FP104: keep Pages Router app paths outside App Router rules

.changeset/fp104-next-pages-app-path.md

@@ -0,0 +1,7 @@
+---
+"react-doctor": patch
+"oxlint-plugin-react-doctor": patch
+"eslint-plugin-react-doctor": patch
+---
+
+Restrict App Router path checks to the project app or src/app directory so nested Pages Router paths do not trigger App Router rules.

packages/fuzz/corpus/regressions/nextjs-no-head-import--pages-app-path.tsx

@@ -0,0 +1,6 @@
+import Head from "next/head";
+export default () => (
+  <Head>
+    <title>Page title</title>
+  </Head>
+);

packages/oxlint-plugin-react-doctor/src/plugin/rules/nextjs/nextjs-no-head-import.regressions.test.ts

@@ -55,3 +55,32 @@ describe("nextjs/nextjs-no-head-import — regressions", () => {
     expect(result.diagnostics.length).toBeGreaterThan(0);
   });
 });
+
+describe("App Router project-relative boundary", () => {
+  it.each([
+    "pages/app/md.tsx",
+    "src/pages/app/index.tsx",
+    "components/app/head.tsx",
+    "lib/app/view.tsx",
+  ])("keeps next/head valid outside the App Router: %s", (relativePath) => {
+    expect(
+      runRule(nextjsNoHeadImport, HEAD_IMPORT_SOURCE, {
+        filename: `/project/${relativePath}`,
+        settings: { "react-doctor": { rootDirectory: "/project" } },
+      }).diagnostics,
+    ).toHaveLength(0);
+  });
+  it.each([
+    "app/page.tsx",
+    "src/app/page.tsx",
+    "app/pages/app/page.tsx",
+    "src/app/(site)/page.tsx",
+  ])("retains App Router reports: %s", (relativePath) => {
+    expect(
+      runRule(nextjsNoHeadImport, HEAD_IMPORT_SOURCE, {
+        filename: `/project/${relativePath}`,
+        settings: { "react-doctor": { rootDirectory: "/project" } },
+      }).diagnostics,
+    ).toHaveLength(1);
+  });
+});

packages/oxlint-plugin-react-doctor/src/plugin/utils/is-in-project-directory.ts

@@ -21,6 +21,9 @@ export const isInProjectDirectory = (
   const rootDirectory = getReactDoctorStringSetting(context.settings, "rootDirectory");
   const relativeFilename = getProjectRelativeFilename(filename, rootDirectory);
   if (relativeFilename !== filename) {
+    if (directoryPath === "app") {
+      return relativeFilename.startsWith("app/") || relativeFilename.startsWith("src/app/");
+    }
     return (
       relativeFilename.startsWith(`${directoryPath}/`) ||
       relativeFilename.includes(directorySegment)

packages/oxlint-plugin-react-doctor/src/plugin/utils/wrap-nextjs-rule.test.ts

@@ -3,19 +3,9 @@ import os from "node:os";
 import * as path from "node:path";
 import { afterEach, beforeEach, describe, expect, it } from "vite-plus/test";
 import { runRule } from "../../test-utils/run-rule.js";
-import { nextjsNoHeadImport } from "../rules/nextjs/nextjs-no-head-import.js";
 import { wrapNextjsRule } from "./wrap-nextjs-rule.js";
 import type { Rule } from "./rule.js";
 
-const wrappedNoHeadImport = wrapNextjsRule(nextjsNoHeadImport);
-
-const headImportCode = `import Head from "next/head";
-
-export default function Page() {
-  return <Head><title>Title</title></Head>;
-}
-`;
-
 const probeRule: Rule = {
   id: "nextjs-gate-probe",
   severity: "warn",
@@ -32,7 +22,7 @@ describe("wrap-nextjs-rule", () => {
   let temporaryDirectory = "";
 
   beforeEach(() => {
-    temporaryDirectory = fs.mkdtempSync(path.join(os.tmpdir(), "rd-nextjs-gate-"));
+    temporaryDirectory = fs.realpathSync(fs.mkdtempSync(path.join(os.tmpdir(), "rd-nextjs-gate-")));
   });
 
   afterEach(() => {
@@ -50,7 +40,7 @@ describe("wrap-nextjs-rule", () => {
   });
 
   it("fires in a package that declares next in dependencies", () => {
-    const result = runRule(wrappedNoHeadImport, headImportCode, {
+    const result = runRule(wrappedProbe, "export {};", {
       filename: createPackageFilename({ dependencies: { next: "15.0.0" } }),
       settings: rootDirectorySettings(),
     });
@@ -60,7 +50,7 @@ describe("wrap-nextjs-rule", () => {
   });
 
   it("fires when next is only a devDependency", () => {
-    const result = runRule(wrappedNoHeadImport, headImportCode, {
+    const result = runRule(wrappedProbe, "export {};", {
       filename: createPackageFilename({ devDependencies: { next: "15.0.0" } }),
       settings: rootDirectorySettings(),
     });
@@ -70,7 +60,7 @@ describe("wrap-nextjs-rule", () => {
   });
 
   it("stays silent in a nested workspace package that never depends on next", () => {
-    const result = runRule(wrappedNoHeadImport, headImportCode, {
+    const result = runRule(wrappedProbe, "export {};", {
       filename: createPackageFilename({ dependencies: { react: "19.0.0", vite: "6.0.0" } }),
       settings: rootDirectorySettings(),
     });
@@ -80,7 +70,7 @@ describe("wrap-nextjs-rule", () => {
   });
 
   it("fires in a non-next package when no project root is provided", () => {
-    const result = runRule(wrappedNoHeadImport, headImportCode, {
+    const result = runRule(wrappedProbe, "export {};", {
       filename: createPackageFilename({ dependencies: { react: "19.0.0" } }),
     });
 
@@ -89,7 +79,7 @@ describe("wrap-nextjs-rule", () => {
   });
 
   it("fires below the root when the nearest manifest is a marker without dependencies", () => {
-    const result = runRule(wrappedNoHeadImport, headImportCode, {
+    const result = runRule(wrappedProbe, "export {};", {
       filename: createPackageFilename({ type: "module" }),
       settings: rootDirectorySettings(),
     });
@@ -99,7 +89,7 @@ describe("wrap-nextjs-rule", () => {
   });
 
   it("fires when there is no discoverable package manifest", () => {
-    const result = runRule(wrappedNoHeadImport, headImportCode, {
+    const result = runRule(wrappedProbe, "export {};", {
       filename: path.join(temporaryDirectory, "standalone", "app", "page.tsx"),
       settings: rootDirectorySettings(),
     });