fix(core): preserve settings from adopted lint configs

.changeset/adopt-tailwind-settings.md

@@ -0,0 +1,6 @@
+---
+"@react-doctor/core": patch
+"react-doctor": patch
+---
+
+Preserve plugin settings when React Doctor adopts an existing lint config.

packages/core/src/can-oxlint-extend-config.ts

@@ -1,4 +1,5 @@
 import * as fs from "node:fs";
+import { parseJSONC } from "confbox";
 import { isPlainObject } from "./project-info/index.js";
 
 const EXTENDS_LOCAL_PATH_PREFIXES = ["./", "../", "/"];
@@ -10,61 +11,6 @@ const isLocalPathExtend = (entry: string): boolean => {
   return false;
 };
 
-// HACK: ESLint's JSON config files in the wild are routinely JSONC —
-// `//` line comments and `/* */` block comments. Strict `JSON.parse`
-// throws on them. Strip both forms (avoiding matches inside string
-// literals) so the extends pre-screen still works on real Next.js /
-// CRA / TypeScript scaffolds.
-const stripJsoncComments = (raw: string): string => {
-  let result = "";
-  let cursor = 0;
-  let inString = false;
-  let stringQuote = "";
-  while (cursor < raw.length) {
-    const character = raw[cursor];
-    const nextCharacter = raw[cursor + 1];
-    if (inString) {
-      result += character;
-      if (character === "\\" && cursor + 1 < raw.length) {
-        result += nextCharacter;
-        cursor += 2;
-        continue;
-      }
-      if (character === stringQuote) inString = false;
-      cursor += 1;
-      continue;
-    }
-    if (character === '"' || character === "'") {
-      inString = true;
-      stringQuote = character;
-      result += character;
-      cursor += 1;
-      continue;
-    }
-    if (character === "/" && nextCharacter === "/") {
-      const lineEndIndex = raw.indexOf("\n", cursor);
-      cursor = lineEndIndex === -1 ? raw.length : lineEndIndex;
-      continue;
-    }
-    if (character === "/" && nextCharacter === "*") {
-      const blockEndIndex = raw.indexOf("*/", cursor + 2);
-      cursor = blockEndIndex === -1 ? raw.length : blockEndIndex + 2;
-      continue;
-    }
-    result += character;
-    cursor += 1;
-  }
-  return result;
-};
-
-const parseJsonOrJsonc = (raw: string): unknown => {
-  try {
-    return JSON.parse(raw);
-  } catch {
-    return JSON.parse(stripJsoncComments(raw));
-  }
-};
-
 // HACK: oxlint's `extends` resolver only handles local file paths and
 // other oxlint configs — bare-package extends (`"next"`, `"airbnb"`,
 // `"plugin:@typescript-eslint/recommended"`) crash the parser with
@@ -83,7 +29,7 @@ export const canOxlintExtendConfig = (configPath: string): boolean => {
   let parsed: unknown;
   try {
     const raw = fs.readFileSync(configPath, "utf-8");
-    parsed = parseJsonOrJsonc(raw);
+    parsed = parseJSONC<unknown>(raw, { allowTrailingComma: true });
   } catch {
     return true;
   }

packages/core/src/read-adopted-lint-config-settings.ts

@@ -0,0 +1,35 @@
+import * as fs from "node:fs";
+import { parseJSONC } from "confbox";
+import { isPlainObject } from "./project-info/index.js";
+
+export interface AdoptedLintConfigSettings {
+  readonly [pluginName: string]: unknown;
+}
+
+export const readAdoptedLintConfigSettings = (
+  configPaths: ReadonlyArray<string>,
+): AdoptedLintConfigSettings => {
+  const mergedSettings = new Map<string, unknown>();
+
+  for (const configPath of configPaths) {
+    let parsed: unknown;
+    try {
+      const raw = fs.readFileSync(configPath, "utf-8");
+      parsed = parseJSONC<unknown>(raw, { allowTrailingComma: true });
+    } catch {
+      continue;
+    }
+
+    if (!isPlainObject(parsed)) continue;
+
+    const settings = parsed.settings;
+    if (!isPlainObject(settings)) continue;
+
+    for (const [pluginName, pluginSettings] of Object.entries(settings)) {
+      if (pluginName === "react-doctor") continue;
+      mergedSettings.set(pluginName, pluginSettings);
+    }
+  }
+
+  return Object.fromEntries(mergedSettings);
+};

packages/core/src/run-oxlint.ts

@@ -14,6 +14,7 @@ import { buildRuleSeverityControls } from "./build-rule-severity-controls.js";
 import { canOxlintExtendConfig } from "./can-oxlint-extend-config.js";
 import { collectIgnorePatterns } from "./collect-ignore-patterns.js";
 import { detectUserLintConfigPaths } from "./detect-user-lint-config.js";
+import { readAdoptedLintConfigSettings } from "./read-adopted-lint-config-settings.js";
 import { ReactDoctorError } from "./errors.js";
 import { neutralizeDisableDirectives } from "./neutralize-disable-directives.js";
 import { computeRulesetHash } from "./runners/oxlint/compute-ruleset-hash.js";
@@ -328,6 +329,8 @@ export const runOxlint = async (options: RunOxlintOptions): Promise<Diagnostic[]
   // the parser crash + misleading warning. Drop them up front so the
   // scan starts in the same state the fallback would land in.
   const extendsPaths = detectedConfigPaths.filter(canOxlintExtendConfig);
+  const adoptedSettings =
+    detectedConfigPaths.length > 0 ? readAdoptedLintConfigSettings(detectedConfigPaths) : {};
   const userPlugins =
     includedTags.size > 0 ? [] : resolveUserPlugins(userConfig?.plugins, configSourceDirectory);
 
@@ -452,6 +455,7 @@ export const runOxlint = async (options: RunOxlintOptions): Promise<Diagnostic[]
         serverAuthFunctionNames,
         projectIndexModuleSources,
         severityControls,
+        adoptedSettings,
         userPlugins,
         disableReactHooksJsPlugin: overrides.disableReactHooksJsPlugin,
         ruleSelection: overrides.ruleSelection,

packages/core/src/runners/oxlint/config.ts

@@ -7,6 +7,7 @@ import {
 } from "oxlint-plugin-react-doctor/core";
 import type { OxlintRuleSeverity } from "oxlint-plugin-react-doctor/core";
 import type { ProjectInfo, RuleSeverityControls } from "../../types/index.js";
+import type { AdoptedLintConfigSettings } from "../../read-adopted-lint-config-settings.js";
 import { resolveRuleSeverityOverride } from "../../resolve-rule-severity-override.js";
 import { COMPILER_CLEANUP_BUCKET, COMPILER_CLEANUP_RULE_KEYS } from "../../constants.js";
 import { getCapabilities, shouldEnableRule } from "../../project-info/capabilities.js";
@@ -28,6 +29,7 @@ export interface OxlintConfigOptions {
   serverAuthFunctionNames?: ReadonlyArray<string>;
   projectIndexModuleSources?: ReadonlyArray<string>;
   severityControls?: RuleSeverityControls;
+  adoptedSettings?: AdoptedLintConfigSettings;
   /**
    * User-declared plugins from `react-doctor.config.json`'s
    * `plugins: [...]`, already resolved + introspected via
@@ -134,6 +136,7 @@ export const createOxlintConfig = ({
   serverAuthFunctionNames,
   projectIndexModuleSources,
   severityControls,
+  adoptedSettings = {},
   userPlugins = [],
   disableReactHooksJsPlugin = false,
   ruleSelection,
@@ -281,6 +284,7 @@ export const createOxlintConfig = ({
     plugins: [],
     jsPlugins: [...jsPlugins, pluginPath],
     settings: {
+      ...adoptedSettings,
       "react-doctor": {
         portedRuleMode: "curated",
         framework: project.framework,

packages/core/tests/can-oxlint-extend-config.test.ts

@@ -94,7 +94,7 @@ describe("canOxlintExtendConfig", () => {
   "extends": ["next", "plugin:@typescript-eslint/recommended"],
   "rules": {
     // "off-for-now": "off"
-  }
+  },
 }
 `,
     );

packages/core/tests/fixtures/user-tailwind-config/.oxlintrc.json

@@ -0,0 +1,14 @@
+{
+  "plugins": ["oxlint-plugin-tailwindcss"],
+  "rules": {
+    "tailwindcss/enforce-canonical": "error",
+    "tailwindcss/enforce-sort-order": "error",
+    "tailwindcss/no-conflicting-classes": "error",
+    "tailwindcss/no-unknown-classes": "error"
+  },
+  "settings": {
+    "tailwindcss": {
+      "entryPoint": "src/styles.css"
+    }
+  }
+}

packages/core/tests/fixtures/user-tailwind-config/package.json

@@ -0,0 +1,13 @@
+{
+  "name": "user-tailwind-config",
+  "version": "1.0.0",
+  "private": true,
+  "dependencies": {
+    "react": "^19.0.0",
+    "react-dom": "^19.0.0",
+    "tailwindcss": "^4.0.0"
+  },
+  "devDependencies": {
+    "oxlint-plugin-tailwindcss": "^1.0.0"
+  }
+}

packages/core/tests/fixtures/user-tailwind-config/src/button.tsx

@@ -0,0 +1,5 @@
+import React from "react";
+
+export const Button = () => {
+  return <button className="bg-blue-500 hover:bg-blue-700 text-white">Click me</button>;
+};

packages/core/tests/fixtures/user-tailwind-config/src/styles.css

@@ -0,0 +1,3 @@
+@tailwind base;
+@tailwind components;
+@tailwind utilities;

packages/core/tests/oxlint-config-settings.test.ts

@@ -269,6 +269,31 @@ describe("createOxlintConfig settings", () => {
     });
   });
 
+  it("merges adopted settings without replacing react-doctor settings", () => {
+    const config = createOxlintConfig({
+      pluginPath: "/tmp/plugin.js",
+      project: tailwindViteWebProject,
+      runtimeGlobals: ["DatePicker"],
+      adoptedSettings: {
+        tailwindcss: {
+          entryPoint: "src/styles.css",
+        },
+        "other-plugin": {
+          option: "value",
+        },
+      },
+    });
+
+    expect(config.settings.tailwindcss).toEqual({
+      entryPoint: "src/styles.css",
+    });
+    expect(config.settings["other-plugin"]).toEqual({
+      option: "value",
+    });
+    expect(config.settings["react-doctor"].framework).toBe("vite");
+    expect(config.settings["react-doctor"].runtimeGlobals).toEqual(["DatePicker"]);
+  });
+
   it("never registers security scan rules (they run as a core environment check)", () => {
     const config = createOxlintConfig({
       pluginPath: "/tmp/plugin.js",

packages/core/tests/read-adopted-lint-config-settings.test.ts

@@ -0,0 +1,106 @@
+import * as fs from "node:fs";
+import * as os from "node:os";
+import * as path from "node:path";
+import { afterEach, beforeEach, describe, expect, it } from "vite-plus/test";
+import { canOxlintExtendConfig } from "../src/can-oxlint-extend-config.js";
+import { readAdoptedLintConfigSettings } from "../src/read-adopted-lint-config-settings.js";
+
+describe("readAdoptedLintConfigSettings", () => {
+  let temporaryDirectory: string;
+
+  beforeEach(() => {
+    temporaryDirectory = fs.mkdtempSync(path.join(os.tmpdir(), "react-doctor-settings-"));
+  });
+
+  afterEach(() => {
+    fs.rmSync(temporaryDirectory, { recursive: true, force: true });
+  });
+
+  const writeConfig = (filename: string, content: string): string => {
+    const configPath = path.join(temporaryDirectory, filename);
+    fs.writeFileSync(configPath, content);
+    return configPath;
+  };
+
+  it("reads JSONC settings and skips react-doctor settings", () => {
+    const configPath = writeConfig(
+      ".oxlintrc.json",
+      `{
+        // Keep the Tailwind source path.
+        "settings": {
+          "react-doctor": { "framework": "next" },
+          "tailwindcss": { "entryPoint": "src/styles.css" },
+        },
+      }`,
+    );
+
+    expect(readAdoptedLintConfigSettings([configPath])).toEqual({
+      tailwindcss: { entryPoint: "src/styles.css" },
+    });
+  });
+
+  it("reads settings from an ESLint config that Oxlint cannot extend", () => {
+    const configPath = writeConfig(
+      ".eslintrc.json",
+      JSON.stringify({
+        extends: ["next/core-web-vitals"],
+        settings: { tailwindcss: { entryPoint: "src/styles.css" } },
+      }),
+    );
+
+    expect(canOxlintExtendConfig(configPath)).toBe(false);
+    expect(readAdoptedLintConfigSettings([configPath])).toEqual({
+      tailwindcss: { entryPoint: "src/styles.css" },
+    });
+  });
+
+  it("uses the last value when configs contain the same setting", () => {
+    const firstConfigPath = writeConfig(
+      "first.json",
+      JSON.stringify({ settings: { tailwindcss: { entryPoint: "first.css" } } }),
+    );
+    const secondConfigPath = writeConfig(
+      "second.json",
+      JSON.stringify({
+        settings: {
+          tailwindcss: { entryPoint: "second.css" },
+          "other-plugin": { option: true },
+        },
+      }),
+    );
+
+    expect(readAdoptedLintConfigSettings([firstConfigPath, secondConfigPath])).toEqual({
+      tailwindcss: { entryPoint: "second.css" },
+      "other-plugin": { option: true },
+    });
+  });
+
+  it("skips missing, invalid, and non-settings configs", () => {
+    const invalidConfigPath = writeConfig("invalid.json", "{ invalid json");
+    const rulesOnlyConfigPath = writeConfig(
+      "rules-only.json",
+      JSON.stringify({ rules: { "no-debugger": "error" } }),
+    );
+
+    expect(
+      readAdoptedLintConfigSettings([
+        path.join(temporaryDirectory, "missing.json"),
+        invalidConfigPath,
+        rulesOnlyConfigPath,
+      ]),
+    ).toEqual({});
+  });
+
+  it("does not allow special keys to change the result prototype", () => {
+    const configPath = writeConfig(
+      ".oxlintrc.json",
+      `{"settings":{"__proto__":{"polluted":true}}}`,
+    );
+
+    const settings = readAdoptedLintConfigSettings([configPath]);
+
+    expect(Object.getPrototypeOf(settings)).toBe(Object.prototype);
+    expect(Object.hasOwn(settings, "__proto__")).toBe(false);
+    expect(Object.prototype).not.toHaveProperty("polluted");
+  });
+});

packages/react-doctor/tests/run-oxlint/_helpers.ts

@@ -22,6 +22,7 @@ export const USER_OXLINT_CONFIG_BROKEN_DIRECTORY = path.join(
   FIXTURES_DIRECTORY,
   "user-oxlint-config-broken",
 );
+export const USER_TAILWIND_CONFIG_DIRECTORY = path.join(FIXTURES_DIRECTORY, "user-tailwind-config");
 
 const findDiagnosticsByRule = (diagnostics: Diagnostic[], rule: string): Diagnostic[] =>
   diagnostics.filter((diagnostic) => diagnostic.rule === rule);