feat: Implement subagents phase 1 with file-based configuration system

Co-authored-by: Qwen-Coder <qwen-coder@alibabacloud.com>

packages/core/src/subagents/index.ts

@@ -0,0 +1,53 @@
+/**
+ * @license
+ * Copyright 2025 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+/**
+ * @fileoverview Subagents Phase 1 implementation - File-based configuration layer
+ *
+ * This module provides the foundation for the subagents feature by implementing
+ * a file-based configuration system that builds on the existing SubAgentScope
+ * runtime system. It includes:
+ *
+ * - Type definitions for file-based subagent configurations
+ * - Validation system for configuration integrity
+ * - Runtime conversion functions integrated into the manager
+ * - Manager class for CRUD operations on subagent files
+ *
+ * The implementation follows the Markdown + YAML frontmatter format specified
+ * in the Claude Code product manual, with storage at both project and user levels.
+ */
+
+// Core types and interfaces
+export type {
+  SubagentConfig,
+  SubagentMetadata,
+  SubagentLevel,
+  SubagentRuntimeConfig,
+  ValidationResult,
+  ListSubagentsOptions,
+  CreateSubagentOptions,
+  SubagentErrorCode,
+} from './types.js';
+
+export { SubagentError } from './types.js';
+
+// Validation system
+export { SubagentValidator } from './validation.js';
+
+// Main management class
+export { SubagentManager } from './subagent-manager.js';
+
+// Re-export existing runtime types for convenience
+export type {
+  PromptConfig,
+  ModelConfig,
+  RunConfig,
+  ToolConfig,
+  SubagentTerminateMode,
+  OutputObject,
+} from '../core/subagent.js';
+
+export { SubAgentScope } from '../core/subagent.js';