Replace ESLint with oxlint

.chronus/changes/migrate-to-oxlint-2026-6-16-11-50-0.md

@@ -0,0 +1,15 @@
+---
+changeKind: internal
+packages:
+  - "@azure-tools/typespec-autorest"
+  - "@azure-tools/typespec-autorest-canonical"
+  - "@azure-tools/typespec-azure-core"
+  - "@azure-tools/typespec-azure-portal-core"
+  - "@azure-tools/typespec-azure-resource-manager"
+  - "@azure-tools/typespec-azure-rulesets"
+  - "@azure-tools/typespec-client-generator-core"
+  - "@azure-tools/typespec-metadata"
+  - "@azure-tools/typespec-ts"
+---
+
+Migrate linting from ESLint to oxlint.

.github/matchers/oxlint.json

@@ -0,0 +1,19 @@
+{
+  "problemMatcher": [
+    {
+      "owner": "oxlint",
+      "severity": "error",
+      "pattern": [
+        {
+          "regexp": "^(.+?):(\\d+):(\\d+):\\s+(.+?)\\s+\\[(Error|Warning)/(.+)\\]$",
+          "file": 1,
+          "line": 2,
+          "column": 3,
+          "message": 4,
+          "severity": 5,
+          "code": 6
+        }
+      ]
+    }
+  ]
+}

.github/workflows/consistency.yml

@@ -99,10 +99,14 @@ jobs:
       - run: pnpm install
         name: Install dependencies
 
-      - run: pnpm --filter="@typespec/eslint-plugin..." run  build
-        name: Build prettier plugin
-
-      - run: pnpm run lint
+      # Force the `unix` reporter (instead of oxlint's default GitHub Actions
+      # reporter) so the full `file:line:col` location stays visible in the job
+      # logs, and register a problem matcher so violations still surface as
+      # inline annotations on the PR.
+      - name: Add oxlint Problem Matcher
+        run: echo "::add-matcher::.github/matchers/oxlint.json"
+
+      - run: pnpm run lint:ci
         name: Lint
 
       - run: pnpm run lint:extra

.vscode/extensions.json

@@ -1,6 +1,6 @@
 {
   "recommendations": [
-    "dbaeumer.vscode-eslint",
+    "oxc.oxc-vscode",
     "esbenp.prettier-vscode",
     "streetsidesoftware.code-spell-checker",
     "vitest.explorer",

oxlint.config.ts

@@ -0,0 +1,83 @@
+import { defineConfig } from "oxlint";
+import { TypeSpecCommonOxlintConfigs } from "./core/oxlint.config.ts";
+
+const {
+  allFilesRules,
+  typescriptFileOverride,
+  jsxFilesOverride,
+  testFilesOverride,
+  typeAwareOverride,
+} = TypeSpecCommonOxlintConfigs;
+
+export default defineConfig({
+  plugins: ["typescript", "unicorn"],
+  categories: {
+    correctness: "off",
+  },
+  env: {
+    builtin: true,
+  },
+  ignorePatterns: [
+    "**/dist/**/*",
+    "**/.temp/**/*",
+    "**/temp/**/*",
+    "**/generated-defs/*",
+    "**/website/build/**/*",
+    "**/.astro/**/*",
+    // The TypeSpec core submodule has its own oxlint config - don't lint it from here.
+    "core/**/*",
+    // Ignore python virtual env
+    "**/venv/**/*",
+    // Ignore VSCode test web project
+    "**/.vscode-test-web/**/*",
+    // TODO: enable
+    "**/.scripts/**/*",
+    "eng/scripts/**/*",
+    "packages/*/scripts/**/*",
+    "**/typespec-ts/test/*/generated/**/*",
+    "**/src/modular/static/**/*",
+  ],
+  rules: allFilesRules,
+  overrides: [
+    typescriptFileOverride,
+    jsxFilesOverride,
+    testFilesOverride,
+    {
+      // typespec-ts has static helper files which are copied verbatim into generated output and
+      // intentionally keep camelCase names to match the upstream Azure SDK sources.
+      files: ["**/packages/typespec-ts/static/**/*.ts", "**/packages/typespec-ts/static/**/*.mts"],
+      rules: {
+        "unicorn/filename-case": "off",
+      },
+    },
+    {
+      // Generated by `npm run gen:scenario-suites`. The file names encode the scenario
+      // directory tree with `__` separators (e.g. `models__nested-enum__not-flatten`), so
+      // they intentionally don't follow kebab-case.
+      files: ["**/packages/typespec-ts/test/modular-unit/scenario-suites/**/*.test.ts"],
+      rules: {
+        "unicorn/filename-case": "off",
+      },
+    },
+    {
+      // Astro route files (e.g. `[...path]/[llms_type].txt.ts`) use framework-required naming.
+      files: ["**/website/src/pages/**/*.ts", "**/website/src/components/**/*.ts"],
+      rules: {
+        "unicorn/filename-case": "off",
+      },
+    },
+    {
+      // typespec-ts tests use chai-style assertions (`expect(x).to.match(...)`), which oxlint's
+      // vitest plugin misreads as an unknown expect modifier.
+      files: ["**/packages/typespec-ts/**/*.test.ts"],
+      plugins: ["vitest"],
+      rules: {
+        "vitest/valid-expect": "off",
+      },
+    },
+    // Type-aware rules (no-floating-promises, no-deprecated) shared from core. They only run when
+    // oxlint is invoked with `--type-aware`. typespec-ts is excluded at the CLI level in the root
+    // `lint` script (its tsconfig is not tsgo-compatible and type-checking it OOMs).
+    typeAwareOverride,
+  ],
+});

package.json

@@ -21,9 +21,10 @@
     "format:dir": "prettier --write",
     "format:extra": "pnpm run-all format:extra",
     "format:extra:check": "pnpm run-all format:extra:check",
-    "lint": "eslint . --max-warnings=0",
+    "lint": "oxlint . --deny-warnings && oxlint packages --type-aware --deny-warnings --ignore-pattern \"packages/typespec-ts/**\"",
+    "lint:ci": "oxlint . --format=unix --deny-warnings && oxlint packages --format=unix --type-aware --deny-warnings --ignore-pattern \"packages/typespec-ts/**\"",
     "lint:extra": "pnpm run-all lint:extra",
-    "lint:fix": "eslint . --fix",
+    "lint:fix": "oxlint . --fix",
     "pack:all": "chronus pack --pack-destination ./temp/artifacts",
     "preinstall": "npx only-allow pnpm",
     "prepare-publish": "node ./eng/scripts/prepare-publish.js",
@@ -47,15 +48,12 @@
   "devDependencies": {
     "@chronus/chronus": "catalog:",
     "@chronus/github": "catalog:",
-    "@eslint/js": "catalog:",
     "@pnpm/workspace.find-packages": "catalog:",
     "@types/node": "catalog:",
     "@vitest/coverage-v8": "catalog:",
-    "@vitest/eslint-plugin": "catalog:",
     "cspell": "catalog:",
-    "eslint": "catalog:",
-    "eslint-plugin-import": "catalog:",
-    "eslint-plugin-unicorn": "catalog:",
+    "oxlint": "catalog:",
+    "oxlint-tsgolint": "catalog:",
     "playwright": "catalog:",
     "prettier": "catalog:",
     "prettier-plugin-astro": "catalog:",
@@ -65,7 +63,6 @@
     "tsx": "catalog:",
     "turbo": "catalog:",
     "typescript": "catalog:",
-    "typescript-eslint": "catalog:",
     "vitest": "catalog:"
   },
   "dependencies": {

packages/typespec-autorest-canonical/package.json

@@ -42,8 +42,8 @@
     "test:watch": "vitest -w",
     "test:ui": "vitest --ui",
     "test:ci": "vitest run --coverage  --reporter=junit --reporter=default",
-    "lint": "eslint .  --max-warnings=0",
-    "lint:fix": "eslint . --fix ",
+    "lint": "oxlint . --deny-warnings",
+    "lint:fix": "oxlint . --fix",
     "regen-docs": "tspd doc .  --enable-experimental  --output-dir ../../website/src/content/docs/docs/emitters/typespec-autorest-canonical/reference"
   },
   "files": [

packages/typespec-autorest/package.json

@@ -45,8 +45,8 @@
     "test:watch": "vitest -w",
     "test:ui": "vitest --ui",
     "test:ci": "vitest run --coverage --reporter=junit --reporter=default",
-    "lint": "eslint .  --max-warnings=0",
-    "lint:fix": "eslint . --fix ",
+    "lint": "oxlint . --deny-warnings",
+    "lint:fix": "oxlint . --fix",
     "regen-docs": "tspd doc .  --enable-experimental  --output-dir ../../website/src/content/docs/docs/emitters/typespec-autorest/reference"
   },
   "files": [

packages/typespec-azure-core/package.json

@@ -51,8 +51,8 @@
     "test:watch": "vitest -w",
     "test:ui": "vitest --ui",
     "test:ci": "vitest run --coverage  --reporter=junit --reporter=default",
-    "lint": "eslint .  --max-warnings=0",
-    "lint:fix": "eslint . --fix ",
+    "lint": "oxlint . --deny-warnings",
+    "lint:fix": "oxlint . --fix",
     "regen-docs": "tspd doc .  --enable-experimental --llmstxt --output-dir ../../website/src/content/docs/docs/libraries/azure-core/reference"
   },
   "files": [

packages/typespec-azure-playground-website/package.json

@@ -43,8 +43,8 @@
     "watch": "vite --port 5174",
     "test:e2e": "cross-env PW_EXPERIMENTAL_TS_ESM=1 playwright test -c e2e",
     "test:e2e:headed": "cross-env PW_EXPERIMENTAL_TS_ESM=1 playwright test -c e2e --headed",
-    "lint": "eslint .  --max-warnings=0",
-    "lint:fix": "eslint . --fix "
+    "lint": "oxlint . --deny-warnings",
+    "lint:fix": "oxlint . --fix"
   },
   "files": [
     "lib/*.tsp",

packages/typespec-azure-portal-core/package.json

@@ -15,8 +15,8 @@
     "test:watch": "vitest -w",
     "test:ui": "vitest --ui",
     "test:ci": "vitest run --coverage  --reporter=junit --reporter=default",
-    "lint": "eslint .  --max-warnings=0",
-    "lint:fix": "eslint . --fix ",
+    "lint": "oxlint . --deny-warnings",
+    "lint:fix": "oxlint . --fix",
     "regen-docs": "tspd doc .  --enable-experimental  --output-dir ../../website/src/content/docs/docs/libraries/azure-portal-core/reference"
   },
   "keywords": [

packages/typespec-azure-resource-manager/package.json

@@ -47,8 +47,8 @@
     "test:watch": "vitest -w",
     "test:ui": "vitest --ui",
     "test:ci": "vitest run --coverage  --reporter=junit --reporter=default",
-    "lint": "eslint .  --max-warnings=0",
-    "lint:fix": "eslint . --fix ",
+    "lint": "oxlint . --deny-warnings",
+    "lint:fix": "oxlint . --fix",
     "regen-docs": "tspd doc .  --enable-experimental --llmstxt  --output-dir ../../website/src/content/docs/docs/libraries/azure-resource-manager/reference"
   },
   "files": [

packages/typespec-azure-rulesets/package.json

@@ -36,8 +36,8 @@
     "test:watch": "vitest -w",
     "test:ui": "vitest --ui",
     "test:ci": "vitest run --coverage --reporter=junit --reporter=default",
-    "lint": "eslint .  --max-warnings=0",
-    "lint:fix": "eslint . --fix ",
+    "lint": "oxlint . --deny-warnings",
+    "lint:fix": "oxlint . --fix",
     "regen-docs": "tspd doc .  --enable-experimental  --output-dir ../../website/src/content/docs/docs/emitters/typespec-azure-rulesets/reference"
   },
   "files": [

packages/typespec-client-generator-core/package.json

@@ -45,8 +45,8 @@
     "test:watch": "vitest -w",
     "test:ui": "vitest --ui",
     "test:ci": "vitest run --coverage  --reporter=junit --reporter=default",
-    "lint": "eslint .  --max-warnings=0",
-    "lint:fix": "eslint . --fix ",
+    "lint": "oxlint . --deny-warnings",
+    "lint:fix": "oxlint . --fix",
     "regen-docs": "tspd doc .  --enable-experimental --llmstxt --output-dir ../../website/src/content/docs/docs/libraries/typespec-client-generator-core/reference"
   },
   "files": [

packages/typespec-metadata/package.json

@@ -36,8 +36,8 @@
     "build": "tsc -p tsconfig.build.json",
     "watch": "tsc -p tsconfig.build.json --watch",
     "clean": "rimraf ./dist ./temp",
-    "lint": "eslint .  --max-warnings=0",
-    "lint:fix": "eslint . --fix ",
+    "lint": "oxlint . --deny-warnings",
+    "lint:fix": "oxlint . --fix",
     "test": "vitest run",
     "test:watch": "vitest -w",
     "test:ui": "vitest --ui",

packages/typespec-ts/package.json

@@ -20,8 +20,8 @@
     "clean": "rimraf ./dist ./typespec-output",
     "build": "tsc -p .",
     "test": "npm run test-next && npm run unit-test && npm run integration-test-ci",
-    "lint": "eslint . --ext .ts --max-warnings=0",
-    "lint:fix": "eslint . --fix --ext .ts",
+    "lint": "oxlint . --deny-warnings",
+    "lint:fix": "oxlint . --fix",
     "check:tree": "node ./test/commands/check-clean-tree.ts",
     "integration-test-ci": "npm run copy:typespec && npm run spector-test",
     "spector-test": "concurrently --kill-others --success first \"npm:start-test-server\" \"npm:generate-and-run\"",