信用证LC条款核对引擎·专业版

能力

确定性核对器：输入最迟装运日、有效期、交单期天数、证内条款全文、信用证类型、LC金额、合同金额与容差，自动输出总体风险等级（高/中/低）、四类核对明细、软条款命中清单与改证建议。

引擎源码（可直接运行）

# -*- coding: utf-8 -*-
"""信用证(LC)条款核对引擎 lc_checker.py

确定性核对规则：
1. 时间链：有效期 vs 最迟装运日（UCP600 交单默认 21 天）
   gap < 0 倒挂 / 0-7 天 / 8-14 天 / 15-20 天 / >=21 天
2. 软条款：关键词命中（客检/船样/申请人指示/进口许可证/指定船只/会签）
3. 信用证类型：可撤销 revocable 高风险
4. 金额：LC 金额 vs 合同金额，超出容差高风险
任何一项高风险 => 总体高风险。
"""
from datetime import date, datetime

# (风险名, 关键词列表，中英文)
SOFT_CLAUSE_KEYWORDS = [
    ("检验证书由申请人/买方授权代表签发",
     ["申请人授权", "申请人指派的检验", "申请人签署的检验", "买方授权代表",
      "authorized representative of the applicant", "applicant's authorized",
      "inspection certificate signed by the applicant", "inspection issued by applicant"]),
    ("装运/船样须经申请人确认",
     ["船样经买方确认", "船样经申请人确认", "样品须经申请人确认", "样品须经买方确认",
      "subject to applicant's confirmation", "subject to buyer's confirmation",
      "shipping sample subject to"]),
    ("以申请人指示/通知为付款前提",
     ["凭申请人指示付款", "收到申请人通知后付款", "upon applicant's instruction",
      "subject to applicant's instruction", "against applicant's instruction"]),
    ("以取得进口许可证为生效/付款前提",
     ["进口许可证签发后生效", "以取得进口许可证", "取得进口许可证为",
      "upon receipt of import license",
      "effective upon issuance of import license", "subject to import license"]),
    ("船只/船公司由申请人指定",
     ["由申请人指定船只", "船公司须经申请人同意", "指定船只由买方",
      "vessel to be nominated by applicant", "vessel nominated by the applicant",
      "shipping company subject to applicant"]),
    ("单据须申请人会签/回签",
     ["单据须经申请人会签", "申请人回签", "countersigned by the applicant",
      "countersignature of the applicant"]),
]


def _to_date(v):
    if isinstance(v, date):
        return v
    if isinstance(v, datetime):
        return v.date()
    if isinstance(v, str):
        for fmt in ("%Y-%m-%d", "%Y/%m/%d", "%Y.%m.%d"):
            try:
                return datetime.strptime(v.strip(), fmt).date()
            except ValueError:
                continue
    raise ValueError(f"日期格式无法解析: {v!r}（支持 YYYY-MM-DD / YYYY/MM/DD / YYYY.MM.DD）")


def detect_soft_clauses(clause_text):
    """返回命中软条款列表，每项 {risk, matched}。"""
    if not isinstance(clause_text, str) or not clause_text.strip():
        return []
    hits = []
    low = clause_text.lower()
    for name, kws in SOFT_CLAUSE_KEYWORDS:
        for kw in kws:
            if kw.lower() in low:
                hits.append({"risk": name, "matched": kw})
                break
    return hits


def check_time_chain(latest_shipment, expiry, presentation_days=21):
    """交单时间链核对。gap=有效期-最迟装运日（天）。"""
    s = _to_date(latest_shipment)
    e = _to_date(expiry)
    if not isinstance(presentation_days, int) or presentation_days <= 0:
        raise ValueError("交单期天数必须为正整数")
    gap = (e - s).days
    if gap < 0:
        level, msg = "高", f"有效期早于最迟装运日{abs(gap)}天，时间链倒挂，无法按期交单"
    elif gap <= 7:
        level, msg = "高", f"有效期距最迟装运日仅{gap}天（≤7天），交单窗口过短，极易逾期"
    elif gap < 15:
        level, msg = "中", f"有效期距最迟装运日{gap}天（8-14天），交单时间紧张，需加急制单"
    elif gap < presentation_days:
        level, msg = "中", f"交单窗口{gap}天，短于惯例默认{presentation_days}天（UCP600）"
    else:
        level, msg = "低", f"有效期距最迟装运日{gap}天（≥{presentation_days}天），交单时间充裕"
    return {"gap_days": gap, "level": level, "message": msg}


def check_lc_type(lc_type, clause_text=""):
    """信用证类型核对。UCP600 下不可撤销为默认；可撤销高风险。"""
    t = (lc_type or "").strip().lower()
    text = (clause_text or "").lower()
    if t in ("revocable", "可撤销") or ("revocable" in t and "irrevocable" not in t):
        return {"level": "高", "message": "信用证为可撤销(revocable)，开证行可单方面改/撤，受益人无保障"}
    if "this credit is revocable" in text and "irrevocable" not in text:
        return {"level": "高", "message": "条款文本含 revocable 且未见 irrevocable，可撤销风险"}
    if t in ("irrevocable", "不可撤销", ""):
        return {"level": "低", "message": "未发现可撤销条款（UCP600 项下默认不可撤销）"}
    return {"level": "中", "message": f"信用证类型未能明确判定（{lc_type}），请核实是否标注 irrevocable"}


def check_amount(lc_amount, contract_amount=None, tolerance=0.0):
    """金额核对。无合同金额时仅校验 LC 金额为正数。"""
    if lc_amount is None:
        raise ValueError("LC 金额不能为空")
    lc_amount = float(lc_amount)
    if lc_amount <= 0:
        raise ValueError("LC 金额必须为正数")
    if contract_amount is None:
        return {"level": "低", "message": "未提供合同金额，仅校验 LC 金额格式通过", "deviation_pct": None}
    contract_amount = float(contract_amount)
    if contract_amount <= 0:
        raise ValueError("合同金额必须为正数")
    if tolerance < 0 or tolerance > 1:
        raise ValueError("容差必须在 0~1 之间（如 0.05 表示 5%）")
    if contract_amount == 0:
        raise ValueError("合同金额不能为 0")
    dev = abs(lc_amount - contract_amount) / contract_amount
    if dev <= tolerance:
        return {"level": "低", "message": f"LC 金额与合同金额偏差 {dev*100:.2f}%，在容差 {tolerance*100:.0f}% 内", "deviation_pct": round(dev * 100, 2)}
    return {"level": "高", "message": f"LC 金额与合同金额偏差 {dev*100:.2f}%，超出容差 {tolerance*100:.0f}%，存在不符点风险", "deviation_pct": round(dev * 100, 2)}


def check_lc(latest_shipment, expiry, clause_text="", presentation_days=21,
             lc_type="", lc_amount=None, contract_amount=None, tolerance=0.0):
    """完整核对，返回结构化结论。"""
    if not isinstance(clause_text, str):
        raise ValueError("clause_text 必须为字符串")
    soft = detect_soft_clauses(clause_text)
    time_chain = check_time_chain(latest_shipment, expiry, presentation_days)
    type_ck = check_lc_type(lc_type, clause_text)
    amount_ck = check_amount(lc_amount, contract_amount, tolerance) if lc_amount is not None else {"level": "中", "message": "未提供 LC 金额，无法核对", "deviation_pct": None}

    items = [time_chain, type_ck, amount_ck]
    soft_level = "高" if soft else "低"
    levels = [it["level"] for it in items] + [soft_level]
    overall = "高" if "高" in levels else ("中" if "中" in levels else "低")

    suggestions = []
    if soft:
        suggestions.append(f"发现 {len(soft)} 条软条款，要求改证删除或改为由第三方中立机构（如SGS）出具单据")
    if time_chain["level"] != "低":
        suggestions.append("要求延展信用证有效期/最迟装运日，保证交单期≥21天")
    if type_ck["level"] == "高":
        suggestions.append("拒绝可撤销信用证，要求改开不可撤销跟单信用证")
    if amount_ck["level"] == "高":
        suggestions.append("核对合同与信用证金额、币种与溢短装条款，必要时改证")
    if not suggestions:
        suggestions.append("未发现高风险条款，按证制单并保留全套交单凭证")

    return {
        "overall_risk": overall,
        "soft_clauses": soft,
        "soft_clause_count": len(soft),
        "time_chain": time_chain,
        "lc_type_check": type_ck,
        "amount_check": amount_ck,
        "suggestions": suggestions,
    }

调用示例

from lc_checker import check_lc
from datetime import date

r = check_lc(
    latest_shipment=date(2026, 11, 10),
    expiry=date(2026, 11, 20),
    clause_text="Inspection certificate signed by the applicant must be presented.",
    lc_type="irrevocable",
    lc_amount=50000, contract_amount=50000,
)
print(r["overall_risk"])      # 高
print(r["soft_clauses"][0])   # 客检软条款命中
print(r["suggestions"])       # 改证建议

判定规则

• 时间链：gap<0 倒挂或≤7天为高，8-14天为中，15-20天短于交单期为中，≥交单期（默认21天）为低；
• 软条款：六类关键词（中英文）命中即高风险，返回风险名与命中词；
• 类型：revocable/文本含 revocable 且无 irrevocable 为高风险；
• 金额：偏差>容差（如5%）为高风险；
• 总体：任一高风险项即为高风险，无高风险但有中风险为中，否则为低。

边界处理（已覆盖）

• 日期支持 YYYY-MM-DD / YYYY/MM/DD / YYYY.MM.DD；
• 金额容差临界 5.00% 放行、5.01% 拦截；
• 非法日期、交单期非正整数、金额≤0、容差超出0-1、条款文本非字符串：抛 ValueError 拦截。

断言测试结果（31 项全过）

• 4 个完整正例（低风险全绿、客检+时间紧张、可撤销+倒挂+金额超差、中文双软条款）；
• 时间链 21/15/14/7/0/-1 临界逐档；
• 金额容差 5% 临界两组；
• 6 类非法入参全部拦截。

批量接入建议

• 到证后用 OCR/文本提取证内条款，循环调用本引擎逐条预审；
• 高风险证自动生成改证邮件草稿，交单证主管复核后发出；
• 核对结果与改证记录归档，形成单证风控台账。