From 97fadb4d0b81288ebe26708ed288faeb9e174b1a Mon Sep 17 00:00:00 2001
From: Maks Pikov <mixelburg@users.noreply.github.com>
Date: Sun, 5 Apr 2026 22:46:13 +0000
Subject: [PATCH 1/2] fix(react-router): preserve inline head scripts in React
 tree after hydration

---
 packages/react-router/src/Asset.tsx | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/packages/react-router/src/Asset.tsx b/packages/react-router/src/Asset.tsx
index 4de655fed8a..f4016ae2409 100644
--- a/packages/react-router/src/Asset.tsx
+++ b/packages/react-router/src/Asset.tsx
@@ -215,5 +215,19 @@ function Script({
     }
   }
 
+  // For inline scripts (children, no src), keep the element in the React tree after
+  // hydration so React doesn't unmount the SSR-rendered script from the DOM.
+  // The useEffect above detects the existing element via textContent match and skips
+  // re-injection, so the script won't execute a second time.
+  if (!attrs?.src && typeof children === 'string') {
+    return (
+      <script
+        {...attrs}
+        dangerouslySetInnerHTML={{ __html: children }}
+        suppressHydrationWarning
+      />
+    )
+  }
+
   return null
 }

From 0aeed95e2f8bb14e3d1e2c9e97faaa8d5aa16430 Mon Sep 17 00:00:00 2001
From: Maks Pikov <mixelburg@users.noreply.github.com>
Date: Tue, 7 Apr 2026 00:08:48 +0000
Subject: [PATCH 2/2] fix(react-router): guard inline-script SSR path with
 wentThroughNonHydratedPhase ref
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Narrows the dangerouslySetInnerHTML React-tree-preservation guard to only
activate for components that went through the SSR pre-hydration phase.

On client-side navigation useHydrated() immediately returns true, so
wentThroughNonHydratedPhase.current is false and we fall through to
return null — the useEffect handles imperative injection instead.

Without this fix, client navigation caused React to render an inert
dangerouslySetInnerHTML script that the useEffect dedup check mistook
for an already-executed script, so the script was never actually run.

Fixes the 3 failing tests in Scripts.test.tsx.
---
 packages/react-router/src/Asset.tsx | 20 +++++++++++++++++---
 1 file changed, 17 insertions(+), 3 deletions(-)

diff --git a/packages/react-router/src/Asset.tsx b/packages/react-router/src/Asset.tsx
index f4016ae2409..fa29d5dfc0b 100644
--- a/packages/react-router/src/Asset.tsx
+++ b/packages/react-router/src/Asset.tsx
@@ -51,6 +51,11 @@ function Script({
 }) {
   const router = useRouter()
   const hydrated = useHydrated()
+  // Track whether this component instance went through the !hydrated (pre-hydration) phase.
+  // true  → component was SSR-rendered; the inline script was already executed by the browser.
+  // false → component was mounted fresh on the client (client-side navigation); useEffect must
+  //         inject an executable script because dangerouslySetInnerHTML never executes scripts.
+  const wentThroughNonHydratedPhase = React.useRef(!hydrated)
   const dataScript =
     typeof attrs?.type === 'string' &&
     attrs.type !== '' &&
@@ -215,11 +220,20 @@ function Script({
     }
   }
 
-  // For inline scripts (children, no src), keep the element in the React tree after
-  // hydration so React doesn't unmount the SSR-rendered script from the DOM.
+  // For inline scripts (children, no src) that went through SSR hydration, keep the element
+  // in the React tree so React doesn't unmount the SSR-rendered script from the DOM.
   // The useEffect above detects the existing element via textContent match and skips
   // re-injection, so the script won't execute a second time.
-  if (!attrs?.src && typeof children === 'string') {
+  //
+  // For client-side navigation (wentThroughNonHydratedPhase === false), skip this path and
+  // fall through to return null — the useEffect handles imperative injection in that case.
+  // (dangerouslySetInnerHTML does not execute scripts, so we must not render an inert element
+  // that would fool the existingScript dedup check into returning early without executing.)
+  if (
+    !attrs?.src &&
+    typeof children === 'string' &&
+    wentThroughNonHydratedPhase.current
+  ) {
     return (
       <script
         {...attrs}