feat(realtime): add presence-enabled flag to join push (#736)

* feat(realtime): add presence-enabled flag to join push

- Add presenceEnabled property to RealtimeJoinConfig
- Update CallbackManager to handle presence-enabled joins
- Modify RealtimeChannelV2 to support presence-enabled configuration
- Add tests for presence-enabled functionality
- Update .gitignore for new test artifacts

This change allows developers to explicitly enable/disable presence
functionality when joining realtime channels, providing better control
over presence behavior in realtime subscriptions.

* test(realtime): add test for presence enabled flag during subscribe

- Add comprehensive test that verifies presence.enabled is set to true when presence callback exists
- Test uses FakeWebSocket to simulate real subscription flow
- Verifies that presence enabled flag is correctly set in phx_join payload
- Ensures proper cleanup of subscriptions and connections

This test validates the core functionality where presence enabled is automatically set based on presence callback existence.

* fix(realtime): resubscribe channel when presence callback added to subscribed channel

When a presence callback is added to an already subscribed channel, the channel now automatically resubscribes to ensure the presence functionality works correctly. This fixes an issue where presence callbacks added after subscription would not receive presence updates.

- Add resubscription logic in onPresenceChange method
- Log debug message when resubscribing
- Maintain existing callback registration behavior

Author: Guilherme Souza

.gitignore

@@ -101,3 +101,5 @@ iOSInjectionProject/
 Secrets.swift
 lcov.info
 temp_coverage
+
+.cursor

Sources/Realtime/CallbackManager.swift

@@ -204,4 +204,12 @@ enum RealtimeCallback {
     case let .system(callback): callback.id
     }
   }
+
+  var isPresence: Bool {
+    if case .presence = self {
+      return true
+    } else {
+      return false
+    }
+  }
 }

Sources/Realtime/RealtimeChannelV2.swift

@@ -35,7 +35,9 @@ public final class RealtimeChannelV2: Sendable {
   private var mutableState = MutableState()
 
   let topic: String
-  let config: RealtimeChannelConfig
+
+  @MainActor var config: RealtimeChannelConfig
+
   let logger: (any SupabaseLogger)?
   let socket: RealtimeClientV2
 
@@ -97,6 +99,8 @@ public final class RealtimeChannelV2: Sendable {
     status = .subscribing
     logger?.debug("Subscribing to channel \(topic)")
 
+    config.presence.enabled = callbackManager.callbacks.contains(where: { $0.isPresence })
+
     let joinConfig = RealtimeJoinConfig(
       broadcast: config.broadcast,
       presence: config.presence,
@@ -168,6 +172,7 @@ public final class RealtimeChannelV2: Sendable {
   /// - Parameters:
   ///   - event: Broadcast message event.
   ///   - message: Message payload.
+  @MainActor
   public func broadcast(event: String, message: JSONObject) async {
     if status != .subscribed {
       struct Message: Encodable {
@@ -374,7 +379,7 @@ public final class RealtimeChannelV2: Sendable {
         status = .unsubscribed
 
       case .error:
-        logger?.debug(
+        logger?.error(
           "Received an error in channel \(message.topic). That could be as a result of an invalid access token"
         )
 
@@ -396,7 +401,18 @@ public final class RealtimeChannelV2: Sendable {
   public func onPresenceChange(
     _ callback: @escaping @Sendable (any PresenceAction) -> Void
   ) -> RealtimeSubscription {
+    if status == .subscribed {
+      logger?.debug(
+        "Resubscribe to \(self.topic) due to change in presence callback on joined channel."
+      )
+      Task {
+        await unsubscribe()
+        await subscribe()
+      }
+    }
+
     let id = callbackManager.addPresenceCallback(callback: callback)
+
     return RealtimeSubscription { [weak callbackManager, logger] in
       logger?.debug("Removing presence callback with id: \(id)")
       callbackManager?.removeCallback(id: id)

Sources/Realtime/RealtimeJoinConfig.swift

@@ -50,6 +50,7 @@ public struct BroadcastJoinConfig: Codable, Hashable, Sendable {
 public struct PresenceJoinConfig: Codable, Hashable, Sendable {
   /// Track presence payload across clients.
   public var key: String = ""
+  var enabled: Bool = false
 }
 
 public enum PostgresChangeEvent: String, Codable, Sendable {

Tests/RealtimeTests/RealtimeChannelTests.swift

@@ -6,6 +6,7 @@
 //
 
 import InlineSnapshotTesting
+import TestHelpers
 import XCTest
 import XCTestDynamicOverlay
 
@@ -128,4 +129,67 @@ final class RealtimeChannelTests: XCTestCase {
       """
     }
   }
+
+  @MainActor
+  func testPresenceEnabledDuringSubscribe() async {
+    // Create fake WebSocket for testing
+    let (client, server) = FakeWebSocket.fakes()
+
+    let socket = RealtimeClientV2(
+      url: URL(string: "https://localhost:54321/realtime/v1")!,
+      options: RealtimeClientOptions(
+        headers: ["apikey": "test-key"],
+        accessToken: { "test-token" }
+      ),
+      wsTransport: { _, _ in client },
+      http: HTTPClientMock()
+    )
+
+    // Create a channel without presence callback initially
+    let channel = socket.channel("test-topic")
+
+    // Initially presence should be disabled
+    XCTAssertFalse(channel.config.presence.enabled)
+
+    // Connect the socket
+    await socket.connect()
+
+    // Add a presence callback before subscribing
+    let presenceSubscription = channel.onPresenceChange { _ in }
+
+    // Verify that presence callback exists
+    XCTAssertTrue(channel.callbackManager.callbacks.contains(where: { $0.isPresence }))
+
+    // Start subscription process
+    Task {
+      await channel.subscribe()
+    }
+
+    // Wait for the join message to be sent
+    await Task.megaYield()
+
+    // Check the sent events to verify presence enabled is set correctly
+    let joinEvents = server.receivedEvents.compactMap { $0.realtimeMessage }.filter {
+      $0.event == "phx_join"
+    }
+
+    // Should have at least one join event
+    XCTAssertGreaterThan(joinEvents.count, 0)
+
+    // Check that the presence enabled flag is set to true in the join payload
+    if let joinEvent = joinEvents.first,
+      let config = joinEvent.payload["config"]?.objectValue,
+      let presence = config["presence"]?.objectValue,
+      let enabled = presence["enabled"]?.boolValue
+    {
+      XCTAssertTrue(enabled, "Presence should be enabled when presence callback exists")
+    } else {
+      XCTFail("Could not find presence enabled flag in join payload")
+    }
+
+    // Clean up
+    presenceSubscription.cancel()
+    await channel.unsubscribe()
+    socket.disconnect()
+  }
 }

Tests/RealtimeTests/RealtimeTests.swift

@@ -169,6 +169,7 @@ final class RealtimeTests: XCTestCase {
                   }
                 ],
                 "presence" : {
+                  "enabled" : false,
                   "key" : ""
                 },
                 "private" : false
@@ -241,6 +242,7 @@ final class RealtimeTests: XCTestCase {
 
               ],
               "presence" : {
+                "enabled" : false,
                 "key" : ""
               },
               "private" : false
@@ -264,6 +266,7 @@ final class RealtimeTests: XCTestCase {
 
               ],
               "presence" : {
+                "enabled" : false,
                 "key" : ""
               },
               "private" : false