feat(js/plugins/google-genai): serviceTier support for googleAI

js/plugins/google-genai/src/common/types.ts

@@ -1242,6 +1242,8 @@ export declare interface GenerateContentRequest {
   tools?: Tool[];
   /** Optional. This config is shared for all tools provided in the request. */
   toolConfig?: ToolConfig;
+  /** Optional. Service tier (e.g. 'standard', 'flex', or 'priority'). */
+  serviceTier?: string;
 }
 
 /**

js/plugins/google-genai/src/googleai/gemini.ts

@@ -262,6 +262,10 @@ export const GeminiConfigSchema = GenerationCommonConfigSchema.extend({
       GenerationCommonConfigDescriptions.topP + ' The default value is 0.95.'
     )
     .optional(),
+  serviceTier: z
+    .union([z.enum(['standard', 'flex', 'priority']), z.string()])
+    .describe('Service tier for the Gemini API.')
+    .optional(),
   thinkingConfig: z
     .object({
       includeThoughts: z
@@ -722,6 +726,7 @@ export function defineModel(
         urlContext,
         tools: toolsFromConfig,
         retrievalConfig,
+        serviceTier,
         ...restOfConfigOptions
       } = requestOptions;
 
@@ -845,6 +850,7 @@ export function defineModel(
           (setting) => setting.category !== 'HARM_CATEGORY_UNSPECIFIED'
         ) as SafetySetting[],
         contents: messages.map((message) => toGeminiMessage(message, ref)),
+        serviceTier,
       };
 
       const generateApiKey = calculateApiKey(

js/plugins/google-genai/tests/googleai/gemini_test.ts

@@ -496,6 +496,23 @@ describe('Google AI Gemini', () => {
         });
       });
 
+      it('passes serviceTier to the API', async () => {
+        const model = defineModel('gemini-flash-latest', defaultPluginOptions);
+        mockFetchResponse(defaultApiResponse);
+        const request: GenerateRequest<typeof GeminiConfigSchema> = {
+          ...minimalRequest,
+          config: {
+            serviceTier: 'flex',
+          },
+        };
+        await model.run(request);
+
+        const apiRequest: GenerateContentRequest = JSON.parse(
+          fetchStub.lastCall.args[1].body
+        );
+        assert.strictEqual(apiRequest.serviceTier, 'flex');
+      });
+
       it('passes imageConfig to the API', async () => {
         const model = defineModel(
           'gemini-2.5-flash-image',

js/testapps/basic-gemini/src/index.ts

@@ -93,6 +93,18 @@ ai.defineFlow('basic-hi', async () => {
   return text;
 });
 
+ai.defineFlow('basic-hi-flex-tier', async () => {
+  const { text } = await ai.generate({
+    model: googleAI.model('gemini-flash-lite-latest'),
+    prompt: 'You are a helpful AI assistant named Walt, say hello',
+    config: {
+      serviceTier: 'flex', // or 'standard' or 'priority'
+    },
+  });
+
+  return text;
+});
+
 ai.defineFlow('basic-hi-with-retry', async () => {
   const { text } = await ai.generate({
     model: googleAI.model('gemini-pro-latest'),