Move ssrExternals into config directory

Author: markdalgleish

packages/react-router-dev/config/config.ts

@@ -22,7 +22,6 @@ import {
   configRoutesToRouteManifest,
 } from "./routes";
 import { detectPackageManager } from "../cli/detectPackageManager";
-import { ssrExternals } from "../vite/ssr-externals";
 
 const excludedConfigPresetKeys = ["presets"] as const satisfies ReadonlyArray<
   keyof ReactRouterConfig
@@ -702,6 +701,34 @@ export async function resolveEntryFiles({
   return { entryClientFilePath, entryServerFilePath };
 }
 
+export const ssrExternals = isInReactRouterMonorepo()
+  ? [
+      // This is only needed within this repo because these packages
+      // are linked to a directory outside of node_modules so Vite
+      // treats them as internal code by default.
+      "react-router",
+      "react-router-dom",
+      "@react-router/architect",
+      "@react-router/cloudflare",
+      "@react-router/dev",
+      "@react-router/express",
+      "@react-router/node",
+      "@react-router/serve",
+    ]
+  : undefined;
+
+function isInReactRouterMonorepo() {
+  // We use '@react-router/node' for this check since it's a
+  // dependency of this package and guaranteed to be in node_modules
+  let serverRuntimePath = path.dirname(
+    require.resolve("@react-router/node/package.json")
+  );
+  let serverRuntimeParentDir = path.basename(
+    path.resolve(serverRuntimePath, "..")
+  );
+  return serverRuntimeParentDir === "packages";
+}
+
 const entryExts = [".js", ".jsx", ".ts", ".tsx"];
 
 function findEntry(

packages/react-router-dev/vite/plugin.ts

@@ -39,8 +39,8 @@ import {
   type ResolvedReactRouterConfig,
   createConfigLoader,
   resolveEntryFiles,
+  ssrExternals,
 } from "../config/config";
-import { ssrExternals } from "./ssr-externals";
 import * as WithProps from "./with-props";
 
 export async function resolveViteConfig({