diff --git a/Examples/ProductSample/Data/AuthenticationRepository.swift b/Examples/ProductSample/Data/AuthenticationRepository.swift
index c96369b2..5dcbd42a 100644
--- a/Examples/ProductSample/Data/AuthenticationRepository.swift
+++ b/Examples/ProductSample/Data/AuthenticationRepository.swift
@@ -28,8 +28,9 @@ struct AuthenticationRepositoryImpl: AuthenticationRepository {
   }
 
   func authStateListener() async -> AsyncStream<AuthenticationState> {
-    await client.onAuthStateChange().compactMap { event in
+    await client.onAuthStateChange().compactMap { event, session in
       switch event {
+      case .initialSession: session != nil ? AuthenticationState.signedIn : .signedOut
       case .signedIn: AuthenticationState.signedIn
       case .signedOut: AuthenticationState.signedOut
       case .passwordRecovery, .tokenRefreshed, .userUpdated, .userDeleted, .mfaChallengeVerified:
diff --git a/Sources/GoTrue/GoTrueClient.swift b/Sources/GoTrue/GoTrueClient.swift
index 1d7b8537..ff42ab4c 100644
--- a/Sources/GoTrue/GoTrueClient.swift
+++ b/Sources/GoTrue/GoTrueClient.swift
@@ -8,9 +8,11 @@ public typealias AnyJSON = _Helpers.AnyJSON
 #endif
 
 public actor GoTrueClient {
+  /// FetchHandler is a type alias for asynchronous network request handling.
   public typealias FetchHandler =
     @Sendable (_ request: URLRequest) async throws -> (Data, URLResponse)
 
+  /// Configuration struct represents the client configuration.
   public struct Configuration: Sendable {
     public let url: URL
     public var headers: [String: String]
@@ -20,6 +22,17 @@ public actor GoTrueClient {
     public let decoder: JSONDecoder
     public let fetch: FetchHandler
 
+    /// Initializes a GoTrueClient Configuration with optional parameters.
+    ///
+    /// - Parameters:
+    ///   - url: The base URL of the GoTrue server.
+    ///   - headers: (Optional) Custom headers to be included in requests.
+    ///   - flowType: (Optional) The authentication flow type. Default is `.implicit`.
+    ///   - localStorage: (Optional) The storage mechanism for local data. Default is a
+    /// KeychainLocalStorage.
+    ///   - encoder: (Optional) The JSON encoder to use for encoding requests.
+    ///   - decoder: (Optional) The JSON decoder to use for decoding responses.
+    ///   - fetch: (Optional) The asynchronous fetch handler for network requests.
     public init(
       url: URL,
       headers: [String: String] = [:],
@@ -81,6 +94,17 @@ public actor GoTrueClient {
   /// Namespace for accessing multi-factor authentication API.
   public let mfa: GoTrueMFA
 
+  /// Initializes a GoTrueClient with optional parameters.
+  ///
+  /// - Parameters:
+  ///   - url: The base URL of the GoTrue server.
+  ///   - headers: (Optional) Custom headers to be included in requests.
+  ///   - flowType: (Optional) The authentication flow type. Default is `.implicit`.
+  ///   - localStorage: (Optional) The storage mechanism for local data. Default is a
+  /// KeychainLocalStorage.
+  ///   - encoder: (Optional) The JSON encoder to use for encoding requests.
+  ///   - decoder: (Optional) The JSON decoder to use for decoding responses.
+  ///   - fetch: (Optional) The asynchronous fetch handler for network requests.
   public init(
     url: URL,
     headers: [String: String] = [:],
@@ -103,6 +127,10 @@ public actor GoTrueClient {
     )
   }
 
+  /// Initializes a GoTrueClient with a specific configuration.
+  ///
+  /// - Parameters:
+  ///   - configuration: The client configuration.
   public init(configuration: Configuration) {
     let api = APIClient()
 
@@ -144,12 +172,13 @@ public actor GoTrueClient {
     )
   }
 
-  public func onAuthStateChange() async -> AsyncStream<AuthChangeEvent> {
+  /// Listen for auth state changes.
+  ///
+  /// An `.initialSession` is always emitted when this method is called.
+  public func onAuthStateChange() async -> AsyncStream<(event: AuthChangeEvent, session: Session?)> {
     let (id, stream) = await eventEmitter.attachListener()
 
     Task { [id] in
-      _debug("emitInitialSessionTask start")
-      defer { _debug("emitInitialSessionTask end") }
       await emitInitialSession(forStreamWithID: id)
     }
 
@@ -192,25 +221,6 @@ public actor GoTrueClient {
     )
   }
 
-  private func prepareForPKCE() -> (codeChallenge: String?, codeChallengeMethod: String?) {
-    if configuration.flowType == .pkce {
-      let codeVerifier = PKCE.generateCodeVerifier()
-
-      do {
-        try codeVerifierStorage.storeCodeVerifier(codeVerifier)
-      } catch {
-        _debug("Error storing code verifier: \(error)")
-      }
-
-      let codeChallenge = PKCE.generateCodeChallenge(from: codeVerifier)
-      let codeChallengeMethod = codeVerifier == codeChallenge ? "plain" : "s256"
-
-      return (codeChallenge, codeChallengeMethod)
-    }
-
-    return (nil, nil)
-  }
-
   /// Creates a new user.
   /// - Parameters:
   ///   - phone: User's phone number with international prefix.
@@ -248,7 +258,7 @@ public actor GoTrueClient {
 
     if let session = response.session {
       try await sessionManager.update(session)
-      await eventEmitter.emit(.signedIn)
+      await eventEmitter.emit(.signedIn, session: session)
     }
 
     return response
@@ -308,7 +318,7 @@ public actor GoTrueClient {
 
     if session.user.emailConfirmedAt != nil || session.user.confirmedAt != nil {
       try await sessionManager.update(session)
-      await eventEmitter.emit(.signedIn)
+      await eventEmitter.emit(.signedIn, session: session)
     }
 
     return session
@@ -411,7 +421,7 @@ public actor GoTrueClient {
       try codeVerifierStorage.deleteCodeVerifier()
 
       try await sessionManager.update(session)
-      await eventEmitter.emit(.signedIn)
+      await eventEmitter.emit(.signedIn, session: session)
 
       return session
     } catch {
@@ -524,10 +534,10 @@ public actor GoTrueClient {
     )
 
     try await sessionManager.update(session)
-    await eventEmitter.emit(.signedIn)
+    await eventEmitter.emit(.signedIn, session: session)
 
     if let type = params.first(where: { $0.name == "type" })?.value, type == "recovery" {
-      await eventEmitter.emit(.passwordRecovery)
+      await eventEmitter.emit(.passwordRecovery, session: session)
     }
 
     return session
@@ -571,7 +581,7 @@ public actor GoTrueClient {
     }
 
     try await sessionManager.update(session)
-    await eventEmitter.emit(.signedIn)
+    await eventEmitter.emit(.signedIn, session: session)
     return session
   }
 
@@ -586,9 +596,9 @@ public actor GoTrueClient {
         )
       )
       await sessionManager.remove()
-      await eventEmitter.emit(.signedOut)
+      await eventEmitter.emit(.signedOut, session: nil)
     } catch {
-      await eventEmitter.emit(.signedOut)
+      await eventEmitter.emit(.signedOut, session: nil)
       throw error
     }
   }
@@ -662,7 +672,7 @@ public actor GoTrueClient {
 
     if let session = response.session {
       try await sessionManager.update(session)
-      await eventEmitter.emit(.signedIn)
+      await eventEmitter.emit(.signedIn, session: session)
     }
 
     return response
@@ -702,7 +712,7 @@ public actor GoTrueClient {
     ).decoded(as: User.self, decoder: configuration.decoder)
     session.user = updatedUser
     try await sessionManager.update(session)
-    await eventEmitter.emit(.userUpdated)
+    await eventEmitter.emit(.userUpdated, session: session)
     return updatedUser
   }
 
@@ -733,14 +743,24 @@ public actor GoTrueClient {
     )
   }
 
+  /// Refresh and return a new session, regardless of expiry status.
+  /// - Parameter refreshToken: The optional refresh token to use for refreshing the session. If
+  /// none is provided then this method tries to load the refresh token from the current session.
+  /// - Returns: A new session.
   @discardableResult
-  public func refreshSession(refreshToken: String) async throws -> Session {
+  public func refreshSession(refreshToken: String? = nil) async throws -> Session {
+    var credentials = UserCredentials(refreshToken: refreshToken)
+    if credentials.refreshToken == nil {
+      credentials.refreshToken = try await sessionManager.session(shouldValidateExpiration: false)
+        .refreshToken
+    }
+
     let session = try await api.execute(
       .init(
         path: "/token",
         method: "POST",
         query: [URLQueryItem(name: "grant_type", value: "refresh_token")],
-        body: configuration.encoder.encode(UserCredentials(refreshToken: refreshToken))
+        body: configuration.encoder.encode(credentials)
       )
     ).decoded(as: Session.self, decoder: configuration.decoder)
 
@@ -749,33 +769,41 @@ public actor GoTrueClient {
       .user.confirmedAt != nil
     {
       try await sessionManager.update(session)
-      await eventEmitter.emit(.tokenRefreshed)
+      await eventEmitter.emit(.tokenRefreshed, session: session)
     }
 
     return session
   }
 
-  /// Refresh and return a new session, regardless of expiry status.
-  @discardableResult
-  public func refreshSession() async throws -> Session {
-    let refreshToken = try await session.refreshToken
-    return try await refreshSession(refreshToken: refreshToken)
-  }
-
   private func emitInitialSession(forStreamWithID id: UUID) async {
-    _debug("start")
-    defer { _debug("end") }
-
     let session = try? await session
-    await eventEmitter.emit(session != nil ? .signedIn : .signedOut, id)
+    await eventEmitter.emit(.initialSession, session, id)
   }
 
-  private func _debug(
-    _ message: String,
-    function: StaticString = #function,
-    line: UInt = #line
-  ) {
-    debugPrint("[GoTrueClient] \(function):\(line) \(message)")
+  private func prepareForPKCE() -> (codeChallenge: String?, codeChallengeMethod: String?) {
+    if configuration.flowType == .pkce {
+      let codeVerifier = PKCE.generateCodeVerifier()
+
+      do {
+        try codeVerifierStorage.storeCodeVerifier(codeVerifier)
+      } catch {
+        assertionFailure(
+          """
+          An error occurred while storing the code verifier,
+          PKCE flow may not work as expected.
+
+          Error: \(error.localizedDescription)
+          """
+        )
+      }
+
+      let codeChallenge = PKCE.generateCodeChallenge(from: codeVerifier)
+      let codeChallengeMethod = codeVerifier == codeChallenge ? "plain" : "s256"
+
+      return (codeChallenge, codeChallengeMethod)
+    }
+
+    return (nil, nil)
   }
 
   private func isImplicitGrantFlow(url: URL) -> Bool {
@@ -793,6 +821,7 @@ public actor GoTrueClient {
 }
 
 extension GoTrueClient {
+  /// Notification posted when an auth state event is triggered.
   public static let didChangeAuthStateNotification = Notification.Name(
     "DID_CHANGE_AUTH_STATE_NOTIFICATION"
   )
diff --git a/Sources/GoTrue/GoTrueMFA.swift b/Sources/GoTrue/GoTrueMFA.swift
index aa329464..7f224fdc 100644
--- a/Sources/GoTrue/GoTrueMFA.swift
+++ b/Sources/GoTrue/GoTrueMFA.swift
@@ -66,7 +66,7 @@ public actor GoTrueMFA {
 
     try await sessionManager.update(response)
 
-    await eventEmitter.emit(.mfaChallengeVerified)
+    await eventEmitter.emit(.mfaChallengeVerified, session: response)
 
     return response
   }
diff --git a/Sources/GoTrue/Internal/EventEmitter.swift b/Sources/GoTrue/Internal/EventEmitter.swift
index 629e6c20..6534fc9d 100644
--- a/Sources/GoTrue/Internal/EventEmitter.swift
+++ b/Sources/GoTrue/Internal/EventEmitter.swift
@@ -2,25 +2,25 @@ import Foundation
 @_spi(Internal) import _Helpers
 
 struct EventEmitter: Sendable {
-  var attachListener: @Sendable () async -> (id: UUID, stream: AsyncStream<AuthChangeEvent>)
-  var emit: @Sendable (_ event: AuthChangeEvent, _ id: UUID?) async -> Void
+  var attachListener: @Sendable () async -> (id: UUID, stream: AsyncStream<(event: AuthChangeEvent, session: Session?)>)
+  var emit: @Sendable (_ event: AuthChangeEvent, _ session: Session?, _ id: UUID?) async -> Void
 }
 
 extension EventEmitter {
-  func emit(_ event: AuthChangeEvent) async {
-    await emit(event, nil)
+  func emit(_ event: AuthChangeEvent, session: Session?) async {
+    await emit(event, session, nil)
   }
 }
 
 extension EventEmitter {
   static var live: Self = {
-    let continuations = ActorIsolated([UUID: AsyncStream<AuthChangeEvent>.Continuation]())
+    let continuations = ActorIsolated([UUID: AsyncStream<(event: AuthChangeEvent, session: Session?)>.Continuation]())
 
     return Self(
       attachListener: {
         let id = UUID()
 
-        let (stream, continuation) = AsyncStream<AuthChangeEvent>.makeStream()
+        let (stream, continuation) = AsyncStream<(event: AuthChangeEvent, session: Session?)>.makeStream()
 
         continuation.onTermination = { [id] _ in
           continuations.withValue {
@@ -34,12 +34,16 @@ extension EventEmitter {
 
         return (id, stream)
       },
-      emit: { event, id in
+      emit: { event, session, id in
+        NotificationCenter.default.post(
+          name: GoTrueClient.didChangeAuthStateNotification,
+          object: nil
+        )
         if let id {
-          continuations.value[id]?.yield(event)
+          continuations.value[id]?.yield((event, session))
         } else {
           for continuation in continuations.value.values {
-            continuation.yield(event)
+            continuation.yield((event, session))
           }
         }
       }
diff --git a/Sources/GoTrue/Internal/SessionManager.swift b/Sources/GoTrue/Internal/SessionManager.swift
index a8cf9bf3..06b1b090 100644
--- a/Sources/GoTrue/Internal/SessionManager.swift
+++ b/Sources/GoTrue/Internal/SessionManager.swift
@@ -7,16 +7,20 @@ struct SessionRefresher: Sendable {
 }
 
 struct SessionManager: Sendable {
-  var session: @Sendable () async throws -> Session
+  var session: @Sendable (_ shouldValidateExpiration: Bool) async throws -> Session
   var update: @Sendable (_ session: Session) async throws -> Void
   var remove: @Sendable () async -> Void
+
+  func session(shouldValidateExpiration: Bool = true) async throws -> Session {
+    try await session(shouldValidateExpiration)
+  }
 }
 
 extension SessionManager {
   static var live: Self = {
     let manager = _LiveSessionManager()
     return Self(
-      session: { try await manager.session() },
+      session: { try await manager.session(shouldValidateExpiration: $0) },
       update: { try await manager.update($0) },
       remove: { await manager.remove() }
     )
@@ -34,7 +38,7 @@ actor _LiveSessionManager {
     Dependencies.current.value!.sessionRefresher
   }
 
-  func session() async throws -> Session {
+  func session(shouldValidateExpiration: Bool) async throws -> Session {
     if let task {
       return try await task.value
     }
@@ -43,7 +47,7 @@ actor _LiveSessionManager {
       throw GoTrueError.sessionNotFound
     }
 
-    if currentSession.isValid {
+    if currentSession.isValid || !shouldValidateExpiration {
       return currentSession.session
     }
 
diff --git a/Sources/GoTrue/Types.swift b/Sources/GoTrue/Types.swift
index 9f75aa1f..68d98b52 100644
--- a/Sources/GoTrue/Types.swift
+++ b/Sources/GoTrue/Types.swift
@@ -1,6 +1,7 @@
 import Foundation
 
 public enum AuthChangeEvent: String, Sendable {
+  case initialSession = "INITIAL_SESSION"
   case passwordRecovery = "PASSWORD_RECOVERY"
   case signedIn = "SIGNED_IN"
   case signedOut = "SIGNED_OUT"
diff --git a/Sources/Supabase/SupabaseClient.swift b/Sources/Supabase/SupabaseClient.swift
index 15cd9596..8017dcc5 100644
--- a/Sources/Supabase/SupabaseClient.swift
+++ b/Sources/Supabase/SupabaseClient.swift
@@ -61,6 +61,12 @@ public final class SupabaseClient {
   }
 
   /// Create a new client.
+  /// - Parameters:
+  ///   - supabaseURL: The unique Supabase URL which is supplied when you create a new project in
+  /// your project dashboard.
+  ///   - supabaseKey: The unique Supabase Key which is supplied when you create a new project in
+  /// your project dashboard.
+  ///   - options: Custom options to configure client's behavior.
   public init(
     supabaseURL: URL,
     supabaseKey: String,
@@ -85,7 +91,11 @@ public final class SupabaseClient {
       url: supabaseURL.appendingPathComponent("/auth/v1"),
       headers: defaultHeaders,
       flowType: options.auth.flowType,
-      localStorage: options.auth.storage
+      localStorage: options.auth.storage,
+      fetch: {
+        // DON'T use `fetchWithAuth` method within the GoTrueClient as it may cause a deadlock.
+        try await options.global.session.data(for: $0)
+      }
     )
 
     listenForAuthEvents()
@@ -118,8 +128,7 @@ public final class SupabaseClient {
 
   private func listenForAuthEvents() {
     listenForAuthEventsTask = Task {
-      for await event in await auth.onAuthStateChange() {
-        let session = try? await auth.session
+      for await (event, session) in await auth.onAuthStateChange() {
         handleTokenChanged(event: event, session: session)
       }
     }
diff --git a/Sources/Supabase/Types.swift b/Sources/Supabase/Types.swift
index ecafd48a..f38ef31f 100644
--- a/Sources/Supabase/Types.swift
+++ b/Sources/Supabase/Types.swift
@@ -31,7 +31,10 @@ public struct SupabaseClientOptions: Sendable {
   }
 
   public struct GlobalOptions: Sendable {
+    /// Optional headers for initializing the client, it will be passed down to all sub-clients.
     public let headers: [String: String]
+
+    /// A session to use for making requests, defaults to `URLSession.shared`.
     public let session: URLSession
 
     public init(headers: [String: String] = [:], session: URLSession = .shared) {
diff --git a/Tests/GoTrueTests/GoTrueClientTests.swift b/Tests/GoTrueTests/GoTrueClientTests.swift
index c782524b..c1f6b7e3 100644
--- a/Tests/GoTrueTests/GoTrueClientTests.swift
+++ b/Tests/GoTrueTests/GoTrueClientTests.swift
@@ -22,12 +22,12 @@ final class GoTrueClientTests: XCTestCase {
 
     await withDependencies {
       $0.eventEmitter = .live
-      $0.sessionManager.session = { session }
+      $0.sessionManager.session = { @Sendable _ in session }
     } operation: {
       let authStateStream = await sut.onAuthStateChange()
 
       let streamTask = Task {
-        for await event in authStateStream {
+        for await (event, _) in authStateStream {
           events.withValue {
             $0.append(event)
           }
@@ -38,7 +38,7 @@ final class GoTrueClientTests: XCTestCase {
 
       await fulfillment(of: [expectation])
 
-      XCTAssertEqual(events.value, [.signedIn])
+      XCTAssertEqual(events.value, [.initialSession])
 
       streamTask.cancel()
     }
diff --git a/Tests/GoTrueTests/Mocks/Mocks.swift b/Tests/GoTrueTests/Mocks/Mocks.swift
index 4d6f52a6..05f3c073 100644
--- a/Tests/GoTrueTests/Mocks/Mocks.swift
+++ b/Tests/GoTrueTests/Mocks/Mocks.swift
@@ -37,7 +37,7 @@ extension EventEmitter {
 
   static let noop = Self(
     attachListener: { (UUID(), AsyncStream.makeStream().stream) },
-    emit: { _, _ in }
+    emit: { _, _, _ in }
   )
 }
 
diff --git a/Tests/GoTrueTests/RequestsTests.swift b/Tests/GoTrueTests/RequestsTests.swift
index 8e27eb27..a6c3389f 100644
--- a/Tests/GoTrueTests/RequestsTests.swift
+++ b/Tests/GoTrueTests/RequestsTests.swift
@@ -214,7 +214,7 @@ final class RequestsTests: XCTestCase {
     let sut = makeSUT()
 
     await withDependencies {
-      $0.sessionManager.session = {
+      $0.sessionManager.session = { @Sendable _ in
         .validSession
       }
     } operation: {
@@ -241,7 +241,7 @@ final class RequestsTests: XCTestCase {
   func testSignOut() async {
     let sut = makeSUT()
     await withDependencies {
-      $0.sessionManager.session = { .validSession }
+      $0.sessionManager.session = { @Sendable _ in .validSession }
       $0.eventEmitter = .noop
     } operation: {
       await assert {
@@ -289,7 +289,7 @@ final class RequestsTests: XCTestCase {
     let sut = makeSUT()
 
     await withDependencies {
-      $0.sessionManager.session = {
+      $0.sessionManager.session = { @Sendable _ in
         .validSession
       }
     } operation: {