From 0eeb7a2ec94b9ac1c4dcb9d21200c79f63a50c71 Mon Sep 17 00:00:00 2001
From: Daymon <daymxn@google.com>
Date: Wed, 9 Jul 2025 12:04:35 -0500
Subject: [PATCH 01/29] Add config support

---
 FirebaseAI/Sources/FirebaseAI.swift           | 37 ++++++++---
 FirebaseAI/Sources/FirebaseAIConfig.swift     | 63 +++++++++++++++++++
 FirebaseAI/Sources/GenerativeAIService.swift  | 24 ++++++-
 FirebaseAI/Sources/GenerativeModel.swift      |  6 +-
 .../Types/Public/Imagen/ImagenModel.swift     |  5 +-
 5 files changed, 121 insertions(+), 14 deletions(-)
 create mode 100644 FirebaseAI/Sources/FirebaseAIConfig.swift

diff --git a/FirebaseAI/Sources/FirebaseAI.swift b/FirebaseAI/Sources/FirebaseAI.swift
index 48f7183d4e6..d7a9db704b1 100644
--- a/FirebaseAI/Sources/FirebaseAI.swift
+++ b/FirebaseAI/Sources/FirebaseAI.swift
@@ -32,13 +32,18 @@ public final class FirebaseAI: Sendable {
   ///     ``FirebaseApp``.
   ///   - backend: The backend API for the Firebase AI SDK; if not specified, uses the default
   ///     ``Backend/googleAI()`` (Gemini Developer API).
+  ///   - config: Configuration options for the Firebase AI SDK that propogate across all models
+  ///     created. Uses default options when not specified, see the ``FirebaseAIConfig``
+  ///     documentation for more information.
   /// - Returns: A `FirebaseAI` instance, configured with the custom `FirebaseApp`.
   public static func firebaseAI(app: FirebaseApp? = nil,
-                                backend: Backend = .googleAI()) -> FirebaseAI {
+                                backend: Backend = .googleAI(),
+                                config: FirebaseAIConfig = FirebaseAIConfig()) -> FirebaseAI {
     let instance = createInstance(
       app: app,
       location: backend.location,
-      apiConfig: backend.apiConfig
+      apiConfig: backend.apiConfig,
+      aiConfig: config
     )
     // Verify that the `FirebaseAI` instance is always configured with the production endpoint since
     // this is the public API surface for creating an instance.
@@ -90,7 +95,8 @@ public final class FirebaseAI: Sendable {
       tools: tools,
       toolConfig: toolConfig,
       systemInstruction: systemInstruction,
-      requestOptions: requestOptions
+      requestOptions: requestOptions,
+      aiConfig: aiConfig
     )
   }
 
@@ -126,7 +132,8 @@ public final class FirebaseAI: Sendable {
       apiConfig: apiConfig,
       generationConfig: generationConfig,
       safetySettings: safetySettings,
-      requestOptions: requestOptions
+      requestOptions: requestOptions,
+      aiConfig: aiConfig
     )
   }
 
@@ -141,6 +148,8 @@ public final class FirebaseAI: Sendable {
 
   let apiConfig: APIConfig
 
+  let aiConfig: FirebaseAIConfig
+
   /// A map of active `FirebaseAI` instances keyed by the `FirebaseApp` name and the `location`,
   /// in the format `appName:location`.
   private nonisolated(unsafe) static var instances: [InstanceKey: FirebaseAI] = [:]
@@ -156,7 +165,7 @@ public final class FirebaseAI: Sendable {
   )
 
   static func createInstance(app: FirebaseApp?, location: String?,
-                             apiConfig: APIConfig) -> FirebaseAI {
+                             apiConfig: APIConfig, aiConfig: FirebaseAIConfig) -> FirebaseAI {
     guard let app = app ?? FirebaseApp.app() else {
       fatalError("No instance of the default Firebase app was found.")
     }
@@ -166,16 +175,26 @@ public final class FirebaseAI: Sendable {
     // Unlock before the function returns.
     defer { os_unfair_lock_unlock(&instancesLock) }
 
-    let instanceKey = InstanceKey(appName: app.name, location: location, apiConfig: apiConfig)
+    let instanceKey = InstanceKey(
+      appName: app.name,
+      location: location,
+      apiConfig: apiConfig,
+      aiConfig: aiConfig
+    )
     if let instance = instances[instanceKey] {
       return instance
     }
-    let newInstance = FirebaseAI(app: app, location: location, apiConfig: apiConfig)
+    let newInstance = FirebaseAI(
+      app: app,
+      location: location,
+      apiConfig: apiConfig,
+      aiConfig: aiConfig
+    )
     instances[instanceKey] = newInstance
     return newInstance
   }
 
-  init(app: FirebaseApp, location: String?, apiConfig: APIConfig) {
+  init(app: FirebaseApp, location: String?, apiConfig: APIConfig, aiConfig: FirebaseAIConfig) {
     guard let projectID = app.options.projectID else {
       fatalError("The Firebase app named \"\(app.name)\" has no project ID in its configuration.")
     }
@@ -195,6 +214,7 @@ public final class FirebaseAI: Sendable {
     )
     self.apiConfig = apiConfig
     self.location = location
+    self.aiConfig = aiConfig
   }
 
   func modelResourceName(modelName: String) -> String {
@@ -249,5 +269,6 @@ public final class FirebaseAI: Sendable {
     let appName: String
     let location: String?
     let apiConfig: APIConfig
+    let aiConfig: FirebaseAIConfig
   }
 }
diff --git a/FirebaseAI/Sources/FirebaseAIConfig.swift b/FirebaseAI/Sources/FirebaseAIConfig.swift
new file mode 100644
index 00000000000..31d2fda2f5b
--- /dev/null
+++ b/FirebaseAI/Sources/FirebaseAIConfig.swift
@@ -0,0 +1,63 @@
+// Copyright 2025 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+/// Configuration options for ``FirebaseAI``, which persists across all models.
+@available(iOS 15.0, macOS 12.0, macCatalyst 15.0, tvOS 15.0, watchOS 8.0, *)
+public struct FirebaseAIConfig: Sendable, Hashable, Encodable {
+  /// Options for App Check specific behavior within a ``FirebaseAI`` instance.
+  let appCheck: AppCheckOptions
+
+  /// Creates a new ``FirebaseAI`` value.
+  ///
+  /// - Parameters:
+  ///   - appCheck: Optionally configure certain behavior with how App Check is used.
+  public init(appCheck: AppCheckOptions = AppCheckOptions()) {
+    self.appCheck = appCheck
+  }
+}
+
+/// Configurable options for how App Check is used within a ``FirebaseAI`` instance.
+///
+/// Can be set when creating a ``FirebaseAIConfig``.
+@available(iOS 15.0, macOS 12.0, macCatalyst 15.0, tvOS 15.0, watchOS 8.0, *)
+public struct AppCheckOptions: Sendable, Hashable, Encodable {
+  /// Use `limitedUseTokens`, instead of the standard cached tokens, when sending requests
+  /// to the backend.
+  let requireLimitedUseTokens: Bool
+
+  /// Creates a new ``AppCheckOptions`` value.
+  ///
+  /// - Parameters:
+  ///   - requiredLimitedUseTokens: When sending tokens to the backend, this option enables
+  ///     the usage of App Check's `limitedUseTokens` instead of the standard cached tokens.
+  ///
+  ///     A new `limitedUseToken` will be generated for each request; providing a lower attack
+  ///     surface for malicious parties to hijack tokens. When used alongside [replay protection](https://firebase.google.com/docs/app-check/custom-resource-backend#replay-protection),
+  ///     `limitedUseTokens` are also _consumed_ after each request, ensuring they can't be used
+  ///     again.
+  ///
+  ///     _To prevent breakage, this flag is set to `false` by default._
+  ///
+  ///     > Important: Replay protection is not currently supported for the FirebaseAI backend.
+  ///     > While this feature is being developed, you can still migrate to using `limitedUseTokens`.
+  ///     > Because `limitedUseTokens` are backwards compatable, you can still use them without replay
+  ///     > protection. Due to their shorter TTL over standard App Check tokens, they still provide a
+  ///     > security benefit.
+  ///     >
+  ///     > Migrating to `limitedUseTokens` ahead of time will also allow you to enable replay
+  ///     > protection down the road (when support is added), without breaking your users.
+  public init(requiredLimitedUseTokens: Bool = false) {
+    requireLimitedUseTokens = requiredLimitedUseTokens
+  }
+}
diff --git a/FirebaseAI/Sources/GenerativeAIService.swift b/FirebaseAI/Sources/GenerativeAIService.swift
index e1538af997f..f63f2869d4e 100644
--- a/FirebaseAI/Sources/GenerativeAIService.swift
+++ b/FirebaseAI/Sources/GenerativeAIService.swift
@@ -30,9 +30,12 @@ struct GenerativeAIService {
 
   private let urlSession: URLSession
 
-  init(firebaseInfo: FirebaseInfo, urlSession: URLSession) {
+  private let aiConfig: FirebaseAIConfig
+
+  init(firebaseInfo: FirebaseInfo, urlSession: URLSession, aiConfig: FirebaseAIConfig) {
     self.firebaseInfo = firebaseInfo
     self.urlSession = urlSession
+    self.aiConfig = aiConfig
   }
 
   func loadRequest<T: GenerativeAIRequest>(request: T) async throws -> T.Response {
@@ -177,7 +180,7 @@ struct GenerativeAIService {
     urlRequest.setValue("application/json", forHTTPHeaderField: "Content-Type")
 
     if let appCheck = firebaseInfo.appCheck {
-      let tokenResult = await appCheck.getToken(forcingRefresh: false)
+      let tokenResult = await fetchAppCheckToken(appCheck: appCheck)
       urlRequest.setValue(tokenResult.token, forHTTPHeaderField: "X-Firebase-AppCheck")
       if let error = tokenResult.error {
         AILog.error(
@@ -207,6 +210,23 @@ struct GenerativeAIService {
     return urlRequest
   }
 
+  private func fetchAppCheckToken(appCheck: AppCheckInterop) async
+    -> FIRAppCheckTokenResultInterop {
+    if aiConfig.appCheck.requireLimitedUseTokens {
+      if let token = await appCheck.getLimitedUseToken?() {
+        return token
+      }
+
+      AILog.error(
+        code: .appCheckTokenFetchFailed,
+        "Missing getLimitedUseToken() function, but requireLimitedUseTokens was enabled."
+      )
+      // falls back to standard token
+    }
+
+    return await appCheck.getToken(forcingRefresh: false)
+  }
+
   private func httpResponse(urlResponse: URLResponse) throws -> HTTPURLResponse {
     // The following condition should always be true: "Whenever you make HTTP URL load requests, any
     // response objects you get back from the URLSession, NSURLConnection, or NSURLDownload class
diff --git a/FirebaseAI/Sources/GenerativeModel.swift b/FirebaseAI/Sources/GenerativeModel.swift
index 8d3f5e043a7..8caa33bcaf7 100644
--- a/FirebaseAI/Sources/GenerativeModel.swift
+++ b/FirebaseAI/Sources/GenerativeModel.swift
@@ -76,6 +76,7 @@ public final class GenerativeModel: Sendable {
   ///     only text content is supported.
   ///   - requestOptions: Configuration parameters for sending requests to the backend.
   ///   - urlSession: The `URLSession` to use for requests; defaults to `URLSession.shared`.
+  ///   - aiConfig: Configuration for various behavior shared across models.
   init(modelName: String,
        modelResourceName: String,
        firebaseInfo: FirebaseInfo,
@@ -86,13 +87,14 @@ public final class GenerativeModel: Sendable {
        toolConfig: ToolConfig? = nil,
        systemInstruction: ModelContent? = nil,
        requestOptions: RequestOptions,
-       urlSession: URLSession = GenAIURLSession.default) {
+       urlSession: URLSession = GenAIURLSession.default, aiConfig: FirebaseAIConfig) {
     self.modelName = modelName
     self.modelResourceName = modelResourceName
     self.apiConfig = apiConfig
     generativeAIService = GenerativeAIService(
       firebaseInfo: firebaseInfo,
-      urlSession: urlSession
+      urlSession: urlSession,
+      aiConfig: aiConfig
     )
     self.generationConfig = generationConfig
     self.safetySettings = safetySettings
diff --git a/FirebaseAI/Sources/Types/Public/Imagen/ImagenModel.swift b/FirebaseAI/Sources/Types/Public/Imagen/ImagenModel.swift
index e6f96df511a..dca91acb3f9 100644
--- a/FirebaseAI/Sources/Types/Public/Imagen/ImagenModel.swift
+++ b/FirebaseAI/Sources/Types/Public/Imagen/ImagenModel.swift
@@ -53,12 +53,13 @@ public final class ImagenModel {
        generationConfig: ImagenGenerationConfig?,
        safetySettings: ImagenSafetySettings?,
        requestOptions: RequestOptions,
-       urlSession: URLSession = GenAIURLSession.default) {
+       urlSession: URLSession = GenAIURLSession.default, aiConfig: FirebaseAIConfig) {
     self.modelResourceName = modelResourceName
     self.apiConfig = apiConfig
     generativeAIService = GenerativeAIService(
       firebaseInfo: firebaseInfo,
-      urlSession: urlSession
+      urlSession: urlSession,
+      aiConfig: aiConfig
     )
     self.generationConfig = generationConfig
     self.safetySettings = safetySettings

From 6c878ff0559e2677a5c25ad00f6d66e51ccdee0c Mon Sep 17 00:00:00 2001
From: Daymon <daymxn@google.com>
Date: Wed, 9 Jul 2025 12:06:19 -0500
Subject: [PATCH 02/29] fmt

---
 FirebaseAI/Sources/FirebaseAIConfig.swift | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/FirebaseAI/Sources/FirebaseAIConfig.swift b/FirebaseAI/Sources/FirebaseAIConfig.swift
index 31d2fda2f5b..f0f2846a121 100644
--- a/FirebaseAI/Sources/FirebaseAIConfig.swift
+++ b/FirebaseAI/Sources/FirebaseAIConfig.swift
@@ -50,10 +50,10 @@ public struct AppCheckOptions: Sendable, Hashable, Encodable {
   ///     _To prevent breakage, this flag is set to `false` by default._
   ///
   ///     > Important: Replay protection is not currently supported for the FirebaseAI backend.
-  ///     > While this feature is being developed, you can still migrate to using `limitedUseTokens`.
-  ///     > Because `limitedUseTokens` are backwards compatable, you can still use them without replay
-  ///     > protection. Due to their shorter TTL over standard App Check tokens, they still provide a
-  ///     > security benefit.
+  ///     > While this feature is being developed, you can still migrate to using
+  ///     > `limitedUseTokens`. Because `limitedUseTokens` are backwards compatable, you can still
+  ///     > use them without replay protection. Due to their shorter TTL over standard App Check
+  ///     > tokens, they still provide a security benefit.
   ///     >
   ///     > Migrating to `limitedUseTokens` ahead of time will also allow you to enable replay
   ///     > protection down the road (when support is added), without breaking your users.

From e6de038fcef32d55c5a36631e828423c052cc33c Mon Sep 17 00:00:00 2001
From: Daymon <daymxn@google.com>
Date: Fri, 11 Jul 2025 12:03:30 -0500
Subject: [PATCH 03/29] Migrate to nested config

---
 ...seAIConfig.swift => AppCheckOptions.swift} | 23 +++------------
 FirebaseAI/Sources/FirebaseAI.swift           | 29 ++++++++++++++-----
 2 files changed, 26 insertions(+), 26 deletions(-)
 rename FirebaseAI/Sources/{FirebaseAIConfig.swift => AppCheckOptions.swift} (72%)

diff --git a/FirebaseAI/Sources/FirebaseAIConfig.swift b/FirebaseAI/Sources/AppCheckOptions.swift
similarity index 72%
rename from FirebaseAI/Sources/FirebaseAIConfig.swift
rename to FirebaseAI/Sources/AppCheckOptions.swift
index f0f2846a121..6411eb39e12 100644
--- a/FirebaseAI/Sources/FirebaseAIConfig.swift
+++ b/FirebaseAI/Sources/AppCheckOptions.swift
@@ -12,24 +12,9 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-/// Configuration options for ``FirebaseAI``, which persists across all models.
-@available(iOS 15.0, macOS 12.0, macCatalyst 15.0, tvOS 15.0, watchOS 8.0, *)
-public struct FirebaseAIConfig: Sendable, Hashable, Encodable {
-  /// Options for App Check specific behavior within a ``FirebaseAI`` instance.
-  let appCheck: AppCheckOptions
-
-  /// Creates a new ``FirebaseAI`` value.
-  ///
-  /// - Parameters:
-  ///   - appCheck: Optionally configure certain behavior with how App Check is used.
-  public init(appCheck: AppCheckOptions = AppCheckOptions()) {
-    self.appCheck = appCheck
-  }
-}
-
 /// Configurable options for how App Check is used within a ``FirebaseAI`` instance.
 ///
-/// Can be set when creating a ``FirebaseAIConfig``.
+/// Can be set when creating a ``FirebaseAI.Config``.
 @available(iOS 15.0, macOS 12.0, macCatalyst 15.0, tvOS 15.0, watchOS 8.0, *)
 public struct AppCheckOptions: Sendable, Hashable, Encodable {
   /// Use `limitedUseTokens`, instead of the standard cached tokens, when sending requests
@@ -39,7 +24,7 @@ public struct AppCheckOptions: Sendable, Hashable, Encodable {
   /// Creates a new ``AppCheckOptions`` value.
   ///
   /// - Parameters:
-  ///   - requiredLimitedUseTokens: When sending tokens to the backend, this option enables
+  ///   - requireLimitedUseTokens: When sending tokens to the backend, this option enables
   ///     the usage of App Check's `limitedUseTokens` instead of the standard cached tokens.
   ///
   ///     A new `limitedUseToken` will be generated for each request; providing a lower attack
@@ -57,7 +42,7 @@ public struct AppCheckOptions: Sendable, Hashable, Encodable {
   ///     >
   ///     > Migrating to `limitedUseTokens` ahead of time will also allow you to enable replay
   ///     > protection down the road (when support is added), without breaking your users.
-  public init(requiredLimitedUseTokens: Bool = false) {
-    requireLimitedUseTokens = requiredLimitedUseTokens
+  public init(requireLimitedUseTokens: Bool = false) {
+    self.requireLimitedUseTokens = requireLimitedUseTokens
   }
 }
diff --git a/FirebaseAI/Sources/FirebaseAI.swift b/FirebaseAI/Sources/FirebaseAI.swift
index d7a9db704b1..18b2653598e 100644
--- a/FirebaseAI/Sources/FirebaseAI.swift
+++ b/FirebaseAI/Sources/FirebaseAI.swift
@@ -33,12 +33,12 @@ public final class FirebaseAI: Sendable {
   ///   - backend: The backend API for the Firebase AI SDK; if not specified, uses the default
   ///     ``Backend/googleAI()`` (Gemini Developer API).
   ///   - config: Configuration options for the Firebase AI SDK that propogate across all models
-  ///     created. Uses default options when not specified, see the ``FirebaseAIConfig``
+  ///     created. Uses default options when not specified, see the ``FirebaseAI.Config``
   ///     documentation for more information.
   /// - Returns: A `FirebaseAI` instance, configured with the custom `FirebaseApp`.
   public static func firebaseAI(app: FirebaseApp? = nil,
                                 backend: Backend = .googleAI(),
-                                config: FirebaseAIConfig = FirebaseAIConfig()) -> FirebaseAI {
+                                config: FirebaseAI.Config = .config(appCheck: AppCheckOptions())) -> FirebaseAI {
     let instance = createInstance(
       app: app,
       location: backend.location,
@@ -140,7 +140,22 @@ public final class FirebaseAI: Sendable {
   /// Class to enable FirebaseAI to register via the Objective-C based Firebase component system
   /// to include FirebaseAI in the userAgent.
   @objc(FIRVertexAIComponent) class FirebaseVertexAIComponent: NSObject {}
-
+  
+  /// Configuration options for ``FirebaseAI``, which persists across all models.
+  @available(iOS 15.0, macOS 12.0, macCatalyst 15.0, tvOS 15.0, watchOS 8.0, *)
+  public struct Config : Sendable, Hashable, Encodable {
+    /// Options for App Check specific behavior within a ``FirebaseAI`` instance.
+    let appCheck: AppCheckOptions
+    
+    /// Creates a new ``FirebaseAI.Config`` value.
+    ///
+    /// - Parameters:
+    ///   - appCheck: Optionally configure certain behavior with how App Check is used.
+    public static func config(appCheck: AppCheckOptions = AppCheckOptions()) -> Config {
+      Config(appCheck: appCheck)
+    }
+  }
+  
   // MARK: - Private
 
   /// Firebase data relevant to Firebase AI.
@@ -148,7 +163,7 @@ public final class FirebaseAI: Sendable {
 
   let apiConfig: APIConfig
 
-  let aiConfig: FirebaseAIConfig
+  let aiConfig: FirebaseAI.Config
 
   /// A map of active `FirebaseAI` instances keyed by the `FirebaseApp` name and the `location`,
   /// in the format `appName:location`.
@@ -165,7 +180,7 @@ public final class FirebaseAI: Sendable {
   )
 
   static func createInstance(app: FirebaseApp?, location: String?,
-                             apiConfig: APIConfig, aiConfig: FirebaseAIConfig) -> FirebaseAI {
+                             apiConfig: APIConfig, aiConfig: FirebaseAI.Config) -> FirebaseAI {
     guard let app = app ?? FirebaseApp.app() else {
       fatalError("No instance of the default Firebase app was found.")
     }
@@ -194,7 +209,7 @@ public final class FirebaseAI: Sendable {
     return newInstance
   }
 
-  init(app: FirebaseApp, location: String?, apiConfig: APIConfig, aiConfig: FirebaseAIConfig) {
+  init(app: FirebaseApp, location: String?, apiConfig: APIConfig, aiConfig: FirebaseAI.Config) {
     guard let projectID = app.options.projectID else {
       fatalError("The Firebase app named \"\(app.name)\" has no project ID in its configuration.")
     }
@@ -269,6 +284,6 @@ public final class FirebaseAI: Sendable {
     let appName: String
     let location: String?
     let apiConfig: APIConfig
-    let aiConfig: FirebaseAIConfig
+    let aiConfig: FirebaseAI.Config
   }
 }

From 086e673479c42ded07a895b1e0b4cccaf4fa254d Mon Sep 17 00:00:00 2001
From: Daymon <daymxn@google.com>
Date: Fri, 11 Jul 2025 12:04:09 -0500
Subject: [PATCH 04/29] Mix invalid references

---
 FirebaseAI/Sources/GenerativeAIService.swift             | 4 ++--
 FirebaseAI/Sources/Types/Public/Imagen/ImagenModel.swift | 2 +-
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/FirebaseAI/Sources/GenerativeAIService.swift b/FirebaseAI/Sources/GenerativeAIService.swift
index f63f2869d4e..beb0fcda3c3 100644
--- a/FirebaseAI/Sources/GenerativeAIService.swift
+++ b/FirebaseAI/Sources/GenerativeAIService.swift
@@ -30,9 +30,9 @@ struct GenerativeAIService {
 
   private let urlSession: URLSession
 
-  private let aiConfig: FirebaseAIConfig
+  private let aiConfig: FirebaseAI.Config
 
-  init(firebaseInfo: FirebaseInfo, urlSession: URLSession, aiConfig: FirebaseAIConfig) {
+  init(firebaseInfo: FirebaseInfo, urlSession: URLSession, aiConfig: FirebaseAI.Config) {
     self.firebaseInfo = firebaseInfo
     self.urlSession = urlSession
     self.aiConfig = aiConfig
diff --git a/FirebaseAI/Sources/Types/Public/Imagen/ImagenModel.swift b/FirebaseAI/Sources/Types/Public/Imagen/ImagenModel.swift
index dca91acb3f9..254e1fe21ea 100644
--- a/FirebaseAI/Sources/Types/Public/Imagen/ImagenModel.swift
+++ b/FirebaseAI/Sources/Types/Public/Imagen/ImagenModel.swift
@@ -53,7 +53,7 @@ public final class ImagenModel {
        generationConfig: ImagenGenerationConfig?,
        safetySettings: ImagenSafetySettings?,
        requestOptions: RequestOptions,
-       urlSession: URLSession = GenAIURLSession.default, aiConfig: FirebaseAIConfig) {
+       urlSession: URLSession = GenAIURLSession.default, aiConfig: FirebaseAI.Config) {
     self.modelResourceName = modelResourceName
     self.apiConfig = apiConfig
     generativeAIService = GenerativeAIService(

From 4c9d28b47c9de8c84a0528f5919a066581565c27 Mon Sep 17 00:00:00 2001
From: Daymon <daymxn@google.com>
Date: Fri, 11 Jul 2025 12:04:38 -0500
Subject: [PATCH 05/29] Fix invalid reference (again)

---
 FirebaseAI/Sources/GenerativeModel.swift | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/FirebaseAI/Sources/GenerativeModel.swift b/FirebaseAI/Sources/GenerativeModel.swift
index 8caa33bcaf7..0a229d3489c 100644
--- a/FirebaseAI/Sources/GenerativeModel.swift
+++ b/FirebaseAI/Sources/GenerativeModel.swift
@@ -87,7 +87,7 @@ public final class GenerativeModel: Sendable {
        toolConfig: ToolConfig? = nil,
        systemInstruction: ModelContent? = nil,
        requestOptions: RequestOptions,
-       urlSession: URLSession = GenAIURLSession.default, aiConfig: FirebaseAIConfig) {
+       urlSession: URLSession = GenAIURLSession.default, aiConfig: FirebaseAI.Config) {
     self.modelName = modelName
     self.modelResourceName = modelResourceName
     self.apiConfig = apiConfig

From 8a06ee5d9a834bc44914c49ca43ca3cfedeebeba Mon Sep 17 00:00:00 2001
From: Daymon <daymxn@google.com>
Date: Fri, 11 Jul 2025 12:06:51 -0500
Subject: [PATCH 06/29] fmt

---
 FirebaseAI/Sources/FirebaseAI.swift | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/FirebaseAI/Sources/FirebaseAI.swift b/FirebaseAI/Sources/FirebaseAI.swift
index 18b2653598e..b9938ced25b 100644
--- a/FirebaseAI/Sources/FirebaseAI.swift
+++ b/FirebaseAI/Sources/FirebaseAI.swift
@@ -38,7 +38,8 @@ public final class FirebaseAI: Sendable {
   /// - Returns: A `FirebaseAI` instance, configured with the custom `FirebaseApp`.
   public static func firebaseAI(app: FirebaseApp? = nil,
                                 backend: Backend = .googleAI(),
-                                config: FirebaseAI.Config = .config(appCheck: AppCheckOptions())) -> FirebaseAI {
+                                config: FirebaseAI
+                                  .Config = .config(appCheck: AppCheckOptions())) -> FirebaseAI {
     let instance = createInstance(
       app: app,
       location: backend.location,
@@ -140,13 +141,13 @@ public final class FirebaseAI: Sendable {
   /// Class to enable FirebaseAI to register via the Objective-C based Firebase component system
   /// to include FirebaseAI in the userAgent.
   @objc(FIRVertexAIComponent) class FirebaseVertexAIComponent: NSObject {}
-  
+
   /// Configuration options for ``FirebaseAI``, which persists across all models.
   @available(iOS 15.0, macOS 12.0, macCatalyst 15.0, tvOS 15.0, watchOS 8.0, *)
-  public struct Config : Sendable, Hashable, Encodable {
+  public struct Config: Sendable, Hashable, Encodable {
     /// Options for App Check specific behavior within a ``FirebaseAI`` instance.
     let appCheck: AppCheckOptions
-    
+
     /// Creates a new ``FirebaseAI.Config`` value.
     ///
     /// - Parameters:
@@ -155,7 +156,7 @@ public final class FirebaseAI: Sendable {
       Config(appCheck: appCheck)
     }
   }
-  
+
   // MARK: - Private
 
   /// Firebase data relevant to Firebase AI.

From 865945590b87bf1fb2c72eeb08cedfbe7eb00e08 Mon Sep 17 00:00:00 2001
From: Daymon <daymxn@google.com>
Date: Tue, 15 Jul 2025 12:36:42 -0500
Subject: [PATCH 07/29] Remove unnecessary Encodable

---
 FirebaseAI/Sources/AppCheckOptions.swift | 2 +-
 FirebaseAI/Sources/FirebaseAI.swift      | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/FirebaseAI/Sources/AppCheckOptions.swift b/FirebaseAI/Sources/AppCheckOptions.swift
index 6411eb39e12..9244c24df62 100644
--- a/FirebaseAI/Sources/AppCheckOptions.swift
+++ b/FirebaseAI/Sources/AppCheckOptions.swift
@@ -16,7 +16,7 @@
 ///
 /// Can be set when creating a ``FirebaseAI.Config``.
 @available(iOS 15.0, macOS 12.0, macCatalyst 15.0, tvOS 15.0, watchOS 8.0, *)
-public struct AppCheckOptions: Sendable, Hashable, Encodable {
+public struct AppCheckOptions: Sendable, Hashable {
   /// Use `limitedUseTokens`, instead of the standard cached tokens, when sending requests
   /// to the backend.
   let requireLimitedUseTokens: Bool
diff --git a/FirebaseAI/Sources/FirebaseAI.swift b/FirebaseAI/Sources/FirebaseAI.swift
index b9938ced25b..a791232a743 100644
--- a/FirebaseAI/Sources/FirebaseAI.swift
+++ b/FirebaseAI/Sources/FirebaseAI.swift
@@ -144,7 +144,7 @@ public final class FirebaseAI: Sendable {
 
   /// Configuration options for ``FirebaseAI``, which persists across all models.
   @available(iOS 15.0, macOS 12.0, macCatalyst 15.0, tvOS 15.0, watchOS 8.0, *)
-  public struct Config: Sendable, Hashable, Encodable {
+  public struct Config: Sendable, Hashable {
     /// Options for App Check specific behavior within a ``FirebaseAI`` instance.
     let appCheck: AppCheckOptions
 

From 56d1f5f4cf2cb0b78a732ad466a03af10a1f0a51 Mon Sep 17 00:00:00 2001
From: Daymon <17409137+daymxn@users.noreply.github.com>
Date: Wed, 16 Jul 2025 15:33:21 -0500
Subject: [PATCH 08/29] Update AppCheckOptions.swift

Co-authored-by: Nick Cooke <36927374+ncooke3@users.noreply.github.com>
---
 FirebaseAI/Sources/AppCheckOptions.swift | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/FirebaseAI/Sources/AppCheckOptions.swift b/FirebaseAI/Sources/AppCheckOptions.swift
index 9244c24df62..a61842ead65 100644
--- a/FirebaseAI/Sources/AppCheckOptions.swift
+++ b/FirebaseAI/Sources/AppCheckOptions.swift
@@ -16,7 +16,7 @@
 ///
 /// Can be set when creating a ``FirebaseAI.Config``.
 @available(iOS 15.0, macOS 12.0, macCatalyst 15.0, tvOS 15.0, watchOS 8.0, *)
-public struct AppCheckOptions: Sendable, Hashable {
+public struct AppCheckOptions: Sendable, Hashable, Equatable {
   /// Use `limitedUseTokens`, instead of the standard cached tokens, when sending requests
   /// to the backend.
   let requireLimitedUseTokens: Bool

From 1b6c09c6789e11d5f76ee9de4b3ed6be356bfbb5 Mon Sep 17 00:00:00 2001
From: Daymon <17409137+daymxn@users.noreply.github.com>
Date: Wed, 16 Jul 2025 15:33:28 -0500
Subject: [PATCH 09/29] Update FirebaseAI.swift

Co-authored-by: Nick Cooke <36927374+ncooke3@users.noreply.github.com>
---
 FirebaseAI/Sources/FirebaseAI.swift | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/FirebaseAI/Sources/FirebaseAI.swift b/FirebaseAI/Sources/FirebaseAI.swift
index a791232a743..720de7cf1e6 100644
--- a/FirebaseAI/Sources/FirebaseAI.swift
+++ b/FirebaseAI/Sources/FirebaseAI.swift
@@ -144,7 +144,7 @@ public final class FirebaseAI: Sendable {
 
   /// Configuration options for ``FirebaseAI``, which persists across all models.
   @available(iOS 15.0, macOS 12.0, macCatalyst 15.0, tvOS 15.0, watchOS 8.0, *)
-  public struct Config: Sendable, Hashable {
+  public struct Config: Sendable, Hashable, Equatable {
     /// Options for App Check specific behavior within a ``FirebaseAI`` instance.
     let appCheck: AppCheckOptions
 

From 1dfbce5cf176f53f4effea2b9fa4d53943a6ced6 Mon Sep 17 00:00:00 2001
From: Daymon <17409137+daymxn@users.noreply.github.com>
Date: Wed, 13 Aug 2025 10:57:41 -0500
Subject: [PATCH 10/29] Update FirebaseAI/Sources/AppCheckOptions.swift

Co-authored-by: Nick Cooke <36927374+ncooke3@users.noreply.github.com>
---
 FirebaseAI/Sources/AppCheckOptions.swift | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/FirebaseAI/Sources/AppCheckOptions.swift b/FirebaseAI/Sources/AppCheckOptions.swift
index a61842ead65..6cb21e4f7f4 100644
--- a/FirebaseAI/Sources/AppCheckOptions.swift
+++ b/FirebaseAI/Sources/AppCheckOptions.swift
@@ -27,7 +27,7 @@ public struct AppCheckOptions: Sendable, Hashable, Equatable {
   ///   - requireLimitedUseTokens: When sending tokens to the backend, this option enables
   ///     the usage of App Check's `limitedUseTokens` instead of the standard cached tokens.
   ///
-  ///     A new `limitedUseToken` will be generated for each request; providing a lower attack
+  ///     A new `limitedUseToken` will be generated for each request; providing a smaller attack
   ///     surface for malicious parties to hijack tokens. When used alongside [replay protection](https://firebase.google.com/docs/app-check/custom-resource-backend#replay-protection),
   ///     `limitedUseTokens` are also _consumed_ after each request, ensuring they can't be used
   ///     again.

From 6dddd094de87067353aa1beefcdbfad60850fa60 Mon Sep 17 00:00:00 2001
From: Daymon <17409137+daymxn@users.noreply.github.com>
Date: Wed, 13 Aug 2025 10:58:14 -0500
Subject: [PATCH 11/29] Update FirebaseAI/Sources/AppCheckOptions.swift

Co-authored-by: Nick Cooke <36927374+ncooke3@users.noreply.github.com>
---
 FirebaseAI/Sources/AppCheckOptions.swift | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/FirebaseAI/Sources/AppCheckOptions.swift b/FirebaseAI/Sources/AppCheckOptions.swift
index 6cb21e4f7f4..e4922bbbd79 100644
--- a/FirebaseAI/Sources/AppCheckOptions.swift
+++ b/FirebaseAI/Sources/AppCheckOptions.swift
@@ -32,7 +32,7 @@ public struct AppCheckOptions: Sendable, Hashable, Equatable {
   ///     `limitedUseTokens` are also _consumed_ after each request, ensuring they can't be used
   ///     again.
   ///
-  ///     _To prevent breakage, this flag is set to `false` by default._
+  ///     _This flag is set to `false` by default._
   ///
   ///     > Important: Replay protection is not currently supported for the FirebaseAI backend.
   ///     > While this feature is being developed, you can still migrate to using

From a188a795c8126e9f7924e969ee7fbe57cf8c6741 Mon Sep 17 00:00:00 2001
From: Daymon <17409137+daymxn@users.noreply.github.com>
Date: Wed, 13 Aug 2025 10:58:21 -0500
Subject: [PATCH 12/29] Update FirebaseAI/Sources/AppCheckOptions.swift

Co-authored-by: Nick Cooke <36927374+ncooke3@users.noreply.github.com>
---
 FirebaseAI/Sources/AppCheckOptions.swift | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/FirebaseAI/Sources/AppCheckOptions.swift b/FirebaseAI/Sources/AppCheckOptions.swift
index e4922bbbd79..27ac1546b32 100644
--- a/FirebaseAI/Sources/AppCheckOptions.swift
+++ b/FirebaseAI/Sources/AppCheckOptions.swift
@@ -36,7 +36,7 @@ public struct AppCheckOptions: Sendable, Hashable, Equatable {
   ///
   ///     > Important: Replay protection is not currently supported for the FirebaseAI backend.
   ///     > While this feature is being developed, you can still migrate to using
-  ///     > `limitedUseTokens`. Because `limitedUseTokens` are backwards compatable, you can still
+  ///     > `limitedUseTokens`. Because `limitedUseTokens` are backwards compatible, you can still
   ///     > use them without replay protection. Due to their shorter TTL over standard App Check
   ///     > tokens, they still provide a security benefit.
   ///     >

From fa2bc361ff71df0ab6865dbf1b300e3c21b23eda Mon Sep 17 00:00:00 2001
From: Daymon <daymxn@google.com>
Date: Wed, 13 Aug 2025 11:10:55 -0500
Subject: [PATCH 13/29] Add changelog entry

---
 FirebaseAI/CHANGELOG.md | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/FirebaseAI/CHANGELOG.md b/FirebaseAI/CHANGELOG.md
index 47b2627da67..53697bbf001 100644
--- a/FirebaseAI/CHANGELOG.md
+++ b/FirebaseAI/CHANGELOG.md
@@ -1,3 +1,11 @@
+# Unreleased
+- [feature] Added support for using App Check's `limitedUseTokens` feature when generating tokens.
+This must be explicitly enabled via the new `FirebaseAI.Config` struct, when initializing an
+instance of `FirebaseAI`. While [replay protection](https://firebase.google.com/docs/app-check/custom-resource-backend#replay-protection)
+is not currently supported for the Firebase AI Logic SDK, we plan to roll it out in the future. As
+such, consumers should migrate to using `limitedUseTokens` _now_, so that when replay protection
+support is added, consumers can enable it without breaking their app for users.
+
 # 12.0.0
 - [added] Added support for Grounding with Google Search. (#15014)
 - [removed] Removed `CountTokensResponse.totalBillableCharacters` which was

From 8ab664c99b9a4b49145cac263dd9e769c1bed280 Mon Sep 17 00:00:00 2001
From: Daymon <daymxn@google.com>
Date: Wed, 13 Aug 2025 11:18:01 -0500
Subject: [PATCH 14/29] Update tests using `createInstance`

---
 FirebaseAI/Tests/Unit/VertexComponentTests.swift | 15 +++++++++------
 1 file changed, 9 insertions(+), 6 deletions(-)

diff --git a/FirebaseAI/Tests/Unit/VertexComponentTests.swift b/FirebaseAI/Tests/Unit/VertexComponentTests.swift
index 7202e01f4d6..31fff4b8d02 100644
--- a/FirebaseAI/Tests/Unit/VertexComponentTests.swift
+++ b/FirebaseAI/Tests/Unit/VertexComponentTests.swift
@@ -155,12 +155,14 @@ class VertexComponentTests: XCTestCase {
     let vertex1 = FirebaseAI.createInstance(
       app: VertexComponentTests.app,
       location: location,
-      apiConfig: APIConfig(service: .vertexAI(endpoint: .firebaseProxyProd), version: .v1beta)
+      apiConfig: APIConfig(service: .vertexAI(endpoint: .firebaseProxyProd), version: .v1beta),
+      aiConfig: .config()
     )
     let vertex2 = FirebaseAI.createInstance(
       app: VertexComponentTests.app,
       location: location,
-      apiConfig: APIConfig(service: .vertexAI(endpoint: .firebaseProxyProd), version: .v1)
+      apiConfig: APIConfig(service: .vertexAI(endpoint: .firebaseProxyProd), version: .v1),
+      aiConfig: .config()
     )
 
     // Ensure they are different instances.
@@ -181,7 +183,8 @@ class VertexComponentTests: XCTestCase {
       let vertex = FirebaseAI(
         app: app1,
         location: "transitory location",
-        apiConfig: FirebaseAI.defaultVertexAIAPIConfig
+        apiConfig: FirebaseAI.defaultVertexAIAPIConfig,
+        aiConfig: .config()
       )
       weakVertex = vertex
       XCTAssertNotNil(weakVertex)
@@ -208,7 +211,7 @@ class VertexComponentTests: XCTestCase {
   func testModelResourceName_developerAPI_generativeLanguage() throws {
     let app = try XCTUnwrap(VertexComponentTests.app)
     let apiConfig = APIConfig(service: .googleAI(endpoint: .googleAIBypassProxy), version: .v1beta)
-    let vertex = FirebaseAI.createInstance(app: app, location: nil, apiConfig: apiConfig)
+    let vertex = FirebaseAI.createInstance(app: app, location: nil, apiConfig: apiConfig, aiConfig: .config())
     let model = "test-model-name"
 
     let modelResourceName = vertex.modelResourceName(modelName: model)
@@ -222,7 +225,7 @@ class VertexComponentTests: XCTestCase {
       service: .googleAI(endpoint: .firebaseProxyStaging),
       version: .v1beta
     )
-    let vertex = FirebaseAI.createInstance(app: app, location: nil, apiConfig: apiConfig)
+    let vertex = FirebaseAI.createInstance(app: app, location: nil, apiConfig: apiConfig, aiConfig: .config())
     let model = "test-model-name"
     let projectID = vertex.firebaseInfo.projectID
 
@@ -253,7 +256,7 @@ class VertexComponentTests: XCTestCase {
       service: .googleAI(endpoint: .firebaseProxyStaging),
       version: .v1beta
     )
-    let vertex = FirebaseAI.createInstance(app: app, location: nil, apiConfig: apiConfig)
+    let vertex = FirebaseAI.createInstance(app: app, location: nil, apiConfig: apiConfig, aiConfig: .config())
     let modelResourceName = vertex.modelResourceName(modelName: modelName)
     let expectedSystemInstruction = ModelContent(role: nil, parts: systemInstruction.parts)
 

From 860ee49b41b880819266700bd25b2d559c41a4f9 Mon Sep 17 00:00:00 2001
From: Daymon <daymxn@google.com>
Date: Wed, 13 Aug 2025 11:18:18 -0500
Subject: [PATCH 15/29] Use default params when initializing config

---
 FirebaseAI/Sources/FirebaseAI.swift | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/FirebaseAI/Sources/FirebaseAI.swift b/FirebaseAI/Sources/FirebaseAI.swift
index 720de7cf1e6..d32de317c33 100644
--- a/FirebaseAI/Sources/FirebaseAI.swift
+++ b/FirebaseAI/Sources/FirebaseAI.swift
@@ -38,8 +38,7 @@ public final class FirebaseAI: Sendable {
   /// - Returns: A `FirebaseAI` instance, configured with the custom `FirebaseApp`.
   public static func firebaseAI(app: FirebaseApp? = nil,
                                 backend: Backend = .googleAI(),
-                                config: FirebaseAI
-                                  .Config = .config(appCheck: AppCheckOptions())) -> FirebaseAI {
+                                config: FirebaseAI.Config = .config()) -> FirebaseAI {
     let instance = createInstance(
       app: app,
       location: backend.location,

From 187de4f34936b5013e9a03e90109c637cf35e6ba Mon Sep 17 00:00:00 2001
From: Daymon <daymxn@google.com>
Date: Wed, 13 Aug 2025 11:20:02 -0500
Subject: [PATCH 16/29] formatting

---
 .../Tests/Unit/VertexComponentTests.swift     | 21 ++++++++++++++++---
 1 file changed, 18 insertions(+), 3 deletions(-)

diff --git a/FirebaseAI/Tests/Unit/VertexComponentTests.swift b/FirebaseAI/Tests/Unit/VertexComponentTests.swift
index 31fff4b8d02..4d7309ca697 100644
--- a/FirebaseAI/Tests/Unit/VertexComponentTests.swift
+++ b/FirebaseAI/Tests/Unit/VertexComponentTests.swift
@@ -211,7 +211,12 @@ class VertexComponentTests: XCTestCase {
   func testModelResourceName_developerAPI_generativeLanguage() throws {
     let app = try XCTUnwrap(VertexComponentTests.app)
     let apiConfig = APIConfig(service: .googleAI(endpoint: .googleAIBypassProxy), version: .v1beta)
-    let vertex = FirebaseAI.createInstance(app: app, location: nil, apiConfig: apiConfig, aiConfig: .config())
+    let vertex = FirebaseAI.createInstance(
+      app: app,
+      location: nil,
+      apiConfig: apiConfig,
+      aiConfig: .config()
+    )
     let model = "test-model-name"
 
     let modelResourceName = vertex.modelResourceName(modelName: model)
@@ -225,7 +230,12 @@ class VertexComponentTests: XCTestCase {
       service: .googleAI(endpoint: .firebaseProxyStaging),
       version: .v1beta
     )
-    let vertex = FirebaseAI.createInstance(app: app, location: nil, apiConfig: apiConfig, aiConfig: .config())
+    let vertex = FirebaseAI.createInstance(
+      app: app,
+      location: nil,
+      apiConfig: apiConfig,
+      aiConfig: .config()
+    )
     let model = "test-model-name"
     let projectID = vertex.firebaseInfo.projectID
 
@@ -256,7 +266,12 @@ class VertexComponentTests: XCTestCase {
       service: .googleAI(endpoint: .firebaseProxyStaging),
       version: .v1beta
     )
-    let vertex = FirebaseAI.createInstance(app: app, location: nil, apiConfig: apiConfig, aiConfig: .config())
+    let vertex = FirebaseAI.createInstance(
+      app: app,
+      location: nil,
+      apiConfig: apiConfig,
+      aiConfig: .config()
+    )
     let modelResourceName = vertex.modelResourceName(modelName: modelName)
     let expectedSystemInstruction = ModelContent(role: nil, parts: systemInstruction.parts)
 

From 10f445cead2e5303103e464180b24bafb1b8b6b3 Mon Sep 17 00:00:00 2001
From: Daymon <daymxn@google.com>
Date: Wed, 13 Aug 2025 11:20:46 -0500
Subject: [PATCH 17/29] manual formatting

---
 FirebaseAI/Sources/GenerativeModel.swift | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/FirebaseAI/Sources/GenerativeModel.swift b/FirebaseAI/Sources/GenerativeModel.swift
index 0a229d3489c..d3c3bddeebf 100644
--- a/FirebaseAI/Sources/GenerativeModel.swift
+++ b/FirebaseAI/Sources/GenerativeModel.swift
@@ -87,7 +87,8 @@ public final class GenerativeModel: Sendable {
        toolConfig: ToolConfig? = nil,
        systemInstruction: ModelContent? = nil,
        requestOptions: RequestOptions,
-       urlSession: URLSession = GenAIURLSession.default, aiConfig: FirebaseAI.Config) {
+       urlSession: URLSession = GenAIURLSession.default,
+       aiConfig: FirebaseAI.Config) {
     self.modelName = modelName
     self.modelResourceName = modelResourceName
     self.apiConfig = apiConfig

From 8ce15d28b2b787a363029280cb28e38a6aff5e4b Mon Sep 17 00:00:00 2001
From: Daymon <daymxn@google.com>
Date: Wed, 13 Aug 2025 11:29:14 -0500
Subject: [PATCH 18/29] Fix broken link in unit tests

---
 FirebaseAI/Tests/Unit/README.md | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/FirebaseAI/Tests/Unit/README.md b/FirebaseAI/Tests/Unit/README.md
index 9463d595294..88019041f9f 100644
--- a/FirebaseAI/Tests/Unit/README.md
+++ b/FirebaseAI/Tests/Unit/README.md
@@ -1,3 +1,3 @@
 See the Firebase AI SDK
-[README](https://github.com/firebase/firebase-ios-sdk/tree/main/FirebaseVertexAI#unit-tests)
+[README](https://github.com/firebase/firebase-ios-sdk/tree/main/FirebaseAI#unit-tests)
 for required setup instructions.

From ce0da477adb9ce1324ebdcde995101796bc91651 Mon Sep 17 00:00:00 2001
From: Daymon <daymxn@google.com>
Date: Wed, 13 Aug 2025 11:34:15 -0500
Subject: [PATCH 19/29] Add missing default arg on GenerativeModel for config

---
 FirebaseAI/Sources/GenerativeModel.swift | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/FirebaseAI/Sources/GenerativeModel.swift b/FirebaseAI/Sources/GenerativeModel.swift
index d3c3bddeebf..28dfa4e7eed 100644
--- a/FirebaseAI/Sources/GenerativeModel.swift
+++ b/FirebaseAI/Sources/GenerativeModel.swift
@@ -88,7 +88,7 @@ public final class GenerativeModel: Sendable {
        systemInstruction: ModelContent? = nil,
        requestOptions: RequestOptions,
        urlSession: URLSession = GenAIURLSession.default,
-       aiConfig: FirebaseAI.Config) {
+       aiConfig: FirebaseAI.Config = .config()) {
     self.modelName = modelName
     self.modelResourceName = modelResourceName
     self.apiConfig = apiConfig

From 9a9a1c5b1e363d8af344ef3e38dc53f4d344b1c5 Mon Sep 17 00:00:00 2001
From: Daymon <17409137+daymxn@users.noreply.github.com>
Date: Wed, 13 Aug 2025 13:52:02 -0500
Subject: [PATCH 20/29] Update FirebaseAI/CHANGELOG.md

Co-authored-by: Nick Cooke <36927374+ncooke3@users.noreply.github.com>
---
 FirebaseAI/CHANGELOG.md | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/FirebaseAI/CHANGELOG.md b/FirebaseAI/CHANGELOG.md
index 53697bbf001..3bcf708d016 100644
--- a/FirebaseAI/CHANGELOG.md
+++ b/FirebaseAI/CHANGELOG.md
@@ -1,10 +1,11 @@
 # Unreleased
-- [feature] Added support for using App Check's `limitedUseTokens` feature when generating tokens.
-This must be explicitly enabled via the new `FirebaseAI.Config` struct, when initializing an
-instance of `FirebaseAI`. While [replay protection](https://firebase.google.com/docs/app-check/custom-resource-backend#replay-protection)
-is not currently supported for the Firebase AI Logic SDK, we plan to roll it out in the future. As
-such, consumers should migrate to using `limitedUseTokens` _now_, so that when replay protection
-support is added, consumers can enable it without breaking their app for users.
+- [feature] Added a new configuration option to require limited-use App
+  Check tokens for attesting Firebase AI Logic requests. This enhances
+  security against replay attacks. To use this feature, configure it
+  explicitly via the new `FirebaseAI.Config` struct when initializing
+  `FirebaseAI`. We recommend migrating to limited-use tokens now, so
+  your app will be ready to take advantage of replay protection when
+  it becomes available for Firebase AI Logic.
 
 # 12.0.0
 - [added] Added support for Grounding with Google Search. (#15014)

From 446f62d180cc6631b993f89c79bd1559bdc82683 Mon Sep 17 00:00:00 2001
From: Daymon <daymxn@google.com>
Date: Wed, 13 Aug 2025 14:01:35 -0500
Subject: [PATCH 21/29] Add error message

---
 FirebaseAI/Sources/GenerativeAIService.swift | 28 ++++++++++++--------
 1 file changed, 17 insertions(+), 11 deletions(-)

diff --git a/FirebaseAI/Sources/GenerativeAIService.swift b/FirebaseAI/Sources/GenerativeAIService.swift
index beb0fcda3c3..6e70beeb869 100644
--- a/FirebaseAI/Sources/GenerativeAIService.swift
+++ b/FirebaseAI/Sources/GenerativeAIService.swift
@@ -180,7 +180,7 @@ struct GenerativeAIService {
     urlRequest.setValue("application/json", forHTTPHeaderField: "Content-Type")
 
     if let appCheck = firebaseInfo.appCheck {
-      let tokenResult = await fetchAppCheckToken(appCheck: appCheck)
+      let tokenResult = try await fetchAppCheckToken(appCheck: appCheck)
       urlRequest.setValue(tokenResult.token, forHTTPHeaderField: "X-Firebase-AppCheck")
       if let error = tokenResult.error {
         AILog.error(
@@ -210,18 +210,24 @@ struct GenerativeAIService {
     return urlRequest
   }
 
-  private func fetchAppCheckToken(appCheck: AppCheckInterop) async
+  private func fetchAppCheckToken(appCheck: AppCheckInterop) async throws
     -> FIRAppCheckTokenResultInterop {
-    if aiConfig.appCheck.requireLimitedUseTokens {
-      if let token = await appCheck.getLimitedUseToken?() {
-        return token
-      }
+      if aiConfig.appCheck.requireLimitedUseTokens {
+        if let token = await appCheck.getLimitedUseToken?() {
+          return token
+        }
 
-      AILog.error(
-        code: .appCheckTokenFetchFailed,
-        "Missing getLimitedUseToken() function, but requireLimitedUseTokens was enabled."
-      )
-      // falls back to standard token
+        let errorMessage = "The provided App Check token provider doesn't implement getLimitedUseToken(), but requireLimitedUseTokens was enabled.";
+
+        #if Debug
+          fatalError(errorMessage)
+        #else
+          throw NSError(
+            domain: "com.google.firebase.ai.GenerativeAIService",
+            code: AILog.MessageCode.appCheckTokenFetchFailed.rawValue,
+            userInfo: [NSLocalizedDescriptionKey: errorMessage]
+          )
+        #endif
     }
 
     return await appCheck.getToken(forcingRefresh: false)

From 61c5ad6dd0757cfa85468ec1cf3fd4d32341f7d8 Mon Sep 17 00:00:00 2001
From: Daymon <daymxn@google.com>
Date: Wed, 13 Aug 2025 14:02:39 -0500
Subject: [PATCH 22/29] formatting

---
 FirebaseAI/Sources/GenerativeAIService.swift | 29 ++++++++++----------
 1 file changed, 15 insertions(+), 14 deletions(-)

diff --git a/FirebaseAI/Sources/GenerativeAIService.swift b/FirebaseAI/Sources/GenerativeAIService.swift
index 6e70beeb869..66f12528eff 100644
--- a/FirebaseAI/Sources/GenerativeAIService.swift
+++ b/FirebaseAI/Sources/GenerativeAIService.swift
@@ -212,22 +212,23 @@ struct GenerativeAIService {
 
   private func fetchAppCheckToken(appCheck: AppCheckInterop) async throws
     -> FIRAppCheckTokenResultInterop {
-      if aiConfig.appCheck.requireLimitedUseTokens {
-        if let token = await appCheck.getLimitedUseToken?() {
-          return token
-        }
+    if aiConfig.appCheck.requireLimitedUseTokens {
+      if let token = await appCheck.getLimitedUseToken?() {
+        return token
+      }
 
-        let errorMessage = "The provided App Check token provider doesn't implement getLimitedUseToken(), but requireLimitedUseTokens was enabled.";
+      let errorMessage =
+        "The provided App Check token provider doesn't implement getLimitedUseToken(), but requireLimitedUseTokens was enabled."
 
-        #if Debug
-          fatalError(errorMessage)
-        #else
-          throw NSError(
-            domain: "com.google.firebase.ai.GenerativeAIService",
-            code: AILog.MessageCode.appCheckTokenFetchFailed.rawValue,
-            userInfo: [NSLocalizedDescriptionKey: errorMessage]
-          )
-        #endif
+      #if Debug
+        fatalError(errorMessage)
+      #else
+        throw NSError(
+          domain: "com.google.firebase.ai.GenerativeAIService",
+          code: AILog.MessageCode.appCheckTokenFetchFailed.rawValue,
+          userInfo: [NSLocalizedDescriptionKey: errorMessage]
+        )
+      #endif
     }
 
     return await appCheck.getToken(forcingRefresh: false)

From 9c551c77b25f1a2f6b0245150a4da98b93decfcc Mon Sep 17 00:00:00 2001
From: Daymon <daymxn@google.com>
Date: Wed, 13 Aug 2025 14:07:45 -0500
Subject: [PATCH 23/29] Update domain to be more adaptive

---
 FirebaseAI/Sources/GenerativeAIService.swift | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/FirebaseAI/Sources/GenerativeAIService.swift b/FirebaseAI/Sources/GenerativeAIService.swift
index 66f12528eff..3c76630822d 100644
--- a/FirebaseAI/Sources/GenerativeAIService.swift
+++ b/FirebaseAI/Sources/GenerativeAIService.swift
@@ -224,7 +224,7 @@ struct GenerativeAIService {
         fatalError(errorMessage)
       #else
         throw NSError(
-          domain: "com.google.firebase.ai.GenerativeAIService",
+          domain: "\(Constants.baseErrorDomain).\(Self.self)",
           code: AILog.MessageCode.appCheckTokenFetchFailed.rawValue,
           userInfo: [NSLocalizedDescriptionKey: errorMessage]
         )

From cc578bdf9b079c29fb8e315a5e4298d34e0ca384 Mon Sep 17 00:00:00 2001
From: Daymon <17409137+daymxn@users.noreply.github.com>
Date: Wed, 13 Aug 2025 16:02:42 -0500
Subject: [PATCH 24/29] Update AppCheckOptions.swift

Co-authored-by: Nick Cooke <36927374+ncooke3@users.noreply.github.com>
---
 FirebaseAI/Sources/AppCheckOptions.swift | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/FirebaseAI/Sources/AppCheckOptions.swift b/FirebaseAI/Sources/AppCheckOptions.swift
index 27ac1546b32..4c9d7a981ee 100644
--- a/FirebaseAI/Sources/AppCheckOptions.swift
+++ b/FirebaseAI/Sources/AppCheckOptions.swift
@@ -29,7 +29,7 @@ public struct AppCheckOptions: Sendable, Hashable, Equatable {
   ///
   ///     A new `limitedUseToken` will be generated for each request; providing a smaller attack
   ///     surface for malicious parties to hijack tokens. When used alongside [replay protection](https://firebase.google.com/docs/app-check/custom-resource-backend#replay-protection),
-  ///     `limitedUseTokens` are also _consumed_ after each request, ensuring they can't be used
+  ///     limited-use tokens are also _consumed_ after each request, ensuring they can't be used
   ///     again.
   ///
   ///     _This flag is set to `false` by default._

From 604ec4c091a3d02f47ccf5030f228a45c599ab7d Mon Sep 17 00:00:00 2001
From: Daymon <17409137+daymxn@users.noreply.github.com>
Date: Wed, 13 Aug 2025 16:02:51 -0500
Subject: [PATCH 25/29] Update AppCheckOptions.swift

Co-authored-by: Nick Cooke <36927374+ncooke3@users.noreply.github.com>
---
 FirebaseAI/Sources/AppCheckOptions.swift | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/FirebaseAI/Sources/AppCheckOptions.swift b/FirebaseAI/Sources/AppCheckOptions.swift
index 4c9d7a981ee..c253d776562 100644
--- a/FirebaseAI/Sources/AppCheckOptions.swift
+++ b/FirebaseAI/Sources/AppCheckOptions.swift
@@ -27,7 +27,7 @@ public struct AppCheckOptions: Sendable, Hashable, Equatable {
   ///   - requireLimitedUseTokens: When sending tokens to the backend, this option enables
   ///     the usage of App Check's `limitedUseTokens` instead of the standard cached tokens.
   ///
-  ///     A new `limitedUseToken` will be generated for each request; providing a smaller attack
+  ///     A new limited-use tokens will be generated for each request; providing a smaller attack
   ///     surface for malicious parties to hijack tokens. When used alongside [replay protection](https://firebase.google.com/docs/app-check/custom-resource-backend#replay-protection),
   ///     limited-use tokens are also _consumed_ after each request, ensuring they can't be used
   ///     again.

From 9ef2511fe00cb6dedeb075600c0765f58ba35b59 Mon Sep 17 00:00:00 2001
From: Daymon <17409137+daymxn@users.noreply.github.com>
Date: Wed, 13 Aug 2025 16:03:06 -0500
Subject: [PATCH 26/29] Update AppCheckOptions.swift

Co-authored-by: Nick Cooke <36927374+ncooke3@users.noreply.github.com>
---
 FirebaseAI/Sources/AppCheckOptions.swift | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/FirebaseAI/Sources/AppCheckOptions.swift b/FirebaseAI/Sources/AppCheckOptions.swift
index c253d776562..062b989af5d 100644
--- a/FirebaseAI/Sources/AppCheckOptions.swift
+++ b/FirebaseAI/Sources/AppCheckOptions.swift
@@ -25,7 +25,7 @@ public struct AppCheckOptions: Sendable, Hashable, Equatable {
   ///
   /// - Parameters:
   ///   - requireLimitedUseTokens: When sending tokens to the backend, this option enables
-  ///     the usage of App Check's `limitedUseTokens` instead of the standard cached tokens.
+  ///     the usage of App Check's limited-use tokens instead of the standard cached tokens.
   ///
   ///     A new limited-use tokens will be generated for each request; providing a smaller attack
   ///     surface for malicious parties to hijack tokens. When used alongside [replay protection](https://firebase.google.com/docs/app-check/custom-resource-backend#replay-protection),

From 0857ffaaa92f799d3ff89f7bca8370bc46075fcb Mon Sep 17 00:00:00 2001
From: Daymon <17409137+daymxn@users.noreply.github.com>
Date: Wed, 13 Aug 2025 16:34:02 -0500
Subject: [PATCH 27/29] Update AppCheckOptions.swift

Co-authored-by: Nick Cooke <36927374+ncooke3@users.noreply.github.com>
---
 FirebaseAI/Sources/AppCheckOptions.swift | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/FirebaseAI/Sources/AppCheckOptions.swift b/FirebaseAI/Sources/AppCheckOptions.swift
index 062b989af5d..990f644e1de 100644
--- a/FirebaseAI/Sources/AppCheckOptions.swift
+++ b/FirebaseAI/Sources/AppCheckOptions.swift
@@ -28,7 +28,7 @@ public struct AppCheckOptions: Sendable, Hashable, Equatable {
   ///     the usage of App Check's limited-use tokens instead of the standard cached tokens.
   ///
   ///     A new limited-use tokens will be generated for each request; providing a smaller attack
-  ///     surface for malicious parties to hijack tokens. When used alongside [replay protection](https://firebase.google.com/docs/app-check/custom-resource-backend#replay-protection),
+  ///     surface for malicious parties to hijack tokens. When used alongside replay protection,
   ///     limited-use tokens are also _consumed_ after each request, ensuring they can't be used
   ///     again.
   ///

From d3e31eb9656f3381af54e722c7b446896b6140eb Mon Sep 17 00:00:00 2001
From: Daymon <17409137+daymxn@users.noreply.github.com>
Date: Wed, 13 Aug 2025 16:34:09 -0500
Subject: [PATCH 28/29] Update AppCheckOptions.swift

Co-authored-by: Nick Cooke <36927374+ncooke3@users.noreply.github.com>
---
 FirebaseAI/Sources/AppCheckOptions.swift | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/FirebaseAI/Sources/AppCheckOptions.swift b/FirebaseAI/Sources/AppCheckOptions.swift
index 990f644e1de..235f689e4de 100644
--- a/FirebaseAI/Sources/AppCheckOptions.swift
+++ b/FirebaseAI/Sources/AppCheckOptions.swift
@@ -36,11 +36,11 @@ public struct AppCheckOptions: Sendable, Hashable, Equatable {
   ///
   ///     > Important: Replay protection is not currently supported for the FirebaseAI backend.
   ///     > While this feature is being developed, you can still migrate to using
-  ///     > `limitedUseTokens`. Because `limitedUseTokens` are backwards compatible, you can still
+  ///     > limited-use tokens. Because limited-use tokens are backwards compatible, you can still
   ///     > use them without replay protection. Due to their shorter TTL over standard App Check
   ///     > tokens, they still provide a security benefit.
   ///     >
-  ///     > Migrating to `limitedUseTokens` ahead of time will also allow you to enable replay
+  ///     > Migrating to limited-use tokens ahead of time will also allow you to enable replay
   ///     > protection down the road (when support is added), without breaking your users.
   public init(requireLimitedUseTokens: Bool = false) {
     self.requireLimitedUseTokens = requireLimitedUseTokens

From df24a840cc4564b3d0333aa38ed856f97333b217 Mon Sep 17 00:00:00 2001
From: Daymon <17409137+daymxn@users.noreply.github.com>
Date: Wed, 13 Aug 2025 16:58:38 -0500
Subject: [PATCH 29/29] Update FirebaseAI/Sources/AppCheckOptions.swift

Co-authored-by: Nick Cooke <36927374+ncooke3@users.noreply.github.com>
---
 FirebaseAI/Sources/AppCheckOptions.swift | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/FirebaseAI/Sources/AppCheckOptions.swift b/FirebaseAI/Sources/AppCheckOptions.swift
index 235f689e4de..c3eec18c0e8 100644
--- a/FirebaseAI/Sources/AppCheckOptions.swift
+++ b/FirebaseAI/Sources/AppCheckOptions.swift
@@ -40,8 +40,8 @@ public struct AppCheckOptions: Sendable, Hashable, Equatable {
   ///     > use them without replay protection. Due to their shorter TTL over standard App Check
   ///     > tokens, they still provide a security benefit.
   ///     >
-  ///     > Migrating to limited-use tokens ahead of time will also allow you to enable replay
-  ///     > protection down the road (when support is added), without breaking your users.
+  ///   > Migrating to limited-use tokens sooner minimizes disruption when support for replay
+  ///   > protection is added.
   public init(requireLimitedUseTokens: Bool = false) {
     self.requireLimitedUseTokens = requireLimitedUseTokens
   }