feat: add support for gemini 3.1 flash-lite

Author: NachoVazquez

packages/typescript/ai-gemini/src/adapters/summarize.ts

@@ -21,6 +21,7 @@ export interface GeminiSummarizeConfig extends GeminiClientConfig {}
  * Available Gemini models for summarization
  */
 export const GeminiSummarizeModels = [
+  'gemini-3.1-flash-lite',
   'gemini-2.0-flash',
   'gemini-1.5-flash',
   'gemini-1.5-pro',

packages/typescript/ai-gemini/src/model-meta.ts

@@ -228,6 +228,43 @@ const GEMINI_3_1_FLASH_IMAGE = {
     GeminiThinkingOptions
 >
 
+const GEMINI_3_1_FLASH_LITE = {
+  name: 'gemini-3.1-flash-lite',
+  max_input_tokens: 1_048_576,
+  max_output_tokens: 65_536,
+  knowledge_cutoff: '2025-01-01',
+  supports: {
+    input: ['text', 'image', 'audio', 'video', 'document'],
+    output: ['text'],
+    capabilities: [
+      'batch_api',
+      'caching',
+      'code_execution',
+      'file_search',
+      'function_calling',
+      'search_grounding',
+      'structured_output',
+      'thinking',
+      'url_context',
+    ],
+  },
+  pricing: {
+    input: {
+      normal: 0.25,
+    },
+    output: {
+      normal: 1.5,
+    },
+  },
+} as const satisfies ModelMeta<
+  GeminiToolConfigOptions &
+    GeminiSafetyOptions &
+    GeminiCommonConfigOptions &
+    GeminiCachedContentOptions &
+    GeminiStructuredOutputOptions &
+    GeminiThinkingOptions
+>
+
 const GEMINI_2_5_PRO = {
   name: 'gemini-2.5-pro',
   max_input_tokens: 1_048_576,
@@ -894,6 +931,7 @@ export const GEMINI_MODELS = [
   GEMINI_3_1_PRO.name,
   GEMINI_3_PRO.name,
   GEMINI_3_FLASH.name,
+  GEMINI_3_1_FLASH_LITE.name,
   GEMINI_2_5_PRO.name,
   GEMINI_2_5_FLASH.name,
   GEMINI_2_5_FLASH_PREVIEW.name,
@@ -1005,6 +1043,12 @@ export type GeminiChatModelProviderOptionsByName = {
     GeminiStructuredOutputOptions &
     GeminiThinkingOptions &
     GeminiThinkingAdvancedOptions
+  [GEMINI_3_1_FLASH_LITE.name]: GeminiToolConfigOptions &
+    GeminiSafetyOptions &
+    GeminiCommonConfigOptions &
+    GeminiCachedContentOptions &
+    GeminiStructuredOutputOptions &
+    GeminiThinkingOptions
   [GEMINI_2_5_PRO.name]: GeminiToolConfigOptions &
     GeminiSafetyOptions &
     GeminiCommonConfigOptions &
@@ -1066,6 +1110,7 @@ export type GeminiModelInputModalitiesByName = {
   [GEMINI_3_1_PRO.name]: typeof GEMINI_3_1_PRO.supports.input
   [GEMINI_3_PRO.name]: typeof GEMINI_3_PRO.supports.input
   [GEMINI_3_FLASH.name]: typeof GEMINI_3_FLASH.supports.input
+  [GEMINI_3_1_FLASH_LITE.name]: typeof GEMINI_3_1_FLASH_LITE.supports.input
   [GEMINI_2_5_PRO.name]: typeof GEMINI_2_5_PRO.supports.input
   [GEMINI_2_5_FLASH_LITE.name]: typeof GEMINI_2_5_FLASH_LITE.supports.input
   [GEMINI_2_5_FLASH_LITE_PREVIEW.name]: typeof GEMINI_2_5_FLASH_LITE_PREVIEW.supports.input

packages/typescript/ai-gemini/tests/model-meta.test.ts

@@ -151,6 +151,28 @@ describe('Gemini Model Provider Options Type Assertions', () => {
       // Should have base options
       expectTypeOf<Options>().toExtend<BaseOptions>()
     })
+
+    it('gemini-3.1-flash-lite should support thinking options', () => {
+      type Model = 'gemini-3.1-flash-lite'
+      type Options = GeminiChatModelProviderOptionsByName[Model]
+
+      // Should have thinking options
+      expectTypeOf<Options>().toExtend<GeminiThinkingOptions>()
+
+      // Should have structured output options
+      expectTypeOf<Options>().toExtend<GeminiStructuredOutputOptions>()
+
+      // Should have base options
+      expectTypeOf<Options>().toExtend<BaseOptions>()
+
+      // Verify specific properties exist
+      expectTypeOf<Options>().toHaveProperty('generationConfig')
+      expectTypeOf<Options>().toHaveProperty('safetySettings')
+      expectTypeOf<Options>().toHaveProperty('toolConfig')
+      expectTypeOf<Options>().toHaveProperty('cachedContent')
+      expectTypeOf<Options>().toHaveProperty('responseMimeType')
+      expectTypeOf<Options>().toHaveProperty('responseSchema')
+    })
   })
 
   describe('Models WITHOUT thinking support', () => {
@@ -195,6 +217,7 @@ describe('Gemini Model Provider Options Type Assertions', () => {
 
       expectTypeOf<'gemini-3-pro-preview'>().toExtend<Keys>()
       expectTypeOf<'gemini-3-flash-preview'>().toExtend<Keys>()
+      expectTypeOf<'gemini-3.1-flash-lite'>().toExtend<Keys>()
       expectTypeOf<'gemini-2.5-pro'>().toExtend<Keys>()
       expectTypeOf<'gemini-2.5-flash'>().toExtend<Keys>()
       expectTypeOf<'gemini-2.5-flash-preview-09-2025'>().toExtend<Keys>()
@@ -244,6 +267,9 @@ describe('Gemini Model Provider Options Type Assertions', () => {
       expectTypeOf<
         GeminiChatModelProviderOptionsByName['gemini-2.5-flash-lite-preview-09-2025']
       >().toHaveProperty('safetySettings')
+      expectTypeOf<
+        GeminiChatModelProviderOptionsByName['gemini-3.1-flash-lite']
+      >().toHaveProperty('safetySettings')
       expectTypeOf<
         GeminiChatModelProviderOptionsByName['gemini-2.0-flash']
       >().toHaveProperty('safetySettings')
@@ -274,6 +300,9 @@ describe('Gemini Model Provider Options Type Assertions', () => {
       expectTypeOf<
         GeminiChatModelProviderOptionsByName['gemini-2.5-flash-lite-preview-09-2025']
       >().toHaveProperty('toolConfig')
+      expectTypeOf<
+        GeminiChatModelProviderOptionsByName['gemini-3.1-flash-lite']
+      >().toHaveProperty('toolConfig')
       expectTypeOf<
         GeminiChatModelProviderOptionsByName['gemini-2.0-flash']
       >().toHaveProperty('toolConfig')
@@ -304,6 +333,9 @@ describe('Gemini Model Provider Options Type Assertions', () => {
       expectTypeOf<
         GeminiChatModelProviderOptionsByName['gemini-2.5-flash-lite-preview-09-2025']
       >().toHaveProperty('cachedContent')
+      expectTypeOf<
+        GeminiChatModelProviderOptionsByName['gemini-3.1-flash-lite']
+      >().toHaveProperty('cachedContent')
       expectTypeOf<
         GeminiChatModelProviderOptionsByName['gemini-2.0-flash']
       >().toHaveProperty('cachedContent')
@@ -336,6 +368,9 @@ describe('Gemini Model Provider Options Type Assertions', () => {
       expectTypeOf<
         GeminiChatModelProviderOptionsByName['gemini-2.5-flash-lite-preview-09-2025']
       >().toExtend<GeminiThinkingOptions>()
+      expectTypeOf<
+        GeminiChatModelProviderOptionsByName['gemini-3.1-flash-lite']
+      >().toExtend<GeminiThinkingOptions>()
     })
 
     it('models without thinking should NOT extend GeminiThinkingOptions', () => {
@@ -369,6 +404,9 @@ describe('Gemini Model Provider Options Type Assertions', () => {
       expectTypeOf<
         GeminiChatModelProviderOptionsByName['gemini-2.5-flash-lite-preview-09-2025']
       >().toExtend<GeminiStructuredOutputOptions>()
+      expectTypeOf<
+        GeminiChatModelProviderOptionsByName['gemini-3.1-flash-lite']
+      >().toExtend<GeminiStructuredOutputOptions>()
       expectTypeOf<
         GeminiChatModelProviderOptionsByName['gemini-2.0-flash']
       >().toExtend<GeminiStructuredOutputOptions>()
@@ -387,7 +425,9 @@ describe('Gemini Model Provider Options Type Assertions', () => {
  *
  * Models with full multimodal (text + image + audio + video + document):
  * - gemini-3-pro-preview
+ * - gemini-3-flash-preview
  * - gemini-2.5-pro
+ * - gemini-3.1-flash-lite
  * - gemini-2.5-flash-lite (and preview)
  *
  * Models with limited multimodal (text + image + audio + video, NO document):
@@ -439,6 +479,19 @@ describe('Gemini Model Input Modality Type Assertions', () => {
     })
   })
 
+  describe('gemini-3.1-flash-lite (full multimodal)', () => {
+    type Modalities = GeminiModelInputModalitiesByName['gemini-3.1-flash-lite']
+    type Message = ConstrainedModelMessage<Modalities>
+
+    it('should allow all content part types', () => {
+      expectTypeOf<MessageWithContent<TextPart>>().toExtend<Message>()
+      expectTypeOf<MessageWithContent<ImagePart>>().toExtend<Message>()
+      expectTypeOf<MessageWithContent<AudioPart>>().toExtend<Message>()
+      expectTypeOf<MessageWithContent<VideoPart>>().toExtend<Message>()
+      expectTypeOf<MessageWithContent<DocumentPart>>().toExtend<Message>()
+    })
+  })
+
   describe('gemini-2.5-flash-lite (full multimodal)', () => {
     type Modalities = GeminiModelInputModalitiesByName['gemini-2.5-flash-lite']
     type Message = ConstrainedModelMessage<Modalities>