fix: resolve build cloudflare in react 19

src/dev.ts

@@ -6,6 +6,7 @@ import bunAdapter from "@hono/vite-dev-server/bun";
 import nodeAdapter from "@hono/vite-dev-server/node";
 import type { Config as ReactRouterConfig } from "@react-router/dev/config";
 import type { Plugin, UserConfig } from "vite";
+import { getReactVersion } from "./helpers";
 import type { Runtime } from "./types/runtime";
 
 type MetaEnv<T> = {
@@ -77,7 +78,7 @@ export function reactRouterHonoServer(options: ReactRouterHonoServerPluginOption
         `;
       }
     },
-    config(config) {
+    async config(config) {
       pluginConfig = resolvePluginConfig(config, options);
 
       if (!pluginConfig) {
@@ -120,15 +121,20 @@ export function reactRouterHonoServer(options: ReactRouterHonoServerPluginOption
         reactRouterBuildFile = "assets/server-build.js";
       }
 
+      let alias = undefined;
+
+      if (runtime === "cloudflare") {
+        const reactVersion = await getReactVersion();
+
+        alias = {
+          "react-dom/server": reactVersion >= 19 ? "react-dom/server.edge" : "react-dom/server.browser",
+        };
+      }
+
       return {
         ...baseConfig,
         resolve: {
-          alias:
-            runtime === "cloudflare"
-              ? {
-                  "react-dom/server": "react-dom/server.browser",
-                }
-              : undefined,
+          alias,
         },
         build: {
           // https://vite.dev/config/build-options#build-target

src/helpers.ts

@@ -166,3 +166,11 @@ export async function importBuild(): Promise<ServerBuild> {
 export function createGetLoadContext(getLoadContext: HonoServerOptionsBase<Env>["getLoadContext"]) {
   return getLoadContext;
 }
+
+/**
+ * Retrieves the major React version from node_modules
+ */
+export async function getReactVersion() {
+  const reactVersion = await import("react");
+  return Number.parseInt(reactVersion?.version.split(".")[0]);
+}