fix(migrate): remove scoped Prettier plugins and shareable configs

packages/cli/src/migration/__tests__/migrator.spec.ts

@@ -49,6 +49,7 @@ const {
   ensureSvelteRuneGlobals,
   mergeViteConfigFiles,
   rewriteEslintPackageJson,
+  rewritePrettierPackageJson,
   collectInstalledPackageNames,
   sanitizeMigratedOxlintConfig,
   detectIncompatibleEslintIntegration,
@@ -1136,6 +1137,123 @@ describe('rewriteEslintPackageJson', () => {
   });
 });
 
+describe('rewritePrettierPackageJson', () => {
+  let tmpDir: string;
+
+  beforeEach(() => {
+    tmpDir = fs.mkdtempSync(path.join(os.tmpdir(), 'vp-test-prettier-cleanup-'));
+  });
+
+  afterEach(() => {
+    fs.rmSync(tmpDir, { recursive: true, force: true });
+  });
+
+  function writePkg(pkg: object): string {
+    const pkgPath = path.join(tmpDir, 'package.json');
+    fs.writeFileSync(pkgPath, JSON.stringify(pkg));
+    return pkgPath;
+  }
+
+  it('removes prettier and flat prettier-plugin-* / prettier-config-* packages', () => {
+    const pkgPath = writePkg({
+      devDependencies: {
+        prettier: '^3.0.0',
+        'prettier-plugin-tailwindcss': '^0.6.0',
+        'prettier-plugin-astro': '^0.14.0',
+        'prettier-config-standard': '^7.0.0',
+        vite: '^7.0.0',
+      },
+      dependencies: {
+        'prettier-plugin-svelte': '^3.0.0',
+        vue: '^3.5.0',
+      },
+    });
+    rewritePrettierPackageJson(pkgPath);
+    const pkg = readJson(pkgPath);
+    expect(pkg.devDependencies).toEqual({ vite: '^7.0.0' });
+    expect(pkg.dependencies).toEqual({ vue: '^3.5.0' });
+  });
+
+  it('removes scoped Prettier plugin/config packages (e.g. @trivago/prettier-plugin-sort-imports)', () => {
+    const pkgPath = writePkg({
+      devDependencies: {
+        '@trivago/prettier-plugin-sort-imports': '^5.0.0',
+        '@ianvs/prettier-plugin-sort-imports': '^4.0.0',
+        '@shopify/prettier-plugin-liquid': '^1.0.0',
+        '@company/prettier-config': '^1.0.0',
+        keepme: '^1.0.0',
+      },
+    });
+    rewritePrettierPackageJson(pkgPath);
+    const pkg = readJson(pkgPath);
+    expect(pkg.devDependencies).toEqual({ keepme: '^1.0.0' });
+  });
+
+  it('removes @prettier/* scope packages', () => {
+    const pkgPath = writePkg({
+      devDependencies: {
+        '@prettier/plugin-php': '^0.22.0',
+        '@prettier/plugin-xml': '^3.0.0',
+        '@prettier/plugin-ruby': '^4.0.0',
+        '@prettier/sync': '^0.5.0',
+        keepme: '^1.0.0',
+      },
+    });
+    rewritePrettierPackageJson(pkgPath);
+    const pkg = readJson(pkgPath);
+    expect(pkg.devDependencies).toEqual({ keepme: '^1.0.0' });
+  });
+
+  it('removes @types/<X> packages symmetrically with their runtime counterparts', () => {
+    const pkgPath = writePkg({
+      devDependencies: {
+        prettier: '^3.0.0',
+        '@types/prettier': '^3.0.0',
+        // Unrelated @types should stay.
+        '@types/node': '^22.0.0',
+      },
+    });
+    rewritePrettierPackageJson(pkgPath);
+    const pkg = readJson(pkgPath);
+    expect(pkg.devDependencies).toEqual({ '@types/node': '^22.0.0' });
+  });
+
+  it('preserves unrelated packages that merely contain "prettier" in their name', () => {
+    const pkgPath = writePkg({
+      devDependencies: {
+        // Not Prettier-only: these are ESLint packages, handled by the
+        // ESLint migration when it runs.
+        'eslint-config-prettier': '^9.0.0',
+        'eslint-plugin-prettier': '^5.0.0',
+        // Not a Prettier plugin: a scope that merely starts with the same
+        // characters, and a flat name that isn't a plugin/config.
+        '@prettierx/core': '^1.0.0',
+        prettierx: '^0.19.0',
+        vite: '^7.0.0',
+      },
+    });
+    rewritePrettierPackageJson(pkgPath);
+    const pkg = readJson(pkgPath);
+    expect(pkg.devDependencies).toEqual({
+      'eslint-config-prettier': '^9.0.0',
+      'eslint-plugin-prettier': '^5.0.0',
+      '@prettierx/core': '^1.0.0',
+      prettierx: '^0.19.0',
+      vite: '^7.0.0',
+    });
+  });
+
+  it('no-ops when package.json has no prettier-ecosystem deps', () => {
+    const pkgPath = writePkg({
+      devDependencies: { vite: '^7.0.0' },
+    });
+    const before = fs.readFileSync(pkgPath, 'utf8');
+    rewritePrettierPackageJson(pkgPath);
+    const after = fs.readFileSync(pkgPath, 'utf8');
+    expect(after).toBe(before);
+  });
+});
+
 describe('collectInstalledPackageNames', () => {
   let tmpDir: string;
 

packages/cli/src/migration/migrator/prettier.ts

@@ -219,7 +219,48 @@ function deletePrettierConfigFiles(
   });
 }
 
-function rewritePrettierPackageJson(packageJsonPath: string): void {
+// Bare names of packages whose sole purpose is to support Prettier.
+const PRETTIER_ECOSYSTEM_NAMES = new Set<string>(['prettier']);
+
+// Flat name prefixes that mark a Prettier-only package.
+const PRETTIER_ECOSYSTEM_PREFIXES = ['prettier-plugin-', 'prettier-config-'];
+
+// Scopes whose every package is part of the Prettier ecosystem.
+//   @prettier/*  — official Prettier scope (@prettier/plugin-php,
+//                  @prettier/plugin-xml, @prettier/plugin-ruby, @prettier/sync)
+const PRETTIER_ECOSYSTEM_SCOPES = ['@prettier/'];
+
+/**
+ * Decide whether a dependency entry should be removed alongside `prettier`
+ * itself, mirroring `isEslintEcosystemDep` in `eslint.ts`. Plugins and
+ * shareable configs are dead weight once formatting moves to Oxfmt, and
+ * scoped names are as common as flat ones — `@trivago/prettier-plugin-sort-imports`
+ * is not less of a Prettier plugin than `prettier-plugin-tailwindcss`.
+ * `@types/<X>` packages are checked symmetrically with `<X>`.
+ */
+function isPrettierEcosystemDep(name: string): boolean {
+  const stripped = name.startsWith('@types/') ? name.slice('@types/'.length) : name;
+  if (PRETTIER_ECOSYSTEM_NAMES.has(stripped)) {
+    return true;
+  }
+  if (PRETTIER_ECOSYSTEM_PREFIXES.some((p) => stripped.startsWith(p))) {
+    return true;
+  }
+  if (PRETTIER_ECOSYSTEM_SCOPES.some((s) => stripped.startsWith(s))) {
+    return true;
+  }
+  // Scoped plugins/configs, e.g.:
+  //   @trivago/prettier-plugin-sort-imports
+  //   @ianvs/prettier-plugin-sort-imports
+  //   @shopify/prettier-plugin-liquid
+  //   @company/prettier-config
+  if (/^@[^/]+\/prettier-(plugin|config)(-.+)?$/.test(stripped)) {
+    return true;
+  }
+  return false;
+}
+
+export function rewritePrettierPackageJson(packageJsonPath: string): void {
   if (!fs.existsSync(packageJsonPath)) {
     return;
   }
@@ -230,18 +271,18 @@ function rewritePrettierPackageJson(packageJsonPath: string): void {
     'lint-staged'?: Record<string, string | string[]>;
   }>(packageJsonPath, (pkg) => {
     let changed = false;
-    // Remove prettier and prettier-plugin-* dependencies
+    // Remove prettier and its plugins / shareable configs
     if (pkg.devDependencies) {
       for (const dep of Object.keys(pkg.devDependencies)) {
-        if (dep === 'prettier' || dep.startsWith('prettier-plugin-')) {
+        if (isPrettierEcosystemDep(dep)) {
           delete pkg.devDependencies[dep];
           changed = true;
         }
       }
     }
     if (pkg.dependencies) {
       for (const dep of Object.keys(pkg.dependencies)) {
-        if (dep === 'prettier' || dep.startsWith('prettier-plugin-')) {
+        if (isPrettierEcosystemDep(dep)) {
           delete pkg.dependencies[dep];
           changed = true;
         }