constant should be constant

devjiwonchoi · devjiwonchoi · commit 9643f90c72bc · 2025-09-12T15:59:25.000+02:00
diff --git a/packages/next/src/server/config.ts b/packages/next/src/server/config.ts
@@ -1380,7 +1380,14 @@ export default async function loadConfig(
     return config
   }
 
-  const path = await findUp(CONFIG_FILES, { cwd: dir })
+  const path = await findUp(
+    CONFIG_FILES.concat(
+      // 'next.config.mts' is only available when Node.js native TypeScript resolution is enabled.
+      // TODO: Remove `as any` once we bump @types/node to v22.10.0+
+      (process.features as any)?.typescript ? ['next.config.mts'] : []
+    ),
+    { cwd: dir }
+  )
 
   // If config file was found
   if (path?.length) {
@@ -1592,7 +1599,6 @@ export default async function loadConfig(
       [
         `${configBaseName}.cjs`,
         `${configBaseName}.cts`,
-        `${configBaseName}.mts`,
         `${configBaseName}.json`,
         `${configBaseName}.jsx`,
         `${configBaseName}.tsx`,
diff --git a/packages/next/src/server/lib/start-server.ts b/packages/next/src/server/lib/start-server.ts
@@ -487,7 +487,11 @@ export async function startServer(
     ) {
       const wp = new Watchpack()
       wp.watch({
-        files: CONFIG_FILES.map((file) => path.join(dirToWatch, file)),
+        files: CONFIG_FILES.concat(
+          // 'next.config.mts' is only available when Node.js native TypeScript resolution is enabled.
+          // TODO: Remove `as any` once we bump @types/node to v22.10.0+
+          (process.features as any)?.typescript ? ['next.config.mts'] : []
+        ).map((file) => path.join(dirToWatch, file)),
       })
       wp.on('change', onChange)
     }
diff --git a/packages/next/src/shared/lib/constants.ts b/packages/next/src/shared/lib/constants.ts
@@ -109,9 +109,6 @@ export const CONFIG_FILES = [
   'next.config.js',
   'next.config.mjs',
   'next.config.ts',
-  // process.features can be undefined on Edge runtime
-  // TODO: Remove `as any` once we bump @types/node to v22.10.0+
-  ...((process?.features as any)?.typescript ? ['next.config.mts'] : []),
 ]
 export const BUILD_ID_FILE = 'BUILD_ID'
 export const BLOCKED_PAGES = ['/_document', '/_app', '/_error']
