Fix internal Future v8_middleware field naming

.changeset/kind-tools-suffer.md

@@ -0,0 +1,6 @@
+---
+"@react-router/dev": patch
+"react-router": patch
+---
+
+Fix internal `Future` interface naming from `middleware` -> `v8_middleware`

packages/react-router-dev/typegen/generate.ts

@@ -23,7 +23,7 @@ export function generateFuture(ctx: Context): VirtualFile {
 
     declare module "react-router" {
       interface Future {
-        middleware: ${ctx.config.future.v8_middleware}
+        v8_middleware: ${ctx.config.future.v8_middleware}
       }
     }
   `;

packages/react-router/lib/types/future.ts

@@ -2,8 +2,13 @@
  * An augmentable interface users can modify in their app-code to opt into
  * future-flag-specific types
  */
-export interface Future {}
+export interface Future {
+  // We list the potential fields here in comments strictly for clarity.
+  // They will be generated by the react-router/dev/typegen/generate.ts module
+  //
+  // v8_middleware: boolean
+}
 
 // prettier-ignore
 export type MiddlewareEnabled =
-  Future extends { middleware: infer T extends boolean; } ? T : false
+  Future extends { v8_middleware: infer T extends boolean; } ? T : false