MetaMask · mcmire · Nov 12, 2025
@@ -7,21 +7,27 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Added
+
+- Add new function `providerAsMiddlewareV2` for converting an `InternalProvider` into a `JsonRpcEngine` v2-compatible middleware ([#7138](https://github.com/MetaMask/core/pull/7138))
+
 ### Changed
 
-- **BREAKING:** Migrate to `JsonRpcEngineV2` ([#7065](https://github.com/MetaMask/core/pull/7065))
-  - Migrates all middleware from `JsonRpcEngine` to `JsonRpcEngineV2`.
-  - Signatures of various middleware dependencies, e.g. `processTransaction` of `createWalletMiddleware`, have changed
-    and must be updated by consumers.
-    - Be advised that request objects are now deeply frozen, and cannot be mutated.
+- **BREAKING:** Migrate all middleware from `JsonRpcEngine` to `JsonRpcEngineV2` ([#7065](https://github.com/MetaMask/core/pull/7065))
   - To continue using this package with the legacy `JsonRpcEngine`, use the `asLegacyMiddleware` backwards compatibility function.
+- **BREAKING:** Change the signatures of hooks for `createWalletMiddleware` ([#7065](https://github.com/MetaMask/core/pull/7065))
+  - To wit:
+    - `getAccounts` takes an origin argument (`string`) instead of a `JsonRpcRequest`
+    - `processDecryptMessage` and `processEncryptionPublicKey` take a `MessageRequest` from `@metamask/message-manager` instead of `JsonRpcRequest`
+    - `processPersonalMessage`, `processTransaction`, `processSignTransaction`, `processTypedMessage`, `processTypedMessageV3` and `processTypedMessageV4` take a `context` as the third argument, before any other arguments
+  - Be advised that request objects are now deeply frozen, and cannot be mutated.
 - **BREAKING:** Use `InternalProvider` instead of `SafeEventEmitterProvider` ([#6796](https://github.com/MetaMask/core/pull/6796))
   - Wherever a `SafeEventEmitterProvider` was expected, an `InternalProvider` is now expected instead.
 - **BREAKING:** Stop retrying `undefined` results for methods that include a block tag parameter ([#7001](https://github.com/MetaMask/core/pull/7001))
   - The `retryOnEmpty` middleware will now throw an error if it encounters an `undefined` result when dispatching
     a request with a later block number than the originally requested block number.
   - In practice, this should happen rarely if ever.
-- Migrate all uses of `interface` to `type` ([#6885](https://github.com/MetaMask/core/pull/6885))
+- **BREAKING:** Migrate all uses of `interface` to `type` ([#6885](https://github.com/MetaMask/core/pull/6885))
 
 ## [21.0.0]
 

@@ -11,7 +11,10 @@ import {
 import { projectLogger, createModuleLogger } from './logging-utils';
 import { cacheIdentifierForRequest } from './utils/cache';
 
-type RequestHandler = [(result: Json) => void, (error: Error) => void];
+type RequestHandler = [
+  (result: Readonly<Json>) => void,
+  (error: unknown) => void,
+];
 
 type InflightRequest = {
   [cacheId: string]: RequestHandler[];
@@ -64,7 +67,7 @@ export function createInflightCacheMiddleware(): JsonRpcMiddleware<
     // allow request to be handled normally
     log('Carrying original request forward %o', request);
     try {
-      const result = (await next()) as Json;
+      const result = (await next()) as Readonly<Json>;
       log(
         'Running %i collected handler(s) for successful request %o',
         activeRequestHandlers.length,
@@ -78,7 +81,7 @@ export function createInflightCacheMiddleware(): JsonRpcMiddleware<
         activeRequestHandlers.length,
         request,
       );
-      runRequestHandlers({ error: error as Error }, activeRequestHandlers);
+      runRequestHandlers({ error }, activeRequestHandlers);
       throw error;
     } finally {
       delete inflightRequests[cacheId];
@@ -94,11 +97,11 @@ export function createInflightCacheMiddleware(): JsonRpcMiddleware<
  */
 function createActiveRequestHandler(
   activeRequestHandlers: RequestHandler[],
-): Promise<Json> {
-  const { resolve, promise, reject } = createDeferredPromise<Json>();
+): Promise<Readonly<Json>> {
+  const { resolve, promise, reject } = createDeferredPromise<Readonly<Json>>();
   activeRequestHandlers.push([
-    (result: Json) => resolve(result),
-    (error: Error) => reject(error),
+    (result: Readonly<Json>) => resolve(result),
+    (error: unknown) => reject(error),
   ]);
   return promise;
 }
@@ -110,7 +113,7 @@ function createActiveRequestHandler(
  * @param activeRequestHandlers - The active request handlers.
  */
 function runRequestHandlers(
-  resultOrError: { result: Json } | { error: Error },
+  resultOrError: { result: Readonly<Json> } | { error: unknown },
   activeRequestHandlers: RequestHandler[],
 ): void {
   // use setTimeout so we can handle the original request first

@@ -11,6 +11,11 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 - Rename `OriginalRequest` type to `MessageRequest` and permit string `id` values ([#7065](https://github.com/MetaMask/core/pull/7065))
   - Previously, only number values were permitted for the `id` property.
+  - `OriginalRequest` is kept for backward compatibility.
+
+### Deprecated
+
+- Deprecate `OriginalRequest`; use `MessageRequest` instead ([#7138](https://github.com/MetaMask/core/pull/7138))
 
 ## [14.0.0]
 

@@ -45,6 +45,13 @@ export type MessageRequest = {
   securityAlertResponse?: Record<string, Json>;
 };
 
+/**
+ * Represents the request adding a message.
+ *
+ * @deprecated Please use `MessageRequest` instead.
+ */
+export type OriginalRequest = MessageRequest;
+
 /**
  * @type AbstractMessage
  *

@@ -19,6 +19,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
   - In practice, this should happen rarely if ever.
 - **BREAKING:** Migrate `NetworkClient` to `JsonRpcEngineV2` ([#7065](https://github.com/MetaMask/core/pull/7065))
   - This ought to be unobservable, but we mark it as breaking out of an abundance of caution.
+- **BREAKING:** Update signature of `request` in `AbstractRpcService` and `RpcServiceRequestable` so that the JSON-RPC request must be frozen ([#7138](https://github.com/MetaMask/core/pull/7138))
 - Bump `@metamask/controller-utils` from `^11.14.1` to `^11.15.0` ([#7003](https://github.com/MetaMask/core/pull/7003))
 
 ### Fixed

@@ -106,7 +106,9 @@ export class RpcServiceChain implements RpcServiceRequestable {
    * @throws A "parse" error if the response is not valid JSON.
    */
   async request<Params extends JsonRpcParams, Result extends Json>(
-    jsonRpcRequest: JsonRpcRequest<Params> & { method: 'eth_getBlockByNumber' },
+    jsonRpcRequest: Readonly<JsonRpcRequest<Params>> & {
+      method: 'eth_getBlockByNumber';
+    },
     fetchOptions?: FetchOptions,
   ): Promise<JsonRpcResponse<Result> | JsonRpcResponse<null>>;
 
@@ -129,12 +131,12 @@ export class RpcServiceChain implements RpcServiceRequestable {
    * @throws A "parse" error if the response is not valid JSON.
    */
   async request<Params extends JsonRpcParams, Result extends Json>(
-    jsonRpcRequest: JsonRpcRequest<Params>,
+    jsonRpcRequest: Readonly<JsonRpcRequest<Params>>,
     fetchOptions?: FetchOptions,
   ): Promise<JsonRpcResponse<Result>>;
 
   async request<Params extends JsonRpcParams, Result extends Json>(
-    jsonRpcRequest: JsonRpcRequest<Params>,
+    jsonRpcRequest: Readonly<JsonRpcRequest<Params>>,
     fetchOptions: FetchOptions = {},
   ): Promise<JsonRpcResponse<Result | null>> {
     return this.#services[0].request(jsonRpcRequest, fetchOptions);

@@ -62,7 +62,7 @@ export type RpcServiceRequestable = {
    * Makes a request to the target.
    */
   request<Params extends JsonRpcParams, Result extends Json>(
-    jsonRpcRequest: JsonRpcRequest<Params>,
+    jsonRpcRequest: Readonly<JsonRpcRequest<Params>>,
     fetchOptions?: FetchOptions,
   ): Promise<JsonRpcResponse<Result | null>>;
 };