diff --git a/integration-tests/acp-integration.test.ts b/integration-tests/acp-integration.test.ts
index b89292d87..7b989e4c7 100644
--- a/integration-tests/acp-integration.test.ts
+++ b/integration-tests/acp-integration.test.ts
@@ -311,9 +311,9 @@ function setupAcpTest(
     }
   });
 
-  it('returns modes on initialize and allows setting approval mode', async () => {
+  it('returns modes on initialize and allows setting mode and model', async () => {
     const rig = new TestRig();
-    rig.setup('acp approval mode');
+    rig.setup('acp mode and model');
 
     const { sendRequest, cleanup, stderr } = setupAcpTest(rig);
 
@@ -366,8 +366,14 @@ function setupAcpTest(
       const newSession = (await sendRequest('session/new', {
         cwd: rig.testDir!,
         mcpServers: [],
-      })) as { sessionId: string };
+      })) as {
+        sessionId: string;
+        models: {
+          availableModels: Array<{ modelId: string }>;
+        };
+      };
       expect(newSession.sessionId).toBeTruthy();
+      expect(newSession.models.availableModels.length).toBeGreaterThan(0);
 
       // Test 4: Set approval mode to 'yolo'
       const setModeResult = (await sendRequest('session/set_mode', {
@@ -392,6 +398,15 @@ function setupAcpTest(
       })) as { modeId: string };
       expect(setModeResult3).toBeDefined();
       expect(setModeResult3.modeId).toBe('default');
+
+      // Test 7: Set model using first available model
+      const firstModel = newSession.models.availableModels[0];
+      const setModelResult = (await sendRequest('session/set_model', {
+        sessionId: newSession.sessionId,
+        modelId: firstModel.modelId,
+      })) as { modelId: string };
+      expect(setModelResult).toBeDefined();
+      expect(setModelResult.modelId).toBeTruthy();
     } catch (e) {
       if (stderr.length) {
         console.error('Agent stderr:', stderr.join(''));
diff --git a/packages/cli/src/acp-integration/acp.ts b/packages/cli/src/acp-integration/acp.ts
index 82be72361..9c705c11e 100644
--- a/packages/cli/src/acp-integration/acp.ts
+++ b/packages/cli/src/acp-integration/acp.ts
@@ -70,6 +70,13 @@ export class AgentSideConnection implements Client {
           const validatedParams = schema.setModeRequestSchema.parse(params);
           return agent.setMode(validatedParams);
         }
+        case schema.AGENT_METHODS.session_set_model: {
+          if (!agent.setModel) {
+            throw RequestError.methodNotFound();
+          }
+          const validatedParams = schema.setModelRequestSchema.parse(params);
+          return agent.setModel(validatedParams);
+        }
         default:
           throw RequestError.methodNotFound(method);
       }
@@ -408,4 +415,5 @@ export interface Agent {
   prompt(params: schema.PromptRequest): Promise<schema.PromptResponse>;
   cancel(params: schema.CancelNotification): Promise<void>;
   setMode?(params: schema.SetModeRequest): Promise<schema.SetModeResponse>;
+  setModel?(params: schema.SetModelRequest): Promise<schema.SetModelResponse>;
 }
diff --git a/packages/cli/src/acp-integration/acpAgent.ts b/packages/cli/src/acp-integration/acpAgent.ts
index d56d196db..373bf67be 100644
--- a/packages/cli/src/acp-integration/acpAgent.ts
+++ b/packages/cli/src/acp-integration/acpAgent.ts
@@ -165,30 +165,11 @@ class GeminiAgent {
     this.setupFileSystem(config);
 
     const session = await this.createAndStoreSession(config);
-    const configuredModel = (
-      config.getModel() ||
-      this.config.getModel() ||
-      ''
-    ).trim();
-    const modelId = configuredModel || 'default';
-    const modelName = configuredModel || modelId;
+    const availableModels = this.buildAvailableModels(config);
 
     return {
       sessionId: session.getId(),
-      models: {
-        currentModelId: modelId,
-        availableModels: [
-          {
-            modelId,
-            name: modelName,
-            description: null,
-            _meta: {
-              contextLimit: tokenLimit(modelId),
-            },
-          },
-        ],
-        _meta: null,
-      },
+      models: availableModels,
     };
   }
 
@@ -305,15 +286,29 @@ class GeminiAgent {
   async setMode(params: acp.SetModeRequest): Promise<acp.SetModeResponse> {
     const session = this.sessions.get(params.sessionId);
     if (!session) {
-      throw new Error(`Session not found: ${params.sessionId}`);
+      throw acp.RequestError.invalidParams(
+        `Session not found for id: ${params.sessionId}`,
+      );
     }
     return session.setMode(params);
   }
 
+  async setModel(params: acp.SetModelRequest): Promise<acp.SetModelResponse> {
+    const session = this.sessions.get(params.sessionId);
+    if (!session) {
+      throw acp.RequestError.invalidParams(
+        `Session not found for id: ${params.sessionId}`,
+      );
+    }
+    return session.setModel(params);
+  }
+
   private async ensureAuthenticated(config: Config): Promise<void> {
     const selectedType = this.settings.merged.security?.auth?.selectedType;
     if (!selectedType) {
-      throw acp.RequestError.authRequired('No Selected Type');
+      throw acp.RequestError.authRequired(
+        'Use Qwen Code CLI to authenticate first.',
+      );
     }
 
     try {
@@ -382,4 +377,43 @@ class GeminiAgent {
 
     return session;
   }
+
+  private buildAvailableModels(
+    config: Config,
+  ): acp.NewSessionResponse['models'] {
+    const currentModelId = (
+      config.getModel() ||
+      this.config.getModel() ||
+      ''
+    ).trim();
+    const availableModels = config.getAvailableModels();
+
+    const mappedAvailableModels = availableModels.map((model) => ({
+      modelId: model.id,
+      name: model.label,
+      description: model.description ?? null,
+      _meta: {
+        contextLimit: tokenLimit(model.id),
+      },
+    }));
+
+    if (
+      currentModelId &&
+      !mappedAvailableModels.some((model) => model.modelId === currentModelId)
+    ) {
+      mappedAvailableModels.unshift({
+        modelId: currentModelId,
+        name: currentModelId,
+        description: null,
+        _meta: {
+          contextLimit: tokenLimit(currentModelId),
+        },
+      });
+    }
+
+    return {
+      currentModelId,
+      availableModels: mappedAvailableModels,
+    };
+  }
 }
diff --git a/packages/cli/src/acp-integration/schema.ts b/packages/cli/src/acp-integration/schema.ts
index 05b5b1908..4278f0dd4 100644
--- a/packages/cli/src/acp-integration/schema.ts
+++ b/packages/cli/src/acp-integration/schema.ts
@@ -15,6 +15,7 @@ export const AGENT_METHODS = {
   session_prompt: 'session/prompt',
   session_list: 'session/list',
   session_set_mode: 'session/set_mode',
+  session_set_model: 'session/set_model',
 };
 
 export const CLIENT_METHODS = {
@@ -266,6 +267,18 @@ export const modelInfoSchema = z.object({
   name: z.string(),
 });
 
+export const setModelRequestSchema = z.object({
+  sessionId: z.string(),
+  modelId: z.string(),
+});
+
+export const setModelResponseSchema = z.object({
+  modelId: z.string(),
+});
+
+export type SetModelRequest = z.infer<typeof setModelRequestSchema>;
+export type SetModelResponse = z.infer<typeof setModelResponseSchema>;
+
 export const sessionModelStateSchema = z.object({
   _meta: acpMetaSchema,
   availableModels: z.array(modelInfoSchema),
@@ -592,6 +605,7 @@ export const agentResponseSchema = z.union([
   promptResponseSchema,
   listSessionsResponseSchema,
   setModeResponseSchema,
+  setModelResponseSchema,
 ]);
 
 export const requestPermissionRequestSchema = z.object({
@@ -624,6 +638,7 @@ export const agentRequestSchema = z.union([
   promptRequestSchema,
   listSessionsRequestSchema,
   setModeRequestSchema,
+  setModelRequestSchema,
 ]);
 
 export const agentNotificationSchema = sessionNotificationSchema;
diff --git a/packages/cli/src/acp-integration/session/Session.test.ts b/packages/cli/src/acp-integration/session/Session.test.ts
new file mode 100644
index 000000000..af98fe25c
--- /dev/null
+++ b/packages/cli/src/acp-integration/session/Session.test.ts
@@ -0,0 +1,174 @@
+/**
+ * @license
+ * Copyright 2025 Qwen
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import { describe, it, expect, vi, beforeEach } from 'vitest';
+import { Session } from './Session.js';
+import type { Config, GeminiChat } from '@qwen-code/qwen-code-core';
+import { ApprovalMode } from '@qwen-code/qwen-code-core';
+import type * as acp from '../acp.js';
+import type { LoadedSettings } from '../../config/settings.js';
+import * as nonInteractiveCliCommands from '../../nonInteractiveCliCommands.js';
+
+vi.mock('../../nonInteractiveCliCommands.js', () => ({
+  getAvailableCommands: vi.fn(),
+  handleSlashCommand: vi.fn(),
+}));
+
+describe('Session', () => {
+  let mockChat: GeminiChat;
+  let mockConfig: Config;
+  let mockClient: acp.Client;
+  let mockSettings: LoadedSettings;
+  let session: Session;
+  let currentModel: string;
+  let setModelSpy: ReturnType<typeof vi.fn>;
+  let getAvailableCommandsSpy: ReturnType<typeof vi.fn>;
+
+  beforeEach(() => {
+    currentModel = 'qwen3-code-plus';
+    setModelSpy = vi.fn().mockImplementation(async (modelId: string) => {
+      currentModel = modelId;
+    });
+
+    mockChat = {
+      sendMessageStream: vi.fn(),
+      addHistory: vi.fn(),
+    } as unknown as GeminiChat;
+
+    mockConfig = {
+      setApprovalMode: vi.fn(),
+      setModel: setModelSpy,
+      getModel: vi.fn().mockImplementation(() => currentModel),
+    } as unknown as Config;
+
+    mockClient = {
+      sessionUpdate: vi.fn().mockResolvedValue(undefined),
+      requestPermission: vi.fn().mockResolvedValue({
+        outcome: { outcome: 'selected', optionId: 'proceed_once' },
+      }),
+      sendCustomNotification: vi.fn().mockResolvedValue(undefined),
+    } as unknown as acp.Client;
+
+    mockSettings = {
+      merged: {},
+    } as LoadedSettings;
+
+    getAvailableCommandsSpy = vi.mocked(nonInteractiveCliCommands)
+      .getAvailableCommands as unknown as ReturnType<typeof vi.fn>;
+    getAvailableCommandsSpy.mockResolvedValue([]);
+
+    session = new Session(
+      'test-session-id',
+      mockChat,
+      mockConfig,
+      mockClient,
+      mockSettings,
+    );
+  });
+
+  describe('setMode', () => {
+    it.each([
+      ['plan', ApprovalMode.PLAN],
+      ['default', ApprovalMode.DEFAULT],
+      ['auto-edit', ApprovalMode.AUTO_EDIT],
+      ['yolo', ApprovalMode.YOLO],
+    ] as const)('maps %s mode', async (modeId, expected) => {
+      const result = await session.setMode({
+        sessionId: 'test-session-id',
+        modeId,
+      });
+
+      expect(mockConfig.setApprovalMode).toHaveBeenCalledWith(expected);
+      expect(result).toEqual({ modeId });
+    });
+  });
+
+  describe('setModel', () => {
+    it('sets model via config and returns current model', async () => {
+      const result = await session.setModel({
+        sessionId: 'test-session-id',
+        modelId: '  qwen3-coder-plus  ',
+      });
+
+      expect(mockConfig.setModel).toHaveBeenCalledWith('qwen3-coder-plus', {
+        reason: 'user_request_acp',
+        context: 'session/set_model',
+      });
+      expect(mockConfig.getModel).toHaveBeenCalled();
+      expect(result).toEqual({ modelId: 'qwen3-coder-plus' });
+    });
+
+    it('rejects empty/whitespace model IDs', async () => {
+      await expect(
+        session.setModel({
+          sessionId: 'test-session-id',
+          modelId: '   ',
+        }),
+      ).rejects.toThrow('Invalid params');
+
+      expect(mockConfig.setModel).not.toHaveBeenCalled();
+    });
+
+    it('propagates errors from config.setModel', async () => {
+      const configError = new Error('Invalid model');
+      setModelSpy.mockRejectedValueOnce(configError);
+
+      await expect(
+        session.setModel({
+          sessionId: 'test-session-id',
+          modelId: 'invalid-model',
+        }),
+      ).rejects.toThrow('Invalid model');
+    });
+  });
+
+  describe('sendAvailableCommandsUpdate', () => {
+    it('sends available_commands_update from getAvailableCommands()', async () => {
+      getAvailableCommandsSpy.mockResolvedValueOnce([
+        {
+          name: 'init',
+          description: 'Initialize project context',
+        },
+      ]);
+
+      await session.sendAvailableCommandsUpdate();
+
+      expect(getAvailableCommandsSpy).toHaveBeenCalledWith(
+        mockConfig,
+        expect.any(AbortSignal),
+      );
+      expect(mockClient.sessionUpdate).toHaveBeenCalledWith({
+        sessionId: 'test-session-id',
+        update: {
+          sessionUpdate: 'available_commands_update',
+          availableCommands: [
+            {
+              name: 'init',
+              description: 'Initialize project context',
+              input: null,
+            },
+          ],
+        },
+      });
+    });
+
+    it('swallows errors and does not throw', async () => {
+      const consoleErrorSpy = vi
+        .spyOn(console, 'error')
+        .mockImplementation(() => undefined);
+      getAvailableCommandsSpy.mockRejectedValueOnce(
+        new Error('Command discovery failed'),
+      );
+
+      await expect(
+        session.sendAvailableCommandsUpdate(),
+      ).resolves.toBeUndefined();
+      expect(mockClient.sessionUpdate).not.toHaveBeenCalled();
+      expect(consoleErrorSpy).toHaveBeenCalled();
+      consoleErrorSpy.mockRestore();
+    });
+  });
+});
diff --git a/packages/cli/src/acp-integration/session/Session.ts b/packages/cli/src/acp-integration/session/Session.ts
index d83ba8a8d..5348d78df 100644
--- a/packages/cli/src/acp-integration/session/Session.ts
+++ b/packages/cli/src/acp-integration/session/Session.ts
@@ -52,6 +52,8 @@ import type {
   AvailableCommandsUpdate,
   SetModeRequest,
   SetModeResponse,
+  SetModelRequest,
+  SetModelResponse,
   ApprovalModeValue,
   CurrentModeUpdate,
 } from '../schema.js';
@@ -348,6 +350,31 @@ export class Session implements SessionContext {
     return { modeId: params.modeId };
   }
 
+  /**
+   * Sets the model for the current session.
+   * Validates the model ID and switches the model via Config.
+   */
+  async setModel(params: SetModelRequest): Promise<SetModelResponse> {
+    const modelId = params.modelId.trim();
+
+    if (!modelId) {
+      throw acp.RequestError.invalidParams('modelId cannot be empty');
+    }
+
+    // Attempt to set the model using config
+    await this.config.setModel(modelId, {
+      reason: 'user_request_acp',
+      context: 'session/set_model',
+    });
+
+    // Get updated model info
+    const currentModel = this.config.getModel();
+
+    return {
+      modelId: currentModel,
+    };
+  }
+
   /**
    * Sends a current_mode_update notification to the client.
    * Called after the agent switches modes (e.g., from exit_plan_mode tool).