diff --git a/packages/cli/src/ui/auth/useAuth.ts b/packages/cli/src/ui/auth/useAuth.ts
index 7237ac33d..05f811741 100644
--- a/packages/cli/src/ui/auth/useAuth.ts
+++ b/packages/cli/src/ui/auth/useAuth.ts
@@ -83,12 +83,26 @@ export const useAuthCommand = (
     async (authType: AuthType, credentials?: OpenAICredentials) => {
       try {
         const authTypeScope = getPersistScopeForModelSelection(settings);
+
+        // Persist authType
         settings.setValue(
           authTypeScope,
           'security.auth.selectedType',
           authType,
         );
 
+        // Persist model from ContentGenerator config (handles fallback cases)
+        // This ensures that when syncAfterAuthRefresh falls back to default model,
+        // it gets persisted to settings.json
+        const contentGeneratorConfig = config.getContentGeneratorConfig();
+        if (contentGeneratorConfig?.model) {
+          settings.setValue(
+            authTypeScope,
+            'model.name',
+            contentGeneratorConfig.model,
+          );
+        }
+
         // Only update credentials if not switching to QWEN_OAUTH,
         // so that OpenAI credentials are preserved when switching to QWEN_OAUTH.
         if (authType !== AuthType.QWEN_OAUTH && credentials) {
@@ -106,9 +120,6 @@ export const useAuthCommand = (
               credentials.baseUrl,
             );
           }
-          if (credentials?.model != null) {
-            settings.setValue(authTypeScope, 'model.name', credentials.model);
-          }
         }
       } catch (error) {
         handleAuthFailure(error);
diff --git a/packages/cli/src/utils/modelConfigUtils.ts b/packages/cli/src/utils/modelConfigUtils.ts
index 4a025ed1f..305e50d15 100644
--- a/packages/cli/src/utils/modelConfigUtils.ts
+++ b/packages/cli/src/utils/modelConfigUtils.ts
@@ -120,7 +120,7 @@ export function resolveCliGenerationConfig(
 
   // Log warnings if any
   for (const warning of resolved.warnings) {
-    console.warn(`[modelProviderUtils] ${warning}`);
+    console.warn(warning);
   }
 
   // Resolve OpenAI logging config (CLI-specific, not part of core resolver)
diff --git a/packages/core/src/models/constants.ts b/packages/core/src/models/constants.ts
index fcb1be985..1ef9919a2 100644
--- a/packages/core/src/models/constants.ts
+++ b/packages/core/src/models/constants.ts
@@ -106,15 +106,6 @@ export const QWEN_OAUTH_MODELS: ModelConfig[] = [
     description:
       'The latest Qwen Coder model from Alibaba Cloud ModelStudio (version: qwen3-coder-plus-2025-09-23)',
     capabilities: { vision: false },
-    generationConfig: {
-      samplingParams: {
-        temperature: 0.7,
-        top_p: 0.9,
-        max_tokens: 8192,
-      },
-      timeout: 60000,
-      maxRetries: 3,
-    },
   },
   {
     id: 'vision-model',
@@ -122,14 +113,5 @@ export const QWEN_OAUTH_MODELS: ModelConfig[] = [
     description:
       'The latest Qwen Vision model from Alibaba Cloud ModelStudio (version: qwen3-vl-plus-2025-09-23)',
     capabilities: { vision: true },
-    generationConfig: {
-      samplingParams: {
-        temperature: 0.7,
-        top_p: 0.9,
-        max_tokens: 8192,
-      },
-      timeout: 60000,
-      maxRetries: 3,
-    },
   },
 ];
diff --git a/packages/core/src/models/modelsConfig.test.ts b/packages/core/src/models/modelsConfig.test.ts
index 1b220294e..06896a382 100644
--- a/packages/core/src/models/modelsConfig.test.ts
+++ b/packages/core/src/models/modelsConfig.test.ts
@@ -480,6 +480,91 @@ describe('ModelsConfig', () => {
     expect(gc.apiKeyEnvKey).toBeUndefined();
   });
 
+  it('should use default model for new authType when switching from different authType with env vars', () => {
+    // Simulate cold start with OPENAI env vars (OPENAI_MODEL and OPENAI_API_KEY)
+    // This sets the model in generationConfig but no authType is selected yet
+    const modelsConfig = new ModelsConfig({
+      generationConfig: {
+        model: 'gpt-4o', // From OPENAI_MODEL env var
+        apiKey: 'openai-key-from-env',
+      },
+    });
+
+    // User switches to qwen-oauth via AuthDialog
+    // refreshAuth calls syncAfterAuthRefresh with the current model (gpt-4o)
+    // which doesn't exist in qwen-oauth registry, so it should use default
+    modelsConfig.syncAfterAuthRefresh(AuthType.QWEN_OAUTH, 'gpt-4o');
+
+    const gc = currentGenerationConfig(modelsConfig);
+    // Should use default qwen-oauth model (coder-model), not the OPENAI model
+    expect(gc.model).toBe('coder-model');
+    expect(gc.apiKey).toBe('QWEN_OAUTH_DYNAMIC_TOKEN');
+    expect(gc.apiKeyEnvKey).toBeUndefined();
+  });
+
+  it('should clear manual credentials when switching from USE_OPENAI to QWEN_OAUTH', () => {
+    // User manually set credentials for OpenAI
+    const modelsConfig = new ModelsConfig({
+      initialAuthType: AuthType.USE_OPENAI,
+      generationConfig: {
+        model: 'gpt-4o',
+        apiKey: 'manual-openai-key',
+        baseUrl: 'https://manual.example.com/v1',
+      },
+    });
+
+    // Manually set credentials via updateCredentials
+    modelsConfig.updateCredentials({
+      apiKey: 'manual-openai-key',
+      baseUrl: 'https://manual.example.com/v1',
+      model: 'gpt-4o',
+    });
+
+    // User switches to qwen-oauth
+    // Since authType is not USE_OPENAI, manual credentials should be cleared
+    // and default qwen-oauth model should be applied
+    modelsConfig.syncAfterAuthRefresh(AuthType.QWEN_OAUTH, 'gpt-4o');
+
+    const gc = currentGenerationConfig(modelsConfig);
+    // Should use default qwen-oauth model, not preserve manual OpenAI credentials
+    expect(gc.model).toBe('coder-model');
+    expect(gc.apiKey).toBe('QWEN_OAUTH_DYNAMIC_TOKEN');
+    // baseUrl should be set to qwen-oauth default, not preserved from manual OpenAI config
+    expect(gc.baseUrl).toBe('DYNAMIC_QWEN_OAUTH_BASE_URL');
+    expect(gc.apiKeyEnvKey).toBeUndefined();
+  });
+
+  it('should preserve manual credentials when switching to USE_OPENAI', () => {
+    // User manually set credentials
+    const modelsConfig = new ModelsConfig({
+      initialAuthType: AuthType.USE_OPENAI,
+      generationConfig: {
+        model: 'gpt-4o',
+        apiKey: 'manual-openai-key',
+        baseUrl: 'https://manual.example.com/v1',
+        samplingParams: { temperature: 0.9 },
+      },
+    });
+
+    // Manually set credentials via updateCredentials
+    modelsConfig.updateCredentials({
+      apiKey: 'manual-openai-key',
+      baseUrl: 'https://manual.example.com/v1',
+      model: 'gpt-4o',
+    });
+
+    // User switches to USE_OPENAI (same or different model)
+    // Since authType is USE_OPENAI, manual credentials should be preserved
+    modelsConfig.syncAfterAuthRefresh(AuthType.USE_OPENAI, 'gpt-4o');
+
+    const gc = currentGenerationConfig(modelsConfig);
+    // Should preserve manual credentials
+    expect(gc.model).toBe('gpt-4o');
+    expect(gc.apiKey).toBe('manual-openai-key');
+    expect(gc.baseUrl).toBe('https://manual.example.com/v1');
+    expect(gc.samplingParams?.temperature).toBe(0.9); // Preserved from initial config
+  });
+
   it('should maintain consistency between currentModelId and _generationConfig.model after initialization', () => {
     const modelProvidersConfig: ModelProvidersConfig = {
       openai: [
diff --git a/packages/core/src/models/modelsConfig.ts b/packages/core/src/models/modelsConfig.ts
index 1c88903c2..36435143f 100644
--- a/packages/core/src/models/modelsConfig.ts
+++ b/packages/core/src/models/modelsConfig.ts
@@ -600,7 +600,7 @@ export class ModelsConfig {
 
     // If credentials were manually set, don't apply modelProvider defaults
     // Just update the authType and preserve the manually set credentials
-    if (preserveManualCredentials) {
+    if (preserveManualCredentials && authType === AuthType.USE_OPENAI) {
       this.strictModelProviderSelection = false;
       this.currentAuthType = authType;
       if (modelId) {
@@ -621,7 +621,17 @@ export class ModelsConfig {
         this.applyResolvedModelDefaults(resolved);
       }
     } else {
+      // If the provided modelId doesn't exist in the registry for the new authType,
+      // use the default model for that authType instead of keeping the old model.
+      // This handles the case where switching from one authType (e.g., OPENAI with
+      // env vars) to another (e.g., qwen-oauth) - we should use the default model
+      // for the new authType, not the old model.
       this.currentAuthType = authType;
+      const defaultModel =
+        this.modelRegistry.getDefaultModelForAuthType(authType);
+      if (defaultModel) {
+        this.applyResolvedModelDefaults(defaultModel);
+      }
     }
   }
 
diff --git a/packages/sdk-typescript/src/utils/cliPath.ts b/packages/sdk-typescript/src/utils/cliPath.ts
index e4a7924bc..fb795ec80 100644
--- a/packages/sdk-typescript/src/utils/cliPath.ts
+++ b/packages/sdk-typescript/src/utils/cliPath.ts
@@ -125,8 +125,9 @@ function normalizeForRegex(dirPath: string): string {
 function tryResolveCliFromImportMeta(): string | null {
   try {
     if (typeof import.meta !== 'undefined' && import.meta.url) {
-      const cliUrl = new URL('./cli/cli.js', import.meta.url);
-      const cliPath = fileURLToPath(cliUrl);
+      const currentFilePath = fileURLToPath(import.meta.url);
+      const currentDir = path.dirname(currentFilePath);
+      const cliPath = path.join(currentDir, 'cli', 'cli.js');
       if (fs.existsSync(cliPath)) {
         return cliPath;
       }