From 3a3e6a3c72038c29c840d0c9ed4cc61c231940da Mon Sep 17 00:00:00 2001
From: "Sota Iguchi (e-chan1007)" <echan041007@gmail.com>
Date: Thu, 25 Jun 2026 23:11:25 +0900
Subject: [PATCH 1/2] fix: patch the createInlinedDataReadableStream function
 not to use the type: "bytes" option in ReadableStream constructor

workerd seems not to correctly support the type: "bytes" option in ReadableStream constructor, that breaks inlined flight data streaming over 4kB.
By removing the type: "bytes" option, the inlined flight data will not be split into multiple chunks, and the streaming will work correctly.
---
 .changeset/shy-laws-wonder.md                 | 10 +++++
 .../cli/build/open-next/createServerBundle.ts |  2 +
 .../flight-readable-stream-type.spec.ts       | 25 ++++++++++++
 .../plugins/flight-readable-stream-type.ts    | 40 +++++++++++++++++++
 4 files changed, 77 insertions(+)
 create mode 100644 .changeset/shy-laws-wonder.md
 create mode 100644 packages/cloudflare/src/cli/build/patches/plugins/flight-readable-stream-type.spec.ts
 create mode 100644 packages/cloudflare/src/cli/build/patches/plugins/flight-readable-stream-type.ts

diff --git a/.changeset/shy-laws-wonder.md b/.changeset/shy-laws-wonder.md
new file mode 100644
index 000000000..a58919754
--- /dev/null
+++ b/.changeset/shy-laws-wonder.md
@@ -0,0 +1,10 @@
+---
+"@opennextjs/cloudflare": patch
+---
+
+fix: patch the createInlinedDataReadableStream function not to use the type: "bytes" option in ReadableStream constructor
+
+workerd seems not to correctly support the type: "bytes" option in ReadableStream constructor, that breaks inlined flight data streaming over 4kB.
+By removing the type: "bytes" option, the inlined flight data will not be split into multiple chunks, and the streaming will work correctly.
+
+(fixes #1225)
diff --git a/packages/cloudflare/src/cli/build/open-next/createServerBundle.ts b/packages/cloudflare/src/cli/build/open-next/createServerBundle.ts
index c556b6026..8107c79cc 100644
--- a/packages/cloudflare/src/cli/build/open-next/createServerBundle.ts
+++ b/packages/cloudflare/src/cli/build/open-next/createServerBundle.ts
@@ -27,6 +27,7 @@ import type { Plugin } from "esbuild";
 
 import { getOpenNextConfig } from "../../../api/config.js";
 import { normalizePath } from "../../utils/normalize-path.js";
+import { patchFlightReadableStreamType } from "../patches/plugins/flight-readable-stream-type.js";
 import { patchResRevalidate } from "../patches/plugins/res-revalidate.js";
 import { patchTurbopackRuntime } from "../patches/plugins/turbopack.js";
 import { patchUseCacheIO } from "../patches/plugins/use-cache.js";
@@ -209,6 +210,7 @@ async function generateBundle(
 		awsPatches.patchBackgroundRevalidation,
 		awsPatches.patchNodeEnvironment,
 		// Cloudflare specific patches
+		patchFlightReadableStreamType,
 		patchResRevalidate,
 		patchUseCacheIO,
 		patchTurbopackRuntime,
diff --git a/packages/cloudflare/src/cli/build/patches/plugins/flight-readable-stream-type.spec.ts b/packages/cloudflare/src/cli/build/patches/plugins/flight-readable-stream-type.spec.ts
new file mode 100644
index 000000000..5cd551b6b
--- /dev/null
+++ b/packages/cloudflare/src/cli/build/patches/plugins/flight-readable-stream-type.spec.ts
@@ -0,0 +1,25 @@
+import { patchCode } from "@opennextjs/aws/build/patch/astCodePatcher.js";
+import { describe, expect, test } from "vitest";
+
+import { rule } from "./flight-readable-stream-type.js";
+
+describe("patchFlightReadableStreamType", () => {
+	test("removes type property", () => {
+		const code = `
+function tl(e,t,r){
+  let n = t ? '<script nonce="">' : "<script>";
+  return new ReadableStream({type: "bytes", start(e){ e.enqueue(n); }});
+}
+`;
+
+		expect(patchCode(code, rule)).toMatchInlineSnapshot(
+			`
+      "function tl(e,t,r){
+        let n = t ? '<script nonce="">' : "<script>";
+        return new ReadableStream({start(e){ e.enqueue(n); }});
+      }
+      "
+      `
+		);
+	});
+});
diff --git a/packages/cloudflare/src/cli/build/patches/plugins/flight-readable-stream-type.ts b/packages/cloudflare/src/cli/build/patches/plugins/flight-readable-stream-type.ts
new file mode 100644
index 000000000..a4e1b9b49
--- /dev/null
+++ b/packages/cloudflare/src/cli/build/patches/plugins/flight-readable-stream-type.ts
@@ -0,0 +1,40 @@
+/**
+ * This patch will remove the `type: "bytes"` option from the `ReadableStream` constructor in the
+ * createInlinedDataReadableStream function, which provides inline script tag chunks for writing hydration data to the client.
+ * Since workerd has no enough support for the `bytes` type, this patch will remove it to avoid errors related to RSC Flight streams.
+ */
+
+import { patchCode } from "@opennextjs/aws/build/patch/astCodePatcher.js";
+import type { CodePatcher } from "@opennextjs/aws/build/patch/codePatcher.js";
+import { getCrossPlatformPathRegex } from "@opennextjs/aws/utils/regex.js";
+
+export const patchFlightReadableStreamType: CodePatcher = {
+	name: "patch-flight-readable-stream-type",
+	patches: [
+		{
+			pathFilter: getCrossPlatformPathRegex(String.raw`next-server/.*\.runtime\.prod\.js$`, {
+				escape: false,
+			}),
+			contentFilter: /new ReadableStream\(\{type:"bytes",/,
+			patchCode: async ({ code }) => patchCode(code, rule),
+		},
+	],
+};
+
+export const rule = `
+rule:
+  kind: object
+  pattern: "{ type: \\"bytes\\", $$$REST }"
+  inside:
+    stopBy: end
+    kind: new_expression
+    has:
+      field: constructor
+      pattern: ReadableStream
+    inside:
+      stopBy: end
+      has:
+        regex: "<script>"
+
+fix: "{$$$REST}"
+`;

From e9bf4372889d3e5d18a05deaa1f63199866849f3 Mon Sep 17 00:00:00 2001
From: "Sota Iguchi (e-chan1007)" <echan041007@gmail.com>
Date: Fri, 26 Jun 2026 15:53:08 +0900
Subject: [PATCH 2/2] fix: refine the patch rule

add `kind: function_declaration` and specificity test
---
 .../plugins/flight-readable-stream-type.spec.ts  | 16 ++++++++++++++--
 .../plugins/flight-readable-stream-type.ts       |  1 +
 2 files changed, 15 insertions(+), 2 deletions(-)

diff --git a/packages/cloudflare/src/cli/build/patches/plugins/flight-readable-stream-type.spec.ts b/packages/cloudflare/src/cli/build/patches/plugins/flight-readable-stream-type.spec.ts
index 5cd551b6b..0c3979519 100644
--- a/packages/cloudflare/src/cli/build/patches/plugins/flight-readable-stream-type.spec.ts
+++ b/packages/cloudflare/src/cli/build/patches/plugins/flight-readable-stream-type.spec.ts
@@ -4,20 +4,32 @@ import { describe, expect, test } from "vitest";
 import { rule } from "./flight-readable-stream-type.js";
 
 describe("patchFlightReadableStreamType", () => {
-	test("removes type property", () => {
+	test("removes type property of ReadableStream constructor only in createInlinedDataReadableStream", () => {
 		const code = `
+new ReadableStream({type: "bytes", start(e){ e.enqueue(n); }});
+
 function tl(e,t,r){
   let n = t ? '<script nonce="">' : "<script>";
   return new ReadableStream({type: "bytes", start(e){ e.enqueue(n); }});
 }
+
+function tl2(e,t,r){
+  return new ReadableStream({type: "bytes", start(e){ e.enqueue(n); }});
+}
 `;
 
 		expect(patchCode(code, rule)).toMatchInlineSnapshot(
 			`
-      "function tl(e,t,r){
+      "new ReadableStream({type: "bytes", start(e){ e.enqueue(n); }});
+
+      function tl(e,t,r){
         let n = t ? '<script nonce="">' : "<script>";
         return new ReadableStream({start(e){ e.enqueue(n); }});
       }
+
+      function tl2(e,t,r){
+        return new ReadableStream({type: "bytes", start(e){ e.enqueue(n); }});
+      }
       "
       `
 		);
diff --git a/packages/cloudflare/src/cli/build/patches/plugins/flight-readable-stream-type.ts b/packages/cloudflare/src/cli/build/patches/plugins/flight-readable-stream-type.ts
index a4e1b9b49..b604b107a 100644
--- a/packages/cloudflare/src/cli/build/patches/plugins/flight-readable-stream-type.ts
+++ b/packages/cloudflare/src/cli/build/patches/plugins/flight-readable-stream-type.ts
@@ -32,6 +32,7 @@ rule:
       field: constructor
       pattern: ReadableStream
     inside:
+      kind: function_declaration
       stopBy: end
       has:
         regex: "<script>"