[Firebase AI] Add thought summary and signature support

Author: andrewheard

common/api-review/ai.api.md

@@ -208,6 +208,8 @@ export interface EnhancedGenerateContentResponse extends GenerateContentResponse
     functionCalls: () => FunctionCall[] | undefined;
     inlineDataParts: () => InlineDataPart[] | undefined;
     text: () => string;
+    // (undocumented)
+    thoughtSummary: () => string | undefined;
 }
 
 // @public
@@ -240,6 +242,10 @@ export interface FileDataPart {
     inlineData?: never;
     // (undocumented)
     text?: never;
+    // (undocumented)
+    thought?: boolean;
+    // (undocumented)
+    thoughtSignature?: string;
 }
 
 // @public
@@ -294,6 +300,10 @@ export interface FunctionCallPart {
     inlineData?: never;
     // (undocumented)
     text?: never;
+    // (undocumented)
+    thought?: boolean;
+    // (undocumented)
+    thoughtSignature?: string;
 }
 
 // @public
@@ -326,6 +336,10 @@ export interface FunctionResponsePart {
     inlineData?: never;
     // (undocumented)
     text?: never;
+    // (undocumented)
+    thought?: boolean;
+    // (undocumented)
+    thoughtSignature?: string;
 }
 
 // @public
@@ -691,6 +705,10 @@ export interface InlineDataPart {
     inlineData: GenerativeContentBlob;
     // (undocumented)
     text?: never;
+    // (undocumented)
+    thought?: boolean;
+    // (undocumented)
+    thoughtSignature?: string;
     videoMetadata?: VideoMetadata;
 }
 
@@ -957,10 +975,15 @@ export interface TextPart {
     inlineData?: never;
     // (undocumented)
     text: string;
+    // (undocumented)
+    thought?: boolean;
+    // (undocumented)
+    thoughtSignature?: string;
 }
 
 // @public
 export interface ThinkingConfig {
+    includeThoughts?: boolean;
     thinkingBudget?: number;
 }
 

packages/ai/src/requests/response-helpers.ts

@@ -78,7 +78,7 @@ export function addHelpers(
           }
         );
       }
-      return getText(response);
+      return getText(response, false);
     } else if (response.promptFeedback) {
       throw new AIError(
         AIErrorCode.RESPONSE_ERROR,
@@ -160,13 +160,19 @@ export function addHelpers(
 }
 
 /**
- * Returns all text found in all parts of first candidate.
+ * Returns all text from the first candidate's parts, filtering by whether they
+ * are part of the model's 'thought' process.
+ *
+ * @param response - The {@link GenerateContentResponse} from which to extract text.
+ * @param isThought - If `true`, extracts text from `thought` parts of the response,
+ * which represent the model's internal reasoning. If `false`, extracts text from
+ * regular response parts.
  */
-export function getText(response: GenerateContentResponse): string {
+export function getText(response: GenerateContentResponse, isThought: boolean): string {
   const textStrings = [];
   if (response.candidates?.[0].content?.parts) {
     for (const part of response.candidates?.[0].content?.parts) {
-      if (part.text) {
+      if (part.text && (part.thought ?? false) === isThought) {
         textStrings.push(part.text);
       }
     }

packages/ai/src/types/content.ts

@@ -47,6 +47,8 @@ export interface TextPart {
   inlineData?: never;
   functionCall?: never;
   functionResponse?: never;
+  thought?: boolean;
+  thoughtSignature?: string;
 }
 
 /**
@@ -62,6 +64,8 @@ export interface InlineDataPart {
    * Applicable if `inlineData` is a video.
    */
   videoMetadata?: VideoMetadata;
+  thought?: boolean;
+  thoughtSignature?: string;
 }
 
 /**
@@ -90,6 +94,8 @@ export interface FunctionCallPart {
   inlineData?: never;
   functionCall: FunctionCall;
   functionResponse?: never;
+  thought?: boolean;
+  thoughtSignature?: string;
 }
 
 /**
@@ -101,6 +107,8 @@ export interface FunctionResponsePart {
   inlineData?: never;
   functionCall?: never;
   functionResponse: FunctionResponse;
+  thought?: boolean;
+  thoughtSignature?: string;
 }
 
 /**
@@ -113,6 +121,8 @@ export interface FileDataPart {
   functionCall?: never;
   functionResponse?: never;
   fileData: FileData;
+  thought?: boolean;
+  thoughtSignature?: string;
 }
 
 /**

packages/ai/src/types/requests.ts

@@ -294,4 +294,13 @@ export interface ThinkingConfig {
    * feature or if the specified budget is not within the model's supported range.
    */
   thinkingBudget?: number;
+
+  /**
+   * Whether to include "thought summaries" in the model's response.
+   *
+   * Thought summaries provide a brief overview of the model's internal thinking process,
+   * offering insight into how it arrived at the final answer. This can be useful for
+   * debugging, understanding the model's reasoning, and verifying its accuracy.
+   */
+  includeThoughts?: boolean;
 }

packages/ai/src/types/responses.ts

@@ -69,6 +69,7 @@ export interface EnhancedGenerateContentResponse
    */
   inlineDataParts: () => InlineDataPart[] | undefined;
   functionCalls: () => FunctionCall[] | undefined;
+  thoughtSummary: () => string | undefined;
 }
 
 /**