Hide memo row on unrelated operations

src/components/screens/HistoryScreen/TransactionDetailsBottomSheetCustomContent.tsx

@@ -3,6 +3,7 @@ import { List, ListItemProps } from "components/List";
 import {
   renderActionIcon,
   renderIconComponent,
+  shouldShowMemo,
 } from "components/screens/HistoryScreen/helpers";
 import { CreateAccountTransactionDetailsContent } from "components/screens/HistoryScreen/mappers/createAccount";
 import { PaymentTransactionDetailsContent } from "components/screens/HistoryScreen/mappers/payment";
@@ -164,8 +165,9 @@ export const TransactionDetailsBottomSheetCustomContent: React.FC<
             </Text>
           ),
         },
-        // Hide memo line for M addresses (memo is encoded in the address)
-        !isDestinationMuxed
+        // Show memo only for classic Send/Receive (Payment/CreateAccount) operations
+        // and hide for M addresses (memo is encoded in the address)
+        shouldShowMemo(transactionDetails.transactionType, isDestinationMuxed)
           ? {
               icon: (
                 <Icon.File02 size={16} color={themeColors.foreground.primary} />

src/components/screens/HistoryScreen/helpers.test.ts

@@ -0,0 +1,46 @@
+import { shouldShowMemo } from "components/screens/HistoryScreen/helpers";
+import { TransactionType } from "components/screens/HistoryScreen/types";
+
+describe("shouldShowMemo", () => {
+  describe("returns true (show memo)", () => {
+    it("shows memo for PAYMENT when destination is not muxed", () => {
+      expect(shouldShowMemo(TransactionType.PAYMENT, false)).toBe(true);
+    });
+
+    it("shows memo for CREATE_ACCOUNT when destination is not muxed", () => {
+      expect(shouldShowMemo(TransactionType.CREATE_ACCOUNT, false)).toBe(true);
+    });
+  });
+
+  describe("returns false (hide memo) for muxed destinations", () => {
+    it("hides memo for PAYMENT when destination is muxed", () => {
+      expect(shouldShowMemo(TransactionType.PAYMENT, true)).toBe(false);
+    });
+
+    it("hides memo for CREATE_ACCOUNT when destination is muxed", () => {
+      expect(shouldShowMemo(TransactionType.CREATE_ACCOUNT, true)).toBe(false);
+    });
+  });
+
+  describe("returns false (hide memo) for non-classic transaction types", () => {
+    const nonClassicTypes = [
+      TransactionType.SWAP,
+      TransactionType.CHANGE_TRUST,
+      TransactionType.CONTRACT,
+      TransactionType.CONTRACT_MINT,
+      TransactionType.CONTRACT_TRANSFER,
+      TransactionType.UNKNOWN,
+    ];
+
+    it.each(nonClassicTypes)(
+      "hides memo for %s (not muxed)",
+      (transactionType) => {
+        expect(shouldShowMemo(transactionType, false)).toBe(false);
+      },
+    );
+
+    it.each(nonClassicTypes)("hides memo for %s (muxed)", (transactionType) => {
+      expect(shouldShowMemo(transactionType, true)).toBe(false);
+    });
+  });
+});

src/components/screens/HistoryScreen/helpers.tsx

@@ -1,6 +1,7 @@
 /* eslint-disable @typescript-eslint/restrict-template-expressions */
 /* eslint-disable @typescript-eslint/no-unsafe-enum-comparison */
 import { Horizon } from "@stellar/stellar-sdk";
+import { TransactionType } from "components/screens/HistoryScreen/types";
 import Icon from "components/sds/Icon";
 import { OPERATION_TYPES } from "config/constants";
 import { SorobanTokenInterface } from "helpers/soroban";
@@ -93,3 +94,27 @@ export const isSorobanTokenMint = (fnName: string | undefined): boolean =>
  */
 export const isSorobanTokenTransfer = (fnName: string | undefined): boolean =>
   fnName === SorobanTokenInterface.transfer;
+
+/**
+ * Determines if the memo field should be displayed for a transaction.
+ * Memo is only relevant for classic Send/Receive operations (Payment and
+ * CreateAccount). It is also hidden when the destination is a muxed address
+ * Determines if the memo field should be displayed in the History details UI
+ * for a given transaction.
+ *
+ * Although Stellar allows attaching a memo to any transaction, this screen
+ * currently only shows the memo for classic Send/Receive operations
+ * (Payment and CreateAccount). The memo is also hidden when the destination
+ * is a muxed address, since the destination address already encodes the
+ * memo-like data.
+ */
+export const shouldShowMemo = (
+  transactionType: TransactionType,
+  isDestinationMuxed: boolean,
+): boolean => {
+  const isClassicSendReceive =
+    transactionType === TransactionType.PAYMENT ||
+    transactionType === TransactionType.CREATE_ACCOUNT;
+
+  return isClassicSendReceive && !isDestinationMuxed;
+};