code/agent.py

"""agent.py — 极简工具调用 Agent，用于测试小模型（MiniCPM5-2B 等）的 function calling

为什么需要它：Claude Code / ZCode 这类 agent 的系统提示动辄上万 token，
超过本地小模型的上下文包线（本机 6GB 卡：bf16 ~3K / fp16 ~8K token）。
本 agent 的固定开销控制在 ~150 token 以内。

用法：
  .venv/bin/python agent.py                     # 交互式终端界面（REPL）
  .venv/bin/python agent.py "创建 /tmp/agent_test.txt 写入 hello，然后读回确认"   # 单轮模式
  .venv/bin/python agent.py --url http://127.0.0.1:8000/v1 --thinking off "列出当前目录文件"

交互界面命令：
  /quit  /exit     退出
  /reset           清空会话历史
  /yes             切换 shell 命令逐条确认开关
  /ablate off|on [k]  本次会话的请求级消融开关与子空间维度（默认跟随服务端）
  /tokens          显示当前会话估计 token 数
  /help            帮助

选项：
  --url           serve.py 的 OpenAI 端点（默认 http://127.0.0.1:8000/v1）
  --max-steps     最大工具调用轮数（默认 10）
  --budget        对话 token 预算（默认 6000；超限自动把最老的工具输出替换为占位符）
  --out-chars     单次工具输出截断长度（默认 1000 字符）
  --thinking on/off  思维链开关（默认 off，省 token）
  --yes           执行 shell 命令前不询问（默认逐条询问）
"""
import argparse
import json
import os
import subprocess
import sys
import urllib.request

SYSTEM = "你是命令行助手。通过调用工具完成任务。工具结果给你后，继续调用工具或给出简短最终答复。"

TOOLS = [
    {"type": "function", "function": {
        "name": "run_shell",
        "description": "执行 shell 命令并返回输出",
        "parameters": {"type": "object",
                       "properties": {"command": {"type": "string", "description": "shell 命令"}},
                       "required": ["command"]}}},
    {"type": "function", "function": {
        "name": "read_file",
        "description": "读取文本文件",
        "parameters": {"type": "object",
                       "properties": {"path": {"type": "string", "description": "文件路径"},
                                      "offset": {"type": "integer", "description": "起始行号(从1起)"},
                                      "limit": {"type": "integer", "description": "最多读取行数"}},
                       "required": ["path"]}}},
    {"type": "function", "function": {
        "name": "write_file",
        "description": "写入文本文件（覆盖）",
        "parameters": {"type": "object",
                       "properties": {"path": {"type": "string", "description": "文件路径"},
                                      "content": {"type": "string", "description": "文件内容"}},
                       "required": ["path", "content"]}}},
]


# ---------- 工具执行 ----------
def run_shell(command, assume_yes):
    if not assume_yes:
        ans = input(f"\033[33m执行命令?\033[0m {command}\n[y/N] ").strip().lower()
        if ans != "y":
            return "用户拒绝了该命令"
    try:
        r = subprocess.run(command, shell=True, capture_output=True, text=True, timeout=60)
        out = (r.stdout + r.stderr).strip()
        return out or f"(退出码 {r.returncode}，无输出)"
    except subprocess.TimeoutExpired:
        return "(命令超时 60s)"


def read_file(path, offset=None, limit=None):
    try:
        with open(path, errors="replace") as f:
            lines = f.readlines()
        start = max(0, (offset or 1) - 1)
        sel = lines[start: start + (limit or 200)]
        return "".join(sel) or "(空文件)"
    except Exception as e:
        return f"(读取失败: {e})"


def write_file(path, content):
    try:
        os.makedirs(os.path.dirname(os.path.abspath(path)), exist_ok=True)
        with open(path, "w") as f:
            f.write(content)
        return f"(已写入 {len(content)} 字符)"
    except Exception as e:
        return f"(写入失败: {e})"


def execute(call, assume_yes):
    fn = call["function"]
    try:
        args = json.loads(fn["arguments"] or "{}")
    except json.JSONDecodeError:
        return f"(参数 JSON 解析失败: {fn['arguments'][:100]!r})"
    if fn["name"] == "run_shell":
        return run_shell(args.get("command", ""), assume_yes)
    if fn["name"] == "read_file":
        return read_file(args.get("path", ""), args.get("offset"), args.get("limit"))
    if fn["name"] == "write_file":
        return write_file(args.get("path", ""), args.get("content", ""))
    return f"(未知工具: {fn['name']})"


# ---------- 客户端 ----------
def chat(url, messages, max_tokens, thinking, ablate=None, ablate_k=None):
    body = {"messages": messages, "tools": TOOLS, "max_tokens": max_tokens,
            "enable_thinking": thinking}
    if ablate is not None:
        body["ablate_refusal"] = ablate
    if ablate_k is not None:
        body["ablate_k"] = ablate_k
    req = urllib.request.Request(f"{url}/chat/completions", data=json.dumps(body).encode(),
                                 headers={"Content-Type": "application/json"})
    with urllib.request.urlopen(req, timeout=600) as r:
        resp = json.load(r)
    return resp["choices"][0]["message"], resp["choices"][0]["finish_reason"]


def estimate_tokens(messages):
    """粗略估计：中英文混合按 2 字符/token 偏保守"""
    return sum(len(json.dumps(m, ensure_ascii=False)) for m in messages) // 2


def shrink(messages, budget):
    """超预算时把最老的 tool 输出替换为占位符（保留系统提示与最近上下文）"""
    for m in messages:
        if estimate_tokens(messages) <= budget:
            break
        if m["role"] == "tool" and m["content"] != "[历史输出已省略]":
            m["content"] = "[历史输出已省略]"


def run_task(messages, task, args, ablate=None, ablate_k=None, ui=None):
    """执行一个任务的多轮工具循环。ui 非 None 时用 rich 渲染，否则纯文本。
    返回 True=完成，False=达到轮数上限/出错。"""
    messages.append({"role": "user", "content": task})
    for step in range(1, args.max_steps + 1):
        shrink(messages, args.budget)
        try:
            if ui is not None:
                with ui.status("[dim]思考中…[/]", spinner="dots"):
                    msg, finish = chat(args.url, messages, args.max_tokens,
                                       args.thinking == "on", ablate, ablate_k)
            else:
                msg, finish = chat(args.url, messages, args.max_tokens,
                                   args.thinking == "on", ablate, ablate_k)
        except urllib.error.HTTPError as e:
            print(f"[HTTP {e.code}] {e.read().decode()[:200]}")
            return False

        tool_calls = msg.get("tool_calls") or []
        if finish != "tool_calls" or not tool_calls:
            content = msg.get("content") or "(空)"
            if ui is not None:
                from rich.markdown import Markdown
                from rich.panel import Panel
                ui.print(Panel(Markdown(content), title=f"[green]助手[/]（第 {step} 轮）",
                               border_style="green"))
            else:
                print(f"\n=== 最终答复（第 {step} 轮）===\n{content}")
            return True

        messages.append({"role": "assistant", "content": msg.get("content") or "",
                         "tool_calls": tool_calls})
        for call in tool_calls:
            fn = call["function"]
            if ui is not None:
                ui.print(f"[cyan]🔧 step {step}[/] [bold]{fn['name']}[/]"
                         f"[dim]({fn['arguments'][:120]})[/]")
            else:
                print(f"[step {step}] {fn['name']}({fn['arguments'][:120]})")
            out = execute(call, args.yes)
            if len(out) > args.out_chars:
                out = out[:args.out_chars] + f"... [截断，共 {len(out)} 字符]"
            if ui is not None:
                ui.print(f"   [dim]→ {out[:150]!r}[/]")
            else:
                print(f"          → {out[:150]!r}")
            messages.append({"role": "tool", "content": out})

    print(f"\n达到最大轮数 {args.max_steps}，任务未完成。")
    return False


HELP_TEXT = """\
[bold]命令[/]：
  /quit, /exit      退出
  /reset            清空会话历史（保留系统提示）
  /yes              切换 shell 命令逐条确认开关
  /ablate off       本会话关闭消融
  /ablate on [k]    本会话开启消融，可选子空间维度 k（1–32）
  /ablate           跟随服务端默认
  /tokens           显示当前会话估计 token 数
  /help             本帮助
直接输入任务文本即可开始多轮工具调用。"""


def interactive(args):
    from rich.console import Console
    from rich.panel import Panel
    con = Console()

    health_txt = ""
    try:
        hurl = args.url.rstrip("/")
        hurl = hurl[:-3] + "/health" if hurl.endswith("/v1") else hurl + "/health"
        with urllib.request.urlopen(hurl, timeout=5) as r:
            h = json.load(r)
        health_txt = (f"模型 [bold]{h.get('model')}[/]（{h.get('device')}）"
                      f"｜服务端消融默认: {'开' if h.get('ablate_default') else '关'}")
    except Exception as e:
        con.print(f"[red]无法连接 {args.url}: {e}[/]")
        sys.exit(1)

    con.print(Panel(f"[bold]MiniAgent[/] — 极简小模型工具调用测试台\n{health_txt}\n"
                    f"token 预算 {args.budget}｜思维链 {args.thinking}｜输入 /help 查看命令",
                    border_style="cyan"))

    messages = [{"role": "system", "content": SYSTEM}]
    ablate, ablate_k = None, None   # None = 跟随服务端默认
    assume_yes = args.yes

    while True:
        try:
            line = con.input("[bold magenta]任务 ›[/] ").strip()
        except (EOFError, KeyboardInterrupt):
            con.print("\n再见。")
            return
        if not line:
            continue
        if line.startswith("/"):
            parts = line.split()
            cmd = parts[0].lower()
            if cmd in ("/quit", "/exit"):
                con.print("再见。")
                return
            elif cmd == "/reset":
                messages[:] = messages[:1]
                con.print("[dim]会话已清空。[/]")
            elif cmd == "/yes":
                assume_yes = not assume_yes
                args.yes = assume_yes
                con.print(f"[dim]shell 逐条确认: {'关（自动执行）' if assume_yes else '开'}[/]")
            elif cmd == "/ablate":
                if len(parts) == 1 or parts[1] == "auto":
                    ablate, ablate_k = None, None
                    con.print("[dim]消融: 跟随服务端默认[/]")
                elif parts[1] == "off":
                    ablate, ablate_k = False, None
                    con.print("[dim]消融: 本会话关闭[/]")
                elif parts[1] == "on":
                    ablate = True
                    if len(parts) > 2 and parts[2].isdigit():
                        ablate_k = max(1, min(32, int(parts[2])))
                    con.print(f"[dim]消融: 本会话开启，k={ablate_k or '服务端默认'}[/]")
                else:
                    con.print("[red]用法: /ablate [off|on [k]|auto][/]")
            elif cmd == "/tokens":
                con.print(f"[dim]会话估计 {estimate_tokens(messages)} token（预算 {args.budget}）[/]")
            elif cmd == "/help":
                con.print(HELP_TEXT)
            else:
                con.print(f"[red]未知命令 {cmd}，输入 /help[/]")
            continue
        run_task(messages, line, args, ablate=ablate, ablate_k=ablate_k, ui=con)


def main():
    p = argparse.ArgumentParser()
    p.add_argument("task", nargs="?", help="任务（省略则进入交互式终端界面）")
    p.add_argument("--url", default="http://127.0.0.1:8000/v1")
    p.add_argument("--max-steps", type=int, default=10)
    p.add_argument("--budget", type=int, default=6000)
    p.add_argument("--out-chars", type=int, default=1000)
    p.add_argument("--max-tokens", type=int, default=512)
    p.add_argument("--thinking", choices=["on", "off"], default="off")
    p.add_argument("--yes", action="store_true", help="shell 命令不再逐条确认")
    args = p.parse_args()

    if args.task is None:
        interactive(args)
        return

    messages = [{"role": "system", "content": SYSTEM}]
    ok = run_task(messages, args.task, args)
    sys.exit(0 if ok else 2)


if __name__ == "__main__":
    main()