Agent-Native/runtime/subagent/subagent.go

// Package subagent 定义委派端口：内核不内置嵌套执行（那是编排层职责），
// 只提供工具面与信息集契约；宿主（产品 SpawnSubagent、小队引擎等）
// 注入 Factory 实现真实派生执行。未注入则 delegate_task 不注册（fail-closed）。
//
// 信息集对齐 agent-execution 标准的委派条款：目标、输入、写范围、非目标、
// 完成判据、预算与回传格式——子任务不能从父任务目标推导额外权限。
package subagent

import (
	"context"
	"encoding/json"
	"fmt"
	"sort"
	"strings"
	"time"
	"unicode/utf8"

	"agent-native/runtime/tools"
)

// Request 是一次委派的完整信息集（模型经工具参数逐项填写）。
type Request struct {
	Goal         string   `json:"goal"`
	Inputs       string   `json:"inputs,omitempty"`
	WriteScope   string   `json:"write_scope,omitempty"`
	NonGoals     string   `json:"non_goals,omitempty"`
	DoneCriteria string   `json:"done_criteria,omitempty"`
	Deliverables []string `json:"deliverables,omitempty"`
	// Deadline / MaxToolCalls 是宿主注入的预算余量（模型不可自行扩权）。
	Deadline     time.Time `json:"-"`
	MaxToolCalls int       `json:"-"`
}

// Result 是子代理的回传：至少包含结论文本；文件由宿主按写范围物化。
type Result struct {
	Success bool
	Text    string
	Files   map[string][]byte
	Err     string
}

// Factory 由宿主注入；ctx 取消必须传播到子执行。
type Factory func(ctx context.Context, req Request) (Result, error)

type delegateTool struct{ factory Factory }

// Register 把 delegate_task 工具注册进注册表（factory 为 nil 时不注册）。
func Register(r *tools.Registry, factory Factory) {
	if factory == nil {
		return
	}
	r.Register(&delegateTool{factory: factory})
}

func (t *delegateTool) Name() string { return "delegate_task" }
func (t *delegateTool) Description() string {
	return "Delegate a self-contained subtask to a fresh sub-agent. Fill every field: goal, inputs (with versions), write_scope (directory the sub-agent may write), non_goals, done_criteria, deliverables. The sub-agent cannot exceed your permissions; report back its conclusion and files."
}
func (t *delegateTool) Parameters() json.RawMessage {
	return json.RawMessage(`{"type":"object","required":["goal","done_criteria"],"properties":{
		"goal":{"type":"string"},
		"inputs":{"type":"string"},
		"write_scope":{"type":"string"},
		"non_goals":{"type":"string"},
		"done_criteria":{"type":"string"},
		"deliverables":{"type":"array","items":{"type":"string"}}
	}}`)
}

func (t *delegateTool) Execute(ctx context.Context, args json.RawMessage) (tools.Result, error) {
	var req Request
	if err := json.Unmarshal(args, &req); err != nil {
		return tools.Result{}, err
	}
	if strings.TrimSpace(req.Goal) == "" {
		return tools.Result{Content: "goal is empty", IsError: true}, nil
	}
	if ctx.Err() != nil {
		return tools.Result{Content: "delegation canceled before start: " + ctx.Err().Error(), IsError: true}, nil
	}
	res, err := t.factory(ctx, req)
	if err != nil {
		return tools.Result{Content: fmt.Sprintf("sub-agent failed: %v", err), IsError: true}, nil
	}
	shown, full := CapParentText(res.Text)
	if full != nil {
		if res.Files == nil {
			res.Files = map[string][]byte{}
		}
		res.Files["subagent-result.txt"] = full
		shown += "\n完整结果见 subagent-result.txt"
	}
	res.Text = shown
	var b strings.Builder
	if res.Success {
		b.WriteString("[sub-agent succeeded]\n")
	} else {
		b.WriteString("[sub-agent failed]\n")
	}
	if res.Err != "" {
		b.WriteString("error: " + res.Err + "\n")
	}
	b.WriteString(res.Text)
	if len(res.Files) > 0 {
		names := make([]string, 0, len(res.Files))
		for name := range res.Files {
			names = append(names, name)
		}
		sort.Strings(names)
		b.WriteString("\nfiles: " + strings.Join(names, ", "))
	}
	return tools.Result{Content: b.String(), IsError: !res.Success}, nil
}

// ParentResultCap 是回传父会话的默认字符上限。
const ParentResultCap = 32000

// CapParentText 超出上限时返回截断文本和全文，由调用方把全文写成工件或文件。
func CapParentText(text string) (shown string, full []byte) {
	if utf8.RuneCountInString(text) <= ParentResultCap {
		return text, nil
	}
	return string([]rune(text)[:ParentResultCap]), []byte(text)
}