added release channel plumbing and auto 2.5 and 3 parity for deprecated auto modes.

packages/core/src/availability/policyHelpers.test.ts

@@ -37,7 +37,11 @@ const createMockConfig = (overrides: Partial<Config> = {}): Config => {
       return useGemini31 && authType === AuthType.USE_GEMINI;
     },
     getContentGeneratorConfig: () => ({ authType: undefined }),
+    getHasAccessToPreviewModel: () => true,
     getMaxAttemptsPerTurn: () => 3,
+    getExperimentalDynamicModelConfiguration: () => false,
+    getReleaseChannel: () => 'preview',
+    modelConfigService: new ModelConfigService(DEFAULT_MODEL_CONFIGS),
     ...overrides,
   } as unknown as Config;
   return config;
@@ -186,6 +190,7 @@ describe('policyHelpers', () => {
     const testCases = [
       { name: 'Default Auto', model: DEFAULT_GEMINI_MODEL_AUTO },
       { name: 'Gemini 3 Auto', model: 'auto-gemini-3' },
+      { name: 'Unified Auto', model: 'auto' },
       { name: 'Flash Lite', model: DEFAULT_GEMINI_FLASH_LITE_MODEL },
       {
         name: 'Gemini 3 Auto (3.1 Enabled)',
@@ -214,7 +219,18 @@ describe('policyHelpers', () => {
     ];
 
     testCases.forEach(
-      ({ name, model, useGemini31, hasAccess, authType, wrapsAround }) => {
+      ({
+        name,
+        model,
+        useGemini31,
+        hasAccess,
+        authType,
+        wrapsAround,
+        ...rest
+      }) => {
+        const releaseChannel = (rest as Record<string, unknown>)[
+          'releaseChannel'
+        ] as string | undefined;
         it(`achieves parity for: ${name}`, () => {
           const createBaseConfig = (dynamic: boolean) =>
             createMockConfig({
@@ -224,6 +240,7 @@ describe('policyHelpers', () => {
               getGemini31FlashLiteLaunchedSync: () => false,
               getHasAccessToPreviewModel: () => hasAccess ?? true,
               getContentGeneratorConfig: () => ({ authType }),
+              getReleaseChannel: () => releaseChannel ?? 'preview',
               modelConfigService: new ModelConfigService(DEFAULT_MODEL_CONFIGS),
             });
 

packages/core/src/availability/policyHelpers.ts

@@ -71,6 +71,7 @@ export function resolvePolicyChain(
       useGemini3_1: useGemini31,
       useGemini3_1FlashLite: useGemini31FlashLite,
       useCustomTools: useCustomToolModel,
+      releaseChannel: config.getReleaseChannel?.(),
     };
 
     if (resolvedModel === DEFAULT_GEMINI_FLASH_LITE_MODEL) {

packages/core/src/config/config.ts

@@ -442,6 +442,7 @@ export interface ExtensionInstallMetadata {
   allowPreRelease?: boolean;
 }
 
+import { getChannelFromVersion } from '../utils/channel.js';
 import { DEFAULT_MAX_ATTEMPTS } from '../utils/retry.js';
 import {
   DEFAULT_FILE_FILTERING_OPTIONS,
@@ -2784,6 +2785,10 @@ export class Config implements McpContext, AgentLoopContext {
     return this.dynamicModelConfiguration;
   }
 
+  getReleaseChannel(): string {
+    return getChannelFromVersion(this._clientVersion);
+  }
+
   getPendingIncludeDirectories(): string[] {
     return this.pendingIncludeDirectories;
   }

packages/core/src/config/defaultModelConfigs.ts

@@ -387,6 +387,18 @@ export const DEFAULT_MODEL_CONFIGS: ModelConfigServiceConfig = {
       isVisible: false,
       features: { thinking: false, multimodalToolUse: false },
     },
+    'auto-gemini-3': {
+      tier: 'auto',
+      family: 'gemini-3',
+      isPreview: true,
+      isVisible: false,
+    },
+    'auto-gemini-2.5': {
+      tier: 'auto',
+      family: 'gemini-2.5',
+      isPreview: false,
+      isVisible: false,
+    },
   },
   modelIdResolutions: {
     'gemma-4-31b-it': {
@@ -491,6 +503,23 @@ export const DEFAULT_MODEL_CONFIGS: ModelConfigServiceConfig = {
         },
       ],
     },
+    'auto-gemini-3': {
+      default: 'gemini-3-pro-preview',
+      contexts: [
+        { condition: { hasAccessToPreview: false }, target: 'gemini-2.5-pro' },
+        {
+          condition: { useGemini3_1: true, useCustomTools: true },
+          target: 'gemini-3.1-pro-preview-customtools',
+        },
+        {
+          condition: { useGemini3_1: true },
+          target: 'gemini-3.1-pro-preview',
+        },
+      ],
+    },
+    'auto-gemini-2.5': {
+      default: 'gemini-2.5-pro',
+    },
   },
   classifierIdResolutions: {
     flash: {

packages/core/src/config/models.ts

@@ -49,6 +49,7 @@ export interface IModelConfigService {
 export interface ModelCapabilityContext {
   readonly modelConfigService: IModelConfigService;
   getExperimentalDynamicModelConfiguration(): boolean;
+  getReleaseChannel?(): string;
 }
 
 export const PREVIEW_GEMINI_MODEL = 'gemini-3-pro-preview';
@@ -125,6 +126,7 @@ export function resolveModel(
       useGemini3_1FlashLite,
       useCustomTools: useCustomToolModel,
       hasAccessToPreview,
+      releaseChannel: config.getReleaseChannel?.(),
     });
 
     if (!hasAccessToPreview && isPreviewModel(resolved, config)) {