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Merged
Ethan-Arrowood merged 2 commits into from
May 6, 2026
Merged

feat: add turbopack support for Next.js v15 #44

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7373157
feat: add turbopack support for Next.js v15 and refactor bundler option
Ethan-Arrowood May 6, 2026
32e4f5e
feat: add v14 turbopack guard and validate all versions (#45)
Ethan-Arrowood May 6, 2026
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1 change: 1 addition & 0 deletions fixtures/next-15-turbopack/.npmrc
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@@ -0,0 +1 @@
package-lock=false
11 changes: 11 additions & 0 deletions fixtures/next-15-turbopack/app/layout.js
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@@ -0,0 +1,11 @@
export const metadata = {
title: 'Harper - Next.js v15 App',
};

export default function RootLayout({ children }) {
return (
<html>
<body>{children}</body>
</html>
);
}
7 changes: 7 additions & 0 deletions fixtures/next-15-turbopack/app/page.js
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@@ -0,0 +1,7 @@
export default async function Page() {
return (
<div>
<h1>Next.js v15</h1>
</div>
);
}
3 changes: 3 additions & 0 deletions fixtures/next-15-turbopack/config.yaml
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'@harperfast/nextjs':
package: '@harperfast/nextjs'
bundler: turbopack
3 changes: 3 additions & 0 deletions fixtures/next-15-turbopack/next.config.mjs
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import { withHarper } from '@harperfast/nextjs';

export default withHarper({});
16 changes: 16 additions & 0 deletions fixtures/next-15-turbopack/package.json
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{
"name": "next-15",
"private": true,
"scripts": {
"dev": "next dev",
"build": "next build",
"start": "next start",
"lint": "next lint"
},
"dependencies": {
"@harperfast/nextjs": "file:../../",
"react": "^19",
"react-dom": "^19",
"next": "^15"
}
}
2 changes: 1 addition & 1 deletion fixtures/next-16-webpack/config.yaml
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@@ -1,3 +1,3 @@
'@harperfast/nextjs':
package: '@harperfast/nextjs'
webpack: true
bundler: webpack
18 changes: 18 additions & 0 deletions integrationTests/next-15-turbopack.pw.ts
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import { fixture } from './fixture.ts';

const { test, expect } = fixture('next-15-turbopack');

test('home page renders', async ({ page, harper }) => {
await page.goto(harper.httpURL);
await expect(page.locator('h1')).toHaveText('Next.js v15');
});

test('page title is set', async ({ page, harper }) => {
await page.goto(harper.httpURL);
await expect(page).toHaveTitle('Harper - Next.js v15 App');
});

test('status endpoint returns 200', async ({ request, harper }) => {
const response = await request.get(`${harper.operationsAPIURL}/health`);
expect(response.status()).toBe(200);
});
32 changes: 25 additions & 7 deletions src/plugin.ts
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Expand Up @@ -14,16 +14,18 @@ import type NextBuildModule15 from 'next-15/dist/cli/next-build.d.ts';
import type NextModule16 from 'next-16';
import type NextBuildModule16 from 'next-16/dist/cli/next-build.d.ts';

type Bundler = 'webpack' | 'turbopack';

interface NextPluginConfig extends Config {
buildOnly: boolean;
bundler: Bundler;
dev: boolean;
// @ts-expect-error
files?: FilesOption;
port?: number;
prebuilt: boolean;
runFirst: boolean;
securePort?: number;
webpack: boolean;
}

// Bringing this forward from extension since some validation is better than none.
Expand Down Expand Up @@ -64,24 +66,29 @@ function resolveConfig(scope: Scope): NextPluginConfig {
}

assertType('buildOnly', options.buildOnly, 'boolean');
assertType('bundler', options.bundler, 'string');
assertType('dev', options.dev, 'boolean');
assertType('port', options.port, 'number');
assertType('prebuilt', options.prebuilt, 'boolean');
assertType('runFirst', options.runFirst, 'boolean');
assertType('securePort', options.securePort, 'number');
assertType('webpack', options.webpack, 'boolean');

if (options.bundler && options.bundler !== 'webpack' && options.bundler !== 'turbopack') {
throw new Error(`bundler must be "webpack" or "turbopack". Received: "${options.bundler}"`);
}

// TODO: Remove type casts when we have more proper plugin option validation from core
return {
buildOnly: (options.buildOnly as boolean) ?? false,
// bundler default is set later in handleApplication() based on the detected Next.js version
bundler: options.bundler as Bundler,
dev: (options.dev as boolean) ?? false,
// @ts-expect-error
files: options.files,
port: options.port as number,
prebuilt: (options.prebuilt as boolean) ?? false,
runFirst: (options.runFirst as boolean) ?? false,
securePort: options.securePort as number,
webpack: (options.webpack as boolean) ?? false,
} satisfies NextPluginConfig;
}

Expand Down Expand Up @@ -184,6 +191,17 @@ export async function handleApplication(scope: Scope) {

const next = importNext(scope);

// Set the bundler default based on the detected Next.js version if not explicitly configured.
// Next.js v16 defaults to turbopack; v14 and v15 default to webpack.
if (!config.bundler) {
config.bundler = next.version >= 16 ? 'turbopack' : 'webpack';
}

if (config.bundler === 'turbopack' && next.version === 14) {
scope.logger.error?.('Turbopack is not supported for Next.js v14. Falling back to webpack.');
config.bundler = 'webpack';
}

scope.logger.debug?.(`Detected Next.js version: ${next.version}`);

if (config.prebuilt) {
Expand Down Expand Up @@ -297,7 +315,7 @@ async function build(scope: Scope, config: NextPluginConfig, next: NextPackage)
{
lint: false,
mangling: true,
turbopack: false,
...(config.bundler === 'turbopack' && { turbopack: true }),
experimentalDebugMemoryUsage: false,
experimentalBuildMode: 'default',
},
Expand All @@ -308,7 +326,7 @@ async function build(scope: Scope, config: NextPluginConfig, next: NextPackage)
await next.build(
{
mangling: true,
webpack: config.webpack,
...(config.bundler === 'webpack' && { webpack: true }),
experimentalDebugMemoryUsage: false,
experimentalBuildMode: 'default',
},
Expand Down Expand Up @@ -341,10 +359,10 @@ async function serve(scope: Scope, config: NextPluginConfig, next: NextPackage)
app = next.server({ dir: scope.directory, dev: config.dev });
break;
case 15:
app = next.server({ dir: scope.directory, dev: config.dev, turbopack: false });
app = next.server({ dir: scope.directory, dev: config.dev, ...(config.bundler === 'turbopack' && { turbopack: true }) });
break;
case 16:
app = next.server({ dir: scope.directory, dev: config.dev, ...(config.webpack && { webpack: true }) });
app = next.server({ dir: scope.directory, dev: config.dev, ...(config.bundler === 'webpack' && { webpack: true }) });
break;
}

Expand Down
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