Remove defer implementation in favor of raw promises

.changeset/chilled-masks-search.md

@@ -0,0 +1,12 @@
+---
+"react-router-dom": major
+"react-router": major
+---
+
+Remove the original `defer` implementation in favor of using raw promises via single fetch and `turbo-stream`. This removes these exports from React Router:
+
+- `defer`
+- `AbortedDeferredError`
+- `type TypedDeferredData`
+- `UNSAFE_DeferredData`
+- `UNSAFE_DEFERRED_SYMBOL`,

integration/client-data-test.ts

@@ -318,13 +318,13 @@ test.describe("Client Data", () => {
           }),
           "app/routes/parent.child.tsx": js`
             import * as React from 'react';
-            import { defer, json } from "react-router"
+            import { json } from "react-router"
             import { Await, useLoaderData } from "react-router"
             export function loader() {
-              return defer({
+              return {
                 message: 'Child Server Loader',
                 lazy: new Promise(r => setTimeout(() => r("Child Deferred Data"), 1000)),
-              });
+              };
             }
             export async function clientLoader({ serverLoader }) {
               let data = await serverLoader();

integration/defer-loader-test.ts

@@ -28,23 +28,23 @@ test.describe("deferred loaders", () => {
         `,
 
         "app/routes/redirect.tsx": js`
-          import { defer } from "react-router";
-          export function loader() {
-            return defer({food: "pizza"}, { status: 301, headers: { Location: "/?redirected" } });
+          export function loader({ response }) {
+            response.status = 301;
+            response.headers.set("Location", "/?redirected");
+            return { food: "pizza" };
           }
           export default function Redirect() {return null;}
         `,
 
         "app/routes/direct-promise-access.tsx": js`
           import * as React from "react";
-          import { defer } from "react-router";
           import { useLoaderData, Link, Await } from "react-router";
           export function loader() {
-            return defer({
+            return {
               bar: new Promise(async (resolve, reject) => {
                 resolve("hamburger");
               }),
-            });
+            };
           }
           let count = 0;
           export default function Index() {