From 135e24ab886c41050121832de358dbcbeae00019 Mon Sep 17 00:00:00 2001
From: Chanhee Lee <contact@imch.dev>
Date: Sat, 7 Feb 2026 00:54:02 +0900
Subject: [PATCH] fix(plugin-rsc): ensure serverResources CSS precedence is
 registered first

Preinitialize serverResources CSS before client reference CSS to ensure
React discovers the "importer-resources" precedence group first. This
prevents CSS URLs from being deduplicated under the wrong precedence
group when client reference load() is called before the RSC stream's
Resources component renders on the first request.

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>
---
 packages/plugin-rsc/src/ssr.tsx | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/packages/plugin-rsc/src/ssr.tsx b/packages/plugin-rsc/src/ssr.tsx
index 2fb4fd40b..942ab9ef2 100644
--- a/packages/plugin-rsc/src/ssr.tsx
+++ b/packages/plugin-rsc/src/ssr.tsx
@@ -81,6 +81,25 @@ function wrapResourceProxy(mod: any, id: string, deps: ResolvedAssetDeps) {
   })
 }
 
+// Ensure serverResources CSS is registered before clientReferenceDeps CSS
+// so that React discovers the "importer-resources" precedence group first.
+// Without this, on the first request the client reference's `load()` can call
+// `preloadDeps()` before the RSC stream's `<Resources>` component renders,
+// causing "client-reference" to be discovered first and shared CSS URLs to be
+// deduplicated under the wrong precedence group.
+function preinitServerResources() {
+  if (!assetsManifest.serverResources) return
+  if (assetsManifest.cssLinkPrecedence === false) return
+  for (const resource of Object.values(assetsManifest.serverResources)) {
+    for (const href of resource.css) {
+      ReactDOM.preinit(href, {
+        as: 'style',
+        precedence: 'vite-rsc/importer-resources',
+      })
+    }
+  }
+}
+
 function preloadDeps(deps: ResolvedAssetDeps) {
   for (const href of deps.js) {
     ReactDOM.preloadModule(href, {
@@ -90,6 +109,8 @@ function preloadDeps(deps: ResolvedAssetDeps) {
       crossOrigin: '',
     })
   }
+  // register serverResources precedence before client CSS
+  preinitServerResources()
   for (const href of deps.css) {
     ReactDOM.preinit(href, {
       as: 'style',