diff --git a/packages/remix-react/future/single-fetch.d.ts b/packages/remix-react/future/single-fetch.d.ts
index ddef3d7098c..3436e077de1 100644
--- a/packages/remix-react/future/single-fetch.d.ts
+++ b/packages/remix-react/future/single-fetch.d.ts
@@ -1,7 +1,7 @@
 import type { MetaArgs, UIMatch, UNSAFE_MetaMatch } from "@remix-run/react";
 import type {
-  LoaderFunctionArgs,
-  ActionFunctionArgs,
+  Loader,
+  Action,
   SerializeFrom,
   TypedDeferredData,
   TypedResponse,
@@ -11,90 +11,52 @@ import type {
   FetcherWithComponents,
 } from "react-router-dom";
 
-type Serializable =
-  | undefined
-  | null
-  | boolean
-  | string
-  | symbol
-  | number
-  | Array<Serializable>
-  | { [key: PropertyKey]: Serializable }
-  | bigint
-  | Date
-  | URL
-  | RegExp
-  | Error
-  | Map<Serializable, Serializable>
-  | Set<Serializable>
-  | Promise<Serializable>;
-
-type DataFunctionReturnValue =
-  | Serializable
-  | TypedDeferredData<Record<string, unknown>>
-  | TypedResponse<Record<string, unknown>>;
-
-type LoaderFunction_SingleFetch = (
-  args: LoaderFunctionArgs
-) => Promise<DataFunctionReturnValue> | DataFunctionReturnValue;
-type ActionFunction_SingleFetch = (
-  args: ActionFunctionArgs
-) => Promise<DataFunctionReturnValue> | DataFunctionReturnValue;
-
 // Backwards-compatible type for Remix v2 where json/defer still use the old types,
 // and only non-json/defer returns use the new types.  This allows for incremental
 // migration of loaders to return naked objects.  In the next major version,
 // json/defer will be removed so everything will use the new simplified typings.
 // prettier-ignore
-type SingleFetchSerialize_V2<T extends LoaderFunction_SingleFetch | ActionFunction_SingleFetch> =
+type Serialize<T extends Loader | Action> =
   Awaited<ReturnType<T>> extends TypedDeferredData<infer D> ? D :
   Awaited<ReturnType<T>> extends TypedResponse<Record<string, unknown>> ? SerializeFrom<T> :
   Awaited<ReturnType<T>>;
 
 declare module "@remix-run/react" {
-  export function useLoaderData<T>(): T extends LoaderFunction_SingleFetch
-    ? SingleFetchSerialize_V2<T>
-    : never;
+  export function useLoaderData<T>(): T extends Loader ? Serialize<T> : T;
 
-  export function useActionData<T>(): T extends ActionFunction_SingleFetch
-    ? SingleFetchSerialize_V2<T> | undefined
-    : never;
+  export function useActionData<T>(): T extends Action
+    ? Serialize<T> | undefined
+    : T;
 
   export function useRouteLoaderData<T>(
     routeId: string
-  ): T extends LoaderFunction_SingleFetch ? SingleFetchSerialize_V2<T> : never;
+  ): T extends Loader ? Serialize<T> : never;
 
   export function useFetcher<TData = unknown>(
     opts?: Parameters<typeof useFetcherRR>[0]
   ): FetcherWithComponents<
-    TData extends LoaderFunction_SingleFetch | ActionFunction_SingleFetch
-      ? SingleFetchSerialize_V2<TData>
-      : never
+    TData extends Loader | Action ? Serialize<TData> : TData
   >;
 
   export type UIMatch_SingleFetch<D = unknown, H = unknown> = Omit<
     UIMatch<D, H>,
     "data"
   > & {
-    data: D extends LoaderFunction_SingleFetch
-      ? SingleFetchSerialize_V2<D>
-      : never;
+    data: D extends Loader ? Serialize<D> : never;
   };
 
   interface MetaMatch_SingleFetch<
     RouteId extends string = string,
-    Loader extends LoaderFunction_SingleFetch | unknown = unknown
-  > extends Omit<UNSAFE_MetaMatch<RouteId, Loader>, "data"> {
-    data: Loader extends LoaderFunction_SingleFetch
-      ? SingleFetchSerialize_V2<Loader>
-      : unknown;
+    L extends Loader | unknown = unknown
+  > extends Omit<UNSAFE_MetaMatch<RouteId, L>, "data"> {
+    data: L extends Loader ? Serialize<L> : unknown;
   }
 
   type MetaMatches_SingleFetch<
-    MatchLoaders extends Record<
+    MatchLoaders extends Record<string, Loader | unknown> = Record<
       string,
-      LoaderFunction_SingleFetch | unknown
-    > = Record<string, unknown>
+      unknown
+    >
   > = Array<
     {
       [K in keyof MatchLoaders]: MetaMatch_SingleFetch<
@@ -105,17 +67,13 @@ declare module "@remix-run/react" {
   >;
 
   export interface MetaArgs_SingleFetch<
-    Loader extends LoaderFunction_SingleFetch | unknown = unknown,
-    MatchLoaders extends Record<
+    L extends Loader | unknown = unknown,
+    MatchLoaders extends Record<string, Loader | unknown> = Record<
       string,
-      LoaderFunction_SingleFetch | unknown
-    > = Record<string, unknown>
-  > extends Omit<MetaArgs<Loader, MatchLoaders>, "data" | "matches"> {
-    data:
-      | (Loader extends LoaderFunction_SingleFetch
-          ? SingleFetchSerialize_V2<Loader>
-          : unknown)
-      | undefined;
+      unknown
+    >
+  > extends Omit<MetaArgs<L, MatchLoaders>, "data" | "matches"> {
+    data: (L extends Loader ? Serialize<L> : unknown) | undefined;
     matches: MetaMatches_SingleFetch<MatchLoaders>;
   }
 }
diff --git a/packages/remix-server-runtime/index.ts b/packages/remix-server-runtime/index.ts
index 7744129cdb7..5ce73bb3d57 100644
--- a/packages/remix-server-runtime/index.ts
+++ b/packages/remix-server-runtime/index.ts
@@ -6,6 +6,8 @@ export {
 } from "./formData";
 export { defer, json, redirect, redirectDocument } from "./responses";
 export type {
+  Loader,
+  Action,
   SingleFetchResult as UNSAFE_SingleFetchResult,
   SingleFetchResults as UNSAFE_SingleFetchResults,
 } from "./single-fetch";
diff --git a/packages/remix-server-runtime/single-fetch.ts b/packages/remix-server-runtime/single-fetch.ts
index bdfe745f7fc..fb37dccffcb 100644
--- a/packages/remix-server-runtime/single-fetch.ts
+++ b/packages/remix-server-runtime/single-fetch.ts
@@ -1,4 +1,6 @@
 import type {
+  ActionFunctionArgs as RRActionArgs,
+  LoaderFunctionArgs as RRLoaderArgs,
   StaticHandler,
   unstable_DataStrategyFunctionArgs as DataStrategyFunctionArgs,
   unstable_DataStrategyFunction as DataStrategyFunction,
@@ -19,6 +21,7 @@ import type {
   ResponseStubOperation,
 } from "./routeModules";
 import { ResponseStubOperationsSymbol } from "./routeModules";
+import type { TypedDeferredData, TypedResponse } from "./responses";
 import { isDeferredData, isRedirectStatusCode, isResponse } from "./responses";
 
 export const SingleFetchRedirectSymbol = Symbol("SingleFetchRedirect");
@@ -504,3 +507,51 @@ export function encodeViaTurboStream(
     ],
   });
 }
+
+type MaybePromise<T> = T | Promise<T>;
+
+type Serializable =
+  | undefined
+  | null
+  | boolean
+  | string
+  | symbol
+  | number
+  | Array<Serializable>
+  | { [key: PropertyKey]: Serializable }
+  | bigint
+  | Date
+  | URL
+  | RegExp
+  | Error
+  | Map<Serializable, Serializable>
+  | Set<Serializable>
+  | Promise<Serializable>;
+
+type DataFunctionReturnValue =
+  | Serializable
+  | TypedDeferredData<Record<string, unknown>>
+  | TypedResponse<Record<string, unknown>>;
+
+type LoaderArgs = RRLoaderArgs<AppLoadContext> & {
+  // Context is always provided in Remix, and typed for module augmentation support.
+  context: AppLoadContext;
+  response: ResponseStub;
+};
+
+export type Loader = (
+  args: LoaderArgs
+) => MaybePromise<DataFunctionReturnValue>;
+
+type ActionArgs = RRActionArgs<AppLoadContext> & {
+  // Context is always provided in Remix, and typed for module augmentation support.
+  context: AppLoadContext;
+  response: ResponseStub;
+};
+
+export type Action = (
+  args: ActionArgs
+) => MaybePromise<DataFunctionReturnValue>;
+
+export let defineLoader = <T extends Loader>(loader: T): T => loader;
+export let defineAction = <T extends Action>(action: T): T => action;