Fix 304 case

Author: brophdawg11

packages/react-router/lib/dom/ssr/single-fetch.tsx

@@ -55,9 +55,13 @@ interface StreamTransferProps {
   nonce?: string;
 }
 
-// some status codes are not permitted to have bodies, so we want to just
-// treat those as "no data" instead of throwing an exception.
-// 304 is not included here because the browser should fill those responses
+// Some status codes are not permitted to have bodies, so we want to just
+// treat those as "no data" instead of throwing an exception:
+//   https://datatracker.ietf.org/doc/html/rfc9110#name-informational-1xx
+//   https://datatracker.ietf.org/doc/html/rfc9110#name-204-no-content
+//   https://datatracker.ietf.org/doc/html/rfc9110#name-205-reset-content
+//
+// Note: 304 is not included here because the browser should fill those responses
 // with the cached body content.
 export const NO_BODY_STATUS_CODES = new Set([100, 101, 204, 205]);
 

packages/react-router/lib/server-runtime/server.ts

@@ -30,17 +30,15 @@ import {
   singleFetchAction,
   singleFetchLoaders,
   SINGLE_FETCH_REDIRECT_STATUS,
+  SERVER_NO_BODY_STATUS_CODES,
 } from "./single-fetch";
 import { getDocumentHeaders } from "./headers";
 import type { EntryRoute } from "../dom/ssr/routes";
 import type {
   SingleFetchResult,
   SingleFetchResults,
 } from "../dom/ssr/single-fetch";
-import {
-  NO_BODY_STATUS_CODES,
-  SingleFetchRedirectSymbol,
-} from "../dom/ssr/single-fetch";
+import { SingleFetchRedirectSymbol } from "../dom/ssr/single-fetch";
 import type { MiddlewareEnabled } from "../types/future";
 
 export type RequestHandler = (
@@ -453,7 +451,7 @@ async function handleDocumentRequest(
     let headers = getDocumentHeaders(build, context);
 
     // Skip response body for unsupported status codes
-    if (NO_BODY_STATUS_CODES.has(context.statusCode)) {
+    if (SERVER_NO_BODY_STATUS_CODES.has(context.statusCode)) {
       return new Response(null, { status: context.statusCode, headers });
     }
 

packages/react-router/lib/server-runtime/single-fetch.ts

@@ -35,6 +35,14 @@ import type { ServerBuild } from "./build";
 // the user control cache behavior via Cache-Control
 export const SINGLE_FETCH_REDIRECT_STATUS = 202;
 
+// Add 304 for server side - that is not included in the client side logic
+// because the browser should fill those responses with the cached data
+// https://datatracker.ietf.org/doc/html/rfc9110#name-304-not-modified
+export const SERVER_NO_BODY_STATUS_CODES = new Set([
+  ...NO_BODY_STATUS_CODES,
+  304,
+]);
+
 export async function singleFetchAction(
   build: ServerBuild,
   serverMode: ServerMode,
@@ -269,7 +277,7 @@ function generateSingleFetchResponse(
   resultHeaders.set("X-Remix-Response", "yes");
 
   // Skip response body for unsupported status codes
-  if (NO_BODY_STATUS_CODES.has(status)) {
+  if (SERVER_NO_BODY_STATUS_CODES.has(status)) {
     return new Response(null, { status, headers: resultHeaders });
   }