Headless enhancement: add stream-json as input-format/output-format to support programmatically use (#926)

packages/cli/src/nonInteractive/io/JsonOutputAdapter.ts

@@ -0,0 +1,81 @@
+/**
+ * @license
+ * Copyright 2025 Qwen Team
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import type { Config } from '@qwen-code/qwen-code-core';
+import type { CLIAssistantMessage, CLIMessage } from '../types.js';
+import {
+  BaseJsonOutputAdapter,
+  type JsonOutputAdapterInterface,
+  type ResultOptions,
+} from './BaseJsonOutputAdapter.js';
+
+/**
+ * JSON output adapter that collects all messages and emits them
+ * as a single JSON array at the end of the turn.
+ * Supports both main agent and subagent messages through distinct APIs.
+ */
+export class JsonOutputAdapter
+  extends BaseJsonOutputAdapter
+  implements JsonOutputAdapterInterface
+{
+  private readonly messages: CLIMessage[] = [];
+
+  constructor(config: Config) {
+    super(config);
+  }
+
+  /**
+   * Emits message to the messages array (batch mode).
+   * Tracks the last assistant message for efficient result text extraction.
+   */
+  protected emitMessageImpl(message: CLIMessage): void {
+    this.messages.push(message);
+    // Track assistant messages for result generation
+    if (
+      typeof message === 'object' &&
+      message !== null &&
+      'type' in message &&
+      message.type === 'assistant'
+    ) {
+      this.updateLastAssistantMessage(message as CLIAssistantMessage);
+    }
+  }
+
+  /**
+   * JSON mode does not emit stream events.
+   */
+  protected shouldEmitStreamEvents(): boolean {
+    return false;
+  }
+
+  finalizeAssistantMessage(): CLIAssistantMessage {
+    const message = this.finalizeAssistantMessageInternal(
+      this.mainAgentMessageState,
+      null,
+    );
+    this.updateLastAssistantMessage(message);
+    return message;
+  }
+
+  emitResult(options: ResultOptions): void {
+    const resultMessage = this.buildResultMessage(
+      options,
+      this.lastAssistantMessage,
+    );
+    this.messages.push(resultMessage);
+
+    // Emit the entire messages array as JSON (includes all main agent + subagent messages)
+    const json = JSON.stringify(this.messages);
+    process.stdout.write(`${json}\n`);
+  }
+
+  emitMessage(message: CLIMessage): void {
+    // In JSON mode, messages are collected in the messages array
+    // This is called by the base class's finalizeAssistantMessageInternal
+    // but can also be called directly for user/tool/system messages
+    this.messages.push(message);
+  }
+}