feat: add backward compatibility

Author: MaxMoskalenko

sdk/src/client/signer.ts

@@ -62,6 +62,42 @@ export class WalletStateSigner implements StateSigner {
     }
 }
 
+/**
+ * Implementation of the StateSigner interface using a viem Account.
+ * This class uses the account to sign states and raw messages.
+ * It is suitable for use in scenarios where the account is available and can sign messages,
+ * e.g. signing with a private key or other account providers.
+ */
+export class AccountStateSigner implements StateSigner {
+    private readonly account: Account;
+
+    constructor(account: Account) {
+        this.account = account;
+    }
+
+    getAddress(): Address {
+        return this.account.address;
+    }
+
+    async signState(channelId: Hex, state: State): Promise<Hex> {
+        if (!this.account.signMessage) {
+            throw new Error('Account does not support message signing');
+        }
+
+        const packedState = getPackedState(channelId, state);
+
+        return this.account.signMessage({ message: { raw: packedState } });
+    }
+
+    async signRawMessage(message: Hex): Promise<Hex> {
+        if (!this.account.signMessage) {
+            throw new Error('Account does not support message signing');
+        }
+
+        return this.account.signMessage({ message: { raw: message } });
+    }
+}
+
 /**
  * Implementation of the StateSigner interface using a session key.
  * This class uses a session key to sign states and raw messages.

sdk/src/client/state.ts

@@ -2,7 +2,7 @@ import { Address, zeroAddress } from 'viem';
 import * as Errors from '../errors';
 import { getChannelId, getPackedChallengeState } from '../utils';
 import { PreparerDependencies } from './prepare';
-import { StateSigner, WalletStateSigner } from './signer';
+import { AccountStateSigner, SessionKeyStateSigner, StateSigner, WalletStateSigner } from './signer';
 import {
     ChallengeChannelParams,
     ChannelId,
@@ -199,8 +199,8 @@ async function _fetchParticipantAndGetSigner(deps: PreparerDependencies, channel
  */
 function _checkParticipantAndGetSigner(deps: PreparerDependencies, participant: Address): StateSigner {
     let signer = deps.stateSigner;
-    // if (participant == deps.account.address) {
-    //     signer = new WalletStateSigner(deps.account);
-    // }
+    if (participant == deps.account.address && signer instanceof SessionKeyStateSigner) {
+        signer = new AccountStateSigner(deps.account);
+    }
     return signer;
 }