --config rslint.config.ts",

packages/eslint-plugin-runner/README.md

@@ -0,0 +1,29 @@
+# @rslint/eslint-plugin-runner
+
+Internal ESLint-plugin compatibility runtime for [rslint](https://github.com/web-infra-dev/rslint).
+
+This package is **not** intended for direct end-user consumption. It is embedded
+by `@rslint/core` (CLI) and the VS Code extension to execute ESLint plugin rules
+on a Node `worker_threads` pool, while the rslint Go binary drives the lint
+pipeline.
+
+## Why a separate package
+
+`@rslint/core` is a thin CLI / API wrapper around the Go binary. The pieces that
+must run inside Node — plugin loading, oxc-parser → ESTree normalization, scope
+analysis, fixer / suggestion plumbing, IPC framing — live here so:
+
+- `@rslint/core` keeps a small surface and can be loaded fast even when no
+  ESLint plugin is configured.
+- The same runtime is reusable by the VS Code extension's in-process
+  `WorkerPool`, where Go is the LSP server and Node is the LSP client.
+
+## Stability
+
+The exports are an implementation detail of rslint's plugin compatibility
+layer. They may change in any minor release without a deprecation cycle. If you
+need to embed rslint in your own tool, use `@rslint/core` instead.
+
+## License
+
+MIT

packages/eslint-plugin-runner/package.json

@@ -0,0 +1,70 @@
+{
+  "name": "@rslint/eslint-plugin-runner",
+  "version": "0.5.2",
+  "description": "ESLint-plugin compatibility runtime for rslint — Worker pool, per-file lint pipeline, scope manager. Embedded by the CLI (@rslint/core) and by the VS Code extension; not invoked as a standalone process.",
+  "type": "module",
+  "repository": {
+    "type": "git",
+    "url": "git+https://github.com/web-infra-dev/rslint.git",
+    "directory": "packages/rslint-eslint-plugin-runner"
+  },
+  "license": "MIT",
+  "publisher": "rslint",
+  "keywords": [
+    "rslint",
+    "eslint",
+    "eslint-plugin",
+    "linter",
+    "internal"
+  ],
+  "exports": {
+    ".": {
+      "@typescript/source": "./src/index.ts",
+      "default": "./dist/index.js"
+    },
+    "./ipc-client": {
+      "@typescript/source": "./src/ipc-client.ts",
+      "default": "./dist/ipc-client.js"
+    },
+    "./types": {
+      "@typescript/source": "./src/types.ts",
+      "default": "./dist/types.js"
+    }
+  },
+  "files": [
+    "dist",
+    "README.md"
+  ],
+  "publishConfig": {
+    "access": "public"
+  },
+  "engines": {
+    "node": ">=20"
+  },
+  "scripts": {
+    "build": "rslib build",
+    "test": "rstest run"
+  },
+  "devDependencies": {
+    "@eslint/plugin-kit": "0.3.5",
+    "@rslib/core": "0.21.2",
+    "@rstest/core": "0.9.2",
+    "@types/node": "24.0.14",
+    "espree": "11.2.0"
+  },
+  "dependencies": {
+    "@typescript-eslint/scope-manager": "8.59.4",
+    "eslint-scope": "9.1.2",
+    "esquery": "1.7.0",
+    "globals": "17.6.0",
+    "oxc-parser": "0.132.0"
+  },
+  "peerDependencies": {
+    "jiti": "^2.0.0"
+  },
+  "peerDependenciesMeta": {
+    "jiti": {
+      "optional": true
+    }
+  }
+}

packages/eslint-plugin-runner/rslib.config.ts

@@ -0,0 +1,90 @@
+import { defineConfig } from '@rslib/core';
+
+/**
+ * Build configuration for `@rslint/eslint-plugin-runner`.
+ *
+ * Each library is its own `lib` block so Rspack treats them as
+ * independent builds — that means each output file gets the entire
+ * reachable module graph inlined and there are no `dist/<hash>.js`
+ * shared chunks between entries. Crucial for the worker entry, which
+ * is loaded via `new Worker(workerEntryPath)`: the worker spawns a
+ * fresh V8 isolate and pays a filesystem-open + parse cost for every
+ * additional chunk it has to load. Splitting `lint-worker.js` into a
+ * thin 10 KB stub plus a 158 KB shared chunk doubled the worker's
+ * boot-time disk reads for no shared-cache benefit (each worker is
+ * its own isolate; modules can't be reused across them).
+ *
+ * `oxc-parser` is the only runtime dep that MUST stay external — it
+ * uses a NAPI loader (`src-js/bindings.js`) that resolves its
+ * platform-specific `.node` binary relative to `import.meta.url`;
+ * bundling its loader would repoint that URL at our bundle file and
+ * the native binary lookup would fail.
+ *
+ * Five outputs map 1:1 to the package.json `exports` field:
+ *
+ *   - `index.js`        — main entry, host integration
+ *   - `lint-worker.js`  — worker_threads entry (resolved by sibling
+ *                          lookup inside `worker-pool.ts`, so the file
+ *                          MUST land at `dist/lint-worker.js`)
+ *   - `ipc-client.js`   — Go-side stdio framing helpers
+ *   - `types.js`        — shared type re-exports
+ */
+const baseLib = {
+  format: 'esm' as const,
+  bundle: true,
+  // All three categories external — runtime deps come from the user's
+  // node_modules (correct version resolution + tree-shareable), peerDeps
+  // are explicitly host-supplied. Only devDependencies bundle into dist.
+  //
+  // Two source-level idioms tacitly rely on this:
+  //   - `@typescript-eslint/scope-manager` / `visitor-keys` are loaded
+  //     via `createRequire(import.meta.url)` (CJS packages on an ESM
+  //     entry). Static `import` would tempt a future contributor and
+  //     `autoExternal: { dependencies: false }` would silently bundle
+  //     them.
+  //   - `oxc-parser` is ESM with a NAPI loader that resolves its
+  //     platform `.node` next to `import.meta.url`; bundling repoints
+  //     that URL at our dist file and breaks the native binary lookup.
+  autoExternal: true,
+  output: {
+    target: 'node' as const,
+  },
+  source: {
+    tsconfigPath: './tsconfig.build.json',
+  },
+};
+
+export default defineConfig({
+  lib: [
+    {
+      ...baseLib,
+      source: { ...baseLib.source, entry: { index: './src/index.ts' } },
+      // Bundle dts only on the main entry — the other entries either
+      // re-export from `index` or are tiny standalone modules; emitting
+      // independent dts for each would duplicate the same types five
+      // times. The main `dist/index.d.ts` covers all public surface.
+      dts: { bundle: true },
+    },
+    {
+      ...baseLib,
+      source: {
+        ...baseLib.source,
+        entry: { 'lint-worker': './src/lint-worker.ts' },
+      },
+      dts: false,
+    },
+    {
+      ...baseLib,
+      source: {
+        ...baseLib.source,
+        entry: { 'ipc-client': './src/ipc-client.ts' },
+      },
+      dts: { bundle: true },
+    },
+    {
+      ...baseLib,
+      source: { ...baseLib.source, entry: { types: './src/types.ts' } },
+      dts: { bundle: true },
+    },
+  ],
+});