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

packages/core/src/subagents/subagent-events.ts

@@ -9,6 +9,7 @@ import type {
   ToolCallConfirmationDetails,
   ToolConfirmationOutcome,
 } from '../tools/tools.js';
+import type { Part } from '@google/genai';
 
 export type SubAgentEvent =
   | 'start'
@@ -72,6 +73,7 @@ export interface SubAgentToolResultEvent {
   name: string;
   success: boolean;
   error?: string;
+  responseParts?: Part[];
   resultDisplay?: string;
   durationMs?: number;
   timestamp: number;

packages/core/src/subagents/subagent.ts

@@ -619,6 +619,13 @@ export class SubAgentScope {
             name: toolName,
             success,
             error: errorMessage,
+            responseParts: call.response.responseParts,
+            /**
+             * Tools like todoWrite will add some extra contents to the result,
+             * making it unable to deserialize the `responseParts` to a JSON object.
+             * While `resultDisplay` is normally a string, if not we stringify it,
+             * so that we can deserialize it to a JSON object when needed.
+             */
             resultDisplay: call.response.resultDisplay
               ? typeof call.response.resultDisplay === 'string'
                 ? call.response.resultDisplay