第七章 Task System (任务系统)
s01 > s02 > s03 > s04 > s05 > s06 | [ s07 ] s08 > s09 > s10 > s11 > s12
“本专栏基于开源项目
learn-claude-code的官方文档。原文档非常硬核，为了方便像我一样的新手小白理解，我对文档进行了逐行精读，并加入了很多中文注释、大白话解释和踩坑记录。希望这套‘咀嚼版’教程能帮你推开 AI Agent 开发的大门。”
"大目标要拆成小任务, 排好序, 记在磁盘上" -- 文件持久化的任务图, 为多 agent 协作打基础。
一、问题-上下文耦合困境
s03 的 TodoManager 只是内存中的扁平清单: 没有顺序、没有依赖、状态只有做完没做完，进程结束就没了。真实目标是有结构的 -- 任务 B 依赖任务 A, 任务 C 和 D 可以并行, 任务 E 要等 C 和 D 都完成。
没有显式的关系, 智能体分不清什么能做、什么被卡住、什么能同时跑。而且清单只活在内存里, 上下文压缩 (s06) 一跑就没了。
二、解决方案
把扁平清单升级为持久化到磁盘的任务图。每个任务是一个 JSON 文件, 有状态、前置依赖 (blockedBy) 和后置依赖 (blocks)。任务图随时回答三个问题:
- 什么可以做? -- 状态为
pending且blockedBy为空的任务。 - 什么被卡住? -- 等待前置任务完成的任务。
- 什么做完了? -- 状态为
completed的任务, 完成时自动解锁后续任务。
.tasks/
task_1.json {"id":1, "status":"completed"}
task_2.json {"id":2, "blockedBy":[1], "status":"pending"}
task_3.json {"id":3, "blockedBy":[1], "status":"pending"}
task_4.json {"id":4, "blockedBy":[2,3], "status":"pending"}
任务图 (DAG):
+----------+
+--> | task 2 | --+
| | pending | |
+----------+ +----------+ +--> +----------+
| task 1 | | task 4 |
| completed| --> +----------+ +--> | blocked |
+----------+ | task 3 | --+ +----------+
| pending |
+----------+
顺序: task 1 必须先完成, 才能开始 2 和 3
并行: task 2 和 3 可以同时执行
依赖: task 4 要等 2 和 3 都完成
状态: pending -> in_progress -> completed
这个任务图是 s07 之后所有机制的协调骨架: 后台执行 (s08)、多 agent 团队 (s09+)、worktree 隔离 (s12) 都读写这同一个结构。
三、工作原理
- TaskManager: 每个任务一个 JSON 文件, CRUD + 依赖图。每个任务有 blockedBy（前置依赖）和 blocks（后置依赖）
class TaskManager:
def __init__(self, tasks_dir: Path):
self.dir = tasks_dir
self.dir.mkdir(exist_ok=True) # 创建.tasks/ 目录
self._next_id = self._max_id() + 1 # 找出当前已存在的最大任务ID然后加一
def _save(self, task: dict):
path = self.dir / f"task_{task['id']}.json"
path.write_text(json.dumps(task, indent=2))
def create(self, subject, description=""):
task = {
"id": self._next_id,
"subject": subject,
"status": "pending",
"blockedBy": [], # 前置依赖
"blocks": [], # 后置依赖
"owner": ""
}
self._save(task)
self._next_id += 1
return json.dumps(task, indent=2)
- 依赖解除: 完成任务时, 自动将其 ID 从其他任务的
blockedBy中移除, 解锁后续任务。
def _clear_dependency(self, completed_id):
for f in self.dir.glob("task_*.json"):
task = json.loads(f.read_text())
if completed_id in task.get("blockedBy", []):
task["blockedBy"].remove(completed_id)
self._save(task)
- 状态变更 + 依赖关联:
update处理状态转换和依赖边。
def update(self, task_id, status=None,
add_blocked_by=None, add_blocks=None):
......
# s07: update 方法中维护双向依赖
if add_blocks:
task["blocks"] = list(set(task["blocks"] + add_blocks))
# 同时更新被阻塞任务的 blockedBy 列表
for blocked_id in add_blocks:
try:
blocked = self._load(blocked_id)
if task_id not in blocked["blockedBy"]:
blocked["blockedBy"].append(task_id)
self._save(blocked)
except ValueError:
pass
三种状态的流转：pending（待处理） → in_progress（进行中） → completed（已完成）。当任务变为 completed 时，会自动触发 _clear_dependency() 方法，将该任务 ID 从其他所有任务的 blockedBy 列表中移除，从而解锁后续任务。
- 四个任务工具加入 dispatch map。
TOOL_HANDLERS = {
# ...base tools...
"task_create": lambda **kw: TASKS.create(kw["subject"]),
"task_update": lambda **kw: TASKS.update(kw["task_id"], kw.get("status")),
"task_list": lambda **kw: TASKS.list_all(),
"task_get": lambda **kw: TASKS.get(kw["task_id"]),
}
从 s07 起, 任务图是多步工作的默认选择。s03 的 Todo 仍可用于单次会话内的快速清单。
| 工具 | 作用 |
|---|---|
| task_create | 创建新任务，指定主题和描述，初始状态为 pending |
| task_update | 更新任务状态（pending/in_progress/completed）或依赖关系 |
| task_list | 列出所有任务及其状态，显示哪些任务被阻塞 |
| task_get | 获取单个任务的完整详细信息 |
四、相对 s06 的变更
| 组件 | 之前 (s06) | 之后 (s07) |
|---|---|---|
| Tools | 5 | 8 (task_create/update/list/get) |
| 规划模型 | 扁平清单 (仅内存) | 带依赖关系的任务图 (磁盘) |
| 关系 | 无 | blockedBy + blocks 边 |
| 状态追踪 | 做完没做完 | pending -> in_progress -> completed |
| 持久化 | 压缩后丢失 | 压缩和重启后存活 |
五、试一试
cd learn-claude-code
python agents/s07_task_system.py
试试这些 prompt (英文 prompt 对 LLM 效果更好, 也可以用中文):
Create 3 tasks: "Setup project", "Write code", "Write tests". Make them depend on each other in order.List all tasks and show the dependency graphComplete task 1 and then list tasks to see task 2 unblockedCreate a task board for refactoring: parse -> transform -> emit -> test, where transform and emit can run in parallel after parse
六、完整代码
#!/usr/bin/env python3
import json
import os
import subprocess
from pathlib import Path
from anthropic import Anthropic
from dotenv import load_dotenv
load_dotenv(override=True)
if os.getenv("ANTHROPIC_BASE_URL"):
os.environ.pop("ANTHROPIC_AUTH_TOKEN", None)
WORKDIR = Path.cwd()
client = Anthropic(base_url=os.getenv("ANTHROPIC_BASE_URL"))
MODEL = os.environ["MODEL_ID"]
TASKS_DIR = WORKDIR / ".tasks"
SYSTEM = f"You are a coding agent at {WORKDIR}. Use task tools to plan and track work."
# -- TaskManager: CRUD with dependency graph, persisted as JSON files --
class TaskManager:
def __init__(self, tasks_dir: Path):
self.dir = tasks_dir
self.dir.mkdir(exist_ok=True)
self._next_id = self._max_id() + 1
def _max_id(self) -> int:
ids = [int(f.stem.split("_")[1]) for f in self.dir.glob("task_*.json")]
return max(ids) if ids else 0
def _load(self, task_id: int) -> dict:
path = self.dir / f"task_{task_id}.json"
if not path.exists():
raise ValueError(f"Task {task_id} not found")
return json.loads(path.read_text())
def _save(self, task: dict):
path = self.dir / f"task_{task['id']}.json"
path.write_text(json.dumps(task, indent=2))
def create(self, subject: str, description: str = "") -> str:
task = {
"id": self._next_id, "subject": subject, "description": description,
"status": "pending", "blockedBy": [], "blocks": [], "owner": "",
}
self._save(task)
self._next_id += 1
return json.dumps(task, indent=2)
def get(self, task_id: int) -> str:
return json.dumps(self._load(task_id), indent=2)
def update(self, task_id: int, status: str = None,
add_blocked_by: list = None, add_blocks: list = None) -> str:
task = self._load(task_id)
if status:
if status not in ("pending", "in_progress", "completed"):
raise ValueError(f"Invalid status: {status}")
task["status"] = status
# When a task is completed, remove it from all other tasks' blockedBy
if status == "completed":
self._clear_dependency(task_id)
if add_blocked_by:
task["blockedBy"] = list(set(task["blockedBy"] + add_blocked_by))
if add_blocks:
task["blocks"] = list(set(task["blocks"] + add_blocks))
# Bidirectional: also update the blocked tasks' blockedBy lists
for blocked_id in add_blocks:
try:
blocked = self._load(blocked_id)
if task_id not in blocked["blockedBy"]:
blocked["blockedBy"].append(task_id)
self._save(blocked)
except ValueError:
pass
self._save(task)
return json.dumps(task, indent=2)
def _clear_dependency(self, completed_id: int):
"""Remove completed_id from all other tasks' blockedBy lists."""
for f in self.dir.glob("task_*.json"):
task = json.loads(f.read_text())
if completed_id in task.get("blockedBy", []):
task["blockedBy"].remove(completed_id)
self._save(task)
def list_all(self) -> str:
tasks = []
for f in sorted(self.dir.glob("task_*.json")):
tasks.append(json.loads(f.read_text()))
if not tasks:
return "No tasks."
lines = []
for t in tasks:
marker = {
"pending": "[ ]", "in_progress": "[>]", "completed": "[x]"}.get(t["status"], "[?]")
blocked = f" (blocked by: {t['blockedBy']})" if t.get("blockedBy") else ""
lines.append(f"{marker} #{t['id']}: {t['subject']}{blocked}")
return "\n".join(lines)
TASKS = TaskManager(TASKS_DIR)
# -- Base tool implementations --
def safe_path(p: str) -> Path:
path = (WORKDIR / p).resolve()
if not path.is_relative_to(WORKDIR):
raise ValueError(f"Path escapes workspace: {p}")
return path
def run_bash(command: str) -> str:
dangerous = ["rm -rf /", "sudo", "shutdown", "reboot", "> /dev/"]
if any(d in command for d in dangerous):
return "Error: Dangerous command blocked"
try:
r = subprocess.run(command, shell=True, cwd=WORKDIR,
capture_output=True, text=True, timeout=120)
out = (r.stdout + r.stderr).strip()
return out[:50000] if out else "(no output)"
except subprocess.TimeoutExpired:
return "Error: Timeout (120s)"
def run_read(path: str, limit: int = None) -> str:
try:
lines = safe_path(path).read_text().splitlines()
if limit and limit < len(lines):
lines = lines[:limit] + [f"... ({len(lines) - limit} more)"]
return "\n".join(lines)[:50000]
except Exception as e:
return f"Error: {e}"
def run_write(path: str, content: str) -> str:
try:
fp = safe_path(path)
fp.parent.mkdir(parents=True, exist_ok=True)
fp.write_text(content)
return f"Wrote {len(content)} bytes"
except Exception as e:
return f"Error: {e}"
def run_edit(path: str, old_text: str, new_text: str) -> str:
try:
fp = safe_path(path)
c = fp.read_text()
if old_text not in c:
return f"Error: Text not found in {path}"
fp.write_text(c.replace(old_text, new_text, 1))
return f"Edited {path}"
except Exception as e:
return f"Error: {e}"
TOOL_HANDLERS = {
"bash": lambda **kw: run_bash(kw["command"]),
"read_file": lambda **kw: run_read(kw["path"], kw.get("limit")),
"write_file": lambda **kw: run_write(kw["path"], kw["content"]),
"edit_file": lambda **kw: run_edit(kw["path"], kw["old_text"], kw["new_text"]),
"task_create": lambda **kw: TASKS.create(kw["subject"], kw.get("description", "")),
"task_update": lambda **kw: TASKS.update(kw["task_id"], kw.get("status"), kw.get("addBlockedBy"), kw.get("addBlocks")),
"task_list": lambda **kw: TASKS.list_all(),
"task_get": lambda **kw: TASKS.get(kw["task_id"]),
}
TOOLS = [
{
"name": "bash", "description": "Run a shell command.",
"input_schema": {
"type": "object", "properties": {
"command": {
"type": "string"}}, "required": ["command"]}},
{
"name": "read_file", "description": "Read file contents.",
"input_schema": {
"type": "object", "properties": {
"path": {
"type": "string"}, "limit": {
"type": "integer"}}, "required": ["path"]}},
{
"name": "write_file", "description": "Write content to file.",
"input_schema": {
"type": "object", "properties": {
"path": {
"type": "string"}, "content": {
"type": "string"}}, "required": ["path", "content"]}},
{
"name": "edit_file", "description": "Replace exact text in file.",
"input_schema": {
"type": "object", "properties": {
"path": {
"type": "string"}, "old_text": {
"type": "string"}, "new_text": {
"type": "string"}}, "required": ["path", "old_text", "new_text"]}},
{
"name": "task_create", "description": "Create a new task.",
"input_schema": {
"type": "object", "properties": {
"subject": {
"type": "string"}, "description": {
"type": "string"}}, "required": ["subject"]}},
{
"name": "task_update", "description": "Update a task's status or dependencies.",
"input_schema": {
"type": "object", "properties": {
"task_id": {
"type": "integer"}, "status": {
"type": "string", "enum": ["pending", "in_progress", "completed"]}, "addBlockedBy": {
"type": "array", "items": {
"type": "integer"}}, "addBlocks": {
"type": "array", "items": {
"type": "integer"}}}, "required": ["task_id"]}},
{
"name": "task_list", "description": "List all tasks with status summary.",
"input_schema": {
"type": "object", "properties": {
}}},
{
"name": "task_get", "description": "Get full details of a task by ID.",
"input_schema": {
"type": "object", "properties": {
"task_id": {
"type": "integer"}}, "required": ["task_id"]}},
]
def agent_loop(messages: list):
while True:
response = client.messages.create(
model=MODEL, system=SYSTEM, messages=messages,
tools=TOOLS, max_tokens=8000,
)
messages.append({
"role": "assistant", "content": response.content})
if response.stop_reason != "tool_use":
return
results = []
for block in response.content:
if block.type == "tool_use":
handler = TOOL_HANDLERS.get(block.name)
try:
output = handler(**block.input) if handler else f"Unknown tool: {block.name}"
except Exception as e:
output = f"Error: {e}"
print(f"> {block.name}: {str(output)[:200]}")
results.append({
"type": "tool_result", "tool_use_id": block.id, "content": str(output)})
messages.append({
"role": "user", "content": results})
if __name__ == "__main__":
history = []
while True:
try:
query = input("\033[36ms07 >> \033[0m")
except (EOFError, KeyboardInterrupt):
break
if query.strip().lower() in ("q", "exit", ""):
break
history.append({
"role": "user", "content": query})
agent_loop(history)
response_content = history[-1]["content"]
if isinstance(response_content, list):
for block in response_content:
if hasattr(block, "text"):
print(block.text)
print()
