#!/usr/bin/env node
/**
 * agent-claim-observer.js — P0 被动审计观察者 (v6.6-rc2)
 * AGENT_CLAIM_OBSERVER_P0
 *
 * SubagentStop 钩子 · 纯观察 · 不阻断 · fail-open
 * 记录 Agent 返回元数据到 debug/agent-returns.jsonl
 * 字段: {ts, traceId, session_id, agent_type, agent_id, text_length, pid}
 *
 * P0 观察期目标: 累积真实 Agent 返回数据, 为 P1 verifier 决策提供基线.
 */
'use strict';

const fs = require('fs');
const path = require('path');

let CLAUDE_ROOT;
try {
  CLAUDE_ROOT = require('./lib/root.js');
} catch {
  CLAUDE_ROOT = path.dirname(__dirname);
}
const LOG_FILE = path.join(CLAUDE_ROOT, 'debug', 'agent-returns.jsonl');
const WATCHDOG_MS = 3000;

function readStdinSync() {
  try {
    return JSON.parse(fs.readFileSync(0, 'utf8'));
  } catch {
    return null;
  }
}

function extractText(tr) {
  if (!tr) return '';
  if (typeof tr === 'string') return tr;
  if (typeof tr.content === 'string') return tr.content;
  if (Array.isArray(tr.content)) {
    return tr.content
      .filter(b => b && b.type === 'text' && typeof b.text === 'string')
      .map(b => b.text)
      .join('\n');
  }
  return '';
}

function extractTraceId(input, text) {
  // 正则有界 (8-64 hex-like), 防 ReDoS
  const re = /<trace>(bwr-[A-Za-z0-9-]{8,64})<\/trace>/;
  const prompt = (input && input.tool_input && input.tool_input.prompt) || '';
  const m1 = re.exec(prompt);
  if (m1) return m1[1];
  const m2 = re.exec(text);
  if (m2) return m2[1];
  return '';
}

function main() {
  const wdt = setTimeout(() => process.exit(0), WATCHDOG_MS);
  wdt.unref();
  try {
    const input = readStdinSync();
    if (input) {
      const text = extractText(input.tool_response);
      const traceId = extractTraceId(input, text);
      const record = {
        ts: new Date().toISOString(),
        traceId: traceId,
        session_id: input.session_id || '',
        agent_type: (input.tool_input && input.tool_input.subagent_type) || '',
        agent_id: input.agent_id || input.tool_use_id || '',
        text_length: text.length,
        pid: process.pid,
      };
      try { fs.mkdirSync(path.dirname(LOG_FILE), { recursive: true }); } catch {}
      fs.appendFileSync(LOG_FILE, JSON.stringify(record) + '\n');
    }
  } catch {
    // fail-open: 观察者异常不阻断主流程
  }
  clearTimeout(wdt);
  process.exit(0);
}

if (require.main === module) main();

module.exports = { extractText, extractTraceId };