fix(ios): honor echoMessages=false in client options

ios/ably_pubsub_device_flutter/Package.swift

@@ -70,5 +70,14 @@ let package = Package(
                 .product(name: "FlutterFramework", package: "FlutterFramework"),
             ]
         ),
+        .testTarget(
+            name: "AblyFlutterCodecTests",
+            dependencies: [
+                "ably_pubsub_device_flutter",
+                "AblyFlutterCommon",
+                .product(name: "FlutterFramework", package: "FlutterFramework"),
+                .product(name: "AblyPubSubDevice", package: "ably-pubsub-cocoa"),
+            ]
+        ),
     ]
 )

ios/ably_pubsub_device_flutter/Sources/ably_pubsub_device_flutter/codec/AblyFlutterReader.m

@@ -129,7 +129,8 @@ use an explicitly received null from Dart (manifesting this side as a nil id)
     READ_BOOL(clientOptions, autoConnect, dictionary, TxClientOptions_autoConnect);
     READ_VALUE(clientOptions, useBinaryProtocol, dictionary, TxClientOptions_useBinaryProtocol);
     READ_VALUE(clientOptions, queueMessages, dictionary, TxClientOptions_queueMessages);
-    READ_VALUE(clientOptions, echoMessages, dictionary, TxClientOptions_echoMessages);
+    // Unbox NSNumber so an explicit false is not treated as a non-null pointer.
+    READ_BOOL(clientOptions, echoMessages, dictionary, TxClientOptions_echoMessages);
     READ_VALUE(clientOptions, recover, dictionary, TxClientOptions_recover);
     READ_VALUE(clientOptions, idempotentRestPublishing, dictionary, TxClientOptions_idempotentRestPublishing);
     READ_VALUE(clientOptions, fallbackHosts, dictionary, TxClientOptions_fallbackHosts);

ios/ably_pubsub_device_flutter/Tests/AblyFlutterCodecTests/AblyFlutterReaderTests.m

@@ -0,0 +1,53 @@
+#import <XCTest/XCTest.h>
+#import <Flutter/Flutter.h>
+@import AblyPubSubDevice;
+@import AblyFlutterCommon;
+
+// Exercise the production decoder without making its header part of the public API.
+#import "../../Sources/ably_pubsub_device_flutter/codec/AblyFlutterReader.h"
+
+@interface AblyFlutterReaderTests : XCTestCase
+@end
+
+@implementation AblyFlutterReaderTests
+
+// Match Dart's ClientOptions wire format using Flutter's real standard codec.
+- (ARTClientOptions*)decodeClientOptions:(NSDictionary*)options {
+    NSMutableData *data = [NSMutableData data];
+    FlutterStandardWriter *writer = [[FlutterStandardWriter alloc] initWithData:data];
+    [writer writeByte:CodecTypeClientOptions];
+    [writer writeValue:options];
+
+    AblyFlutterReader *reader = [[AblyFlutterReader alloc] initWithData:data];
+    AblyFlutterClientOptions *decoded = [reader readValue];
+    XCTAssertTrue([decoded isKindOfClass:[AblyFlutterClientOptions class]]);
+    XCTAssertNotNil(decoded.clientOptions);
+    return decoded.clientOptions;
+}
+
+// A boxed false from Flutter must disable echoes on the native client.
+- (void)testEchoMessagesFalseIsPreserved {
+    ARTClientOptions *options = [self decodeClientOptions:@{TxClientOptions_echoMessages: @NO}];
+    XCTAssertFalse(options.echoMessages,
+        @"An explicit false must disable echoes instead of treating NSNumber as a truthy pointer");
+}
+
+// Explicit true must continue to enable echoes.
+- (void)testEchoMessagesTrueIsPreserved {
+    ARTClientOptions *options = [self decodeClientOptions:@{TxClientOptions_echoMessages: @YES}];
+    XCTAssertTrue(options.echoMessages);
+}
+
+// An omitted option must preserve the native SDK's documented default.
+- (void)testMissingEchoMessagesKeepsDefault {
+    ARTClientOptions *options = [self decodeClientOptions:@{}];
+    XCTAssertTrue(options.echoMessages);
+}
+
+// Null means the caller did not override the native default.
+- (void)testNullEchoMessagesKeepsDefault {
+    ARTClientOptions *options = [self decodeClientOptions:@{TxClientOptions_echoMessages: [NSNull null]}];
+    XCTAssertTrue(options.echoMessages);
+}
+
+@end