Fix response streaming with wrangler dev server (#1242)

Fixes #1237.

examples/07_cloudflare/src/pages/index.tsx

@@ -2,7 +2,7 @@ import { Link } from 'waku';
 import { Suspense } from 'react';
 import { Counter } from '../components/counter';
 import { getHonoContext } from '../lib/hono';
-import { getEnv } from '../lib/waku';
+import { getEnv, isBuild } from '../lib/waku';
 
 export default async function HomePage() {
   const data = await getData();
@@ -44,6 +44,9 @@ export default async function HomePage() {
 
 // Example async server component
 const ServerMessage = async () => {
+  if (isBuild()) {
+    console.warn('Note: server components are awaited during build.');
+  }
   await new Promise((resolve) => setTimeout(resolve, 2000));
   return <p>Hello from server!</p>;
 };

examples/07_cloudflare/waku.cloudflare-middleware.ts

@@ -0,0 +1,30 @@
+// Workaround https://github.com/cloudflare/workers-sdk/issues/6577
+import type { Middleware } from 'waku/config';
+
+function isWranglerDev(headers?: Record<string, string | string[]>): boolean {
+  // This header seems to only be set for production cloudflare workers
+  return !headers?.['cf-visitor'];
+}
+
+const cloudflareMiddleware: Middleware = () => {
+  return async (ctx, next) => {
+    await next();
+    if (!import.meta.env?.PROD) {
+      return;
+    }
+    if (!isWranglerDev(ctx.req.headers)) {
+      return;
+    }
+    const contentType = ctx.res.headers?.['content-type'];
+    if (
+      !contentType ||
+      contentType.includes('text/html') ||
+      contentType.includes('text/plain')
+    ) {
+      ctx.res.headers ||= {};
+      ctx.res.headers['content-encoding'] = 'Identity';
+    }
+  };
+};
+
+export default cloudflareMiddleware;

examples/07_cloudflare/waku.config.ts

@@ -31,6 +31,7 @@ export default defineConfig({
     return [
       import('waku/middleware/context'),
       import('waku/middleware/dev-server'),
+      import('./waku.cloudflare-middleware'),
       import('waku/middleware/handler'),
     ];
   },