[AI] ImageConfig and FinishReasons

firebaseai/src/Candidate.cs

@@ -64,6 +64,46 @@ public enum FinishReason
     /// Token generation was stopped because the function call generated by the model was invalid.
     /// </summary>
     MalformedFunctionCall,
+    /// <summary>
+    /// Token generation stopped because generated images contain safety violations.
+    /// </summary>
+    ImageSafety,
+    /// <summary>
+    /// Image generation stopped because generated images have other prohibited content.
+    /// </summary>
+    ImageProhibitedContent,
+    /// <summary>
+    /// Image generation stopped because of other miscellaneous issue.
+    /// </summary>
+    ImageOther,
+    /// <summary>
+    /// The model was expected to generate an image, but none was generated.
+    /// </summary>
+    NoImage,
+    /// <summary>
+    /// Image generation stopped due to recitation.
+    /// </summary>
+    ImageRecitation,
+    /// <summary>
+    /// The response candidate content was flagged for using an unsupported language.
+    /// </summary>
+    Language,
+    /// <summary>
+    /// Model generated a tool call but no tools were enabled in the request.
+    /// </summary>
+    UnexpectedToolCall,
+    /// <summary>
+    /// Model called too many tools consecutively, thus the system exited execution.
+    /// </summary>
+    TooManyToolCalls,
+    /// <summary>
+    /// Request has at least one thought signature missing.
+    /// </summary>
+    MissingThoughtSignature,
+    /// <summary>
+    /// Finished due to malformed response.
+    /// </summary>
+    MalformedResponse,
   }
 
   /// <summary>
@@ -137,6 +177,16 @@ private static FinishReason ParseFinishReason(string str)
         "PROHIBITED_CONTENT" => Firebase.AI.FinishReason.ProhibitedContent,
         "SPII" => Firebase.AI.FinishReason.SPII,
         "MALFORMED_FUNCTION_CALL" => Firebase.AI.FinishReason.MalformedFunctionCall,
+        "IMAGE_SAFETY" => Firebase.AI.FinishReason.ImageSafety,
+        "IMAGE_PROHIBITED_CONTENT" => Firebase.AI.FinishReason.ImageProhibitedContent,
+        "IMAGE_OTHER" => Firebase.AI.FinishReason.ImageOther,
+        "NO_IMAGE" => Firebase.AI.FinishReason.NoImage,
+        "IMAGE_RECITATION" => Firebase.AI.FinishReason.ImageRecitation,
+        "LANGUAGE" => Firebase.AI.FinishReason.Language,
+        "UNEXPECTED_TOOL_CALL" => Firebase.AI.FinishReason.UnexpectedToolCall,
+        "TOO_MANY_TOOL_CALLS" => Firebase.AI.FinishReason.TooManyToolCalls,
+        "MISSING_THOUGHT_SIGNATURE" => Firebase.AI.FinishReason.MissingThoughtSignature,
+        "MALFORMED_RESPONSE" => Firebase.AI.FinishReason.MalformedResponse,
         _ => Firebase.AI.FinishReason.Unknown,
       };
     }

firebaseai/src/GenerationConfig.cs

@@ -40,6 +40,7 @@ public readonly struct GenerationConfig
     private readonly JsonSchema _responseJsonSchema;
     private readonly List<ResponseModality> _responseModalities;
     private readonly ThinkingConfig? _thinkingConfig;
+    private readonly ImageConfig? _imageConfig;
 
     /// <summary>
     /// Creates a new `GenerationConfig` value.
@@ -168,6 +169,9 @@ public readonly struct GenerationConfig
     /// An error will be returned if this field is set for models that don't
     /// support thinking.
     /// </param>
+    /// <param name="imageConfig">
+    /// Configuration for the aspect ratio and size of generated images.
+    /// </param>
     public GenerationConfig(
         float? temperature = null,
         float? topP = null,
@@ -181,7 +185,8 @@ public GenerationConfig(
         Schema responseSchema = null,
         JsonSchema responseJsonSchema = null,
         IEnumerable<ResponseModality> responseModalities = null,
-        ThinkingConfig? thinkingConfig = null)
+        ThinkingConfig? thinkingConfig = null,
+        ImageConfig? imageConfig = null)
     {
       _temperature = temperature;
       _topP = topP;
@@ -197,6 +202,7 @@ public GenerationConfig(
       _responseModalities = responseModalities != null ?
           new List<ResponseModality>(responseModalities) : null;
       _thinkingConfig = thinkingConfig;
+      _imageConfig = imageConfig;
     }
 
     /// <summary>
@@ -222,7 +228,8 @@ internal Dictionary<string, object> ToJson()
         jsonDict["responseModalities"] =
             _responseModalities.Select(EnumConverters.ResponseModalityToString).ToList();
       }
-      if (_thinkingConfig != null) jsonDict["thinkingConfig"] = _thinkingConfig?.ToJson();
+      if (_thinkingConfig != null) jsonDict["thinkingConfig"] = _thinkingConfig.Value.ToJson();
+      if (_imageConfig != null) jsonDict["imageConfig"] = _imageConfig.Value.ToJson();
 
       return jsonDict;
     }

firebaseai/src/ImageConfig.cs

@@ -0,0 +1,99 @@
+/*
+ * Copyright 2026 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.
+ */
+
+using System.Collections.Generic;
+
+namespace Firebase.AI
+{
+  /// <summary>
+  /// Configuration options for generating images with Gemini models.
+  /// </summary>
+  public readonly struct ImageConfig
+  {
+    /// <summary>
+    /// The aspect ratio of generated images.
+    /// </summary>
+    public readonly struct AspectRatio : System.IEquatable<AspectRatio>
+    {
+      public string Value { get; }
+      public AspectRatio(string value) { Value = value; }
+
+      public static readonly AspectRatio Square1x1 = new AspectRatio("1:1");
+      public static readonly AspectRatio Portrait9x16 = new AspectRatio("9:16");
+      public static readonly AspectRatio Landscape16x9 = new AspectRatio("16:9");
+      public static readonly AspectRatio Portrait3x4 = new AspectRatio("3:4");
+      public static readonly AspectRatio Landscape4x3 = new AspectRatio("4:3");
+      public static readonly AspectRatio Portrait2x3 = new AspectRatio("2:3");
+      public static readonly AspectRatio Landscape3x2 = new AspectRatio("3:2");
+      public static readonly AspectRatio Portrait4x5 = new AspectRatio("4:5");
+      public static readonly AspectRatio Landscape5x4 = new AspectRatio("5:4");
+      public static readonly AspectRatio Portrait1x4 = new AspectRatio("1:4");
+      public static readonly AspectRatio Landscape4x1 = new AspectRatio("4:1");
+      public static readonly AspectRatio Portrait1x8 = new AspectRatio("1:8");
+      public static readonly AspectRatio Landscape8x1 = new AspectRatio("8:1");
+      public static readonly AspectRatio Ultrawide21x9 = new AspectRatio("21:9");
+
+      public override string ToString() => Value;
+
+      public bool Equals(AspectRatio other) => Value == other.Value;
+      public override bool Equals(object obj) => obj is AspectRatio other && Equals(other);
+      public override int GetHashCode() => Value?.GetHashCode() ?? 0;
+
+      public static bool operator ==(AspectRatio left, AspectRatio right) => left.Equals(right);
+      public static bool operator !=(AspectRatio left, AspectRatio right) => !left.Equals(right);
+    }
+
+    /// <summary>
+    /// The size of images to generate.
+    /// </summary>
+    public readonly struct ImageSize : System.IEquatable<ImageSize>
+    {
+      public string Value { get; }
+      public ImageSize(string value) { Value = value; }
+
+      public static readonly ImageSize Size512 = new ImageSize("512");
+      public static readonly ImageSize Size1K = new ImageSize("1K");
+      public static readonly ImageSize Size2K = new ImageSize("2K");
+      public static readonly ImageSize Size4K = new ImageSize("4K");
+
+      public override string ToString() => Value;
+
+      public bool Equals(ImageSize other) => Value == other.Value;
+      public override bool Equals(object obj) => obj is ImageSize other && Equals(other);
+      public override int GetHashCode() => Value?.GetHashCode() ?? 0;
+
+      public static bool operator ==(ImageSize left, ImageSize right) => left.Equals(right);
+      public static bool operator !=(ImageSize left, ImageSize right) => !left.Equals(right);
+    }
+
+    public AspectRatio? AspectRatio { get; }
+    public ImageSize? ImageSize { get; }
+
+    public ImageConfig(AspectRatio? aspectRatio = null, ImageSize? imageSize = null)
+    {
+      AspectRatio = aspectRatio;
+      ImageSize = imageSize;
+    }
+
+    internal Dictionary<string, object> ToJson()
+    {
+      Dictionary<string, object> jsonDict = new();
+      if (AspectRatio?.Value is string aspectRatio) jsonDict["aspectRatio"] = aspectRatio;
+      if (ImageSize?.Value is string imageSize) jsonDict["imageSize"] = imageSize;
+      return jsonDict;
+    }
+  }
+}

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

@@ -171,6 +171,8 @@ protected override void Start()
         TestReadSecureFile,
         // Internal tests for Json parsing, requires using a source library.
         InternalTestBasicReplyShort,
+        InternalTestFinishReasonExpanded,
+        InternalTestImageConfigSerialization,
         InternalTestCitations,
         InternalTestBlockedSafetyWithMessage,
         InternalTestFinishReasonSafetyNoContent,
@@ -1380,6 +1382,59 @@ async Task InternalTestBasicReplyShort()
       ValidateUsageMetadata(response.UsageMetadata, 6, 7, 0, 0, 13);
     }
 
+    // Test that parsing a response with expanded FinishReason works.
+    async Task InternalTestFinishReasonExpanded()
+    {
+      string jsonStr = @"{
+        ""candidates"": [{
+          ""content"": {
+            ""parts"": [{""text"": ""Hello""}],
+            ""role"": ""model""
+          },
+          ""finishReason"": ""IMAGE_SAFETY""
+        }]
+      }";
+      Dictionary<string, object> json = (Dictionary<string, object>)Json.Deserialize(jsonStr);
+      GenerateContentResponse response = GenerateContentResponse.FromJson(json, FirebaseAI.Backend.InternalProvider.VertexAI);
+
+      Assert(""Response missing candidates."", response.Candidates.Any());
+      Candidate candidate = response.Candidates.First();
+      AssertEq(""FinishReason"", candidate.FinishReason, FinishReason.ImageSafety);
+
+      // Test another one
+      jsonStr = @"{
+        ""candidates"": [{
+          ""content"": {""parts"": []},
+          ""finishReason"": ""MALFORMED_RESPONSE""
+        }]
+      }";
+      json = (Dictionary<string, object>)Json.Deserialize(jsonStr);
+      response = GenerateContentResponse.FromJson(json, FirebaseAI.Backend.InternalProvider.VertexAI);
+      candidate = response.Candidates.First();
+      AssertEq(""FinishReason"", candidate.FinishReason, FinishReason.MalformedResponse);
+    }
+
+    // Test that ImageConfig serialization works as expected.
+    Task InternalTestImageConfigSerialization()
+    {
+      var imageConfig = new ImageConfig(ImageConfig.AspectRatio.Landscape16x9, ImageConfig.ImageSize.Size1K);
+      var json = imageConfig.ToJson();
+
+      AssertEq(""ImageConfig.aspectRatio"", json[""aspectRatio""], ""16:9"");
+      AssertEq(""ImageConfig.imageSize"", json[""imageSize""], ""1K"");
+
+      var genConfig = new GenerationConfig(imageConfig: imageConfig);
+      var genJson = genConfig.ToJson();
+
+      Assert(""GenerationConfig missing imageConfig"", genJson.ContainsKey(""imageConfig""));
+      var imageConfigJson = genJson[""imageConfig""] as Dictionary<string, object>;
+      Assert(""imageConfig is not a dictionary"", imageConfigJson != null);
+      AssertEq(""imageConfigJson.aspectRatio"", imageConfigJson[""aspectRatio""], ""16:9"");
+      AssertEq(""imageConfigJson.imageSize"", imageConfigJson[""imageSize""], ""1K"");
+
+      return Task.CompletedTask;
+    }
+
     // Test that parsing a response including Citations works.
     // https://github.com/FirebaseExtended/vertexai-sdk-test-data/blob/main/mock-responses/unary-success-citations.json
     async Task InternalTestCitations()