[AI] Add support for thinkingSummaries and thoughtSignatures (#7272)

Added support for returning [thought
summaries](https://ai.google.dev/gemini-api/docs/thinking#summaries)
when using thinking-compatible models.

Additionally, it adds support for automatic handling of
`thoughtSignatures`.

---------

Co-authored-by: gemini-code-assist[bot] <176961590+gemini-code-assist[bot]@users.noreply.github.com>

Author: rlazo

firebase-ai/CHANGELOG.md

@@ -1,4 +1,6 @@
 # Unreleased
+* [feature] Added support for returning thought summaries, which are synthesized
+  versions of a model's internal reasoning process.
 * [fixed] Fixed an issue causing the accessor methods in `GenerateContentResponse` to throw an exception
   when the response contained no candidates.
 * [changed] Added better description for requests which fail due to the Gemini API not being

firebase-ai/api.txt

@@ -217,6 +217,8 @@ package com.google.firebase.ai.type {
     ctor public CodeExecutionResultPart(String outcome, String output);
     method public String getOutcome();
     method public String getOutput();
+    method public boolean isThought();
+    property public boolean isThought;
     property public final String outcome;
     property public final String output;
   }
@@ -292,14 +294,18 @@ package com.google.firebase.ai.type {
     ctor public ExecutableCodePart(String language, String code);
     method public String getCode();
     method public String getLanguage();
+    method public boolean isThought();
     property public final String code;
+    property public boolean isThought;
     property public final String language;
   }
 
   public final class FileDataPart implements com.google.firebase.ai.type.Part {
     ctor public FileDataPart(String uri, String mimeType);
     method public String getMimeType();
     method public String getUri();
+    method public boolean isThought();
+    property public boolean isThought;
     property public final String mimeType;
     property public final String uri;
   }
@@ -334,8 +340,10 @@ package com.google.firebase.ai.type {
     method public java.util.Map<java.lang.String,kotlinx.serialization.json.JsonElement> getArgs();
     method public String? getId();
     method public String getName();
+    method public boolean isThought();
     property public final java.util.Map<java.lang.String,kotlinx.serialization.json.JsonElement> args;
     property public final String? id;
+    property public boolean isThought;
     property public final String name;
   }
 
@@ -364,7 +372,9 @@ package com.google.firebase.ai.type {
     method public String? getId();
     method public String getName();
     method public kotlinx.serialization.json.JsonObject getResponse();
+    method public boolean isThought();
     property public final String? id;
+    property public boolean isThought;
     property public final String name;
     property public final kotlinx.serialization.json.JsonObject response;
   }
@@ -376,12 +386,14 @@ package com.google.firebase.ai.type {
     method public java.util.List<com.google.firebase.ai.type.InlineDataPart> getInlineDataParts();
     method public com.google.firebase.ai.type.PromptFeedback? getPromptFeedback();
     method public String? getText();
+    method public String? getThoughtSummary();
     method public com.google.firebase.ai.type.UsageMetadata? getUsageMetadata();
     property public final java.util.List<com.google.firebase.ai.type.Candidate> candidates;
     property public final java.util.List<com.google.firebase.ai.type.FunctionCallPart> functionCalls;
     property public final java.util.List<com.google.firebase.ai.type.InlineDataPart> inlineDataParts;
     property public final com.google.firebase.ai.type.PromptFeedback? promptFeedback;
     property public final String? text;
+    property public final String? thoughtSummary;
     property public final com.google.firebase.ai.type.UsageMetadata? usageMetadata;
   }
 
@@ -552,7 +564,9 @@ package com.google.firebase.ai.type {
   public final class ImagePart implements com.google.firebase.ai.type.Part {
     ctor public ImagePart(android.graphics.Bitmap image);
     method public android.graphics.Bitmap getImage();
+    method public boolean isThought();
     property public final android.graphics.Bitmap image;
+    property public boolean isThought;
   }
 
   @com.google.firebase.ai.type.PublicPreviewAPI public final class ImagenAspectRatio {
@@ -777,7 +791,9 @@ package com.google.firebase.ai.type {
     ctor public InlineDataPart(byte[] inlineData, String mimeType);
     method public byte[] getInlineData();
     method public String getMimeType();
+    method public boolean isThought();
     property public final byte[] inlineData;
+    property public boolean isThought;
     property public final String mimeType;
   }
 
@@ -886,6 +902,8 @@ package com.google.firebase.ai.type {
   }
 
   public interface Part {
+    method public boolean isThought();
+    property public abstract boolean isThought;
   }
 
   public final class PartKt {
@@ -1146,6 +1164,8 @@ package com.google.firebase.ai.type {
   public final class TextPart implements com.google.firebase.ai.type.Part {
     ctor public TextPart(String text);
     method public String getText();
+    method public boolean isThought();
+    property public boolean isThought;
     property public final String text;
   }
 
@@ -1155,6 +1175,7 @@ package com.google.firebase.ai.type {
   public static final class ThinkingConfig.Builder {
     ctor public ThinkingConfig.Builder();
     method public com.google.firebase.ai.type.ThinkingConfig build();
+    method public com.google.firebase.ai.type.ThinkingConfig.Builder setIncludeThoughts(boolean includeThoughts);
     method public com.google.firebase.ai.type.ThinkingConfig.Builder setThinkingBudget(int thinkingBudget);
   }
 

firebase-ai/src/main/kotlin/com/google/firebase/ai/type/GenerateContentResponse.kt

@@ -34,42 +34,66 @@ public class GenerateContentResponse(
   /**
    * Convenience field representing all the text parts in the response as a single string.
    *
-   * The value is null if the response contains no [candidates].
+   * The value is null if the response contains no valid text [candidates].
+   *
+   * Any part that's marked as a thought will be ignored. Learn more about
+   * [thinking](https://firebase.google.com/docs/ai-logic/thinking?api=dev).
    */
   public val text: String? by lazy {
-    candidates.firstOrNull()?.content?.parts?.filterIsInstance<TextPart>()?.joinToString(" ") {
-      it.text
-    }
+    val parts = candidates.firstOrNull()?.nonThoughtParts()?.filterIsInstance<TextPart>()
+    if (parts.isNullOrEmpty()) return@lazy null
+    parts.joinToString(" ") { it.text }
   }
 
   /**
    * Convenience field to list all the [FunctionCallPart]s in the response.
    *
    * The value is an empty list if the response contains no [candidates].
+   *
+   * Any part that's marked as a thought will be ignored. Learn more about
+   * [thinking](https://firebase.google.com/docs/ai-logic/thinking?api=dev).
    */
   public val functionCalls: List<FunctionCallPart> by lazy {
-    candidates.firstOrNull()?.content?.parts?.filterIsInstance<FunctionCallPart>().orEmpty()
+    candidates.firstOrNull()?.nonThoughtParts()?.filterIsInstance<FunctionCallPart>().orEmpty()
+  }
+
+  /**
+   * Convenience field representing all the text parts in the response that are marked as thoughts
+   * as a single string, if they exists.
+   *
+   * Learn more about [thinking](https://firebase.google.com/docs/ai-logic/thinking?api=dev).
+   */
+  public val thoughtSummary: String? by lazy {
+    candidates.firstOrNull()?.thoughtParts()?.filterIsInstance<TextPart>()?.joinToString(" ") {
+      it.text
+    }
   }
 
   /**
-   * Convenience field representing all the [InlineDataPart]s in the first candidate, if they exist.
+   * Convenience field representing all the [InlineDataPart]s in the first candidate.
    *
    * This also includes any [ImagePart], but they will be represented as [InlineDataPart] instead.
    *
    * The value is an empty list if the response contains no [candidates].
+   *
+   * Any part that's marked as a thought will be ignored. Learn more about
+   * [thinking](https://firebase.google.com/docs/ai-logic/thinking?api=dev).
    */
   public val inlineDataParts: List<InlineDataPart> by lazy {
     candidates
       .firstOrNull()
-      ?.content
-      ?.parts
+      ?.nonThoughtParts()
       ?.let { parts ->
         parts.filterIsInstance<ImagePart>().map { it.toInlineDataPart() } +
           parts.filterIsInstance<InlineDataPart>()
       }
       .orEmpty()
   }
 
+  private fun Candidate.thoughtParts(): List<Part> = content.parts.filter { it.isThought }
+
+  private fun Candidate.nonThoughtParts(): List<Part> = content.parts.filter { !it.isThought }
+
   @Serializable
   internal data class Internal(
     val candidates: List<Candidate.Internal>? = null,