[FirebaseAI] Add AgentPlatform backend

firebaseai/src/Citation.cs

@@ -55,6 +55,7 @@ internal static CitationMetadata FromJson(Dictionary<string, object> jsonDict,
       {
         FirebaseAI.Backend.InternalProvider.GoogleAI => "citationSources",
         FirebaseAI.Backend.InternalProvider.VertexAI => "citations",
+        FirebaseAI.Backend.InternalProvider.AgentPlatform => "citations",
         _ => throw new ArgumentOutOfRangeException(nameof(backend), backend,
                            "Unsupported or unhandled backend provider encountered.")
       };

firebaseai/src/FirebaseAI.cs

@@ -37,7 +37,8 @@ public readonly struct Backend
       internal enum InternalProvider
       {
         GoogleAI,
-        VertexAI
+        VertexAI,
+        AgentPlatform,
       }
 
       /// <summary>
@@ -47,7 +48,7 @@ internal enum InternalProvider
       internal InternalProvider Provider { get; }
       /// <summary>
       /// Intended for internal use only.
-      /// The region identifier used by the Vertex AI backend.
+      /// The region identifier used by the Vertex AI and Agent Platform backends.
       /// </summary>
       internal string Location { get; }
 
@@ -68,9 +69,9 @@ public static Backend GoogleAI()
       /// <summary>
       /// The Vertex AI backend service configuration.
       /// </summary>
-      /// <param name="location">The region identifier, defaulting to `us-central1`; see [Vertex AI
-      ///     regions](https://cloud.google.com/vertex-ai/generative-ai/docs/learn/locations#available-regions)
-      ///     for a list of supported regions.</param>
+      /// <param name="location">The region identifier, defaulting to `us-central1`</param>
+      /// @deprecated Use AgentPlatform instead. Note that the default location changes to 'global'
+      [Obsolete("Use AgentPlatform instead. Note that the default location changes to 'global'")]
       public static Backend VertexAI(string location = "us-central1")
       {
         if (string.IsNullOrWhiteSpace(location) || location.Contains("/"))
@@ -82,6 +83,21 @@ public static Backend VertexAI(string location = "us-central1")
         return new Backend(InternalProvider.VertexAI, location);
       }
 
+      /// <summary>
+      /// The Agent Platform backend service configuration.
+      /// </summary>
+      /// <param name="location">The region identifier, defaulting to `global`</param>
+      public static Backend AgentPlatform(string location = "global")
+      {
+        if (string.IsNullOrWhiteSpace(location) || location.Contains("/"))
+        {
+          throw new ArgumentException(
+              $"The location argument must be non-empty, and not contain special characters like '/'");
+        }
+
+        return new Backend(InternalProvider.AgentPlatform, location);
+      }
+
       public override readonly string ToString()
       {
         return $"FirebaseAIBackend|{Provider}|{Location}";

firebaseai/src/GenerativeModel.cs

@@ -421,6 +421,7 @@ private string MakeCountTokensRequest(IEnumerable<ModelContent> contents)
               $"models/{_modelName}";
           break;
         case FirebaseAI.Backend.InternalProvider.VertexAI:
+        case FirebaseAI.Backend.InternalProvider.AgentPlatform:
           jsonDict = new()
           {
             // Convert the Contents into a list of Json dictionaries

firebaseai/src/Internal/HttpHelpers.cs

@@ -30,7 +30,8 @@ internal static class HttpHelpers
     internal static string GetURL(FirebaseApp firebaseApp,
         FirebaseAI.Backend backend, string modelName)
     {
-      if (backend.Provider == FirebaseAI.Backend.InternalProvider.VertexAI)
+      if (backend.Provider == FirebaseAI.Backend.InternalProvider.VertexAI ||
+          backend.Provider == FirebaseAI.Backend.InternalProvider.AgentPlatform)
       {
         return "https://firebasevertexai.googleapis.com/v1beta" +
             "/projects/" + firebaseApp.Options.ProjectId +
@@ -54,7 +55,8 @@ internal static string GetTemplateURL(FirebaseApp firebaseApp,
     {
       var projectUrl = "https://firebasevertexai.googleapis.com/v1beta" +
           $"/projects/{firebaseApp.Options.ProjectId}";
-      if (backend.Provider == FirebaseAI.Backend.InternalProvider.VertexAI)
+      if (backend.Provider == FirebaseAI.Backend.InternalProvider.VertexAI ||
+          backend.Provider == FirebaseAI.Backend.InternalProvider.AgentPlatform)
       {
         return $"{projectUrl}/locations/{backend.Location}/templates/{templateId}";
       }

firebaseai/src/LiveGenerativeModel.cs

@@ -76,7 +76,8 @@ internal LiveGenerativeModel(FirebaseApp firebaseApp,
 
     private string GetURL()
     {
-      if (_backend.Provider == FirebaseAI.Backend.InternalProvider.VertexAI)
+      if (_backend.Provider == FirebaseAI.Backend.InternalProvider.VertexAI ||
+          _backend.Provider == FirebaseAI.Backend.InternalProvider.AgentPlatform)
       {
         return "wss://firebasevertexai.googleapis.com/ws" +
                "/google.firebase.vertexai.v1beta.LlmBidiService/BidiGenerateContent" +
@@ -97,7 +98,8 @@ private string GetURL()
 
     private string GetModelName()
     {
-      if (_backend.Provider == FirebaseAI.Backend.InternalProvider.VertexAI)
+      if (_backend.Provider == FirebaseAI.Backend.InternalProvider.VertexAI ||
+          _backend.Provider == FirebaseAI.Backend.InternalProvider.AgentPlatform)
       {
         return $"projects/{_firebaseApp.Options.ProjectId}/locations/{_backend.Location}" +
                $"/publishers/google/models/{_modelName}";

firebaseai/testapp/Assets/Firebase/Sample/FirebaseAI/UIHandler.cs

@@ -44,7 +44,7 @@ public class UIHandler : MonoBehaviour {
 
     private string appCheckDebugToken = "REPLACE_WITH_APP_CHECK_TOKEN";
 
-    protected void InitializeAppCheck() {
+    protected virtual void InitializeAppCheck() {
       DebugLog("Initializing App Check directly in manual UIHandler");
       DebugAppCheckProviderFactory.Instance.SetDebugToken(appCheckDebugToken);
       FirebaseAppCheck.SetAppCheckProviderFactory(DebugAppCheckProviderFactory.Instance);
@@ -76,11 +76,11 @@ protected void InitializeFirebase() {
     public string ModelName = "gemini-3.1-flash-lite";
 
     private int backendSelection = 0;
-    private string[] backendChoices = new string[] { "Google AI Backend", "Vertex AI Backend" };
+    private string[] backendChoices = new string[] { "Google AI Backend", "Agent Platform Backend" };
     private GenerativeModel GetModel() {
       var backend = backendSelection == 0
           ? FirebaseAI.Backend.GoogleAI()
-          : FirebaseAI.Backend.VertexAI();
+          : FirebaseAI.Backend.AgentPlatform();
 
       return FirebaseAI.GetInstance(backend, useLimitedUseAppCheckTokens: true).GetGenerativeModel(ModelName);
     }