From 62bd43f76b56e6f7010ad5671355954226fda3bf Mon Sep 17 00:00:00 2001
From: ShaneK <shane@shanessite.net>
Date: Wed, 11 Mar 2026 10:44:55 -0700
Subject: [PATCH] fix(react-router): sort fallback params by specificity to
 prevent less-specific overwrites

---
 .../src/ReactRouter/ReactRouterViewStack.tsx     | 16 ++++++++++++++--
 1 file changed, 14 insertions(+), 2 deletions(-)

diff --git a/packages/react-router/src/ReactRouter/ReactRouterViewStack.tsx b/packages/react-router/src/ReactRouter/ReactRouterViewStack.tsx
index d3dc8e537f..efb57b96c3 100644
--- a/packages/react-router/src/ReactRouter/ReactRouterViewStack.tsx
+++ b/packages/react-router/src/ReactRouter/ReactRouterViewStack.tsx
@@ -89,7 +89,7 @@ const getFallbackParamsFromViewItems = (
   currentOutletId: string,
   currentPathname: string
 ): RouteParams => {
-  const params: RouteParams = {};
+  const matchingViews: { params: RouteParams; pathLength: number }[] = [];
 
   for (const otherViewItem of allViewItems) {
     if (otherViewItem.outletId === currentOutletId) continue;
@@ -98,11 +98,23 @@ const getFallbackParamsFromViewItems = (
     if (otherMatch?.params && Object.keys(otherMatch.params).length > 0) {
       const matchedPathname = otherMatch.pathnameBase || otherMatch.pathname;
       if (matchedPathname && currentPathname.startsWith(matchedPathname)) {
-        Object.assign(params, otherMatch.params);
+        matchingViews.push({
+          params: otherMatch.params,
+          pathLength: matchedPathname.length,
+        });
       }
     }
   }
 
+  // Sort ascending by path length so more-specific (longer) paths are applied
+  // last and their params take priority over less-specific ones.
+  matchingViews.sort((a, b) => a.pathLength - b.pathLength);
+
+  const params: RouteParams = {};
+  for (const view of matchingViews) {
+    Object.assign(params, view.params);
+  }
+
   return params;
 };