From ece954123b23e7131e9862e224450d3892056fe5 Mon Sep 17 00:00:00 2001
From: Albert Martinez <58224660+albert-mr@users.noreply.github.com>
Date: Mon, 3 Nov 2025 15:57:18 +0700
Subject: [PATCH] fix: default to zero address for read operations when account
 not provided

Previously, readContract and simulateWriteContract would pass undefined
as the 'from' parameter when no account was provided, causing RPC errors.

This fix defaults to the zero address (0x0000...0000) when no account is
specified, following Ethereum standards (eth_call behavior). This allows
read-only operations to work without requiring wallet connection.

Changes:
- src/contracts/actions.ts: Added ?? zeroAddress fallback for both
  readContract (L74) and simulateWriteContract (L123)
- tests/client.test.ts: Added test coverage for zero address default

Fixes the issue where users received "Details: 'from'" errors when
attempting to read contract state without providing an account.
---
 src/contracts/actions.ts |  4 ++--
 tests/client.test.ts     | 26 ++++++++++++++++++++++++++
 2 files changed, 28 insertions(+), 2 deletions(-)

diff --git a/src/contracts/actions.ts b/src/contracts/actions.ts
index a8b7362..8940f70 100644
--- a/src/contracts/actions.ts
+++ b/src/contracts/actions.ts
@@ -71,7 +71,7 @@ export const contractActions = (client: GenLayerClient<GenLayerChain>, publicCli
       const encodedData = [calldata.encode(calldata.makeCalldataObject(functionName, callArgs, kwargs)), leaderOnly];
       const serializedData = serialize(encodedData);
 
-      const senderAddress = account?.address ?? client.account?.address;
+      const senderAddress = account?.address ?? client.account?.address ?? zeroAddress;
 
       const requestParams = {
         type: "read",
@@ -120,7 +120,7 @@ export const contractActions = (client: GenLayerClient<GenLayerChain>, publicCli
       const encodedData = [calldata.encode(calldata.makeCalldataObject(functionName, callArgs, kwargs)), leaderOnly];
       const serializedData = serialize(encodedData);
 
-      const senderAddress = account?.address ?? client.account?.address;
+      const senderAddress = account?.address ?? client.account?.address ?? zeroAddress;
 
       const requestParams = {
         type: "write",
diff --git a/tests/client.test.ts b/tests/client.test.ts
index f75241e..9b242f7 100644
--- a/tests/client.test.ts
+++ b/tests/client.test.ts
@@ -5,6 +5,7 @@ import {Address} from "../src/types/accounts";
 import {createAccount, generatePrivateKey} from "../src/accounts/account";
 import {vi} from "vitest";
 import {TransactionHashVariant} from "../src/types/transactions";
+import {zeroAddress} from "viem";
 
 // Setup fetch mock
 const mockFetch = vi.fn();
@@ -168,4 +169,29 @@ describe("Client Overrides", () => {
       },
     ]);
   });
+
+  it("should use zero address when no account is provided anywhere", async () => {
+    const client = createClient({
+      chain: localnet,
+      // No account provided on client
+    });
+
+    const contractAddress = "0x1234567890123456789012345678901234567890";
+    await client.readContract({
+      // No account override either
+      address: contractAddress as Address,
+      functionName: "testFunction",
+      args: ["arg1", "arg2"],
+    });
+
+    expect(lastGenCallParams).toEqual([
+      {
+        type: "read",
+        to: contractAddress,
+        from: zeroAddress, // Should default to zero address
+        data: expect.any(String),
+        transaction_hash_variant: TransactionHashVariant.LATEST_NONFINAL,
+      },
+    ]);
+  });
 });