qwen-code/packages/cli/src/acp-integration/session/emitters/MessageEmitter.ts

/**
 * @license
 * Copyright 2025 Qwen
 * SPDX-License-Identifier: Apache-2.0
 */

import type { GenerateContentResponseUsageMetadata } from '@google/genai';
import type { Usage } from '../../schema.js';
import { BaseEmitter } from './BaseEmitter.js';

/**
 * Handles emission of text message chunks (user, agent, thought).
 *
 * This emitter is responsible for sending message content to the ACP client
 * in a consistent format, regardless of whether the message comes from
 * normal flow, history replay, or other sources.
 */
export class MessageEmitter extends BaseEmitter {
  /**
   * Emits a user message chunk.
   */
  async emitUserMessage(text: string): Promise<void> {
    await this.sendUpdate({
      sessionUpdate: 'user_message_chunk',
      content: { type: 'text', text },
    });
  }

  /**
   * Emits an agent thought chunk.
   */
  async emitAgentThought(text: string): Promise<void> {
    await this.sendUpdate({
      sessionUpdate: 'agent_thought_chunk',
      content: { type: 'text', text },
    });
  }

  /**
   * Emits an agent message chunk.
   */
  async emitAgentMessage(text: string): Promise<void> {
    await this.sendUpdate({
      sessionUpdate: 'agent_message_chunk',
      content: { type: 'text', text },
    });
  }

  /**
   * Emits usage metadata.
   */
  async emitUsageMetadata(
    usageMetadata: GenerateContentResponseUsageMetadata,
    text: string = '',
    durationMs?: number,
    subagentMeta?: import('../types.js').SubagentMeta,
  ): Promise<void> {
    const usage: Usage = {
      promptTokens: usageMetadata.promptTokenCount,
      completionTokens: usageMetadata.candidatesTokenCount,
      thoughtsTokens: usageMetadata.thoughtsTokenCount,
      totalTokens: usageMetadata.totalTokenCount,
      cachedTokens: usageMetadata.cachedContentTokenCount,
    };

    const meta =
      typeof durationMs === 'number'
        ? { usage, durationMs, ...subagentMeta }
        : { usage, ...subagentMeta };

    await this.sendUpdate({
      sessionUpdate: 'agent_message_chunk',
      content: { type: 'text', text },
      _meta: meta,
    });
  }

  /**
   * Emits a message chunk based on role and thought flag.
   * This is the unified method that handles all message types.
   *
   * @param text - The message text content
   * @param role - Whether this is a user or assistant message
   * @param isThought - Whether this is an assistant thought (only applies to assistant role)
   */
  async emitMessage(
    text: string,
    role: 'user' | 'assistant',
    isThought: boolean = false,
  ): Promise<void> {
    if (role === 'user') {
      return this.emitUserMessage(text);
    }
    return isThought
      ? this.emitAgentThought(text)
      : this.emitAgentMessage(text);
  }
}