diff --git a/packages/cli/src/zed-integration/zedIntegration.ts b/packages/cli/src/zed-integration/zedIntegration.ts
index afd5975b63..868fbe68d2 100644
--- a/packages/cli/src/zed-integration/zedIntegration.ts
+++ b/packages/cli/src/zed-integration/zedIntegration.ts
@@ -25,6 +25,9 @@ import {
   MCPServerConfig,
   DiscoveredMCPTool,
   StreamEventType,
+  DEFAULT_GEMINI_MODEL,
+  DEFAULT_GEMINI_MODEL_AUTO,
+  DEFAULT_GEMINI_FLASH_MODEL,
 } from '@google/gemini-cli-core';
 import * as acp from './acp.js';
 import { AcpFileSystemService } from './fileSystemService.js';
@@ -41,6 +44,19 @@ import type { Extension } from '../config/extension.js';
 import type { CliArgs } from '../config/config.js';
 import { loadCliConfig } from '../config/config.js';
 
+/**
+ * Resolves the model to use based on the current configuration.
+ *
+ * If the model is set to "auto", it will use the flash model if in fallback
+ * mode, otherwise it will use the default model.
+ */
+export function resolveModel(model: string, isInFallbackMode: boolean): string {
+  if (model === DEFAULT_GEMINI_MODEL_AUTO) {
+    return isInFallbackMode ? DEFAULT_GEMINI_FLASH_MODEL : DEFAULT_GEMINI_MODEL;
+  }
+  return model;
+}
+
 export async function runZedIntegration(
   config: Config,
   settings: LoadedSettings,
@@ -255,7 +271,7 @@ class Session {
 
       try {
         const responseStream = await chat.sendMessageStream(
-          this.config.getModel(),
+          resolveModel(this.config.getModel(), this.config.isInFallbackMode()),
           {
             message: nextMessage?.parts ?? [],
             config: {