Add /background commands (when background agent is configured) (#4407)

Co-authored-by: Bryan Morgan <bryanmorgan@google.com>

packages/cli/src/config/config.ts

@@ -382,6 +382,7 @@ export async function loadCliConfig(
     toolCallCommand: settings.toolCallCommand,
     mcpServerCommand: settings.mcpServerCommand,
     mcpServers,
+    backgroundAgents: settings.backgroundAgents,
     userMemory: memoryContent,
     geminiMdFileCount: fileCount,
     approvalMode: argv.yolo || false ? ApprovalMode.YOLO : ApprovalMode.DEFAULT,

packages/cli/src/config/settings.ts

@@ -64,6 +64,7 @@ export interface Settings {
   toolCallCommand?: string;
   mcpServerCommand?: string;
   mcpServers?: Record<string, MCPServerConfig>;
+  backgroundAgents?: Record<string, MCPServerConfig>;
   allowMCPServers?: string[];
   excludeMCPServers?: string[];
   showMemoryUsage?: boolean;

packages/cli/src/services/CommandService.test.ts

@@ -96,6 +96,7 @@ describe('CommandService', () => {
     mockConfig = {
       getIdeMode: vi.fn(),
       getCheckpointingEnabled: vi.fn(),
+      getBackgroundAgentManager: vi.fn(),
     } as unknown as Mocked<Config>;
     vi.mocked(ideCommand).mockReturnValue(null);
     vi.mocked(restoreCommand).mockReturnValue(null);

packages/cli/src/services/CommandService.ts

@@ -7,6 +7,7 @@
 import { Config } from '@google/gemini-cli-core';
 import { SlashCommand } from '../ui/commands/types.js';
 import { memoryCommand } from '../ui/commands/memoryCommand.js';
+import { backgroundCommand } from '../ui/commands/backgroundCommand.js';
 import { helpCommand } from '../ui/commands/helpCommand.js';
 import { clearCommand } from '../ui/commands/clearCommand.js';
 import { corgiCommand } from '../ui/commands/corgiCommand.js';
@@ -33,6 +34,7 @@ const loadBuiltInCommands = async (
   const allCommands = [
     aboutCommand,
     authCommand,
+    backgroundCommand(config),
     bugCommand,
     chatCommand,
     clearCommand,

packages/cli/src/ui/App.test.tsx

@@ -9,6 +9,7 @@ import { render } from 'ink-testing-library';
 import { AppWrapper as App } from './App.js';
 import {
   Config as ServerConfig,
+  BackgroundAgentManager,
   MCPServerConfig,
   ApprovalMode,
   ToolRegistry,
@@ -51,6 +52,7 @@ interface MockServerConfig {
   getSandbox: Mock<() => SandboxConfig | undefined>;
   getTargetDir: Mock<() => string>;
   getToolRegistry: Mock<() => ToolRegistry>; // Use imported ToolRegistry type
+  getBackgroundAgentManager: Mock<() => BackgroundAgentManager>;
   getDebugMode: Mock<() => boolean>;
   getQuestion: Mock<() => string | undefined>;
   getFullContext: Mock<() => boolean>;
@@ -117,6 +119,7 @@ vi.mock('@google/gemini-cli-core', async (importOriginal) => {
         getSandbox: vi.fn(() => opts.sandbox),
         getTargetDir: vi.fn(() => opts.targetDir || '/test/dir'),
         getToolRegistry: vi.fn(() => ({}) as ToolRegistry), // Simple mock
+        getBackgroundAgentManager: vi.fn(() => new BackgroundAgentManager([])),
         getDebugMode: vi.fn(() => opts.debugMode || false),
         getQuestion: vi.fn(() => opts.question),
         getFullContext: vi.fn(() => opts.fullContext ?? false),

packages/cli/src/ui/commands/backgroundCommand.ts

@@ -0,0 +1,262 @@
+/**
+ * @license
+ * Copyright 2025 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import { SlashCommand, CommandContext } from './types.js';
+import {
+  Config,
+  BackgroundAgentMessage,
+  partListUnionToString,
+} from '@google/gemini-cli-core';
+
+const MAX_STATUS_MESSAGE_LENGTH = 100;
+
+function toMessageString(message?: BackgroundAgentMessage): string {
+  return partListUnionToString(message?.parts ?? []).trim();
+}
+
+function toOneliner(input: string, maxlength: number) {
+  let output = input.replace(/\r?\n|\r/g, ' ');
+  if (output.length > maxlength) {
+    output = output.substring(0, maxlength) + '...';
+  }
+  return output;
+}
+
+function getActiveAgent(context: CommandContext) {
+  const agent =
+    context.services.config?.getBackgroundAgentManager()?.activeAgent;
+  if (!agent) {
+    throw Error('There is no active background agent.');
+  }
+  return agent;
+}
+
+function addClientHistory(context: CommandContext, text: string) {
+  context.services.config!.getGeminiClient().addHistory({
+    role: 'user',
+    parts: [{ text }],
+  });
+
+  context.services.config!.getGeminiClient().addHistory({
+    role: 'model',
+    parts: [{ text: 'Got it.' }],
+  });
+}
+
+const startSubcommand: SlashCommand = {
+  name: 'start',
+  description:
+    'Start a new task with the provided prompt. Usage: /bg start <prompt>',
+  action: async (context, args) => {
+    if (!args || args.trim() === '') {
+      return {
+        type: 'message',
+        messageType: 'error',
+        content: 'The `start` command requires a prompt.',
+      };
+    }
+
+    const agent = getActiveAgent(context);
+    const task = await agent.startTask(args);
+
+    addClientHistory(
+      context,
+      `I started a background task with id '${task.id}' and prompt:\n${args}`,
+    );
+
+    return {
+      type: 'message',
+      messageType: 'info',
+      content: `Started background task with id '${task.id}' and prompt:\n${args}`,
+    };
+  },
+};
+
+const stopSubcommand: SlashCommand = {
+  name: 'stop',
+  description: 'Stops a running task. Usage: /bg stop <task_id>',
+  action: async (context, args) => {
+    if (!args || args.trim() === '') {
+      return {
+        type: 'message',
+        messageType: 'error',
+        content: 'The `stop` command requires a task id.',
+      };
+    }
+    const agent = getActiveAgent(context);
+    await agent.cancelTask(args);
+    addClientHistory(context, `I canceled the background task with id ${args}`);
+    return {
+      type: 'message',
+      messageType: 'info',
+      content: `Stopped background task with id ${args}.`,
+    };
+  },
+};
+
+const listSubcommand: SlashCommand = {
+  name: 'list',
+  description: 'List all tasks',
+  action: async (context, args) => {
+    if (args && args.trim() !== '') {
+      return {
+        type: 'message',
+        messageType: 'error',
+        content: 'The `list` command takes no arguments.',
+      };
+    }
+
+    const agent = getActiveAgent(context);
+    const tasks = await agent.listTasks();
+    let content: string;
+    if (tasks.length === 0) {
+      content = 'No background tasks found.';
+    } else {
+      const taskList = tasks
+        .map((task) => {
+          const shortStatus = toOneliner(
+            toMessageString(task.status.message),
+            MAX_STATUS_MESSAGE_LENGTH,
+          );
+          return `  - ${task.id}: (${task.status.state}) ${shortStatus}`;
+        })
+        .join('\n');
+      content = `Background tasks:\n${taskList}`;
+    }
+    return {
+      type: 'message',
+      messageType: 'info',
+      content,
+    };
+  },
+};
+
+const getSubcommand: SlashCommand = {
+  name: 'get',
+  description: 'View a task. Usage: /bg get <task_id>',
+  action: async (context, args) => {
+    if (!args || args.trim() === '') {
+      return {
+        type: 'message',
+        messageType: 'error',
+        content: 'The `get` command requires a task id.',
+      };
+    }
+    const agent = getActiveAgent(context);
+    const task = await agent.getTask(args);
+    const content = `Task Details for ${task.id}:
+Status: (${task.status.state}) ${toMessageString(task.status.message)}}`;
+
+    return {
+      type: 'message',
+      messageType: 'info',
+      content,
+    };
+  },
+};
+
+const logsSubcommand: SlashCommand = {
+  name: 'logs',
+  description: "View a task's recent logs. Usage: /bg log <task_id>",
+  action: async (context, args) => {
+    if (!args || args.trim() === '') {
+      return {
+        type: 'message',
+        messageType: 'error',
+        content: 'The `log` command requires a task id.',
+      };
+    }
+    const agent = getActiveAgent(context);
+    const task = await agent.getTask(args, 5);
+    const contents = [
+      `Task logs for ${task.id}. status: (${task.status.state})`,
+    ];
+    (task.history ?? []).forEach((message) => {
+      contents.push(toMessageString(message));
+    });
+    return {
+      type: 'message',
+      messageType: 'info',
+      content: contents.join('\n\n'),
+    };
+  },
+};
+
+const messageSubcommand: SlashCommand = {
+  name: 'message',
+  description:
+    'Send a message to a task. Usage: /bg message <task_id> <message>',
+  action: async (context, args) => {
+    if (!args || args.trim() === '' || !args.trim().includes(' ')) {
+      return {
+        type: 'message',
+        messageType: 'error',
+        content: 'The `message` command requires a task id and a message.',
+      };
+    }
+
+    const firstSpaceIndex = args.indexOf(' ');
+    const id = args.substring(0, firstSpaceIndex);
+    const message = args.substring(firstSpaceIndex + 1);
+
+    const agent = getActiveAgent(context);
+    await agent.messageTask(id, message);
+    addClientHistory(
+      context,
+      `I sent a message to the background task with id '${id}':\n${message}`,
+    );
+
+    return {
+      type: 'message',
+      messageType: 'info',
+      content: `Sent a message to the background task with id '${id}':\n${message}`,
+    };
+  },
+};
+
+const deleteSubcommand: SlashCommand = {
+  name: 'delete',
+  description: 'Deletes a task. Usage: /bg delete <task_id>',
+  action: async (context, args) => {
+    if (!args) {
+      return {
+        type: 'message',
+        messageType: 'error',
+        content: 'The `delete` command requires a task id.',
+      };
+    }
+    const agent = getActiveAgent(context);
+    await agent.deleteTask(args);
+    addClientHistory(context, `I deleted the background task with id ${args}`);
+    return {
+      type: 'message',
+      messageType: 'info',
+      content: `Task ${args} deleted.`,
+    };
+  },
+};
+
+export const backgroundCommand = (
+  config: Config | null,
+): SlashCommand | null => {
+  if (!config?.getBackgroundAgentManager()?.activeAgent) {
+    return null;
+  }
+  return {
+    name: 'background',
+    altName: 'bg',
+    description: "Commands for managing the background agent's tasks",
+    subCommands: [
+      startSubcommand,
+      stopSubcommand,
+      listSubcommand,
+      getSubcommand,
+      logsSubcommand,
+      messageSubcommand,
+      deleteSubcommand,
+    ],
+  };
+};

packages/core/src/background/backgroundAgent.ts

@@ -0,0 +1,126 @@
+/**
+ * @license
+ * Copyright 2025 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import { MCPServerConfig } from '../config/config.js';
+import { connectToMcpServer, discoverTools } from '../tools/mcp-client.js';
+import { DiscoveredMCPTool } from '../tools/mcp-tool.js';
+import {
+  BackgroundAgentTasksResponseSchema,
+  BackgroundAgentTaskResponseSchema,
+  BackgroundAgentTask,
+} from './types.js';
+
+export async function loadBackgroundAgent(
+  name: string,
+  config: MCPServerConfig,
+  debugMode: boolean,
+): Promise<BackgroundAgent> {
+  const server = await connectToMcpServer(name, config, debugMode);
+  try {
+    const tools = await discoverTools(name, config, server);
+    return new BackgroundAgent(name, tools);
+  } catch (error) {
+    await server.close();
+    throw error;
+  }
+}
+
+export class BackgroundAgent {
+  readonly startTaskTool: DiscoveredMCPTool;
+  readonly getTaskTool: DiscoveredMCPTool;
+  readonly listTasksTool: DiscoveredMCPTool;
+  readonly messageTaskTool: DiscoveredMCPTool;
+  readonly deleteTaskTool: DiscoveredMCPTool;
+  readonly cancelTaskTool: DiscoveredMCPTool;
+
+  constructor(
+    readonly serverName: string,
+    tools: DiscoveredMCPTool[],
+  ) {
+    const getToolOrFail = (name: string): DiscoveredMCPTool => {
+      for (const tool of tools) {
+        if (tool.serverToolName === name) {
+          return tool;
+        }
+      }
+      throw new Error(`missing expected tool: ${name}`);
+    };
+
+    this.startTaskTool = getToolOrFail('startTask');
+    this.getTaskTool = getToolOrFail('getTask');
+    this.listTasksTool = getToolOrFail('listTasks');
+    this.messageTaskTool = getToolOrFail('messageTask');
+    this.deleteTaskTool = getToolOrFail('deleteTask');
+    this.cancelTaskTool = getToolOrFail('cancelTask');
+  }
+
+  async startTask(prompt: string): Promise<BackgroundAgentTask> {
+    const resp = await this.callTool(this.startTaskTool, {
+      prompt: {
+        role: 'user',
+        parts: [{ text: prompt }],
+      },
+    });
+    const taskResp = await BackgroundAgentTaskResponseSchema.parseAsync(resp);
+    return taskResp.structuredContent;
+  }
+
+  async getTask(
+    id: string,
+    historyLength?: number,
+  ): Promise<BackgroundAgentTask> {
+    const resp = await this.callTool(this.getTaskTool, {
+      id,
+      historyLength,
+    });
+    const taskResp = await BackgroundAgentTaskResponseSchema.parseAsync(resp);
+    return taskResp.structuredContent;
+  }
+
+  async listTasks(): Promise<BackgroundAgentTask[]> {
+    const resp = await this.callTool(this.listTasksTool, {});
+    const tasksResp = await BackgroundAgentTasksResponseSchema.parseAsync(resp);
+    return tasksResp.structuredContent;
+  }
+
+  async messageTask(id: string, message: string) {
+    await this.callTool(this.messageTaskTool, {
+      id,
+      message: {
+        role: 'user',
+        parts: [{ text: message }],
+      },
+    });
+  }
+
+  async deleteTask(id: string) {
+    await this.callTool(this.deleteTaskTool, { id });
+  }
+
+  async cancelTask(id: string) {
+    await this.callTool(this.cancelTaskTool, { id });
+  }
+
+  private async callTool(
+    tool: DiscoveredMCPTool,
+    params: Record<string, unknown>,
+  ): Promise<Record<string, unknown>> {
+    const { llmContent: parts } = await tool.execute(params);
+    if (
+      !Array.isArray(parts) ||
+      parts.length !== 1 ||
+      typeof parts[0] !== 'object' ||
+      parts[0]?.functionResponse?.response === undefined
+    ) {
+      throw new Error('Expected exactly one part with a functionResponse');
+    }
+    const resp = parts[0].functionResponse.response;
+    if ('isError' in resp && resp.isError) {
+      throw new Error(`Error calling ${tool.displayName}: ${resp}`);
+    }
+    return resp;
+  }
+}

packages/core/src/background/backgroundManager.ts

@@ -0,0 +1,40 @@
+/**
+ * @license
+ * Copyright 2025 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import { MCPServerConfig } from '../config/config.js';
+import { BackgroundAgent, loadBackgroundAgent } from './backgroundAgent.js';
+
+export async function loadBackgroundAgentManager(
+  backgroundAgentConfigs: Record<string, MCPServerConfig> | undefined,
+  debugMode: boolean,
+): Promise<BackgroundAgentManager> {
+  const agents = await Promise.all(
+    Object.entries(backgroundAgentConfigs ?? {}).map(([name, config]) =>
+      loadBackgroundAgent(name, config, debugMode).catch((error) => {
+        console.error(`Error loading background agent '${name}': ${error}`);
+        return null;
+      }),
+    ),
+  ).then((agents) => agents.filter((agent) => agent !== null));
+  return new BackgroundAgentManager(agents);
+}
+
+export class BackgroundAgentManager {
+  // The active agent. May be empty if none are confgured.
+  activeAgent?: BackgroundAgent;
+
+  constructor(readonly backgroundAgents: BackgroundAgent[]) {
+    if (backgroundAgents.length !== 0) {
+      this.activeAgent = backgroundAgents[0];
+    }
+  }
+
+  setActiveAgentByName(name: string) {
+    this.activeAgent = this.backgroundAgents.find(
+      (agent) => agent.serverName === name,
+    );
+  }
+}

packages/core/src/background/types.ts

@@ -0,0 +1,107 @@
+/**
+ * @license
+ * Copyright 2025 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import { z } from 'zod';
+import { Outcome, Language, FunctionResponseScheduling } from '@google/genai';
+
+// Should conform to Part in @google/genai
+export const PartSchema = z.object({
+  videoMetadata: z
+    .object({
+      fps: z.number().optional(),
+      endOffset: z.string().optional(),
+      startOffset: z.string().optional(),
+    })
+    .optional(),
+  thought: z.boolean().optional(),
+  inlineData: z
+    .object({
+      displayName: z.string().optional(),
+      data: z.string(),
+      mimeType: z.string(),
+    })
+    .optional(),
+  fileData: z
+    .object({
+      displayName: z.string().optional(),
+      fileUri: z.string(),
+      mimeType: z.string(),
+    })
+    .optional(),
+  thoughtSignature: z.string().optional(),
+  codeExecutionResult: z
+    .object({
+      outcome: z.nativeEnum(Outcome).optional(),
+      output: z.string().optional(),
+    })
+    .optional(),
+  executableCode: z
+    .object({
+      code: z.string().optional(),
+      language: z.nativeEnum(Language).optional(),
+    })
+    .optional(),
+  functionCall: z
+    .object({
+      id: z.string().optional(),
+      args: z.record(z.unknown()).optional(),
+      name: z.string(),
+    })
+    .optional(),
+  functionResponse: z
+    .object({
+      willContinue: z.boolean().optional(),
+      scheduling: z.nativeEnum(FunctionResponseScheduling).optional(),
+      id: z.string().optional(),
+      name: z.string(),
+      response: z.record(z.unknown()).optional(),
+    })
+    .optional(),
+  text: z.string().optional(),
+});
+
+export const BackgroundAgentMessageSchema = z.object({
+  role: z.enum(['user', 'agent']).describe('The role of the sender.'),
+  parts: z.array(PartSchema).describe('The parts of the message.'),
+});
+
+export const BackgroundAgentTaskStatusSchema = z.object({
+  state: z.enum([
+    'submitted',
+    'working',
+    'input-required',
+    'completed',
+    'failed',
+  ]),
+  message: BackgroundAgentMessageSchema.describe(
+    'Message describing the state of the task.',
+  ).optional(),
+});
+
+export const BackgroundAgentTaskSchema = z.object({
+  id: z.string().describe('The id of the task. Must match `[a-zA-Z0-9.-_]+`'),
+  status: BackgroundAgentTaskStatusSchema.describe(
+    'The current status of the task.',
+  ),
+  history: z
+    .array(BackgroundAgentMessageSchema)
+    .describe('Recent history of messages associated with this task')
+    .optional(),
+});
+
+export type BackgroundAgentMessage = z.infer<
+  typeof BackgroundAgentMessageSchema
+>;
+
+export type BackgroundAgentTask = z.infer<typeof BackgroundAgentTaskSchema>;
+
+export const BackgroundAgentTaskResponseSchema = z.object({
+  structuredContent: BackgroundAgentTaskSchema,
+});
+
+export const BackgroundAgentTasksResponseSchema = z.object({
+  structuredContent: z.array(BackgroundAgentTaskSchema),
+});

packages/core/src/config/config.ts

@@ -45,6 +45,10 @@ import {
   DEFAULT_GEMINI_FLASH_MODEL,
 } from './models.js';
 import { ClearcutLogger } from '../telemetry/clearcut-logger/clearcut-logger.js';
+import {
+  BackgroundAgentManager,
+  loadBackgroundAgentManager,
+} from '../background/backgroundManager.js';
 
 export enum ApprovalMode {
   DEFAULT = 'default',
@@ -127,6 +131,7 @@ export interface ConfigParameters {
   toolCallCommand?: string;
   mcpServerCommand?: string;
   mcpServers?: Record<string, MCPServerConfig>;
+  backgroundAgents?: Record<string, MCPServerConfig>;
   userMemory?: string;
   geminiMdFileCount?: number;
   approvalMode?: ApprovalMode;
@@ -158,6 +163,7 @@ export interface ConfigParameters {
 
 export class Config {
   private toolRegistry!: ToolRegistry;
+  private backgroundAgentManager?: BackgroundAgentManager;
   private readonly sessionId: string;
   private contentGeneratorConfig!: ContentGeneratorConfig;
   private readonly embeddingModel: string;
@@ -172,6 +178,7 @@ export class Config {
   private readonly toolCallCommand: string | undefined;
   private readonly mcpServerCommand: string | undefined;
   private readonly mcpServers: Record<string, MCPServerConfig> | undefined;
+  private readonly backgroundAgents?: Record<string, MCPServerConfig>;
   private userMemory: string;
   private geminiMdFileCount: number;
   private approvalMode: ApprovalMode;
@@ -224,6 +231,7 @@ export class Config {
     this.toolCallCommand = params.toolCallCommand;
     this.mcpServerCommand = params.mcpServerCommand;
     this.mcpServers = params.mcpServers;
+    this.backgroundAgents = params.backgroundAgents;
     this.userMemory = params.userMemory ?? '';
     this.geminiMdFileCount = params.geminiMdFileCount ?? 0;
     this.approvalMode = params.approvalMode ?? ApprovalMode.DEFAULT;
@@ -281,6 +289,10 @@ export class Config {
     if (this.getCheckpointingEnabled()) {
       await this.getGitService();
     }
+    this.backgroundAgentManager = await loadBackgroundAgentManager(
+      this.backgroundAgents,
+      this.debugMode,
+    );
     this.toolRegistry = await this.createToolRegistry();
   }
 
@@ -406,6 +418,10 @@ export class Config {
     return this.mcpServers;
   }
 
+  getBackgroundAgentManager(): BackgroundAgentManager | undefined {
+    return this.backgroundAgentManager;
+  }
+
   getUserMemory(): string {
     return this.userMemory;
   }

packages/core/src/index.ts

@@ -24,6 +24,9 @@ export * from './code_assist/oauth2.js';
 export * from './code_assist/server.js';
 export * from './code_assist/types.js';
 
+export * from './background/types.js';
+export * from './background/backgroundManager.js';
+
 // Export utilities
 export * from './utils/paths.js';
 export * from './utils/schemaValidator.js';

packages/core/src/tools/mcp-tool.ts

@@ -113,9 +113,7 @@ export class DiscoveredMCPTool extends BaseTool<ToolParams, ToolResult> {
         args: params,
       },
     ];
-
+    const responseParts = await this.mcpTool.callTool(functionCalls);
-    const responseParts: Part[] = await this.mcpTool.callTool(functionCalls);
-
     return {
       llmContent: responseParts,
       returnDisplay: getStringifiedResultForDisplay(responseParts),