Add back-compat for manifest parameter

Author: brophdawg11

.changeset/rare-jobs-remember.md

@@ -0,0 +1,5 @@
+---
+"react-router": patch
+---
+
+[REMOVE] Follow up to https://github.com/remix-run/react-router/pull/14321 to avoid issues with rolling deployments

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

@@ -354,19 +354,15 @@ async function handleManifestRequest(
 
   let patches: Record<string, EntryRoute> = {};
 
-  if (url.searchParams.has("paths")) {
+  // Support both the old (`p`) and new formats (`paths`) to avoid issues during
+  // rolling deployments where an old client hits a new server
+  if (url.searchParams.has("p") || url.searchParams.has("paths")) {
     let paths = new Set<string>();
 
-    // In addition to responding with the patches for the requested paths, we
-    // need to include patches for each partial path so that we pick up any
-    // pathless/index routes below ancestor segments.  So if we
-    // get a request for `/parent/child`, we need to look for a match on `/parent`
-    // so that if a `parent._index` route exists we return it so it's available
-    // for client side matching if the user routes back up to `/parent`.
-    // This is the same thing we do on initial load in <Scripts> via
-    // `getPartialManifest()`
-    let pathParam = url.searchParams.get("paths") || "";
-    let requestedPaths = pathParam.split(",").filter(Boolean);
+    let requestedPaths = url.searchParams.has("paths")
+      ? (url.searchParams.get("paths") || "").split(",").filter(Boolean)
+      : url.searchParams.getAll("p");
+
     requestedPaths.forEach((path) => {
       if (!path.startsWith("/")) {
         path = `/${path}`;
@@ -378,6 +374,14 @@ async function handleManifestRequest(
       });
     });
 
+    // In addition to responding with the patches for the requested paths, we
+    // need to include patches for each partial path so that we pick up any
+    // pathless/index routes below ancestor segments.  So if we
+    // get a request for `/parent/child`, we need to look for a match on `/parent`
+    // so that if a `parent._index` route exists we return it so it's available
+    // for client side matching if the user routes back up to `/parent`.
+    // This is the same thing we do on initial load in <Scripts> via
+    // `getPartialManifest()`
     for (let path of paths) {
       let matches = matchServerRoutes(routes, path, build.basename);
       if (matches) {