fix(module-runner): make getBuiltins response JSON serializable

packages/vite/src/module-runner/runner.ts

@@ -247,7 +247,18 @@ export class ModuleRunner {
     this.builtinsPromise ??= (async () => {
       try {
         this.debug?.('[module runner] fetching builtins from server')
-        const builtins = await this.transport.invoke('getBuiltins', [])
+        const serializedBuiltins = await this.transport.invoke(
+          'getBuiltins',
+          [],
+        )
+        const builtins = serializedBuiltins.map((builtin) =>
+          typeof builtin === 'object' && builtin && 'type' in builtin
+            ? builtin.type === 'string'
+              ? builtin.value
+              : new RegExp(builtin.source, builtin.flags)
+            : // NOTE: Vitest returns raw values instead of serialized ones
+              builtin,
+        )
         this.isBuiltin = createIsBuiltin(builtins)
         this.debug?.('[module runner] builtins loaded:', builtins)
       } finally {

packages/vite/src/node/server/environment.ts

@@ -134,7 +134,11 @@ export class DevEnvironment extends BaseEnvironment {
         return this.fetchModule(id, importer, options)
       },
       getBuiltins: async () => {
-        return this.config.resolve.builtins
+        return this.config.resolve.builtins.map((builtin) =>
+          typeof builtin === 'string'
+            ? { type: 'string', value: builtin }
+            : { type: 'RegExp', source: builtin.source, flags: builtin.flags },
+        )
       },
     })
 

packages/vite/src/shared/invokeMethods.ts

@@ -83,5 +83,10 @@ export type InvokeMethods = {
     options?: FetchFunctionOptions,
   ) => Promise<FetchResult>
 
-  getBuiltins: () => Promise<(string | RegExp)[]>
+  getBuiltins: () => Promise<
+    Array<
+      | { type: 'string'; value: string }
+      | { type: 'RegExp'; source: string; flags: string }
+    >
+  >
 }