From c976f5dbb2bbd5dde2a9dcc24b5111019639d1bc Mon Sep 17 00:00:00 2001
From: Ethan Arrowood <ethan@arrowood.dev>
Date: Wed, 6 May 2026 08:58:28 -0600
Subject: [PATCH] feat: add v14 turbopack guard and validate all versions

Next.js v14 does not support turbopack via the createServer or
nextBuild APIs. Log an error and fall back to webpack if a user
sets `bundler: turbopack` with a v14 application.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
---
 src/plugin.ts | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/src/plugin.ts b/src/plugin.ts
index 283ab3a..fad6802 100644
--- a/src/plugin.ts
+++ b/src/plugin.ts
@@ -197,6 +197,11 @@ export async function handleApplication(scope: Scope) {
 		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) {