pass agent param when fetching realtime channel

TODO test

Source/ARTClientInformation.m

@@ -31,7 +31,7 @@ + (NSString *)agentIdentifierWithAdditionalAgents:(nullable NSDictionary<NSStrin
     for (NSString *const additionalAgentName in additionalAgents) {
         agents[additionalAgentName] = additionalAgents[additionalAgentName];
     }
-    
+
     return [self agentIdentifierForAgents:agents];
 }
 

Source/ARTRealtimeWrapperSDKProxy.m

@@ -2,6 +2,8 @@
 #import "ARTRealtimeWrapperSDKProxy+Private.h"
 #import "ARTWrapperProxyOptions.h"
 #import "ARTRealtime+Private.h"
+#import "ARTRealtimeChannelOptions.h"
+#import "ARTClientInformation+Private.h"
 
 NS_ASSUME_NONNULL_BEGIN
 
@@ -145,16 +147,29 @@ - (void)release:(nonnull NSString *)name callback:(nullable ARTCallback)errorInf
     [self.channels release:name callback:errorInfo];
 }
 
+- (ARTRealtimeChannelOptions *)addingAgentToOptions:(ARTRealtimeChannelOptions *)options {
+    NSMutableDictionary<NSString *, NSString *> *resolvedParams = options.params ? [options.params mutableCopy] : [NSMutableDictionary dictionary];
+    if (self.options.agents) {
+        resolvedParams[@"agent"] = [ARTClientInformation agentIdentifierForAgents:self.options.agents];
+    }
+
+    ARTRealtimeChannelOptions *resolvedOptions = options ? [options copy] : [[ARTRealtimeChannelOptions alloc] init];
+    resolvedOptions.params = resolvedParams;
+
+    return resolvedOptions;
+}
+
 - (ARTRealtimeWrapperSDKChannelProxy *)get:(NSString *)name {
-    ARTRealtimeChannel *channel = [self.channels get:name];
+    ARTRealtimeChannel *channel = [self.channels get:name
+                                             options:[self addingAgentToOptions:nil]];
     // TODO reuse existing instance
     return [[ARTRealtimeWrapperSDKChannelProxy alloc] initWithChannel:channel
                                                               options:self.options];
 }
 
 - (ARTRealtimeWrapperSDKChannelProxy *)get:(NSString *)name options:(ARTRealtimeChannelOptions *)options {
     ARTRealtimeChannel *channel = [self.channels get:name
-                                             options:options];
+                                             options:[self addingAgentToOptions:options]];
     // TODO reuse existing instance
     return [[ARTRealtimeWrapperSDKChannelProxy alloc] initWithChannel:channel
                                                               options:self.options];

Source/PrivateHeaders/Ably/ARTClientInformation+Private.h

@@ -9,6 +9,9 @@ extern NSString *const ARTClientInformation_libraryVersion;
 + (NSString *)libraryAgentIdentifier;
 + (NSString *)platformAgentIdentifier;
 
+// The resulting string only includes the given agents; it does not insert any default agents.
++ (NSString *)agentIdentifierForAgents:(NSDictionary<NSString *, NSString*> *)agents;
+
 @end
 
 NS_ASSUME_NONNULL_END